Any newborn who does not estabilshment spontaneous respiration should be assisted immediately or hypoxia and acidosis will ensue. About 35% of all death during the first year of life occur within the first 24 hours and half of these are related to anoxia and pulmonary pathology(3).
Cardiopulmonary resuscitation is concerned with restoration of pulmonary,cardiovascular and neurologic function. Firstly it consist of artificial respiration and circulation by whatever means is immediately available to prevent clinical death from progressing to biological death.(4)
Cardiopulmonary function can be restored more readily in children than in the adult. If the heart arrest before the moment of delivery cardiac massage probably better avoided since neural damage may well occur in the unknown interval elapsing before the circulation can be restarted.(2)
In addition resuscitation may actually be started before birth for the anesthetist can do much to mitigate or avoid the intrapartum asphyxia which plays a large part in many cases of depression and death of the newborn(Buttler 1963) (e.g.adequate preoperative transfusion,avoidance hypoxia at all time provision with short induction delivery interval).(2)
Diabetic mothers and premature babies prone to have hyaline membrane disease or respiratory distress syndrome (RDS),it responsible for some 30% of neonatal fatalities in certain centers(Brown 1959) (2)
FACTORS CONTRIBUTING TO NEONATAL RESPIRATORY DEPRESSION(2):
These may be broadly devided into two categories (Cook 1958)
1. Failure in function of the central nervous mechanism
much often due typoxia or drug depression.
2. Failure in response of the peripheral respiratory
structure.
Further breakdown reveals the common predisposing factors in neonatal asphyxia each leading ultimately to one or other of the two main causes of depression.
a.Developmental :
i.hypoplasia of the lungs,choanal atressia etc.
ii.other fetal abnormalities
iii.prematurity
iv.post maturity
b. Maternal causes :
i diabetes v prolapsed cord
ii toxaemia vi cord compression
iii hypertension vii placental separation
iv hypotension or hypoxia viii hypertonic uterus
c. Trauma to fetus at birth :
i long labor iv instrumental delivery
ii precipitate labor v breech delivery
iii disproportion
d. Drugs : Analgesia/anesthesia
e. Maternal hyperventilation during anesthesia
f. i Airway obstruction due to mucus, meconium etc.
ii Respiratory distress syndrome (hyaline membrane
disease)
HAZARDS OF SPECIAL PEDIATRIC SIGNIFICANCE.( 4)
Anesthesiologist should be constantly be aware that factors which may insignificant in the adult may be life threatening in small children.
At anytime the upper airway may become obstructed by :
1.Small amount of mucus
2.Hypertrophie adenoid tissue
3.The relative large tongue,ascociated with:
a.Flaccidity resultant upon unconciousness.
b.In advertent displacement of submental soft tissue and
tongue by anesthesiologist's fingers.
c.Inadequate extension or over extension in infant.
d.Inadequate elevation of jaw.
e.Premature removal of artificial airway.
4.Regurgitation is a common occurence because of
frequency of feedings.
5.The infant stomach is readily inflated by:
a. Too high inflation pressure
b. Partial obstruction of airway.
Remember,infants are primary nose breather,if the nasal airway is inadequate an oral airway should be inserted.(3)
In the infants/neonates the upper airway predispossed to obstruct due to narrow passage of the nose,glottis,trachea and the presence of lymphoid tissue (3)
When there is airway obstruction,substernal,suprasternal and intercostal retraction are more marked both in older children and when dyspnoe is severe.
In the very young child these signs must be looked for very carefully if obstruction is to be recognized early.(3)
Infant and children require larger amount of oxygen due to an increased metabolic rate.
EVALUATION:(1)
A. Fetal monitoring
1.Electronic fetal monitoring of both fetal heart rate and
intra uterine pressure provides information valuable to
predicting which infants will be depressed at birth.
2.Type II or late deceleration patterns of fetal heart rate
are ascociated with fetal hypoxia and may respond to a
change of maternal position or to the administration of
fluids and oxygen.
At delivery infants who have had persistent type II
decelaration tend to be depressed.
3.Other ominous fetal heart rate patterns such as
fixed,non varrying bradycardia or lost of baselin
variability (in tha absence of atropine or diazepam given
to the mother) are also ascociated with the births of
depressed infants.(1).
B.NEWBORN ASSESSMENT :
Assessment depends on the rapid evaluation of a few
fundamental sign of normal or depressed tissue oxygen and
this should be carried out as soon as possible after
delivery.
