Abstract

BACKGOUND: It has been suggested that the addition of positive end-expiratory pressure (PEEP) to the patients with ventilator support leads to an impairment on renal hemodynamics and water- and sodium-retaining hormonal systems, such as plasma renin activity (PRA), plasma aldosterone, urinary antidiuretic hormone (ADH).
METHODS
To evaluate the effects of 5 cmH2O and 10 cmH2O PEEP on renal function, we measured the plasma concentration of sodium (Na+), potassium (K+) and creatinine, urinary excretion of Na+, K+ and urine output in eight normovolemic male patients requiring ventilator support. Also changes in mean arterial pressure, pulse rate, arterial oxygen tension (PaO2) and carbon dioxide tension (PaCO2) during the experimental period were measured in these patients.
RESULTS
Both 5 and 10 cmH2O PEEP showed no significant effect on the mean arterial pressure, heart rate, PaO2, and PaCO2. Both 5 and 10 cmH2O PEEP showed no significant effect on the plasma concentration of sodium, potassium and creatinine. 5 cmH2O PEEP showed no significant effect on the urinary excretion of sodium, potassium and urine output, but 10 cmH2O PEEP showed significant effect on the urinary excretion of sodium (19% decrease, p<0.05), and urine output (12.5% decrease, p<0.05) respectively.
CONCLUSIONS
10 cmH2O PEEP was revealed to decrease urinary sodium excretion along with urinary output and this phenomenon was likely to relate with water- and sodium-retaining hormonal systems. These results suggested that it was preferable to apply high PEEP cautiously in patients with impaired renal function.

• Keywords: Positive end-expiratory pressure;Renal function;Urine output;Ventilation;mechanical;