Sigh Ventilation in Patients With Trauma: The SiVent Randomized Clinical Trial

Abstract

Importance: Among patients receiving mechanical ventilation, tidal volumes with each breath are often constant or similar. This may lead to ventilator-induced lung injury by altering or depleting surfactant. The role of sigh breaths in reducing ventilator-induced lung injury among trauma patients at risk of poor outcomes is unknown.

Objective: To determine whether adding sigh breaths improves clinical outcomes.

Design, setting, and participants: A pragmatic, randomized trial of sigh breaths plus usual care conducted from 2016 to 2022 with 28-day follow-up in 15 academic trauma centers in the US. Inclusion criteria were age older than 18 years, mechanical ventilation because of trauma for less than 24 hours, 1 or more of 5 risk factors for developing acute respiratory distress syndrome, expected duration of ventilation longer than 24 hours, and predicted survival longer than 48 hours.

Interventions: Sigh volumes producing plateau pressures of 35 cm H2O (or 40 cm H2O for inpatients with body mass indexes >35) delivered once every 6 minutes. Usual care was defined as the patient's physician(s) treating the patient as they wished.

Main outcomes and measures: The primary outcome was ventilator-free days. Prespecified secondary outcomes included all-cause 28-day mortality.

Results: Of 5753 patients screened, 524 were enrolled (mean [SD] age, 43.9 [19.2] years; 394 [75.2%] were male). The median ventilator-free days was 18.4 (IQR, 7.0-25.2) in patients randomized to sighs and 16.1 (IQR, 1.1-24.4) in those receiving usual care alone (P = .08). The unadjusted mean difference in ventilator-free days between groups was 1.9 days (95% CI, 0.1 to 3.6) and the prespecified adjusted mean difference was 1.4 days (95% CI, -0.2 to 3.0). For the prespecified secondary outcome, patients randomized to sighs had 28-day mortality of 11.6% (30/259) vs 17.6% (46/261) in those receiving usual care (P = .05). No differences were observed in nonfatal adverse events comparing patients with sighs (80/259 [30.9%]) vs those without (80/261 [30.7%]).

Conclusions and relevance: In a pragmatic, randomized trial among trauma patients receiving mechanical ventilation with risk factors for developing acute respiratory distress syndrome, the addition of sigh breaths did not significantly increase ventilator-free days. Prespecified secondary outcome data suggest that sighs are well-tolerated and may improve clinical outcomes.

Trial registration: ClinicalTrials.gov Identifier: NCT02582957.

Figure 1.. Screening, Randomization, and Follow-Up of Participants in the SiVent Trial

MV indicates mechanical ventilation; SiVent, Sigh Ventilation to Increase Ventilator-Free Days in Victims of Trauma at Risk for Acute Respiratory Distress Syndrome. ^aIndividuals may have met more than 1 exclusion criteria. ^bSix individuals were receiving mechanical ventilation. ^cFour individuals temporarily received sighs. ^dVital status at day 28 unknown.

Figure 2.. Kaplan-Meier Estimates of the Probability of Survival and Survival Without the Need for Assisted Ventilation During the First 28 Days After Randomization

Successful extubation was defined as the patient being able to breathe unassisted and maintaining unassisted breathing until the end of the study period. Among those who died, the median days from randomization to death was 5.5 (IQR, 2.1-9.8; n = 30) in the sighs plus usual care group and 5.3 (IQR, 3.5-9.1; n = 46) in the usual care alone group. Among those who were successfully extubated, the median days from randomization to extubation was 6.4 (IQR, 1.9-12.9; n = 209) in the sighs plus usual care group and 6.8 (IQR, 2.8-13.2; n = 197) in the usual care alone group.