Contributors:

Adult section: Nabil Elkassabany, Stavros Memtsoudis, Tajender Vasu, Susana Vacas, Frances Chung

Pediatric section: Kimmo Murto

Noninvasive ventilation in mild obesity hypoventilation syndrome: a randomized controlled trial.  Borel JC, Tamisier R, Gonzalez-Bermejo J, Baguet JP, Monneret D, Arnol N, Roux-Lombard P, Wuyam B, Levy P, Pépin JL. Chest 2012; 141(3): 692–702.
http://www.ncbi.nlm.nih.gov/pubmed/21885724

In this RCT, the authors evaluated the impact of one month NIV (Non-Invasive Ventilation) on mild OHS (Obesity Hypoventilation Syndrome) compared with lifestyle change. NIV treatment significantly reduced daytime PaCO2  and apnea-hypopnea index. However, the use of NIV did not lead to significant improvement in daytime sleepiness, or inflammatory, cytokine, or metabolic markers.

 

Obstructive sleep apnea syndrome and perioperative complications: a systematic review of the literature.  Vasu TS, Grewal R, Doghramji K.  J Clin Sleep Med 2012; 8(2): 199–207.
http://www.ncbi.nlm.nih.gov/pubmed/22505868

In this systematic review, the authors describe the epidemiology and pathophysiology of an association between OSAS and perioperative complications.  They also discuss the perioperative strategy to identify and manage these patients.

 

Respiratory event detection by a positive airway pressure device.  Berry RB, Kushida CA, Kryger MH, Soto-Calderon H, Staley B, Kuna ST.  Sleep 2012; 35(3): 361–7.
http://www.ncbi.nlm.nih.gov/pubmed/22379242

The purpose of this study was to compare the AED (Automatic Event Detection) algorithm used in PAP device with manually scored events on PSG. The AHI, AI, and HI by the two methods were highly correlated. An AHI < 10 events/hr by AED is likely to indicate efficacious treatment. However, high AHI values by AED may represent inadequate treatment especially if the reported events are apneas.

 

Clinical predictors of apnoea-hypopnoea during propofol sedation in patients undergoing spinal anaesthesia.  Kim GH, Lee JJ, Choi SJ, Shin BS, Lee AR, Lee SH, Kim MH. Anaesthesia. 2012 Apr 16.
http://www.ncbi.nlm.nih.gov/pubmed/22506571 

This study assessed the relationship between the occurrence of apnoea-hypopnoea during propofol sedation for spinal anaesthesia and two different predictive tests of sleep apnoea: the STOP-Bang score and the OSA score. Both assessment tools have some predictive value for the occurrence of apnoea-hypopnoea during propofol sedation in patients undergoing spinal anaesthesia.

 

High STOP-Bang score indicates a high probability of obstructive sleep apnoea. Chung F, Subramanyam R, Liao P, Sasaki E, Shapiro C, Sun Y. Br J Anaesth. 2012 May;108(5):768–75. Epub 2012 Mar 8.
http://www.ncbi.nlm.nih.gov/pubmed/22401881

The STOP-Bang questionnaire is used to screen patients for OSA. This study evaluated the association between STOP-Bang scores and the probability of OSA. In the surgical population, a STOP-Bang score of 5–8 identified patients with high probability of moderate/severe OSA. The STOP-Bang score can help the healthcare team to stratify patients for unrecognized OSA, practice perioperative precautions, or triage patients for diagnosis and treatment.

 

Review of interscalene block for postoperative analgesia after shoulder surgery in obese patients.  Al-Nasser B. Acta Anaesthesiol Taiwan. 2012 Mar;50(1):29–34. Epub 2012 Mar 25.
http://www.ncbi.nlm.nih.gov/pubmed/22500911

The ongoing debate on the relevance of obesity, for example in terms of OSA syndrome, obesity hypoventilation syndrome, and other related respiratory disturbances, in relation to the choice of analgesic techniques, especially interscalene block, patient-controlled intravenous analgesia and patient monitoring, demands large-scale, well-designed studies to resolve it. Nevertheless, obesity per se should not dissuade patients from undergoing shoulder surgery under interscalene block.

 

Obesity and obstructive sleep apnoea: mechanisms for increased collapsibility of the passive pharyngeal airway. Isono S.  Respirology. 2012 Jan;17(1):32–42.
http://www.ncbi.nlm.nih.gov/pubmed/22023094

In the pharyngeal airway region, excessive soft tissue for a given maxillomandibular enclosure size (upper airway anatomical imbalance) can increase tissue pressure surrounding the pharyngeal airway, thereby narrowing the airway. Lung volume reduction due to excessive central fat deposition may decrease longitudinal tracheal traction forces and pharyngeal wall tension, changing the ‘tube law’ in the pharyngeal airway (lung volume dependence of the upper airway). The lung volume dependence of pharyngeal airway patency appears to contribute more significantly to the development of OSA in morbidly obese, apnoeic patients.

