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Obstructive sleep apnea (OSA)

Obstructive sleep apnea (OSA). OR Obstructive sleep apnea/hypopnea syndrome (OSAHS). www.anaesthesia.co.in anaesthesia.co.in@gmail.com. Definition. Recurrent episodes of partial or complete collapse of the upper airway during sleep.

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Obstructive sleep apnea (OSA)

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  1. Obstructive sleep apnea (OSA) OR Obstructive sleep apnea/hypopnea syndrome (OSAHS) www.anaesthesia.co.inanaesthesia.co.in@gmail.com

  2. Definition • Recurrent episodes of partial or complete collapse of the upper airway during sleep. • May be associated with arousal from sleep &/or decrease in O2 saturation • Serious life threatening • 8yr mortality rate 40% • Underdiagnosed

  3. Type of disordered breathing event • Central An event with absence of airflow with no respiratory effort • Obstructive An event with absence of airflow but with continued respiratory effort • Mixed An event with characteristics of an obstructive & mixed event. Start with a period that meets the criteria for a central event but will end with respiratory effort without airflow

  4. Type of obstructive breathing event • OSA - Total cessation of airflow for 10sec or more despite continued ventilatory efforts - with O2 desaturation of 4% or more. • Obstructive sleep hypopnea -Decrease of 30-50% in airflow for 10 sec or longer with desaturation • Upper airway resistance - Snoring during sleep without frank apnea or hypopnea, does not result on desaturation

  5. Symptoms Nocturnal • Loud disruptive snoring* • Breathing pauses (apneas) • Sudden arousals with choking* • Nocturnal sweating Day time symptoms • Excessive daytime sleepiness* (falling asleep at work, when on telephone or whilst driving) • Unrefreshing sleep, morning headache (Co2, cerebral vasodilatation) • Fatigue, impaired concentration • Lethargy, Depression • Morning dry cough • Impotence, sexual dysfunction • Enuresis

  6. Pathophysiology Central sleep apnea • Uncommon • Physiological inhibition of breathing • Abnormal neurologic control of the diaphragm, resulting in the loss of respiratory drive Obstructive sleep apnea • > 10% over 65 yr • Men > women • Episodic collapse & blockage of the upper airway during sleep despite continuous respiratory effort

  7. Pathophysiology

  8. Pathophysiology • Airflow obstruction can occur from soft palate to the hypopharynx posterior to the tongue • Upper airway patency- muscle tone, tissue mass, tissue consistency • Pharyngeal transmural pressure- difference between the pressure within the airway lumen & the pressure exerted by tissue surrounding the site of collapse • Decrease in pharyngeal transmural pressure • Pharyngeal dilator muscle tone prevents upper airway collapse. It is decreased during stage 4 & REM sleep which leads to narrowing of airway with turbulent airflow & snoring.

  9. Causes of OSA • Obesity -deposition of adipose tissue within the muscles & soft tissues surrounding the upper airway & ex compression from the neck ↓ narrowing of the upper airway. -↓lung volume, restrictive pulmonary defects, V/Q mismatch & hypoventilation • Pickwickian syndrome- severe form of OSA, morbid obese with Rt. Heart failure • Macroglossia, enlarged tonsils ↓ further narrowing of the pharyngeal lumen, increases the likelihood of airway collapse during inspiration • Gravity – lateral position, by enlarging retropalatal & retroglossal aspect of the airway

  10. Contributing factors • Abnormalities in the autonomic control of the pharyngeal muscles - acts by changing the balance between forces promoting the patency & those favouring its collapse • ↑ vagal tone, nocturnal paroxysmal asystole, episodic bradycardia, sinus node dysfunction • Autonomic chemoraceptors reacting to hypoxia, hypercapnia & acidosis trigger an inflammatory cascade HTN, insulin resistance, atherosclerosis & metabolic syndrome • Estrogen protection • Hormonal imbalance- acromegaly, cushing syndrome, hypothyroidism, DM • Airway moisture & surface tension in the fluid lining the upper airway, alter the function of pharyngeal sensory receptors

  11. Risk factors • Obesity –BMI >30kg/m2 1. Fat deposition around the upper airway can decrease upper airway size. 2. Neck circumference greater than 16 inches in female or greater than 17 inches in males • Male, middle age, Race, • Family history, Alcohol consumption ( phargl msc tone) • Craniofacial abnormalities • Habitual snoring & gasping noted by bed partner • Daytime sleepiness • Hypertension • High mallampati score • Unexplained polycythemia, room air hypoxemia or signs of right sided heart failure.

