Perioperative Management of Obstructive Sleep Apnea BY

1. Perioperative Management of Obstructive Sleep Apnea BY AHMAD YOUNESPROFESSOR OF THORACIC MEDICINE Mansoura Faculty of Medicine

2. SLEEP DISORDERED BREATHING The standard parameters used to record sleep and wake are electroencephalography (EEG), electro-oculography (EOG), electromyography (EMG), airflow measurement, respiratory effort measurement, electrocardiography (ECG), oxygen saturation, snoring monitor, and sleep position evaluation. All these parameters are recorded in polysomnography which is the gold standard for diagnosis of Sleep disordered breathing .

4. Types of Sleep disordered breathing includes : 1-Obstructive sleep apnea syndrome in which inadequate ventilation occurs despite continued efforts to breath due to upper airway obstruction. 2- Central sleep apnea syndrome in which inadequate ventilation occurs resulting from absent or diminished respiratory effort. 3-Sleep hypoventilation syndrome in which > 10 mm Hg increase in PaCO2 during sleep in comparison with an awake supine value.

6. Apnea: is defined as the drop in peak airflow by >90% of baseline for 10 seconds or longer and at least 90% of the event duration meet the amplitude reduction. An obstructive apnea occurs when airflow is absent or nearly absent, but ventilatory effort persists. It is caused by complete, or near complete, upper airway obstruction

7. A central apnea occurs when both airflow and ventilatory effort are absent.

8. During a mixed apnea, there is an interval during which there is no respiratory effort (ie, central apnea pattern) and an interval during which there are obstructed respiratory efforts .

9. Hypopnea  • Hypopnea be scored when all of the following four criteria are met: • Airflow decreases at least 30 percent from baseline • There is diminished airflow lasting at least 10 seconds • at least 4 percent oxyhemoglobin desaturation . or • Airflow decreases at least 50 percent from baseline • There is diminished airflow lasting at least 10 seconds • 3 percent oxyhemoglobin desaturation or an arousal Apnea-hypopnea index  (AHI) is the total number of apneas and hypopneas per hour of sleep.

10. SLEEP DISORDERED BREATHING SYNDROMES 1- Obstructive sleep apnea syndrome (OSA) in adults is defined as either • More than 15 apneas, hypopneas, per hour of sleep ( AHI >15 events/hr) in an asymptomatic patient OR • More than 5 apneas, hypopneas, per hour of sleep (AHI >5 events per hour) in a patient with symptoms (eg, sleepiness, fatigue and inattention) or signs of disturbed sleep (snoring, restless sleep, and respiratory pauses).

11. 2- Central sleep apnea syndrome (CSAS) can defined as: a. Study showing AHI > 5 events/hr. and b. CentralAHI > 50% of the total AHI, and c. Central apneas or hypopneas >=5/hr., and d. Symptoms of either excessive sleepiness or disrupted sleep. 3- Sleep Hypoventilation Syndrome Score hypoventilation during sleep if there is a ≥10 mm Hg increase in PaCO2 during sleep in comparison with an awake supine value

12. OSA is the most prevalent sleep disorder in the adult population. • OSAis more common than bronchial asthma in adults ,affecting approximately 4% of men and 2% of women. • The prevalence of OSA is higher in patients presenting for surgery than in the general population e.g. moderate or severe OSA is prevalent in at least 50% of patients subjected to bariatric surgery , and a significant proportion of OSA patients remain undiagnosed when they present for surgery. • The presence of OSA is known to increase the occurrence of comorbid conditions ( hypertension , ischemic heart disease , diabetes melitus and stroke ) and postoperative complications . • It is the opinion of the American Society of Anesthesiologists Task Force that the perioperative risk to patients increases in proportion to the severity of sleep apnea.

13. OSA and postoperative complications In a recent retrospective study of elective non-cardiac procedures, the occurrence of postoperative complications was observed in 44% of patients with OSA versus 28% in patients with no OSA. Patients with OSA undergoing hip or knee replacement were at an increased risk of developing perioperative complications (24% versus 9%, respectively). An increased risk of postoperative complications was also observed in OSA patients undergoing upper airway and cardiac procedures . The most commonly observed complication was oxygen desaturation (17% in patients with OSA versus 8% with no OSA).

