1. APNEA OF PREMATURITY
AoP
Apnea of prematurity –
Causes, pathogenesis, features and treatment (Apr ’13) (Nov ’06) (Apr ’05)
Apnea in a 3 day old preterm – 30 weeks gestational baby – causes and
management (Apr ’04)
2. DEFINITION
Apnea is defined as
cessation of respiration for longer than 20 sec,
or
shorter duration in presence of cyanosis or bradycardia.
3. INTRODUCTION
Apnea in preterm infants is usually related to immaturity of the central
nervous system and is called apnea of prematurity (AOP).
It can also occur secondary to other causes and is a common
manifestation of most neonatal diseases.
Incidence of AOP is inversely proportional to gestational age.
varies from 10% in infants born at gestation of 34 weeks
more than 60% in infants born at less than 28 weeks of gestation
4. TYPES OF APNEA
1.CENTRAL APNEA: (40%)
Characterized by total cessation of inspiratory efforts with no evidence of
obstruction.
2 OBSTRUCTIVE APNEA: (10%)
Infant tries to breathe against an obstructed upper airway,
Resulting in chest wall motion without airflow throughout apneic episode
3 MIXED APNEA: (50%)
Consists of obstructed respiratory efforts usually following central apnoea.
5. ETIOLOGY
Apnea can be due :-
Prematurity :AoP
Secondary causes
Common causes of secondary apnea include sepsis, pneumonia, asphyxia,
temperature instability and anemia.
Apnea of prematurity(AOP) :
Related to immaturity of the CNS.
This condition usually presents after 1-2 days of life (the detection may be
delayed by the presence of ventilatory support in the initial days of life) and
within the first 7 days.
AOP is a diagnosis of exclusion
Should be considered only after secondary causes of apnea have been
excluded.
6. ETIOLOGY
Secondary causes: include:
(a) Temperature instability: Hypothermia and Hyperthermia,
(b) Neurological: birth trauma, drugs, intracranial infections, intracranial haemorrhage, seizures,
perinatal asphyxia, congenital myopathies or neuropathies, placental transfer of narcotics,
magnesium sulphate, or general anaesthetics, central nervous system malformations,
(c) Pulmonary: respiratory distress syndrome (RDS), pneumonia, pulmonary haemorrhage,
obstructive airway lesion, pneumothorax, hypoxemia, hypercarbia, tracheal occlusion by neck
flexion,
(d) Cardiac: Congenital cyanotic heart disease CCHD, hypo/hypertension, congestive heart
failure CHF , Patent ductus arteriosus PDA , increased vagal tone
(e) Gastro-intestinal: Gastro oesophageal reflux, abdominal distension,
(f) Haematological: Anaemia,
(g) Infections: Sepsis, Pneumonia, Meningitis, NEC
(h) Metabolic: Acidosis, Hypoglycaemia, Hypocalcaemia, hyponatremia, hypernatremia and,
(i) Inborn errors of metabolism.
7. ETIOLOGY-in short
Apnea can be due :-
Prematurity :AoP
Secondary causes
Apnea of prematurity- due to immaturity of CNS
Secondary causes
1. Sepsis , Meningitis ,NEC
2. Asphyxia, ICH ,Seizures (CNS )
3. CCHD ,PDA (CVS )
4. RDS ,Pneumonia ,Pneumothorax ,Pulmonary hemorrhage (RESPI)
5. Temperature instability
6. Anemia.
7. Acidosis, Hypoglycaemia, Hypocalcaemia (Metabolic)
8. IEM
9. GER
A-Asphyxia Acidosis
P-Pneumonia PDA
N-NEC
E -Error of metabolism
A-Anemia
S-Sepsis
8. MONITORING
Babies <34 weeks gestation all should be monitored
for at least:
first 7 days of life or till absence of apneic episodes for at least 7 days.
APNEA MONITORS
PULSE OXIMETERS:
detect changes in heart rate and/ or saturation due to apneic episodes.
OTHER APNEA MONITORS
Movement sensors:
interpret chest/ abdominal movements as respiration.
fail to diagnose obstructive apnea
may not distinguish body movementsfrom breathing.
(i) Ripple type mattress
(ii) Mattress with sensory pad
9. MONITORING
Thoracic impedence based monitors:
Translate changes in thoracic impedence that occur with breathing
They also fail to diagnose obstructive apnea.
Respiratory inductive plethysmography:
It uses abdominal and thoracic movements during respiration.
Abdominal thoracic bands or the Graseby capsule are used
Magnatometer:
Electrical signal produced by chest or abdominal movement then can be
detected by the sensor.
10. DIFFRENTIAL DIAGNOSIS
PERIODIC BREATHING:
breathing for 10-15 seconds
followed by apnea for 5-10 sec
without change of heart rate or color.
SUBTLE SEIZURES:
Apnea is an uncommon presentation of a neonatal seizure in preterm infants.
Sudden alteration in muscle tone, twitching movements, vacant stare and up rolling of
eyes suggests a seizure.
Tachycardia preceding/ accompanying an apneic attack usually suggests seizure
11. EVALUATION
Onset within the first 7 days in a premature infant (gestation < 34 weeks) would be
suggestive of apnea of prematurity (AOP).
Review History for possible causes of secondary apnea :
Perinatal asphyxia, Maternal drugs, Neonatal sepsis and Feed intolerance.
Examine baby for :
Temperature instability,
Pallor
cardiac murmur for PDA and
Poor perfusion, Hypotension
Jaundice,
Investigations To exclude common causes of secondary apnea.
Blood glucose, Arterial blood gas, Hematocrit, Electrolytes,
Septic screen, Blood culture
Chest x-ray, Abdominal x-ray,
Ultrasound head
other investigations depending on the history and physical examination.
