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Down’s syndrome

Down’s syndrome
Brendan Carvalho
Down’s syndrome (trisomy 21) is the commonest congenital abnormality, with an incidence of 1.6 per 1000 births. Anaesthesia and surgery carry a higher morbidity and mortality than in the general population.
General considerations
In addition to the characteristic dysmorphic features and impaired global development, Down’s syndrome is associated with disorders of many organ systems:
  • Congenital cardiac defects (in up to 40%)—predominantly endocardial cushion defects and ventricular septal defects.
  • Eisenmenger’s syndrome (pulmonary hypertension with right-to-left shunt) may complicate the perioperative management of the older child particularly if there is associated obstructive sleep apnoea.
  • Recurrent respiratory tract infection due to relative immune deficiency and a degree of upper airway obstruction (tonsillar/adenoidal hypertrophy).
  • Atlantoaxial instability (in up to 30% of individuals)—subluxation/dislocation tendency due to bony abnormality of the atlas and axis and laxity of the transverse atlantal ligament.
  • Epilepsy (in up to 10% of individuals).
  • Obesity and potentially difficult venous access.
Preoperative assessment
  • Careful airway assessment for potential difficult airway maintenance and intubation (relatively large tongue, crowding of midfacial structures, high arched narrow palate, micrognathia, short broad neck).
  • Cardiorespiratory assessment for signs and symptoms of congenital cardiac defects, pulmonary hypertension, and chest infections.
  • Symptoms of atlantoaxial instability (abnormal gait, clumsiness, hyperreflexia, clonus, hemi/quadriparesis, extensor plantars, neurogenic bladder, ataxia, and sensory loss), although atlantoaxial instability is frequently asymptomatic.
Investigations
Patients have usually been fully investigated by the paediatric team:
  • Full blood count (incidence of polycythaemia and leukaemia is 20 times that seen in the general population). Urea and electrolytes and thyroid function tests (hypothyroidism in up to 40%).
    Preoperative investigations as per clinical findings and surgical procedure planned:
  • ECG as routine.
  • Chest radiograph if there are cardiorespiratory problems.
  • Echocardiography if signs or symptoms are suspicious of a cardiac defect.
  • Lateral cervical spine radiographs are indicated only if there are neurological signs or symptoms, and current opinion would suggest that routine screening is inappropriate.

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Preparation
  • Optimize cardiac and respiratory function.
  • Reduced threshold for arranging HDU/ICU for postoperative care due to the high incidence of perioperative complications.
  • Patients are often uncooperative and a sedative premedication to prevent struggling during induction is often helpful, e.g. oral midazolam (0.5 mg/ kg) or temazepam (0.5 mg/kg) in the older age group. Exercise caution if problems with airway obstruction exist.
  • Establish rapport with parents and carers.
  • EMLA/Ametop cream should be applied if intravenous induction is planned.
  • Inhalational induction with sevoflurane/halothane is useful, especially in uncooperative patients with difficult intravenous access. IM ketamine (5–10 mg/kg) is also an option.
  • Drying agents may be useful if hypersalivation is problematic. Caution should be exercised when giving atropine as exaggerated sensitivity to both mydriatic and cardiac effects have been reported. Consider a reduced dosage or using an alternative agents, e.g. glycopyrrolate.
  • There is a high incidence of gastro-oesophageal reflux. Give reflux prophylaxis (ranitidine) if symptomatic.
Perioperative considerations
  • Potential difficult airway maintenance and intubation.
  • Take care to avoid excessive movements of the neck, especially during laryngoscopy and positioning for surgery.
  • There is increased incidence of subglottic stenosis in children with Down’s syndrome—a smaller tracheal tube than would have been predicted by age is frequently required.
  • No abnormal responses to anesthetic drugs have been substantiated.
  • Prone to hypoventilation—IPPV often preferable to spontaneous ventilation.
  • Prophylactic antibiotics for cardiac defects should be given prior to predictable bacteraemic events.
  • Strict asepsis-relative immune deficiency and increased susceptibility to infections.
  • Universal precautions—increased incidence of hepatitis B and C.
  • Postoperative pain management may be problematic. Consider regional blocks wherever possible. PCA can be used successfully in appropriate patients.
Postoperative considerations
  • Patients who are compromised and those undergoing major surgery should be managed on HDU/ICU postoperatively.
  • Parents/carers are indispensable in the recovery period as Down’s syndrome patients are often agitated postoperatively and may be very difficult to manage.

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  • Associated hypotonia (up to 75%) may affect the ability to maintain an adequate airway following anaesthesia and patients should be carefully observed.
  • Patients are prone to atelectasis and respiratory tract infections especially following abdominal and thoracic surgery-humidified oxygen, regular physiotherapy, adequate analgesia, and close monitoring are required.
  • The duration of postoperative ventilation, intensive care, and hospital stay all tend to be longer than the general population.
Further reading
Mitchell V, Howard R, Facer E (1995). Clinical review: Down’s syndrome and anaesthesia. Paediatric Anaesthesia, 5, 379–84.

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