Abstract
BACKGROUND: The management of mechanical ventilation critically impacts outcome for patients with acute respiratory failure. Ventilator settings in the early post-intubation period may be especially influential on outcome. Low tidal volume ventilation in the prehospital setting has been shown to impact the provision of low tidal volume after admission and influence outcome. However, there is an overall paucity of data on mechanical ventilation for air medical transport patients. The objectives of this study were to characterize air medical transport ventilation practices and assess variables associated with nonprotective ventilation.
METHODS: This was a multi-center, nationwide (approximately 130 bases) retrospective cohort study conducted on consecutive, adult mechanically ventilated air medical transport patients treated in the prehospital environment. Descriptive statistics were used to assess the cohort; the chi-square test compared categorical variables, and continuous variables were compared using independent samples t test or Mann-Whitney U test. To assess for predictors of nonprotective ventilation, a multivariable logistic regression model was constructed to adjust for potentially confounding variables. Low tidal volume ventilation was defined as a tidal volume of ≤ 8 mL/kg predicted body weight (PBW).
RESULTS: A total of 68,365 subjects were studied. Height was documented in only 4,186 (6.1%) subjects. Significantly higher tidal volume/PBW (8.6 [8.3–9.2] mL vs 6.5 [6.1–7.0] mL) and plateau pressure (20.0 [16.5–25.0] cm H2O vs 18.0 [15.0–22.0] cm H2O) were seen in the nonpro-tective ventilation group (P < .001 for both). According to sex, females received higher tidal volume/PBW compared to males (7.4 [6.6–8.0] mL vs 6.4 [6.0–6.8] mL, P < .001) and composed 75% of those subjects with nonprotective ventilation compared to 25% male, P < .001. After multivariable logistic regression, female sex was an independent predictor of nonprotective ventilation (adjusted odds ratio 6.79 [95% CI 5.47–8.43], P < .001).
CONCLUSIONS: The overwhelming majority of air medical transport subjects had tidal volume set empirically, which may be exposing patients to nonprotective ventilator settings. Given a lack of PBW assessments, the frequency of low tidal volume use remains unknown. Performance improvement initiatives aimed at indexing tidal volume to PBW are easy targets to improve the delivery of mechanical ventilation in the prehospital arena, especially for females.
- mechanical ventilation
- prehospital
- lung-protective ventilation
- air medical transport
Footnotes
- Correspondence: Brian M Fuller MD MSCI, Departments of Anesthesiology and Emergency Medicine, Division of Critical Care, Washington University School of Medicine, Washington University in St. Louis, St. Louis, MO 63110. E-mail: fullerb{at}wustl.edu
See the Related Editorial on Page 774
The authors have disclosed no conflicts of interest.
A version of this paper was presented by Dr Fuller at SCCM 2022, held virtually April 18–21, 2022. Some of the demographic data were also used in a manuscript that was focused on prehospital sedation practices, which has been accepted for publication in Critical Care Explorations.
Dr Kollef is supported by the Barnes-Jewish Hospital Foundation. Dr Fuller is supported by the National Heart, Lung, and Blood Institute of the National Institutes of Health under award number R34HL150404. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH. Funders played no role in the features of the study.
This study was performed at Washington University School of Medicine, Washington University in St. Louis, St. Louis, Missouri.
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