The Newborn Baby





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NEONATAL APNOEA



A relatively high negative pressure is required to overcome lung resistance to expansion, but lung compliance increases thereafter, and progressively less effort is needed. The first breath is all-important, and if it does not occur within one minute of delivery a state of apnoea is considered to exist.


DEGREES OF APNOEA



1. Primary Apnoea


Cyanosed, with some muscle tone and a heart beat over 100. Efforts at breathing are made and gasping occurs.


2. Secondary Apnoea


This is sometimes called terminal apnoea because if not soon corrected brain damage or death will follow. The skin is greyish-white, there is no muscle tone and the heart beat is less than 100. There is associated hypotension which is poorly tolerated by the newborn infant.

It is often difficult in practice to decide on the degree of apnoea, especially when drug-induced depression is present.


CAUSES OF APNOEA



Antenatal


Any condition leading to fetal hypoxia, such as placental insufficiency, pre-eclampsia, placental abruption.


Intrapartum


Prolonged hypoxic labour, traumatic delivery, opiate drugs, anaesthesia. (Even epidural anaesthesia if prolonged.)


Postnatal


Immaturity, cerebral trauma, congenital abnormalities such as diaphragmatic hernia.




APNOEA — RESUSCITATION



The first sign or recovery is a quickening and strengthening of the fetal heart, followed by attempts at respiration and improved colour. Once the baby is breathing spontaneously, consideration should be given to transfer to a special nursery.



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It may be necessary to employ IPPV for up to 20 minutes before respiration becomes spontaneous, or death is recognised as inevitable.


OTHER MEASURES



Cardiac Massage


If the heart rate falls below 80, rhythmic compression should be applied over the sternum, at the rate of about 5 compressions to one inflation of the lungs.


Acidosis


This seldom requires correction once adequate ventilation is established, but in cases of severe asphyxia a combination of plasma volume expansion (normal saline or plasma protein solution) and, very occasionally, judicious infusion of a 0.5 molar solution (4.2%) sodium bicarbonate in 10% dextrose (2ml per kg) may be employed. This may be given via the umbilical vein after insertion of an umbilical catheter.


Hypothermia


An apnoeic baby loses heat very quickly, especially if it is immature and the recommended labour room temperature of 25°C is too low. Local heat must be provided by warm towels and preferably by an overhead radiant heater attached to the resuscitation trolley.


Drugs


Occasionally there may be a place for adrenaline (epinephrine) 1:10000, 1 ml in severe bradycardia or cardiac asystole.


HEAT LOSS IN THE NEWBORN





Heat Production





1. Energy from diet.


2. Metabolic activity mainly in the muscles. (Babies have no protective shivering reflex.)


3. Breakdown of fat. Fat in certain areas such as between the shoulder blades and the perirenal capsule (brown fat) can be catabolised very quickly.


Heat Loss from the Skin





1. Radiation.


2. Evaporation from wet skin exposed to air.


3. Convection.


4. Conduction.

Small amounts of heat are lost through respiration and in urine and faeces.


Clinical Features of Hypothermia (cold injury)


This is rare and avoidable.

The baby is difficult to rouse, cold to touch, lethargic and unwilling to feed. There is oedema of the hands and feet and eyelids and a hardening of the subcutaneous tissues (sclerema). The redness of cheeks and extremities and the absence of crying give a misleading appearance of healthiness. As the metabolism slows down, the baby becomes hypoglycaemic and death occurs.



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Note oedema of face. Shaded areas represent redness and subcutaneous sclerema.


Treatment


Hypothermia is very difficult to reverse, and the only effective treatment is complete prevention.


1. The labour room temperature should be above 25°C.


2. All resuscitative procedures should be carried out under an infra-red heater.


3. The baby should be dried at birth and covered with a dry towel. It must be well wrapped up if it is staying in the ward.


4. If transfer to a special care baby unit (SCBU) is necessary this must be done in a heated cot. Once in an incubator the paediatrician’s object is to maintain the baby’s temperature at 37°C, and very small babies may require an ambient temperature as high as 37°C.



ROUTINE SCREENING TESTS





PKU IN THE BABY


Every baby is screened by the Guthrie test which demonstrates abnormal blood levels of PH after feeding is well established (5–10 days).



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The paper disc impregnated with blood from a heel stab is placed in a bacterial plate of B. subtilis in which there is a special inhibitor. If PH is present in abnormal concentration the inhibitor is neutralised and growth of B. subtilis occurs.

If the test is positive the baby must be subjected to complex tests to establish the type of PKU.


PKU IN THE MOTHER


Transmission is by a recessive gene and it has been estimated that about 1:50000 mothers have undiagnosed PKU. The following ‘at risk’ groups should be screened:


1. Mothers with a family history of PKU.


2. Mothers of low intelligence.


3. Mothers who have had infants with microcephaly (this has an association with PKU).

Screening is complicated by the wide diurnal variation in PH levels and several tests are needed.

A woman with PKU should preferably return to a low PH diet before conception or as soon as she is pregnant. Her infant will also require Guthrie test monitoring.

In the common type 1, the diet must be low-phenylalanine for life. Failure to control PKU results in mental retardation and progressive neurological deterioration.

The Guthrie blood test can also be used to exclude HYPOTHYROIDISM, by measurement of thyroxine levels or thyroid stimulating hormone, the latter being more commonly used.

In the future the blood may also be used to screen for other conditions such as cystic fibrosis.


NURSING CARE



MANAGEMENT OF THE NEWBORN BABY



When given orally to breastfed babies, further doses of oral vitamin K will be required during the first month of life. It is particularly important to give vitamin K after birth if the mother is on oral anticonvulsants.



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Usually the partner will have been present at birth and the baby is given to the mother and partner to hold as soon as the cord has been cut. If admission to the special care nursery is required, facilities should be provided to allow both parents and other family members to make frequent visits.

Ideally the baby should be offered a period of skin-to-skin contact with the mother, uninterrupted for half an hour. This greatly facilitates breastfeeding.

About 6–8 hours after delivery, traditionally, the baby is bathed and then dressed in a gown and placed in a cot in room temperature between 18 and 20°C.

The ideal cot for the newborn should be draught-proof and easily cleaned. It should be possible to raise and lower the head, and there should be a box for the toilet materials provided separately for each baby.

The importance of ‘bonding’ between the mother and child is widely recognised. Bonding is encouraged by nursing mother and child in the same room, with the cot alongside the bed so that there may be intimate contact. This facilitates demand feeding by the baby.



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PHYSIOLOGY OF THE NEWBORN




STOOLS


Meconium (mainly cast-off cells, mucus and bile pigment) is passed for the first 2–3 days. It should appear within 36 hours of birth. The bowel is sterile at birth but is colonised by bacteria within a few hours. Formed stools usually appear by the 5th day, normally light in colour and with the odour of faeces.


RESPIRATORY SYSTEM


The fetal lungs are airless and filled with lung fluid and amniotic fluid. The fetus exists at an arterial oxygen pressure of approximately 4.5–5.5 kPa. This changes quickly to adult levels with the establishment of respiration. The rate is up to 40/minute and there may be much irregularity although this usually settles to under 40 per minute 8 hours after birth.


URINE


The fetus swallows liquor and the kidneys excrete in utero. Urine should be passed within 2 hours of birth.


GENITAL SYSTEM


Manifestations of oestrogen withdrawal may occur. There is sometimes swelling of the breasts and even a little colostrum secretion (‘witches’ milk’). The female may bleed a little from the vagina and the male may develop a transient hydrocele. No treatment is required.

Jun 15, 2016 | Posted by in OBSTETRICS | Comments Off on The Newborn Baby

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