BACKGROUND:
Inhalation injury increases morbidity and mortality in burn patients. Patients with inhalation injury present with large differences between end-tidal CO2 pressure and
, an indirect measure of dead space. We aimed to investigate the relationships between increased dead space and inhalation injury outcomes.
METHODS:
This retrospective study included 51 adult subjects with burns and inhalation injuries. Demographics, size of burns, length of stay, ventilator days, blood gas results, end-tidal CO2 pressure, presence of ventilator-associated pneumonia, and mortality data were collected. Modified Baux scores and ratios of alveolar dead space to alveolar tidal volume (
/
) were calculated. Independent t tests were used to compare mean
/
of survivors to that of subjects who died and between subjects with and without pneumonia. The relationships between
/
and ventilator days or modified Baux score were assessed with bivariate correlation analysis.
RESULTS:
Our population had a mean age of 52 y and an average burn size of 17.5%. The average length of stay and ventilator days were 12 d and 3.8 d, respectively. The mean modified Baux score was 87. The mean
/
was 0.38. Ten subjects died, and 6 subjects had pneumonia. The
/
of survivors was significantly smaller for survivors than for subjects who died (0.34 vs 0.52, P = .03). No significant difference was observed between subjects with and without pneumonia (0.36 vs 0.47, P = .26).
/
correlated significantly with modified Baux score (r = .524, P < .001).
CONCLUSIONS:
Alveolar dead space (
/
) is easily calculated from
and end-tidal CO2 pressure and may be useful in assessing severity of inhalation injury, the patient’s prognosis, and the patient’s response to treatment.
