![]() ![]() Bradycardia by itself is often a sign of obstructive apnea. An alarm should sound if respiration ceases for more than 20 seconds, or if the heart rate drops below 100 bpm. ![]() This is done by applying ECG leads to the chest which are connected to a bedside respiratory and heart rate monitor. SurveillanceĪll newborns less than 34 weeks gestational age, or less than 1800 grams birth weight, should be monitored for both apnea and bradycardia. Mixed Apnea - A combination of both types of apnea representing as much as 50% of all episodes. Excessive secretions in the nasopharynx and hypopharynx may also cause obstructive apnea. Neck flexion will worsen this form of apnea. Once collapsed, mucosal adhesive forces tend to prevent the reopening of the airway during expiration. The pharynx collapses from negative pressure generated during inspiration, because the muscles responsible for keeping the airway open, the genioglossus and geniohyoid are too weak in the premature infant. Obstructive Apnea - A pause in alveolar ventilation due to obstruction of airflow within the upper airway, particularly at the level of the pharynx. This reflex apnea can be induced by gavage feeds, aggressive pharyngeal suctioning and gastroesophageal reflux. ![]() However, stimulation of these same receptors in the premature infant results in apnea. For example, stimulation of laryngeal receptors in the adult results in coughing. The premature infant also manifests an immature response to peripheral vagal stimulation. This is due to immaturity of brainstem control of central respiratory drive. In other words, there is no signal to breathe being transmitted from the CNS to the respiratory muscles. Pathophysiology Mechanisms of apnea of prematurityĬentral Apnea - A pause in alveolar ventilation due to a lack of diaphragmatic activity. Postnatal exposure to sedatives, hypnotics or narcotics. Drugs - Prenatal exposure with transplacental transfer to the neonate of various drugs (narcotics, beta-blockers).Temperature Regulation - Hypothermia or hyperthermia.Gastrointestinal - NEC or gastroesophageal reflux.Metabolic - Hypocalcemia, hypoglycemia, hyponatremia or acidosis.Pulmonary - Impairment of oxygenation and ventilation from lung disease (surfactant deficiency disease, pneumonia, transient tachypnea of the newborn, meconium aspiration, etc.).Cardiovascular - Impairment of oxygenation from congestive heart failure and pulmonary edema (PDA, coarctation, etc.), or from shunting (cyanotic heart disease).Neurological - Intraventricular hemorrhage, intracranial hemorrhage, neonatal seizures, perinatal asphyxia, or other pathology which could lead to increased intracranial pressure.Infection - Sepsis, especially in the first day of life, and nosocomial infections and/or NEC in the first weeks of life.The most common cause of apnea in the NICU is apnea of prematurity, but first ALWAYS investigate and rule out the following disorders: SequelaeĪpnea in premature infants can result in a failure of the mechanisms that protect cerebral blood flow, resulting in ischemia and eventually leukomalacia.ĭuring apneic episodes, in an attempt to protect cerebral blood flowcardiac output is diverted away from the mesenteric arteries resulting in intestinal ischemia and possibly necrotizing enterocolitis (NEC). Apnea at UIHC is defined as cessation of breathing for 20 seconds with the above symptoms. Peer Review Status: Internally Peer Reviewed DefinitionĪpnea is a "pause in breathing of longer than 10 to 15 seconds, often associated with bradycardia, cyanosis, or both." (Martin et al). ![]()
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