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Biochemical and cytological analysis of
bronchoalveolar lavage (BAL) fluid and
effects on arterial blood gases in dogs with
lower respiratory airway disease
R. GONUL1*, L. KOENHEMSI1, M.E. OR1, A. UYSAL1, K. SONMEZ2, A. GUREL2, A.F. BAGCIGIL3, N.Y.
OZGUR3, H. YARDIBI4, K. ALTUNATMAZ5
Department of Internal Medicine, Veterinary Faculty, Istanbul University, 34 320 Avcilar, Istanbul, TURKEY.
Department of Pathology, Veterinary Faculty, Istanbul University, 34 320 Avcilar, Istanbul, TURKEY.
Department of Microbiology, Veterinary Faculty, Istanbul University, 34 320 Avcilar, Istanbul, TURKEY.
4
Department of Biochemistry, Veterinary Faculty, Istanbul University, 34 320 Avcilar, Istanbul, TURKEY.
5
Department of Surgery, Veterinary Faculty, Istanbul University, 34 320 Avcilar, Istanbul, TURKEY.
1
2
3
*Corresponding author: [email protected]
SUMMARY
The aims of this study were to investigate the effects of BAL collection on
the respiratory function in healthy dogs and in dogs suffering from lower
airway respiratory diseases and to consider the potential diagnostic value of
some biochemical and cytological parameters measured in BAL fluids. For
that, endoscopy and BAL collection were performed under anaesthesia
induced with medetomidin (40 μg/kg IM) and propofol (1 mg/kg IV) in
dogs with pulmonary disorders (n = 30) and in healthy dogs (n = 10). The
evaluation of the respiratory function was made throughout determination of
blood gas and acid-base balance before anaesthesia and directly after BAL
fluid sampling. In parallel, the effects of the anaesthesia alone on the respiratory system were also assessed in healthy dogs (n = 10) which were not
submitted to the BAL collection. The anaesthesia protocol instead of the
BAL collection by itself induced hypoventilation and low O2 exchange between alveoli and arteries as evidencing by significant decreases of PaO2 and
O2Sat and significant increases of PaCO2 and arterial-alveolar PO2 gradient
(A-aPO2). In diseased dogs, PaO2/O2Sat and the A-aPO2 were initially
affected and under anaesthesia, variations of O2Sat, PaCO2 and base deficit
were aggravated whereas changes in PaO2 and A-aPO2 were less pronounced compared to healthy controls. Significant increases of LDH, ALT and
ALP activities and of urea concentrations in BAL fluids from diseased dogs
coupled to a high cellularity (epithelial and inflammatory cells) and positive bacterial isolation in some cases have confirmed the inflammatory and/or
infectious origin of the pulmonary diseases. Although biochemical and cytological analysis of the BAL fluids can help to characterize the pulmonary
disease, its collection under anaesthesia may require some attention in diseased dogs because of its direct effects on respiratory function.
Keywords: Dog, bronchoalveolar lavage, arterial blood
gases, anaesthesia, biochemistry, cytology.
RÉSUMÉ
Analyse biochimique et cytologique du liquide de lavage bronchoalvéolaire (LBA) et effets sur les gaz sanguins chez les chiens atteints
d’une maladie des voies aériennes basses
Cette étude a eu pour objectifs d’évaluer les effets directs d’un lavage bronchoalvéolaire sur la fonction respiratoire chez des chiens sains ou soufrant de
maladie pulmonaire et de considérer la valeur diagnostique potentielle de
divers paramètres biochimiques et cytologiques mesurés dans le liquide de
lavage broncho-alvéolaire (LLBA). Pour cela, une endoscopie et un lavage
broncho-alvéolaire ont été réalisés sous anesthésie [médétomidine (40 μg/kg
IM) et propofol (1 mg/kg IV)] chez des chiens malades (n = 30) et sains (n = 10).
La fonction respiratoire a été évaluée par détermination des gaz sanguins et
de l’équilibre acido-basique avant l’anesthésie et directement après le LBA.
