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Apnoea of Prematurity (AOP) is the cessation of breathing for 20 seconds or longer, or a shorter pause accompanied by bradycardia (heart rate below 100 beats per minute) or oxygen desaturation (SpO2 below 80–85%), occurring in preterm infants. It is one of the most common complications of prematurity, affecting virtually all infants born before 28 weeks gestation and approximately 50% of those born before 32 weeks. AOP results primarily from the immaturity of the central nervous system respiratory control centres in the brainstem, which have not yet developed sufficient sensitivity to carbon dioxide or adequate coordination of breathing effort with upper airway tone. AOP is classified into three types: central apnoea (no respiratory effort due to absent central drive), obstructive apnoea (respiratory effort is present but airway is blocked by poor muscle tone), and mixed apnoea (most common — begins as obstructive then becomes central). The primary pharmacological treatment is caffeine citrate, a methylxanthine that stimulates respiratory centres via adenosine receptor antagonism. A loading dose of 20 mg/kg caffeine citrate (equivalent to 10 mg/kg caffeine base) is followed by a daily maintenance dose of 10–20 mg/kg caffeine citrate. The landmark CAP (Caffeine for Apnea of Prematurity) trial demonstrated that caffeine not only reduces apnoea frequency but also reduces rates of bronchopulmonary dysplasia (BPD), cerebral palsy, cognitive impairment, and death. AOP typically resolves by 36–44 weeks post-menstrual age (PMA), though some extremely preterm infants may require treatment beyond discharge.
AOP definition: apnoea ≥20 seconds, OR apnoea of any duration with bradycardia <100 bpm or SpO2 <80%; Caffeine citrate loading dose = 20 mg/kg IV/oral; Maintenance = 5–10 mg/kg/day IV/oral
- 1Confirm gestational age at birth — AOP risk is highest below 34 weeks and universal below 28 weeks gestation.
- 2Monitor all preterm infants continuously with cardiorespiratory monitoring (ECG and pulse oximetry) for apnoea, bradycardia, and desaturation events.
- 3Define and document apnoea events: record duration, presence of respiratory effort, associated bradycardia (HR <100 bpm) and desaturation (SpO2 <80%), and whether stimulation or bag-mask ventilation was required.
- 4Classify apnoea type: observe for respiratory effort on monitor; absent effort = central; effort present but no airflow = obstructive; both features = mixed.
- 5Initiate caffeine citrate: loading dose 20 mg/kg IV or orally (give over 30 minutes if IV); commence maintenance 24 hours later at 5–10 mg/kg/day.
- 6Optimise non-pharmacological measures: nursed prone or supine in neutral positioning; avoid neck flexion; consider nasal CPAP at 4–6 cmH2O for persistent or severe AOP.
- 7Plan discontinuation: cease caffeine citrate typically at 34–36 weeks PMA or after 5–7 apnoea-free days; observe for 5–7 days post-cessation before discharge in infants born <28 weeks.
Commence continuous positive airway pressure (CPAP) at 5 cmH2O as adjunct; expect clinical improvement within 24–48 hours
Loading dose = 20 mg/kg x 0.82 = 16.4 mg caffeine citrate IV over 30 minutes. Daily maintenance starts 24 hours later at 8.2 mg. Monitor caffeine levels if doses are modified.
Ensure CPAP pressure optimised; review for treatable secondary causes (anaemia, infection, reflux)
The single severe event requiring resuscitation warrants review. Caffeine dose increase within licensed range, plus investigation for secondary causes, is appropriate before escalating to mechanical ventilation.
Caffeine half-life in neonates is approximately 100 hours — therapeutic levels persist for several days after stopping
The long half-life means apnoea may recur 4–7 days after caffeine cessation. A post-cessation observation period is mandatory, especially in infants born below 28 weeks gestation.
