Neuromuscular Blockade in the Optimal Management of Mechanical Ventilation of Patients with Respiratory Distress

Ross      Freebairn; Gerard      McHugh

Abstract

Mechanical ventilation is an integral component in the management of patients with acute respiratory failure. The role of neuromuscular junction blocking agents (NMBA) in facilitating mechanical ventilation in intensive care remains controversial. NMBA have been variously advocated to decrease oxygen consumption through reduction of the work of breathing, ablation of shivering and reduction of metabolic rates, as well as to increase oxygen delivery through improved ventilation. Additional attributed benefits include the reduced potential for barotrauma, enhanced ventilatorpatient synchrony, and an ability to reduce the inspired fraction of oxygen. Despite all of these putative benefits, there remains scant high-grade evidence to guide rationale use of NMBA in the critically ill patient. Many Clinical Practice Guidelines recommend that NMBA be avoided due to the associated risk of prolonged neuromuscular weakness. Other adverse effects associated with NMBA use include the consequences of undetected circuit disconnection, reduced neurological signs, risk of awareness and recall in inadequately sedated patients, increased post-traumatic stress disorder, and reduction in supported spontaneous breathing and coughing.

Optimal paralysis depth remains empiric and is often poorly controlled or monitored in intensive care. Nonetheless prudent NMBA does not appear to prolong ventilation. Refractory hypoxemia almost invariably leads to the use of NMBA. Intriguingly, systematic use of NMBA for 48 hours appears to have beneficial long-term effects in patients with severe ARDS. Rather than simply targeting short term gain in oxygenation and lung mechanics, this benefit may justify a 2-day period of NMBA use in severe ARDS.

Keywords: Neuromuscular, paralysis, relaxant, blockade, acute respiratory distress syndrome, awareness, post traumatic stress disorder, ventilation, intensive care, oxygenation, NMBA, barotrauma, ARDS, acute lung injury, inherent toxicity, anaesthesia, PTSD, tracheostomy tube, PEEP, polyneuropathy, polymyopathy, polymyon-europathy, COPD, muscle atrophy, ALVEOLI, cardiopulmonary bypass, morphine, midazolam, placebo, asynchrony, ventilator-induced lung injury, (VILI), APRV