Diagnostic capabilities bronchoalveolar lavage
M.V. Samsonova
Implementation in clinical practice fiberoptic bronchoscopy and bronchoalveolar lavage (BAL) techniques, which allow obtaining bronchial washes (BS) and bronchoalveolar washes (BAS), have significantly expanded the diagnostic capabilities in pulmonology. Thanks to the BAL technique it became possible use a whole range of cytological, bacteriological, immunological, biochemical and biophysical methods. These studies contribute to correct diagnosis oncological diseases and disseminated processes in the lungs, and also allow you to assess the activity inflammatory process in the bronchoalveolar space.
BAL technique
BAL is performed using fibrobronchoscopy under local or general anesthesia. The bronchoscope is inserted into the lobar bronchus (usually the middle lobe right lung), bronchial tree washed with a large amount of physiological solution heated to 37°C. After washing, the solution is completely aspirated from the bronchial tree.
The bronchoscope is inserted into the mouth of the segmental bronchus, occluding it. A polyethylene catheter is passed through the biopsy channel of the bronchoscope and 50 ml of saline is injected into the lumen of the segmental bronchus, which is then completely aspirated. The resulting portion of liquid is a bronchial wash. Then the catheter is advanced 6-7 cm deep into the segment.
Maria Viktorovna Samsonova -
doc. honey. sciences, head lab. pathological anatomy Research Institute of Pulmonology of Roszdrav.
bronchus and 4 portions of 50 ml of physiological solution are injected in fractions, which are completely aspirated each time. These mixed portions constitute the bronchoalveolar lavage.
Methods for studying BS and ALS
The main methods for studying BS and ALS include biochemical and immunological studies of the supernatant, as well as the study of cell sediment. At the same time, the viability of BS and ALS cells, a cytogram are calculated, cytochemical studies of the cells are carried out, as well as a cytobacterioscopic assessment. IN Lately a method has been developed for calculating the macrophage formula of ALS in various diseases bronchopulmonary system. The BAL study also allows you to assess the state of the surfactant system of the lungs by measuring surface tension and studying the phospholipid composition of the surfactant.
The bronchial portion of BAL is used to carry out qualitative and quantitative microbiological research. In addition, changes in the cellular composition of BS can determine the severity inflammatory reaction in the bronchial tree.
bronchial epithelium 5-20%
including
columnar epithelium 4-15% squamous epithelium 1-5%
alveolar macrophages 64-88% neutrophils 5-11%
lymphocytes 2-4%
mast cells 0-0.5%
eosinophils 0-0.5%
A normal cytogram of the alveolar portion of BAL (Fig. 1) is shown in Table. 1.
Diagnostic value of studying BS and ALS
Greatest diagnostic value the study of BS and BAS is intended to assess the degree of inflammation in the tracheobronchial tree, with lung tumors and alveolar proteinosis.
Cytological examination ALS has a high diagnostic value only for certain lung diseases. Such nosologies include histiocytosis X, in which Langer-Hans cells appear (in their cytoplasm when electron microscopy characteristic X-bodies are determined, according to the immunophenotype - these are CD1+ cells). With the help of BAS it is possible to confirm the presence of pulmonary hemorrhage. The study of ALS is also indicated in the verification of alveolar proteinosis, which is characterized by the presence of extracellular substance (Fig. 2), well determined using light (PIR reaction) and electron microscopy. In this disease, BAL serves not only as a diagnostic, but also as a therapeutic procedure.
Rice. 1. Normal cellular composition of ALS. Staining according to Romanovsky. x400.
In case of pneumoconiosis, using a BAS study it is only possible to confirm exposure to the dust agent. Specific diagnostics beryllium infection can be carried out by studying the functional proliferative activity of ALS cells in response to the action of beryllium salts. With asbestosis in the BAS, asbestos bodies can be detected (Fig. 3) in the form of characteristic fibers - both extracellularly and intracellularly. These bodies are asbestos fibers with hemosiderin, ferritin, and glycoprotein aggregated on them, so they stain well when performing the PAS reaction and Perls staining. It is extremely rare that asbestos bodies are found in persons who have had non-occupational contact with asbestos, and the concentration of such particles in BAS does not exceed 0.5 in 1 ml. Pseudoasbestos bodies can also be found in ALS - in pneumoconiosis associated with exposure to dust from coal, aluminum, glass fibers, etc.
In patients with immunodeficiency conditions (in particular, HIV infection), BAL is the method of choice for detecting pathogens of infectious lung lesions. The sensitivity of BAL fluid in diagnosing Pneumocystis infection (Fig. 4), according to some data, exceeds 95%.
For other diseases, BAL testing is not highly specific, but can provide Additional information, which is assessed in conjunction with clinical, radiological, functional and laboratory data.
With diffuse alveolar hemorrhage (DAH), which occurs in various diseases, free and phagocytosed erythrocytes and siderophages can be found in the ALS (Fig. 5). BAS serves effective method detecting BAV even in the absence of hemoptysis, when the diagnosis of this condition is extremely difficult. BAV should be differentiated from acute respiratory distress syndrome (ARDS),
in which siderophages also appear in the BAS.
Within differential diagnosis idiopathic fibrosing alveolitis (IFA), cytological examination of ALS allows one to exclude other interstitial lung diseases. Thus, a moderate increase in the proportion of neutrophils and eosinophils in ALS does not contradict the diagnosis of ELISA. A significant increase in the percentage of lymphocytes and eosinophils is not typical for ELISA, and in these cases one should think about other alveolitis (exogenous allergic, medicinal or occupational).
Cytological examination of ALS serves as a sensitive method in the diagnosis of exogenous allergic alveolitis (EAA). A high percentage of lymphocytes, the presence of plasma cells and mast cells, as well as “dust” macrophages in combination with anamnestic and laboratory data allows diagnosing EAA. Possible appearance of eosi-
Table 1. Normal ALS cytogram
Cellular composition of ALS Non-smokers Smokers
Cytosis, number of cells x106/ml 0.1-0.3 >0.3
Alveolar macrophages, % 82-98 94
Lymphocytes, % 7-12 5
Neutrophils,% 1-2 0.8
Eosinophils, %<1 0,6
Mast cells, %<1 <1
Rice. 2. Extracellular substance in ALS with alveolar proteinosis. Staining according to Romanovsky. x400.
nofils or giant multinucleated cells (Fig. 6). Among lymphocytes, cells with the immunophenotype C03+/C08+/C057+/C016- predominate. It should be remembered that several months after the onset of the disease, along with T-suppressors, the number of T-helpers begins to increase. Additional research methods make it possible to exclude other diseases in which there is an increase in the proportion of lymphocytes in the ALS - diffuse connective tissue diseases, drug-induced alveolitis (LA), obliterating bronchiolitis with organizing pneumonia (OBOP), silicosis.
In sarcoidosis, there is also an increase in the proportion of lymphocytes in the BAS, and sarcoidosis is characterized by co-
Rice. 4. Pneumocystis jiroveci in ALS. Staining according to Romanovsky. x400.
Rice. 5. Siderophages in ALS. Perls staining. x100.
www.atmosphere-ph.ru
Rice. 6. EAA: increased proportion of eosinophils, neutrophils, lymphocytes in ALS, multinucleated giant cell. Staining according to Romanovsky. x200.
Rice. 7. “Amiodarone lung” (LA): macrophages with foamy cytoplasm in ALS. Staining according to Romanovsky. x1000, oil immersion.
Rice. 8. Lymphocytic type of ALS cytogram. Staining according to Romanovsky. x1000, oil immersion.
the ratio of T-helpers and T-suppressors (CO4+/CD8+) is above 3.5 (the sensitivity of this sign is 55-95%, specificity is up to 88%). Multinucleated giant cells (a type of foreign body cell) may also be found in the ALS of patients with sarcoidosis.
