Problem Based Learning Discussion: Perioperative management of the child with obstructive sleep apnea

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1 Problem Based Learning Discussion: Perioperative management of the child with obstructive sleep apnea Moderators: Allison Fernandez MBA MD and Deborah Schwengel MD Institution: Johns Hopkins School of Medicine Objectives: At the completion of this session, learners will be able to: 1. Describe the clinical features of pediatric OSA 2. Discuss the anesthetic options for the outpatient tonsillectomy patient 3. Discuss criteria for ambulatory surgery vs. post-operative admission for pediatric OSA patients 4. Discuss future research in the area of OSA Case History: 37 month female, weight 13 kg, scheduled for an adenotonsillectomy and bilateral ear tubes in an outpatient facility. The child has a history of loud snoring, hyperactivity and multiple ear infections. Parents state that they have not witnessed apnea while she is sleeping but are impressed by her snoring and that it has been getting worse over the past year. She has no other medical problems and no drug allergies. The child s older sibling also had snoring that was treated with T&A. A sleep study was not obtained prior to surgery. What is Obstructive Sleep Apnea (OSA)? What are the systemic considerations for OSA? How to diagnose OSA? OSA is a disorder characterized by periodic, partial or complete obstruction of the upper airway during sleep. The patient usually arouses during sleep to improve the patency of the airway. This repetitive sleep disruption is especially common during REM sleep in children and can produce hypoxemia, hypercarbia, disruption of sleep architecture and long term may result in pulmonary hypertension. The gold standard test for diagnosis of OSA is overnight polysomnography (PSG). PSG is expensive, inconvenient, not readily available in all communities and not always scored appropriately for pediatric patients; an alternative method of screening is nocturnal oximetry. PSG is utilized to make a diagnosis and judge severity by scoring the number of events per hour and by measuring severity of hypoxemia and hypercarbia. (For more discussion of measurement parameters and PSG scoring please read in Schwengel 3 ) It does not predict which patients will have adverse outcomes postoperatively, but severity is linked to adverse perioperative events. Numerous studies including a recent study by Jaryszak 4 attempts to use PSG to predict postoperative outcomes and found that a high apnea-hypopnea index, high hypopnea index, low nadir oxygen saturation and high BMI were associated with adverse events. There are questionnaires that might be useful screening tools for pediatric patients, however none are validated as a diagnostic tool. An OSA identification and assessment to determine perioperative risk was developed by the ASA Task Force on OSA and was published in This questionnaire focuses on identification and stratification of OSA in patients to improve perioperative care. Some of the signs and symptoms to identify OSA include physical characteristics such as BMI, neck

2 circumference, craniofacial abnormalities, anatomical nasal obstruction, hypertrophic tonsils and history of snoring, apnea during sleep, frequent arousal, somnolence during daytime. Although this is a useful tool it only correlates clinically to PSG 55% of the time 1, and it is a tool designed to estimate risk in both adult and pediatric patients. Diagnostic criteria are different in adults and children and OSA in non-obese children should be considered a different disorder than in adults or obese children. Childhood vs. adult obstructive sleep apnea syndrome features 3 Children Adults Presentation Age 2 6-year peak Increased elderly Gender Male = female Males > females Obesity Few Most Tonsils & adenoids Often enlarged Rarely enlarged Daytime sleepiness Sleep Obstruction Less common than in adults but can be seen Obstructive apnea or hypoventilation Common Obstructive apnea Sleep architecture Usually normal Decreased delta and REM Arousals with obstruction May not be seen At end of each apnea Treatment Surgical Definitive therapy in most patients Minority of cases with inconsistent results Medical (positive airway pressure) Selected patients Most common therapy REM, rapid eye movement. Adapted from Sterni LM, Tunkel DE. Obstructive sleep apnea in children: An update. Pediatr Clin North Am 2003;50(2):

