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Anesthesia for the obese patient

Roman Schumann, MD
Section Editor
Stephanie B Jones, MD
Deputy Editor
Marianna Crowley, MD


As the prevalence of obesity increases worldwide, an increasing number of obese surgical patients will require anesthesia. Obesity is typically defined by body mass index (BMI), the ratio of weight (in kilograms) to the square of height (in meters) (calculator 1). In adults, the World Health Organization and the National Institute of Health define obesity as a BMI ≥30 kg/m2.

This topic reviews the changes in anatomy and physiology in obese patients that affect anesthetic management, anesthetic drug dosing in obesity, and planning the anesthetic (type of anesthesia, equipment, appropriate monitoring, and analgesic plan) as it differs from patients with normal BMI. Preoperative medical evaluation of obese patients, the impact of obstructive sleep apnea on anesthetic management, and general principles and techniques in anesthesia are discussed separately.

(See "Preanesthesia medical evaluation of the obese patient".)

(See "Surgical risk and the preoperative evaluation and management of adults with obstructive sleep apnea".)

(See "Intraoperative management of adults with obstructive sleep apnea".)


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Literature review current through: Aug 2017. | This topic last updated: Sep 11, 2017.
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  1. Ladosky W, Botelho MA, Albuquerque JP Jr. Chest mechanics in morbidly obese non-hypoventilated patients. Respir Med 2001; 95:281.
  2. Kabon B, Nagele A, Reddy D, et al. Obesity decreases perioperative tissue oxygenation. Anesthesiology 2004; 100:274.
  3. Littleton SW. Impact of obesity on respiratory function. Respirology 2012; 17:43.
  4. Jones RL, Nzekwu MM. The effects of body mass index on lung volumes. Chest 2006; 130:827.
  5. Adams JP, Murphy PG. Obesity in anaesthesia and intensive care. Br J Anaesth 2000; 85:91.
  6. Damia G, Mascheroni D, Croci M, Tarenzi L. Perioperative changes in functional residual capacity in morbidly obese patients. Br J Anaesth 1988; 60:574.
  7. Söderberg M, Thomson D, White T. Respiration, circulation and anaesthetic management in obesity. Investigation before and after jejunoileal bypass. Acta Anaesthesiol Scand 1977; 21:55.
  8. Lin CC, Wu KM, Chou CS, Liaw SF. Oral airway resistance during wakefulness in eucapnic and hypercapnic sleep apnea syndrome. Respir Physiol Neurobiol 2004; 139:215.
  9. Lee MY, Lin CC, Shen SY, et al. Work of breathing in eucapnic and hypercapnic sleep apnea syndrome. Respiration 2009; 77:146.
  10. Jense HG, Dubin SA, Silverstein PI, O'Leary-Escolas U. Effect of obesity on safe duration of apnea in anesthetized humans. Anesth Analg 1991; 72:89.
  11. Backman L, Freyschuss U, Hallberg D, Melcher A. Cardiovascular function in extreme obesity. Acta Med Scand 1973; 193:437.
  12. Alpert MA, Hashimi MW. Obesity and the heart. Am J Med Sci 1993; 306:117.
  13. Lavie CJ, Messerli FH. Cardiovascular adaptation to obesity and hypertension. Chest 1986; 90:275.
  14. Nakajima T, Fujioka S, Tokunaga K, et al. Noninvasive study of left ventricular performance in obese patients: influence of duration of obesity. Circulation 1985; 71:481.
  15. Schumann R, Jones SB, Ortiz VE, et al. Best practice recommendations for anesthetic perioperative care and pain management in weight loss surgery. Obes Res 2005; 13:254.
  16. Schumann R, Jones SB, Cooper B, et al. Update on best practice recommendations for anesthetic perioperative care and pain management in weight loss surgery, 2004-2007. Obesity (Silver Spring) 2009; 17:889.
  17. Hanley MJ, Abernethy DR, Greenblatt DJ. Effect of obesity on the pharmacokinetics of drugs in humans. Clin Pharmacokinet 2010; 49:71.
