Blood gas analysis in dogs with heartworm caval syndrome

Blood gases and cardiopulmonary function were analyzed in 67 dogs with heartworm (HW) caval syndrome (CS) and 19 HW-free dogs. Arterial oxygen tension (PaO2) was 91.5 +/- 7.3 mmHg in the HW-free dogs, 74.9 +/- 14.3 mmHg in 46 dogs that subsequently survived surgical HW removal (surviving dogs) and 64.6 +/- 14.7 mmHg in 21 dogs which later died or were euthanatized following surgical treatment (nonsurviving dogs). PaO2 levels less than 60 mmHg were detected in 30.4% and 38.1% dogs in the surviving and nonsurviving groups, respectively. Arterial carbon dioxide tension (PaCO2) was 35.8 +/- 4.9 mmHg in the HW-free dogs, 30.7 +/- 5.6 mmHg in the surviving dogs, and 28.8 +/- 6.2 mmHg in nonsurviving dogs. PaO2 (p < 0.01) and PaCO2 were lower (p < 0.01) and the alveolar-arterial oxygen difference (AaDO2) was higher (p < 0.01) in CS dogs than in HW-free dogs. PaO2 was lower (p < 0.01) and AaDO2 was larger (p < 0.01) in the nonsurviving dogs than in the surviving dogs. Arterial blood pH and bicarbonate concentration were lower (p < 0.01) and the anion gap was larger (p < 0.01) in CS dogs than in the HW-free dogs. Serum lactic acid level in nonsurviving dogs (13.2 +/- 3.9 mmol/l) was higher (p < 0.01) than in the HW-free (1.7 +/- 0.8 mmol/l) and surviving dogs (2.7 +/- 1.8 mmol/l). The PaO2 correlated significantly with mean pulmonary arterial pressure (r = -0.65, p < 0.01), cardiac index (r = 0.44, p < 0.05) and total pulmonary resistance (r = -0.70, p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)