Answer:

All the precautions to prevent aspiration of gastric contents and asthmatic attack must be considered simultaneously. Rapid sequence induction and tracheal intubation is necessary to prevent aspiration. However, light anesthesia may precipitate severe bronchospasm.

Prior to induction, inhalation of ₂-agonists such as albuterol should be administered. The patient should then be adequately denitrogenated with 100% oxygen administered by mask. Preoxygenation is particularly important because mask ventilation is usually not performed in rapid sequence induction. Preoxygenation is administered for three minutes of normal VT breathing, or for eight deep breaths over 1 minute.

Propofol is the induction agent of choice in a hemodynamically stable patient with asthma. Ketamine and etomidate are alternatives to propofol in a patient at risk of hemodynamic instability. It is important to note that in a patient with depleted sympathetic reserve, ketamine administration may result in hypotension.

Intravenous lidocaine is a useful adjunct drug to prevent reflex bronchospasm, particularly in emergency situations when deep anesthesia cannot be achieved before intubation (see section C.5).

Traditionally, opioids were not used as part of rapid sequence induction. However, opioids reduce cardiovascular effects associated with laryngoscopy and suppress cough reflex. They also reduce the dose of induction agent required to achieve adequate depth of anesthesia. Therefore, administration of opioids that do not release histamine, such as fentanyl and remifentanil, should be considered.

Muscle relaxant is administered after the induction agent to achieve optimal intubating conditions. Unless contraindicated, succinylcholine should be used because it provides excellent intubating conditions within 30 to 60 seconds of administration. Rocuronium 1.2 mg per kg is an alternative to succinylcholine but results in much longer neuromuscular block.

In a patient with asthma, efforts to achieve adequate depth of anesthesia necessary to minimize bronchospasm may result in hypotension. Therefore, medications to treat hypotension, such as phenylephrine, should be immediately available.