  18. De Baerdemaeker L, Margarson M. Best anaesthetic drug strategy for morbidly obese patients. Curr Opin Anaesthesiol 2016; 29:119.
  19. Blouin RA, Warren GW. Pharmacokinetic considerations in obesity. J Pharm Sci 1999; 88:1.
  20. Bluth T, Pelosi P, de Abreu MG. The obese patient undergoing nonbariatric surgery. Curr Opin Anaesthesiol 2016; 29:421.
  21. Hall JC, Tarala RA, Hall JL, Mander J. A multivariate analysis of the risk of pulmonary complications after laparotomy. Chest 1991; 99:923.
  22. Healy LA, Ryan AM, Gopinath B, et al. Impact of obesity on outcomes in the management of localized adenocarcinoma of the esophagus and esophagogastric junction. J Thorac Cardiovasc Surg 2007; 134:1284.
  23. Wigfield CH, Lindsey JD, Muñoz A, et al. Is extreme obesity a risk factor for cardiac surgery? An analysis of patients with a BMI > or = 40. Eur J Cardiothorac Surg 2006; 29:434.
  24. Nielsen KC, Guller U, Steele SM, et al. Influence of obesity on surgical regional anesthesia in the ambulatory setting: an analysis of 9,038 blocks. Anesthesiology 2005; 102:181.
  25. Schroeder K, Andrei AC, Furlong MJ, et al. The perioperative effect of increased body mass index on peripheral nerve blockade: an analysis of 528 ultrasound guided interscalene blocks. Rev Bras Anestesiol 2012; 62:28.
  26. Mariano ER, Brodsky JB. Comparison of procedural times for ultrasound-guided perineural catheter insertion in obese and nonobese patients. J Ultrasound Med 2011; 30:1357.
  27. Lam NC, Petersen TR, Gerstein NS, et al. A randomized clinical trial comparing the effectiveness of ultrasound guidance versus nerve stimulation for lateral popliteal-sciatic nerve blocks in obese patients. J Ultrasound Med 2014; 33:1057.
  28. Bomberg H, Albert N, Schmitt K, et al. Obesity in regional anesthesia--a risk factor for peripheral catheter-related infections. Acta Anaesthesiol Scand 2015; 59:1038.
  29. von Ungern-Sternberg BS, Regli A, Reber A, Schneider MC. Effect of obesity and thoracic epidural analgesia on perioperative spirometry. Br J Anaesth 2005; 94:121.
  30. Sharma M, Mehta Y, Sawhney R, et al. Thoracic epidural analgesia in obese patients with body mass index of more than 30 kg/m2 for off pump coronary artery bypass surgery. Ann Card Anaesth 2010; 13:28.
  31. Bamgbade OA, Khalaf WM, Ajai O, et al. Obstetric anaesthesia outcome in obese and non-obese parturients undergoing caesarean delivery: an observational study. Int J Obstet Anesth 2009; 18:221.
  32. Sprung J, Bourke DL, Grass J, et al. Predicting the difficult neuraxial block: a prospective study. Anesth Analg 1999; 89:384.
  33. de Filho GR, Gomes HP, da Fonseca MH, et al. Predictors of successful neuraxial block: a prospective study. Eur J Anaesthesiol 2002; 19:447.
  34. Schell K, Bradley E, Bucher L, et al. Clinical comparison of automatic, noninvasive measurements of blood pressure in the forearm and upper arm. Am J Crit Care 2005; 14:232.
  35. Li WY, Wang XH, Lu LC, Li H. Discrepancy of blood pressure between the brachial artery and radial artery. World J Emerg Med 2013; 4:294.
  36. Singer AJ, Kahn SR, Thode HC Jr, Hollander JE. Comparison of forearm and upper arm blood pressures. Prehosp Emerg Care 1999; 3:123.
  37. Pierin AM, Alavarce DC, Gusmão JL, et al. Blood pressure measurement in obese patients: comparison between upper arm and forearm measurements. Blood Press Monit 2004; 9:101.