Les effets sur le système respiratoire de l’anesthésie seule ont également été
appréhendés sur des chiens sains (n = 10) non soumis à un lavage bronchoalvéolaire. Le protocole d’anesthésie, plutôt que le lavage par lui-même, a
induit une hypoventilation et une diminution des échanges en O2 entre les
alvéoles et les artères (diminutions significatives de PaO2 et O2Sat et augmentations significatives de PaCO2 et du gradient en oxygène artério-alvéolaire
(A-aPO2)). Chez les chiens malades, PaO2/O2Sat et A-aPO2 étaient initialement modifiés et sous anesthésie, les variations en O2Sat, PaCO2 et le
déficit basique se sont aggravés alors que les modifications de la PaO2 et de
l’A-aPO2 ont été moins importantes que chez les sujets contrôles. L’origine
inflammatoire et/ou infectieuse des maladies pulmonaires a été confirmée
par des augmentations significatives des activités LDH, ALT, PAL et des
concentrations en urée dans les liquides de lavage chez les chiens malades
associées à une forte cellularité (cellules épithéliales et inflammatoires) et
dans quelques cas à une isolation bactérienne positive. Bien que les analyses
biochimiques et cytologiques des liquides de lavage puissent aider à la
caractérisation de la maladie pulmonaire, son recueil sous anesthésie
requiert une attention particulière chez les malades en raison de ses effets
directs sur la fonction respiratoire.
Mots clés : Chien, lavage bronchoalvéolaire, gaz sanguins
artériels, anesthésie, biochimie, cytologie.
Introduction
Bronchoscopy and bronchoalveolar lavage (BAL) may be
used for the diagnosis and treatment of respiratory diseases
in humans and small animals [3, 6-8, 13, 14]. BAL is a reliable
Revue Méd. Vét., 2010, 161, 5, 233-238
procedure which helps in diagnosing the disorders of the
respiratory system, and in the studies performed, researchers
have analyzed the BAL fluid with regard to enzyme, cytology,
culture and histopathology [2, 5-8, 12-14, 18, 20, 21]. Despite
its widespread use, an agreement has not been achieved on
234
the laboratory techniques that are used, the fluid volume and
the technical issues such as various lavage applications [17].
For this reason, there are various reference values for dogs
and the results of studies with various methods make the
comparison difficult [17].
Detection of alterations in enzyme activities and identification of the cellular components in BAL fluid are useful for
the diagnosis of pulmonary inflammations and lacerations
[9, 12]. Epithelial and inflammatory cells in BAL fluid are
the most sensitive indicators of the inflammatory response
and they evidence pathological alterations in pulmonary
parenchyma. Similarly, detection of cytoplasm and membrane enzymes in the acellular portion of the BAL fluid is an
indicator of cell death or membrane damage [9, 12].
Furthermore, despite the fact that studies related to immunoglobulins in the respiratory tract have been performed to
study local immune mechanisms in chronic bronchitis, no
article on dogs has been available. Moreover, the effects of
BAL applications on blood gases in dogs with respiratory
tract disorders have not been sufficiently studied [18].
Accurate analysis of blood gases facilitates the clinical
evaluation of metabolic acid-base and respiratory system disorders [10, 16]. It is also helpful in making a proper diagnosis
and plan of treatment by enabling the distinction of ventilation
(carbon dioxide) and oxygenation (oxygen) problems [16].
In this way, the arterial-alveolar PO2 gradient (A-aPO2) can
be used to evaluate the degree of pulmonary disorder [16].
The arterial-alveolar PO2 gradient (A-aPO2) increases in
right to left shunt, low mixed venous oxygen saturation, ventilation/perfusion non-conformance, and diffusion insufficiencies [19]. However, researchers have reported a decrease
of arterial oxygen pressure following BAL in cats, dogs and
humans [7, 17, 18]. Besides, RAJAMAKI et al. [18] have
reported that although the effects of the BAL procedure on
blood gases have been studied in healthy animals, they have
not been studied in dogs with respiratory tract disorders, and
for this purpose, they have studied dogs in which pulmonary
eosinophilia had been detected. On the other hand, the cardiopulmonary effects of anaesthetic drugs that are used are
not completely known [4].
The aims of the present study are firstly to compare blood
gases analysis and oxygen saturation, acid-base balance and
electrolyte concentrations between dogs with lower respiratory
tract disorders and apparently clinically healthy dogs,
secondly to evaluate the diagnostic values of some biochemical markers (Total protein, urea, creatinine, Ca/P and enzyme
LDH, ALP, ALT and GGT activities, immunoglobulins (IgA,
IgG and IgM) and cellular constituents (bacteriological and
various cell populations) in BAL fluid and thirdly to investigate the
effects of anaesthesia with medetomidin and propofol during
endoscopy application on blood gases in healthy and sick dogs.
