By Dr. Namrata Todurkar
Every parent in the NICU must have heard about the ‘dips,’ ‘events,’ or ‘apnea-bradycardia-desaturations (ABDs)’ during rounds or other times. These events are usually a cause of distress, concern, and frustration for families. What are these ‘events’ that NICU staff refer to, and why is it important to know more about them? This blog will discuss these ‘events,’ or in other words, ‘Apnea of Prematurity,’ in very simple terms.
What is Apnea of Prematurity?
Apnea is the stoppage of breathing for more than 20 seconds or a shorter breathing pause if associated with low oxygen saturation and/or low heart rate.
Picture ref: https://kidshealth.org/en/parents/aop.html
In preemies, it usually presents as an unstable breathing rhythm, reflecting the immaturity of the respiratory control system in their brain. Apnea can also be secondary to other conditions that need to be excluded before the diagnosis of apnea of prematurity (AOP) is made. At times, additional stresses in a premature baby — including infection, heart or lung problems, low blood count, low oxygen levels, temperature instability, feeding problems, or overstimulation — may cause or worsen apnea.
How common is Apnea of Prematurity?
The incidence of apnea increases with decreasing gestational age. Practically all infants born at less than 29 weeks will develop apnea, but this proportion decreases to 20% among those born at 34 weeks. It generally resolves by 36 to 37 weeks in infants born at more than 27 weeks’ gestation. Among more immature infants, apnea can often persist.
What are the Types of Apnea?
A. Central Apnea: Related to immaturity of the central nervous system.
B. Obstructive Apnea: Occurs due to obstruction in the airway, anywhere from the nose to the windpipe. Preemies have very soft windpipes that can easily become obstructed by a change in position or by secretions.
C. Mixed Apnea: A combination of both obstructive and central apnea, with one type triggering the onset of the other.
D. Periodic Breathing:A normal breathing pattern characterized by pauses in breathing for 5 to 10 seconds without changes in heart rate or skin colour. This is a normal phenomenon that requires no treatment.
Mixed apnea is the most common type (50%), followed by central (40%) and obstructive (10%).
How is it Treated?
Treatment for apnea depends on the likely causes, the frequency of the apnea spells, and their severity. Babies who appear otherwise healthy with only a few spells per day are simply observed and may be gently stimulated during their occasional episodes. Babies who are generally well but have multiple spells may be placed on caffeine to help stimulate their breathing. Caffeine is generally a very safe drug, with its most frequent side effects being an increased heart rate and gastroesophageal reflux. Proper positioning, modifications in feeding, oxygen, and, in some cases, ventilator support may be needed to assist in breathing. Along with its benefits in managing apnea, caffeine has been shown to aid in neurodevelopment and improve kidney health in preemies.
Caffeine is usually stopped after the baby has been apnea-free for a few days or once they reach 34 weeks corrected age. Caffeine stays in the body for about 5 to 7 days, so the baby needs to remain in the NICU to monitor for recurrence of apnea. Sometimes, babies are discharged home on caffeine, which will then be stopped by their paediatrician during follow-up.
Is it Possible to Prevent Apnea in Preemies?
Studies have shown that infants receiving kangaroo care experience fewer episodes of apnea and bradycardia. Providing a stable thermal environment and avoiding temperature fluctuations can also prevent apneic episodes. Developmental care in the NICU (nesting, bundling, minimal stimulation, hands-to-mouth position, pain relief), clustering of activities, and responding to the baby’s cues can help prevent apneic spells.
Discharge Considerations
A study of 1,400 infants born at ≤34 weeks’ gestation reported that a 5- to 7-day apnea-free period successfully predicted resolution of apnea in 94% to 96% of cases. However, the success rate was significantly lower for infants born at younger gestational ages. Additionally, there is often an exacerbation of apnea after immunizations or retinopathy of prematurity (ROP) examinations, while still in the NICU.
Each NICU has its own discharge policy for preemies, with a focus on the baby’s safety. However, discharge decisions are individualized based on each baby’s NICU journey.
What is the Risk of Apnea After Discharge?
There is no evidence to suggest that a diagnosis of apnea of prematurity is associated with an increased risk of sudden infant death syndrome (SIDS) or that home monitoring can prevent SIDS in former preterm infants. Although infants born preterm have a higher risk of SIDS, research does not support a causal link with apnea of prematurity. As such, routine home monitoring for preterm infants with resolved apnea of prematurity is not recommended.
Summary
Apnea of prematurity is one of the most common diagnoses in the NICU. It resolves with maturation, and in most infants, apnea resolves without long-term complications. However, resolution may be delayed in preemies born at less than 28 weeks’ gestation. Kangaroo care and developmentally supportive care play a major role in helping babies self-regulate and can prevent apnea of prematurity.
References:
Schmidt B, Roberts RS, Davis P, et al; Caffeine for Apnea of Prematurity Trial Group. Caffeine therapy for apnea of prematurity. N Engl J Med. 2006;354(20):2112–2121
Apnea of Prematurity Pediatrics (2016) 137 (1): e20153757. https://doi.org/10.1542/peds.2015-3757
Picture ref: https://kidshealth.org/en/parents/aop.html
Malloy MH. Prematurity and sudden infant death syndrome: United States 2005-2007. J Perinatol. 2013;33(6):470–475
Dr. Namrata Todurkar, MBBS, MD (Pediatrics), DNB (Pediatrics). Fellowship in Neonatology from National Neonatology Forum India. Fellow in Neonatal-Perinatal Medicine at the University of British Columbia. Areas of interest: Neonatal nutrition, Fluid and Electrolyte Management, Inborn Errors, Neurodevelopmental follow-up of preterm infants. Dr. Todurkar is a volunteer blogger at CPBF.
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