Outline. Major variables contributing to airway patency/collapse. OSA- Definition

Transcription

1 Outline Alicia Gruber Kalamas, MD Associate Clinical Professor of Anesthesia & Perioperative Care University of California, San Francisco September 2011 Definition Pathophysiology Patient Risk Factors Implications for the Perioperative Period Preoperative Screening ASA Guidelines OSA- Definition OSA = partial or complete obstruction of the upper airway and it is characterized by episodes of cessation of breathing during sleep lasting for more than 10 s Major variables contributing to airway patency/collapse Apnea Hypopnea Index (AHI) is the number of episodes of apnea or hypopnea per hour during sleep Accepted minimal clinical diagnostic criteria for OSA = AHI of 10 plus symptoms of excessive daytime sleepiness In the presence of conditions like, hypertension, CHF (congestive heart failure), daytime sleepiness, mood disorders and insomnia, an AHI of 5 suggestive of sleep apnea Polysomnography (PSG) is the gold standard for diagnosis 1

2 Pathophysiology of OSA Anatomy Its small (Obesity/micrognathia = crowding of normal pharyngeal structures into a smaller bony compartment) Control Kept patent pharyngeal dilator muscles (e.g. genioglossus) Negative airway pressure primary stimulus to these muscles During sleep, negative-pressure reflex substantially attenuated Pharyngeal dilator muscles can compensate for the deficient airway anatomy of the patient with sleep apnea during wakefulness but not sleep White DP, Sleep Apnea, Proc Am Thorac Soc, Vol 3, pp , 2006 White DP, Pathogenesis of Obstructive and Central Sleep Apnea, AJRCCM, 172, , 2005 Prevalence General population, moderately severe OSA (AHI >15) 11.4% men; 4.7% women General surgical population- unknown Few studies looked at prevalence by type of surgery 7 of every 10 patients undergoing bariatric surgery OSA Patient Risk Factors Age Obesity Gender Tobacco HTN DM Hypothyroidism Implications for the Perioperative Period Anesthesia & Analgesia2011 National Inpatient Sample (NIS) (largest all-payer database US). All patients lower extremity joint arthroplasty or an open abdominal surgical procedure 1998 and 2007 identified 3,441,262 general surgical 2,610,441 orthopedic ICD-9 codes used to identify pts with known sleep apnea 1.4% 2.52% Primary outcomes: Aspiration pneumonia, adult respiratory distress syndrome (ARDS), pulmonary embolism (PE),and the need for intubation and mechanical ventilation Stavros Memtsoudis et al, Perioperative Pulmonary Outcomes in Patients with Sleep Apnea After Noncardiac Surgery A & A January 2011 vol. 112 no

3 Sleep Apnea is an independent risk factor for perioperative pulmonary complications Preoperative Screening Questionnaires Flemons Criteria Berlin questionnaire ASA Task Force 16-Item Check List STOP STOP-BANG Berlin Questionnaire Category 1 1. Do you snore? c. Don't know If you snore: 2. Your snoring is: a. Slightly louder than breathing b. As loud as talking c. Louder than talking d. Very loud-can be heard in adjacent rooms 3. How often do you snore? 4. Has your snoring ever bothered other people? c. Don't know 5. Has anyone noticed that you quit breathing during your sleep? Category 2 6. How often do you feel tired or fatigued after your sleep? 7. During your waking time, do you feel tired, fatigued, or not up to par? 8. Have you ever nodded off or fallen asleep while driving a vehicle? If yes: 9. How often does this occur? Category Do you have high blood pressure? c. Don't know 3

