What would be an acceptable anesthetic plan for this patient?
Choice of induction of general anesthesia in a patient with a full stomach is dependent upon several factors, among which is the patient’s airway evaluation. The airway evaluation should always include a thorough history of the patient’s prior intubations, making certain to elicit any his-tory of difficult intubations. If the patient has an acceptable airway, pharmacologic prophylaxis should be administered and preoxygenation/denitrogenation is followed by a rapid sequence induction with cricoid pressure. At the time of induction, there should be an assistant present to provide the cricoid pressure. Suction should be immediately avail-able in case of regurgitation. The induction agent selected should have a rapid predictable onset time. Commonly used agents are thiopental, propofol, etomidate and keta-mine. The muscle relaxant used should also have a fast onset. Classically, the neuromuscular blocking agent used for rapid sequence inductions has been succinylcholine. If, however, succinylcholine is contraindicated for any reason, a fast-onset intermediate-acting neuromuscular blocking agent, such as rocuronium, can be used. When choosing these drugs, the dose must be increased. The disadvantage of using a nondepolarizing neuromuscular blocking agent is that its prolonged action may necessitate prolonged mask ventilation if intubation is unsuccessful.
If intubation is unsuccessful, help from an anesthesia col-league should be called for. Mask ventilation is initiated with cricoid pressure. The peak airway pressures should be kept <20 cm H2O to limit ventilation of the stomach. Ventilation should be continued until the patient awakens. Further muscle relaxant should not be given. If mask ventilation is difficult, ventilation through an LMA is indicated. Intubation through a correctly seated LMA is possible. It is important to remember that both mask ventilation and LMA placement can be impeded by cricoid pressure.
If a difficult intubation is anticipated, either by history or physical examination, a rapid sequence induction is contraindicated. In this case, the most prudent approach would be to do an awake fiberoptic intubation. This poses some unique challenges in the patient with a full stomach. For an awake fiberoptic intubation to be successful, the patient’s airway needs to be well topicalized with local anes-thetic above and below the vocal cords. However, anes-thetizing the entire airway, especially below the vocal cords, will cause a profound loss of all airway reflexes and may increase the risk of aspiration. There are those practitioners who believe that the awake, unsedated patient will know if they are about to vomit and can be encouraged to cough and turn their head to the side. These practitioners will pro-ceed with topicalization of the entire airway. There are others who will only topicalize the airway above the vocal cords in an effort to preserve the tracheal reflexes in the event aspiration occurs. Therefore, topicalization of the air-way is recommended for the patient with a full stomach, but the use of a transtracheal block is user dependent.
An inhalation induction by mask should not be done on a patient with a full stomach, except in specific circum-stances such as a child with epiglottitis.
After the trachea has been intubated with a cuffed endotracheal tube, the anesthetic can be maintained in a number of ways including air/O2, inhalation agent, opioid, and muscle relaxant. Although a cuffed tube will provide more protection than an uncuffed tube, aspiration may still occur around the cuff.
During extubation of the trachea, aspiration may also occur. It is thus imperative that the patient is able to protect their airway before the trachea is extubated. Therefore, the patient should be fully awake, responsive, and sponta-neously breathing.