Topical lidocaine reduces the risk of perioperative airway complications in children with upper respiratory tract infections.

PURPOSE: To determine the effect of topically applied lidocaine on perioperative airway complications when using a laryngeal mask airway device (LMAD) in children either with or without a history of recent or ongoing upper respiratory tract infection (URI). METHODS: In a randomized controlled double-blind trial, 34 children with a history of recent or ongoing URI and 32 non-URI children- all of whom were younger than age ten and scheduled to undergo minor surgical procedures-were randomly assigned to either a lidocaine or a placebo group. In the lidocaine group, an LMAD was lubricated with lidocaine gel before insertion, and a clear lubricating gel was used in the placebo group. The following data were recorded after standardized anesthesia induction and airway management: postoperative complications, such as coughing, desaturation, laryngospasm, and increased oral secretions, as well as length of stay in the postanesthetic recovery unit. RESULTS: Children with URI had a lower overall perioperative complication rate if they received a lidocaine gel (35%) rather than placebo (94%) (P < 0.01). Also, the incidence of postoperative coughing was less (12% vs 53%; P = 0.03). In non-URI patients, lidocaine did not significantly reduce the rate of airway complications compared with placebo (17% vs 24%, respectively). CONCLUSION: Lubrication of the LMAD with lidocaine gel reduces the incidence of airway complications in children with an upper respiratory tract infection.

Resistive polymer versus forced-air warming: comparable heat transfer and core rewarming rates in volunteers.

BACKGROUND: Mild perioperative hypothermia increases the risk of several severe complications. Perioperative patient warming to preserve normothermia has thus become routine, with forced-air warming being used most often. In previous studies, various resistive warming systems have shown mixed results in comparison with forced-air. Recently, a polymer-based resistive patient warming system has been developed. We compared the efficacy of a standard forced-air warming system with the resistive polymer system in volunteers. METHODS: Eight healthy volunteers participated, each on two separate study days. Unanesthetized volunteers were cooled to a core temperature (tympanic membrane) of 34 degrees C by application of forced-air at 10 degrees C and a circulating-water mattress at 4 degrees C. Meperidine and buspirone were administered to prevent shivering. In a randomly designated order, volunteers were then rewarmed (until their core temperatures reached 36 degrees C) with one of the following active warming systems: (1) forced-air warming (Bair Hugger warming cover #300, blower #750, Arizant, Eden Prairie, MN); or (2) polymer fiber resistive warming (HotDog whole body blanket, HotDog standard controller, Augustine Biomedical, Eden Prairie, MN). The alternate system was used on the second study day. Metabolic heat production, cutaneous heat loss, and core temperature were measured. RESULTS: Metabolic heat production and cutaneous heat loss were similar with each system. After a 30-min delay, core temperature increased nearly linearly by 0.98 (95% confidence interval 0.91-1.04) degrees C/h with forced-air and by 0.92 (0.85-1.00) degrees C/h with resistive heating (P = 0.4). CONCLUSIONS: Heating efficacy and core rewarming rates were similar with full-body forced-air and full-body resistive polymer heating in healthy volunteers.

Lower flange modification improves performance of the Macintosh, but not the Miller laryngoscope blade.

PURPOSE: In order to minimize the potential for dental damage and to improve laryngeal visualization during tracheal intubation, two commonly used laryngoscope blades were modified and compared in a clinical setting: the Miller laryngoscope blade and the Macintosh laryngoscope blade. Modified versions of both laryngoscope blades with a lowered heel (Callander modification) at the proximal end of the blade were compared to standard blades. METHODS: Forty patients scheduled for general anesthesia requiring endotracheal intubation were studied prospectively. Preoperatively, the patients' airways were evaluated according to Mallampati score, thyromental distance and interincisor gap. After induction of anesthesia laryngoscopy was performed with the original laryngoscope and its modified counterpart in random order. A lateral x-ray of the neck was taken after the optimal view had been obtained, and blade-tooth distance, laryngeal view, blade-tooth contact and need for assistance were measured. Using angular calculations the laryngoscopes were analyzed at different insertion depths on graph paper, and the results were compared with data from the lateral x-rays. RESULTS: With a modified Macintosh blade the blade-tooth distance was significantly greater in comparison to the original design (2.5 +/- 2.1 cm vs 0.2 +/- 0.1 cm, P < 0.01). Consequently the number of blade-tooth contacts was significantly lower (20% vs 75%, P < 0.05). The best laryngeal view could be obtained using a modified Macintosh laryngoscope. With a modified Miller laryngoscope laryngeal visibility was not improved and assistance was required more often to achieve adequate intubating conditions (35% vs 5%, P < 0.05). CONCLUSION: A reduction of the proximal flange of a Miller blade decreases the blade's effectiveness for laryngeal visualization, whereas a similar modification of a Macintosh blade increases blade-tooth distance, decreases the number of blade-tooth contacts and provides a better laryngeal view.