Mechanical Ventilation and Acute Lung Injury in Emergency Department Patients With Severe Sepsis and Septic Shock: An Observational Study

Abstract

Objectives To characterize the use of mechanical ventilation in the emergency department (ED), with respect to ventilator settings, monitoring, and titration; and to determine the incidence of progression to acute lung injury (ALI) after admission, examining the influence of factors present in the ED on ALI progression. Methods This was a retrospective, observational cohort study of mechanically ventilated patients with severe sepsis and septic shock (June 2005 to May 2010), presenting to an academic ED with an annual census of >95,000 patients. All patients in the study (n = 251) were analyzed for characterization of mechanical ventilation use in the ED. The primary outcome variable of interest was the incidence of ALI progression after ICU admission from the ED and risk factors present in the ED associated with this outcome. Secondary analyses included ALI present in the ED and clinical outcomes comparing all patients progressing to ALI versus no ALI. To assess predictors of progression to ALI, statistically significant variables in univariable analyses at a p ≤ 0.10 level were candidates for inclusion in a bidirectional, stepwise, multivariable logistic regression analysis. Results Lung-protective ventilation was used in 68 patients (27.1%), and did not differ based on ALI status. Delivered tidal volume was highly variable, with a median tidal volume delivered of 8.8 mL/kg ideal body weight (IBW) (IQR 7.8 to 10.0), and a range of 5.2 to 14.6 mL/kg IBW. Sixty-nine patients (27.5%) in the entire cohort progressed to ALI after admission to the hospital, with a mean onset of 2.1 days (SD ± 1 day). Multivariable logistic regression analysis demonstrated that a higher body mass index, higher Sequential Organ Failure Assessment score, and ED vasopressor use were associated with progression to ALI. There was no association between ED ventilator settings and progression to ALI. Compared to patients who did not progress to ALI, patients progressing to ALI after admission from the ED had an increase in mechanical ventilator duration, vasopressor dependence, and hospital length of stay. Conclusions Lung-protective ventilation is uncommon in the ED, regardless of ALI status. Given the frequency of ALI in the ED, the progression shortly after ICU admission, and the clinical consequences of this syndrome, the effect of ED-based interventions aimed at reducing the sequelae of ALI should be investigated further.

Mechanical Ventilation and ARDS in the ED

“…14 The current investigation shows a decrease of about 1 mL/kg PBW and overall less variability in practice. However, a signifi cant percentage of patients remain exposed to high tidal volumes while in the ED.…”

“…Based on previous existing data, our sample size was recognized as likely to be adequate for investigation of ED-based parameters associated with progression to ARDS. 14,47 Th e analysis was conducted in consultation with a biostatistician.…”

“…19 We did not include a pressure limit to defi ne lung protective, because previous data suggest monitoring of inspiratory plateau pressure is rare in intubated patients in the ED. 14 …”

“…[4][5][6][7][8][9][10][11][12][13] Despite these trends, there remain relatively few data on ED-based mechanical ventilation practices. 14 ARDS exacts a signifi cant toll on patients who are mechanically ventilated in terms of mortality, long-term survivor morbidity, and health-care use. 15,16 Compared with those in the ICU, ARDS data in the ED population are sparse.…”

“…Observational studies indicate an ARDS prevalence of approximately 9% in patients receiving mechanical ventilation in the ED. 14,17,18 Most of these data, however, are restricted to a narrow cohort of patients (ie, those with sepsis) and are singlecenter investigations.…”