14. OSA and postoperative complications Proposed guidelines from the Adult OSA Task Force of the American Academy of Sleep Medicine suggest that : 1- Questions regarding OSA should be included in routine health screenings. 2-If OSA is suspected, a comprehensive sleep evaluation should be conducted. Interestingly, it was observed that OSA patients undergoing surgery hadhigher AHI and oxygen-desaturation index scores on the third postoperative night compared to the first postoperative night or preoperatively .

15. Perioperative Management Plan • Anesthesiologists should work with surgeons to develop a protocol whereby patients in whom the possibility of OSA is suspected on clinical grounds are evaluated long enough before the day of surgery to allow preparation of a perioperative management plan. • This evaluation may be initiated in a preanesthesia clinic (if available) or by direct consultation from the operating surgeon to the anesthesiologist. • The perioperative management of patients with OSA begins with preoperative identification ,after which plans are made to tailor specific preoperative ,intraoperative and postoperative care.

16. OSA symptoms

17. OSA signs

18. Screening for OSA prior to surgery • It is estimated that 82% of men and 92% of women with moderate-to-severe sleep apnea have not been diagnosed. • A substantial proportion of these patients present for surgery and may have an increased risk of perioperative complications. • The screening tools may assist in the diagnosis of OSA when associated with a high index of clinical suspicion. •  Snoring is a prime symptom of OSA and is almost 100% sensitive, however it lacks specificity and has a low positive predictive value.

19. Screening for OSA prior to surgery • A study screening preoperative patients using the Berlin Questionnaire determined that it had a sensitivity of 69% and a specificity of 56% in surgical patients. • Although validated in primary care settings, the Berlin Questionnaire is a complicated scoring system with a large number of questions. • The American Society of Anesthesiologistsdeveloped a tool in 2006 to help assist anesthesiologists in identifying patients with OSA. • It comprises a 14-item checklist categorized into history of airway obstruction during sleep , physical characteristics, and complaints of somnolence .

21. American Society of Anesthesiologists ChecklistHigh risk of OSA if 2 or more categories scored as positive.Low risk of OSA if 1 or no categories scored as positive

22. Screening for OSA prior to surgery • The sensitivity of the American Society of Anesthesiologists checklist was 79% at AHI of > 15 and 87% at AHI > 30. • A significant step forward in the screening of patients for OSA was the development of a more concise and easy-to-use bedside screening tool abbreviated as the STOP Questionnaire • The sensitivity of the STOP questionnaire with AHI > 15 and > 30 as cut-offs were 74% and 80% respectively. • The specificity at similar AHI levels was 53% and 49% respectively.

23. The STOP questionnaire

24. Screening for OSA prior to surgery • When combined with BMI, age, neck circumference, and gender, the STOP Questionnaire had a high sensitivity, especially for patients with moderate to severe OSA. • This combined version is commonly referred to as the STOP-Bang Questionnaire . • The use of the STOP-Bang Questionnaireimproved the sensitivity to 93%, and 100% at AHI cut-offs of >15 and >30 respectively, making it an ideal screening tool with a high sensitivity level. • The specificity of the STOP-Bang Questionnaire at similar AHI levels was 43% and 37% respectively.

25. The STOP-Bang scoring model.

26. Screening for OSA prior to surgery • Various other screening modalities including the modified Mallampatti score of 3 or 4, or a waist circumference of > 105 cm, have been correlated well with an increased AHI . • With analyzing the accuracy of clinical screening methods in the diagnosis of OSA (26 different clinical prediction tests with 8 in the form of questionnaires, and 18 algorithms, regression models or neural networks ), STOP-Bang Questionnaire was described as a user-friendly and excellent method to predict severe OSA (AHI >30). • The linear scale and the simple acronym make the STOP-Bang Questionnaire practical and easy-to-use in the preoperative setting. • STOP-Bang is now widely adopted as a screening tool for OSA in primary care settings, preoperative clinics and sleep clinics.

27. In the Mallampati maneuver, patients are instructed not to emit sounds but to open the mouth as wide as possible and protrude the tongue as far as possible. In the modified Mallampati, the patient is instructed to open the mouth as wide as possible without emitting sounds.

28. Screening for OSA prior to surgery • Nocturnal oximetry may be a sensitive and specific tool to detect OSA in surgical patients. • There was a strong correlation between nocturnal oximetry and the AHI from polysomnography . • The oxygen desaturation index measured by nocturnal oximetry had a sensitivity of 75-95% and a specificity of 67-97% as compared to AHI. • The availability of various screening modalities and an increasing awareness of the occurrence of OSA may lead to more patients being diagnosed with this challenging condition.

