Apnea of Prematurity
Introduction to Apnea of Prematurity
Apnea of prematurity (AOP) is a common condition affecting premature infants, characterized by a cessation of breathing for 20 seconds or longer, or a shorter pause accompanied by bradycardia, cyanosis, pallor, and/or marked hypotonia. It typically occurs in infants born before 35 weeks of gestational age and is inversely related to the degree of prematurity.
AOP is a developmental disorder caused by immaturity of the central nervous system and respiratory control mechanisms. It is a diagnosis of exclusion, and other causes of apnea must be ruled out before diagnosing AOP.
Pathophysiology of Apnea of Prematurity
The pathophysiology of AOP is multifactorial and involves:
- Immature respiratory control: The respiratory center in the brainstem of premature infants is not fully developed, leading to unstable breathing patterns.
- Altered chemoreceptor sensitivity: Premature infants have a decreased response to hypercapnia and hypoxia, which normally stimulate breathing.
- Immature pulmonary reflexes: The Hering-Breuer inflation reflex, which helps maintain regular breathing, is not fully functional in preterm infants.
- Upper airway instability: The pharyngeal and laryngeal muscles of premature infants are weak, potentially leading to airway collapse.
- Altered sleep states: Premature infants spend more time in active sleep, which is associated with irregular breathing patterns.
Risk Factors for Apnea of Prematurity
Several factors increase the risk of AOP:
- Gestational age less than 35 weeks
- Low birth weight
- Intrauterine growth restriction
- Maternal smoking during pregnancy
- Anemia
- Intraventricular hemorrhage
- Necrotizing enterocolitis
- Sepsis
- Hypothermia
- Metabolic disturbances (e.g., hypoglycemia, hypocalcemia)
Clinical Presentation of Apnea of Prematurity
AOP typically presents with the following features:
- Cessation of breathing for 20 seconds or longer
- Shorter pauses in breathing accompanied by:
- Bradycardia (heart rate < 100 beats per minute)
- Cyanosis or pallor
- Hypotonia
- Decreased oxygen saturation (< 80%)
- Periodic breathing (recurrent cycles of breathing followed by short pauses)
AOP can be classified into three types:
- Central apnea: Absence of both respiratory effort and airflow
- Obstructive apnea: Continued respiratory effort without airflow
- Mixed apnea: Combination of central and obstructive components
Diagnosis of Apnea of Prematurity
Diagnosis of AOP involves:
- Clinical observation: Monitoring for apneic episodes, bradycardia, and desaturation events
- Continuous cardiorespiratory monitoring: To detect and record apneic episodes
- Pulse oximetry: To measure oxygen saturation levels
- Exclusion of other causes: Ruling out conditions such as sepsis, metabolic disorders, and neurological issues
- Polysomnography: In some cases, to differentiate between central and obstructive apnea
Additional diagnostic tests may include:
- Complete blood count
- Blood cultures
- Electrolyte panel
- Cranial ultrasound
- Echocardiogram
Management of Apnea of Prematurity
Management of AOP involves a multifaceted approach:
- Supportive care:
- Proper positioning (prone or side-lying)
- Maintaining optimal environmental temperature
- Avoiding neck flexion
- Pharmacological interventions:
- Caffeine citrate (first-line therapy)
- Loading dose: 20 mg/kg
- Maintenance dose: 5-10 mg/kg/day
- Theophylline (alternative if caffeine is unavailable)
- Caffeine citrate (first-line therapy)
- Respiratory support:
- Nasal continuous positive airway pressure (CPAP)
- High-flow nasal cannula
- Mechanical ventilation (in severe cases)
- Oxygen supplementation: To maintain target oxygen saturation levels
- Treatment of underlying conditions: Such as anemia, infection, or metabolic disorders
- Monitoring and documentation: Continuous cardiorespiratory monitoring and accurate recording of apneic episodes
Complications of Apnea of Prematurity
Potential complications of AOP include:
- Hypoxic-ischemic brain injury
- Retinopathy of prematurity
- Neurodevelopmental impairment
- Prolonged hospitalization
- Increased risk of sudden infant death syndrome (SIDS)
- Failure to thrive
- Cardiovascular instability
Prognosis of Apnea of Prematurity
The prognosis for infants with AOP is generally good:
- Most cases resolve by 36-40 weeks postmenstrual age
- Extremely preterm infants may experience apnea beyond term-equivalent age
- Long-term neurodevelopmental outcomes are generally not affected if AOP is properly managed
- Regular follow-up is essential to monitor for any potential long-term effects
Factors influencing prognosis include:
- Gestational age at birth
- Severity and frequency of apneic episodes
- Associated comorbidities
- Adequacy of treatment and management
Apnea of Prematurity
- What is the definition of apnea of prematurity?
Cessation of breathing for ≥20 seconds or shorter if accompanied by bradycardia or oxygen desaturation in premature infants - At what gestational age is apnea of prematurity most common?
Less than 28 weeks gestation - What are the three main types of apnea in premature infants?
Central, obstructive, and mixed apnea - Which neurotransmitter imbalance is associated with apnea of prematurity?
Decreased sensitivity to carbon dioxide (CO2) - What is the primary treatment for apnea of prematurity?
Caffeine citrate - How does kangaroo care affect the incidence of apnea in premature infants?
It may reduce the frequency of apneic episodes - What is the role of continuous positive airway pressure (CPAP) in managing apnea of prematurity?
It helps maintain airway patency and reduces obstructive apnea - At what postmenstrual age do most premature infants outgrow apnea of prematurity?
36-40 weeks postmenstrual age - How does anemia affect apnea of prematurity?
Anemia can exacerbate apnea by reducing oxygen-carrying capacity - What is the recommended initial dose of caffeine citrate for treating apnea of prematurity?
Loading dose of 20 mg/kg followed by maintenance dose of 5-10 mg/kg/day - How does prone positioning affect apnea in premature infants?
It may reduce the frequency of apneic episodes - What is the role of doxapram in managing apnea of prematurity?
Used as a second-line treatment when caffeine is ineffective - How does sepsis affect apnea of prematurity?
It can increase the frequency and severity of apneic episodes - What is the significance of periodic breathing in premature infants?
It is a normal breathing pattern that may be mistaken for pathological apnea - How does gastroesophageal reflux (GER) relate to apnea of prematurity?
GER may trigger apneic episodes, but the causal relationship is controversial
