Purpose: We evaluated characteristics associated with neuromuscular blockade (NMB) use, center-level variation, and whether NMB mediated excess mortality among patients assigned to high-frequency oscillatory ventilation (HFOV) in the OSCILLATE trial.
Materials and methods: NMB exposure was defined as receipt after randomization; the primary outcome was hospital mortality. Descriptive analyses compared NMB-exposed vs unexposed patients. Multivariable analyses included patients not on baseline NMB. Cox regression evaluated associations of patient- and center-level variables with NMB use. A log-normal frailty model evaluated center effects. Mediation analysis examined the effect of NMB in HFOV-assigned patients.
Results: 376/548 patients (39 centers) received post-randomization NMB, of whom 165 received baseline NMB. Patients receiving post-randomization NMB (vs. not) had worse lung mechanics and gas exchange, received more sedation and vasopressors (p < 0.05), and had higher hospital mortality (44% vs. 34%, p = 0.03). Mean airway pressure ≥ 24 cmH2O, randomization to HFOV, and intensive care unit size ≥ 31 beds were associated with post-randomization NMB. After adjustment, center had a negligible effect on post-randomization NMB (median hazard ratio 1.01, p = 0.047). NMB use did not mediate excess mortality among HFOV-allocated patients (p = 0.80).
Conclusions: In OSCILLATE, receipt of post-randomization NMB was associated with worse outcomes, but NMB use did not mediate HFOV-associated higher mortality.
Keywords: Center-level variation; High-frequency oscillatory ventilation; Mediation analysis; Neuromuscular blocker; Secondary analysis of randomized controlled trial.
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