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Abstract

Introduction: Approximately 40% of patients admitted to critical care units require mechanical ventilation (MV). Volume status and cardiac function have been considered important predictors of weaning among patients in the ICU but have not been studied among patients on prolonged MV. This study was conducted to study the role of volume status and cardiac function (as assessed via echocardiography) as predictors in this population. Hypothesis: Volume status and cardiac function assessed via echocardiogram predict weaning outcomes among patients on prolonged MV. Methods: We conducted a retrospective chart review of all adult patients on prolonged MV admitted to the Respiratory Special Care Unit (ReSCU, a long term weaning unit) at the Cleveland Clinic Hospital from April 2011 through May 2012. Prolonged MV was defined as need for MV for at least 6 hours daily for at least 21 consecutive days. Liberation from MV within 24 hours of admission to the unit and unavailability of echocardiogram in 2 weeks prior to admission or at admission were grounds for exclusion (n=66, mean age 60.8 years, M:F 33:33).Demographic, clinical and laboratory variables on day of admission were recorded. Echocardiogram done at the time of admission to the unit or within the last 2 weeks was reviewed and variables reflective of volume status (such as left atrium size, IVC collapsibility) and right and left ventricular function were recorded. Successful weaning, defined as breathing independent of MV for? 72 consecutive hours, was the primary endpoint. Variables were compared between patients who were weaned versus those who could not be weaned. Results: Caucasians formed the majority of the study group (n=53, 80.3%) followed by African Americans (n=10, 15.2%) Pneumonia was the most common etiology for respiratory failure. 37 patients (56.1%) patients were successfully weaned. Weaned patients were younger (mean age 55 ± 18 vs 68 ± 12 years, p=0.001) and had better nutritional status (mean albumin levels 2.73 ± 0.44 vs 2.42 ± 0.41 g/dL, p=0.005). None of the echocardiographic parameters predicted successful weaning (weaned vs not weaned respectively: left ventricular ejection fraction 56.1 ± 7.6% vs 52.4 ± 10.5%; left atrial enlargement among 40% vs 50%; mean right ventricular systolic pressure 42.3 ± 19.9 vs 41.8 ± 15.2 mm Hg; presence of right ventricular systolic dysfunction among 51.4% vs 41.7%; right ventricular dilatation 45.7% vs 36%; right atrial enlargement 19.4% vs 22.2%; mean inferior vena cava diameter 2.1 ± 0.5 cm vs 2.1 ± 0.4 cm; all P=NS). Conclusions: Most patients requiring prolonged MV can be successfully weaned. Whereas younger age and better nutritional status at baseline favors successful wean, volume status and cardiac function assessed via echocardiogram do not help to prognosticate these patients.