Regional blood flows are affected differently by PEEP when the abdomen is open or closed: An experimental rabbit model

Abstract

Objective: The study of induced circulatory changes requires simultaneous assessment of multiple regional circulations because of interactions and compensatory mechanisms. Positive end expiratory pressure mechanical ventilation (PEEP) is known to cause marked, and potentially deleterious, cardiovascular changes. Our aim was to use a comprehensive approach to assess PEEP-induced circulatory changes in open vs closed abdomen animals. Material and methods:In the anesthetized rabbit, we used implantable Doppler micro-probes to measure blood flow simultaneously in the ascending aorta, inferior vena cava, portal vein, hepatic artery, common carotid artery, and renal artery. We studied spontaneously breathing animals (Group A), and open (Group B) and closed abdomen (Group C) animals mechanically ventilated at 0 (ZEEP) and 12 cm H 2 O PEEP.Results: In Group A, all biological and hemodynamic variables remained unchanged for three hours at the end of the surgical procedure. In Groups B and C, ZEEP produced no significant hemodynamic change. PEEP induced a decrease in carotid, hepatic, and renal artery blood flow in Groups B and C, a decrease in heart rate and mean arterial blood pressure in Group B, and a decrease in aorta blood flow in Group C.

Acute Renal Failure and Mechanical Ventilation: Reality or Myth?

“…9 RBF is primarily affected by PEEP because of sympathetic activation related to increased plasma renin activity. 29 Results of other studies 9,35 have also suggested that although total RBF is relatively unchanged, blood flow is redistributed from the cortical to the juxta medullary nephrons. This redistribution would be associated with decreased urine output, decreased creatinine clearance, and an increased fractional resorption of sodium 35 ( Figure 4).…”

“…22 Positive end-expiratory pressure (PEEP) may reduce cardiac output by causing a further increase in intrathoracic pressures, which compresses the pulmonary vasculature. 29 This change increases right ventricular afterload, leading to a decrease in emptying and ultimately a decrease in left ventricular preload. [29][30][31][32] Left ventricular distensibility also decreases, with an associated decrease in left ventricular function, especially with PEEP greater than 15 cm H 2 O.…”

“…29 This change increases right ventricular afterload, leading to a decrease in emptying and ultimately a decrease in left ventricular preload. [29][30][31][32] Left ventricular distensibility also decreases, with an associated decrease in left ventricular function, especially with PEEP greater than 15 cm H 2 O. The decrease in left ventricular function causes a decrease in venous return to the right side of the heart and an increase in pulmonary artery pressures.…”

Thoracic, peripheral, and cerebral volume, circulatory and pressure responses to PEEP during simulated hemorrhage in a pig model: a case study

“…In turn, the reduced output from the right ventricle leads to a reduced stroke volume in the left ventricular and a reduction in cardiac output [ 10 ]. Decreased cardiac output affects the cerebral circulatory system by increasing intracranial pressure and reducing cerebral perfusion pressure and thereby reducing cerebral blood flow [ 11 ].…”