Materials and Methods
ANIMALS AND PROTOCOL DESIGN
The study was conducted in accordance with the ethical
committee principles and with the approval of the Ethical
GONUL (R.) AND COLLABORATORS
Committee of the Veterinary Faculty of Istanbul University
(2006-39).
A total of 30 sick dogs of various breeds and ages, and of
both sexes have been brought to the internal medicine clinic,
Veterinary Faculty, Istanbul, Turkey for respiratory tract
complaints. Diagnosis of lower respiratory tract disorders
such as chronic broncho-pneumonia was based on clinical
and radiological examinations. This group constituted the
study group (BAL-diseased group). Additionally, twenty
dogs without any respiratory tract disorder throughout routine
clinical examination were divided into 2 control groups: the
BAL characteristics were evaluated in one group, named
BAL-control group (n = 10) and in the other, called
Anaesthesia-control group (n = 10), blood gas analysis was
performed under anaesthesia.
After sedation with medetomidin (Domitor, Orion Pharma,
Finland, 40 µg/kg IM), and anaesthesia induction with propofol (Fresenius Kabi AB, Sweden, 1 mg/kg IV) eventually
re-administered with the same dosage when required, bronchoscopy and BAL were applied to the BAL-diseased and
BAL-control dogs accordingly to the previous described
technique [2, 6, 17, 18]. Additional oxygen was not administered to the dogs during the procedure and sedation was
reversed using atipamezole (Antisedan, Orion Pharma,
Finland, 200 µg/kg IM). The anaesthesia reversion with atipamezole was rapid and complete within 5-10 minutes.
Furthermore, 2 femoral arterial blood samples, one before
sedation, the other, 5 minutes after BAL application but
before anti-sedation, were obtained from each animal from
BAL-diseased and BAL-control groups in accordance with
the described technique [18].
After applying the above-mentioned anaesthesia protocol
to the Anaesthesia-control group, laryngeal inspection was
performed and dogs were intubated. Arterial blood samples
were collected as previously described before anaesthesia
and 10 minutes after intubation.
BIOCHEMICAL, CYTOLOGICAL AND BACTERIOLOGICAL
ANALYSES
The BAL fluid samples were separated for biochemical,
bacteriological and cytological analyses in accordance with
the described technique [2, 6, 12].
The different biochemical markers were measured in the
BAL fluids by spectrophotometry using commercial kits
(Total proteins, urea, creatinine, Ca, P, LDH, ALP, ALT, and
GGT, Spinreact kits, Spinreact SA., SPAIN).
Cell populations present in BAL fluids were identified
according to the following technique: after a first grossly
evaluation and centrifugation (716g, 5 minutes at room temperature), they were left in rack about 1-2 minutes in order to
let the precipitate to settle. The fluid supernatant was decanted completely by gently inverting the tube. Eight smears
were made from each concentrated sample and for each
smear 20 µL supernatant were used. After air-drying them at
room temperature about half an hour, smears were stained
simultaneously (2 with Gram’s, 2 with Diff-Quick, 2 with
Revue Méd. Vét., 2010, 161, 5, 233-238
BRONCHOALVEOLAR LAVAGE AND BLOOD GASES IN DOGS
Wright’s and 2 with May-Grünwald Giemsa stains). Each
smear was inspected with light microscope and evaluated.
Cell population were assessed by counting cell numbers for
each types of cell groups in random 10 areas under 40X
magnification and calculating their percentage reported to
the total number of cells [2, 12-14].
The bacteriological examination of BAL fluids was performed according to the technique of PADRID and Mc KERNAN
[15].
The immunoglobulin concentrations were determined
using dog IgG, IgM, IgA ELISA quantification kits (Bethyl
Lab. Inc., Montgomery, TX, USA) whose the detection
limits were 7.8 - 500 μg/L for IgG and 15.6 - 1 000 μg/L for
IgA and IgM. Each BAL fluid was diluted to 1:5, 1:10, 1:100
and 1:1000 for IgG and IgM measurements and to 1:5, 1:10
and 1: 100 for IgA determination in order to conform to the
kit limits. All samples were analysed twice.
