Renal failure requiring hemodialysis has been associated with a poor outcome in patients on prolonged mechanical ventilation (PMV). Serum creatinine (Cr) > 1.3 mg% has been implicated in failure-to-wean from PMV. Literature on the impact of renal failure on weaning is limited. Creatinine clearance (CrCl)provides a better estimate of renal function than serum creatinine. However, no prior studies have examined the relationship of CrCl on weaning outcome in patients on PMV. The objective of this study was to determine the effect of renal function, particularly CrCl, on weaning from PMV.
We retrospectively studied 167 patients on PMV, admitted to a long term acute care facility between 1999-2002, for weaning. These patients had CrCl measured routinely on admission. The following data was obtained: age, sex, cause of respiratory failure and admission BUN, Cr and CrCl. Random urine creatinine (RUCr) and 24-hour urinary creatinine (24-UCr), obtained with CrCl estimation, were also noted. Outcome was liberation from PMV, defined as being off ventilator for > 7 days. Univariate analysis was performed to determine relation between above parameters and outcome. p <0.05 was statistically significant.
Mean age of patients: 67.5±16 years; 49% were males and 51% females. Cause of respiratory failure was cardiovascular surgery in 27%; other surgery in 15.5%; COPD in 21%; pneumonia in 9%; ARDS in 5.5%; neurological disease in 18.5% and heart failure in 3.5%. Sixty-four percent were liberated and 36% failed-to-wean. The studied parameters and outcome in the 2 groups of patients are shown in Table 1.
ParametersWeanedFailedpBUN (mg/dL)29±1733±210.003Cr (mg/dL)0.85±0.90.84±0.50.7CrCl (ml/min)69.3±3561±320.0001RUCr mg/dL43±2844±280.824UCr (mg)646±284593±2620.009
Renal function as measured by BUN, CrCl, and 24-UCr has a statistically significant impact on weaning from PMV. Serum creatinine, by itself, doesnot appear to affect weaning.
Renal function as measured by BUN, CrCl and 24-UCr can be used to prognosticate liberation form PMV. Apart from renal function, BUN and 24-UCr provide an estimate of patients’ nutritional status and positive nitrogen balance, which could also affect weaning outcome.
D. Datta, None.