  38. Domiano KL, Hinck SM, Savinske DL, Hope KL. Comparison of upper arm and forearm blood pressure. Clin Nurs Res 2008; 17:241.
  39. Anast N, Olejniczak M, Ingrande J, Brock-Utne J. The impact of blood pressure cuff location on the accuracy of noninvasive blood pressure measurements in obese patients: an observational study. Can J Anaesth 2016; 63:298.
  40. Hersh LT, Sesing JC, Luczyk WJ, et al. Validation of a conical cuff on the forearm for estimating radial artery blood pressure. Blood Press Monit 2014; 19:38.
  41. Chakravartty S, Sarma DR, Patel AG. Rhabdomyolysis in bariatric surgery: a systematic review. Obes Surg 2013; 23:1333.
  42. Vaughan RW, Wise L. Intraoperative arterial oxygenation in obese patients. Ann Surg 1976; 184:35.
  43. Pelosi P, Croci M, Calappi E, et al. Prone positioning improves pulmonary function in obese patients during general anesthesia. Anesth Analg 1996; 83:578.
  44. Palmon SC, Kirsch JR, Depper JA, Toung TJ. The effect of the prone position on pulmonary mechanics is frame-dependent. Anesth Analg 1998; 87:1175.
  45. Wu SD, Yilmaz M, Tamul PC, et al. Awake endotracheal intubation and prone patient self-positioning: anesthetic and positioning considerations during percutaneous nephrolithotomy in obese patients. J Endourol 2009; 23:1599.
  46. Douglass J, Fraser J, Andrzejowski J. Awake intubation and awake prone positioning of a morbidly obese patient for lumbar spine surgery. Anaesthesia 2014; 69:166.
  47. Isono S, Tanaka A, Nishino T. Lateral position decreases collapsibility of the passive pharynx in patients with obstructive sleep apnea. Anesthesiology 2002; 97:780.
  48. Ikeya E, Taguchi J, Ohta K, et al. Compartment syndrome of bilateral lower extremities following laparoscopic surgery of rectal cancer in lithotomy position: report of a case. Surg Today 2006; 36:1122.
  49. Mathews PV, Perry JJ, Murray PC. Compartment syndrome of the well leg as a result of the hemilithotomy position: a report of two cases and review of literature. J Orthop Trauma 2001; 15:580.
  50. http://www.apsf.org/newsletters/html/2013/spring/07_tabletipdanger.htm (Accessed on August 21, 2013).
  51. Schwemmer U, Papenfuss T, Greim C, et al. Ultrasound-guided interscalene brachial plexus anaesthesia: differences in success between patients of normal and excessive weight. Ultraschall Med 2006; 27:245.
  52. Regli A, von Ungern-Sternberg BS, Reber A, Schneider MC. Impact of spinal anaesthesia on peri-operative lung volumes in obese and morbidly obese female patients. Anaesthesia 2006; 61:215.
  53. Taivainen T, Tuominen M, Rosenberg PH. Influence of obesity on the spread of spinal analgesia after injection of plain 0.5% bupivacaine at the L3-4 or L4-5 interspace. Br J Anaesth 1990; 64:542.
  54. McCulloch WJ, Littlewood DG. Influence of obesity on spinal analgesia with isobaric 0.5% bupivacaine. Br J Anaesth 1986; 58:610.
  55. Hodgkinson R, Husain FJ. Obesity and the cephalad spread of analgesia following epidural administration of bupivacaine for Cesarean section. Anesth Analg 1980; 59:89.
  56. Qadeer MA, Rocio Lopez A, Dumot JA, Vargo JJ. Risk factors for hypoxemia during ambulatory gastrointestinal endoscopy in ASA I-II patients. Dig Dis Sci 2009; 54:1035.
  57. Chung F, Mezei G, Tong D. Pre-existing medical conditions as predictors of adverse events in day-case surgery. Br J Anaesth 1999; 83:262.
