title: Influence of changes in cardiac output on the acid-base status of arterial and mixed venous blood.
abstract: While maintaining the arterial CO2 tension constant near the normal level of the dog (4.3 kPa), we studied the influence of decreasing cardiac output on both the arterial and mixed-venous blood acid-base status in anaesthetized, artificially ventilated dogs. Cardiac output was manipulated by applying positive end-expiratory pressure (PEEP), and by beta-adrenergic blockade to suppress a compensatory heart rate response. The systemic vascular response was attenuated by alpha-adrenergic blockade. Metabolic rate remained virtually unchanged when cardiac output decreased. Under these conditions a fall in cardiac output led to a shift of the arterial acid-base status in the direction of a metabolic acidosis. The changes occurring in the mixed-venous blood resembled those of an in-vivo CO2 bufferline, with the shift being such as if a respiratory acidosis was developing.
mesh_terms: D000137:Acid-Base Imbalance / Q000209:etiology*; D000138:Acidosis / Q000209:etiology; D000142:Acidosis, Respiratory / Q000209:etiology; D000818:Animals; D001158:Arteries; D001769:Blood; D002245:Carbon Dioxide / Q000097:blood; D002302:Cardiac Output / Q000187:drug effects; D004285:Dogs; D005260:Female; D006863:Hydrogen-Ion Concentration; D008297:Male; D010643:Phenoxybenzamine / Q000494:pharmacology; D011175:Positive-Pressure Respiration; D011433:Propranolol / Q000494:pharmacology; D014680:Veins
chemical_list: D010643:Phenoxybenzamine; D002245:Carbon Dioxide; D011433:Propranolol