 

Risk for Hospital Readmission following Bariatric Surgery.  Dorman RB, Miller CJ, Leslie DB, Serrot FJ, Slusarek B, Buchwald H, Connett JE, Ikramuddin S.  PLoS One. 2012;7(3):e32506. Epub 2012.
http://www.ncbi.nlm.nih.gov/pubmed/22412881

This is a prospective observational study of 24,662 patients undergoing primary RYGB and 26,002 patients undergoing primary AGB at 249 and 317 Bariatric Surgery Centers of Excellence, for three years. The readmission rate was 5.8% for RYGB and 1.2% for AGB patients 30 days after discharge. Readmission rates are low and mortality is very rare following bariatric surgery, but risk for both is significantly higher after RYGB. Predictors of readmission were disparate for the two procedures. Results do not support excluding patients with certain comorbidities since any reductions in overall readmission rates would be very small on the absolute risk scale.

 

Canadian Thoracic Society 2011 guideline update: diagnosis and treatment of sleep disordered breathing.  Fleetham J, Ayas N, Bradley D, Fitzpatrick M, Oliver TK, Morrison D, Ryan F, Series F, Skomro R, Tsai W; Canadian Thoracic Society Sleep Disordered Breathing Committee. Can Respir J 2011; Jan-Feb;18(1):25–47.
http://www.ncbi.nlm.nih.gov/pubmed/21369547

The CTS Sleep Disordered Breathing Committee posed specific questions for 8 areas. The recommendations regarding maximum assessment wait times, portable monitoring, treatment of asymptomatic adult OSA patients, treatment with conventional CPAP compared with automatic CPAP, and treatment of central sleep apnea syndrome in heart failure patients replace the recommendations in the 2006⁄2007 guidelines. The recommendations on bariatric surgery, complex sleep apnea and optimum positive airway pressure technologies are new topics, which were not covered in the 2006⁄2007 guidelines.

 

Continuous positive airway pressure in severe obstructive sleep apnea reduces pain sensitivity.  Khalid I, Roehrs TA, Hudgel DW, Roth T.  Sleep 2011; 34(12):1687–91.
http://www.ncbi.nlm.nih.gov/pubmed/22131606

This study is to evaluate effects of CPAP on pain sensitivity in severe OSA patients. Apnea-hypopnea index (AHI) decreased from 50.9 ± 14.5 to 1.4 ± 1.0 with CPAP, and sleep continuity improved. CPAP treatment reduces pain sensitivity in OSA patients.

 

More Codeine Fatalities After Tonsillectomy in North American Children.  Kelly LE, Rieder M, van den Anker J, Malkin B, Ross C, Neely MN, Carleton B, Hayden MR, Madadi P, Koren G.  Pediatrics. 2012 Apr 9. [Epub ahead of print].
http://www.ncbi.nlm.nih.gov/pubmed/22492761

In 2009 the fatal case of a toddler who had received codeine after adenotonsillectomy for OSA syndrome was first reported. The child was an ultra-rapid metabolizer of cytochrome P4502D6 (CYP2D6). Three additional fatal or life-threatening cases are now reported. In the 2 fatal cases, functional gene duplications encoding for CYP2D6 caused a significantly greater production of potent morphine from its parent drug, codeine. A severe case of respiratory depression in an extensive metabolizer is also noted. These cases demonstrate that analgesia with codeine or other opioids that use the CYP2D6 pathway after adenotonsillectomy may not be safe in young children with OSA syndrome.

 

Supraglottoplasty for occult laryngomalacia to improve obstructive sleep apnea syndrome.  Chan DK, Truong MT, Koltai PJ. Arch Otolaryngol Head Neck Surg. 2012;138(1):50–4.
http://www.ncbi.nlm.nih.gov/pubmed/22249629

Supraglottoplasty for occult laryngomalacia resulted in statistically significant reduction in the apnea-hypopnea index. Overall, 91% of children had an improvement in AHI, and 64% had only mild or no residual OSAS after supraglottoplasty. Supraglottoplasty is an effective technique for the treatment of OSAS associated with occult laryngomalacia.

 

Ambulatory anesthesia aspects for tonsillectomy and abrasion in children.  Raeder J Curr Opin Anaesthesiol. 2011 Dec;24(6):620–6.
http://www.ncbi.nlm.nih.gov/pubmed/21897214

Preoperative evaluation should identify increased bleeding risk, potential airway problems, ongoing infection and symptoms of OSA. IV propofol is most often used for anesthetic induction, although inhalational sevoflurane is a valid alternative. LMA or endotracheal tube may both be used safely and effectively; the choice will depend upon the routine and experience of the team. Paracetamol and NSAIDs are useful baseline medication for nonopioid multimodal postoperative pain treatment and prophylaxis. Similar with local anesthesia infiltration and dexamethasone medication, although somewhat more disputed.