3 Which OSA patients are at increased risk for respiratory complications in the post operative period? Are specific anesthetic techniques associated with poor outcomes in patients with OSA? Current data indicate that children with OSA are at increased risk for post operative respiratory complications especially if it is severe OSA. In a review of medical malpractice cases, Morris found that children had more fatal respiratory failure events after T &A than adults (25 fatalities in children vs 11 in adults) 5. Most authors agree that children less than 3 years of age are at particular risk and are not candidates for outpatient surgery. Don et al published that children < 2 years of age are more likely to be diagnosed with severe OSA therefore are at increased risk for postoperative respiratory failure. Children with other comorbidities such as former prematurity, asthma, obesity, trisomy 21, craniofacial and neurological abnormalities are also at increased risk for complications in the postoperative period and have an increased risk of ongoing OSA despite treatment with T&A. Brown et al studied post-operative complications of urgent tonsillectomies and found that comorbid conditions and severe OSA defined as SaO2 nadir <80% are associated with increased respiratory complications in the post operative period. This study also found a 20% incidence of major respiratory complications in the study group with 11% requiring reintubation and 9.3% post operative pneumonia 10. Finally, obesity is another comorbidity frequently related to or causing OSA. In the US the definition for overweight children is BMI >85% th percentile and childhood obesity is BMI > 95% th percentile 9 and 32% of children in the US are overweight 9. According to Verhulst 13-59% of obese children are diagnosed with OSA by PGS 7. Obese children with snoring or OSA have increased inflammation of their airway 8. However, obese children without OSA did not have an increase in airway inflammation 8. Specific anesthetic techniques have not been correlated with poor outcomes in the postoperative period. However, OSA patients are known to be sensitive to opioids and more likely to become apneic with higher doses. In fact, Brown et al have shown that children with severe OSA don t even need the same opioid doses post-operatively 11. Despite the significant pain of the operation, these children are more comfortable with lower opioid doses. Brown et al. found that among patients with OSA, young age and lower oxygen nadir correlated with the requirement of lower opioid dose in the post operative period 11. In a follow up prospective study Brown found that children with an oxygen saturation nadir <85% required half the amount of analgesic as those with an oxygen saturation nadir >85% 12. This study assigned patients to receive standard morphine dose (0.1 mg/kg) or a calculated dose based on patient s age and nadir oxygen desaturation 50% of ( * age (months))+ ( * saturation nadir (%)) mg/kg 12. From this study one can infer that the standard morphine dose in severe OSA patients is an overdose. Another important teaching point is that codeine requires metabolism to morphine by the CYP2D system in the liver in order to be effective. The genetics of the CYP2D enzyme system is known. We know that some patients are homozygotes or heterozygotes for enzyme deficiencies resulting in slow or absent metabolism of codeine to morphine. Additionally, some patients are rapid metabolizers, resulting in rapid conversion to

4 morphine and higher than normal blood levels after administration. We do not recommend the use of codeine because of this inter-individual variation. Oxycodone is preferable alternative. Dexamethasone is routinely used to reduce incidence of post-operative nausea and vomiting. In one study the use of high doses was incidentally related to bleeding in tonsillectomy patients 16. However, high doses are not required to produce an anti-emetic effect 15. Dexamethasone might additionally provide an analgesic effect but more research is needed to determine the effective dose and mechanism of effect. Finally, Nixon et al looked at the sleep and breathing patterns with PSG of OSA patients who had undergone a tonsillectomy that day. The results of this small study demonstrated that all patients had obstructive events that night. The severe OSA group had a desaturation index of 9.3 and an AHI of 21 compared to 1.8 and 6.9 respectively in the mild OSA group 13. Interestingly, in all children the post operative AHI was higher during REM sleep. These findings suggest that patients with severe OSA warrant an overnight hospital stay. Future research: Risk stratification of patients based on PSG studies. Development of protocols to decrease respiratory complications in patients with severe OSA Raghavendran et al compared OSA patients undergoing tonsillectomy following the anesthetic standard practice in 2001 to tonsillectomy patients after an anesthetic protocol was implemented to risk stratify severe OSA patients. Patients were stratified into OSA 2, 3 or 4 based on the McGill Oximetry Score of SaO2 <90%, 85% and 80% respectively. If the patient did not meet these requirements they underwent PSG to determine if the patient had mixed/ obstructive apnea /hypopnea > 1 event per hour. If the child had an event <1 per hour they were assigned to the OSA 1 group. Their revised guidelines include: admission of OSA 4 patients to the PICU, administration of atropine after induction, dexamethasone (0.3 mg/kg), codeine (1 mg/kg) PRN for pain and reduced opioid doses intraoperatively and postoperatively. The authors found 29.6% of patients required a major respiratory medical intervention in the historical group compared to 11.3% in the revised guidelines group 14. Additionally, the OSA 4 group in the revised guidelines received lower total opioid dosing and still achieved optimal pain control as assessed by the Children s Hospital Eastern Ontario Pain Scale (CHEOPS). In addition 54% of the OSA 4 group patients received dexamethasone under the revised guidelines; they were discharged on postoperative day 1. As of now we can identify patients who are at increased risk of complications after a tonsillectomy. Several studies have identified age, comorbidities, opioid doses, severe OSA and obesity as risk factors for complications in the postoperative period after tonsillectomy. However, are there other ways to identify risk factors? Jaryszak attempted to identify risk factors for postoperative respiratory complications in patients undergoing tonsillectomy using their preoperative PSG. In this study there was a 15% respiratory complication rate following tonsillectomy. A regression analysis of the data revealed that patients who suffered a postoperative respiratory complication had the following risk