  58. American Society of Anesthesiologists Committee. Practice guidelines for preoperative fasting and the use of pharmacologic agents to reduce the risk of pulmonary aspiration: application to healthy patients undergoing elective procedures: an updated report by the American Society of Anesthesiologists Committee on Standards and Practice Parameters. Anesthesiology 2011; 114:495.
  59. Zalar A, Haddouche B, Antonietti M, et al. Lack of correlation between morbid obesity and severe gastroesophageal reflux disease in candidates for bariatric surgery: results of a large prospective study. Obes Surg 2013; 23:1939.
  60. Carron M, Veronese S, Gomiero W, et al. Hemodynamic and hormonal stress responses to endotracheal tube and ProSeal Laryngeal Mask Airway™ for laparoscopic gastric banding. Anesthesiology 2012; 117:309.
  61. Lundstrøm LH, Møller AM, Rosenstock C, et al. High body mass index is a weak predictor for difficult and failed tracheal intubation: a cohort study of 91,332 consecutive patients scheduled for direct laryngoscopy registered in the Danish Anesthesia Database. Anesthesiology 2009; 110:266.
  62. El-Orbany M, Woehlck HJ. Difficult mask ventilation. Anesth Analg 2009; 109:1870.
  63. Dixon BJ, Dixon JB, Carden JR, et al. Preoxygenation is more effective in the 25 degrees head-up position than in the supine position in severely obese patients: a randomized controlled study. Anesthesiology 2005; 102:1110.
  64. Altermatt FR, Muñoz HR, Delfino AE, Cortínez LI. Pre-oxygenation in the obese patient: effects of position on tolerance to apnoea. Br J Anaesth 2005; 95:706.
  65. Collins JS, Lemmens HJ, Brodsky JB, et al. Laryngoscopy and morbid obesity: a comparison of the "sniff" and "ramped" positions. Obes Surg 2004; 14:1171.
  66. El-Orbany M, Woehlck H, Salem MR. Head and neck position for direct laryngoscopy. Anesth Analg 2011; 113:103.
  67. Baraka AS, Taha SK, Aouad MT, et al. Preoxygenation: comparison of maximal breathing and tidal volume breathing techniques. Anesthesiology 1999; 91:612.
  68. Gagnon C, Fortier LP, Donati F. When a leak is unavoidable, preoxygenation is equally ineffective with vital capacity or tidal volume breathing. Can J Anaesth 2006; 53:86.
  69. Gambee AM, Hertzka RE, Fisher DM. Preoxygenation techniques: comparison of three minutes and four breaths. Anesth Analg 1987; 66:468.
  70. Carron M, Zarantonello F, Tellaroli P, Ori C. Perioperative noninvasive ventilation in obese patients: a qualitative review and meta-analysis. Surg Obes Relat Dis 2016; 12:681.
  71. Gander S, Frascarolo P, Suter M, et al. Positive end-expiratory pressure during induction of general anesthesia increases duration of nonhypoxic apnea in morbidly obese patients. Anesth Analg 2005; 100:580.
  72. Delay JM, Sebbane M, Jung B, et al. The effectiveness of noninvasive positive pressure ventilation to enhance preoxygenation in morbidly obese patients: a randomized controlled study. Anesth Analg 2008; 107:1707.
  73. Futier E, Constantin JM, Pelosi P, et al. Noninvasive ventilation and alveolar recruitment maneuver improve respiratory function during and after intubation of morbidly obese patients: a randomized controlled study. Anesthesiology 2011; 114:1354.
  74. Weingart SD, Levitan RM. Preoxygenation and prevention of desaturation during emergency airway management. Ann Emerg Med 2012; 59:165.
  75. Ramachandran SK, Cosnowski A, Shanks A, Turner CR. Apneic oxygenation during prolonged laryngoscopy in obese patients: a randomized, controlled trial of nasal oxygen administration. J Clin Anesth 2010; 22:164.
