Hemodynamics and tissue oxygenation effects after increased in PEEP in coronary artery bypass surgery

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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.

Seventy post-cardiac surgery patients (CAB), 61 ± 7 years, without ventricular dysfunction (left ventricular ejection fraction 57 ± 2%), with hypoxemia (PaO2/FiO2ratio <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 30 min.

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.

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.


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My interest in health and fitness started at a young age. Even though I had been educated and trained as an engineer in Europe I always want to follow my passion. I have made some guest appearances on a health educational program TV in Europe and, this experience, has made me follow my passion of sharing wellness information with others.

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