Muscle Relaxation for Induction in Patients with a Full Stomach

1In onethird of these cases, aspiration occurred at induction of anesthesia and, in 64% of these cases, there was inadequate paralysis at the time of intubation. If a full stomach is suspected, pre-oxygenation is performed to avoid hypoxemia, should ventilation be impossible for several minutes. Then, one proceeds with rapid intravenous induction that includes a neuromuscular blocking agent to limit the interval between anesthesia induction and tracheal intubation to approximately 1 minute (Table 1). The goal is to reduce the time period during which aspiration of gastric contents is possible. However, this sequence of events is associated with 2 major disadvantages: first, the need to inject rapidly does not allow titration of anesthetic agents and, second, the technique carries the risk of failure of both intubation and ventilation (a “can’t intubate, can’t ventilate” scenario). To minimize the risk of aspiration, intubating conditions must be optimal. To achieve this, it is not realistic to depend on large doses of opioid and hypnotic drugs because of the risk of hypotension. In patients presenting for emergency surgery, optimal intubating conditions cannot be obtained unless adequate doses of neuromuscular blocking agents are given. In this issue of Anesthesiology Rounds, discussion is restricted to a case concerning an adult patient with a pre-operative airway exam that suggests no anticipated problems with tracheal intubation. The indications for rapid sequence induction are not discussed, but it is assumed that the anesthesiologist has determined that a rapid sequence induction with tracheal intubation is indicated. Specific cases, such as emergency surgery in children, in pregnant women, and in individuals with elevated intracranial pressure, open eye injuries, or cervical spine trauma, are not covered. HISTORY The relationship between anesthesia and aspiration pneumonia became clear in 1946, when Mendelson, an obstetrician, published a case series of pregnant patients, most of whom had been administered an anesthetic via face mask. This led to the widespread acceptance of pre-operative fasting rules, but this solution did not solve the problem of the patient with slow gastric emptying or when the surgical procedure cannot be delayed. The introduction of succinylcholine in 1951 was a major advance. However, in a British survey on perioperative mortality in the early 1950s, vomiting and regurgitation accounted for as much as 19% of the deaths attributable to anesthesia. 2