45-Fetal & Neonatal Asphyxia

FETAL & NEONATAL FETAL & NEONATAL ASPHYXIAASPHYXIA

DEFINITIONDEFINITION

Fetal asphyxia is a state of Fetal asphyxia is a state of inadequate oxygenation and inadequate oxygenation and inadequate elimination of CO2, which inadequate elimination of CO2, which if allowed to be continued, will result if allowed to be continued, will result in metabolic acidemia (umbilical in metabolic acidemia (umbilical arterial blood pH < 7.2).arterial blood pH < 7.2).

PATHOPHYSIOLOGYPATHOPHYSIOLOGY

The fetal respiratory centers in the The fetal respiratory centers in the medulla are inhibited by higher medulla are inhibited by higher centers in the diencephalon. centers in the diencephalon.

The mild temporary anoxia at birth The mild temporary anoxia at birth (due to stoppage of the placental (due to stoppage of the placental circulation) depresses the higher circulation) depresses the higher cortical centers, thus releasing the cortical centers, thus releasing the medullary centers from inhibition. medullary centers from inhibition.

PATHOPHISIOLOGYPATHOPHISIOLOGY

The medullary centers become The medullary centers become stimulated by:stimulated by:

a.a. Sensory stimuli from the skin, Sensory stimuli from the skin, muscles & joints; muscles & joints;

b.b. Relative increase in carbon Relative increase in carbon dioxide concentration dioxide concentration (chemoreceptors) (chemoreceptors)

c.c. Rise in blood pressure at birth Rise in blood pressure at birth (pressor receptors).(pressor receptors).

PATHOPHYSIOLOGYPATHOPHYSIOLOGY

However, if the anoxia is marked or However, if the anoxia is marked or prolonged, the lower respiratory centers prolonged, the lower respiratory centers in the medulla together which the in the medulla together which the vasomotor centers become paralyzed vasomotor centers become paralyzed leading to asphyxia & shock. leading to asphyxia & shock.

Thus, if prompt resuscitation is not done Thus, if prompt resuscitation is not done at an early stage, the irreversible at an early stage, the irreversible damage to the respiratory center will damage to the respiratory center will result in failure of all attempts at result in failure of all attempts at recovery.recovery.

ONSET of ONSET of RESPIRATION(causes)RESPIRATION(causes)

Mild temporary anoxia at birth (due to Mild temporary anoxia at birth (due to stoppage of placental circulation), which stoppage of placental circulation), which depresses higher cortical centers thus depresses higher cortical centers thus releasing medullary centers from inhibition.releasing medullary centers from inhibition.

Physical stimulation: afferent sensory Physical stimulation: afferent sensory stimuli from the skin, muscles & joints.stimuli from the skin, muscles & joints.

The compression of the fetal thorax incident The compression of the fetal thorax incident to vaginal delivery & the expansion that to vaginal delivery & the expansion that follows delivery may be an auxiliary factor follows delivery may be an auxiliary factor in the initiation of respiration. in the initiation of respiration.

Aetiology of Intrauterine fetal Aetiology of Intrauterine fetal distress (asphyxia)distress (asphyxia)

I - MATERNAL CAUSES:I - MATERNAL CAUSES: (conditions (conditions leading to imperfect oxygenation of leading to imperfect oxygenation of maternal blood)maternal blood)

Severe anemia, Hemorrhage & Severe anemia, Hemorrhage & shock, Respiratory failure, and shock, Respiratory failure, and heart failure.heart failure.

Eclamptic convulsions, advanced Eclamptic convulsions, advanced pulmonary T.B., pneumonia, and pulmonary T.B., pneumonia, and pulmonary edema. pulmonary edema.

Aetiology of intrauterine Aetiology of intrauterine asphyxia ( cont….)asphyxia ( cont….)

II- PLACENTAL CAUSES:II- PLACENTAL CAUSES: Placental compression: interfering with its Placental compression: interfering with its

circulation as in tonically contracted circulation as in tonically contracted uterus, prolonged labour after rupture of uterus, prolonged labour after rupture of the membranes or as a method of control the membranes or as a method of control of bleeding in placenta previa.of bleeding in placenta previa.

Placental separation as in accidental Placental separation as in accidental hemorrhage.hemorrhage.

Placental insufficiency e.g. extensive Placental insufficiency e.g. extensive degeneration, multiple infarcts & degeneration, multiple infarcts & abnormally small placenta.abnormally small placenta.