Variations in blood gases values, acid-base balance and
some electrolyte concentrations were analysed in accordance with the technique using the IRMA TruPoint® (ITC,
USA) blood gases analyzer. The arterial-alveolar PO2 gradient (A-aPO2) was formulated according to sea level and
room temperature conditions as follows [1, 22]:
A-aPO2 (mmHg) = FiO2(BP - pH2O) - 1.25PaCO2 - PaO2
or
A-aPO2 (mmHg) = 150 - 1.25PaCO2 - PaO2
where FiO2 was the fraction of inspired oxygen, BP the
barometric pressure, pH2O the partial pressure of water at
body temperature, PaCO2 the partial pressure of CO2 and
PaO2 the partial pressure of O2.
Parameters
pH
Beb (mmol/L)
Beecf (mmol/L)
HCO3- (mmol/L)
TCO2 (mmol/L)
PaCO2 (mmHg)
PaO2 (mmHg)
O2Sat.(%)
tHb (g/L)
Hct (%)
A-aPO2 (mmHg)
Na (mmol/L)
K (mmol/L)
iCa (mmol/L)
Anaesthesia-control group
Before
During
anaesthesia
anaesthesia
7.43 ± 0.02a
7.37 ± 0.02b
a
-1.25 ± 1.15
-2.15 ± 1.17b
235
STATISTICAL ANALYSIS
The statistical analysis was performed using independent
samples t-test for comparison between groups and paired
samples t-test for comparison within the groups. The differences were considered as significant when P value was less
than 0.05.
Results
CLINICAL SIGNS
Fever, loss of appetite, nasal discharge, coughing and
abnormal pulmonary auscultation findings were observed in
dogs with respiratory system disorders, whereas no signs of
pulmonary or other disorders were detected in healthy dogs.
No additional health disorder was detected in dogs throughout the study. Besides, mucosa hyperaemia and increased
secretions were evidenced in sick dogs during endoscopy.
BLOOD GAS ANALYSIS AND ACID-BASE EQUILIBRIUM
As reported in Table I, the anaesthesia protocol in the 2
control groups (Anaesthesia- and BAL-control groups) has
induced significant decreases of pH values (P < 0.05), partial
pressure of oxygen (PaO2) and oxygen saturation (O2Sat) (P
< 0.05 in anaesthesia-control group and P < 0.001 in BALcontrol group). By contrast, significant increases of partial
BAL-control group
Before
During
anaesthesia
anaesthesia
7.44 ± 0.06a
7.40 ± 0.01b
BAL-diseased group
Before
During
anaesthesia
anaesthesia
7.40 ± 0.01a
7.30 ± 0.01b
a
-1.08 ± 0.33
-3.14 ± 0.59b
a
-1.75 ± 0.34
-3.38 ± 0.60b
-2.23 ± 1.13
21.83 ± 0.75
22.80 ± 0.75a
33.23 ± 1.27a
111.41 ± 4.23a
97.86 ± 0.27a
122.8 ± 10.9a
36.11 ± 3.20a
-2.94 ± 0.50a
-3.01 ± 1.24
21.93 ± 0.98
23.05 ± 0.98b
38.11 ± 1.27b
88.55 ± 7.10b
95.35 ± 1.07b
135.5 ± 7.8b
39.81 ± 2.28b
13.82 ± 1.30b
-0.61 ± 0.57
-1.40 ± 0.60
22.43 ± 0.50a
23.12 ± 0.53a
33.20 ± 1.40a
111.60 ± 3.10a,A
97.94 ± 0.32a,A
133.8 ± 6.9a
39.30 ± 2.00a
-3.10 ± 0.70a,A
-0.65 ± 1.03
-0.92 ± 1.03
23.79 ± 0.74b
24.95 ± 0.74b
38.89 ± 1.30b
84.79 ± 3.83b
93.60 ± 2.79b
150.4 ± 5.7b
44.28 ± 1.68b
26.60 ± 1.16b
22.51 ± 0.29
23.57 ± 0.30
35.23 ± 0.79a
72.83 ± 1.79a,B
95.52 ± 0.18a,B
130.8 ± 4.0a
38.49 ± 1.18a
24.00 ± 2.10a,B
22.13 ± 0.43
23.34 ± 0.42
41.55 ± 0.75b
63.29 ± 2.21b
90.30 ± 1.61b
142.4 ± 3.3b
36.04 ± 0.97v
34.78 ± 3.20b
146.48 ± 0.89
4.21 ± 0.15
1.41 ± 0.07a
146.03 ± 0.64
4.44 ± 0.17
1.52 ± 0.03b
145.80 ± 2.00
4.17 ± 0.17
1.44 ± 0.50a
145.85 ± 1.79
3.96 ± 0.13
1.53 ± 0.05b
147.07 ± 1.17
4.29 ± 0.10
1.34 ± 0.02
146.22 ± 1.03
4.42 ± 0.78
1.38 ± 0.03
Beb: Base excess of blood; Beecf: Base excess of extra cellular fluid; TCO2: Total carbon dioxide; PaCO2: Partial pressure of carbon dioxide; PaO2: Partial
pressure of oxygen; O2Sat.: Oxygen saturation; tHb: total hemoglobin; Hct: Haematocrit; A-aPO2: Arterial-alveolar PO2 gradient; iCa: ionized calcium.