Rice. 9. Neutrophilic type of ALS cytogram. Staining according to Romanovsky. x1000, oil immersion.
With medicinal alveoli-
Thus, morphological changes in the lungs can be varied; alveolar hemorrhagic syndrome or ABOP is often observed. In the cytogram of ALS, an increase in the proportion of eosinophils and neutrophils may be noted, but most often with LA opi-
Table 2. Examples of the use of cytological analysis of ALS for differential diagnosis (according to OgeP M. et al., 2000)
Cytogram indicators
ALS and their assessment
Clinical examples of ALS cytogram
Cytosis, x104/ml 29 110 100 20 64
Macrophages, % 65.8 18.2 19.6 65.7 41.0
Lymphocytes, % 33.2 61.6 51.0 14.8 12.2
Neutrophils, % 0.6 12.8 22.2 12.4 4.2
Eosinophils, % 0.2 6.2 7.0 6.8 42.2
Mast cells, % 0.2 1.0 0.2 0.3 0.4
Plasmocytes, % 0 0.2 0 0 0
CO4+/CO8+ ratio 3.6 1.8 1.9 2.8 0.8
Bacterial culture - - - - -
The most likely diagnosis is Sarcoidosis EAA LA ELISA OEP
Probability of correct diagnosis*, % 99.9 99.6 98.1 94.3 Not calculated
*Calculated using a mathematical model. Designations: AEP - acute eosinophilic pneumonia.
indicate an increase in the percentage of lymphocytes, among which, as a rule, CD8+ cells predominate. A very high content of neutrophils in BAS occurs when taking the antidepressant nomifensine (the proportion of neutrophils can reach 80%, followed by a subsequent decrease and a simultaneous increase in the number of lymphocytes). With amiodarone LA (“amiodarone lung”), specific changes in BAS occur in the form of the appearance of a large number of “foamy” macrophages (Fig. 7). This is a very sensitive, but low-specific sign: the same macrophages can be found in other diseases (EAA, OBOP), as well as in patients taking amiodarone in the absence of alveolitis (amiodarone increases the content of phospholipids, especially in phagocytes).
In other cases, when BAL does not reveal highly specific signs of any disease, this method makes it possible to limit the differential diagnostic search (Tables 2 and 3) to a certain group of nosological units with one or another type of alveolitis:
Lymphocytic (increased proportion of lymphocytes, Fig. 8): sarcoidosis, hypersensitivity pneumonitis, post-radiation pneumonia, ELISA, chronic infectious process in the lungs, AIDS, silicosis, Sjogren's syndrome, Crohn's disease, carcinomatosis, drug-induced pneumopathy;
Neutrophilic (increased proportion of neutrophils, Fig. 9): scleroderma, dermatomyositis, acute infectious process in the lungs, sarcoidosis in a malignant course, asbestosis, drug-induced alveolitis;
Eosinophilic (increased proportion of eosinophils, Fig. 10): Cher-ja-Strauss angiitis, eosinophilic pneumonia, drug-induced alveolitis;
Mixed (Fig. 11): tuberculosis. histiocytosis.
When diagnosing lung cancer, the BAL method has an advantage
Table 3. Cytological indicators of ALS are normal and their changes in various pathologies (according to OgeP M. et al., 2000)
Alveolar macrophages Lymphocytes Neutrophils Eosinophils Plasmocytes Mast cells CD4+/CD8+ ratio
Normal values
Non-smokers 9.5-10.5* 0.7-1.5* 0.05-0.25* 0.02-0.08* 0* 0.01-0.02* 2.2-2.8
85-95% 7,5-12,5% 1,0-2,0% 0,2-0,5% 0% 0,02-0,09%
Smokers 25-42* 0.8-1.8* 0.25-0.95* 0.10-0.35* 0* 0.10-0.35* 0.7-1.8
90-95% 3,5-7,5% 1,0-2,5% 0,3-0,8% 0% 0,02-1,0%
Non-infectious diseases
Sarcoidosis T = =/T - =/T T/=/4
EAA “Foamy” MF TT T =/T +/- TT 4/=
Medicinal “Foamy” MF TT T T +/- TT 4/=
alveolitis
ELISA T T/TT T - T =
OBOP “Foamy” MF T T T -/+ =/T 4
Eosinophilic T = TT +/- =/T 4
pneumonia
Alveolar “Foamy” MF T = = - N.d. T/=
proteinosis
Diseases of the joint - T =/T =/T - =/T T/=/4
body fabric
Pneumoconiosis VKV (particles) T T =/T - =/T T/=/4
Diffuse alveo- Color =/T T =/T - N.d. =
lary bleeding on Fe: +++
ARDS Coloring for Fe: + T TT T - =/T 4/=
Malignant tumors
Adenocarcinoma = = = - = =
Cancerous lymphangitis T T/= T/= -/+ T/= 4/=
Hemoblastosis T T T -/+ T 4/=
And infections
Bacterial BCV (bacteria) = TT T - N.d. =
Viral VKV T T T - N.d. T/=
Tuberculosis BCV (mycobacteria) T = T - T =
HIV VKV T T T/= - N.d. 4
Designations: MF - macrophages, VKV - intracellular inclusions; indicator: T - increased; TT - significantly increased; 4 - reduced; =/T - not changed, less often increased; T/=/4 - can be increased, decreased or not changed; T/TT - increased, less often significantly increased; T/= - increased, less often unchanged; 4/= - decreased, less often not changed; = - not changed; - No; -/+ - rare; +/- occur; N.d. - no data.
* Data are presented in absolute numbers x104ml-1.
before examining sputum to detect tumor cells, since the material may be
obtained from the lobe or segment where the tumor is localized. BAL makes it more likely
diagnose peripheral tumors, including bronchioloalveolar cancer (Fig. 12).
Rice. 10. Eosinophilic type of ALS cytogram, Char-co-Leiden crystals. Staining according to Romanovsky. x200.
Rice. 11. Mixed type of ALS cytogram: increased proportion of lymphocytes, neutrophils, eosinophils. Staining according to Romanovsky. x1000, oil immersion.
Rice. 13. ALS in chronic bronchitis: the presence of cylindrical ciliated cells, neutrophils, accumulation of coccal flora. Staining according to Romanovsky. x1000, oil immersion.
Rice. 14. Mycobacterium tuberculosis in ALS. Ziehl-Neelsen staining. x1000, oil immersion.
Rice. 15. Pseudomycelium of the fungus Candida albicans in ALS. Staining according to Romanovsky. x200.
The cytobacterioscopic method makes it possible to identify and semi-quantitatively assess the content of bacteria (Fig. 13), mycobacteria (Fig. 14) and fungi (Fig. 15) in BAS. These results (bacteria can be differentiated by Gram) serve as the basis for prescribing appropriate antibacterial therapy until the results of bacteriological examination are obtained. In casuistic
Rice. 16. Significant increase in the number of neutrophils in ALS, numerous protozoa such as amoebas. Staining according to Romanovsky. x200.
The study of BAS allows one to assess the degree of activity of the inflammatory process in infectious diseases and the effectiveness of the therapy. A low degree of inflammatory activity is characterized by an increase in the proportion of neutrophils in BAS within 10%,
medium - up to 11-30%, high - more than 30%.
The use of histochemical methods for studying BAL cells is possible if their viability is high (more than 80%).
Conclusion
When assessing changes identified in BS and BAS, you should adhere to certain rules and remember the following:
The identified changes are characteristic only of the segment under study, so they should be treated with caution if the process is not diffuse in nature;
The identified changes are typical for a given point in time;
Since the lungs are simultaneously exposed to many factors (smoking, pollutants, etc.), it is always necessary to exclude the possibility of the influence of these factors on the development of pulmonary pathology.
Chernyaev A.L., Samsonova M.V. Pathological anatomy of the lungs: Atlas / Ed. Chuchalina A.G. M., 2004.
Shapiro N.A. Cytological diagnosis of lung diseases: Color atlas. T. 2. M., 2005.
