APNEA of prematurity and other causes in new borns

physiological changes that occur to new borns during birth includes some changes that fail to occur

1. APNEA D. AGEDO

2. OBJECTIVES Define apnea Describe the different types of apnea Identify the causes of apnea Discuss the pathogenesis Describe the management of apnea

3. BREATHING PATTERNS Normal breathing pattern in newborn can be divided into 4 types: REGULAR: infrequent, these are nearly equal breath-to- breath intervals IRREGULAR: unequal breath-to-breath intervals , commonly observed in preterm infants

4. : APNEA Cessation of respiratory activities/breathing for 20 sec or less accompanied by cyanosis, bradycardia , pallor, or hypotonia PERIODIC BREATHING: Recurrent sequences of pause in respiration lasting 5-10 seconds followed by 10 to 15 seconds of rapid respiration

5. TYPES OF APNEA PRIMARY APNEA SECONDARY APNEA CENTRAL APNEA OBSTRUCTIVE APNEA MIXED APNEA IDIOPATHIC APNEA OR APNEA OF PREMATURITY

6. PRIMARY APNEA This is initial cessation of respiratory movements after a period of rapid respiratory efforts as a result of asphyxia It is characterized by rise in heart rate but no significant changes in blood pressure Resolves by warmth, stimulation and/or oxygen administration

7. SECONDARY APNEA Occurs after a period of deep, gasping respirations and fall in blood pressure & heart rate resulting from prolonged asphyxia Neonate will not respond to stimulation & will require active resuscitation

8. CENTRAL APNEA Absence of airflow and respiratory effort Cause not well known though associated with : Altered levels of neurotransmitters in the CNS Immature, paradoxical response of neonate to hypoxia & hypercapnea Chest wall & chest wall neuromuscular signals instability

9. OBSTRUCTIVE APNEA Absence of airflow with continued respiratory efforts Associated with blockage of airway at the level of pharynx&/or larynx Hyperextension or flexion of the neck may lead to obstruction of the airway Causes obstruction of the airways at the neck & mouth could be due to anatomical abnormality eg macroglossia or micrognathia

10. MIXED APNEA A combination of central & obstructive apnea Obstruction usually occurs at the level of the pharynx

11. IDIOPATHIC APNEA Also referred to as apnea of prematurity Commonly observed in preterm infants Occurs mainly within the first week of life (usually within 24-48 hrs ) May persist longer at less than 28 weeks gestation

12. PATHOGENESIS IMMATURE CENTRAL RESPIRATORY CENTRE Decreased afferent traffic occurs due to: Poor CNS myelinization Decreased number of synapses Decrease dendritic arborization

13. Decreased neurotransmitters Fluctuating respiratory centre output

14. CHEMORECEPTORS Located in the medulla , carotid and aortic bodies , chemoreceptors relay information to the respiratory centre in the brain regarding pH, PO 2 & PCO 2 via the vagus & glossopharyngeal nerves Hypoxemia Hypercapnea

15. Biphasic response of preterm to hypoxia There is increased respiratory efforts within the first minute of hypoxia , followed by 2-3min of decreased respiratory rate & periodic breathing, respiratory depression & apnea Depressed response to hypercapnia. Preterm exhibit decreased sensitivity to increased CO 2 levels

16. THERMAL AFFERENTS Apnea is increased in hypothermic or hyperthermic environment

17. MECHANORECEPTORS Stretch receptors alter the timing of respiration : these are active in neonates than in adults . Vagal stimulation inhibit inspiration and/or prolonged expiration Pharyngeal collapse & airway obstruction are produced by negative pharyngeal pressures generated during inspiration Intercostal phrenic inhibitory reflex, an inward movement of the rib cage during inspiration, prematurely end inspiration

18. PROTECTIVE REFLEXES Stimulation of posterior portion of the pharynx while suctioning, inserting an ET tube or NGT or gastroesophageal reflux can stimulate apnea Pulmonary irritation receptors can produce apnea in response to direct bronchial stimulation Laryngeal taste receptors produce apnea in response to various chemical stimulation

19. SLEEP STATE 80% of neonatal apnea occur during day sleep sessions Respiratory depression occurs predominantly during rapid eye movement (REM) or transitional sleep Rapid eye movement

20. CAUSES/RISK FACTORS OF APNEA Prematurity Hypoxia Respiratory Disorder Cardiovascular Disorders Infection CNS Disorders Metabolic Disorders

21. DRUGS Maternal Drugs eg narcotics, analgesics, anesthesia Neonatal Drugs eg anticonvulsants, CVS drugs, narcotics

22. INCIDENCE Apnea & periodic breathing is common amongst the preterm 50% are < 1500gm 90% < 1000 gm Mixed apnea is common (50%) Central apnea (40%) Obstructive apnea (10 %)

23. Clinical presentation S & S depend on the duration and frequency of apnea Depends on the etiology Hypoxia Feeding intolerance Lethargy Temp instability Jitteriness

24. CNS depression Tachycardia/ bradycardia Hypotonia Desaturation seizures

25. Diagnosis History & physical presentation Lab evaluation: CBC, Septic screen, Radiologic evaluation: CXR r/o atelectasis , pneumonia, ivh EEG

26. MANAGEMENT

27. PHARMACOLOGIC RESPIRATORY STIMULANTS Methylxanthine therapy: caffein , theophylline & aminophylline Increases minute ventilation Improves CO 2 sensitivity Decreases hypoxic depression Enhance diaphragmatic activity Decreases periodic breathing Increase metabolic rates and oxygen consumption

28. Doxapram Potent non-specific respiratory stimulant Stimulates the peripheral chemoreceptors at low doses & central chemoreceptors at high doses Increases tidal volume & minute ventilation

29. Non-pharmacologic Position: prone head elevated position: chest wall stabilized & thoracoabdominal asychrony stabilized CPAP: (CPAP at 4-6 cm H 2 O) Oxygen by nasal cathers NGT KMC NTE Tactile stimulation Manage the cause