RESUMEN
This study was conducted to evaluate the hemodynamic and blood gas variations in response to PEEP at different levels during mechanical ventilation in 30 adult patients having normal cardio-respiratory functions. Thiopentone, suxamethonium, halothane, nitrous oxide in oxygen and atracurium were used for induction and maintenance of anesthesia. Ventilation was controlled with ZEEP for 30 minutes followed by PEEP for another 30 minutes. Level of PEEP varied according to the group [5, 10 or 15 cm H20]. Hemodynamic changes in the form of decreased systolic and mean blood pressure and increased CVP were prominent with higher levels of PEEP. These levels were accompanied with decreased PaO2, increased PaCO2 and decreased pH. PEEP of 10 cm H20 was found to be a suitable level with minimal hemodynamic, ventilatory and metabolic changes, above which undesirable effects mostly develop. So, PEEP of 10 cm H20 is recommended in patients submitted to prolonged surgical procedures