Baughman R.P Bronchoalveolar Lavage. St. Louis, 1992.
Costabel U. Atlas of Bronchoalveolar Lavage. L., 1998.
Drent M. et al. //Eur. Resp. Monograph. V 5. Mon. 14. Huddersfield, 2000. P. 63.
Books from the Publishing House “ATMOSPHE”
Amelina E.L. etc. Mucoactive therapy /
Ed. A.G. Chuchalina, A.S. Belevsky
The monograph summarizes modern ideas about the structure and functioning of mucociliary clearance, its disorders in various respiratory diseases, research methods; The main medicinal and non-medicinal methods for correcting mucociliary clearance in bronchopulmonary pathology are considered. 128 p., ill.
For general practitioners, therapists, pulmonologists, medical students.
Today, fiberoptic bronchoscopy is a common standard diagnostic procedure that allows direct examination of the upper and lower airways. As the endoscope moves through the nasopharynx and trachea, large bronchi can easily determine the amount of mucus, as well as the degree of swelling of the mucous membrane and bronchospasm. In addition to examining the lumen of the airways, one of the great advantages of bronchoscopy is the ability to take samples from large and small airways and alveoli. The resulting samples are then analyzed for their cellular and non-cellular constituents.
In recent years, in cases of suspected diffuse inflammatory disease, bronchoalveolar lavage (BAL) using an endoscope or special tube has become somewhat more popular than more traditional methods of obtaining samples such as tracheal aspiration. For many years, it was believed that obtaining samples from the lower trachea provides representative information about the condition of the alveoli and small airways, since free airway cells from the peripheral lung are eventually flushed toward the trachea for removal.
However, a large case study of young performance horses with low performance associated with lower respiratory tract pathology found that cytologic and bacteriologic findings were poorly correlated between specimens obtained by tracheal aspiration and those obtained by BAL. Studies have shown that the numbers of different cells in cytological preparations from tracheal aspirates and BAL from the same horse varied significantly. This suggests that samples from tracheal fluid collections may not accurately reflect the population of cells and secretions present within the small airways and alveoli. This is important because exercise intolerance, inflammatory airway damage, and hyperresponsiveness are associated with small airway disease, and the best diagnostic method is BAL cytology. In addition, bacterial culture of tracheal aspirates yielded more positive results than culture of BAL performed on the same case. Thus, the lower part of the trachea apparently contains normal bacterial flora, which may be absent in the small airways and alveoli. For these reasons, BAL has become an increasingly popular tool for assessing inflammation of the distal (small) airways compared with obtaining samples by tracheal aspiration.
To substantiate the value of differential cell abundance in BAL fluid as an additional diagnostic tool for the evaluation of the respiratory system, other quantitative measurements are needed in addition to routine clinical examination. Emphysema syndrome has been studied in detail over the past two decades, and several research laboratories around the world have clearly demonstrated a high correlation between BAL cell differentiation and pulmonary function and histamine bronchochallenge testing in emphysema horses. In recent years, similarly characterized lung function in young performance horses with non-infectious inflammatory airway disease (IAD) has been consistent with these findings regarding the diagnostic utility of bronchoalveolar lavage.
The purpose of this chapter is to discuss the use of bronchoalveolar lavage technique as a tool to identify and characterize inflammation in the lungs of horses that suffer from diffuse pulmonary pathology, such as IAD in young performance horses and emphysema syndrome in adult animals. In addition, viral and bacterial lung diseases are briefly reviewed in terms of their diagnosis using bronchoalveolar lavage.
INDICATIONS FOR BRONCHOALVEOLAR LAVAGE
Inflammation of the lower respiratory tract in horses can develop for various reasons. Horses of any age can suffer from infectious (bacterial/viral) and non-infectious IAD and may exhibit a variety of clinical, physiological and pathological signs. In a large prospective study of 2- to 3-year-old Thoroughbred horses in training, cough and nasal discharge were second only to lameness as the most common reason for missed training days. Non-infectious IAD is the most common respiratory pathology occurring in both young and adult performance horses.
The dominant feature of IAD is airway obstruction resulting from accumulation of secretions, thickening of the airway walls, transformation of the airways and, ultimately, in advanced cases, loss of the ability to maintain the diameter of the lumen of the small airways. Airway hyperresponsiveness is a consequence of the inflammatory process and leads to further obstruction due to bronchospasm and other functional abnormalities. In healthy horses, bronchospasm occurs in response to inhalation of a histamine aerosol at a concentration of 16 mg/ml. In contrast, in older horses with emphysema, bronchoconstriction occurs from inhaled histamine concentrations of less than 8 mg/ml. In performance horses 2 to 5 years of age with IAD, bronchoconstriction occurs in response to inhaled histamine at concentrations as low as 2 to 3 mg/mL, indicating even greater airway hyperresponsiveness. This severe airway hyperresponsiveness correlates with increased levels of inflammatory cells in BAL samples, and BAL is therefore an extremely useful tool for investigating the nature and basis of inflammatory airway disease.
The prevalence of poor performance due to respiratory problems is significant, especially in racehorses. Common respiratory abnormalities in this animal population include IAD, exercise-induced pulmonary hemorrhage, and upper airway dysfunction. In this context, IAD makes a significant contribution to substandard athletic performance, interrupted racing or training, and ultimately the premature end of a sporting career. Histological examination of lung specimens from older horses (>10 years) revealed a significant prevalence of non-infectious IAD in this age group. Therefore, IAD plays a significant role in the health and performance of horses of all age groups and sporting disciplines. Bronchoscopy and bronchoalveolar lavage to determine the nature and extent of such inflammation are extremely important to determine appropriate treatment and prognosis in each case.
Less common pathologies, but also significant for performance horses of all ages, are septic lung diseases such as lung abscesses and parapneumonic effusions. Abscesses are usually localized in the cranial part of the right or left caudal lobe of the lung." These diseases can be easily recognized clinically due to the presence of increased body temperature, anorexia and pain on palpation of the chest. Suspicion of bronchopneumonia or lung abscess is confirmed by radiography. However, in such patients, -There is still value in bronchoscopy for both diagnostic and therapeutic purposes. During bronchoscopy, reddish-brown mucous secretions in the lower trachea are easily detected. Gently moving the endoscope deeper around this collection, being careful not to touch these secretions, is often possible follow the strip of discolored mucopurulent secretion and identify the specific segmental bronchial source.Then, using the biopsy channel of the bronchoscope, a polyethylene catheter can be inserted into the specific bronchus in order to obtain a sterile sample of secretions for bacterial culture and cytological analysis. Once this procedure is completed, a small volume of fluid (approximately 200-250 ml in 2 or 3 injections) can be infused into the affected bronchus and immediately aspirated to remove excess exudate. This process is called "toilet" of the airways, not bronchoalveolar lavage. This procedure provides therapeutic benefits by reducing bacterial attack and reducing exudative overload in the affected region of the lung. After the final suction of the fluid and before removing the endoscope, a dose of dissolved antibiotic can be locally injected into the affected area. This procedure may be repeated daily or every other day as a component of treatment for bacterial bronchopneumonia in combination with systemic therapy.
BRONCHOALVEOLAR LAVAGE PROCEDURE
BAL can be performed in most horses under mild sedation (xylazine 0.3-0.5 mg/kg IV or romifidine 0.03-0.05 mg/kg IV) and airway anesthesia with local anesthetic (0.4% lidocaine without epinephrine). This procedure can be performed using a 1.8-2 m bronchoscope or a special BAL tube (Bivona Medical Technologies, Gary, Ind.). When the bronchoscope or BAL tube is in contact with the trachea, reaching the tracheal bifurcation usually provokes coughing. Therefore, at this stage it is useful to infuse 60-100 ml of pre-warmed lidocaine solution (0.4% without epinephrine) to desensitize the cough receptors located in the bifurcation. After this infusion, the endoscope or BAL tube is carefully, without excessive force (this is determined by the degree of resistance to further advancement ) is introduced deeper. Pre-warmed saline (200-300 ml) is quickly infused into the lung and then aspirated.
