APNEA In Neonates

Definition Of Apnea In Neonates

 In newborns, apnea is characterized by a respiratory stoppage that lasts 20 seconds or more.  Any shorter respiratory pause (less than 20 seconds or between 10 and 20 seconds) if it is accompanied by a change in color or bradycardia. Pallor or cyanosis are the two possible color changes.

If ayoungster stops breathing for 22 seconds without experiencing any change in heart rate or color. Another baby stopped breathing for sixteen seconds, but this baby also had bradycardia, which caused them to become blue. The neonate is regarded as apneic in both scenarios.

 A fairly typical occurrence, especially in premature newborns, is periodic breathing. In newborns, respiration occurs quickly followed by a pause or stoppage that lasts anywhere from three to ten seconds. This disparity is very typical. The total respiratory rate is within normal bounds; the typical duration of that brief pause is three to ten seconds. Desaturation, a change in the child's hue, or general condition are not brought on by it.

Periodic Breathing

Where there is, periodic breathing is employed. It is a typical occurrence. It is a common occurrence, especially in premature babies. Breathing pauses are short, lasting three to eight seconds, or longer if they remain more than three seconds, and they are not accompanied by a change in heart rate or color.

Prominent Bradycardia- Any neonatal heart rate that is less than 80 beats per minute is considered significant bradycardia. Any newborn with bradycardia is often regarded as significant if respiratory stoppage is also present. Newborns often have heart rates of fewer than 100 beats per minute.  Considerable Hypoxemia.  Anytime a child's SPO2 level is present, the term "significant hypoxemia" is applied. less than 80–85% of the total. Hypotonia may coexist with apnea.

Classification Of Apnea

Apnea is divided into three parts

1.  Central Apnea

 Between 30 and 40 percent of cases had central apnea.  The brain is not producing a respiratory drive in central apnea.  The brain does not provide any signals to the respiratory muscles to start breathing. It has been demonstrated that central respiratory drive loss happens less frequently.

Low gestational age tends to be associated with a higher frequency of sporadic loss of central drive.  The infant has greater authority. Apnea may be brought on by a certain level of cerebral immaturity. Additionally, secondary alterations resulting from meningitis, convulsions, or any brain-related condition might cause central apnea.  No chest wall movement or respiratory consequences are seen.

2.  Obstructive Apnea

 Only around 10% of obstructed cases have obstructive apnea.

There is movement in the chest wall and a central respiratory drive, but no air.  In spite of the apparent movement of the chest wall, there is no airflow. This may occur for a number of reasons.  The cause of purely obstructive apnea is often positional changes, such as extensive neck flexion. Pharyngeal muscle or pharyngeal instability, as well as extensive thick secretions in the airway, can also cause it.  Respiratory movements, or respiratory efforts, are present and frequently, albeit less frequently, may be slightly increased.

 3.  Mixed Apnea 

In 50 to 60 percent of cases, mixed apnea—a combination of central and obstructive apnea—is the most prevalent type. Prematurity apnea is a common case of a mixed one.

Initially, there will be a culmination of secretion or abnormal positioning, which will start obstructive apnea. As a result of that obstructive apnea, there will be an abnormal response leading to central apnea as well. In prematurity, the child is preterm and the brain is immature, but this does not cause a lack of respiratory drive. It will therefore be a mixed apnea because both elements are present.

Q. What Is The Type Of Apnea In Apnea Of Prematurity?

Because the brain is still developing, mixed apnea is the type of apnea seen in preterm. The obstructive apnea that comes before the central apnea will cause it to occur.

Etiology Of Apnea

• It can broadly be divided into primary and secondary. 

Primary

• It does not have any external underlying cause. 
• It is just that the brain is immature.
• It is synonymous with the apnea of prematurity.

Secondary

It happens for an underlying, outside cause.  Temperature instability, including hypo- or hyperthermia and abrupt temperature swings, can cause it.  Metabolic reasons: hypoglycemia, hypocalcemia, hypernatremia, hyponatremia, and metabolic acidosis are examples of metabolic causes. Any of them may result in secondary apnea.  Hematological causes: Apneic episodes have been linked to anemia and polycythemia,

Neurological causes include intracranial hemorrhage, brain abnormalities, inborn metabolic problems, seizures, newborn seizures, and CNS infections such as meningitis. Respiratory distress syndrome (RDS), pneumonia, pneumothorax, and pulmonary hemorrhage are examples of pulmonary causes.
Congenital cardiac disease and patent ductus arteriosus (PDA) are the causes of CVS. Necrotizing enterocolitis and reflux disease are the causes of GIT.

