Background: Acute kidney injury (AKI) is defined as oliguria or rise in serum creatinine but oliguria alone as a diagnostic criterion may over-diagnose AKI. Objectives: Given the association between fluid overload and AKI, we aimed to determine if positive fluid balance can complement the known parameters in assessing outcomes of AKI. Design: Prospective observational study. Setting: Teaching hospital in Vancouver, Canada. Patients: 111 consecutive patients undergoing elective cardiac surgery from January to April 2012. Measurements: Outcomes of cardiac surgery intensive care unit (CSICU) and hospital length of stay (LOS) in relation to fluid balance, urine output and serum creatinine. Methods: All fluid input and output was recorded for 72 hours post-operatively. Positive fluid balance was defined as >6.5 cc/kg. Daily serum creatinine and hourly urine output were recorded and patients were defined as having AKI according to the AKIN criteria. Results: Of the patients who were oliguric, those with fluid overload trended towards longer LOS than those without fluid overload [CSICU LOS: 62 and 39 hours (unadjusted p-value 0.02, adjusted p-value 0.58); hospital LOS: 13 and 9 days (unadjusted p-value: 0.05, adjusted p-value: 0.16)]. Patients with oliguria who were fluid overloaded had similar LOS to patients with overt AKI (change in serum creatinine ≥ 26.5 μmol/L), [CSICU LOS: 62 and 69 hours (adjusted p value: 0.32) and hospital LOS: 13 and 14 days (adjusted p value: 0.19)]. Patients with oliguria regardless of fluid balance had longer CSICU LOS (adjusted p value: 0.001) and patients who were fluid overloaded in the absence of AKI had longer hospital LOS (adjusted p value: 0.02). Limitations: Single centre, small sample, LOS as outcome. Conclusions: Oliguria and positive fluid balance is associated with a trend towards longer LOS as compared to oliguria alone. Fluid balance may therefore be a useful marker of AKI, in addition to urine output and serum creatinine.

Right ventricular failure after orthotopic heart transplantation is associated with significant mortality and morbidity. We report the use of a paracardiac microaxial pump, the Impella RD, as a bridge to recovery in a patient with right ventricular infarction after orthotopic heart transplantation.

498 The purpose was to determine which chronic obstructive pulmonary disease(COPD) patients benefitted most from comprehensive, phase II pulmonary rehabilitation by retrospectively comparing clinical characteristics and physiological variables to improvement in 6- and 12-minute walk test distance(WTD). Information was collected on 129 patients who entered phase II pulmonary rehabilitation between 1992 and 1996. There were no statistically significant relationships between change in WTD and age, sex, marital status, smoking history, lung function, and oxygen requirements. There was a slight relationship with weight (r=-0.30; r2=0.09; p<.005). Obese patients(BMI between 30.1 and 40.0) had less improvement in WTD (mean change=31.0 m), and underweight patients (BMI≤20) had the greatest improvement in WTD(average change=71.8 m). Additionally, morbidly obese patients (BMI>40.1) had a 50% dropout rate in the program compared with normal weight patients(BMI between 20.1 and 25.0) with a 33% dropout rate and underweight patients with a 44% dropout rate. Weight did not change significantly during the program (mean weight pre=76.1 kg; mean weight post=76.0 kg). These findings indicate that physicians may want to consider potential for compliance and improvement when prescribing phase II pulmonary rehabilitation for the morbidly obese patient.