The total volume of saline solution for infusion should be divided into two separate boluses, while trying to get as much fluid as possible between each bolus. In general, a return of 40-60% of the total infusate volume indicates a satisfactory BAL. In horses with advanced disease, small volumes are collected and there is a lesser tendency for less foam (surfactant) to be present. BAL fluid samples are then pooled and kept on ice if processing is not possible within 1 hour of receipt. The fluid should be assessed macroscopically to identify any flocculent debris or discoloration. One or two serum or EDTA tubes are filled with VAL fluid and centrifuged (1500 rpm for 10 minutes); After removing the supernatant, smears are prepared from a drop of sediment, which are then air-dried. When preparing smears, slides must be air dried quickly using a small tabletop fan to well preserve cell morphology. Smears prepared in this way can be stored at room temperature for up to 8-10 months with minor cellular changes. Air-dried smears can be stained with Diff-Qnik, Wright-Giemsa, May Grmnwald, Leishman, or Gram stains for interpretation of cellular and noncellular components. Cellular profile and morphology may provide clues to the nature of airway injury, inflammation, and the lung's immunological response to infection or foreign antigens.
DIFFERENTIAL COUNTING OF CELLS IN BAL AND THEIR INTERPRETATION
In the field, the volume of fluid administered often varies, ranging from 60 to 300 ml of sterile saline per VAL. Additionally, in horses with severe bronchospasm, the volume of fluid withdrawn may be significantly reduced. Due to these circumstances, the dilution effect makes it difficult to accurately count the total number of nucleated cells, and given the wide range of TaKoii values, the count is of little clinical value in the interpretation of inflammatory conditions of the lungs and is considered to have no diagnostic value.
On the other hand, differential abundance of cell types is largely unaffected by dilution and is valuable for characterizing pathological increases in specific cell populations. Thus, with the help of differential cell counting, it is possible to identify the characteristic features of septic, non-septic and viral inflammatory diseases of the respiratory tract, which helps in deciding on the therapeutic approach in each specific case. Ranges of values were established for differential BAL cell abundance in healthy horses, horses with emphysema, and performance horses with poor performance. In each of the corresponding groups, characteristic cytological features are present.
Differential cell counting in healthy horses
Ranges of differential BAL cell counts were established by obtaining BAL samples from horses not suffering from respiratory disease and were confirmed by various methods. including clinical examination, testing of pulmonary function and, in some cases, the absence of airway hyperresponsiveness in response to bronchoprovocation with histamine aerosol (Fig. 8.2-1). In young horses (6 years of age), the neutrophil population can average up to 15% of healthy animals (based on the diagnostic methods described above), with a corresponding decrease in the percentage of the macrophage and lymphocyte population.
Deviations in differential cell numbers
Emphysema syndrome is a commonly diagnosed respiratory disease in adult horses with a characteristic history, clinical signs, abnormal pulmonary function testing, and airway hyperresponsiveness. Horses with exacerbation of emphysema have at least 23% neutrophils in the BAL fluid (Figure 8.2-2). However, in such cases, neutrophils often account for more than a third of the differential abundance of all inflammatory cells and play a major role in the clinical syndrome and the aforementioned airway hyperresponsiveness. BAL cytology specimens from emphysema horses often have a rich mucus background with many nontoxic and apoptotic (senescent) neutrophils. trapped inside this slime. In the BAL fluid of horses suffering from emphysema, in addition to the increased number of neutrophils, there is also a significant increase in the total number of mast cells, eosinophils, lymphocytes, macrophages and epithelial cells. These cells must be recognized and assessed separately from neutrophils. The number of desquamated epithelial cells is usually increased as a result of damage to the lining of the mucosa due to severe inflammation. In horses suffering from emphysema, in addition to the glandular higher cellular components, non-cellular structures, such as Kurschmann coils, are often present in BAL preparations, which indicate chronic nonseptic inflammatory disease of the respiratory tract.
CONCLUSION
BAL is clearly emerging as a powerful adjuvant diagnostic tool to aid in the diagnosis of clinical and subclinical lower respiratory tract diseases, such as non-infectious inflammatory airway disease in young performance horses and recurrent airway obstruction, or emphysema, in older horses. The BAL cell differential for healthy horses has been well established using generally accepted standardized procedures, and any deviation of cytological profiles from normal values will help recognize a wide range of non-septic inflammatory processes. Although clinicians currently prescribe specific treatments based on BAL cell differential cytology, greater knowledge regarding various disorders may in the future allow equine clinicians to provide more accurate prognostic information regarding respiratory problems to trainers, athletes and owners. In addition, in most young and adult sport horses with copious amounts of white mucopurulent secretion in the respiratory tract and a markedly increased percentage of neutrophils in the cellular differential, a septic process cannot be detected. Rather, such cases demonstrate a nonseptic inflammatory disease of the airways.
Bronchoalveolar diagnostic lavage is a research method that provides the extraction of cellular elements, proteins and other substances from the surface of the smallest bronchi and alveoli by filling a subsegment of the lung with an isotonic solution followed by aspiration. Diagnostic subsegmental bronchoalveolar lavage is usually performed during bronchofibroscopy under local anesthesia after bringing the bronchofibroscope to the mouth of the subsegmental bronchus. Through the channel of the bronchofiberscope, 50-60 ml of an isotonic solution is instilled into the subsegmental bronchus. The liquid coming from the bronchial lumen, which is broncho-alveolar lavage, is aspirated through the bronchofiberscope channel into a plastic cup. Instillation and aspiration are repeated 2-3 times. In the aspirated liquid, cleared of mucus by filtering through gauze, the cellular and protein composition and functional activity of alveolar macrophages are studied. To study the cellular composition, the bronchoalveolar lavage is centrifuged. Smears are prepared from the sediment and stained with hematoxylin-eosin or Romanovsky. Diagnostic bronchoalveolar lavage is more often used to determine the activity of disseminated processes in the lung. A sign of high activity of idiopathic fibrosing alveolitis is a significant increase in the number of neutrophils in the bronchoalveolar lavage, and in sarcoidosis and exogenous allergic alveolitis - an increase in the number of lymphocytes.
BRONCHALVEOLAR MEDICAL LAVAGE
A method of treating lung diseases based on the endobronchial administration of a large amount of isotonic solution and washing out clots of mucus, protein and other contents of the small bronchi and alveoli. Therapeutic bronchoalveolar lavage can be performed through a bronchoscope or a double-lumen endotracheal tube. The procedure is usually performed under anesthesia. Artificial ventilation of the lungs is carried out using the injection method. An isotonic solution is sequentially instilled into each lobar or segmental bronchus through a controlled catheter and immediately aspirated along with the washed-out viscous secretion and mucus clots. The bronchoscopic technique is more often used in patients with bronchial asthma in status asthmaticus. To wash the bronchi, 500-1500 ml of isotonic solution is used. It is usually possible to aspirate about 1/3 - 1/2 of the injected volume of liquid. Indications for therapeutic bronchoalveolar lavage in patients with bronchial asthma rarely arise, since a complex of other therapeutic measures usually helps to relieve status asthmaticus.
Therapeutic bronchoalveolar lavage through a double-lumen endotracheal tube is performed with single-lung artificial ventilation. A catheter is inserted into the lumen of the endotracheal tube into the main bronchus, through which instillation and aspiration of an isotonic solution are carried out. 1000-1500 ml of solution is injected into the lung at once, and 90-95% of the volume of injected liquid is aspirated back. The procedure is repeated several times. The total volume of injected fluid varies from 3-5 to 40 liters. Total bronchoalveolar lavage through a double-lumen endotracheal tube is the most effective treatment for idiopathic alveolar proteinosis.
