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Increased Ratio of Dead Space to Tidal Volume in Subjects With Inhalation Injury
Journal article   Open access   Peer reviewed

Increased Ratio of Dead Space to Tidal Volume in Subjects With Inhalation Injury

Thomas Granchi, Ashley Lemere, Neil Mashruwala, Colette Galet and Kathleen S Romanowski
Respiratory care, Vol.65(10), pp.1555-1560
10/2020
DOI: 10.4187/respcare.07515
PMID: 32665425
url
https://doi.org/10.4187/respcare.07515View
Published (Version of record) Open Access

Abstract

Inhalation injury increases morbidity and mortality in burn patients. Patients with inhalation injury present with large differences between end-tidal CO pressure and [Formula: see text], an indirect measure of dead space. We aimed to investigate the relationships between increased dead space and inhalation injury outcomes. 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 CO pressure, presence of ventilator-associated pneumonia, and mortality data were collected. Modified Baux scores and ratios of alveolar dead space to alveolar tidal volume ([Formula: see text]/[Formula: see text]) were calculated. Independent tests were used to compare mean [Formula: see text]/[Formula: see text] of survivors to that of subjects who died and between subjects with and without pneumonia. The relationships between [Formula: see text]/[Formula: see text] and ventilator days or modified Baux score were assessed with bivariate correlation analysis. 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 [Formula: see text]/[Formula: see text] was 0.38. Ten subjects died, and 6 subjects had pneumonia. The [Formula: see text]/[Formula: see text] of survivors was significantly smaller for survivors than for subjects who died (0.34 vs 0.52, = .03). No significant difference was observed between subjects with and without pneumonia (0.36 vs 0.47, = .26). [Formula: see text]/[Formula: see text] correlated significantly with modified Baux score (r = .524, < .001). Alveolar dead space ([Formula: see text]/[Formula: see text]) is easily calculated from [Formula: see text] and end-tidal CO pressure and may be useful in assessing severity of inhalation injury, the patient's prognosis, and the patient's response to treatment.
 Burns Humans Prognosis Respiratory System - injuries Retrospective Studies Tidal Volume

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