5 factors: BMI greater than 95%, 31.8 apnea hypopnea index, 22.6 hypopnea index and a nadir oxygen saturation of 74% 4. Further research is necessary to identify patients at risk of developing postoperative respiratory complications. PSG in the preoperative period may be a useful tool to help identify these patients. However, most patients do not receive a PSG because of expense, inconvenience of the study and length of study. Other techniques to identify high risk patients undergoing tonsillectomy will further improve patient safety in the post operative period. We must also mention that neither an uncomplicated intraoperative course nor an uncomplicated PACU stay can prove that a child with OSA is safe for discharge 1. Although the mortality for T&A is low, it is not zero. Perioperative respiratory complications for children with OSA pose real risk. Children with severe OSA, comorbidities, age < 3 or morbid obesity must not be discharged on the day of surgery. References 1. Brown K. Outcomes, risk, and error and the child with obstructive sleep apnea. Pediatic Anesthesia 2011; 21: Practice Guidelines for the perioperative Management of patients with obstructive sleep apnea: A report by the American Society of Anesthesiologists Task Force Perioperative Management of Patients with Obstructive Sleep Apnea. Anesthesiology2006;104(5): Schwengel DA, Sterni LM, Tunkel DE and Heitmiller ES. Perioperative management of children with obstructive sleep apnea. Anesthesia and Analgesia 2009;109(1): Jaryszak E, Shah R, Vanison C, Lander L, Choi S. Polysomnographic variables predicitive of adverse respiratory events after pediatric adenotonsillectomy. Archives of Otolaryngology Head and Neck Surgery 2011;137(1): Morris LGT, Lieberman SM, Reitzen SD. Characteristics and outcomes of malpractice claims after tonsillectomy. Otolaryngology Head and Neck Surgery 2008;138: Don Dm, Geller KA, Koempel JA Age specific differences in pediatric obstructive sleep apnea. International Journal of Otorhinolaryngol 2009;73: Verhulst SL,Van Gall L, De Backer W. The prevalence, anatomical correlates and treatment of sleep-disordered breathing in obese children and adolescents. Sleep Medicine Review 2008;12: Verhulst SL, Aerts L, Jacobs S, Schrauwen N, Haentjens D, Claes R, Vaerenberg H, Van Gaal LF, De Backer W, Desager K. Sleep-disordered breathing, obesity, and airway inflammation in children and adolescents. Chest 2008;134(6) Mortensen A, Lenz K, Abilstrom H and Lauristen T. Anesthetizing the obese child. Pediatric Anesthesia 2011;21: Brown K, Morin I, Hickey C, Manoukian J, Nixon G and Brouillette R. Urgent Adenotonsillectomy An analysis of risk factors associated with postoperative respiratory morbidity. Anesthesiology 2003;99:

6 11. Brown K, Laferriere A and Moss I. Recurrent hypoxemia in young children with obstructive sleep apnea is associated with reduced opioid requirement for analgesia. Anesthesiology 2004;100: Brown K, Laferriee A, Lakheeram I and Moss I. Recurrent hypoxemia in childrens is associated with increased analgesic sensitivity to opiates. Anesthesiology 2006;105: Nixon GM, Kermack AS, McGregor CD, Davis GM, Manoukian JJ, Brown KA, Brouillette RT. Sleep and breathing on the first night after adenotonsillectomy for obstructive sleep apnea. Pediatirc Pulmonology 2005;39(4): Raghavendran S, Bagry H, Detheux G, Zhang X, Brouillette R and Brown K. An anesthetic management protocol to decrease respiratory complications afer adenotonsillectomy in children with severe sleep apnea. Anesthesia and Analgesia 2010;110(4): Kim MS, Coté CJ, Cristoloveanu C, Roth AG, Vornov P, Jennings MA, Maddalozzo JP, Sullivan C. There is no dose-escalation response to dexamethasone ( mg/kg) in pediatric tonsillectomy or adenotonsillectomy patients for preventing vomiting, reducing pain, shortening time to first liquid intake, or the incidence of voice change. Anesthesia &Analgesia 2007;104(5): Czarnetzki C, Elia N, Lysakowski C, Dumont L, Landis BN, Giger R, Dulguerov P, Desmeules J, Tramèr MR. Dexamethasone and risk of nausea and vomiting and postoperative bleeding after tonsillectomy in children: a randomized trial. Journal of American Medical Association 2008;10(22):