Noninvasive Assisted Ventilation in Pulmonary Gas Exchange Dysfunctions in Cardiac Surgical Patients

Abstract

Background. Postextubation pulmonary gas exchange dysfunctions are a potential complication in the activation of cardio-surgical patients in the early periods after surgical intervention. Objective: to evaluate the efficiency of noninvasive assisted ventilation (NIAV) as a method for correcting the pulmonary gas exchange disturbances developing after early activation of cardiosurgical patients. Subjects and methods. The study included 64 patients (36 males and 28 females) aged 21 to 72 (54±2) years who had been operated on under extracorporeal circulation (EC). The duration of EC and myocardial ischemia was 104±6 and 73±4 min, respectively. The indications for NIAV were the clinical manifestations of acute respiratory failure (ARF) and/or PaCO2>50 mm Hg and/or PaO2/FiO2Results. During NIAV, there was improvement (p<0.05) of lung oxygenizing function (the increase in PaO2/FiO2 was 23%), a reduction in Qs/Qt from 21.1±1.9 to 13.9±1.0% (p<0.05). NIAV was accompanied by a decrease in PaCO2 (p<0.05). Hypercapnia regressed in 7 patients with isolated lung ventilatory dysfunction (PaCO2>50 mm Hg) an hour after initiation of NIAV. During and after NIAV, there were reductions in right atrial pressure, mean pulmonary pressure, indexed total pulmonary vascular resistance (ITPVR) (p<0.05). Prior to, during, and following NIAV, mean blood pressure, cardiac index, and indexed total pulmonary vascular resstance did not change greatly. In hypercapnia, the duration of NIAV was significantly less than that in lung oxygenizing function (2.8±0.2 hours versus 4.7±0.5 hours). That of ICU treatment was 23±4 hours. Fifty-two (81%) patients were transferred from ICUs to cardiosurgical units on the following day after surgery. Conclusion. In most cases, NIAV promotes a rapid and effective correction of postextubation lung ventilatory and oxygenizing dysfunctions occurring after early activation of cardiosurgical patients. Key words: non-invasive assisted ventilation, early activation of cardiosurgical patients.