neonatal apnea

M.Noori-Shadkam, MD-MPHNeonatologist

Cessation of airflow for at least 20 seconds or accompanied by bradycardia or cyanosis. Bradycardia and cyanosis are usually present after 20 sec. of apnea. After 30 to 45 sec., pallor and hypotonia are seen, and infant may be unresponsive to tactile stimulation.

V Vickers 2006

Apnea is Associated with Many Clinical Conditions:

• Intraventricular bleedMay see hypoventilation, apnea or respiratory arrest

Subtle seizuresAlong with fluttering eyelids, drooling or sucking,

tonic posturing

Sepsis Bacterial (GBS, staph. Proteus, Listeria,

Coliforms Viral (RSV, paraflu, herpes, CMV Chlamydial NEC

V Vickers 2006

• Congestive Heart Failure– PDA and CHD– Due to decreased lung compliance– Respiratory muscle fatigue– Chest wall distortion– Hypoxemia

Respiratory Distress Syndrome Due to atelectasis, work of breathing, fatigue May lead to chronic lung disease

Anemia oxygen carrying capacity of blood Arterial pressure perfusing CNS

Polycythemia blood viscosity and blood flow to CNS begins at 2-4 hours of age

V Vickers 2006

High temperature of environment Feeding problems

overdistention of stomach aspiration GER (gastroesphogeal reflux) with or without

aspirationsdue to laryngospasmstimulation of irritant receptors in lower esophagus

causing ‘reflux apnea’some reflux is common (laundry issue only?)

Metabolic conditions Hypoglycemia Hypocalcemia Hypernatremia Alkalosis

Others Myelomeningocele Meningitis

Causes

• CNS: (Abnormality,Encephalitis,Meningitidis,ICH,…)

• Upper & lower Air way: (choanal A.,congestion, RDS,pneumonia,…) Cardiovascular:

(Malformation,hypotention,hypertention,…)Digestive system:(GER,NEC,Distention,…)Other:

(Sepsis,Anemia,Hypothermia,Hyperthermia,pain,metabolic disorder,…)

• Recurrent sequences of pauses in respiration lasting for 5-10 seconds and followed by 10-15 seconds of rapid respiration.

• As many as 25% of all preterm infants who weigh <1800 g (34 Week) have at least one apneic episode. Essentially all infants <28 Week have apnea.

PREMATURITY Impaired Inhibitory Oxygenation Reflexes

APNEA

Infection CNS pathologyMetabolic disorders

Specific causes of apnea

Preterm infants respond to a fall in inspired oxygen with a transient hyperventilation followed by hypoventilation and sometimes apnea.

The Respiratory Pump

• The neonatal diaphragm• The ribcage and chest wall

muscles

The Neonatal Diaphragm

In the relaxed state is located higher in the

ThoraxInc. insp. pressure

Muscle fibers• Type I: fast-oxidative, 20% fatigue

resistant• Type IIa: fast-oxidative, fatigue

sensitive• Type IIb: slow oxidative, fatigue

resistant

The Neonatal Diaphragm

Is attached to a more pliable chest wall

Distortion

Dec. tidal volume

The Neonatal Diaphragm

The Newborn is Predisposed to Fatigue of Resp. Muscles Because of:• The reduced number of fatigue resistant

fibers in the diaphragm• A pliable chest wall• The rapid RR, which minimizes relaxation

time for perfusion of the diaphragm• The work of breathing associated with CL and CW

Consequences of ApneaGas exchange is compromised due to:• PA CO2, PAO2•Extrapulmonary shunting•Muscle relaxation

Types of Neonatal Apnea

1.Central (diaphragmatic)2.Peripheral (obstructive)3.Mixed

• All preterm infants below 35 WG must be monitored for at least the first week after birth. Monitoring should continue until no significant apneic episode has been detected for at least 5 days.

• Because impedance apnea monitors may not distinguish respiratory efforts during airway obstruction from normal breaths, heart rate should be monitored in addition to, or instead of, respiration.

• BP should be measured frequently and hypotension with oliguria< 2 mL/kg/h should be treated accordingly

• Hct should be> 45% ???

1. Prevent hyperflexion of the neck2. Nurse the baby in prone position3. Set the thermal environment to obtain

a central temperature of 36.5-37⁰ C4. Minimize the duration and rate of

pharyngeal suction cont’d

5. Place the orogastric tube carefully 6. Avoid sudden gastric distension7. Continuous gastric feeding if apnea

occurs with gavage8. Warm air and oxygen to incubator

temperature

Nursing Management During Apneic Episode1.Check infant at once2.Cancel alarm3.Stimulate if there is no

obvious vomit4.Suction

cont’d

Nursing Management During Apneic Episode5. Give O2 via face mask in same

concentration as infant had been receiving

6. Summon help if infant does not respond

7. Document and report8. Intubation if indicated

Management of Idiopathic Apnea

• When apneic spells are repeated and prolonged, (i.e., more than 2 to 3 times/h.) or when they require frequent bag and mask ventilation, treatment should be initiated.

cont’d

Management of Idiopathic Apnea

• Diagnosis and treatment of specific causes• Nursing care• Nasal CPAP (4-6 cm H2O)• Methylxanthine therapy• Increased environmental O2 only as necessary

to maintain adequate baseline O2 saturation. Often associated with treatment of anemia

• Assisted ventilation if all else fails

Management of Idiopathic Apnea

A. General measures1. Diagnosis and treatment of specific causes2. SO2 : 85-95%3. Avoid reflexes that may trigger apnea. Suctioning of the pharynx should be done carefully, and oral feeding should be avoided.

cont’d

Management of Idiopathic Apnea

4. Position of extreme flexion or extension of the neck should be avoided, to reduce the likelihood of airway obstruction.

5. Avoid swings in environmental temperature.

cont’d

Management of Idiopathic Apnea

6. Consider a transfusions of PRBCs if the Hct is <25% and the infant has episodes of apnea and bradycardia that are frequent or severe while methylxanthine levels are therapeutic.

cont’d

Management of Idiopathic Apnea

B. Nasal CPAP (4-6 cm H2O) can reduce the number of mixed and obstructive apneic spells.

C. Methylxanthine (caffeine of theophylline) therapy, commencing with a loading dose followed by maintenance therapy, and serum level monitoring, especially for theophylline.

D. Assisted ventilation if all else fails

• PaO2 with increased lung volume & C• Work of breathing• Splitting of the upper airways• Elimination of the intercostal

inspiratory- inhibitory reflex

Pharmacologic Mechanisms for Methylxanthine • Competitive effect on adenosine receptors• Sensitivity of respiratory center to CO2• Afferent nerve traffic to brain stem• Catecholamine response• Central stimulation (inspiratory drive)• Improved skeletal muscle contraction• Improved metabolic homeostasis• Improved oxygenation via increased cardiac

output and decreased hypoxic episodes

Signs of Toxicity in Infants Receiving Theophylline• Failure to gain weight 10-20 µg/mL• Sleeplessness• Irritability • Tachycardia• Hyperglycemia• Vomiting 20 µg/mL• Diuresis/dehydration• Jitteriness > 20 µg/mL• Hyperreflexia• Cardiac arrhythmias > 40 µg/mL• Seizures