Selective positive end-expiratory pressure and cardiac function in dogs

Effects of general (G) versus selective (S) right (R) and left (L) positive end-expiratory pressure (PEEP) were compared during differential lung ventilation in 11 anaesthetized dogs in the supine position. GPEEP 20 cm H₂O decreased cardiac output (1 min^–1) from 2.9±0.2 (mean±SE) to 1.7±0.5 (p<0.05), RPEEP from 2.8±0.2 to 2.2±0.2 (p<0.05) while LPEEP caused no significant change in cardiac output. GPEEP increased pleural pressure more than SPEEP. Pleural pressure was asymmetric during SPEEP. Both SPEEP and GPEEP increased pericardial pressure uniformly, but the increase was less marked with SPEEP. During GPEEP 20 cm H₂O transmural left ventricular end-diastolic pressure (LVEDP) decreased markedly. SPEEP caused less marked reductions in transmural LVEDP. Qualitatively similar, but less marked changes were observed with PEEP 10 cm H₂O. In conclusion, cardiac output decreased less with selective PEEP than with general PEEP. This was explained by less increase in pleural and pericardial pressure, and accordingly less decrease in LV transmural filling pressure.