RT Journal Article
SR Electronic
T1 Increased Ratio of Dead Space to Tidal Volume in Subjects With Inhalation Injury
JF Respiratory Care
FD American Association for Respiratory Care
SP respcare.07515
DO 10.4187/respcare.07515
A1 Thomas Granchi
A1 Ashley Lemere
A1 Neil Mashruwala
A1 Colette Galet
A1 Kathleen S Romanowski
YR 2020
UL http://rc.rcjournal.com/content/early/2020/07/14/respcare.07515.abstract
AB BACKGROUND: Inhalation injury increases morbidity and mortality in burn patients. Patients with inhalation injury present with large differences between end-tidal CO2 pressure and PaCO2, 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 (VDalv/VTalv) were calculated. Independent t tests were used to compare mean VDalv/VTalv of survivors to that of subjects who died and between subjects with and without pneumonia. The relationships between VDalv/VTalv 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 VDalv/VTalv was 0.38. Ten subjects died, and 6 subjects had pneumonia. The VDalv/VTalv 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). VDalv/VTalv correlated significantly with modified Baux score (r = .524, P < .001).CONCLUSIONS: Alveolar dead space (VDalv/VTalv) is easily calculated from PaCO2 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.