  76. Taha SK, Siddik-Sayyid SM, El-Khatib MF, et al. Nasopharyngeal oxygen insufflation following pre-oxygenation using the four deep breath technique. Anaesthesia 2006; 61:427.
  77. Sakles JC, Mosier JM, Patanwala AE, et al. First Pass Success Without Hypoxemia Is Increased With the Use of Apneic Oxygenation During Rapid Sequence Intubation in the Emergency Department. Acad Emerg Med 2016; 23:703.
  78. Rothen HU, Sporre B, Engberg G, et al. Prevention of atelectasis during general anaesthesia. Lancet 1995; 345:1387.
  79. Edmark L, Kostova-Aherdan K, Enlund M, Hedenstierna G. Optimal oxygen concentration during induction of general anesthesia. Anesthesiology 2003; 98:28.
  80. Hedenstierna G, Rothen HU. Respiratory function during anesthesia: effects on gas exchange. Compr Physiol 2012; 2:69.
  81. Strum EM, Szenohradszki J, Kaufman WA, et al. Emergence and recovery characteristics of desflurane versus sevoflurane in morbidly obese adult surgical patients: a prospective, randomized study. Anesth Analg 2004; 99:1848.
  82. Juvin P, Vadam C, Malek L, et al. Postoperative recovery after desflurane, propofol, or isoflurane anesthesia among morbidly obese patients: a prospective, randomized study. Anesth Analg 2000; 91:714.
  83. Bilotta F, Doronzio A, Cuzzone V, et al. Early postoperative cognitive recovery and gas exchange patterns after balanced anesthesia with sevoflurane or desflurane in overweight and obese patients undergoing craniotomy: a prospective randomized trial. J Neurosurg Anesthesiol 2009; 21:207.
  84. Leykin Y, Pellis T, Del Mestro E, et al. Anesthetic management of morbidly obese and super-morbidly obese patients undergoing bariatric operations: hospital course and outcomes. Obes Surg 2006; 16:1563.
  85. De Baerdemaeker LE, Jacobs S, Den Blauwen NM, et al. Postoperative results after desflurane or sevoflurane combined with remifentanil in morbidly obese patients. Obes Surg 2006; 16:728.
  86. Arain SR, Barth CD, Shankar H, Ebert TJ. Choice of volatile anesthetic for the morbidly obese patient: sevoflurane or desflurane. J Clin Anesth 2005; 17:413.
  87. Vallejo MC, Sah N, Phelps AL, et al. Desflurane versus sevoflurane for laparoscopic gastroplasty in morbidly obese patients. J Clin Anesth 2007; 19:3.
  88. Zeidan A, Mazoit JX. Minimal alveolar concentration of sevoflurane for maintaining bispectral index below 50 in morbidly obese patients. Acta Anaesthesiol Scand 2013; 57:474.
  89. Matsuura T, Oda Y, Tanaka K, et al. Advance of age decreases the minimum alveolar concentrations of isoflurane and sevoflurane for maintaining bispectral index below 50. Br J Anaesth 2009; 102:331.
  90. Brodsky JB, Lemmens HJ, Collins JS, et al. Nitrous oxide and laparoscopic bariatric surgery. Obes Surg 2005; 15:494.
  91. Schumann R. Pulmonary physiology of the morbidly obese and the effects of anesthesia. Int Anesthesiol Clin 2013; 51:41.
  92. Pelosi P, Brusasco C, Reinius h. Is protective lung ventilation safe in morbidly obese patients?. In: Controversies in the Management of the Obese Surgical Patinet, Leykin Y, Brodsky JB (Eds), Springer-Verlag Italia, Milan, Heidelberg, New York, Dordrecht, London 2013. p.179.
  93. Futier E, Constantin JM, Paugam-Burtz C, et al. A trial of intraoperative low-tidal-volume ventilation in abdominal surgery. N Engl J Med 2013; 369:428.
  94. Aldenkortt M, Lysakowski C, Elia N, et al. Ventilation strategies in obese patients undergoing surgery: a quantitative systematic review and meta-analysis. Br J Anaesth 2012; 109:493.