Check FBC (anaemia), CRP (infection), blood glucose, electrolytes, cranial ultrasound
New or worsening apnoea in a previously stable preterm infant should prompt investigation for secondary causes: infection/sepsis, anaemia (Hb <10 g/dL requiring transfusion), intraventricular haemorrhage, metabolic disturbance, or gastro-oesophageal reflux.
Calculating caffeine citrate loading and maintenance doses for preterm infants in neonatal intensive care units.. This application is commonly used by professionals who need precise quantitative analysis to support decision-making, budgeting, and strategic planning in their respective fields
Timing decisions for caffeine discontinuation and discharge readiness in preterm infants.. Industry practitioners rely on this calculation to benchmark performance, compare alternatives, and ensure compliance with established standards and regulatory requirements
Monitoring and documenting apnoea events to assess treatment response and guide escalation decisions.. Academic researchers and students use this computation to validate theoretical models, complete coursework assignments, and develop deeper understanding of the underlying mathematical principles
Parent education about AOP, expected resolution timeline, and home safety before discharge.. Financial analysts and planners incorporate this calculation into their workflow to produce accurate forecasts, evaluate risk scenarios, and present data-driven recommendations to stakeholders
Quality improvement audits of time-to-caffeine initiation and apnoea event rates in NICUs.. This application is commonly used by professionals who need precise quantitative analysis to support decision-making, budgeting, and strategic planning in their respective fields
Anaemia-associated apnoea
{'title': 'Anaemia-associated apnoea', 'body': 'Anaemia reduces oxygen-carrying capacity, impairs tissue oxygenation, and worsens apnoea severity. Preterm infants with haemoglobin below 10 g/dL experiencing symptomatic apnoea are candidates for red blood cell transfusion, which frequently reduces apnoea frequency within 48 hours.'} When encountering this scenario in apnoea of prematurity calculations, users should verify that their input values fall within the expected range for the formula to produce meaningful results. Out-of-range inputs can lead to mathematically valid but practically meaningless outputs that do not reflect real-world conditions.
Gastro-oesophageal reflux and apnoea
{'title': 'Gastro-oesophageal reflux and apnoea', 'body': 'Despite a widely held clinical belief, the evidence linking GOR to AOP is weak. Most apnoea events in preterm infants are not temporally associated with reflux on multi-channel intraluminal impedance-pH studies. Anti-reflux medications such as ranitidine or omeprazole are not routinely recommended for AOP in the absence of proven GOR disease.'}
Severe AOP requiring ventilation
{'title': 'Severe AOP requiring ventilation', 'body': "Infants with frequent severe apnoea requiring repeated bag-mask ventilation or failing CPAP may need intubation and mechanical ventilation (typically with low-rate ventilation or high-flow nasal cannula oxygen). This represents a temporary measure while the infant's respiratory control matures."} In the context of apnoea of prematurity, this special case requires careful interpretation because standard assumptions may not hold. Users should cross-reference results with domain expertise and consider consulting additional references or tools to validate the output under these atypical conditions.
Caffeine toxicity
{'title': 'Caffeine toxicity', 'body': 'Signs of caffeine toxicity include tachycardia (HR >180 bpm), jitteriness, tremors, feeding intolerance, and, at very high levels, seizures. Therapeutic caffeine serum levels are 5–20 mg/L. Toxicity is unlikely at standard doses but may occur if the maintenance dose is erroneously calculated on total body weight without accounting for oedema.'}
| Gestational Age | Approximate AOP Prevalence | Typical Resolution PMA |
|---|---|---|
| <28 weeks | >95% | 38–44 weeks PMA |
| 28–31 weeks | ~75% | 36–38 weeks PMA |
| 32–33 weeks | ~50% | 34–36 weeks PMA |
| 34–36 weeks | ~15% | 35–37 weeks PMA |
| >37 weeks (term) | <1% (pathological cause likely) | Investigate secondary cause |
What is the difference between AOP and ALTE/BRUE?
