BACKGROUND: Cardiac surgery is widely used in the
treatment of
cardiovascular diseases . However, several
complications can be observed during the
postoperative period .
Positive end expiratory pressure (PEEP) improves gas exchange, but it might be related to decreased
cardiac output and possible impairment of
tissue oxygenation . The aim of this study was to investigate the
hemodynamic effects and
oxygen saturation of central venous
blood (ScvO2) after increasing PEEP in hypoxemic
patients after
coronary artery bypass (CAB)
surgery .
METHODS: Seventy post-
cardiac surgery patients (CAB), 61 ± 7 years, without
ventricular dysfunction (left
ventricular ejection fraction 57 ± 2%), with
hypoxemia (PaO2/FiO2 ratio <200) were enrolled.
Heart rate ,
mean arterial pressure , arterial and venous
blood samples were measured at
intensive care unit and PEEP was increased to 12 cmH2O for 30min.
RESULTS: As expected, PEEP12 improved arterial
oxygenation and PaO2/FiO2 ratio (p < 0.0001). Reduction in ScvO2 was observed between PEEP5 (63 ± 2%) and PEEP12 (57 ± 1%; p = 0.01) with higher values of
blood lactate in PEEP12 (p < 0.01). No
hemodynamic effects (
heart rate ,
mean arterial pressure ,
SpO2 ; p > 0.05) were related.
CONCLUSION: Increased PEEP after
cardiac surgery decreased ScvO2 and increased
blood lactate , even with higher O2 delivery. PEEP did not interfere in
hemodynamics status in CAB
patients , suggesting that peripheral
parameters must be controlled and measured during
procedures involving increased PEEP in post-
cardiac surgery patients in the
intensive care unit .