Short-term effects of neuromuscular blockade on global and regional lung mechanics, oxygenation and ventilation in pediatric acute hypoxemic respiratory failure.

Marlon E F Wilsterman,Martin C J Kneyber,Sandra K Dijkstra,Inez Frerichs,Johannes G M Burgerhof,Marcel J I J Albers,Robert Blokpoel,Dick G Markhorst,Pauline De Jager

doi:10.1186/s13613-016-0206-9

Abstract

BackgroundNeuromuscular blockade (NMB) has been shown to improve outcome in acute respiratory distress syndrome (ARDS) in adults, challenging maintaining spontaneous breathing when there is severe lung injury. We tested in a prospective physiological study the hypothesis that continuous administration of NMB agents in mechanically ventilated children with severe acute hypoxemic respiratory failure (AHRF) improves the oxygenation index without a redistribution of tidal volume V T toward non-dependent lung zones.MethodsOxygenation index, PaO2/FiO2 ratio, lung mechanics (plateau pressure, mean airway pressure, respiratory system compliance and resistance), hemodynamics (heart rate, central venous and arterial blood pressures), oxygenation [oxygenation index (OI), PaO2/FiO2 and SpO2/FiO2], ventilation (physiological dead space-to-V T ratio) and electrical impedance tomography measured changes in end-expiratory lung volume (EELV), and V T distribution was measured before and 15 min after the start of continuous infusion of rocuronium 1 mg/kg. Patients were ventilated in a time-cycled, pressure-limited mode with pre-set V T. All ventilator settings were not changed during the study.ResultsTwenty-two patients were studied (N = 18 met the criteria for pediatric ARDS). Median age (25–75 interquartile range) was 15 (7.8–77.5) weeks. Pulmonary pathology was present in 77.3%. The median lung injury score was 9 (8–10). The overall median CoV and regional lung filling characteristics were not affected by NMB, indicating no ventilation shift toward the non-dependent lung zones. Regional analysis showed a homogeneous time course of lung inflation during inspiration, indicating no tendency to atelectasis after the introduction of NMB. NMB decreased the mean airway pressure (p = 0.039) and OI (p = 0.039) in all patients. There were no significant changes in lung mechanics, hemodynamics and EELV. Subgroup analysis showed that OI decreased (p = 0.01) and PaO2/FiO2 increased (p = 0.02) in patients with moderate or severe PARDS.ConclusionsNMB resulted in an improved oxygenation index in pediatric patients with AHRF. Distribution of V T and regional lung filling characteristics were not affected.

Highlights

Neuromuscular blockade (NMB) has been shown to improve outcome in acute respiratory distress syndrome (ARDS) in adults, challenging maintaining spontaneous breathing when there is severe lung injury
Severe respiratory failure ranging from acute hypoxemic respiratory failure (AHRF) to acute respiratory distress syndrome (ARDS) is associated with substantial morbidity and mortality in up to 30–50% of critically ill children [1, 2]
Management of these children has been confined to a lung-protective mechanical ventilation (MV) strategy entailing low tidal volume (VT) of 6 mL/kg body weight, limiting peak inspiratory pressure (PIP) and/or plateau pressure (Pplat) to 30 cmH2O and the application of positive end-expiratory pressure (PEEP) [3, 4]

Summary

Introduction

Neuromuscular blockade (NMB) has been shown to improve outcome in acute respiratory distress syndrome (ARDS) in adults, challenging maintaining spontaneous breathing when there is severe lung injury. We tested in a prospective physiological study the hypothesis that continuous administration of NMB agents in mechanically ventilated children with severe acute hypoxemic respiratory failure (AHRF) improves the oxygenation index without a redistribution of tidal volume VT toward non-dependent lung zones. The pathophysiological mechanisms underlying the beneficial effects of short-term use of NMB agents in severe ARDS remain speculative but are most likely multifactorial including a minimization of barotrauma, reduced patient-ventilator asynchrony, prevention of active expiration, decreased lung inflammation and reduced oxygen consumption (V O2) resulting from a decreased work of breathing (WOB) [11,12,13]. Yoshida et al showed the occurrence of pendelluft toward the dependent zones during spontaneous breathing, thereby leading to local overstretch of the dependent lung zones [14]

Objectives

Methods

Results

Discussion

Conclusion