Infections: meningitis, newborn sepsis, etc. Tachypnea is more frequently caused by RDS; but, in some cases of severe RDS patients, apnea episodes can occur in between tachypneic episodes; this is especially the case for individuals with severe RDS. In children under 35 weeks of age, a diagnosis of exclusion is apnea of prematurity.

Apnea Of Prematurity (AoP)                                   

Apnea, typically observed in neonates born before 35 weeks of gestation. The brainstem and peripheral chemoreceptors' immaturity is the cause. The ventilatory response to hypoxia and hypercarbia is aberrant and partial, but there isn't a secondary explanation that can be found.

Incidence and Time of First Specification

The incidence of AoP is inversely correlated with gestational age, ranging from 10 to 20% at 34 weeks to over 60% at 28 weeks or fewer. The first week of life, or days two through six, is when the majority of cases happen.  The typical time of presentation is after 24 hours, although some patients choose to present later.

Q. What Are The Conditions Where Delayed Presentation May Be Seen?

If respiratory distress syndrome (RDS) or hyaline membrane disease (HMD) coexist, there may be a minor delay in presentation. However, if isolated apnea in a premature child is the result of prematurity apnea, it will invariably occur in 2 to 6 days.  Apnea that develops during the first 24 hours of life and after seven days is more likely to have a secondary etiology than apnea of immaturity (AoP), according to AIIMS protocol.

Points to Remember 

Bradycardia, which is primarily sinus bradycardia followed by AV nodal bradycardia, occurs one to two seconds after apnea.
  All premature babies born before 35 weeks must have their AoP monitored.  AoP frequently exhibits mixed apnea, with obstructive apnea emerging first and then central apnea.

AoP is an exclusionary diagnosis.  AoP in full-term newborns typically requires a thorough assessment. Therefore, you should conduct several investigations on a youngster exhibiting apnea whenever it occurs.  REM sleep is associated with a higher prevalence of apnea than NREM sleep.

Q. What Age Group Requires Monitoring For Aop?

Ans. Newborns less than 35 weeks.

Management Of Apnea In Newborns

Emergency Management

Tactile stimulation is the first action we take in emergency management. Many apnea patients, including those with preterm apnea, react to tactile stimulation. Identify and treat the obstructive causes of apnea concurrently with tactile stimulation.

Anomalies relating to flexion may be connected. Therefore, flexion must be eliminated. • If the child has any secretions, it would be preferable to suction them after slightly extending their neck.  In the event that apnea occurs or if there is no improvement. Positive pressure ventilation, or bag and mask ventilation, needs to be taken into account for these individuals. Launch the oxygen if room air tests reveal that the youngster is hypoxic.

Investigations

Hemoglobin testing can be used to rule out polycythemia or anemia. Examine the screen for sepsis. This will exclude sepsis as the reason behind the apnea.
• Measure serum electrolytes, calcium, and glucose levels.
• Look for an ultrasound of the brain.
• Get an echocardiogram and chest x-ray as a screening test for cardiac and pulmonary reasons.
•Select for the care of preterm apnea if the kid is under 35 weeks old and the cause cannot be determined by the aforementioned investigations.

Also Read: WHO Recommendations For Care Of The Preterm Or Low Birth Rate Infants-2022

Management In Apnea Of Prematurity

The management of apnea, prematurity will be of two types. 

General Measures

Pay attention to the child's placement since mixed apnea, which is common in apnea prematurity, can be caused by obstructive causes leading to central causes.  Make sure the youngster is in a thermally neutral environment to prevent hypo- or hyperthermia.

Verify the child's SPO2 is appropriate. It should not become hypoxic or hypoxemia.  Making sure the child is fed, deciding whether to offer feeds, or thinking about IV fluids.  Verify that the youngster has no secretions on them.

Specific Therapy

Methylxanthines will always be the first-line therapy for the individual condition.  The first-line agents are thought to be methylxanthines. There are two kinds of methylxanthines. In methylxanthines, caffeine citrate is the preferred medication; theophylline is an alternate. 

As competitive inhibitors of the adenosine receptor, the aforementioned medications work via this mechanism.The preterm newborn's central apnea has been linked to adenosine. Therefore, these methylxanthines function by inhibiting adenosine receptors.

