PHYSIOLOGY AND MANAGEMENT ON THE HIGH-RISK NEONATE

INTRODUCTION

• Course: Physiology and management of the high-risk neonate
• Presenter: Grace Adjei
• Date: 2/11/2025

LESSON OBJECTIVES

By the end of the lesson, the student should be able to:

• Define Asphyxia Neonatorum.
• Enumerate the causes of Asphyxia Neonatorum.
• Determine the types of the condition and their signs and symptoms.
• Understand the management of the condition.
• Demonstrate neonatal resuscitation.

DEFINITION OF ASPHYXIA NEONATORUM

• Asphyxia: Lack of oxygen.
• Alternate Names: Perinatal asphyxia, neonatal/newborn asphyxia, birth asphyxia.
• Description: Failure of the newborn to initiate and sustain spontaneous respiration leading to deprivation of oxygen.
• Physiological Impact: Results from reduced oxygen or increased carbon dioxide in the body.

CAUSES OF ASPHYXIA NEONATORUM

MATERNAL CAUSES

• Maternal Hypoxia: Insufficient oxygen supply to the mother.
• Maternal Hypotension and Shock: Low blood pressure affecting the mother’s ability to supply oxygen.
• Maternal Hypertension and Vascular Disease: Conditions that affect blood flow during pregnancy.
• Pregnancy Induced Hypertension (PIH): High blood pressure specifically during pregnancy.
• Respiratory Diseases of the Mother: Such as Preterm Birth (PTB).

CONTINUED MATERNAL CAUSES

• Hypertonic Uterine Action: Excessive uterine contractions.
• Prolonged/Obstructed Labor: Difficulty with labor can reduce oxygen delivery.
• Placental Disease: Conditions affecting the placenta, such as syphilitic placenta or dysfunction.
• Effects of Drugs: Such as narcotic drugs or diazepam administered to the mother.
• Severe Anemia: Reduced oxygen-carrying capacity of maternal blood.

FETAL CAUSES

• Obstruction of Airway: By mucus, blood, liquor, or meconium.
• Underdeveloped Lungs: Immature lung development impairs oxygen transfer.
• Postmaturity: Complications due to being overdue.
• Tracheal Atresia: Congenital defect where the trachea fails to develop properly.
• Cord Prolapse and Compression: Umbilical cord issues causing decreased blood flow.
• Congenital Heart Disease: Heart defects affecting circulation.
• Shoulder Dystocia: Difficult delivery affecting breathing.
• Depression of Respiratory Centers: By narcotics or anesthetics given during labor.

APGAR SCORE

The APGAR score assesses the health of the newborn. Each criterion is scored from 0 to 2.

TYPES OF ASPHYXIA NEONATORUM

• Mild or Blue Asphyxia (Asphyxia livida): No significant deprivation of oxygen during labor; primary apnoea.
• Severe or White Asphyxia (Asphyxia pallida): Prolonged oxygen deprivation; circulatory failure leads to shocked appearance; secondary apnoea.

SIGNS AND SYMPTOMS OF ASPHYXIA

MILD ASPHYXIA

• Appearance: Bluish red (deeply cyanotic).
• Pulse: The cord pulsates strongly (60-80 bpm).
• Grimace: Responsive to stimuli (squeezes face).
• Activity: Good muscle tone.
• Respiration: Attempts to breathe; weak cry.
• APGAR Score: Between 5-7.

SEVERE ASPHYXIA

• Appearance: Pale, grey.
• Pulse: The cord pulsates feebly (< 40 bpm).
• Grimace: Limp and unresponsive.
• Activity: Poor muscle tone.
• Respiration: No attempts to breathe; may not cry; in profound shock.
• APGAR Score: Less than 5.

GENERAL PRINCIPLES OF TREATMENT

For management of Asphyxia Pallida:

• Airway Clearance: Ensure the airway is clear.
• Oxygen Administration: Provide oxygen or mouth-bag ventilation.
• Thermal Regulation: Maintain warmth.
• Medical Notification: Inform the physician.
• Combine Interventions: If there’s a poor response, use cardiac massage with artificial respiration.
• Medication as Necessary: Administer drugs where indicated.
• Continuous Monitoring: Observe the baby’s condition closely.

ASSESSING APGAR IN UTERO

• Fetal Heart Rate Monitoring: Essential to detect compromise.
• Meconium-Stained Liquor: Observed in cephalic presentation.
• Fetal Movement: Excessive movement may indicate distress.
• Fetal Blood Sampling: Can confirm fetal acidosis.

PREPARATION FOR ASPHYXIATED BABY

• Expectant measures necessary for potential asphyxia.
• Ready Resuscitation Equipment: Always available and functional.
• Knowledgeable Personnel: Staff must be familiar with equipment and resuscitation techniques.

RESUSCITATION EQUIPMENT REQUIRED

• Resuscitaire with overhead radiant heater.
• Clock timer for timing interventions.
• Two straight-bladed infant laryngoscopes.
• Neonatal endotracheal tubes.
• Neonatal airways.
• Suction catheters for airway clearance.
• Neonatal bag and mask for ventilation.

ADDITIONAL RESUSCITATION EQUIPMENT

• Endotracheal tube introducer.
• Magills forceps for airway management.
• Syringes for medication administration.
• Stethoscope for auscultation.
• Cord clamps for umbilical cord management.
• Drugs for emergency treatment (e.g., epinephrine, sodium bicarbonate).
• Warmed dry towels for surface warming.
• Adhesive tape for tube fixation.

