Effects on Hemodynamics and Renal Function of PEEP

ABSTRACT

BACKGROUND AND OBJECTIVE: Controlled mechanical ventilation(CMV) with positive end expiratory pressure(PEEP) is frequently employed in the treatment of critically ill patients in the surgical intensive care unit. CMV with PEEP can impair many hemodynamic parameters such as a decrease in cardiac index. These hemodynamic changes may lead to vital organ dysfunctions such as oliguria. The purpose of this current study is to examine the effect on the hemodynamic and renal function of positive end expiratory pressure. MATERIALS AND METHODS: The study is performed in 10 patients treated with PEEP. Starting with no PEEP and then adding 4cmH2O of PEEP in 2 hrs interval till 12cmH2O of PEEP is reached. At each procedure, the hemodynamic parameters, urine output, creatinine clearance, fractional excretion of sodium are measured. RESULTS: The mean arterial pressure was decreased from 102.2+/-5mmHg(mean+/-SEM) at 0cmH2O of PEEP to 91.6+/-5.4mmHg at 12cmH2O of PEEP(P<0.05). The cardiac index decreased from 4.21+/-0.21L/min/m2 at 0cmH2O of PEEP to 3.59+/-0.14L/min/m2 at 8cmH2O of PEEP(P<0.01) and 3.25+/-0.12L/min/m2 at 12cmH2O of PEEP(P<0.01). Urine output decreased from 1.61+/-0.21ml/hr/kg at 0cmH2O of PEEP to 1.21+/-0.19ml/hr/kg at 8cmH2O of PEEP(P<0.05), 0.85+/-0.13ml/hr/kg at 12cmH2O of PEEP(P<0.01). Creatinine clearance decreased from 114.9+/-3.36ml/min at 0cmH2O of PEEP to 97+/-5.28ml/min at 8cmH2O of PEEP(P<0.01) and 80.2+/-3.11ml/min at 12cmH2O of PEEP(P<0.01). The pulmonary capillary wedge pressure, fractional excretion of sodium were unchanged. CONCLUSION: CMV with 8cmH2O of PEEP significantly affected the hemodynamic and renal function. At 12 cmH2O of PEEP, the changes in urine output and renal function may be affected more by hemodynamic changes than hormonal changes.