Different superscripts a,b in the same line indicate significant differences (P < 0.05) within the same group (effects of anaesthesia or BAL collection or
Disease) and different superscripts A,B in the same line indicate significant differences (P < 0.05) between the BAL-control and BAL-disease groups.
TABLE I : Arterial blood gas and acid-base equilibrium in Anaesthesia-control (n = 10), BAL-control (n = 10) and BAL-diseased (n = 30)
dog groups. Anaesthesia was performed with association of medetomidin plus propofol. Results are expressed as mean ± standard error.
Revue Méd. Vét., 2010, 161, 5, 233-238
236
pressure of carbon dioxide (PaCO2), Total carbon dioxide
(TCO2), haematocrit (Hct), Total hemoglobin (tHb), ionized
calcium (iCa) (P < 0.05) and arterial-alveolar PO2 gradient
(A-aPO2) (P < 0.01) were observed during anaesthesia in
both 2 groups. When the responses of these groups to anaesthesia were compared, the increase of A-aPO2 and the
decrease of the PaO2 appeared more marked in the BALcontrol group (A-aPO2 variations: + 29.70 mmHg and PaO2
variations: - 26.81 mmHg) than in the Anaesthesia-control
group (+ 16.76 mmHg and - 22.86 mmHg, respectively).
Compared to the BAL-controls, the PaO2 and O2Sat values
before anaesthesia were significantly depressed (P < 0.001)
and PaCO2 and arterial-alveolar PO2 gradient (A-aPO2)
values significantly enhanced (P < 0.05) in BAL-diseased
dogs. Furthermore, the anaesthesia-induced variations of pH,
O2Sat, PaCO2 and Beb (Base excess in blood) were amplified in the diseased animals whereas changes in all other
parameters (except of Na and K concentrations which remained
roughly constant during anaesthesia in all 3 groups) were on
the contrary alleviated (PaO2, Hb, A-aPO2,) or abolished
(TCO2, HCO3-, Beecf, Hct, iCa).
