Newborn: Apnea, Hypothermia and Hyperthermia

Dr. Kalpana MallaMD Pediatrics

Manipal Teaching Hospital

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CONTENTS

• Apnea and its types.• Hypothermia• Hyperthermia

APNEA

DEFINITION

• Cessation of breathing for longer than 20sec, or any duration if accompanied by cyanosis and sinus bradycardia

APNEA AND TYPES

• Common in preterm infants : Idiopathic apnea of prematurity

• Associated illness • Periodic breathing • Central apnea• Obstructive apnea• Mixed apnea

OBSTRUCTIVE APNEA

• Absence of identifiable predisposing diseases

• Pharyngeal instability• Neck flexion• Nasal occlusion• Characterized by absent airflow but

persistent chest wall motion • Pharyngeal collapse may follow the

negative airway pressures generated during inspiration, or it may result from incoordination of the tongue and other upper airway muscles involved in maintaining airway patency

CENTRAL APNEA

• Decreased central nervous system (CNS) stimuli to respiratory muscles, airflow and chest wall motion are absent

CAUSES

Central nervous system• Intraventricular

hemorrhage• Drugs • Seizures • Hypoxic injury • Herniation• Neuromuscular

disorders

Infectious• Sepsis• Necrotizing

enterocolitis• Meningitis

Respiratory• Pneumonia • Obstructive airway

lesions • Upper airway collapse• Atelectasis• Extreme prematurity• Phrenic nerve

paralysis• Severe hyaline

membrane disease• Pneumothorax• Hypoxia

CAUSES

Gastrointestinal• Oral feeding • Esophagitis• Intestinal perforation• Gastroesophageal

reflux

Cardiovascular• Hypotension• Hypertension• Heart failure• Anemia• Hypovolemia• Vagal tone

Metabolic• Hypoglycemia• Hypocalcemia• Hyponatremia• Hyperammonemia• Organic acidemia• Hypothermia

Other• Immaturity of

respiratory center• Sleep state

IDIOPATHIC APNEA OF PREMATURITY

• Mixed etiology (50–75%) • Obstructive apnea preceding (usually) or following

central apnea • Short episodes of apnea are usually central,

whereas prolonged ones are often mixed.• Apnea is sleep state dependent • Frequency increases during active (rapid eye

movement) sleep • Paradoxical chest wall movement (inspiratory

abdominal expansion and inward chest wall movement) is common during active sleep and may cause a fall in Pao2 because of ventilation-perfusion defects

• Inhibition of pharyngeal muscle tone during active sleep may contribute to upper airway collapse and obstructive apnea.

CLINICAL MANIFESTATIONS

• The incidence of idiopathic apnea of prematurity varies inversely with gestational age

• preterm : rare on the D1, occurs on D2–D7• Cessation of breathing• Bradycardia • Cyanosis• Apnea of prematurity usually resolves by

36 wk postconceptional age

TREATMENT

• Gentle cutaneous stimulation :mild and intermittent episodes

• immediate bag and mask ventilation : recurrent and prolonged apnea

• Oxygen • Methylxanthines(theophylline or

caffeine) enhance ventilation through a central mechanism or by improving diaphragmatic strength.

TREATMENT (CONTD…)

• Loading doses of 5mg/kg of theophylline (orally) or aminophylline (intravenously)

- followed by doses of 1–2mg/kg given every 6–8hr by the oral or intravenous routes

• Loading doses of 10mg/kg of caffeine - followed 24hr later by maintenance doses

of 2.5mg/kg/24hr qd orally.

• Therapeutic levels: theophylline: 6–10µg/mL; caffeine: 8–20µg/mL

TREATMENT (CONTD…)

• Transfusion of packed red blood cells • Treat gastroesophageal

reflux :antireflux medications controversial

• Nasal continuous positive airway pressure (CPAP)

• Continuous positive pressure splints the upper airway and thereby prevents obstruction.

• Neck extension with a shoulder pad

Hypothermia

Introduction

• After birth, skin temperature falls by 0.3°C/min and core temperature by 0.1°C/min.• 15% of NB develop hypothermia in developing

countries.

Neonatal Considerations

• Relative to body wt, BSA of NB 3 times higher than that of adult.

• LBW insulating layer of s/c fat lesser.• Preterms have less developed stores

of brown fat.

Neonatal Consideratios

• Underdeveloped shivering & sweating mechanisms.

• Limited calorie intake to provide nutrients for thermogenesis.

• Inability to maintain flexed posture in PT to reduce effective surface area.

Response To Cold

• Metabolic thermogenesis- Fetal brown fat laid down in 3rd trimester,

neck, interscapular, axilla, groin, kidney & adrenals.

Local release of noradrenaline-TG oxidised to glycerol & fattyacids-heat.

Loss Of Heat• Radiation-heat dissipates from infant to colder object in environment. Eg wall, window.

• Conduction-heat loss from infant to surface on which baby lies.

• Convection- loss from skin to moving air.

• Evaporation-imply loss of heat by moisture vaporising from skin surface.

Hypothermia• Recording of temperature – Rectal, Axilla, Skin

• Skin temperature <35.5°C

• Core temperature <36°C

• Etiology -excessive heat loss -inability to conserve heat -poor metabolic heat production

Severity of hypothermia

• Cold stress- core temperature 36°C- 35.5°C• Moderate hypothermia 32°C-35.9°C• Severe hypothermia <32°C

Clinical Features• Uncomfortable Restless• Cries to generate heat Sluggish• Inactive Cold, mottled

skin• Bradycardia Low BP• Slow breathing• Poor weight gain,brain growth affected• Low immunity• Hypothermia predisposes to sepsis,

kernicterus etc

How To Keep Babies Warm

• Labour room- prewarmed room, radiant heat source, immediate drying, skin to skin contact with mother, early breast feeding, delay bath.

LBW/PT-transfer to NICU ideally in transport incubator.

• Lying in a ward- next to mother, adequate clothing, saps, sponging/bath.

How To Keep Babies Warm

• Nursery- environ temp maintained at 26 degree C. Prewarm all surfaces in contact with baby. Perspex heat shield, liquid paraffin. Incubator/Open care has manual and servo control modes.

Open Care System

Incubator

How To Keep Babies Warm• Operation theatre-cold ambient environ, prewarm IV

fluids & anesthetic gases, continuous temp monitoring. Humidified oxygen.

• Transport- Uterus ideal transport incubator! Well covered, skin to skin contact. Thermocole box with hot water bottles.

• Home care- Cot away from walls, contact with mother, train to assess temperature, Oil massage

• Kangaroo Mother Care• Biologically controlled heat source• Ventral surface of baby in contact with

mother’s boson• Dorsal surface covered with clothes• Poor cultural acceptability in our society

KANGAROO MOTHER CARE

Prevention of Hypothermia

• Identification of high risk mother• Create warm micro-environment to

welcome the baby• Delay bath• Maintain NICU at 26 degree Celsius• Standby incubator ready• Babies effectively clothed• Special care to prevent Hypothermia during

transport and Procedures

Prevention of Hypothermia

• Application of Oil and Liquid paraffin can reduce evaporation from skin

• Skin to skin contact• Educate mother and health workers

HYPERTHERMIA

• Common in tropical country.• Sunlight exposure for jaundice.• Iatrogenic hypothermia.• PT below 32 wks do not sweat.• Transient fever of newborn- raised environ

temp, immaturity of heat regulating centre, inefficient sweating.

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