Effects of Noninvasive Positive-Pressure Ventilation with Different Interfaces in Patients with Hypoxemia after Surgery for Stanford Type A Aortic Dissection

BACKGROUND Hypoxemia is a severe perioperative complication that can substantially increase intensive care unit and hospital stay and mortality. The aim of this study was to determine the effects of non-invasive positive-pressure ventilation (NIPPV) in patients with hypoxemia after surgery for Stanford type A aortic dissection, and to compare the effects of helmet and mask NIPPV. MATERIAL AND METHODS We recruited 40 patients who developed hypoxemia within 24 h after extubation after surgery for Stanford type A aortic dissection in the Beijing Anzhen Hospital. The patients were randomly divided into the helmet and mask NIPPV groups. The primary endpoints were blood oxygenation levels at 1 and 6 h after initiation and at the end of the treatment. The secondary endpoint was patient outcome, including mortality; incidence of pulmonary atelectasis, pneumonia, re-intubation, and sepsis; and length of ICU and hospital stays. RESULTS NIPPV improved oxygenation in both groups. Compared with pretreatment levels, the oxygenation index (PaO2/FiO2), PaO2, PaCO2, and respiratory rate (RR) improved in the initial (0-1 h), maintenance (1-6 h), and end stages of the treatment (P<0.05). Compared with mask ventilation, helmet ventilation better improved pH, PaO2, SpO2, PaO2/FiO2, and decreased PaCO2 in the 3 stages (P<0.05). The incidence of major complications, including flatulence, intolerance, and facial pressure sores, was significantly lower with helmet ventilation. CONCLUSIONS NIPPV effectively improved oxygenation and reduced PaCO2 in patients who developed hypoxemia soon after extubation following surgery for Stanford type A aortic dissection. Compared with mask NIPPV, helmet NIPPV more rapidly increased PaO2 and reduced PaCO2, increased patient tolerance and comfort, and reduced complications.