GONUL (R.) AND COLLABORATORS
BAL-control
group
BAL-diseased
group
Total Protein (g/L)
1.1 ± 0.4
1.3 ± 0.2
Urea (mmol/L)
1.10 ± 0.03a
1.30 ± 0.03b
Creatinine (μmol/L)
7.4 ± 0.5
8.5 ± 0.5
Ca (mmol/L)
1.10 ± 0.04
1.10 ± 0.03
P (mmol/L)
0.100 ± 0.003
7.4 ± 0.6a
0.200 ± 0.010
12.7 ± 0.4b
LDH (U/L)
24.5 ± 1.0a
14.0 ± 0.3a
55.1 ± 2.8b
22.7 ± 0.6b
GGT (U/L)
7.8 ± 0.2
7.2 ± 0.1
IgG (mg/L)
20 ± 10
100 ± 100
IgM (mg/L)
2±1
7±3
IgA (mg/L)
20 ± 6
8±4
Neutrophil (%)
6.5 ± 5.7a
55.5 ± 13.3b
Eosinophil (%)
2±2
5.4 ± 5.2
Macrophages (%)
74.07 ± 6.57a
24.3 ± 16.9b
Biochemistry
ALT (U/L)
ALP (U/L)
Cytology
BIOCHEMICAL AND CYTOLOGICAL ANALYSIS OF THE
Lymphocyte (%)
14.35 ± 4.12
6.34 ± 10.38
BAL FLUID
Epithelial cells (%)
1.24 ± 0.08a
4.1 ± 0.4b
The Table II presents the biochemical and cytological findings
of the BAL fluids collected from dogs with lower respiratory
tract disorders and from healthy dogs. Whereas the total protein
and calcium concentrations and the GGT activity in the BAL
fluids were similar between the 2 groups, the other investigated parameters tended to increase (creatinine and phosphorus
concentrations) or significantly increased (urea concentrations
and ALT activity (P < 0.01), ALP and LDH activities (P <
0.001)) in diseased dogs. As far as immunoglobulins were
concerned, the IgG and IgM concentrations appeared to be
augmented in dogs with respiratory diseases compared to
controls but not significantly because of the great dispersion
of values.
The cytological analysis of the BAL fluids revealed significant and marked increases of the counts of inflammatory
neutrophil leukocytes and macrophages as well as epithelial
cells compared to healthy dogs. Furthermore, the proportion
of bacteriological positive BAL fluids was 43.33% and cocci
and/or rods (mainly E. coli, Staphylococcus epidermidis,
Klebsiella pneumoniae, Mycoplasma spp. and Enterobacter
cloaca) were also isolated from BAL fluids from diseased
dogs while no micro-organism was found in healthy controls
(Table III).
Discussion
In the present study which entailed a detailed endoscopic
examination of dogs with lower respiratory system disorders,
changes in blood gases analysis, acid-base balance and in some
electrolyte concentrations were detected before and after
endoscopy. In addition, extensive biochemical, cytological,
bacteriological and immunological evaluation of collected
ALT: Alanine aminotransferase; ALP: Alkaline phosphatase; LDH:
Lactate deshydrogenase; GGT: Gamma-glutamyl Transferase.
Different superscripts a,b in the same line indicate significant differences
(P < 0.01).
TABLE II: Biochemical and cytological parameters of the BAL fluid
collected under anaesthesia (medetomidin plus propofol) from
healthy dogs (BAL-control group, n = 10) or from dogs with lower
respiratory airway diseases (BAL-diseased group, n = 30). Results
are expressed as mean ± standard error.
BAL-control BAL-diseased
group
group
Germs
E. coli
0
4
Staphylococcus epidermidis 0
2
Klebsiella pneumoniae
0
2
Mycoplasma spp
0
2
Enterobacter cloaca
0
2
0
1
0/10
13/30
Others
Total
TABLE III: Bacteriological analysis of the BAL fluid collected under
anaesthesia (medetomidin plus propofol) from healthy dogs (BALcontrol group, n = 10) or from dogs with lower respiratory airway
diseases (BAL-diseased group, n = 30).
bronchoalveolar lavage fluid was performed from patients
with respiratory tract disorders and the effects on blood gases
of anaesthesia induced by the combination medetomidin plus
propofol were examined in healthy and diseased dogs.
Revue Méd. Vét., 2010, 161, 5, 233-238
BRONCHOALVEOLAR LAVAGE AND BLOOD GASES IN DOGS
Dogs with lower respiratory tract disorders exhibited
symptoms such as fever, anorexia, depression, nasal discharge,
coughing, expectoration, tracheal sensitivity and abnormal
pulmonary auscultation findings, similar to those reported by
other researchers [11, 12]. BAL applications, similar to those
reported by other researchers [13, 17] did not cause any additional difficulties in healthy dogs or in those with respiratory
tract disorders. In agreement with previous reports [9, 12],
epithelial and inflammatory neutrophils and macrophages in
the current study were increased and various bacterial agents
such as E. coli, Staphylococcus epidermidis, Klebsiella
pneumoniae, Mycoplasma spp. and Enterobacter cloaca
have grown in the BAL fluids in dogs with respiratory tract
disorders, corroborating the inflammatory and /or the infectious nature of some respiratory diseases. Furthermore, it
was reported that cellular enzymes in BAL fluid can be used
as important markers of cellular integrity or cellular damage,
and total protein and urea concentrations can be used to detect
alterations in vascular permeability and permeability of the
membranes of the respiratory system [9, 12]. Accordingly,
urea concentration and ALT, LDH and ALP activities in the
BAL fluid of patients with respiratory tract disorders were
found to be statistically significantly increased. PADRID et al.
