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

Abstract

SUMMARYThe purpose of this prospective, quantitative, comparative study, conducted at the 55 bed cardiothoracic intensive care unit of the Heart Institute (InCor), University of Sao Paulo Medical School, was to identify factors involved in the weaning of patients who require long-term (> 10 days) mechanical ventilation after cardiac surgery.The subjects included all patients who underwent open-heart surgery with cardiopulmonary bypass during a 10 month period from April 2000 to January 2001 (n = 946). From this group, 52 (5.7%) patients who required a tracheotomy for the management of long-term mechanical ventilation after cardiac surgery with cardiopulmonary bypass were selected. Pre-, intra-and postoperative data from patients who were not successfully weaned after reintubation and who underwent an elective tracheotomy were compared.Parameters of respiratory mechanics such as respiratory complications, oxygenation, and cardiac, renal, and neurological function were evaluated. Weaning success was defined as the ability of a patient to tolerate 48 hours without pressure or flow support from a mechanical ventilator. A patient was considered to have failed weaning if they died or remained under ventilation for more than 8 weeks. Of the 52 patients studied, 25 were successfully weaned, 21 died, and 6 remained ventilated for more than 8 weeks. We found significant statistical differences (P <0.05) between the groups with respect to success or failure in LVEF (P = 0.0035), the need for vasoactive agents (P = 0.0018), and renal failure (P = 0.002). Parameters of respiratory mechanics and oxygenation (eg, static airway compliance, airway resistance) did not influence the success or failure of weaning. There was a significant difference in relation to the presence of pneumonia (P = 0.0086) between the two groups. Although neurological complications were more frequent in patients in the weaning success group, the failure group had lower GCS scores, which is indicative of worse prognoses.It is concluded that cardiac dysfunction, the need for dialysis, and pneumonia are determinants for weaning failure in patients undergoing long-term mechanical ventilation after cardiac surgery. (Int Heart J 2005; 46: 819-831)

Korelasi antara Lama Pintas Jantung Paru dan Lama Bantuan Ventilasi Mekanis pada Pasien Pascabedah Pintas Arteri Koroner di Unit Perawatan Intensif Jantung Rumah Sakit Dr. Hasan Sadikin Bandung

“…Penelitian awal mempertimbangkan bahwa pasien yang menggunakan ventilasi mekanik pascabedah jantung akan mengalami stabilisasi sistem kardiovaskular dan sistem organ lainnya dari pengaruh respons inflamasi sebelumnya yang disebabkan oleh mesin pintas jantung paru. 1,2 Fungsi paru dan oksigenasi mengalami penurunan sebanyak 20-90% pada pasien pascabedah pintas arteri koroner dengan menggunakan mesin pintas jantung paru. Penggunaan bantuan ventilasi mekanis jangka panjang pascabedah pintas arteri koroner merupakan salah satu komplikasi pascaoperasi yang dapat meningkatkan morbiditas dan mortalitas, sebanding dengan peningkatan biaya rawat dan menurunkan kualitas hidup.…”

Weaning From Mechanical Ventilation in Patients With Congestive Heart Failure

“…The weaning screen is performed more frequently if a faster recovery from CHF appears to be likely and if a weaning attempt seems appropriate in the short-term. 4,8,24,25 Additional weaning criteria include fraction of inspired oxygen (FiO 2 ) Ͻ0.5, PEEP less than 5 to 8 cm H 2 O, ability to trigger a spontaneous breath without desaturation, absence of significant need of pressors, and stable hemodynamics indicating absence of uncontrolled arrhythmias or valvular heart disease. Optimization of CHF in this context implies the ability to decrease PEEP and FiO 2 to the wean screen limits.…”

“…During an SBT, the patient is given a T-Tube trial, continuous positive airway pressure of 5 cm H 2 O or a PS ventilation trial of 5 to 7 cm H 2 O for 30 to 120 minutes, 8,26 although subtle variations in these methods have been used in other reports. 3,4,12,15,25,27 The longer duration of the SBT is for subjects who have been dependent on mechanical ventilation 24 for longer durations and/or who have failed weaning or extubation before.…”

“…The presence of CHF has been associated with a failure to wean from mechanical ventilation. 3,4 The pathologic changes affecting gas exchange and oxygen transport during CHF are detailed in the subsequent sections. The effect of mechanical ventilation on gas exchange and oxygen transport in patients with CHF is further described.…”

Estudo dos indicadores durante o desmame da ventilação mecânica em pacientes submetidos à cirurgia cardíaca

“…Underlying left ventricular dysfunction is an important cause of weaning failure in critically ill patients, particularly during the postoperative period after cardiac surgery, and can be the result of perioperative myocardial ischemia, prolonged CPB, or inadequate myocardial protection (27)(28)(29)(30). This condition may be difficult to recognize within the first 24 h after cardiac surgery.…”