title: Influence of abdominal pressure and sympathetic vasoconstriction on the cardiovascular response to positive end-expiratory pressure.
abstract: The role of changes in abdominal pressure and sympathetically mediated vasoconstriction in the cardiovascular response to positive end-expiratory pressure was evaluated in 9 mongrel dogs. When the abdomen was widely opened, the decrease in cardiac output caused by positive end-expiratory pressure was the same as that found during control studies. When the abdomen was tightly bound, cardiac output was higher at any positive end-expiratory pressure than in control state (P less than 0.01), but the percent decrease produced by increasing positive end-expiratory pressure was the same. alpha-Adrenergic blockade with phenoxybenzamine produced a significantly greater decrease in cardiac output at any given positive end-expiratory pressure and thus appeared to inhibit the previously operative peripheral vascular adjustments to positive end-expiratory pressure. The major compensatory mechanism in the cardiovascular response to positive end-expiratory pressure thus appears to be mediated via alpha-adrenergic sympathetic factors.
mesh_terms: D000005:Abdomen; D000818:Animals; D001794:Blood Pressure; D002302:Cardiac Output / Q000187:drug effects; D004285:Dogs; D006321:Heart / Q000502:physiology; D006325:Heart Atria; D010643:Phenoxybenzamine / Q000494:pharmacology; D011175:Positive-Pressure Respiration; D011312:Pressure; D011651:Pulmonary Artery; D013909:Thorax / Q000502:physiology*; D014666:Vasomotor System / Q000502:physiology*
chemical_list: D010643:Phenoxybenzamine