🫁 Transition Phase in ARDS: Predictors of NMBA and PSV Failure
Abstract: Protective ventilation and liberation strategies in ARDS are well established, but the transition phase—between stopping neuromuscular blockade (NMBA) and initiating assisted ventilation—remains poorly defined. This bicentric cohort study (n=196) evaluated predictors of NMBA weaning failure and pressure support ventilation (PSV) failure, focusing on the impact of tidal volume.
Key Insights
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NMBA weaning failure: Occurred in 38% of patients, mainly for asynchrony/respiratory distress, hypoxemia, or prone positioning needs .
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Risk factors: Independent predictors included COVID-19 ARDS (OR 3.98), low (<12 cmH₂O) or high (≥14 cmH₂O) driving pressure (OR 2.77), acidemia (pH <7.30, OR 0.50), and PaO₂/FiO₂ <150 mmHg (OR 0.92) .
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PSV initiation: Tried in 75% of patients; 57% failed within a median of 9 hours, requiring return to assist-control ventilation .
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PSV risk factor: High tidal volume (>9.3 mL/kg PBW) was independently linked to PSV failure (OR 1.28, specificity 91%) .
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Prevalence of high tidal volumes: 43% of patients on PSV had >8 mL/kg PBW, with mortality highest in those exceeding 10 mL/kg .
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Double failures: 41 patients failed both NMBA weaning and PSV; they had higher mortality (34% vs 16%) .
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Mechanistic insights: Findings support the concept of patient self-inflicted lung injury (P-SILI) driven by high effort and uncontrolled tidal volumes during transition.
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Clinical caution: Premature NMBA withdrawal in patients with severe hypoxemia or acidemia may worsen outcomes.
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Research need: The transition phase represents a critical, understudied window, demanding prospective trials to optimize protocols and minimize risk.
Conclusion
The transition phase in ARDS is a high-risk period. Nearly 4 in 10 fail NMBA weaning and over half fail PSV, with failures strongly tied to worse outcomes. Tidal volume during PSV emerges as a key prognostic marker. Tailored strategies to manage effort, avoid premature NMBA withdrawal, and limit injurious tidal volumes are urgently needed.
Take-Home for Clinicians
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Be vigilant for acidemia and severe hypoxemia before NMBA withdrawal.
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Monitor driving pressure closely; extremes predict failure.
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Keep PSV tidal volume <9 mL/kg PBW to reduce failure and mortality risk.
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Recognize the transition phase as a unique target for protocol development.
Discussion Question: Should ICUs adopt standardized protocols for the transition phase in ARDS—similar to protective ventilation and weaning guidelines—to reduce preventable failures and P-SILI?
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