  95. Erlandsson K, Odenstedt H, Lundin S, Stenqvist O. Positive end-expiratory pressure optimization using electric impedance tomography in morbidly obese patients during laparoscopic gastric bypass surgery. Acta Anaesthesiol Scand 2006; 50:833.
  96. Talab HF, Zabani IA, Abdelrahman HS, et al. Intraoperative ventilatory strategies for prevention of pulmonary atelectasis in obese patients undergoing laparoscopic bariatric surgery. Anesth Analg 2009; 109:1511.
  97. Whalen FX, Gajic O, Thompson GB, et al. The effects of the alveolar recruitment maneuver and positive end-expiratory pressure on arterial oxygenation during laparoscopic bariatric surgery. Anesth Analg 2006; 102:298.
  98. Bohm SH, Thamm OC, von Sandersleben A, et al. Alveolar recruitment strategy and high positive end-expiratory pressure levels do not affect hemodynamics in morbidly obese intravascular volume-loaded patients. Anesth Analg 2009; 109:160.
  99. Jain AK, Dutta A. Stroke volume variation as a guide to fluid administration in morbidly obese patients undergoing laparoscopic bariatric surgery. Obes Surg 2010; 20:709.
  100. Gaszynski T, Szewczyk T, Gaszynski W. Randomized comparison of sugammadex and neostigmine for reversal of rocuronium-induced muscle relaxation in morbidly obese undergoing general anaesthesia. Br J Anaesth 2012; 108:236.
  101. Carron M, Parotto E, Ori C. Prolonged neuromuscular block associated to non-alcoholic steatohepatitis in morbidly obese patient: neostigmine versus sugammadex. Minerva Anestesiol 2012; 78:112.
  102. Carron M, Freo U, Ori C. Sugammadex for treatment of postoperative residual curarization in a morbidly obese patient. Can J Anaesth 2012; 59:813.
  103. Van Lancker P, Dillemans B, Bogaert T, et al. Ideal versus corrected body weight for dosage of sugammadex in morbidly obese patients. Anaesthesia 2011; 66:721.
  104. Budiansky AS, Margarson MP, Eipe N. Acute pain management in morbid obesity - an evidence based clinical update. Surg Obes Relat Dis 2017; 13:523.
  105. Govindarajan R, Ghosh B, Sathyamoorthy MK, et al. Efficacy of ketorolac in lieu of narcotics in the operative management of laparoscopic surgery for morbid obesity. Surg Obes Relat Dis 2005; 1:530.
  106. Kamelgard JI, Kim KA, Atlas G. Combined preemptive and preventive analgesia in morbidly obese patients undergoing open gastric bypass: A pilot study. Surg Obes Relat Dis 2005; 1:12.
  107. Schumann R, Shikora S, Weiss JM, et al. A comparison of multimodal perioperative analgesia to epidural pain management after gastric bypass surgery. Anesth Analg 2003; 96:469.
  108. McNicol ED, Tzortzopoulou A, Cepeda MS, et al. Single-dose intravenous paracetamol or propacetamol for prevention or treatment of postoperative pain: a systematic review and meta-analysis. Br J Anaesth 2011; 106:764.
  109. Apfel CC, Turan A, Souza K, et al. Intravenous acetaminophen reduces postoperative nausea and vomiting: a systematic review and meta-analysis. Pain 2013; 154:677.
  110. Feld JM, Laurito CE, Beckerman M, et al. Non-opioid analgesia improves pain relief and decreases sedation after gastric bypass surgery. Can J Anaesth 2003; 50:336.
  111. Sollazzi L, Modesti C, Vitale F, et al. Preinductive use of clonidine and ketamine improves recovery and reduces postoperative pain after bariatric surgery. Surg Obes Relat Dis 2009; 5:67.
  112. Pawlik MT, Hansen E, Waldhauser D, et al. Clonidine premedication in patients with sleep apnea syndrome: a randomized, double-blind, placebo-controlled study. Anesth Analg 2005; 101:1374.