Directory in Pulmonology / Ed. N. V. Putova, G. B. Fedoseeva, A. G. Khomenko. - L.: Medicine
Lynelle R. Johnson DVM, PhD, Dip ACVIM (Internal Medicine)
University of California, USA
Basic provisions
Most often, tracheal collapse occurs in small breed, middle-aged dogs with excess body weight. Sometimes this pathology occurs in young large dogs.
Tracheal collapse most often occurs in the dorsoventral direction. It is preceded by weakening and thinning of the cartilaginous rings of the trachea, as a result of which prolapse of the posterior wall of the trachea into its lumen is observed.
Collapse of the cervical trachea most often occurs during inspiration, and collapse of the thoracic trachea most often occurs during expiration.
The best way to diagnose is a visual examination of the respiratory tract. Bronchoscopy can be used to obtain air samples from deep parts of the respiratory tract.
Tracheal collapse is a consequence of irreversible pathology of the cartilaginous rings of the trachea. Treatment involves maintaining good upper and lower respiratory tract health.
In dogs with dyspnea and severe cough associated with cervical tracheal collapse, surgical intervention and replacement of the tracheal section with damaged cartilage rings is indicated.
Introduction
Tracheal collapse is quite common in veterinary practice. It causes coughing and airway obstruction in small breed dogs. Sometimes this pathology occurs in young dogs of large breeds. Although the reasons for the development of tracheal collapse are not fully known, it is believed that this pathology is a consequence of congenital abnormalities, in particular, a genetic disorder of chondrogenesis. Often tracheal collapse develops due to chronic diseases of the respiratory tract, cartilage degeneration, trauma and insufficient innervation of the tracheal muscle (musculus trachealis dorsatis). Most often, tracheal collapse develops in the dorsoventral direction with prolapse of the weak dorsal tracheal membrane into the tracheal lumen.
Recognizing tracheal collapse in a clinical setting is quite simple. Identifying the degree of breathing difficulty in an animal, factors that contribute to increased coughing, and early intervention help select the appropriate treatment for the patient, which improves the outcome of the disease and reduces the likelihood of severe complications.
Physiology and pathophysiology
The walls of the trachea are reinforced with 30-45 rings of hyaline cartilage. The ends of the cartilaginous structures are fastened on the dorsal side of the trachea to form a complete ring (Figure 1). The tracheal rings are connected to each other by annular ligaments. The inside of the trachea is lined with pseudostratified, ciliated and columnar epithelium. In the upper respiratory tract, in the epithelial layer, Goblet cells are found, which produce mucus lining the epithelium. This mucus and the ciliated apparatus of the epithelial cells are part of the mechanism that protects the lungs from damage.
The trachea is a unique structure: in its cervical region the internal pressure is atmospheric, while in the thoracic region it is negative (corresponding to the pressure in the pleural cavity) (Figure 2a). As you inhale, the chest expands and the diaphragm moves toward the abdominal cavity. As a result, the volume of the pleural cavity increases and the pressure in it decreases (Figure 26). A wave of low pressure is transmitted through the respiratory tract, resulting in air entering the lungs. When you exhale, the pressure in the pleural cavity increases, and the pressure gradient forces air out of the airways. In healthy animals, tracheal cartilaginous rings completely prevent significant changes in tracheal diameter during phases of the respiratory cycle.
In dogs with tracheal collapse, the cartilage rings lose their elasticity and lose their ability to prevent changes in tracheal diameter during breathing due to pressure fluctuations. Some small breed dogs with tracheal collapse have an insufficient number of chondrocytes and a decrease in the content of chondroitin sulfate and calcium in the cartilage of the respiratory tract. It is believed that the lack of glycoproteins and glycosaminoglycans causes a significant decrease in the amount of bound water in cartilage tissue, drying out and thinning of the cartilage. Pathological changes detected in the cartilage of the respiratory tract in dogs with tracheal collapse may be associated with both impaired chondrogenesis and degeneration of hyaline cartilage. The cause of an insufficient number of chondrocytes can be both genetic factors and dietary deviations.
In sick dogs, tracheal collapse occurs in different parts of the trachea depending on the phase of the respiratory cycle (Figure 2, b and c). Weakened cartilaginous rings in the cervical trachea lose their ability to withstand negative pressure during inspiration, which is why the trachea collapses (collapses) in the dorsoventral direction. With repeated or permanent collapse, the cartilaginous rings become deformed, stretching the dorsal wall of the trachea. This wall bends into the lumen, irritating the opposite wall, causing damage and inflammation of the tracheal epithelium. Due to inflammation, mucus secretion increases and the number of cells producing mucoid mucus increases. The amount of mucopurulent secretion can be so great that a film is formed, similar to that formed during diphtheria. All this causes the patient to cough, disrupts the functioning of the ciliary apparatus of the respiratory tract and significantly increases the risk of infection.
Picture 1.
Endoscopic picture of a normal trachea. C-shaped cartilaginous rings are visible, the ends of which are connected by the dorsal tracheal membrane (in this photo- up). Blood vessels are visible through the respiratory epithelium.
In many sick dogs, collapses involve not only the cervical, but also the thoracic trachea, main bronchi and even small airways. With intense exhalation or coughing, positive pressure arises in the pleural cavity and is transmitted to the respiratory tract. Therefore, collapse of the thoracic airways usually occurs during exhalation (Figure 2c). It is unknown whether the number of chondrocytes in the cartilaginous rings of the thoracic trachea is reduced in dogs with tracheal collapse. Sometimes dogs also experience generalized collapse of the entire thoracic respiratory tract.
History and symptoms of the disease
Most often, tracheal collapse occurs in dogs of small and toy breeds: Chihuahuas. Pomeranians, toy poodles, Yorkshire terriers, Maltese dogs and pugs. The age of dogs that first show signs of the disease varies from 1 year to 15 years. However, the disease most often appears in adulthood. No gender predisposition to the disease has been identified. Tracheal collapse is also rare in young large breed dogs (such as golden retrievers or Labrador retrievers).
Most dogs with a collapsed trachea have bouts of severe coughing for a long time. In general, pet owners describe this cough as “dry,” “booming,” and gradually increasing in severity. Often, owners indicate that their dog's coughing attacks begin after eating or drinking. As a result, some dogs begin to feel sick, the animals may choke on food, or even vomit. In some cases, such coughing attacks develop so acutely that the owners feel that a foreign body has entered the dog’s trachea. The cough gradually becomes paroxysmal and is accompanied by secondary damage to the respiratory tract. Shortness of breath develops, breathing rate increases, and physical endurance decreases. When the load on the respiratory system increases (for example, due to physical activity, increased temperature or humidity), signs of respiratory failure are observed. Often after intratracheal intubation the severity of clinical symptoms increases. Exacerbation of symptoms can also be caused by physical activity or a sharp tug on the collar. Pet owners, fearing the deterioration of their pets’ condition, often limit their physical activity. As a result, many dogs become overweight and have significantly reduced exercise capacity. According to the author’s observations, it is in overweight dogs that the load on the respiratory system is especially high. In obese animals, the severity of the clinical symptoms of tracheal collapse (especially cough) can be very pronounced. However, in the literature, among dogs undergoing surgery for tracheal collapse, only 9% were severely obese (4).
In the presence of collapse of the cervical trachea, dogs experience shortness of breath on inspiration. The animal puffs heavily, drawing in air with difficulty. Auscultation reveals stridor and other coarse rales in the airways. Such auscultatory symptoms are characteristic of collapse of the cervical trachea and concomitant laryngeal paralysis. With the development of swelling of the laryngeal sacs, symptoms of upper respiratory tract obstruction may appear. It manifests itself in the form of a transient “wrenching” cough and high inspiratory pressure.
Figure 2a. Sections of the trachea and the pressure that acts on individual sections of the respiratory tract: the cervical section of the trachea is exposed to atmospheric pressure, and the thoracic- pleural.