4 Berlin Questionnaire- Scoring Category 1: items 1, 2, 3, 4, and 5 Item 1: If yes is the response, assign 1 point. Item 2: If c or d is the response, assign 1 point. Item 3: If a or b is the response, assign 1 point. Item 4: If a is the response, assign 1 point. Item 5: If a or b is the response, assign 2 points. Category 1 is positive if the total score is 2 or more points. Category 2: items 6, 7, and 8 (item 9 should be noted separately) Item 6: If a or b is the response, assign 1 point. Item 7: If a or b is the response, assign 1 point. Item 8: If a is the response, assign 1 point. Category 2 is positive if the total score is 2 or more points. Category 3 is positive if the answer to item 10 is yes or if the BMI of the patient is greater than 30 kg/m 2. High risk of OSA: two or more categories scored as positive Low risk of OSA: only one or no category scored as positive ASA taskforce 16-item checklist Category 1: Predisposing Physical Characteristics a. BMI 35 kg/m 2 b. Neck circumference >43 cm/17 inches (men) or 40 cm/16 inches (women) c. Craniofacial abnormalities affecting the airway d. Anatomical nasal obstruction e. Tonsils nearly touching or touching the midline Category 2: History of Apparent Airway Obstruction during Sleep Two or more of the following are present (if patient lives alone or sleep is not observed by another person, then only one of the following need be present): a. Snoring (loud enough to be heard through closed door) b. Frequent snoring c. Observed pauses in breathing during sleep d. Awakens from sleep with choking sensation e. Frequent arousals from sleep Category 3: Somnolence One or more of the following are present: a. Frequent somnolence or fatigue despite adequate sleep b. Falls asleep easily in a nonstimulating environment (e.g., watching TV, reading, riding in or driving a car) despite adequate sleep c. [Parent or teacher comments that child appears sleepy during the day, is easily distracted, is overly aggressive, or has difficulty concentrating]* d. [Child often difficult to arouse at usual awakening time]* ASA taskforce 16-item checklist-scoring If two or more items in category 1 are positive, category 1 is positive. If two or more items in category 2 are positive, category 2 is positive. If one or more items in category 3 are positive, category 3 is positive. High risk of OSA: two or more categories scored as positive Low risk of OSA: only one or no category scored as positive STOP Questionnaire Peri-operative population Borrowed from Berlin questionnaire Validation study-1875 patients All patients invited for sleep study Correlate predictive parameters vs AHI The questions... 4

5 STOP Questionnaire Sensitivities STOP Questionnaire S: Do you snore loudly (louder than talking or loud enough to be heard through closed doors)? T: Do you often feel tired, fatigued or sleepy during the day? O: Has anyone observed you not breathing during sleep? P: Do you have or have you been treated for high blood pressure? Sensitivities of the STOP: - AHI> % - AHI > % - AHI > % Yes to two or more questions = high risk of having OSA STOP vs. Berlin vs. ASA Checklist STOP Berlin ASA AHI > AHI > AHI > STOP-BANG Questionnaire Incorporate body mass index, age, neck circumference, and gender (BANG): BMI more than 35 kg/m2? Are you over 50 years old? Neck circumference greater than 40cm? Gender (Male)? Yes to three or more questions = high risk of having OSA Sensitivities of the STOP-BANG: -AHI> % - AHI > % - AHI >30 100% Chung F, Yegneswaran B, Liao P, et al, Validation of the Berlin Questionnaire and American Society of Anesthesiologists Checklist as Screening Tools for Obstructive Sleep Apnea in Surgical Patients Anesthesia, 2008, 108:

6 Preoperative Screening: STOP-BANG Sens Spec PPV NPV AHI > AHI > AHI > ASA Guidelines PRE-OPERATIVE Protocol should be developed whereby patients with the possibility of OSA are evaluated long enough before the day of surgery to allow preparation of a perioperative plan. Preoperative initiation of CPAP should be considered, particularly if OSA is severe. A preoperative determination must be made regarding whether surgery should be performed on an inpatient or outpatient basis. Local anesthesia and peripheral blocks should be considered for superficial procedures Major conduction anesthesia (spinal/epidural) should be considered for peripheral procedures ASA Task Force, Practice Guidelines for the Perioperative Management of Patients with OSA, Anesthesiology, 104, , 2006 ASA Guidelines INTRA-OPERATIVE With moderate sedation capnography should be considered to monitor for airway obstruction. Unless there is a contraindication, patients at increased perioperative risk from OSA should be extubated while awake with full reversal of neuromuscular block verified before extubation. Extubation and recovery should be carried out in the non-supine position. ASA Guidelines POST-OPERATIVE Regional analgesic techniques should be considered Exclusion of opioid analgesics reduces risk compared with neuraxial techniques which include opioids and should be considered. CPAP or NIPPV should be administered as soon as is feasible after surgery to patients with OSA who are receiving it preoperatively. Consultants were equivocal on institution in patients not previously treated. Continuous oxymetry reduces likelihood of perioperative complications and should be maintained following discharge from recovery room. ASA Task Force, Practice Guidelines for the Perioperative Management of Patients with OSA, Anesthesiology, 104, , 2006 ASA Task Force, Practice Guidelines for the Perioperative Management of Patients with OSA, Anesthesiology, 104, ,

7 Perioperative Evaluation and Management Pre-operative Management: Screen for risk pre-operatively STOP STOP-BANG Intra-operative Management OR Post-operative Management PACU Floor management 7