Apnoea

Published on 03/06/2015 by admin

Filed under Neonatal - Perinatal Medicine

Last modified 22/04/2025

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CHAPTER 20 Apnoea

David Cartwright, Mark Davies

Background

Definition:

• either 20 seconds of zero flow in or out of the lungs; or
• 10 seconds of zero flow accompanied by desaturation or bradycardia.

An episode of apnoea may or may not be accompanied by bradycardia and cyanosis.

Causes of apnoea in newborns:

• infection — meningitis, septicaemia, pneumonia, necrotising enterocolitis, viral upper respiratory tract infection (especially respiratory syncytial virus, RSV)
• hypoxia
• acidosis
• seizures
• metabolic disturbances — hypoglycaemia, hyponatraemia, hypocalcaemia
• intraventricular haemorrhage
• airway obstruction
• gastric or abdominal distension
• gastro-oesophageal reflux, including lowered pH in mid-oesophagus
• apnoea of prematurity (many of the above may contribute to this).

Consequences of apnoea:

• hypoxia / acidosis
• progressive atelectasis
• gastro-oesophageal reflux
• aspiration.

Investigations may include:

• blood sugar level (BSL), arterial blood gas (ABG), urea and electrolytes (U&Es), calcium, magnesium, blood culture, full blood count (FBC) and film examination
• chest X-ray
• lumbar puncture
• cranial ultrasound examination.

Apnoea of prematurity

• Apnoea occurs because of brain-stem immaturity in babies less than about 34 weeks gestational age.

— The apnoea is worse the more immature the baby.
— Apnoea usually starts after 2 days of age.

• Bradycardia and hypotonia may accompany apnoea, or occur independently in the same infant.
• Apnoeic episodes are more common during rapid eye movement (REM) sleep.

— At 32 weeks gestational age, babies sleep about 18 hr/day, of which 80% is REM sleep.
— At 3 months of age, they sleep about 14 hr/day, of which 40% is REM sleep.

• Apnoea is more common the higher the environmental temperature, and during feeding or defaecating.
• Any baby with increasing severity or frequency of apnoea must be considered infected, and covered with antibiotics, until proven otherwise (seeCh 17).

Management of apnoea

Preventive:

• Prevent hypoxia/acidosis, fluctuations in oxygen requirement, reflux or aspiration.
• Feed slowly, give small volumes, avoid gastric or abdominal distension; prone positioning may help.

Treatment:

• Stimulate early.
• Monitor.
• Drugs:

— theophylline/aminophylline (see page 80)
— caffeine (see page 80)
— doxapram may be added to methylxanthines, but must be given by continuous infusion.

• Mechanical treatment — continuous positive airway pressure (CPAP), ventilation.

Response to theophylline:

• 15% respond at serum level of 4.2 mg/L
• 30% respond at serum level of 8.5 mg/L
• 75% respond at serum level of 12.7 mg/L
• 80% respond at serum level of 15.3 mg/L.

However, there is no need to routinely measure the theophylline level. Both effectiveness and toxicity are very obvious clinically:

1. If a baby’s apnoea is controlled on a standard dose and they are not tachycardic, then the baby is either receiving adequate drug or doesn’t need any.
2. If a baby is persistently tachycardic on theophylline, then they are toxic by definition, whatever the serum theophylline level might be.
3. If a baby’s apnoea is not controlled on a standard dose of theophylline, a serum level may help you to determine whether the drug is not being adequately absorbed, or if the baby is a ‘non-responder’.

Theophylline is usually ceased after 34 weeks gestational age if there is no apnoea. Monitoring for apnoea should continue for a few days after ceasing theophylline.

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