Figure 26. As you inhale, the diaphragm expands and moves back. As a result, the pressure in the pleural cavity becomes negative. A wave of negative pressure is transmitted through the respiratory tract and forces atmospheric air into the lungs. In dogs with tracheal collapse, the trachea loses its elasticity and ability to withstand changes in pressure. As a result, during inhalation it falls in the dorsoventral direction.
Figure 2c. With forced exhalation or coughing, pleural pressure becomes positive. This ensures the opening of the airways in the chest. However, if the cartilage rings are not rigid enough, collapse occurs.
When a dog develops chronic bronchitis, aggravated by collapse of the cervical or thoracic trachea, the cough becomes harsh, becomes constant and is accompanied by sputum production. Rarely, dogs with cervical or thoracic tracheal collapse experience transient hypoxemia leading to syncope. Often such fainting occurs during coughing attacks. However, in some dogs, syncope is secondary to the development of pulmonary hypertension and hypoxia.
Clinical examination
Dogs with tracheal collapse appear healthy in appearance at rest. Even during coughing attacks, their condition does not cause alarm. Any dog with signs of systemic diseases should be examined for the presence of pathologies that cause coughing attacks (heart failure, pneumonia, neoplasms of the respiratory tract). A thorough general clinical examination will clarify the cause of the cough and identify concomitant diseases.
Figure 3.
Inspiratory radiograph of the respiratory tract of a 10-year-old Yorkshire Terrier. The dog had coughing attacks, shortness of breath, and cyanosis for 2 months. The radiograph obtained in the lateral projection shows collapse of the cervical trachea, extending up to the entrance of the trachea into the chest. The thoracic aorta is slightly dilated. X-ray courtesy of Dr. Anne Babr)
Examination of the respiratory system should begin with careful auscultation and gentle palpation of the trachea and larynx. The presence of palpable laryngeal sacs indicates a dysfunction of this organ. According to some researchers, such dysfunction develops in 20-30% of dogs with tracheal collapse (5, 6). Turbulization of air flow in a narrowed area of the trachea leads to the generation of characteristic sounds heard during auscultation of the trachea. In some dogs with tracheal collapse, the trachea is extremely sensitive, so extreme care should be taken during examination to prevent stimulation of an attack. When palpating the trachea, in some cases of collapse, it is possible to identify excessive compliance or softness of its cartilaginous rings.
In dogs with uncomplicated collapse of the large airways, respiratory sounds in the lungs are often normal. However, it can be difficult to conduct an auscultatory examination in such cases due to shortness of breath, rapid breathing and obesity (as a result of which respiratory sounds are muffled). In addition, strong sounds in the upper respiratory tract drown out weak bronchoalveolar sounds. Pathological noises in the lungs (wheezing and whistling) often make it possible to diagnose the nature of the pathology. Wheezing in the lungs usually indicates air passing through fluid-filled alveoli or mucus-blocked airways. Soft wheezing on inspiration may be a sign of pulmonary edema; harsher and louder wheezes are characteristic of dogs with pneumonia and pulmonary fibrosis. Whistles are longer sounds, usually heard while exhaling. They are typical for animals with chronic bronchitis. A characteristic sign of damage to the small respiratory tract is also abdominal tension during exhalation.
Small breed dogs often have heart valve insufficiency. As a result, heart murmurs can make it particularly difficult to diagnose the causes of cough by auscultation. Tachycardia is usually observed in congestive heart failure. In diseases of the respiratory tract, the heart rate is usually maintained, but severe sinus arrhythmia develops. When the respiratory system is stressed, tachycardia may appear in such animals, which significantly complicates diagnosis. It is especially difficult to diagnose the disease in small dogs suffering from congestive heart failure and pathologies of the trachea and bronchi. In such cases, X-ray examination is indicated.
Diagnostics
Although the diagnosis of tracheal collapse can be made based on history and clinical symptoms, a general clinical examination of the sick animal is necessary to determine concomitant diseases and prescribe individual treatment. To diagnose concomitant diseases, it is recommended to do a complete blood test, including determination of the number of cells and biochemical parameters of the serum, and a urine test.
Visualization methods
To clarify the diagnosis of tracheal collapse and identify concomitant diseases of the lungs and heart, the use of radiography is indicated. Usually, radiographs are obtained in standard projections, but it is better to obtain radiographs in the ventrodorsal projection during inhalation and exhalation. On radiographs obtained during full inspiration, collapse in the cervical trachea is clearly visible. The thoracic section of the trachea can be expanded (Figure 3, 4a). Collapse of the main bronchi, thoracic trachea, or a combination is usually visible on radiographs obtained during full expiration. The cervical part of the trachea is inflated (Figure 46).
The accuracy of diagnosis increases if a coughing attack is provoked during an X-ray examination. Unfortunately, it is difficult to correctly interpret airway dynamics from static radiographs. According to some studies, radiographs can detect tracheal collapse in only 60-84% of cases (4, 5). Radiographic visualization of the trachea is often difficult due to overlapping images of the esophagus or cervical muscles. In such cases, during radiographic examination, the use of a non-standard projection, from bottom to top, is effective. This projection allows the identification of collapsed areas in the cervical trachea, although it may be difficult to correctly direct the X-ray beam. During mass fluoroscopic examinations in dog kennels, it is possible to identify cases of transient collapse of the respiratory tract. The same method can identify the phase of the respiratory cycle during which collapse develops.
Pictures 4. Radiographs of the respiratory tract of a 13-year-old poodle suffering from coughing attacks for a long time.
4a. X-ray taken during inspiration. The cervical and thoracic sections of the trachea are free. The main bronchi are also free, although the diameter of the left bronchus is somewhat smaller.
46. Expiratory X-ray. The collapse of the thoracic trachea is clearly visible. Collapse also affects the main bronchi and airways distal to the sternum.
Recently, ultrasound has been used to diagnose tracheal collapse (7). When the ultrasound source is located on the neck, it is possible to examine the diameter of the lumen of the cervical trachea and document the dynamics of its changes during the respiratory cycle. In cases where it is impossible to do fluoroscopy, ultrasound is prescribed as the most appropriate method for diagnosing tracheal collapse. Unfortunately, ultrasound examination is usually effective only for cervical tracheal collapse. In addition, it does not allow diagnosing concomitant inflammatory processes and infections of the lower respiratory tract.
In small breed dogs, due to body type or obesity, it can be difficult to detect abnormalities in the tissues of the lungs and heart using radiography. For example, in overweight dogs, fat deposits in the chest and mediastia can give a false impression of infiltrates and lungs. Fat accumulation in the pericardium and reduced lung mobility associated with obesity may mislead the presence of cardiomegaly. Therefore, changes in interstitial density and cardiac size need to be interpreted cautiously in dogs with tracheal collapse. If an animal has a heart murmur, special attention should be paid to examining the contour of the heart - hypertrophy of the left atrium is possible due to its compression by the left bronchus. Using ventroloral radiographs, you can not only examine the condition of the dog’s heart and lungs, but also assess the degree of its obesity. The dog owner should be sure to point out the thick layer of fat covering the chest. This will help convince him of the need to reduce the animal's weight.
Obtaining samples from the respiratory tract
To obtain samples from the respiratory tract, either tracheal lavage or bronchoscopy is used. Both of these procedures require anesthesia. However, it is very useful to carry them out, since it allows you to obtain fluid samples from the lower parts of the respiratory tract for cytological or bacteriological research. Using these methods, it is possible to diagnose respiratory tract infection and assess the contribution of inflammatory reactions to the observed clinical symptoms. Before performing lavage or bronchoscopy, a thorough examination of the upper respiratory tract is necessary. Upper airway obstruction may increase symptoms associated with tracheal collapse. When examining the upper respiratory tract, special attention should be paid to the state of laryngeal function, the length of the soft palate and the absence of swelling of the laryngeal sacs.
