Which pharmaceutical agent should not be used during a bronchoscopy when a child is coughing?

During a bronchoscopy, it is crucial to ensure that the airway remains clear and manageable, especially if the child is coughing. Succinylcholine is a neuromuscular blocker that causes paralysis by interfering with muscle contraction. While it can be useful in facilitating intubation or surgical procedures where muscle relaxation is necessary, its use in a situation involving coughing is contraindicated because it does not suppress the cough reflex or address the underlying airway irritation.

Using succinylcholine during a bronchoscopy may result in a failure to maintain protective airway reflexes, which can lead to aspiration or injury to the airway. The cough reflex is an important protective mechanism during procedures involving the respiratory tract, and suppressing all muscle function, including the diaphragm, can result in significant respiratory complications, especially if the child is still prone to coughing.

In contrast, agents such as cetacaine can be used topically for local anesthesia, racemic epinephrine has vasoconstrictive properties and can reduce airway swelling, and ketamine provides analgesia and sedation without significantly compromising respiratory function. Thus, succinylcholine is the least appropriate choice in this context.