  12. Acromegalic pt with & without OSA

  13. Other causes of daytime sleepiness • Sleep deprivation • Shift work • Depression • Narcolepsy • Hypothyroidism • Sedatives • Excessive alcohol • Idiopathic hypersomnolence • Neurological conditions: previous head injury, previous encephalitis, parkinsonism, dystrophica myotonica

  14. Indices on disordered breathing severity • Apnea-hypopnea index (AHI) (severity of OSA) no. of apnea & hypopneas per hr of total sleep time • Apnea index no. of apnea per hr of total sleep time • Hypopnea index no. of hypopneas per hr of total sleep time • Central apnea index no. of central apnea per hr of total sleep time • Arousal index - no. of arousal per hr of sleep • Body position, NREM & REM sleep

  15. Indices on disordered breathing severity • Mild: AHI – 5 - 14 events per hr • Moderate: AHI 15 – 30 events per hr • Severe : AHI> 30 per hr

  16. The stages of snoring Non REM sleep • High alertness to deep sleep. Stage 1 to 4 • Changing pattern of electrical activity in the brain • Skeletal muscle start to relax REM sleep • Brain activity looks similar to wakefulness • Absence of skeletal muscle tone so effectively paralysed Conventional snoring • Stage 3-4, later in 1 & 2 Sleep apnea • REM sleep

  17. Diagnosis • A sleep study or a polysomnogram -Standard test for OSA - Identifying abnormal or disordered breathing pattern during sleep • Simultaneous recording of multiple physiological signals rt. & lt. electro-oculograms submental electromyogram electroencephalogram • Distinguish wakefulness from sleep & determine the distribution of different sleep stages over the course of the night

  18. Diagnosis • Impedance plethysmography to assess breathing patterns with measurements of respiratory efforts • Airflow – oronasal thermistor (temp change) or a nasal cannula (pressure changes) • Oxygen saturation • Body position • electrocardiogram – arrhythmias • Epworth sleepiness scale (ESS) max – 24 best available tool to guide the clinician as to the pt’s perception of his sleepiness normal < 11 mild subjective daytime sleepiness 11-14 mod subjective daytime sleepiness 15-18 severe subjective daytime sleepiness >18

  19. Polysomnogram (normal)

  20. Polysomnogram (OSA)

  21. Polysomnogram (central)

  22. Polysomnogram (mixed)

  23. OSA

  24. Obstructive hypopnea

  25. Upper airway resistance

  26. Comorbidities • Hypertension • Obesity • Diabetes mellitus • Coronary artery disease • Cerebral vascular disease & stroke • Congestive heart failure • Cardiac dysrhythmias • Gastroesophageal reflux disease

  27. Cardiovascular ↑sympathetic tone systemic HTN pulmonary HTN polycythemia art. hypoxemia art. hypercarbia rt. heart failure lt. heart failure stroke arrhythmia myocardial ischemia Cognitive hypersomnolence personality changes cognitive deficits accident prone Pathophysiological consequences

  28. Treatment • AHI >15, • More than ten 4% desaturation/hr 1.Behavioural interventions 2.Nonsurgical 3.Surgical

  29. Behavioural interventions • To lose wt. • life modifications • Stop smoking • No alcohol esp in the evening • No sedatives • Discourage from sleeping on their back by using Triangular pillow – space for the pt’s arm under the head to encourage sleeping on the side

  30. Nonsurgical management The American Academy of Sleep Medicine guidelines recommend • Continuous positive airway pressure CPAP AI > 20, symptomatic pt with AHI > 10 • Function as a mechanical stent to maintain upper airway patency th. out all phases of sleep breathing • Nasal CPAP- proper use eliminates excessive day time sleepiness, reduce HTN, improve neurocognitive function • Increased augmentation of lung volume • Increase in the tone of the upper airway • Improved LVF • Reduce morbidity in pt with CHF • Reduction in the sympathetic tone

