Authors: Hameed J et al.
Cureus. 17(12): e98230, December 01, 2025. DOI: 10.7759/cureus.98230
Summary:
This retrospective cohort study examined how ventilatory mechanics and dead-space surrogates relate to outcomes in adults with traumatic flail chest requiring invasive ventilation. Because flail chest profoundly disrupts chest wall mechanics and gas exchange, the authors hypothesized that bedside indices combining mechanics (driving pressure, dynamic compliance) and perfusion efficiency (dead-space burden via alveolar dead-space fraction or ventilatory ratio) may be more informative than oxygenation alone when titrating ventilator settings.
The study included 272 mechanically ventilated adults with radiographically confirmed flail chest admitted to a trauma ICU in Peshawar, Pakistan (March 2024–February 2025). Nearly half (49.3%) had elevated dead space (AVDSf ≥0.25 or VR ≥1.5). ICU mortality was 19.9% overall but was nearly three times higher in those with high dead space (29.9% vs. 10.1%). After multivariable adjustment, high dead space remained strongly associated with mortality (aOR 2.21).
Worsening mechanics were also linked to mortality: each 1-cmH₂O increase in driving pressure raised mortality risk (aOR 1.05), while each 10-mL/cmH₂O increase in dynamic compliance reduced mortality (aOR 0.82). Patients with high dead space had fewer ventilator-free days by day 28 and longer ICU stays. Driving pressure also tracked with barotrauma risk; a +5 cmH₂O increase increased barotrauma subhazard by approximately 58%.
Overall, the findings suggest that flail-chest physiology may be better managed by incorporating dead-space metrics and driving-pressure monitoring into ventilator strategies rather than relying primarily on oxygenation indices. The authors propose a practical bundle: routinely calculate VR or AVDSf, target VR <1.5, and maintain driving pressure in the low teens (≤14 cmH₂O) while ensuring adequate perfusion. These strategies may complement regional analgesia and surgical stabilization to improve outcomes, though prospective validation is needed.
What You Should Know
• High dead space—measured by AVDSf or ventilatory ratio—was common (~50%) and strongly predicted ICU mortality.
• Driving pressure was a key modifiable parameter: small increases correlated with higher mortality and barotrauma.
• Better lung mechanics (higher dynamic compliance) were associated with improved survival.
• High dead space also predicted lower ventilator-free days and longer ICU stays.
• Findings support integrating dead-space measures with mechanical indices to guide ventilation in flail chest, rather than relying solely on oxygenation metrics.
• A practical bedside target bundle may include driving pressure ≤14 cmH₂O and VR <1.5 when achievable.
Key Points
• Dead-space burden is a powerful prognostic marker in ventilated flail-chest patients.
• Driving pressure and dynamic compliance independently correlate with survival.
• Barotrauma risk rises as driving pressure increases.
• Mechanical-perfusion indices can help standardize ventilator management in trauma ICUs.
• Prospective trials are needed to validate these targets.
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