Effects of sitting position on the strength of respiratory muscles during weaning of patients under prolonged mechanical ventilation in the postoperative period of cardiovascular surgery

Abstract

The purpose was to study the effects of sitting position, in ventilatory and hemodynamic parameters, in patients under prolonged mechanical ventilation, in the postoperative of cardiovascular surgery. Participated 40 postoperative cardiovascular patients, intubated and mechanically ventilated, were randomized into control group (n=17) and intervention group (n=23). Hemodynamic parameters, arterial blood gases, respiratory muscle strength and ventilometry, were measured in two moments: first and second evaluation, with 30-minute interval between measurements. In the control group, both evaluations were performed at head of the bed elevated at 30°. In the sitting group, the first evaluation was developed at 30° and the second, (30 minutes after transfer to the armchair) in the sitting position (90°). The mean age of patients was 64.7±11.2 years. There were no differences regarding the hemodynamic parameters, blood gas analysis, forced vital capacity, minute ventilation and tidal volume. However, a significant increase in maximal inspiratory pressure (MIP) in the intervention group was observed (p<0.01). We conclude that stable patients in the postoperative period of cardiovascular surgery, mechanically ventilated, maybe benefits of the sitting position observed of increased inspiratory muscle strength. Furthermore, no significant hemodynamic changes, and it was well tolerated when the patients were transferred to the sitting position, so it was considered a safe procedure.