  31. Nonsurgical management • Nasal CPAP highly effective & acceptable in 72-91% • Bulky, noisy, difficult to bring on trips & require electricity • Pts who sleeps in lt position knock the mask off. • Intolerance by the pt’s partner • Claustrophobia, nasal congestion, chest discomfort & inconvenience Bilevel positive airway pressure (bilevel PAP) • Improved pt comfort, tolerance • Provide ventilatory assistance for pts who require high CPAP(COPD)

  32. Nonsurgical management Adjustable oral appliances To enlarge the airway by keeping the tongue in an ant position or displacing the mandible forward (jaw thrust technique) 1.Mandibular repositioning devices (MRD) • snoring or mild to mod OSA, unable to tolerate CPAP • High compliance (50-75%) • Xerostomia, dental pain,temporomandibular joint pain, excessive salivation & changes on occlusion 2. Drugs • Protriptyline, acetazolamide, progesterone, theophylline • Modafanil • Fluoxetine 3. Nocturnal O2 therapy • Severe arterial desaturation

  33. Surgical management Aim : • relieving site-specific problems in the upper airway • increasing pharyngeal caliber & reducing pharyngeal resistance during sleep Complete evaluation: • recent polysomnogram, • head & neck exam (flexible nasopharyngeal fiberoptic exam), • assessment of disproportionate anatomy (elongated soft palate, thickened uvula, large base of tongue, DNS,enlarged tonsils, hypertrophic nasal turbinates & hypoplastic or retrognatic mandible), • imaging studies (cephalometrics or CT scan)

  34. Surgical management 1.Uvulopharyngopalatoplasty (UPPP) 2. Tonsillectomy 3. Nasal sx 4. Tracheostomy 5. Jaw advancement techniques 6. Minimally invasive techniques • Genioglossus advancement • Multilevel radiofrequency tissue ablation • Tongue-base suspension • Future research - Muscle strengthening with transcutaneous neuromuscular stimulation

  35. Preoperative assessment Identifying pts – questions for exploring • Do people tell you that you snore? • Do you wake up at night with a feeling of shortness of breath or choking? • Do people tell you that you that gasp, choke or snore while sleeping? • Do you awake feeling almost as or more tired than when you went to bed? • Do you often awake with a headache? • Do you often have difficulty breathing through your nose? • Do you fight sleepiness during day time? • Do you fall asleep when relaxing after meals? • Do other comment on your sleepiness during the day?

  36. Pre anesthetic visit • Weight & height • Neck circumference • Abnormally small size mandible • Nasal patency • Upper airway for obvious obstruction (IL) • Tongue (macroglossia), dentition • Pharynx (tonsillar size, uvula, lumen size) • BP • RS, CVS, CNS ex • FEV1, FVC • Hypothyroidism, acromegaly, Marfan’s syndrome

  37. Next step Nonurgent procedure • Evaluation by a sleep specialist • Primary treatment. • Milder – conservative • Mod to severe - initiation of CPAP therapy Advantages • improvement in some cardiovascular squeal within several wks of initiation of therapy • 4-6wks - ↓tongue volume & ↑ pharyngeal tone • reduce the risks of difficult airway management • perioperative respiratory embarrassment • improve cardiovascular function

  38. Approach to guide anesthetic management • Management of the airway should be conservative, with measures taken to minimize hypoxia secondary to airway obstruction or apnea • Cautious, titrated administration of sedatives, monitoring & observation of pt. • Adequate preoxygenation if plan is to ablate spontaneous ventilation • LMA & emergency airway devices s/b immediately avilable. • Regional anesthesia with careful sedation

  39. Approach to guide anesthetic management • Maintenance of general anesthesia s/b with the use of newer, shorter acting drugs to minimize the duration of postoperative ventilatory depression. • Extubation – in difficult airway, in conservative fashion, pt. strength & level of consciousness • Adequate postoperative analgesia • NSAIDS, local anesthetics for incision infiltration, epidural analgesia, peripheral nerve blocks • Minimize administration of large dose of narcotics

