Obstructive sleep apnoea

OBSTRUCTIVE
SLEEP APNOEA
AND
ANAESTHESIA
BY
Dr. Chamika Huruggamuwa
Registrar in Anaesthesiology
TH KANDY

• OBSTRUCTIVE SLEEP APNOEA (OSA) is a sleep-related breathing disorder
characterized by repeated episodes of Apnoea and Hypopnoea during sleep.
• SLEEP DISORDERED BREATHING IN CHILDREN
• SDB in children encompasses primary snoring, upper airway resistance syndrome,
obstructive hypopnoea and obstructive sleep apnoea

• Primary snoring is defined as noisy breathing during sleep without desaturation or
obstructive episodes and without daytime symptoms.
• Upper airways resistance syndrome (UARS) is defined as snoring associated with
sleep disruption and arousal, with daytime symptoms but no abnormalities of gas
exchange at night.
• Obstructive hypoventilation (OH) occurs when upper airways resistance is increased
sufficient to cause paradoxical ventilation (loss of synchrony between thoracic and
abdominal movements), with desaturation and or carbon dioxide retention.
• Obstructive sleep apnoea (OSA) is the most severe form of SDB when children
demonstrate cessation of nasal/oral airflow during sleep with preserved thoracic and
abdominal respiratory effort and oxygen desaturation

• Apnoea -Complete cessation of airflow for more than 10 seconds
• Hypopnoea - Airflow reduction more than 50% for more than 10 seconds.

‘OSA syndrome’
• Clinical entity of OSA resulting in
• Excessive daytime sleepiness
• Other symptoms such as unrefreshing sleep, poor concentration, fatigue and
morning headaches.

EPIDEMIOLOGY
• In middle age, the prevalence of overt OSA is approximately 4% in men and
2% in women
• It is estimated that 80% of patients are undiagnosed, with sleep study data
estimating sleep disordered breathing having a prevalence of 24% in men
and 9% in women.

• OSA is strongly correlated with obesity, in particular morbid obesity (Body
mass index >40 kg/m2, or a BMI >35 kg/m2 with significant co-
morbidities).
• It is found in 40% of obese females and 50% of obese males.

The most common aetiology of SDB in
children is
• Adenotonsillar hypertrophy.
• chromosomal abnormalities such as Downs syndrome
• craniofacial abnormalities associated with severe mid-face hypoplasia such as Aperts
or Crouzons syndrome; Treacher-Collins or Pierre Robin sequence
• (micrognathia); cerebral palsy (hypotonia); sickle cell disease (lymphoid hyperplasia);
papillomatosis,
• cystic hygroma (foreign body).
• Obesity is becoming an increasingly common cause of OSA in older children

PATHOPHYSIOLOGY
• The body is in its most relaxed state during REM sleep,
Tone of the pharyngeal dilator muscles
(musculus genioglossus and musculus geniohyoideus)
Pharyngeal Airways Collapse - Airway obstruction
Inspiratory efforts increase
Negative pressures produced by the diaphragm and intercostal muscles promote a collapse of the
oropharynx

With airway obstruction,
Inspiratory efforts increase as arterial oxygen desaturation
Partial arousal from sleep and a sudden opening of the airway.
A short period of hyperventilation follows, until sleep deepens
and airway obstruction recurs,
Repeating the cycle.
The result is blood gas oscillation and sleep fragmentation

In obese patients,
• increased adipose tissue in the neck and pharyngeal tissues narrows the
airway further, predisposing to airway closure during sleep.
In non-obese patients,
• Tonsillar hypertrophy or craniofacial skeletal abnormalities may lead to
airway narrowing and sleep apnoea.

OSA In Pregnancy
• During pregnancy, intermittent SDB occurs in more than 50% of women.
Snoring and OSA are independently linked to hypertension in pregnancy.
• CPAP therapy has been demonstrated to be a safe and acceptable adjunct for
blood pressure management in the group of women with OSA and
associated hypertension.
• Some reports have associated fetal growth retardation with OSA

Physiological changes Arising from repetitive
airway obstruction
• Arterial hypoxaemia,
• Arterial hypercarbia,
• polycythaemia,
• systemic hypertension,
• pulmonary hypertension,
• cardiac rhythm disturbances and
• Right ventricular failure.
• There is an increased incidence of heart disease, cerebrovascular events and sudden death.

Children with OSA have
• Failure to thrive, .
• possibly due to reduced caloric intake, increased work of breathing
at night, or reduced secretion of growth hormone
• CNS complications
• Learning and behavioural problems as a consequence of sleep disturbance.
• There is some evidence that the CNS complications may be related to an
inflammatory response secondary to repeated nocturnal hypoxia.

• Cardiovascular complications.
• Severe OSA with repeated nocturnal hypoxia is associated with pulmonary
hypertension
• may result in right heart failure.

Diagnosis of OSA
• History and Examination
• Predisposing conditions combined with a
• history of snoring,
• restless sleep,
• headaches,
• and daytime sleepiness should alert to the possibility of OSAS

Polysomnography (psg)
PSG examinations include
Recordings of heart rhythm (ECG),
Electroencephalography (EEG),
Blood pressure,
Eye movements,
Electromyography.
Snoring volume,
Oro-nasal airflow,
Peripheral pulse oximetry
are usually also recorded.

