Studies by F. Herbstreit and co-authors describe new findings in anesthesiology
2009 JUL 13 - (NewsRx.com) -- "Residual neuromuscular blockade increases the risk to develop postoperative complications. The authors hypothesized that minimal neuromuscular blockade (train-of-four [TOF] ratio 0.5-1) increases upper airway collapsibility and impairs upper airway dilator muscle compensatory responses to negative pharyngeal pressure challenges," investigators in Essen, Germany report. "Epiglottic and nasal mask pressures, genioglossus electromyogram, respiratory timing, and changes in lung volume were measured in awake healthy volunteers (n = 15) before, during (TOF = 0.5 and 0.8 [steady state]), and after recovery of TOF to unity from rocuronium-induced partial neuromuscular blockade. Passive upper airway closing pressure (negative pressure drops, random order, range +2 to -30 cm H2O) and pressure threshold for flow limitation were determined. Upper airway closing pressure increased (was less negative) significantly from baseline by 54 +/- 4.4% (means +/- SEM), 37 +/- 4.2%, and 16 +/- 41% at TOF ratios of 0.5, 0.8, and 1.0, respectively (P < 0.01 vs. baseline for any level). Phasic genioglossus activity almost quadrupled in response to negative (-20 cm H2O) pharyngeal pressure at baseline, and this increase was significantly impaired by 57 +/- 44% and 32 +/- 6% at TOF ratios of 0.5 and 0.8, respectively (P < 0.01 vs. baseline). End-expiratory lung volume, respiratory rate, and tidal volume did not change. Minimal neuromuscular blockade markedly increases upper airway closing pressure, partly fly impairing the genioglossus muscle compensatory response," wrote F. Herbstreit and colleagues. The researchers concluded: "Increased airway collapsibility despite unaffected values for testing ventilation may predispose patients to postoperative respiratory complications, particularly during airway challenges.." Herbstreit and colleagues published their study in Anesthesiology (Impaired Upper Airway Integrity by Residual Neuromuscular Blockade Increased Airway Collapsibility and Blunted Genioglossus Muscle Activity in Response to Negative Pharyngeal Pressure. Anesthesiology, 2009;110(6):1253-1260). For additional information, contact F. Herbstreit, Essen University Medical CenterKlin Anasthesiol & Intensive Medical, Hufelandstr 55, D-45122 Essen, Germany. The publisher of the journal Anesthesiology can be contacted at: Lippincott Williams & Wilkins, 530 Walnut St., Philadelphia, PA 19106-3621, USA. Keywords: Germany, Essen, Life Sciences, Postoperative Complications, Rocuronium, Neuromuscular Nondepolarizing Agent, Skeletal Muscle Relaxant, Anesthesiology. This article was prepared by Pain & Central Nervous System Week editors from staff and other reports. Copyright 2009, Pain & Central Nervous System Week via NewsRx.com.
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