Which is the most serious adverse effect of neuromuscular blocking agents?

• A. Nausea
• B. Bronchospasm
• C. Laryngospasm
• D. Weak chest-wall movement

Answer: (D)

The main risk from neuromuscular blocking agents is the inability to move the muscles used for breathing. When respiratory muscles including the diaphragm and chest wall are paralyzed, ventilation collapses because the patient cannot generate adequate breaths. This leads to insufficient oxygen delivery and rising carbon dioxide, which can cause rapid deterioration without immediate ventilatory support. While events like laryngospasm or bronchospasm are serious and require urgent management, they do not inherently result in total loss of ventilatory effort the way complete chest-wall paralysis does. Nausea is a non-threatening side effect in comparison. So, the most serious adverse effect is the weak chest-wall movement indicating respiratory muscle paralysis and risk of apnea.