Mechanical ventilation and fluid retention in burn patients.

BACKGROUND

Burn patients with inhalation injury (INHI) require more fluid resuscitation than patients without INHI. However, the relation between INHI and fluid resuscitation may be confounded by a ventilation-induced increase in fluid retention. We therefore evaluated whether INHI was independently of continuous positive pressure ventilation (CPPV) associated with increased fluid retention.

METHODS

One hundred eighty-six patients with burns of >20% of total body surface area admitted to the Beverwijk Burns Center (1995-2006) were retrospectively studied. Cumulative fluid balance, defined as the total volume of fluids administered from the time of admission minus the total volume of fluids collected from each patient, was calculated at the end of days 3 (FB3) and 7 (FB7) postburn. The population was divided into three groups: (1) INHI-CPPV- (no INHI, no ventilation; n = 75); (2) INHI-CPPV+ (no INHI with ventilation; n = 62); and (3) INHI+CPPV+ (INHI with ventilation; n = 49). Analyses were corrected for differences in age, weight, and % total body surface area.

RESULTS

Patients who were mechanically ventilated were older and had more extensive burns than those who were not ventilated. Baseline characteristics of patients without INHI who were treated by CPPV were similar to patients with INHI, also treated by CPPV. FB3 was significantly higher in patients without INHI who were ventilated compared with nonventilated patients (13.4 +/- 5.8 L vs. 23.1 +/- 10.6 L for INHI-CPPV- and INHI-CPPV+ respectively, p = 0.001). However, fluid balance was not additionally affected by the presence of INHI. The difference in fluid retention between nonventilated and ventilated patients was also seen on day 7 (22.1 +/- 9.4 L vs. 34.2 +/- 15.9 L for INHI-CPPV- and INHI-CPPV+, respectively, p = 0.001).

CONCLUSION

These results suggest that increased fluid retention, which is conventionally associated with INHI, is due to the effects of ventilation and not to the effects of INHI itself. This warrants a closer evaluation of patients who are ventilated in the absence of INHI, with a view to early extubation.