Systemic oxygen delivery and consumption in dogs with heartworm disease

To investigate systemic oxygen (O2) transport, we calculated the oxygen delivery index (Do2I), oxygen consumption index (Vo2I) and oxygen extraction ratio (ER) in dogs with heartworm (HW) disease. The Do2I was 770 +/- 331 ml/min/kg in dogs mildly affected with pulmonary HW disease showing respiratory signs, mild anemia and mild cardiac insufficiency (n = 34); 238 +/- 155 ml/min/kg in dogs with ascitic pulmonary HW disease (n = 7); and 577 +/- 320 ml/min/kg in dogs with caval syndrome (CS) which survived (n = 15) or died (n = 7) after surgical HW removal. The Do2I was lower (P < 0.01) in all HW-infected groups, especially in ascites and CS-non-surviving dogs, than in HW-free dogs (n = 11, 1041 +/- 264 ml/min/kg). The Vo2I was higher in some mildly affected dogs (161 +/- 88 ml/min/kg), and lower (P < 0.01) in ascitic dogs (45 +/- 53 ml/min/kg) than in HW-free dogs (123 +/- 44 ml/min/kg). The ER was higher (P < 0.01) in all HW-infected groups than in HW-free dogs. The Do2I correlated significantly with Vo2I (r = 0.84, P < 0.01), and the Vo2I correlated significantly with ER (r = 0.48, P < 0.01). The Do2I correlated significantly with arterial O2 tension (r = 0.33), serum LDH (r = -0.46) and CK (r = -0.46) activities, serum urea nitrogen (UN, r = -0.32) and lactic acid (LA, r = -0.39) concentrations and cardiac index (r = 0.64).(ABSTRACT TRUNCATED AT 250 WORDS)