To carry out tracheal lavage, it is most convenient to use a transoral approach (see Protocol 1). With this approach, there is less risk of damage to the cartilaginous rings of the trachea and mucosa. To facilitate intubation, it is better to use general anesthesia or strong sedatives. To minimize mucosal irritation, thin sterile intratracheal probes should be used. When inserting a probe into the trachea, care must be taken not to contaminate the resulting samples with bacterial microflora and mucosal cells of the upper respiratory tract. It is not necessary to use a probe cuff for this procedure. The obtained lavage samples should be sent for bacteriological cultivation to identify aerobic bacteria. You can also do cultures for mycoplasma infection.
Interpretation of the results of bacteriological tests is greatly facilitated after cytological examination of the lavage. For example, in healthy dogs, the pharynx is not sterile, and bacteriological examination may reveal bacterial growth in lavage cultures (8) (Table 1). If scaly oral cells and bacteria are detected in the lavage Simonsiella During a histological examination, one can expect the growth of these bacteria and mycoplasmas in bacteriological cultures. Bacteriological culture of lavage from dogs with tracheal collapse usually reveals many bacteria of different species (Table 1). However, the role of bacterial infection in the development of clinical symptoms of this disease is still unclear.
Results of a bacteriological study of the microflora of healthy dogs and dogs with tracheal collapse
Severity of tracheal collapse
| Grade I | The cartilaginous rings of the trachea maintain an almost normal ring structure. There is a slight deflection of the dorsal tracheal membrane into the tracheal lumen, reducing the diameter of this lumen by no more than 25%. |
| Grade II | The cartilaginous rings are flattened. Due to the deflection of the stretched dorsal tracheal membrane, the diameter of the tracheal lumen is reduced by approximately 50%. |
| Grade III | The cartilaginous rings are very strongly flattened. The muscles of the tracheal membrane touch the inside of the rings. The diameter of the tracheal lumen is reduced by 75%. |
| Grade IV | The muscles of the tracheal membrane completely block the lumen of the trachea. In severe cases, the tracheal lumen becomes double. |
To obtain samples of the microflora populating the lower respiratory tract, it is better to use bronchoscopy. Using a bronchoscope, samples can be obtained without the risk of contamination with bacteria from the upper respiratory tract. In addition, bronchoscopy can confirm the diagnosis of tracheal collapse in cases where radiography and fluoroscopy do not allow a firm conclusion. Bronchoscopy makes it possible to directly assess the location and degree of weakening of damaged cartilaginous tracks of the trachea or bronchi (Table 2). which characterize the severity of tracheal collapse, which is especially important when preparing for surgery. Bronchoscopy also allows you to study the dynamics and nature of damage, identify areas of inflammation and irritation of the mucous membranes, confirm or refute the diagnosis of collapse of the thoracic trachea. Thus, bronchoscopy is one of the most effective methods for assessing the role of airway disease in the development of pulmonary failure.
Protocol for obtaining tracheal lavage in dogs
- Give the dog an oxygen mask for pre-oxygenation.
— Administer a sedative to examine the structure and function of the upper respiratory tract. Observe the functioning of the larynx during breathing. Normally, in dogs, the arytenoid cartilages move to the side during inhalation.
— Intubate the animal with a thin, sterile endotracheal tube. During intubation, make sure that the probe does not touch the pharynx when passing into the airway.
— Through a probe to the level of the sternum, insert a thin polypropylene sterile catheter into the respiratory tract (you can use a tube for parenteral nutrition). The length of the catheter should be such that it can reach the level of the 4th rib.
- Inject 4-6 ml of sterile saline solution through the catheter using a syringe. While suctioning the injected fluid, make the dog cough or massage its chest - this will increase the suctioned volume of lavage.
— If necessary, repeat the injection and suction of saline. It is necessary to obtain 0.5-1 ml of lavage. The lavage should be sent for bacteriological (including to determine the presence of mycoplasmas) and cytological examination.
— Before completing the procedure, inject 1 ml of 1% lidocaine solution into the tracheal catheter. This will weaken the cough reflex.
— If necessary, place the patient in an oxygen chamber.
When preparing dogs for airway examination, they should be preoxygenated for 5 minutes. before the start of anesthesia. Anesthesia can be administered in a variety of ways. The purpose of anesthesia in this case is to prevent the cough reflex and damage to the endoscope during bronchoscopy. When choosing an anesthesia method, you should focus on the dog’s general health and the characteristics of the anesthetic used (its side effects). Since most dogs with tracheal collapse are small breeds, it is preferable to use brochoscopes with a diameter of no more than 4.5-5 mm. Sometimes the dog is so small that anesthesia cannot be administered with gaseous anesthetics and the bronchoscope cannot be passed through the intratracheal tube. In this case, when using anesthesia with gaseous anesthetics during bronchoscopic examination of the trachea and lower respiratory tract, the dog should be extubated.
To perform a bronchoscopy, the dog should be placed with its back up and a small pillow placed under the chin. To fix the mouth in an open position during the procedure, 2 large mouth openers are used. First, the larynx and upper respiratory tract are examined using a bronchoscope. After its introduction into the trachea, the degree and dynamics of its collapse are determined (Figure 5). Using marks on the remaining outside part of the bronchoscope, you can determine the length of the collapsed section of the trachea or the number of cartilaginous rings, the structure of which is disturbed. After inserting a bronchoscope into the retrosternal part of the respiratory tract, the main bronchi are examined. Healthy bronchi are open and have a round or elliptical cross-section
(Figure 6). The diameter of the airways should change slightly during breathing, and the amount of secretions in them should be minimal. In dogs with generalized airway collapse, the shape of the lumen of these airways is variable. In addition, the closure of these lumens is clearly visible in them even with non-forced breathing (Figure 7).
Bronchoalveolar lavage (BAL) should be collected from all dogs undergoing bronchoscopy. It is obtained using a bronchoscope and sent for examination to detect infection with bacteria or mycoylases, as well as signs of inflammation. Based on the results of bacteriological and histological examination of the obtained BAL fluid, the animal can be prescribed appropriate antibiotic therapy and/or anti-inflammatory treatment (9). To obtain BAL, the bronchoscope is carefully inserted into the small bronchi and 10-20 ml of sterile saline is injected through its biopsy channel. Suction of the injected fluid can be done manually, with extreme care, or using mechanical suction with a sample trap. It is usually possible to suck out 40-60% of the volume of injected fluid. Normally, BAL contains about 300 leukocytes per ml, of which 70-80% are alveolar macrophages, 5-6% are lymphocytes. 5-6% - for neutrophils and 5-6% - for eosinophils. A sign of an inflammatory reaction is a significant increase in the number of neutrophils. The fact of infection can be established based on the detection of septic neutrophils and the presence of phagocytosed bacteria in the cells.
Figure 5. II-III degrees. A sterile rubber catheter was used to ensure oxygen supply during bronchoscopy. The cartilaginous rings are flattened, resulting in the dorsal part of the trachea (under the mark on the image) being stretched.
Photo courtesy of JeffD. Bay, DVM. MS, University of Missouri, Columbia. USA
Bronchoscopy in dogs with tracheal collapse is a risky procedure. The risk of complications is especially high in obese dogs with increased sensitivity of the trachea. To reduce the risk of complications, the animal should be brought out of anesthesia slowly, providing an oxygen-enriched environment. Before removing the bronchoscope, 1 ml of a 1% lidocaine solution can be injected into the distal trachea. This will weaken the cough reflex.