29. Nocturnal oximetry

31. Screening for OSA prior to surgery • Preoperative preparation can include the use of home sleep tests e.g. Apnea Link as a diagnostic tool for OSA. • The diagnostic gold standard remains polysomnography carried out overnight in a sleep clinic, often times this is an expensive, time-consuming option. • There frequently is not enough time from the date of scheduled surgery to obtain necessary authorizations and appointments for a PSG, resulting in the need for alternative diagnostic methods. • For the anesthesiologist who first suspects sleep apnea in a preoperative clinic for surgery scheduled several days in the future, the patient’s surgery would have to be cancelled and rescheduled pending the PSG and appropriate treatment

32. Apnea Link

33. Screening for OSA prior to surgery • Pulse oximetry as a single metric of sleep apnea lacks the sensitivity and specificity of PSGand multi-channel home sleep testing. • If the goal is only to cipher out those with an AHI of 15 or 20 or more, pulse oximetry can be considered. • Centers for Medicare and Medicaid Services, 2009 reported that the final decision supporting equally effective testing utilizing PSG and home sleep tests, as measured by outcomes and patient compliance. • While patients with mild OSA may not require preoperative PAP therapy, patients with moderate and severe OSA who have been on PAP therapy should continue treatment in the preoperative pe­riod . • Patients who have been noncompliant with instructions for CPAP use prior to surgery and are in need of CPAP post-surgery, pose the highest risk of potential complications.

34. Preoperative optimization of patients with known or suspected OSA • There are a substantial percentage of patients diagnosed with OSA who are often prescribed CPAP or BPAP devices. • The current use of CPAP or BiPAP should be noted with special care on compliance to therapy. • Patients should be advised to bring their CPAP devices to the hospital on the day of surgery for postoperative use. • A subset of patients may need reassessment preoperatively, especially patients with a known diagnosis of OSA but lost on follow-up, recent exacerbation of OSA symptoms, those who have undergone OSA-related airway surgery, or have been non-compliant with CPAP. • Experience suggests that restarting preoperative CPAP may be beneficial on non-compliant patients. • The American Society of Anesthesiologists task force on the management of OSA recommends that patients with moderate and severe OSA who have been on CPAP therapy should continue with CPAP in the postoperative period .

36. Preoperative optimization of patients with known or suspected OSA Precautions should be taken in anticipating the possibility of having a difficult airway Most patients may be obese and appropriate care should be taken to prevent desaturation. It is useful to employ short-acting anesthestic drugs, less soluble inhalational agents, titrate opioids, and minimize sedation. In patients with anticipated difficult airways, awake extubation may have to be performed preferably in a 30° to 45° head-up position. The routine perioperative care may be adequate for patients with mild OSA. If patients have any co-morbidities, they should be optimized. Patients may benefit by the modifications of anesthetic technique such as avoidance of general anesthesia in favor of a central neuraxial or a peripheral nerve block.

37. Preoperative optimization of patients with known or suspected OSA

38. Intra-operative optimization of patients with known or suspected OSA

39. Intra-operative optimization of patients with known or suspected OSA • Several issues can arise intraoperatively in the OSA patient, including difficult intubation, opioid-related respiratory depression, and excessive sedation; provides an overview of potential anesthetic concerns with the OSA patient . • Two important correlates of difficult intubation are a higher Mallampati score ≥ 3, neck circumference > 40 cm, or waist circumference > 105 cm ; same for both genders).

40. Intra-operative optimization of patients with known or suspected OSA • Proper positioning should include supporting the obese patient behind the upper back and head to achieve an anatomical position where a horizontal plane between the sternal notch and the external auditory meatus is established. • In patients with OSA, the sitting posture decreases the frequency of airway obstruction compared to supine, and the benefits from upright positioning are enhanced in the obese patient. • Placing patients into a sitting position for preoxygenation and anesthetic induction should be considered.

