Br. J. Anaesth.-2010-McKay-175-82

Effect of increased body mass index and anaesthetic duration on recovery of protective airway reflexes after sevoflurane vs desflurane † R. E. McKay 1 * ‡ , A. Malhotra 1 , O. S. Cakmakkaya 1 2 , K. T. Hall 1 , W. R. McKay 1 and C. C. Apfel 1 1 Department of Anaesthesia and Perioperative Care, C-450, University of California San Francisco, San Francisco, CA 94143-0648, USA. 2 Cerrahpasa Medical School, University of Istanbul, Istanbul, Turkey *Corresponding author. E-mail: [email protected] Background. Increased BMI may increase the body’s capacity to store potent inhaled anaesthetics, more so with more soluble agents. Accordingly, we asked whether increased BMI and longer anaesthesia prolonged airway reflex recovery. Methods. W e me asur ed time fr om anaes the tic disc ont inuat ion unt il firs t re spo nse to command (T1); from response to command until ability to swallow (T2); and from anaesthetic discontinuation to recovery of ability to swallow (T3) in 120 patients within three BMI ranges (18–24, 25–29, and !30 kg m 22 ). All rec eive d sev oflurane or desflurane, deliv ere d via an LMA. Results. T1 and T3 after sevoflurane exceeded T1 and T3 after desflurane: 6.6 ( SD 4.2) vs 4.0 (1.9) min (P ,0.001), and 14.1 ( SD 8.3) vs 6.1 (2.0) min ( P ,0.0001). T3 correlated more strongly wi th BMI af te r sevoflurane (28 s pe r kg m 22 , P ¼0. 02) than desflur ane (7 s per kg m 22 , P ¼0.03). Regarding T2, patients receiving sevoflurane with BMI !30 kg m 22 were less often able to swallow 2 min after response to command than were those with BMI 18–24 or 25–29 kg m 22 (3/20 vs 10/20 or 9/20, P ,0.05). Each sevoflurane MAC-hour delayed T3 by 4.5 min (268 s) (R¼0.46, P ,0.001) whereas each desflurane MAC-hour delayed T3 by 0.2 min (16 s) (R¼0.10, P ¼0.44). Conclusions. Prolonged sevoflurane administration and greater BMI delay airway reflex recovery . The contr ibut ion of BMI to thi s del a y is more pr ono unc ed af te r sev oflu rane tha n desflurane. Br J Anaesth 2010; 104: 175–82 Keywords: airway, reflexes; anaesthetics, desflurane; anaesthetics, sevoflurane; anaesthetics, volatile; pharmacokinetics, obesity; pharmacokinetics, uptake Accepted for publication: November 27, 2009 Volunteers 1 and patients 2 – 4 awaken more rapidly after des- flura ne than sev oflurane anaest he si a, in part at le ast because of the lesser solubility of desflurane. Does a more rapid awa keni ng tran slate into grea ter pati ent safet y, par- ti cula rl y into a fa st er re cove ry of pr ot ecti ve ai rway reflexes? At 25% of MACawake, sevo flura ne, isoflu rane , and propo fol signifi cantly dec re ase the coordi na tion of pharyngeal muscles, 5 and patients anaesthetized with desflurane recover protective airway reflexes faster than those anaesthetized with sevoflurane. 6 † Interi m findings from thi s tri al were pr ese nted as a pos ter at the 2008 Eur ope an Soc iet y of Anae st hes ia in Copenhage n, Denmar k. European Journal of Anaesthesiology 2008; 25 (Suppl 44): 2AP2–7. ‡ Declaration of interest. R.E.M. has received research support in the past from Baxter Healthcar e for other studies, but did not rece ive support for this study. She has also received honoraria for speaking fr om Baxter Hea lth car e. Baxter manufa ctures sev oflur ane and desflurane. R.E.M. is a member of the Speakers Bureau for Baxter Healthcare, manufacturer of sevoflurane and desflurane. In addition, Baxter Healthcare has provided research support to the University of California for some of R.E.M.’s investigator-initiated projects in the past. # The Author [2009]. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: [email protected] British Journal of Anaesthesia 104 (2): 175–82 (2010) doi:10.1093 /bja/aep374 Advance Ac cess public ation December 26 , 2009 b y g u e s t o F e b r u a r y 5 , 2 0 1 2 h t t p : / / b j a . o x f o r d j o u r n a l s . o r g / D o w n l o a d e d f r o m

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Br. J. Anaesth.-2010-McKay-175-82