In the literature, daily weights and fluid intake and output are inaccurately recorded and do not correlate. Reports were published prior to use of electronic medical records and new insights into the effect of fluid status on critical care outcomes. We hypothesized that this data would be more efficiently recorded and would better correlate with each other.
As part of an analysis of mechanically ventilated patients performed to evaluate the relationship between fluid balance and ventilator outcomes, patient weights and net fluid balance were recorded on admission, the day of death or discharge from the hospital.
Net fluid balance (ml/kg/day) and weight changes (mg/kg/day) were recorded for 140 mechanically ventilated patients admitted to the MICU. Fluid balance at hospital discharge ranged from -46.70 to +85.70 ml/kg/day (mean 10.23+/−18.9) while weight change ranged from −24.64 to +79.75 mg/kg/day (mean = 8.41+/−17.51). Net weight change at hospital discharge or death ranged from −29 to +79 kg (mean = 6.029 +/− 16.96 kg). There was correlation between net fluid balance and net weight change (p = 0.002). Patients with a net weight loss had a net fluid balance of +7.941 +/− 25.18 L (range −19.65 to +133.6 L) and patients with a net weight gain had a net fluid balance of +14.20 +/− 17.55 L (range −13.75 to + 79.11 L. The mean difference between fluid weight and the scale weight was 21437 +/−19218 kg (range 0.131 to 133.6 kg) and 66% had a difference > 10.0 kg.
The range of values for both weight change and fluid balance was extreme and not possible physiologically. There was a large discrepancy between them for the majority of patients. They correlate with each other but this has no clinical significance. The ease of documentation using the electronic medical record has improved the frequency of recording but not the accuracy of recording these values.
A reliable system for accurately recording this data needs to be devised given its increasing clinical significance.
Frank Lodeserto, No Financial Disclosure Information; No Product/Research Disclosure Information