Begin with the dosage of methylxanthine.Theophylline and methylxanthines both increase diaphragmatic contractility. They lessen apneas linked to hypoxia. They enhance reflex reactions related to hypercarbia, which reduces the likelihood that the infant may experience apnea.

If methylxanthines are well received, keep giving them until the postnatal age is at least 34 weeks or greater and there hasn't been any apnea for the previous five to seven days. These are the instances at which methyl xanthine is discontinued when both requirements are met.However, nasal CPAP (nCPAP) should be started as a second line of treatment if these individuals show little or no response to methylxanthines.

Take into consideration nasal CPAP if patients do not respond well to methylxanthines, such as caffeine citrate, aminophylline, or theophylline. In circumstances when methyl xanthine is not responsive, nasal CPAP within a range of around 3 to 5 cm of saline effectively avoids apnea. It produces a splitting motion in order to act.

Enter for nasal intermittent positive pressure ventilation (IPPV) if the patient's condition does not improve with nasal CPAP. If the patient doesn't improve even after that, you'll need to put them on a ventilator and provide mechanical ventilation.  Low pressure ventilation is often required for all patients placed on mechanical ventilation.

 Low power levels.  A saline PIP measuring 10 to 12 millimeters
  PEEP in saline ranging from 3 to 5 cm.  A TI of roughly 0.35 is ideal.  The pace ought to be reduced to roughly 20 to 25 beats per minute. FIO2 ought to be quite low. The correct value is a point to 102.3, or 21%.  Very little or no additional oxygen 30% FIO2 is permissible.  The likelihood of preterm apnea considerably decreases with age.

Also Read: Fungal Infections In Neonates

Caffeine Citrate

Doses

The loading dose for caffeine citrate is 20 mg/kg. then 5 to 10 mg/kg each day. Because caffeine citrate has a half-life, a single daily dose is adequate. Give by IV or oral since both are accessible.

• The amount of caffeine base is approximately half that of caffeine citrate. Half of the dose, or 10 mg/kg of caffeine base, will be administered.
• If the term "caffeine base" is used, the daily maintenance dose will also be halved.
• Eight to twenty micrograms/ml is the therapeutic medication level.
• The half-life on average is roughly 101 hours.
• The safety profile is good. Its therapeutic window is quite wide.
• While certain adverse effects, such as tachycardia at larger dosages, are possible, they are often easier to handle than theophylline.

Theophylline 

• Dosage: Theophylline should be taken at a loading dose of 5 to 6 mg/kg and then 1.5 to 2-3 mg/kg every 8 to 12 hours.
• The therapeutic index for the drug level is limited to 5 to 10 micrograms per milliliter.
• The half-life is much shorter, ranging from 13 to 29 hours.
• Adverse Safety profile: The therapeutic window is small.Common adverse effects of theophylline and caffeine citrate include jitteriness, hyperglycemia, tachycardia, food intolerance, and vomiting. With theophylline, these side effects are more frequent.

Points To Remember

• A substitute for The HHH fnc (Heated Humidified High-Flow Nasal Cannul), which delivers oxygen or airflow at 1-4 liters per minute, is the CPAP used to treat newborn apnea. However, nasal CPAP is more effective than this method, making it a viable substitute.
• Moreover, caffeine citrate lowers the risk of BPD later on.
• The link between GER and apnea has not been established.
• It is ironic that giving PPIs or H2 blockers to preterm babies can raise their risk of apnea. Thus, we ought to discourage them. Preterm neonates should not be given any prokinetic medications, including lansoprazole, domperidone, or lansoprazole combined with domperidone.
• According to Nelson, preterm apnea in 92% of newborns disappears by 37 weeks of postmenstrual age. And by 40 weeks of postmenstrual age, it resolves in 98% of cases. Apneic episodes in AOP frequently last longer than 37 to 40 weeks. Particularly in kids born before 28 weeks of pregnancy. Therefore, it is necessary to maintain the methyl xanthine medication and do further assessments, such as checking for CNS problems and gastric reflux in these patients.
• At 44 weeks postnatal age, home monitoring can be safely stopped in the case that no noteworthy incidents occur.
• There is no correlation between AoP and SIDS (sudden infant death syndrome).
• In extremely premature infants, there is no regulation for preventive measures and thin therapy to avoid AoP.

Also Read: Hearing Loss in Nicu Graduates

Hope you found this blog helpful for your NEET SS Pediatrics Neonatology Preparation. For more informative and interesting posts like these, keep reading PrepLadder’s blogs.