[14] reported low concentrations of IgG (<0.01 mg/ml) in
BAL fluid from healthy cats and that they failed to detect
IgM while detecting IgA. In the present study, the immunoglobulin concentrations in BAL fluid of healthy dogs were
also very low (20 ± 10 mg/L, 2 ± 1 mg/ml and 20 ± 6 mg/ml,
for IgG, IgM and IgA respectively). Although not significantly because of great value dispersion, increases of IgG
and IgM concentrations were observed in sick animals in the
present study, suggesting probably local defence reactions.
A PaO2 lower than 80 mmHg, indicates hypoxemia [11,
16, 19]. The difference between alveolar and arterial O2
pressures, called alveolar-arterial gradient (A-aPO2), indicates
tissue oxygenation and is usually below 15 mmHg [1, 16,
19]. In this study, dogs with pulmonary disorders exhibited
significantly decreased PaO2 and O2Sat and a dramatically
increased A-aPO2 compared to healthy dogs, indicating
hypoxemia and pulmonary oxygenation deficit, respectively.
Moreover, after endoscopy and BAL application, these parameters were deeply depressed and the base deficit increased
in the diseased group. These alterations reflect ventilation
problems induced by various diseases but also by the BAL
procedure itself which includes sedation and decumbency
[16-18]. In this way, it was previously observed decrease of
PaO2 and increase of PaCO2 induced by medetomidin and
propofol anaesthesia [4, 5]. In agreement with that, the combination of medetomidin and propofol used in the present
study clearly induced strong diminutions of PaO2, O2Sat
and the base deficit coupled to augmentations of PaCO2,
TCO2 and A-aPO2. In parallel, the haematocrit values and
the haemoglobin concentrations were significantly enhanced
in anaesthesia-controls, probably for compensating the oxygenation deficit. Although RAJAMAKI et al. [17] also reported
that these changes could be more pronounced in dogs with
pulmonary tract diseases in a first study, the same researchers
found that variations of PaO2 and A-aPO2 were similar in
dogs with pulmonary eosinophilia and in healthy dogs [18].
In this study, variations of O2Sat, PaCO2, pH and base deficit
were exacerbated after BAL application in dogs with lower
Revue Méd. Vét., 2010, 161, 5, 233-238
237
airway respiratory diseases whereas the intensity of tissue
oxygenation evidencing by PaO2 and arterial-alveolar PO2
gradient (A-aPO2), already depressed, and the red blood
cells mobilisation reflecting by haematocrit and haemoglobinemia were less affected by endoscopy and BAL collection in
the diseased animals than in the healthy controls. Consequently,
it would be out of interest to pay more attention and to investigate the oxygen saturation in respiratory disease dogs.
As a conclusion, the biochemical, cytological and bacteriological analyses of BAL fluids can be useful for diagnosis
and prognostic of the lower airway respiratory disorders in
dogs: marked increases of LDH, ALT and ALP activities
coupled to increased cellularity (inflammatory and epithelial
cells) confirms pulmonary inflammation or damage, variations
of protein and urea concentrations indicate alterations in vascular
and respiratory permeability, increases of immunoglobulin
concentrations evidences local and specific defence reactions
and identification of some microorganisms can lead to an
accurate diagnosis. Additionally, the detection of blood gases
values and namely of PaO2, O2Sat, PaCO2 and arterialalveolar PO2 gradient (A-aPO2), helps in the follow-up of
the disease. Nevertheless, despite the comfort of medetomidin
and propofol anaesthesia easily reversed with antipamezole,
as the anaesthesia protocol and the BAL procedure directly
alter gas exchange and the acid-base equilibrium, the blood
gas analysis would be helpful in the surveillance of dogs with
lower airway pulmonary disorders in order to limit disease
aggravation.
Acknowledgement
The authors wish to acknowledge Research Fund of
Istanbul University for supporting this research (Project
number: 596/15122006).
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