Drug treatment
If a dog exhibits severe dyspnea due to airway obstruction, the stress of the diagnostic examination should be kept to a minimum. In such cases, to remove the animal from a dangerous state, you need to place it in an oxygen chamber and use mild sedatives. For example, subcutaneous administration of butophanol (0.05-1 mg/kg) and acepromazine (0.01-0.1 mg/kg) every 4-6 hours can not only calm the dog, but also stop its coughing attack. It should be noted that the use of these drugs in combination requires some caution, as it may cause a sharp decrease in blood pressure. At the beginning of use, the minimum dosage of drugs should be used to determine the sensitivity of a given animal to them. If no undesirable consequences occur, the dosage can be increased in the future if necessary. If your dog has severe inflammation of the trachea or swelling of the larynx, he should be given a single dose of a short-acting corticosteroid that has an anti-inflammatory effect.
Long-term therapy for tracheal collapse in dogs should be aimed at weakening those factors that can provoke an increase in the clinical symptoms of the disease. Unfortunately, there are no specific methods for treating metabolic disorders in the cartilage tissue of tracheal rings, so the risk of exacerbation of the disease in a sick dog remains throughout its life. If a respiratory tract infection is detected, antibiotic therapy should be prescribed. The choice of antibiotics is made on the basis of determining the sensitivity of the patient's inoculated microflora to them. If a Mycoplasma infection is detected, antibiotics that are effective against microorganisms that lack a cell wall should be used. The most effective in this case are doxycycline, chloramphenicol and enrofloxacin. To sterilize the respiratory tract, a 7-10-day course of antibiotics is usually sufficient, but in the presence of pneumonia, the duration of antibiotic therapy can be from 3 to 6 weeks.
With severe tracheitis, short-term treatment with corticosteroids is necessary. Typically, the patient is administered prednisone or prednisolone in doses of 0.5 mg/kg/day for 3-7 days. If a dog has chronic bronchitis due to tracheal collapse, a longer course of corticosteroid therapy is prescribed. The drugs are used in large dosages. After the inflammation is relieved and the infection is eliminated, cough medications are prescribed. Its suppression is necessary to break the cycle of repeated airway damage. Typically, cough suppression in dogs with tracheal collapse requires the use of narcotics. Cough can be effectively suppressed with hydrocolon (0.22 mg/kg 2-3 times a day) or butorphanol (0.55-1.1 mg/kg if necessary) used per os(10). At the beginning of the course, the dosage of these drugs is selected for each dog individually in such a way as to achieve maximum suppression of cough. Noreceptors are not bronchodilators, but they cause dilatation of the small airways and facilitate air exchange in them during exhalation. As a result, the likelihood of thoracic tracheal collapse is reduced. Special pharmacokinetic studies of various forms of theophylline have shown that two long-acting theophylline preparations produced by different companies ensure the maintenance of a sufficiently high concentration of the drug in the blood of dogs for a long time. Regular forms of theophylline may also be effective, but their effectiveness is much lower than that of the long-acting preparations mentioned. For tracheal collapse in dogs, beta-adrenergic receptor agonists are also used: terbutaline (1.25-5 mg/kg<гол- 2-3 раза вдень) и альбутерол (50 мкг/кг 3 раза в день). Следует помнить, что применение бронхорасширяющих средств любого типа может привести к побочным эффектам, например, повышенной нервозности и возбудимости животных, тахикардии, желудочно-кишечным расстройствам.
All dogs with tracheal collapse require nutritional therapy. Reducing body weight, for example, significantly reduces the load on the respiratory system. To achieve this goal, animals are usually switched to ready-made low-calorie diets, which provide approximately 60% of the energy needs of healthy dogs. The ideal rate of weight loss (2-3% of body weight per week) allows the owner to quickly normalize the dog's weight. It is also useful to gradually increase the animal's physical activity - this makes it easier and faster to achieve normal body weight. It should be noted that it is better to reduce physical activity to a minimum in hot and humid weather, and replace the collar with a harness. This will avoid a sudden exacerbation of the disease.
Surgery
In case of collapse of the cervical trachea, prosthetics of the affected cartilage rings is effective. Surgical intervention is indicated in cases where therapeutic treatment is ineffective or when animals experience weakened conditioned reflexes and fainting due to breathing problems. Surgical intervention significantly weakens clinical symptoms: cough disappears, breathing becomes freer. One study found that dog owners were generally satisfied with the outcome of surgery, even if postoperative laryngeal paralysis required a tracheostomy.
For dogs with upper airway obstruction, surgical removal of the cause of the obstruction is necessary. For example, shortening the soft palate and releasing the arytenoid cartilage of the larynx has been shown to alleviate clinical symptoms in tracheal collapse.
Tracheal collapse is common in small breed dogs and requires long-term treatment. Sick animals are advised to reduce body weight and use anti-cough medications. In each specific case, it is also important to identify and eliminate concomitant diseases of the upper and lower respiratory tract, complicating the course of tracheal collapse.
is a bronchoscopic method of obtaining a wash from the surface of the smallest bronchi (bronchioles) and alveolar structures of the lungs for cytological, microbiological, biochemical and immunological studies. Sometimes used for medicinal purposes to cleanse inflamed airways from excess secretory purulent contents.
In veterinary practice, we use this diagnostic method to conduct a cytological analysis of the obtained material, as well as for bacteriological examination. Thus, the diagnosis includes a qualitative/quantitative assessment of the cells that make up the bronchial mucus (for example, eosinophilic or neutrophilic inflammation predominates in the patient). Also, the resulting material is sown on nutrient media in order to determine which pathogen colonizes the surface of the bronchi and the sensitivity of the found microorganism to antibiotics is titrated.
When exactly is the study carried out?
Very often, animals with a history of chronic coughing attacks (the onset of symptoms was noted more than 1 month ago), periodically occurring noisy breathing, attacks of suffocation, and so on are brought to see a veterinarian.
Interestingly, neither a chest x-ray nor a complete blood count or nasal swabs can help differentiate feline asthma from bronchitis. Changes on a chest x-ray are nonspecific: as a rule, they are the same type of enhancement of the bronchial or broncho-interstitial pattern. As for washings from the surface of the upper respiratory tract, it should be remembered that the microbial landscape at the level of bronchioles and mucous membranes of the nasal passages is very different, and when mycoplasma is detected on the surface of the conjunctiva of the eye, we have no right to say that this pathogen causes irreversible changes at the level of the bronchi.
In dogs, chronic cough can also be diagnosed using a BAL. Thus, dog cough can be a symptom of very different diseases. For example, infectious and idiopathic bronchitis show the same changes on chest x-ray, but require completely different treatment. A very valuable method for selecting therapy for the development of severe pneumonia that is refractory to antibiotic treatment in puppies and young dogs. After all, bacteriological research allows you to accurately determine which pathogen is resistant to the standard antibacterial regimen. It is also possible to accurately and quickly select the necessary and specific antibiotic.
In addition, using the method, we can exclude eosinophilic pulmonary infiltration syndrome, which develops in young animals and requires aggressive steroid therapy to stop attacks, while steroids prescribed for an active bacterial process can kill the patient.
How exactly is the research carried out?
To collect swabs from the surface of the bronchi, we use the bronchoscopy method. A bronchoscope is inserted approximately to the level of the 2-3rd order bronchi, which makes it possible to examine the surface of the bronchial tree, as well as to exclude possible foreign objects that have entered the respiratory tract, for example, during active running. Next, using a bronchoscope, we inject a small volume of sterile solution and very quickly take it back. The resulting material is examined under a microscope and plated on special media.
Method safety
Bronchoalveolar lavage is considered safe, very effective in making a diagnosis, and often has a therapeutic effect. Characteristically, the cough disappears for a short time after the procedure. Requires minimal anesthesia (sedation). When carrying out specific preparation, it has no side effects.
Why do this research?
It is very important to understand that a chronic, prolonged, progressive cough often indicates the development of irreversible, severe bronchopulmonary problems, which, even with well-chosen therapy, may not respond well to treatment. Feline asthma has a high risk of sudden death. So, a timely diagnosis and selected therapy can get rid of problems at an early stage and significantly improve the quality of life of your pet.
Veterinarian
Filimonova D.M.