Aetiology (cont…)Aetiology (cont…)

III- CAUSES IN THE UMBILICAL CORD:III- CAUSES IN THE UMBILICAL CORD: Obstruction of the circulation, which may Obstruction of the circulation, which may be due to:be due to:

Tight coils around the neck.Tight coils around the neck. True knots of the cord.True knots of the cord. Prolapsed cord.Prolapsed cord. Compression of the vessels by haematoma Compression of the vessels by haematoma

of the cord or by blades of the forceps.of the cord or by blades of the forceps. Rupture of vasa praevia.Rupture of vasa praevia.

Aetiology ( cont…)Aetiology ( cont…)

IV-PROLONGED COMPRESSION OF THE IV-PROLONGED COMPRESSION OF THE FETAL HEAD:FETAL HEAD:This will cause edema and ischemia, which This will cause edema and ischemia, which interfere with the blood supply of the interfere with the blood supply of the medulla leading to depression of the medulla leading to depression of the respiratory center. Prolonged compression respiratory center. Prolonged compression may be due to:may be due to:

Contracted pelvis (C/P disproportion).Contracted pelvis (C/P disproportion). Rigid perineum.Rigid perineum. Intracranial hemorrhage.Intracranial hemorrhage. Forceps application for a long time.Forceps application for a long time. Depressed fracture Depressed fracture

CLINICAL FEATURESCLINICAL FEATURES

1-F.H.R. >160 (tachycardia), or <100 1-F.H.R. >160 (tachycardia), or <100 (bradycardia, which is more (bradycardia, which is more dangerous) or irregular.dangerous) or irregular.

2-Delay of return of the FHR to their 2-Delay of return of the FHR to their normal rate after uterine normal rate after uterine contraction. (FHR normally slows contraction. (FHR normally slows down during the uterine down during the uterine contraction, and returns rapidly to contraction, and returns rapidly to normal after it ends).normal after it ends).

Clinical features Clinical features

3-If continuous electronic monitoring of the 3-If continuous electronic monitoring of the fetal heart rate and uterine contractions is fetal heart rate and uterine contractions is available, the following criteria would available, the following criteria would suggest fetal distress:suggest fetal distress:

a-Late deceleration (see assessment of fetal a-Late deceleration (see assessment of fetal well being).well being).

b-Variable deceleration.b-Variable deceleration.

C-Loss of beat-to-beat variation in fetal heart C-Loss of beat-to-beat variation in fetal heart rate.rate.

d-A sinusoidal fetal heart rate pattern.d-A sinusoidal fetal heart rate pattern.

Clinical features Clinical features

3-Passage of meconium in cephalic 3-Passage of meconium in cephalic presentations, due to relaxation of presentations, due to relaxation of the anal sphincter due to anoxia & the anal sphincter due to anoxia & intestinal peristalsis.intestinal peristalsis.

4-Fetal acidosis: Detected by taking 4-Fetal acidosis: Detected by taking blood samples from the scalp of the blood samples from the scalp of the fetus during labour; pH below 7.2 fetus during labour; pH below 7.2 indicates fetal asphyxia (N. 7.25- indicates fetal asphyxia (N. 7.25- 7.35).7.35).

MANAGEMENT OF MANAGEMENT OF INTRAUTERINE ASPHYXIAINTRAUTERINE ASPHYXIA

Try to eliminate the cause if possible:Try to eliminate the cause if possible: The patient should be turned onto her side: this The patient should be turned onto her side: this

may relieve either umbilical cord compression, may relieve either umbilical cord compression, or alleviate poor return of blood to maternal or alleviate poor return of blood to maternal heart caused by occlusion of the maternal aorta heart caused by occlusion of the maternal aorta or IVC by the gravid uterus.or IVC by the gravid uterus.

Oxytocin infusion, if started, should be Oxytocin infusion, if started, should be discontinued to _ uterine activity & improve discontinued to _ uterine activity & improve placental perfusion.placental perfusion.

Any hypotension should be corrected by Any hypotension should be corrected by position change, intravenous hydration or position change, intravenous hydration or vasopressor treatment if severe hypotension vasopressor treatment if severe hypotension due to induction anesthesia develops due to induction anesthesia develops

ManagementManagement

2-Oxygen (100%)2-Oxygen (100%) should be administered should be administered to the mother by facemask.to the mother by facemask.

3-Atropine3-Atropine given to the mother may be given to the mother may be beneficial in some cases of fetal beneficial in some cases of fetal bradycardia.( of no proven value )bradycardia.( of no proven value )

4-If the situation improves, careful follow 4-If the situation improves, careful follow up; preferably by the aid of electronic up; preferably by the aid of electronic fetal monitoring is essential.fetal monitoring is essential.

ManagementManagement

5-If fetal distress is not relieved within 5-If fetal distress is not relieved within several minutes, immediate delivery several minutes, immediate delivery is indicated. Vaginal examination is is indicated. Vaginal examination is done to detect degree of cervical done to detect degree of cervical dilatation, presentation, position & to dilatation, presentation, position & to rule out cord prolapse & rule out cord prolapse & the fetus is the fetus is delivered bydelivered by: :

Breech extraction or forceps if the Breech extraction or forceps if the cervix is fully dilated. cervix is fully dilated.

