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A1170
October 26, 2005
10:30:00 AM - 12:00:00 PM
Room C305
Use of Low Dose Succinylcholine in Morbidly Obese Patients
Matthew P. Chow, M.D., Gaylord D. Alexander, M.D., Morris Brown, M.D.
Anesthesiology, Henry Ford Health System, Detroit, Michigan, United States
Introduction: Morbidly obese patients are at an increased risk of hypoxemia from prolonged apnea during difficult tracheal intubations. Time to 50% recovery of twitch tension has been used to define functional recovery sufficient to maintain life-sustaining spontaneous ventilation. Thus, time to return of twitch height to 50% of control following administration of succinylcholine is a critical factor in avoiding life-threatening hemoglobin desaturation should difficulty in ventilation occur.1 Several investigators have demonstrated that a lower dose of succinylcholine (0.6 mg/kg) provides similar intubating conditions as a standard 1 mg/kg dose, while allowing more rapid recovery of spontaneous ventilation.2,3 However, morbidly obese patients have been excluded from these studies. The purpose of this study was to determine the ability of succinycholine 0.6 mg/kg to provide adequate intubating conditions for rapid sequence tracheal intubation in morbidly obese patients and to determine the recovery time to allow return of spontaneous ventilation.

Methods: Following IRB approval, informed consent was obtained from 15 patients with a body mass index (BMI) > 40 kg/m2 scheduled for elective surgical procedures with general endotracheal anesthesia. Patients were excluded if they were pregnant, had a known or suspected difficult airway, or a history of an abnormal response to succinylcholine. Drug doses were calculated using actual body weight. Anesthesia was induced using fentanyl 1-2mcg/kg and propofol 2.0-2.5 mg/kg. After loss of eyelash reflex and calibration of the accelomyography device (TOF-Watch SX, Organon-Teknika, Durham, NC), succinylcholine 0.6 mg/kg was administered into a freely flowing IV. Time to maximal twitch depression (no twitch) was recorded and then tracheal intubating conditions was graded by an experienced anesthesiologist using the Copenhagen Consensus Conference criteria.3 Following tracheal intubation, ventilation was assisted and anesthesia maintained with intermittent intravenous propofol doses and remifentanil infusion 0.1mcg/kg/min titrated to a BIS value < 50 (Aspect Medical, Newton, MA). Time to return of twitch height of at least 50% was recorded.

Results: Patients ranged in age from 29 years to 57 years (mean 42 years) with a BMI between 43 kg/m2 and 55 kg/m2 (mean 47 kg/m2). Mean time to maximal twitch suppression was 56 seconds + 22 seconds. Intubating conditions with maximal twitch suppression were graded as excellent in all cases using the Copenhagen criteria.3 Mean time to recovery of at least 50% twitch height was 244 seconds + 98 seconds.

References:

1.Benumof JL, Dagg, R, Benumof R: Critical hemoglobin desaturation will occur before return to an unparalyzed state following 1 mg/kg intravenous succinylcholine. Anesthesiology 1997; 87:979-82.

2.Kopman AF, Zhaku B, Lai KS: The "intubating dose" of succinylcholine: the effect of decreasing doses on recovery time. Anesthesiology 2003; 99:1050-4.

3.El-Orbany MI, Joseph NJ, Salem MR, Klowden AJ: The neuromuscular effects and tracheal intubation conditions after small doses of succinylcholine. Anesth Analg 2004; 98:1680-5.

Anesthesiology 2005; 103: A1170