41. Intra-operative optimization of patients with known or suspected OSA • The obese patient has a reduced FRC, and tidal volume often falls below the closing capacity of the small airways, leading to atelectasis, increased intrapulmonary shunting, and impaired oxygenation. • FRC is further reduced after induction of anesthesia, when the weight of the anterior chest compresses the thorax. • At least three minutes of breathing 100% oxygen or five vital capacity breaths of 100% oxygen are essential. • For superficial procedures, one should consider the use of local anesthesia or peripheral nerve blocks, with or without moderate sedation. • If moderate sedation is used, ventilation should be continuously monitored by capnography or another automated method if feasible because of the increased risk of undetected airway obstruction in these patients.

42. Intra-operative optimization of patients with known or suspected OSA • One should consider administering CPAP during sedation to patients previously treated with these modalities. • General anesthesia with a secure airway is preferable to deep sedation without a secure airway, particularly for procedures that may mechanically compromise the airway. • Spinal/epidural anaesthesia should be considered for peripheral procedures. • Full reversal of neuromuscular block should be verified before extubation. When possible, extubation and recovery should be carried out in the lateral, semi-upright, or other non-supine position.

43. Intra-operative optimization of patients with known or suspected OSA

44. Post-operative optimization of patients with known or suspected OSA • Postoperative concerns in the management of patients with OSA include: • analgesia, (2) oxygenation (3)patient positioning (4) monitoring. • Risk factors for respiratory depression include the systemic and neuraxial administration of opioids, administration of sedatives, site and invasiveness of surgical procedure, and severity of the sleep apnea. • Postoperative residual curarization is common after administration of neuromuscular blocking agents. • Suggested practices include verification of full neuromuscular blockade recovery, ensuring the patient is fully conscious prior to extubation, and placing the patient in a semi-upright recovery position. Anticipating possible difficult airways, use of short-acting anesthetic agents, opioid minimization, reversal prior to extubation, and extubation in a non-supine position.

45. Post-operative optimization of patients with known or suspected OSA • Opioids suppress REM and slow wave sleep . • REM rebound contribute to haemodynamic instability , myocardial ischemia and infarction ,stroke ,mental confusion and wound breakdown. • Exacerbation of respiratory depression may occur on the third or fourth postoperative day as sleep patterns are reestablished and “REM rebound” occurs.

46. Post-operative optimization of patients with known or suspected OSA • Supplemental oxygen should be administered continuously to all patients who are at increased perioperative risk from OSA until they are able to maintain their baseline oxygen saturation while breathing room air. • The Task Force cautions that supplemental oxygen may increase the duration of apneic episodes and may hinder detection of atelectasis, transient apnea, and hypoventilation by pulse oximetry. • CPAP or BiPAP, with or without supplemental oxygen, should be continuously administered when feasible to patients who were using these modalities preoperatively, unless contraindicated by the surgical procedure.

47. Post-operative optimization of patients with known or suspected OSA • Compliance with CPAP or BiPAP may be improved if patients bring their own equipment to the hospital. • Intermittent pulse oximetry or continuous bedside oximetry without continuous observation does not provide the same level of safety. • If frequent or severeairway obstruction or hypoxemia occurs during postoperative monitoring, initiation of nasal CPAP or BiPAP should be considered.

48. Management of patients scheduled for ambulatory surgery • Due consideration must be given to 1- The type of surgery, 2- Associated co-morbidities, 3-Patient’s age 4- Severity of OSA 5-The treatment status 6-Anticipated use of postoperative opioids 7-The type of anesthesia (local vs general vs nerve blocks with or without sedation) and 8- Home care . • The American Society of Anesthesiologists Advisory Guidelines on the Perioperative management of patients with OSA suggests that superficial surgeries or minor orthopedic surgery using local or regional techniques, and lithotripsy, may be done on an ambulatory basis.

49. Consultant Opinions Regarding Procedures That May Be Performed Safely on an Outpatient Basis for Patients at Increased Perioperative Risk from OSA

50. Management of patients scheduled for ambulatory surgery • Patients with regional anesthesia also have elevated AHI and oxygen desaturation. This may imply that OSA patients need to be treated with CPAP. • Regarding ambulatory surgery, short-acting anesthetic agents and non-invasive surgery typically makes this a safer option for patients with OSA. • Severe untreated or undiagnosed OSA requiring postoperative narcotics after ambulatory surgery may be unsafe. • The consultants indicated that monitoring of patients with OSA should continue for a median of 7 h after the last episode of hypoxemia while breathing room air in an unstimulating environment.