Risks of Neuromuscular Blockade

Neuromuscular blocking agents (NMBAs) are used to relieve anxiety and pain and paralyze the skeletal muscles during surgery. Stress responses to anxiety and pain can suppress the immune system, affect the heart and lungs and increase risks of injury and death, says Jill Luer, medical director at Helix Medical Communications.



Neuromuscular blockades are used in emergency departments, intensive care units, radiology and surgical units. Because they leave the patient unable to breathe or move, NMBAs carry high risks, report pharmaceutical scientists Manish Pal Singh, Ragvendra Singh Bhaduaria and C.S. Sharma in "Neuromuscular Blocking Agents (NMBAs): An Overview."

Medical Errors

• Medical errors occur with the use of NMBAs 16 to 37 percent of the time.

  One of the most significant risks of neuromuscular blockade drugs, according to the pharmaceutical scientists, is medical error. In Pennsylvania, for instance, 154 medical error reports were filed between 2004 and 2009. Wrong drugs were given 37 percent of the time and wrong dosages of NMBAs were given over 16 percent of cases.

Anaphylaxis

• Severe allergic reactions can occur with the use of NMBAs.

  Anaphylaxis is a severe allergic reaction that is often unpredictable. In "Anaphylaxis to Muscle Relaxants," Professor Marie-Claire Laxenaire says that NMBAs cause 50 to 60 percent of anaphylactic reactions that occur during anesthesia, and that these reactions can be lethal.

Aspiration

• Constant care must be taken to prevent aspiration and suffocation.

  Neuromuscular blockades prevent a patient from breathing on her own. Any failure of a ventilator can prove fatal, warns Karen Tietze in "Chinese Medical & Biological Informatics." NMBAs inhibit the cough reflex so constant suctioning of the endotracheal tube is necessary to prevent aspiration, and the patient's head must remain elevated, especially during feeding.

Blood Clots and Cardiovascular Effects

• Low blood pressure can lead to blood clot formation.

  Neuromuscular blockades lower blood pressure and trigger the release of histamine, which can result in cardiovascular complications, explains Tietze. Lowered blood pressure can increase the risk of blood clots so deep vein therapy is necessary with the use of NMBAs.

Prolonged Paralysis

• Electrical stimulation can help prevent muscle cell death.

  Another risk associated with neuromuscular blockades is prolonged paralysis. Tietze explains that this paralysis may occur because of the accumulation of the drugs in the body or because of muscle cell death.

  If a patient's kidneys aren't clearing the NMBAs properly, the paralysis can remain for up to one week after discontinuing the drugs. Most reports of muscle death occur when NMBAs are combined with corticosteroids, but Tietze advises that it can also occur with the use of NMBAs alone. Nerve stimulation can reduce these effects.

  Prolonged paralysis occurs in 5 to 10 percent of patients who undergo neuromuscular blockades for over 24 hours, says Tietze. Antibiotics, calcium channel blockers and magnesium can increase the risk of prolonged paralysis, according to "Emerging Considerations in the Reversal of Neuromuscular Blockade and Residual Block," by researchers Wayne Nicholson, Juraj Sprung and Christopher Jankowski. They warn of the potential serious adverse events such as respiratory depression, problems with the pharynx and low oxygen levels.

  The use of acetylcholinesterase inhibitors or the drug sugammadex can reverse the effects of a neuromuscular blockade.