AOP is specific to preterm infants before approximately 37–44 weeks post-menstrual age. ALTE (Apparent Life-Threatening Event) is an older term for events in term or older infants, now replaced by BRUE (Brief Resolved Unexplained Event) in infants over 60 weeks post-menstrual age. AOP is a physiological consequence of prematurity; BRUE requires investigation for a pathological cause.
How does caffeine treat apnoea?
Caffeine is a non-selective adenosine receptor antagonist. Adenosine normally inhibits respiratory drive in the brainstem. By blocking adenosine receptors, caffeine stimulates respiratory centres, increases sensitivity to CO2, and enhances respiratory muscle contractions. It also reduces fatigue of the diaphragm, making it effective against both central and obstructive components of AOP.
Is caffeine safe in preterm infants?
Yes. Caffeine citrate is one of the most evidence-based and well-tolerated drugs in neonatal medicine. The CAP trial (Lancet, 2006) demonstrated not only short-term efficacy but also long-term benefits at 18 months corrected age: lower rates of BPD, cerebral palsy, and developmental disability, with no evidence of harm at standard doses.
When should CPAP be used for AOP?
Nasal CPAP at 4–6 cmH2O is used for AOP that is predominantly obstructive or mixed, or when caffeine alone is insufficient (typically defined as more than 3–6 significant events per day requiring stimulation). CPAP splints the upper airway open, reducing the obstructive component of mixed apnoea. This applies across multiple contexts where apnoea of prematurity values need to be determined with precision.
Does AOP cause brain injury?
Intermittent hypoxia from AOP is associated with oxidative stress and may contribute to white matter injury and adverse neurodevelopmental outcomes. However, establishing causality is difficult because prematurity itself is a risk factor for brain injury. The CAP trial data suggest that treating AOP with caffeine reduces (but does not eliminate) neurodevelopmental morbidity.
What is post-menstrual age (PMA)?
Post-menstrual age (also called post-conceptional age) is calculated as gestational age at birth plus chronological age (in weeks) since birth. For example, an infant born at 26 weeks who is now 8 weeks old has a PMA of 34 weeks. PMA is used to track developmental milestones and to time clinical decisions such as caffeine discontinuation.
What happens if AOP persists beyond 36 weeks PMA?
Most AOP resolves by 36 weeks PMA; some extremely preterm infants (born <28 weeks) may have persisting events beyond this point. In these cases, caffeine is continued and the infant observed until apnoea-free. Persistent apnoea beyond 40 weeks PMA warrants investigation for other causes (vocal cord palsy, tracheomalacia, GOR, hypotonia syndromes).
Is a home monitor recommended after discharge for AOP?
Home cardiorespiratory monitoring is not routinely recommended by AAP or UK guidelines for infants who were preterm with AOP, as there is no evidence it reduces mortality or SIDS risk. Infants should be apnoea-free for the full post-cessation observation period before discharge. Families should receive CPR training, and safe sleep guidance applies.
プロのヒント
Caffeine has one of the best evidence bases of any neonatal drug. The CAP trial showed benefits not just in the short term but at 18 months corrected age, including a 36% reduction in BPD and a 40% reduction in motor impairment. Do not delay starting caffeine in any preterm infant at risk of AOP.
ご存知でしたか？
The caffeine dose used to treat AOP is approximately 5 times the amount found in an average cup of coffee, yet preterm neonates tolerate it well due to their immature hepatic CYP1A2 enzyme system, which metabolises caffeine very slowly — giving a half-life of 40–100 hours compared to just 3–5 hours in adults.
参考文献
- ›Schmidt B et al — Caffeine for Apnea of Prematurity (CAP) trial — NEJM 2006
- ›AAP — Apnea of Prematurity (Clinical Practice Guideline)
- ›Martin RJ, Abu-Shaweesh JM — Control of breathing and apnea in preterm infants — Neonatology 2005
- ›NICE — Caffeine Citrate for treating apnoea of prematurity in neonates (TA408)