MANAGEMENT OF ASPHYXIA NEONATORUM

AIMS OF RESUSCITATION

• Establish and maintain a clear airway through ventilation and oxygenation.
• Ensure effective circulation.
• Correct metabolic acidosis.
• Prevent related complications such as hypothermia, hypoglycemia, and hemorrhage.

INITIAL STEPS IN RESUSCITATION

1. Start a clock immediately upon delivery.
2. Assess APGAR score at 1 minute.
3. Commence resuscitation if there's no respiratory effort.
4. Clear airway via gentle suctioning of oro- and nasopharynx, while verifying heartbeat.

FOLLOW-UP MANAGEMENT STEPS

• Drying and Warming: Rapidly dry the infant, cover with a prewarmed blanket.
• Positioning: Place the infant on a flat, firm surface with slight head extension to keep airway open.

STIMULATION TO INITIATE BREATHING

• Gentle drying and airway clearance may provoke breathing.
• Methods include flicking the baby’s foot or gentle rubbing.
• Use low-flow oxygen (2-4 L/min) to stimulate gasping.

AIRWAY CLEARANCE

• In most cases, airway clearance is not required at birth; however, suction may be necessary if respiratory distress is apparent.
• Suction catheter should be limited to 5 cm and each attempt should not exceed 5 seconds.
• In the presence of thick meconium, suctioning should be done under vision, leveraging a laryngoscope.

VENTILATION AND OXYGENATION

• Assisted ventilation may be required if the infant does not respond to airway clearance.
• Methods of Assisted Ventilation:
    - Neonatal Bag and Mask: A mask is carefully fitted over the infant’s mouth and nose. Air is delivered using a bag with a self-limiting pressure valve.
    - Airway Management: The baby’s jaw must be held forward, and sustained inflations (five at a pressure of 30 cmH2O for 2-3 seconds) should be administered followed by continued ventilation at 40 respirations/min.

ENDOTRACHEAL INTUBATION

• If there is no response to assisted ventilation via bag and mask, and bradycardia is noted, intubation is necessary without delay.

MOUTH-TO-FACE RESPIRATION

• If specialized equipment is unavailable, mouth-to-face resuscitation can be performed by covering the infant’s mouth and nose with the operator’s mouth, delivering gentle breaths at 20/min old.

EXTERNAL CARDIAC MASSAGE

• Indicated when heart rate falls below 60 bpm or is between 60-100 and decreasing despite ventilation.
• Technique involves encircling the chest with the fingers, thumbs placed on the lower third of the sternum.
• Compression rate: 100-120 per minute, at a ratio of 3:1 compressions to breaths, with a depth of one-third of the chest (1.5-2.0 cm).
• Check periodically for color, perfusion, and heart rate.

PHARMACOLOGICAL INTERVENTIONS

• If the baby exhibits slow responses post-resuscitation, consider using drugs:
    - Naloxone Hydrochloride: To reverse effects of maternal narcotics given in the past 3 hours; dose: 0.1-0.2 mg/kg body weight IM.
     - Caution: Do not administer to babies of narcotic-addicted mothers.
    - Sodium Bicarbonate: For continued heart rates below 60 bpm; administer 2-4 ml/kg of a 4.2% solution slow IV, rate 1 ml/min.
    - Epinephrine (Adrenaline): If heart rate remains below 60 bpm despite effective ventilation; initial dose of 0.1-0.3 ml/kg of 1:10000 solution IV.
    - Calcium Gluconate and Isoprenaline: Used for severe bradycardia or cardiopulmonary arrest (doses vary).
    - Human Albumin: To manage pulmonary hemorrhage or shock; administer 10-20 ml/kg.
    - Dextrose (10%): To address hypoglycemia.
    - Konakion (Vitamin K): To minimize hemorrhage risk; up to 1 mg IM.
    - Dexamethasone: To reduce cerebral edema risk in severe asphyxia; 1-2 mg IV or IM.

OBSERVATION AND AFTERCARE

• Throughout the resuscitation process, monitor and record the infant’s response closely.
• Document when spontaneous respiration resumes.
• An endotracheal tube may be retained for several minutes post spontaneous breathing onset.
• Infants with an APGAR score below 6 at 5 minutes or slow responsiveness should be transferred to the neonatal unit for monitoring of cerebral function.
• Explain the situation and needed transfer to the parents. Allow mother to see and hold the baby if conditions permit. Quick responders can remain with parents post-delivery until normal transfer to the postnatal ward.

RESUSCITATION ACTION PLAN

Key Points of Resuscitation:

• Anticipate potential complications.
• Verify readiness of resuscitation equipment.
• Start a timer upon delivery.
• Perform required suctioning.
• Maintain warmth throughout.
• Regularly assess APGAR scores.
• Ensure oxygen delivery.
• Implement bag and mask ventilation.
• Consider endotracheal options if necessary.
• Administer cardiac massage as needed.
• Utilize pharmacological interventions when indicated.
• Address any additional problems as they arise.

CONCLUSION

• This outlines the critical aspects of understanding, diagnosing, and managing Asphyxia Neonatorum, equipping healthcare professionals to handle newborn respiratory distress effectively.

QUESTIONS AND DISCUSSIONS

• Open floor for any queries or additional contributions.