Sleep Apnea Syndrome

Question 1

Definition and symptoms

Answer 1

Sleep apnoea : is defined as cessation of airflow at the mouth and nose for at least 10s.
Sufferers develop intermittent respiratory arrest and hypoxaemia during rapid eye movement (REM) sleep. Respiration resumes due to hypoxic stimulation.

• the majority of sufferers are overweight, middle-aged men, who present with complaints of snoring with periods of apnoea, disturbed sleep, excessive daytime drowsiness, and headache.

Question 2

Types of Sleep Apnea Syndrome

Answer 2

two types of sleep apnoea are recognized:
•OSA (85%). this results from obstruction of the upperairway

• Central apnoea (5%). this is due to intermittent loss of respiratorydrive.
• Five per cent of patients have bothtypes.

Question 3

Dx pf Sleep Apnea and treatment

Answer 3

• the condition can often be diagnosed using history and examination alone, but, for standardization and a qualitative diagnosis, more formal investigations are required. Asleep study with polysomnography (PSg) will establish the extent and severity of OSA.

PSg examinations include recordings of ECg, electroencephalography (EEg), eye movements, and electromyography. Snoring volume, oronasal airflow, and peripheral pulse oximetry are usually also recorded.

• the two most widely available treatment options for OSA include weight loss andCPAP.

Question 4

General considerations ( Risks)

Answer 4

• there is an increased perioperative risk in OSA patients. this is likely due to increased upper airway collapse and OSA-related co-morbidities.
• OSA is an independent risk factor for serious neurocognitive, endocrine, and CVS morbidity and mortality in all age groups. For example, OSA patients are at increased risk of cerebrovascular accidents, depression, psychosocial problems, impaired glucose tolerance, dyslipidaemia, hypertension, and arrhythmias.
• Biventricular dysfunction, pulmonary hypertension, and CCF significantly increase the risk of haemodynamic instability in the perioperative period.
• In children, OSA is most commonly associated with adenotonsillar hypertrophy, but the severity of OSA is not always proportional to the size of the tonsils and adenoids.
• Patients with sleep apnoea syndrome are at risk of perioperative airway obstruction and respiratory failure, while under the effects of sedativedrugs.

Question 5

Preoperative assessment

Answer 5

• OSA is undiagnosed in ~80% of patients. Preoperative evaluation should include a review of previous medical records, a history from the patient and/or family, and a physical examination.
• Check for airway difficulty with previous anaesthetics, hypertension, or other CVS problems. Ask about snoring, apnoeic episodes, disturbed sleep, morning headaches, and daytime somnolent
• Several screening tools have been developed and validated to identify potential surgical patients with OSA:the Berlin questionnaire, the ASA checklist, and the StOP-Bang questionnaire
• Ideally, patients with OSA should be risk-stratified to assess whether PSg (an expensive resource, which is often scarce and often has long waiting times) is required to assess severity, whether they are suitable for day-case surgery, and whether they require high dependency care post-operatively.
• Factors to take into consideration when assessing the level of risk in these patients include patient and surgical factors and the perioperative sedationrisk.
• Patient factors include the severity of OSA, presence of craniofacial abnormalities, compliance with CPAP, and obesity.
• Surgical factors include the site and duration of surgery, whether it can be performed laparoscopically, and whether it can be done using a regional anaesthetic technique.
• High perioperative sedation risk includes patients who are likely to require high doses of opioids in the perioperative period.
• Among preoperative patients in whom it is determined that diagnostic evaluation for OSA is warranted, clinicians need to decide whether to defer surgery until after a formal sleep evaluation or to manage the patient presumptively.
• Early liaison with the surgical team, respiratory physicians, and intensive care is important in high-risk patients.
• Aperiod of preoperative CPAP may be beneficial, particularly in high-risk patients.
• OSA should be considered in all children presenting for adenotonsillectomy.
• Ensure that management of associated conditions, such as obstructive airway disease, hypertension, and cardiac failure, is optimal.
• Ask patients to bring their own CPAP machine and mask for post-operative use. Ensure that ward staff are familiar with the set-up and running of equipment.

Question 6

Investigations

Answer 6

• In known OSA, perform FBC (polycythaemia), pulse oximetry, and ECg (right heart strain).
• If ECg shows RV strain (3% of children presenting for adenotonsillectomy), echocardiography is indicated to exclude RV hypertrophy.
• Obtain baselineABgs.
• Consider referral for PSg in high-risk patients

Question 7

Conduct of Anaesthesia

Answer 7

• If the patient is on inhalers, change to nebulized bronchodilators.
• Avoid night sedation or sedative premedication, as patients with OSA are susceptible to the central respiratory effects of benzodiazepines, opioids, and neuroleptics. Also, by enhancing the relaxation of the pharyngeal muscles during sleep, these drugs compound the symptoms ofOSA.
• Anticipate that mask ventilation and intubation may be difficult, and prepare forthis.
• Regional anaesthesia/analgesia and post-operative analgesia will avoid or minimize the use of gA agents and sedative opioid analgesics. Reduce doses of all sedative/anaesthesia drugs. Use short-acting anaesthetic/ analgesic agents where post-operative pain is minimal.
• gA, preceded by preoxygenation, with tracheal intubation and mechanical ventilation is preferred to sedation or a gA with spontaneous ventilation(SV). • give nSAIDs and paracetamol.

Question 8

Postoperative Care

Answer 8

• Ensure nMB is fully reversed, and extubate fully awake in the sitting position.
• nurse sitting up whenever possible.
• High-risk patients may require admission to HDU/ICU. Afew hours of post-operative ventilation may be required after major surgery.
• Administer supplementary O2, and ensure continuous pulse oximetry monitoring on theward.
• Unless contraindicated by the surgical procedure, CPAP should be administered continuously to patients who were using it preoperatively. Compliance may be improved if patients bring their own equipment into hospital.
• Aim to maintain the O2 saturation that the patient had preoperatively, titrating O2 to the minimum required. Afew patients may develop CO2 retention with O2 therapy. Serial blood gas analysis may be necessary in drowsy patients at risk of CO2 retention

Question 9

Stop-Bang questionare

Answer 9

Snoring ?
Do you Snore Loudly (loud enough to be heard through closed doors or your bed-partner elbows you for snoring at night)?

Tired ?
Do you often feel Tired, Fatigued, or Sleepy during the daytime (such as falling asleep during driving or talking to someone)?

Observed ?
Has anyone Observed you Stop Breathing or Choking/Gasping during your sleep ?

Pressure ?
Do you have or are being treated for High Blood Pressure ?

Body Mass Index more than 35 kg/m2?

Body Mass Index Calculator
cm / kg inches / lb
Height: Weight:

Age older than 50 ?

Neck size large ? (Measured around Adams apple)
Is your shirt collar 16 inches / 40cm or larger?

Gender = Male ?

Question 10

Scoring of STOP-BANG

Answer 10

OSA - Low Risk : Yes to 0 - 2 questions

OSA - Intermediate Risk : Yes to 3 - 4 questions

OSA - High Risk : Yes to 5 - 8 questions
or Yes to 2 or more of 4 STOP questions + male gender
or Yes to 2 or more of 4 STOP questions + BMI > 35kg/m2
or Yes to 2 or more of 4 STOP questions + neck circumference 16 inches / 40cm