12. MANAGEMENT
EMERGENCY TREATMENT
Checked for bradycardia, cyanosis and airway obstruction
1. Neck positioned in slight extension
2. Suction of Oro-pharynx: if required gently
3. Tactile stimulation should be given. Most apneic spells respond to tactile stimulation.
4. HBO2 or NpO2 Oxygen by head box or nasal cannula is provided if the infant is hypoxic
(maintain saturation between 90-93%).
5. BMV Ventilation with bag and mask using 100% oxygen If the neonate continues to
remain apneic and does not respond to tactile stimulation
6. PPV Positive pressure ventilation. If BMV fails to initiate spontaneous respiration
13. MANAGEMENT
GENERAL MEASURES:
1) Maintain airway, breathing and circulation
2) Avoid vigorous suctioning of oro-pharynx
3) Avoid oral feeds in case of repeated episodes of apnea requiring BMV
4) Avoid hypo or hyperthermia .
5) Treatment of the underlying cause: sepsis, anemia, polycythemia,
hypoglycemia, hypocalcaemia, respiratory distress syndrome (RDS).
6) Transfuse PRBCs if hematocrit <30%.
14. MANAGEMENT
SPECIFIC MEASURES FOR AOP
include:
A. Drugs including Caffeine ,Aminophylline, Doxapram
B. CPAP :Continuous positive airway pressure
C. Mechanical ventilation
D. Kinesthetic stimulation
15. MANAGEMENT
PHARMACOTHERAPY FOR AOP
Aminophylline, caffeine and doxapram have been used in the treatment of AOP.
Indications for starting drugs are:
For treatment for apnea of prematurity.
Post extubation to reduce the incidence of apnea.
CAFFEINE
Available for both oral and intravenous
Have advantages over theophylline.
Has a higher therapeutic index so toxicity is less
once-daily dosing is possible due to its longer half life.
Loading dose of 20 mg/kg caffeine citrate( 10 mg/kg caffeine base )
Maintenance dose 5 - 8 mg/kg per dose every 24 hourly
If apnea continues give additional dose of caffeine citrate 10 mg/kg and increase
maintenance dose by 20 %
16. MANAGEMENT
Methylxanthines
Increases MV minute ventilation
improves CO2 sensitivity
enhances diaphragmatic contractility
decreases hypoxic depression of breathing,
decreases periodic breathing.
Mechanism of action :competitive antagonism of adenosine receptors.
Adenosine acts as an inhibitory neuro-regulator in the central nervous system and
is released during hypoxia.
Dose
Loading dose of IV Aminophylline : 5 - 6 mg/kg
Followed by 1.5 to 3 mg/kg every 8 to 12 hours.
Oral theophylline can be administered once the infant becomes stable in the
same dose.
17. MANAGEMENT
DOXAPRAM
IV Doxapram : short term effect (usually not sustained after 48 hours of starting)
So Methylxanthine therapy should be continued during doxapram infusion.
INDICATION :failure to respond to both methylxanthine and CPAP therapy.
DOSE OF INFUSION
Doxapram infusion is started at 0.5 mg/kg/hour
increased gradually to a max of 2.5 mg/kg/hr.
ADVERSE EFFECTS
seizures, hypertension, hyperactivity, hyperglycemia and abdominal distension
should be avoided in the first week of the life or if the serum bilirubin is high
association with intraventricular hemorrhage and kernicterus has been reported.
Injection doxapram has 0.9% benzyl alcohol as a preservative.
The recommended dose of 2-2.5 mg/kg/hr would deliver 21.6-32.4 mg/kg/day of benzyl alcohol.
Although this dose, is below the toxic dose of alcohol (45 mg/kg/day), there have been case reports of
“gasping syndrome” with this lower dose
18. MANAGEMENT
CPAP
used if clinically significant episodes persist despite optimal caffeine therapy
A CPAP of 5cm H2O is usually used.
significantly reduces episodes of obstructive and mixed apneas
attributed to splinting open of the upper airways by the positive airway pressure.
Adverse effects :
1. Barotrauma,
2. Abdominal distension, feeding intolerance
3. Local nasal irritation
NIPPV
If NCPAP in conjunction with a caffeine , is not sufficient to prevent recurring episodes
associated with bradycardia and intermittent hypoxemia, some have suggested use of nasal
intermittent positive pressure ventilation (NIPPV).
NIPPV needed when episodes are related predominantly to central apneas
19. MANAGEMENT
MECHANICAL VENTILATION
both pharmacotherapy and CPAP tried and significant apneas continue to occur.
This method is effective in all forms of apnea.
If the lungs are normal, the infant should be ventilated at
o Minimum pressures
(peak inspiratory pressure of 10-12 cm of water and
positive end expiratory pressure of 3-5 cm of water)
o Low rate (20-25 per minute),
o Short Ti (0.35-0.40 seconds) and
o Low FiO2 (30-50%).
KINESTHETIC STIMULATION
Water bed, oscillating bed mattress.
Evidence does not support any role either in the prevention or treatment of apnea.
20. PERSISTENT APNEA
in some infants Apneic episodes may persist beyond 37-40 weeks
In especially those born before 28 weeks of gestation.
Methylxanthine/Caffeine therapy should be continued if apneic episodes continue to occur
beyond 34 weeks CGA
Re-evaluated baby for secondary causes of apnea especially neurological problems and
gastro-esophageal reflux.
infants would require NICU care until drugs can be weaned and stopped.
Sudden Infant Death Syndrome (SIDS) and Apnea
AOP is not found to be an independent risk factor for SIDS.
Only 2-4% of patients with SIDS have a history of AOP.