  113. Feld JM, Hoffman WE, Stechert MM, et al. Fentanyl or dexmedetomidine combined with desflurane for bariatric surgery. J Clin Anesth 2006; 18:24.
  114. Tufanogullari B, White PF, Peixoto MP, et al. Dexmedetomidine infusion during laparoscopic bariatric surgery: the effect on recovery outcome variables. Anesth Analg 2008; 106:1741.
  115. Bakhamees HS, El-Halafawy YM, El-Kerdawy HM, et al. Effects of dexmedetomidine in morbidly obese patients undergoing laparoscopic gastric bypass. Middle East J Anaesthesiol 2007; 19:537.
  116. De Oliveira GS Jr, Duncan K, Fitzgerald P, et al. Systemic lidocaine to improve quality of recovery after laparoscopic bariatric surgery: a randomized double-blinded placebo-controlled trial. Obes Surg 2014; 24:212.
  117. Cabrera Schulmeyer MC, de la Maza J, Ovalle C, et al. Analgesic effects of a single preoperative dose of pregabalin after laparoscopic sleeve gastrectomy. Obes Surg 2010; 20:1678.
  118. Alimian M, Imani F, Faiz SH, et al. Effect of oral pregabalin premedication on post-operative pain in laparoscopic gastric bypass surgery. Anesth Pain Med 2012; 2:12.
  119. Hassani V, Pazouki A, Nikoubakht N, et al. The effect of gabapentin on reducing pain after laparoscopic gastric bypass surgery in patients with morbid obesity: a randomized clinical trial. Anesth Pain Med 2015; 5:e22372.
  120. Thomas JA, McIntosh JM. Are incentive spirometry, intermittent positive pressure breathing, and deep breathing exercises effective in the prevention of postoperative pulmonary complications after upper abdominal surgery? A systematic overview and meta-analysis. Phys Ther 1994; 74:3.
  121. Squadrone V, Coha M, Cerutti E, et al. Continuous positive airway pressure for treatment of postoperative hypoxemia: a randomized controlled trial. JAMA 2005; 293:589.
  122. Neligan PJ, Malhotra G, Fraser M, et al. Noninvasive ventilation immediately after extubation improves lung function in morbidly obese patients with obstructive sleep apnea undergoing laparoscopic bariatric surgery. Anesth Analg 2010; 110:1360.
  123. Battisti A, Michotte JB, Tassaux D, et al. Non-invasive ventilation in the recovery room for postoperative respiratory failure: a feasibility study. Swiss Med Wkly 2005; 135:339.
  124. Huerta S, DeShields S, Shpiner R, et al. Safety and efficacy of postoperative continuous positive airway pressure to prevent pulmonary complications after Roux-en-Y gastric bypass. J Gastrointest Surg 2002; 6:354.
  125. Ramirez A, Lalor PF, Szomstein S, Rosenthal RJ. Continuous positive airway pressure in immediate postoperative period after laparoscopic Roux-en-Y gastric bypass: is it safe? Surg Obes Relat Dis 2009; 5:544.
  126. Tong S, Gower J, Morgan A, et al. Noninvasive positive pressure ventilation in the immediate post-bariatric surgery care of patients with obstructive sleep apnea: a systematic review. Surg Obes Relat Dis 2017; 13:1227.
  127. www.asahq.org (Accessed on December 08, 2010).
  128. Gross JB, Bachenberg KL, Benumof JL, et al. Practice guidelines for the perioperative management of patients with obstructive sleep apnea: a report by the American Society of Anesthesiologists Task Force on Perioperative Management of patients with obstructive sleep apnea. Anesthesiology 2006; 104:1081.
  129. Joshi GP, Ankichetty SP, Gan TJ, Chung F. Society for Ambulatory Anesthesia consensus statement on preoperative selection of adult patients with obstructive sleep apnea scheduled for ambulatory surgery. Anesth Analg 2012; 115:1060.