Apnea of Prematurity Workup

Updated: Nov 06, 2016
  • Author: Dharmendra J Nimavat, MD, FAAP; Chief Editor: Ted Rosenkrantz, MD  more...
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Workup

Laboratory Studies

A CBC count and cultures of blood, urine, and spinal fluid are necessary if a serious bacterial or fungal infection is suspected in patients with apnea of prematurity (AOP). Obtain appropriate viral cultures or collection of body fluid for polymerase chain reaction (PCR) analyses if a viral pathogen is suspected.

A C-reactive protein level measured at 36-48 hours after birth may be useful for excluding infection (see Maternal Chorioamnionitis).

Tests for ammonia, amino acid profiles in blood or urine, and organic acid levels in blood and urine are essential if a metabolic disorder is suspected. Testing of pyruvate and lactate concentrations in the blood and cerebrospinal fluid (CSF) may be diagnostically helpful when inborn errors of metabolism are among the differential diagnosis. The presence of ketones in the urine may indicate organic acidemia.

Serum electrolyte, calcium, magnesium, and glucose levels can be useful for diagnosing a recent stressful condition, a metabolic process, or chronic hypoventilation.

Analysis of the stool for different toxins related to botulism may reveal a cause in an infant with apnea, constipation, clinically significant hypotonia, difficulty swallowing or crying, or absent eye movements. [105]

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Imaging Studies

Chest radiography and/or a nuclear medicine milk scanning can be helpful if the child has persistent but unexplained lower airway symptoms (eg, wheezing and/or repetitive regurgitation after feeding, rumination). [106]

In cases of airway obstruction, stridor, or unexplained pathologic obstructive apnea, helpful upper airway evaluations include lateral neck radiography, head and neck 3-dimensional tomography, and otolaryngologic evaluation (eg, fiberoptic assessment of the larynx through the nose during spontaneous breathing). [107]

Imaging studies of intracranial pathology are necessary when hemorrhage is suspected or when findings include dysmorphic facial and somatic features, abnormal neurologic results, disordered hair whorls, and/or mental status changes.

A barium swallow study is useful if the infant has signs of swallowing dysfunction or anatomic anomalies (eg, an esophageal web, tracheoesophageal fistula).

A gastric-emptying study and abdominal sonography are useful in patients whose clinical picture includes a generalized gastrointestinal motility disorder or pyloric stenosis.

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Other Tests

Obtain a polysomnographic, or continuous multichannel, recording to measure the chest-wall movement, nasal and/or oral airflow (or change in air temperature), O2 saturation, and heart rate trend. A 2-channel pneumogram that is used to measure only chest-wall excursion and trends in heart rate provides insufficient information. The following results are diagnostic:

  • Central apnea - Absence of nasal airflow and wall movement (This diagnostic finding on polysomnography recording may be used in lieu of pneumogram.)

  • Obstructive apnea - Lack of airflow despite chest-wall movement

  • Mixed apnea - Combined results of central and obstructive apnea

If gastroesophageal reflux (GER) is suspected, note the intraesophageal pH as part of the multichannel recording.

Consider obtaining an electroencephalogram (EEG) in infants who have suspected apneic seizures or who have persistent pathologic central apnea without an identifiable cause.

Obtain an echocardiogram and consult a cardiologist if the patient's history or physical findings (eg, feeding difficulties, heart murmur, cyanosis) suggest cardiac disease.

ECG results are useful in patients with severe unexplained tachycardia or bradycardia. Abnormalities in cardiac conduction (eg, prolonged-QT syndrome) are infrequent but important causes of apnea during infancy.

Evaluate patients for unilateral choanal stenosis and choanal atresia by passing a small-diameter feeding tube through both nares. Three-dimensional tomography is probably the method of choice for definitively diagnosing upper airway malformations.

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Procedures

Several studies may reveal diagnostic findings in selected infants. These include fiberoptic examination of the larynx through the nose during spontaneous breathing, direct laryngoscopy, and bronchoscopy (which is usually performed with the patient under anesthesia).

Emergency or scheduled tracheostomy may be used to manage severe airway obstruction caused by a number of conditions. Tracheostomy might occur after the airway is stabilized by using endotracheal intubation. Jaw-distraction surgery has been used to avoid tracheostomy in neonatal conditions (eg, Robin sequence) that involve severe micrognathia as a component of malformation. [108, 109]

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