The effect of hypocarbia on the cardiovascular system of puppies.
Respiratory alkalosis (hypocapnia) is used to treat persistent pulmonary hypertension in newborns. With the exception of the brain, there are no data on the effects of hypocapnia on organ blood flow in the neonate. Therefore, we examined the effects of 2 h of hypocapnia on blood pressure, oxygen consumption, cardiac output and organ blood flows in puppies. In six animals (group I), reducing the PaCO2 to 21.8 +/- 1.5 mm Hg (pH 7.62 +/- 0.04) caused an immediate and sustained reduction in cerebral blood flow (40%) and in myocardial blood flow (25%). There were no significant changes in arterial blood pressure, total body oxygen consumption, cardiac output, right and left ventricular rate-pressure product, or blood flow to the gut, liver, muscle, and kidneys. In four control animals (group II)(PaCO2 39.8 +/- 3.0, pH 7.38 +/- 0.04), there were no changes in any of the measured variables (arterial blood pressure, total body oxygen consumption, cardiac output, or blood flow to any organ, including brain and heart) during 2 h of normocarbic ventilation. We did not determine whether the reductions in cerebral and myocardial blood flows were detrimental. We suspect that they were not because the animals did not develop metabolic acidosis and they had normal cardiac outputs, and ventricular rate-pressure products throughout the study.
D000136:Acid-Base Equilibrium / Q000187:drug effects; D000472:Alkalosis, Respiratory / Q000503:physiopathology; D000818:Animals; D000831:Animals, Newborn; D001794:Blood Pressure / Q000187:drug effects; D002245:Carbon Dioxide / Q000097:blood* / Q000494:pharmacology; D002302:Cardiac Output / Q000187:drug effects; D002319:Cardiovascular System / Q000503:physiopathology*; D004285:Dogs; D006439:Hemodynamics / Q000187:drug effects; D010100:Oxygen / Q000097:blood; D012039:Regional Blood Flow / Q000187:drug effects; D014655:Vascular Resistance / Q000187:drug effects
D002245:Carbon Dioxide; D010100:Oxygen