Featured Article — May 2012
Tajender Vasu, Kimmo Murto, Raviraj Raveendran
Postoperative complications in patients with obstructive sleep apnea
Kaw R, Pasupuleti V, Walker E, Ramaswamy A, Foldvary-Schafer N. Chest 2012; 141 (2): 436–41 http://www.ncbi.nlm.nih.gov/pubmed/21868464
In this historical cohort study, the authors included patients undergoing non-cardiac surgery within 3 years of polysomnography. They excluded patients with age < 18 years, patients with history of upper airway surgery, and minor surgery under local or regional anesthesia. There were 471 patients who met the study criteria. The medical record of these patients was reviewed to identify postoperative complications including hypoxemia, respiratory failure, congestive heart failure, myocardial infarction, delirium, hospital length of stay, and death within 30 days.
There were 281 patients with OSA (AHI ≥ 5/hr) and 189 patients without OSA. For adjusting baseline differences in age, sex, race, BMI, type of anesthesia, American Society of Anesthesiology class and medical co-morbidities, the patients were classified into five quintiles according to a propensity score. Interestingly, OSA was associated with a higher incidence of postoperative hypoxemia (OR= 7.9), overall complications (OR= 6.9); ICU transfer (OR 4.43) and higher length of hospital stay, (OR= 1.65). There are many other studies that have shown OSA to be a risk factor for perioperative complications. Due to the increased prevalence of OSA in surgical population, it is very important to identify these patients preoperatively.
High STOP-Bang score indicates a high probability of obstructive sleep apnea
Chung F, Subramanyam R, Liao P, Sasaki E, Shapiro C, Sun Y. Br J Anaesth 2012; 108: 768–75 http://www.ncbi.nlm.nih.gov/pubmed/22401881
Can we identify a patient at high-risk for OSA by using a questionnaire? There are three questionnaires that have been validated in the surgical population to identify patients with underlying OSA: the Berlin questionnaire, STOP-Bang questionnaire, and ASA checklist.
The STOP-bang questionnaire consists of eight yes/no questions and is very easy to administer preoperatively. A score of ≥ 3 is very sensitive in identifying patients with moderate to severe OSA: 93% and 100% in identifying patients with moderate and severe OSA, respectively. However, at this cut-off, the questionnaire is not very specific and therefore includes many false positives.
In this study, Dr. Chung et al administered the STOP-bang questionnaire to patients undergoing elective inpatient surgery. These patients also underwent in-lab or type 2 home sleep studies. There were 746 patients with complete data for the analysis. The OSA was present in 68.4% with 29.9% mild, 20.5% moderate, and 18.0% severe OSA. For a STOP-Bang score of 5, the odds ratio (OR) for moderate/severe and severe OSA was 4.8 and 10.4, respectively. For STOP-Bang 6, the OR for moderate/ severe and severe OSA was 6.3 and 11.6, respectively. For STOP-Bang 7 and 8, the OR for moderate/severe and severe OSA was 6.9 and 14.9, respectively. Therefore, the STOP-bang questionnaire can be used to identify OSA in patients undergoing elective surgery. Interestingly, the likelihood of having moderate or severe OSA increased with each point increase in the STOP-bang score.
Clinical practice guideline: Polysomnography for sleep-disordered breathing prior to tonsillectomy in children.
Roland PS, Rosenfeld RM, Brooks LJ, Friedman NR, Jones J, Kim TW, Kuhar S, Mitchell RB, Seidman MD, Sheldon SH, Jones S, Robertson P; American Academy of Otolaryngology-Head and Neck Surgery Foundation. Otolaryngol Head Neck Surg. 2011;145(1 Suppl):S1-15. Epub 2011 Jun 15 http://www.ncbi.nlm.nih.gov/pubmed/21676944
This guideline provides otolaryngologists with evidence-based recommendations for using polysomnography (PSG) in assessing children, aged 2 to 18 years, with sleep-disordered breathing and are candidates for tonsillectomy, with or without adenoidectomy. The primary purpose of this guideline is to improve referral patterns for PSG among these patients.
The committee made the following recommendations: (1) before determining the need for tonsillectomy, the clinician should refer children with sleep-disordered breathing (SDB) for PSG if they exhibit certain complex medical conditions such as obesity, Down syndrome, craniofacial abnormalities, neuromuscular disorders, sickle cell disease, or mucopolysaccharidoses. (2) The clinician should advocate for PSG prior to tonsillectomy for SDB in children without any of the comorbidities listed in statement 1 for whom the need for surgery is uncertain or when there is discordance between tonsillar size on P.E. and the reported severity of SDB. (3) Clinicians should communicate PSG results to the anesthesiologist prior to the induction of anesthesia for tonsillectomy in a child with SDB. (4) Clinicians should admit children with OSA documented on PSG for inpatient, overnight monitoring after tonsillectomy if they are younger than age 3 or have severe OSA (AHI of 10 or more obstructive events/h, O2 saturation nadir <80%, or both). (5) In children for whom PSG is indicated to assess SDB prior to tonsillectomy, clinicians should obtain laboratory-based PSG, when available.
Difficult Airway Society Guidelines for the management of tracheal extubation.
Popat M, Mitchell V, Dravid R, Patel A, Swampillai C, Higgs A. Anaesthesia 2012, 67, 318–340 http://www.ncbi.nlm.nih.gov/pubmed/22321104
This guideline is aimed to reduce the morbidity and mortality related to extubation by following a stepwise approach. From the fourth National Audit Project (NAP4) of the Royal College of Anaesthetists and the US closed claim study, it is vivid that extubation needs more attention. Compared to induction and intubation practice, lack of high grade clinical evidence in extubation practice has limited the authors to rely on expert opinion on many issues.
The guideline has three algorithms and each algorithm has four similar steps with different focus. The four steps are plan extubation, prepare for extubation, perform extubation and post extubation care. The core focus of the “basic algorithm” is stratification of extubation as “low risk” and “at risk”, based on the assessment of general and airway risk factors. The “low risk algorithm” mainly focusing on deep vs. awake extubation. The “at risk algorithm” has the key focus on awake vs. advanced techniques of extubation and postpone extubation vs. tracheostomy. The advanced techniques are laryngeal mask exchange, remifentanil technique and the airway exchange catheter.
This guideline has been formatted in such a way that would be useful in day to day practice. It is clearly emphasized that extubation is an elective process and planning is imperative.
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