Application of noninvasive ventilation in acute respiratory failure after cardiovascular surgery.
To examine ventilatory response, oxygenation-related, and hemodynamics of patients with hypoxemic acute respiratory failure (ARF) submitted to noninvasive mechanical ventilation (NIV) during the postoperative phase of cardiovascular surgery in order to identify predictive variables of success, and to compare the different types of NIV.



Seventy patients with hypoxemic ARF were randomized to one of three modalities of NIV--continuous positive airway pressure (CPAP) and ventilation with two pressure levels (PEEP + SP and BiPAP). Ventilation, oxygenation-related, and hemodynamics variables were analyzed at pre-application, and 3, 6, and 12 hours after the protocol began.



Thirteen patients were excluded. Thirty-one patients progressed to independence from ventilatory support and comprised the success group, and 26 required orotracheal intubation and were considered the nonsuccess group. Age, initial heart rate (HR), and respiratory rate (RR) showed elevated levels in the nonsuccess group (p=0.042, 0.029, and 0.002, respectively). A greater number of intraoperative complications were seen in the nonsuccess group (p=0.025). Oxygenation variables increased only in the success group. Among the NIV types, 57.9% of patients in the ventilator group, 57.9% in the two-pressure levels group, and 47.3% in the CPAP group progressed with success. Oxygenation and RR variables showed improvement only in the groups with two pressure levels.



Patients with hypoxemic ARF in the postoperative stage after cardiovascular surgery showed better oxygenation, RR, and HR during NIV application. In older patients and those with higher baseline RR and HR values, NIV was not sufficient to reverse ARF. The two-pressure level modes showed better results.
Coimbra
Vera Regina de Morais
VR
Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brasil.
Lara
Rodrigo de Almeida
Rde A
Flores
Eriko Gonçalves
EG
Nozawa
Emília
E
Auler
José Octávio Costa
JO
Feltrim
Maria Ignez Zanetti
MI
D000368:Aged; D000704:Analysis of Variance; D002318:Cardiovascular Diseases / Q000601:surgery*; D016009:Chi-Square Distribution; D045422:Continuous Positive Airway Pressure / Q000379:methods; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D000860:Hypoxia / Q000628:therapy*; D007431:Intraoperative Complications; D007442:Intubation, Intratracheal; D008875:Middle Aged; D011182:Postoperative Care / Q000379:methods; D011183:Postoperative Complications / Q000517:prevention & control; D012119:Respiration; D012121:Respiration, Artificial / Q000379:methods*; D012131:Respiratory Insufficiency / Q000628:therapy*; D018709:Statistics, Nonparametric; D017211:Treatment Failure