Assessment of factors that influence weaning from long-term mechanical ventilation after cardiac surgery

Abstract

OBJECTIVE: To analyze parameters of respiratory system mechanics and oxygenation and cardiovascular alterations involved in weaning tracheostomized patients from long-term mechanical ventilation after cardiac surgery. METHODS: We studied 45 patients in their postoperative period of cardiac surgery, who required long-term mechanical ventilation for more than 10 days and had to undergo tracheostomy due to unsuccessful weaning from mechanical ventilation. The parameters of respiratory system mechanics, oxigenation and the following factors were analyzed: type of surgical procedure, presence of cardiac dysfunction, time of extracorporeal circulation, and presence of neurologic lesions. RESULTS: Of the 45 patients studied, successful weaning from mechanical ventilation was achieved in 22 patients, while the procedure was unsuccessful in 23 patients. No statistically significant difference was observed between the groups in regard to static pulmonary compliance (p=0.23), airway resistance (p=0.21), and the dead space/tidal volume ratio (p=0.54). No difference was also observed in regard to the variables PaO2/FiO2 ratio (p=0.86), rapid and superficial respiration index (p=0.48), and carbon dioxide arterial pressure (p=0.86). Cardiac dysfunction and time of extracorporeal circulation showed a significant difference. CONCLUSION: Data on respiratory system mechanics and oxygenation were not parameters for assessing the success or failure. Cardiac dysfunction and time of cardiopulmonary bypass, however, significantly interfered with the success in weaning patients from mechanical ventilation

Effects of Positive End-Expiratory Pressure on Mechanical Ventilation Duration after Coronary Artery Bypass Grafting: A Randomized Clinical Trial

“…We found similar data in our research, with mean mechanical ventilation duration of approximately six hours in uncomplicated patients. The presence of cardiac dysfunction and prolonged cardiopulmonary bypass were factors associated with an increased duration of mechanical ventilation in a study by Nozawa, et al 17) Other studies evaluating the effect of PEEP on postoperative cardiac surgery reported controversial results regarding the duration of mechanical ventilation. Michalopoulos, et al 18) compared the effects of different levels of PEEP (0, 5 and 10 cmH 2 O) on arterial oxygenation in patients undergoing cardiac surgery and showed no difference in the duration of mechanical ventilation between groups.…”

Factors Associated With Failure of Weaning From Long-term Mechanical Ventilation After Cardiac Surgery

“…However, this ratio was not useful in predicting the success or failure of weaning from long-term mechanical ventilation in our study, because both groups had similar values. Nozawa, et al 10) reported similar results in another study involving patients who underwent longterm mechanical ventilation after cardiac surgery.…”

“…6) Parameters of respiratory mechanics and oxygenation are commonly used to wean patients with chronic obstructive pulmonary disease (COPD) and other pulmonary disorders from long-term mechanical ventilation. [7][8][9] Yet, as we have previously shown, 10) arterial blood gas analysis and the determination of vital capacity and minute volume often fail to predict extubation success in patients after cardiac surgery. Others have identified advanced age, female sex, (extended) time of extracorporeal circulation, cardiac dysfunction, and low cardiac output as factors associated with the failed weaning of cardiac patients from long-term ventilation 2,4,5) and postoperative cardiac dysfunction and neurological alterations, as factors contributing to their high mortality.…”

Análise do tempo de ventilação mecânica e internamento em pacientes submetidos a cirurgia cardíaca

“…14 afirmam que em pacientes submetidos à cirurgia cardíaca, que requerem VMI prolongada, os dados de mecânica respiratória e oxigenação não foram fatores envolvidos no sucesso ou insucesso no desmame. Porém, disfunção cardíaca e tempo de CEC influenciaram diretamente no sucesso do desmame.…”