C.S., if cervix is not fully dilated.C.S., if cervix is not fully dilated.

CAUSES OF POSTNATAL ASPHYXIA CAUSES OF POSTNATAL ASPHYXIA

(ASPHYXIA NEONATORUM(ASPHYXIA NEONATORUM

1-Persistence of a state of severe 1-Persistence of a state of severe intrauterine asphyxia after birth. intrauterine asphyxia after birth.

2-Obstruction of respiratory passages 2-Obstruction of respiratory passages by mucus, amniotic fluid, blood or by mucus, amniotic fluid, blood or meconium.meconium.

3-Paralysis of cardiorespiratory 3-Paralysis of cardiorespiratory centers, due to cerebral centers, due to cerebral hemorrhage.hemorrhage.

Cont…Cont…

4-Depression of the respiratory centers by 4-Depression of the respiratory centers by drugs (morphine or pethidine) or drugs (morphine or pethidine) or narcotics & anesthetics given during narcotics & anesthetics given during labour.labour.

5-Congenital malformations: e.g. congenital 5-Congenital malformations: e.g. congenital atelectasis of the lungs or congenital atelectasis of the lungs or congenital abnormality in respiratory or circulatory abnormality in respiratory or circulatory system.system.

6-Prematurity (R.D.S.).6-Prematurity (R.D.S.).

7-Congenital debility.7-Congenital debility.

CLINICAL FEATURES OF CLINICAL FEATURES OF ASPHYXIA NEONATORUM:ASPHYXIA NEONATORUM:

# With initial oxygen deprivation the # With initial oxygen deprivation the new born develops rapid breathing new born develops rapid breathing pattern followed by a period of APNEA. pattern followed by a period of APNEA. .: .:

# # ClinicallyClinically, , primaryprimary and secondary and secondary apnea, are indistinguishable.apnea, are indistinguishable.

The older classification of asphyxia The older classification of asphyxia neonataorum into neonataorum into asphyxia Lividaasphyxia Livida and and asphyxia Pallidaasphyxia Pallida has been abandoned has been abandoned and is nowadays considered obsolete.and is nowadays considered obsolete.

Postnatal asphyxia Postnatal asphyxia

Primary apnea:Primary apnea: It represents the It represents the initial phase of apnea initial phase of apnea

Secondary apnea: Secondary apnea: If oxygen If oxygen deprivation persists deprivation persists

CLINICAL ASSESSMENT CLINICAL ASSESSMENT (APGAR SCORE)(APGAR SCORE)

Virginia Apgar (1953)In this Virginia Apgar (1953)In this system the child’s condition is system the child’s condition is assessed one minute and five assessed one minute and five minutes after birth utilizing minutes after birth utilizing five featuresfive features

APGAR score APGAR score

1.1. AAppearance (color)ppearance (color) 2.2. PPulse (heart rate)ulse (heart rate) 3.3. GGrimace (reflex irritability)rimace (reflex irritability) 4.4. AActivity (muscle tone)ctivity (muscle tone) 5.5. RRespiration (respiratory effort)espiration (respiratory effort)

Either 0, 1 or 2 is given for each clinical Either 0, 1 or 2 is given for each clinical feature and a total degree out of ten feature and a total degree out of ten is given for the 5 clinical features.is given for the 5 clinical features.

Apgar score should be done at one and Apgar score should be done at one and 5 minutes after birth5 minutes after birth

1.1. One minute Apgar score: One minute Apgar score: determines the need for immediate determines the need for immediate resuscitationresuscitation

2.2. Five minutes Apgar score is Five minutes Apgar score is useful index of the effectiveness of useful index of the effectiveness of resuscitation methods, when low is resuscitation methods, when low is indicative of infant at higher risk of indicative of infant at higher risk of morbidity and mortality (prognostic)morbidity and mortality (prognostic)

IMPORTANCEIMPORTANCE

1.1. One minute Apgar score: One minute Apgar score: determines the need for immediate determines the need for immediate resuscitationresuscitation

2.2. Five minutes Apgar score is Five minutes Apgar score is useful index of the effectiveness of useful index of the effectiveness of resuscitation methods, when low is resuscitation methods, when low is indicative of infant at higher risk of indicative of infant at higher risk of morbidity and mortality (prognostic)morbidity and mortality (prognostic)

MANAGEMENT OF ASPHYXIA MANAGEMENT OF ASPHYXIA NEONATORUMNEONATORUMPROPHYLAXIS:PROPHYLAXIS:

1. 1. Proper antenatal careProper antenatal care for for detection and proper management of detection and proper management of probable cause of intrauterine probable cause of intrauterine asphyxia.asphyxia.