1. Depression in the newborn is usually due to one of three
factors :
-uteroplacental insufficiency
-maternal medicales
-neonatal disease
The infants should be assessed from the view points of :
a. Respiratory activity : Ventilation may be depressed
centrally from maternal drugs(eg.narcotic),severe
acidosis or infections.
May also be affected by alveolar collapse as in
RDS,blockage of air passages with meconium or by
aspiration of blood. Finally,mechanical interference with
breathing maybe caused by diaphragmatic hernia or
pneumothorax.
b Cardiac output may be impaired by hemorrhage,hypoxia
acidosis or congenital cardiac anomalies.
2 Integrity of the newborn has claissically been assessed
using the Apgarscore Apgar scoring methode is numerical
index of the aviability of a newborn at 1 and 5 minutes
after completion of childbirth, Two points are alloted for
each of five clinical signs (a maximum score being 10) and
assessment is made at 1 and 5 minutes after birth.
The signs evaluated are :
A = Appearance : Is the infant pink or blue ?
Two points are alloted for a totally pink infants.One
point is given to the infant with acro cyanosis and no
points are given to the cyanotic infants.
P = Pulse
Two points are given for a heart rate greater than 100,
One point for heart rate less than 100. If there is no
spontaneous heart activity,no point are scored.
This is the most important single sign in assessment and
resuscitation (Brown 1954) emphasized this pointing
out that although the newborn are tolerant of
hypoxia,tolerance of ischemia is no better than in
adult.Severe hypoxia may be readily treated,but the
presence of circulation failure at once makes the
outcome doubtful.
G= Grimace of reflex irritability :
Two points are given for a vigorous cry in response to
oral suctioning. One point is given for a weak cry or
some motion, and no points are scored if response is
totally lacking.
This often elicited by use of the sucker which may
produce grimacing, coughing or sneezing.
A widely used reflex stimulus is a slap to soles of the
feet which will often causes flexion withdrawal and
crying.
Failure response in the depressed infant after this
manouvres should not call for futher assault.
A = Activity of muscle tone :
The well oxygenated infant has good tone at birth.
Increasing asphyxia leads to a progressive loss of tone
and eventually flaccidity.
Two points are given for good muscle tone,the infants
drawing himself into the flexed position. One point is
given when there is some flexion of extrimities but no
points are scored when the infant is flaccid.
R = Respiratory effort
Apnoe may occur, perhaps after one or two initial gasp
or without any respiratory efforts being made at all.
Two points are given for regular respiratory efforts
one,one for irregular respiration and none in the
absence of spontaneous respiration.
A score 0 to 10 is assigned for each of these five evaluations. The neonates scoring 7 or above is considered in good conditions.
The score of 4 to 6 he is moderately depressed (requires some attention).
If the score less than 4,the neonate is considered seriously depressed, demand major resuscitative intervension (1,3).
Apgar rating at 5 minutes reflects the result of the resuscitative efforts and provides an index of the value of further efforts (3).
The non depressed infant approaches delivery with a mild respiratory and metabolic acidosis,his pH in the range of 7,25 -7.30 with PaCO2 of about 45 mmHg(3).
Following delivery all infants show a transient decrease in pH and increase base deficit, these alteration reaches a maximum at 4 minutes of life.
This mild acidosis in normal term infant does not need to be treated.
An infant with Apgar score of 7 or greater tends to correct its pH by the end of one hour, at which point the pH approaches 7.35.The PaCO2 is likely to be between 35 and 40 mmHg.
The infant with an Apgar score of 6 or less is relatively more acidotic than his counterpart with a score of 7 or more acidosis. The acidosis is both respiratory and metabolic acidosis but metabolic acidosis develops slowly during cardiac arrest and CPR in both animals and humans.
In depressed infants the pH during labor may run from 7.15 to 7,25 and the base deficit may approach 10 meq/L,the PaCO2 ranges from 40 to 55 mmHg.
In the markedly premature infant, surfactant production and even pulmonary blood flow can be reduced by acidosis (1).
Therefore the acidosis of the depressed all premature infants is treated immediately in the delivery room. But the priority is to treat respiratory acidosis with ventilation and oxygenation and metabolic acidosis is treated when severe because hypernatremia and hyperosmolarity cause by bicarbonat natricus administration during and following CPR and ascociated with a poor outcome (Mattar et al 1974).(7)
To Be Continued
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