Literature is limited on weaning and survival outcomes in patients on prolonged mechanical ventilation (PMV), which is defined as ventilatory support >21 days . The objective of this study was to determine factors affecting weaning and survival outcomes in patients on PMV.
We retrospectively studied patients on PMV admitted for weaning to a regional weaning center over a 3-year period. The following data was abstracted from records: patients’ age, sex, precipitating cause of respiratory failure, duration of ventilatory support (Dvs), percent ideal bodyweight (%IBW), body mass index (BMI), serum albumin, prealbumen, BUN, serum creatinine (Cr), creatinine clearance (CrCl), hemoglobin (Hb), WBC count, total lymphocyte count (TLC) and serum TSH levels. Outcomes noted were liberation from PMV, defined as being off ventilatory support for > 7 days and survival (alive at discharge or not). Multivariate analysis was used to determine relation between studied parameters and outcome. Chi square test was used to test statistical significance, with p < 0.05 being deemed statistically significant.
Of 202 patients studied, 48% were males. Mean age was 66.3±16 years. Cause of respiratory failure was cardiovascular surgery in 27%; other surgery in 14.5%; COPD in 21%; pneumonia in 9%; ARDS in 6%; neurological disease in 18.5% and CHF in 4%. Mean Dvs was 60.8 days (range 21-680 days). Sixty-seven percent were liberated from PMV; 33% failed to wean. Seventy-one percent survived to discharge. Dvs < 12 weeks was associated with better weaning outcome. Table 1 depicts studied parameters in liberated patients and patients that failed to wean. On multivariate analysis, factors associated with adverse impact on liberation were: COPD as cause of respiratory failure, longer Dvs, lower CrCl. Factors associated with adverse survival outcome were CHF and COPD as causes of respiratory failure, higher Cr and lower TLC.
Multiple factors affect weaning and survival outcomes in patients on PMV.
More studies are needed to develop screening criteria for selection of appropriate patients on PMV for admission to weaning facilities.
Studied Parameters in Patients Liberated and Failed-To-WeanParametersLiberatedFailedAge (years)66±768±15Dvs (days)51±3261±66BMI (kg/sqm)27±826±8% IBW121±36119±36Protein (gm/dL)5.9+0.85.5±0.8Albumen (gm/dL)2.6+0.52.5±0.5Prealbumen (mg/dL)20±720±8BUN (mg/dL)29±2132±17Cr (mg/dL)0.8±0.90.8±0.8CrCl (ml/min)69±3461±32Hb (gm/dL)10±1.410±1.3WBC10±510±3TLC (cells/cumm)1672±10601597±995TSH (mU/L)4.2±93.9±11
Debapriya Datta, None.