  40. Anesthesia technique • Regional anesthesia - min affecting resp drive - maintain arousal response during apneic episode • Sedation must be carefully administered & monitored, it will worsen hypoventilation • General anesthesia with regional anestheisa allow rapid restoration of consciousness • Outcome depends on type of sx. • Neuraxial opioid have been ass with unexpected degree of ventilatory depression

  41. Anesthetic management • Anesthetic drugs profoundly influence control of the respiratory system, which is already dysfunctional • Exaggerated responses • Thiopentone, propofol, opioids, benzodiazepines & nitrous oxide- reduce the tone of the pharyngeal musculature that acts to maintain airway patency. • Response to Co2 in children with OSA & tonsillar hypertrophy is diminished • Depressed ventilation – 50% apnea after 0.5µg/kg of fentanyl • Shorter acting drugs

  42. Rapid sequence induction To reduce the risk of pulmonary aspiration • Pharmacological agent with or without gastric suctioning • Reduce gastric volume & acidity • Rapid acting hypnotic agent & MR to limit apneic time & providing non hypoxemic apneic period • Absence of mask ventilation after a preoxygenation – FRC is reduced → faster desaturation → safe apneic pr. is reduced from >5min to < 2-3min. • Absence of mask ventilation → atelectasis. Constant CPAP during preoxygenation & gentle ventilation with PEEP during induction significantly reduce atelectasis

  43. Rapid sequence induction Cricoid pressure – correct application • Initiate with a forceof 20N as the induction started & to increase the force to 30N as loss of consciousness occurs • Adversely affect mask ventilation (directly posterior with gradual release) • Adversely affect laryngoscopy view (backward & upward laryngeal displacement) • More difficult LMA insertion • Less successful intubating LMA • Trendelenburg position, suction available & graded release of cricoid pressure

  44. Rapid sequence induction Difficult airway • Sp. Alteration in airway anatomy & physiology – difficult mask ventilation & intubation • Diabetes mellitus (limited jt mobility syndrome) • paramount concern - Ability to assure oxygenation & ventilation • Secondary concern – difficult airway & inadequate anesthetic depth during difficult airway management

  45. Muscle relaxant Succinylcholine • 0.6mg/kg • Fasciculation – rise in gastric pressure (40mmHg) • Rapid onset & short duration of action • Rapid return of spontaneous ventilation Rocuronium • Faster onset • Longer duration – not for pts with difficult airway • Less side effects

  46. Intraoperative monitoring • According to type of sx, comorbidities • TEE – ventricular filling & function • Intra-arterial catheter to monitor blood pressure • Metabolic alkalosis can result in mild hypoventilation. Maintenance of baseline bicarbonate

  47. Extubation • Challenging • Deep extubation – occasionally practiced • Fully conscious • Intact upper airway reflexes • Adequate muscle strength • In the OT or in ICU with facility for reintubation • Difficult intubation cart • Noninvasive mechanical ventilation immediately after extubation

  48. Postoperative consideration Immediate: PACU • Most complications – first 2hr • continuous monitoring, depending on I/O complications • frequent assessment of s/s of airway problems • 1 in 500 pt will require reintubation • Difficult intubation • Continuous O2 thr. Face mask or nasal CPAP (if nasogastric tube in place then seal of nasal CPAP is not adequate) • Posture & positioning – HOB 300 (↑ stability of the upper airway) • Adequate blood pressure control – HTN due to pain, hypercarbia, anxiety. VASOTRAC device for BP monitoring

  49. Postoperative consideration Disposition from PACU • Preop AHI, CPAP dependence • RVF, LVF, Lung disease, Degree of obesity, Nature of sx • Mild OSA & min comorbidities for minor sx ↓ discharge on the day of sx • Mod OSA & intermediate comorbidities for interm.risk sx ↓ admission to a standard M or Sx unit • Severe OSA with CPAP at home & multiple comorbidities ↓ closer observation on ICU or intermediate care unit depending on the nature of the sx

  50. Perioperative issues for OSA sx • Max with in 2hrs of sx • Airway obstruction, laryngospasm, desaturation & postop pul oedema • Postop. Hemorrhage • HTN

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