Does adding sigh breaths to the usual care of trauma patients receiving mechanical ventilation increase ventilator-free days?

By Pooja Toshniwal PahariaReviewed by Danielle Ellis, B.Sc.Oct 30 2023

In a recent study published in JAMA, researchers investigated whether adding sigh breaths to standard care regimens of mechanically ventilated trauma patients increased ventilator-free days (VFDs).

Background

Among mechanical ventilation recipients, tidal volumes are similar or constant with each breath, leading to pulmonary damage induced by ventilators by altering surfactant levels. Studies have indicated that yawns and deep breaths increase surfactant concentrations at the alveolar lining, and occasional maximal inflation by deep breaths could prevent alveolar lining collapse.

Short-term sigh breaths improve gas exchange and compliance while decreasing regional pulmonary strain and ventilation heterogeneity, reversing and preventing atelectasis, and reducing the production of pro-inflammatory cytokines. Recent research has indicated that sighs are safe for administration to lung injury patients.

However, the therapeutic benefit of sigh breaths for preventing ventilator-induced pulmonary damage in trauma patients susceptible to poor disease outcomes is not known, warranting further research.

About the study

In the present study, researchers evaluated the impact of sigh breath addition on clinical outcomes.

The pragmatic SiVent Randomized Clinical Trial (RCT) was conducted between April 2016 and September 2022, including adult trauma patients with an increased risk of acute respiratory distress syndrome (ARDS) development, i.e., those with traumatic brain injuries, those with >1.0 long bone fractures, those with shock (systolic-type blood pressure below 90 mm of Hg at first evaluation), those with lung contusion (stated in the health records), and those who received >6.0 units of hematological products within the initial day of care.

All participants were mechanically ventilated due to trauma for <1.0 days and were predicted to survive beyond two days. The intervention group received sigh breaths in volumes generating 35 cm of H2O plateau pressures [or 40 cm of H2O for trauma inpatients having body mass index (BMI) values above 35] delivered every six minutes, in addition to the treating physician-directed standard care therapy. The control group received standard care treatment only. Individuals were randomized to the groups in a 1:1 ratio.

The primary study outcome was VFDs, i.e., the duration of unaided breathing through four weeks without requiring invasive ventilation reinstitution. Secondary study outcomes included complications, the number of intensive care unit (ICU)-free days in four weeks, discharge status, and all-cause deaths within four weeks. The team performed post-hoc analyses on ventilation-free duration, stratified by demographics, factors increasing ARDS risk, and the extent of injury. The participants were followed up for four weeks across 15 trauma centers in the United States (US). Ethnicity and race data were either self-reported or obtained from medical records.

The team excluded individuals aged <18 years, those who were mechanically ventilated for >24 hours, those with cancer or irreversible diseases with a six-month mortality exceeding 50%, moribund patients, pregnant women, and prisoners.

In addition, individuals with neurologic conditions affecting spontaneous ventilation, those with burns involving a body surface area of >40%, those receiving airway pressure-release ventilation, and those not likely to need mechanical ventilation beyond 24 hours were also excluded.

Results

A total of 5,753 trauma patients were screened, of which 524 were randomized [mean age of 44 years, and 75% (n=394) were men] into the intervention (n=261) and control (n=263) groups. Among intervention group participants with adequate follow-up data available (n=259), 223 received an initial (first day) sigh volume (mean) of 939 mL, or 14 mL per kg of body weight, denoting 195% of their predetermined tidal volume (VT).

The median VFD values in the intervention and control groups were 18 days and 16 days, respectively, with unadjusted and adjusted mean differences of two and 1.4 days. Although unadjusted for multiple tests, sigh breaths were linked to improved secondary outcomes, such as all-cause deaths, with no evidence of harm. The intervention group demonstrated a shorter duration till successful extubation. The median values for the total VFDs (TVFDs) in the intervention and control groups were 20 days and 17 days, respectively. The sigh group had more ventilation-free days in the post-hoc subgroups analyzed with non-significant links between the assigned treatment and subgroups.

The four-week mortality rate in the intervention group was 12% (30 out of 259) versus 18% (46 out of 261) among standard care recipients. There were no significant differences in non-fatal adverse events between the intervention [80 of 259 (31%)] and control groups [80 of 261 (31%)]. The adjusted and unadjusted hazard ratio values for sigh-related deaths compared to standard care therapy were 0.7 and 0.6, respectively. The median ICU-free duration in the intervention and control groups were 14 days and 12 days, respectively. Complication incidence, discharge status, time to develop diffuse or bilateral ARDS infiltrates, and arterial oxygen partial pressure/fractional inspired oxygen (Pao2/FiO2) ratios were comparable in both groups.

Conclusion

Overall, the study findings showed that sigh breaths added to standard care did not significantly increase the ventilator-free period among mechanically ventilated trauma patients at an increased risk of ARDS but improved four-week mortality outcomes.