Hemodynamic and regional blood flow responses of neonatal and adult dogs to endotoxin challenge.

Our recent studies showed developmental differences in the functional responses of the myocardium to isoproterenol and exogenous calcium, suggesting that decreased cardiovascular reserves in the immature heart contribute to the greater morbidity/mortality reported in neonatal compared to adult endotoxin shock. In this study, hemodynamic, hormonal and regional blood flow responses to Escherichia coli endotoxin challenge (1 mg/kg, 055:35 B lipopolysaccharide) were compared in adult (N = 12) and neonatal (19-21 days of age, N = 38) dogs. Compared to neonates, adult dogs had higher baseline mean arterial pressures (78 +/- 3 vs. 127 +/- 7 mmHg, P = 0.01), while values were lower for cardiac output (635 +/- 30 vs. 130 +/- 7 ml/kg, P = 0.01), left ventricular +dP/dt max (4,500 +/- 200 vs. 2,700 +/- 190 mmHg/sec, P = 0.02), heart rate (138 +/- 3 vs. 86 +/- 6 beats/min, P = 0.02), coronary flow (3.46 +/- 0.18 vs. 1.19 +/- 0.15 ml/min/g, P = 0.01), serum glucose (136 +/- 6 vs. 113 +/- 4 mg%, P = 0.01), insulin (20 +/- 3 vs. 15 +/- 2 mU/ml, P = 0.05), and glucagon (518 +/- 98 vs. 172 +/- 27 pg/ml, P = 0.01). Endotoxin caused progressive cardiocirculatory dysfunction and metabolic acidosis, regardless of age.(ABSTRACT TRUNCATED AT 250 WORDS)