Why is neuromuscular blockade (paralysis) used in a patient with brain death and Acute Respiratory Distress Syndrome (ARDS)?

From the Guidelines

Neuromuscular blockade is not generally recommended for brain-dead patients with ARDS, as it offers limited benefits in this scenario, but may be considered in rare cases where persistent spinal reflexes interfere with mechanical ventilation. Brain-dead patients do not have voluntary movement, so the primary reason for paralysis - to improve ventilator synchrony and oxygenation - is not applicable. However, the use of neuromuscular blocking agents (NMBAs) like cisatracurium has been shown to improve oxygenation and reduce mortality in patients with ARDS, as seen in a study published in Critical Care Medicine in 2016 1. This study found that a 48-hour cisatracurium infusion reduced the risk of death at 28 days and at hospital discharge, and reduced the risk of barotrauma, in patients with ARDS.

The mechanism of benefit of neuromuscular blockade in ARDS remains uncertain, but it is thought to prevent ventilator asynchrony and decrease airway pressures and lung stress. If necessary, a neuromuscular blocking agent like cisatracurium could be used, typically at a dose of 0.15-0.2 mg/kg IV bolus, followed by an infusion of 1-2 mcg/kg/min, as suggested by the study 1. The duration should be as short as possible, reassessing frequently. It's crucial to note that paralysis does not provide any benefit to the patient's recovery or organ function in brain death, and the focus should be on maintaining physiological stability for potential organ donation if applicable. Always ensure adequate sedation is in place before administering paralytics, even in brain-dead patients, as a matter of good practice and ethics.

Some studies have suggested that the use of NMBAs may be beneficial in patients with ARDS, even in the absence of brain death, as seen in a study published in Critical Care in 2017 1. This study suggested that the use of NMBAs, such as cisatracurium, may be considered in patients with ARDS who have high plateau airway pressures, in order to reduce the risk of ventilator-induced lung injury. However, the use of NMBAs in brain-dead patients with ARDS should be approached with caution, and the benefits and risks should be carefully weighed.

In terms of the quality of evidence, the study published in Critical Care Medicine in 2016 1 provides moderate-quality evidence for the use of NMBAs in patients with ARDS, while the study published in Critical Care in 2017 1 provides expert opinion-based recommendations. The study published in Critical Care in 2017 1 provides a review of the available clinical evidence related to ventilator support and adjuvant therapies in patients with ARDS, but does not provide specific recommendations for the use of NMBAs in brain-dead patients with ARDS.

Key points to consider when using NMBAs in brain-dead patients with ARDS include:

• The use of NMBAs should be limited to rare cases where persistent spinal reflexes interfere with mechanical ventilation
• The duration of NMBA use should be as short as possible, reassessing frequently
• Adequate sedation should be ensured before administering paralytics, even in brain-dead patients
• The benefits and risks of NMBA use should be carefully weighed, taking into account the individual patient's circumstances.

From the Research

Use of Neuromuscular Blockade in Brain Death and ARDS

• Neuromuscular blockade, or paralysis, is used in patients with brain death and Acute Respiratory Distress Syndrome (ARDS) as part of the management strategy to optimize organ donation 2.
• The primary goal of using neuromuscular blockade in these patients is to facilitate mechanical ventilation and prevent complications that may jeopardize the viability of organs for transplantation 2.
• The use of paralytics, such as neuromuscular blocking agents, is a common practice in the management of organ donors after brain death, as it helps to ensure optimal organ recovery and donation 2.

Rationale for Neuromuscular Blockade

• Brain death is associated with a range of pathophysiological changes, including hemodynamic instability, endocrine and metabolic disturbances, and disruption of internal homeostasis, which can compromise organ function and viability 3, 4, 5.
• The use of neuromuscular blockade can help to mitigate some of these changes by reducing muscle activity and facilitating mechanical ventilation, thereby improving oxygenation and reducing the risk of organ damage 2.
• Additionally, neuromuscular blockade can help to prevent complications such as coughing, bucking, or other movements that may dislodge endotracheal tubes or compromise organ function 2.

Clinical Guidelines and Protocols

• Clinical guidelines and protocols for the management of organ donors after brain death emphasize the importance of optimizing organ function and viability through aggressive donor management, including the use of neuromuscular blockade 3, 4, 5, 2.
• These guidelines and protocols typically include recommendations for the use of medications such as paralytics, vasopressors, and hormone replacement therapy to support organ function and optimize donation outcomes 2.