The Apnoea/Hypopnoea Index (AHI)
• Number of Apnoea and Hypopnoea periods lasting 10 s or longer per hour
of sleep
The American Academy of Sleep Medicine
• definitions of Hypopnoea to include
• (i) 30% airflow reduction and 4% desaturation or
• (ii) 50% reduction in nasal pressure signal excursions with associated 3%
desaturation or arousal, respectively

• AHI > 5 mild
• > 15 moderate OSA
• >30 severe

RISKS ASSOCIATED WITH
ANAESTHESIA
• OSA is associated with increased peri-operative morbidity and mortality.
• The peri-operative risk increases in proportion to the severity of OSA.
Sedation, Analgesia or Anaesthesia
potential loss of the airway caused by the use of anaesthetic, sedative and opioid drugs
• Difficult intubation and postoperative respiratory depression and airway obstruction
are also possible.

PREOPERATIVE MANAGEMENT
• Preoperative Screening STOP-Bang model
• signs of cardiomegaly -CXR. may demonstrate prominent central pulmonary arteries.
An ECG reveals signs of right ventricular hypertrophy (right axis deviation, peaked P
waves, tall R waves in lead V1).
• Echocardiography confirms the diagnosis of
• Pulmonary hypertension, Right ventricular hypertrophy +/- dilatation.
• Adenotonsillar hypertrophy may contribute in part to OSA and these children may
benefit from tonsillectomy.

Preoperative treatment
• The gold standard of treatment for OSA is the nocturnal use of nasal
continuous positive airway pressure (nCPAP) delivery devices.

• A nasal mask provides positive airway pressure
• Pressure requirements range from 5 to 20 cmH2O, depending on the severity
of the obstruction.
• Preoperative use of nasal CPAP may lead to improvement in condition prior
to surgery and better postoperative compliance with the device.

• Mandibular advancement devices may be used for mild OSA. These
devices position the mandible forward, pulling the tongue away from the
posterior pharyngeal wall.

• Uvulopalatopharyngoplasty is no longer performed for the surgical
management of OSA.
• Preoperative weight loss can also be recommended.

Preoperative planning
• Elective surgery should be postponed until the patient has been fully
investigated and treated.
• Review of previous anaesthetic notes grading ease of direct laryngoscopy
and intubation should be sought.

INTRAOPERATIVE MANAGEMENT
• Premedication
• BDZs as premedication relaxes upper airway musculature, reducing the
pharyngeal space
• hypopnoea, and consequently hypoxia and hypercapnia preoperatively.
• Ideally all sedative premedications should be avoided, or used extremely
cautiously.

Choice of Anaesthetic Technique
• Local or Regional Anaesthesia is preferred mode of anaesthesia.
• General anaesthesia with a secured airway is preferred to deep sedation without a secure
airway.
• Intraoperative CPAP may be helpful.
• Common anaesthetic drugs that have been shown to cause pharyngeal collapse include
• propofol, TPS, opioids, BDZ, NMB and N2O

Intubation technique
• OSA Difficult intubation.
• Cormack laryngoscopy grade III and IV views in 90% of patients with OSA

• Equipment necessary to handle a difficult airway should be readily available prior to
induction,
• Adequate preoxygenation
• Laryngoscopy optimal ‘sniff’ position.
• Awake fibreoptic intubation should be made if an airway problem is suspected..
• Adverse effects associated with difficult airway management include death, brain
injury, cardiorespiratory arrest, airway trauma and damage to teeth.

• Children with severe OSA have increased opioid sensitivity and have been
estimated to require 50% less opioid than normal children
• This is postulated to be due to up-regulation of μ opioid receptors
• Simple analgesics should be used (and for general
• surgical procedures in children with OSA, regional blocks);
• opioid analgesia should be kept to a minimum in the postoperative period.

Extubation
• The patient conscious, communicative, and breathing spontaneously with an
adequate tidal volume and oxygenation.
• semi-upright or lateral position, after complete reversal of neuromuscular
blockade.

• OSA was independently associated with significantly increased odds of
emergent intubation and mechanical ventilation, NIV, respiratory failure, and
atrial fibrillation
• Mokhlesi B, Hovda MD, Vekhter B, Arora VM, Chung F, Meltzer DO. Sleep-
disordered breathing and postoperative outcomes after elective surgery: analysis of the
nationwide inpatient sample. Chest 2013;144:903–14

POSTOPERATIVE MANAGEMENT
• Respiratory depression and repetitive apnoeas are common immediately following
extubation.
• Supplemental oxygen should be administered continuously to all OSA patients until they
are able to maintain their baseline oxygen saturation whilst breathing room air.
• The ASA recommend OSA patients should be monitored for three hours longer than
usual before being discharged from a facility.
• Oxygen administration will not prevent apnoea
Reduce the duration of apnoea and the degree of resulting oxygen desaturation.
• postoperative nasal continuous airway pressure

• Upper airway surgery - prolonged period of tracheal intubation
postoperatively, in view of the potential for significant airway swelling
• HDU/ICU care
• Adequate pain relief remains a priority in OSA
• Non opioid analgesics –PCM,Tramadol,clonidine,ketamine,NSAIDS.
• Regional nerve blocks

• Day-case surgery and OSA???

• Sufferers of OSA, due to their fragmented poor quality sleep, are a potential
danger to themselves and to others who may be dependent upon their
judgement and vigilance,,,,,,,,……
• awareness of the potential of OSA in ourselves must be considered if we are
to perform our anaesthetic duties without endangering the lives of our
patients.

Obstructive sleep apnoea

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