 

The Childhood Adenotonsillectomy Trial (CHAT): rationale, design, and challenges of a randomized controlled trial evaluating a standard surgical procedure in a pediatric population.  Redline S, Amin R, Beebe D, Chervin RD, Garetz SL, Giordani B, Marcus CL, Moore RH, Rosen CL, Arens R, Gozal D, Katz ES, Mitchell RB, Muzumdar H, Taylor HG, Thomas N, Ellenberg S. Sleep. 2011 ;34(11):1509–17.
http://www.ncbi.nlm.nih.gov/pubmed/22043122

This paper addresses key elements in the design and implementation of a controlled trial for a widely used “standard practice” surgical intervention in a pediatric population, that include establishment of standardized data collection procedures across sites for a wide variety of data types, establishment of equipoise, and approaches for minimizing unblinding of selected key personnel.

 

Glucoregulatory consequences and cardiorespiratory parameters in rats exposed to chronic-intermittent hypoxia: effects of the duration of exposure and losartan.  Fenik VB, Singletary T, Branconi JL, Davies RO, Kubin L. Front Neurol. 2012;3:51. Epub 2012 Apr 9.
http://www.ncbi.nlm.nih.gov/pubmed/22509173

Treatment with CPAP may ameliorate pre-diabetic conditions in OSA patients, in part, by reducing sympathoexcitatory effects of recurrent nocturnal hypoxia.

  

Evidence for neuronal desynchrony in the aged suprachiasmatic nucleus clock. Farajnia S, Michel S, Deboer T, Vanderleest HT, Houben T, Rohling JH, Ramkisoensing A, Yasenkov R, Meijer JH.  J Neurosci. 2012;32(17):5891–9.
http://www.ncbi.nlm.nih.gov/pubmed/22539850

Aging leads to a deterioration of circadian rhythms in physiology and behavior. These authors analyzed circadian rhythms in the course of aging on different levels of organization. They were able to show that aging affects the suprachiasmatic nucleus at the network level organization as opposed to the single cell membrane deterioration “theory”.

 

GABAergic processes within the median preoptic nucleus promote NREM sleep. Benedetto L, Chase MH, Torterolo P.  Behav Brain Res. 2012 Mar 30;232(1):60–65.
http://www.ncbi.nlm.nih.gov/pubmed/22483998

In the present study the authors demonstrated the presence of GABAergic neurons in the median peptic nucleus of the cat that play a role in the generation and maintenance of NREM sleep.

 

Assessing REM sleep in mice using video data.  McShane BB, Galante RJ, Biber M, Jensen ST, Wyner AJ, Pack AI.  Sleep. 2012;35(3):433–42.
http://www.ncbi.nlm.nih.gov/pubmed/22379250

Due to technical challenges, monitoring sleep in animal models is always a difficult task. These authors presented a promising alternative high-throughput strategy using video analysis. This technique could obviate the need for EEG/EMG recording in distinguishing NREM from REM sleep.

 

Health effects of identifying patients with undiagnosed obstructive sleep apnea in the preoperative clinic: a follow-up study. Vanita Mehta, Rajeev Subramanyam, Colin M. Shapiro, Frances Chung Can J Anesth/J Can Anesth (2012) 59:544–555.
http://www.springerlink.com/content/3115140lqt534865/

The preoperative patients who were identified to have OSA and were compliant with CPAP use may have health benefits in terms of improved snoring, sleep quality, and daytime sleepiness. The CPAP compliant patients had a greater reduction in medication for comorbidities than the CPAP non-compliant or other treatment group. Timely diagnosis and treatment compliance may reduce symptoms of OSA and severity of associated comorbidities along with a reduction in medications.

 

Impact of smoking on perioperative pulmonary and upper respiratory complications after laparoscopic gynecologic surgery. Graybill WS, Frumovitz M, Nick AM, Wei C, Mena GE, Soliman PT, Dos Reis R, Schmeler KM, Ramirez PT. Gynecol Oncol. 2012 Mar 17. [Epub ahead of print].
http://www.ncbi.nlm.nih.gov/pubmed/22433464

The authors retrospectively identified all patients who underwent laparoscopic gynecologic surgery at one institution for 9 years and analyzed them by smoking status. The rate of pulmonary complications was 2.1% (12 of 564 patients) in never smokers, 4.5% (7 of 156 patients) in past smokers, and zero in current smokers.”

 

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