Management ( prophylaxis)Management ( prophylaxis)

2. 2. Proper intranatal care:Proper intranatal care: Careful observation of FHR.Careful observation of FHR. Avoid operative trauma (forceps)Avoid operative trauma (forceps) Avoid morphia within 3 hours before Avoid morphia within 3 hours before

laborlabor Proper oxygenation during Proper oxygenation during

anesthesiaanesthesia

Cont..Cont..

Episiotomy is strongly recommended Episiotomy is strongly recommended especially for breech and premature especially for breech and premature infants.infants.

Proper delivery of the after coming headProper delivery of the after coming head Vitamin K for all premature and breech Vitamin K for all premature and breech

deliveriesdeliveries Aspiration of the mucus and meconium Aspiration of the mucus and meconium

from fetal larynx before it starts from fetal larynx before it starts breathing.breathing.

ACTIVE MANAGEMENT ACTIVE MANAGEMENT (ACTIVE RESUSCITATION(ACTIVE RESUSCITATION

Resuscitation of the new born is an Resuscitation of the new born is an excellent example of a excellent example of a team workteam work that that needs cooperation and harmony between needs cooperation and harmony between each member, namely the obstetrician, each member, namely the obstetrician, the neonatologyst, the anaesthesiologyst the neonatologyst, the anaesthesiologyst and the nursing team.and the nursing team.

The The first few minutes first few minutes in the new born's in the new born's life may be crucial in determining both its life may be crucial in determining both its potential for survival and its future health potential for survival and its future health performance which may not be revealed performance which may not be revealed except after several months or even except after several months or even

Active managementActive management

1-Clearing the air passages:1-Clearing the air passages: Holding the Holding the infant from the feet and aspirating mucus infant from the feet and aspirating mucus from the mouth and upper pharynx by a from the mouth and upper pharynx by a rubber catheter.rubber catheter.

N.B.:N.B.: The infant's head should The infant's head should not be lowered if intracranial not be lowered if intracranial hemorrhage is suspected.hemorrhage is suspected.

1-Warming the infant:1-Warming the infant:Warming is Warming is necessary to decrease oxygen necessary to decrease oxygen requirements and to avoid attacks of requirements and to avoid attacks of apnea.apnea.

Active ManagementActive Management

3-Oxygen therapy : 3-Oxygen therapy : When necessary, may When necessary, may be supplied bybe supplied by::

Small mask or stream in front of the Small mask or stream in front of the mouth and nose (O2 saturation …).mouth and nose (O2 saturation …).

Endotracheal tube is indicated if:Endotracheal tube is indicated if:– 1 minute Apgar score < 31 minute Apgar score < 3– Persistent Apnea.Persistent Apnea.– Persistent Bradycardia < 100.Persistent Bradycardia < 100.

4-Artificial respiration: by:4-Artificial respiration: by:

Endotracheal tube with intermittent Endotracheal tube with intermittent positive pressure insufflation positive pressure insufflation

Mouth to mouth breathing until Mouth to mouth breathing until endotracheal tube is available.endotracheal tube is available.

Active ManagementActive Management

5-Cardiopulmonary resuscitation:5-Cardiopulmonary resuscitation:

Cardiac resuscitation together with Cardiac resuscitation together with Endotracheal entubation (or mouth to Endotracheal entubation (or mouth to mouth breathing)mouth breathing)– No audible heart beats or No audible heart beats or – Heart rate < 100. Heart rate < 100. – Thumbs are put at the junction of lower and Thumbs are put at the junction of lower and

middle 1/3 of sternum to compress the chest middle 1/3 of sternum to compress the chest gently 100 times per minute.gently 100 times per minute.

Active ManagementActive Management

6-Use of Drugs:6-Use of Drugs: Nalorphine:Nalorphine: ½ mg into umbilical vein if ½ mg into umbilical vein if

asphyxia is due to morphia.asphyxia is due to morphia. Sodium bicarbonate 8.4%:Sodium bicarbonate 8.4%: If the infant If the infant

develops acidosis with severe asphyxia.develops acidosis with severe asphyxia. Epinephrine:Epinephrine: May be used for cardiac May be used for cardiac

resuscitation (if absent heart beats). resuscitation (if absent heart beats). Up to 0.5 cc are injected either into Up to 0.5 cc are injected either into umbilical umbilical

veinvein or or intracardiac intracardiac Antibiotics:Antibiotics: To prevent pneumonia To prevent pneumonia

especially if resuscitation has been difficult.especially if resuscitation has been difficult.