Comparison of the Anesthetic Requirement for Tolerance of Laryngeal Mask Airway and Endotracheal Tube Christopher J. Wilkins, MB, Wendell c. Stevens, MD
ChB,
Paul G.
w.Cramp, MB, ChB, James Staples, MD, and
Department of Anesthesiology, Oregon Health Sciences University, Portland, Oregon
We tested the hypothesis that the laryngeal mask airway (LMA) is tolerated at lighter levels of anesthesia than an endotracheal tube (ET). We studied 20 unpremedicated, nonsmoking ASA physical status I or II patients aged 18-40 yr whose surgery lasted >1 h. Subjects were randomly assigned to receive either an ET or LMA. Anesthesia was induced with intravenous propofol and the LMA or ET was inserted. The ETgroup patients received 1.5 mgkg of succinylcholine, preceded by vecuronium (0.015 mg/kg IV). Maintenance of anesthesia was with only isoflurane and approximately 66% N,O in 0, by spontaneous ventilation. All gas concentrations were measured by a Raman spectrometer sampling from the breathing
A
major responsibility of the anesthesiologist in caring for the anesthetized patient is ensuring patency of the airway and adequacy of ventilation. Problems may occur during light anesthesia (coughing, breath holding, and airway obstruction from soft tissues, laryngeal spasm, and bronchospasm); during deep anesthesia (hypercarbia and hypoxia from respiratory depression); or at any level of anesthesia (all of the above plus inability to intubate the trachea and the presence of foreign material in the respiratory tract). These problems may be overcome in a number of different ways. A novel approach to avoid, or better manage, some of them is the use of the laryngeal mask airway (LMA) developed by Brain (1,2). The LMA (Intavent International, The Netherlands) is inserted blindly through the mouth and forms an airtight seal against the perimeter of the larynx after inflation of the elliptical cuff within the hypopharynx (1,2). One of its specific advantages is its capacity to provide a clear airway in patients in whom convenAccepted for publication July 2, 1992. Address correspondence to Mr. Wilkins, Department of Anesthesiology, UHS-2, Oregon Health Sciences University, 3181 S.W. Sam Jackson Park Road, Portland, OR 97201-3098. Reprints will not be available.
794
Anesth Analg 1992;75:794-7
circuit end of the LMA or ET. Toward the end of the procedure, the end-tidal N,O and isoflurane concentrations were allowed to decrease to
ChB,
Paul G.
w.Cramp, MB, ChB, James Staples, MD, and
Department of Anesthesiology, Oregon Health Sciences University, Portland, Oregon
We tested the hypothesis that the laryngeal mask airway (LMA) is tolerated at lighter levels of anesthesia than an endotracheal tube (ET). We studied 20 unpremedicated, nonsmoking ASA physical status I or II patients aged 18-40 yr whose surgery lasted >1 h. Subjects were randomly assigned to receive either an ET or LMA. Anesthesia was induced with intravenous propofol and the LMA or ET was inserted. The ETgroup patients received 1.5 mgkg of succinylcholine, preceded by vecuronium (0.015 mg/kg IV). Maintenance of anesthesia was with only isoflurane and approximately 66% N,O in 0, by spontaneous ventilation. All gas concentrations were measured by a Raman spectrometer sampling from the breathing
A
major responsibility of the anesthesiologist in caring for the anesthetized patient is ensuring patency of the airway and adequacy of ventilation. Problems may occur during light anesthesia (coughing, breath holding, and airway obstruction from soft tissues, laryngeal spasm, and bronchospasm); during deep anesthesia (hypercarbia and hypoxia from respiratory depression); or at any level of anesthesia (all of the above plus inability to intubate the trachea and the presence of foreign material in the respiratory tract). These problems may be overcome in a number of different ways. A novel approach to avoid, or better manage, some of them is the use of the laryngeal mask airway (LMA) developed by Brain (1,2). The LMA (Intavent International, The Netherlands) is inserted blindly through the mouth and forms an airtight seal against the perimeter of the larynx after inflation of the elliptical cuff within the hypopharynx (1,2). One of its specific advantages is its capacity to provide a clear airway in patients in whom convenAccepted for publication July 2, 1992. Address correspondence to Mr. Wilkins, Department of Anesthesiology, UHS-2, Oregon Health Sciences University, 3181 S.W. Sam Jackson Park Road, Portland, OR 97201-3098. Reprints will not be available.
794
Anesth Analg 1992;75:794-7
circuit end of the LMA or ET. Toward the end of the procedure, the end-tidal N,O and isoflurane concentrations were allowed to decrease to
