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Biomedical subjects

E N Hey

Publications and source records attributed to E N Hey.

At least 55 records · Page 3Linked to original sources
PubMed1979

Neonatal death in babies with rhesus isoimmunization.

In the 27 years, 1951--1977, 4315 babies weighing over 1 kg were born alive in Newcastle suffering from haemolytic disease of the newborn due to Rhesus isoimmunization; 197 (4.5 per cent) died within four weeks of delivery. Many babies with severe anaemia (cord Hb less than or equal to 8 g/dl) died of cerebral and/or pulmonary haemorrhage as a result of coagulation failure; others with hydrops had a chance of recovery with intensive care as long as there was no associated pulmonary hypoplasia. Hyaline membrane disease was no more common in babies with haemolytic disease than in other preterm babies of comparable birthweight, but incorrect assessment of gestational age prior to the induction of labour increased the risk of death from hyaline membrane disease. The introduction of closed chest cardiac massage virtually eliminated the risk of sudden unexpected death during exchange transfusion but there was still a 1.5 per cent chance of sudden circulatory collapse during exchange transfusion. Affected babies of less than 36 weeks gestation with respiratory problems face a substantial risk of kernicterus when the indirect serum bilirubin level exceeds 270 mumol/l (15 mg/100 ml). The establishment of a single referral centre for Rhesus isoimmunization reduced neonatal mortality in the area to half the national average in the early 1950's and this superiority was maintained throughout the next decade.

Edema↗
PubMed1978

Controlled trial of hyposensitisation to Dermatophagoides pteronyssinus in children with asthma.

Hyposensitisation with Dermatophagoides pteronyssinus tyrosine absorbate in asthmatic children with bronchial sensitivity to D. pteronyssinus was effective in a 12-month double-blind controlled clinical trial. Compared with controls, treated children used a smaller quantity of drugs while maintaining clinical and lung function improvements. In most children who improved there was no change in immediate response to D. pteronyssinus on bronchial provocation test, but the late reaction was lost in half the patients and these showed the greatest improvement in symptoms.

Adolescent↗
PubMed1976

Rapid assessment of gestational age at birth.

A simple scoring system based on skin colour, skin texture, breast development, and ear firmness that can be performed even in an ill baby without manipulation or movement enables gestational age to be estimated to within +/- 15 days (95% confidence limits) at any time in the first 2 days of life. More complex techniques only marginally improve this estimate.

Birth Weight↗
PubMed1970

The range of thermal insulaton in the tissues of the new-born baby.

1. Rectal temperature and skin temperatures were measured in twenty-eight naked babies weighing 1.1-4.5 kg, lying supine in environments of 25-31 degrees C when air speed was 4-7 cm/sec. The ratio of external insulation to internal or tissue insulation for the whole body averaged 2.7 but varied inversely with body weight; the ratio was higher than this on the trunk, and five times lower than this on the hand and foot. The mean ratio rose threefold when environmental temperature was increased to 34-35 degrees C.2. Direct measurements of heat flow from the back of a hand placed in a water jacket maintained at 32 degrees C were made in thirty-three babies. Heat loss averaged 3 kcal/m(2).hr. degrees C at low environmental temperature, but the loss was often rather less than this in the first 24 hr of life. Heat loss from the hand increased three- to fourfold, during exposure to an environment of 35 degrees C.3. When babies more than 48 hr old were exposed to an environment of 34-35 degrees C, heat loss from the hand only increased when rectal temperature reached between 36.6 and 37.3 degrees C; a slightly higher rectal temperature was usually reached before heat loss rose in babies less than 24 hr old.4. Similar methods were used to study specific tissue insulation in three babies with congenital defects of the brain who lacked evidence of temperature control. No changes in insulation were detected in these three babies following changes in environmental temperature.5. It is concluded that the range and pattern of control that can be exerted over the specific thermal insulation of the tissues is essentially the same in babies 2-20 days old as it is in adult life.

Anencephaly↗
PubMed1970

The total thermal insulation of the new-born baby.

1. One hundred and seventeen healthy new-born babies weighing between 0.9 and 4.8 kg at delivery have been studied during the first ten days of life, and sixteen of these babies have been studied serially for 6 weeks after birth. The babies lay supine in a draught-free environment (air speed 4-5 cm/sec) of moderate humidity. The operative temperature was between 26 and 38 degrees C for the babies who were studied naked.2. Total non-evaporative heat loss was calculated from simultaneous measurements of oxygen consumption, evaporative water loss and the concomitant change in mean body temperature.3. Approximately 10% of the total body surface area was in contact with the mattress or floor. Conductive heat loss accounted for only about 5% of all non-evaporative heat loss when the naked baby was lying on a thick foam mattress, but for as much as 25% when the baby was lying in a water-jacketed chamber with a floor of clear plastic approximately 5 mm thick.4. Insulation to heat loss by convection and radiation varied with environmental temperature. Total specific insulation was low in a warm environment when the naked baby vasodilated, and rose by between 16 and 25% to a maximum in an environment of 31 degrees C. It decreased significantly when the baby became physically active in environments with a temperature less than this.5. Total specific insulation in an environment of 31 degrees C varied with body size: it averaged 0.156 degrees C.m(2).hr/kcal in seven naked babies weighing 0.9-1.2 kg, rose to 0.190 degrees C.m(2).hr/kcal in twelve babies weighing 1.8-2.2 kg, and averaged 0.201 degrees C.m(2).hr/kcal in the thirty-four babies who weighed over 3 kg. Tissue insulation accounted for 23% of this total specific insulation in the smaller babies, and about 28% of the total in babies weighing over 3 kg.6. Clothing ten babies in a vest, napkin and long cotton nightdress increased the total specific insulation by an average of 0.23 degrees C.m(2).hr/kcal.

Birth Weight↗
PubMed1969

The relation between environmental temperature and oxygen consumption in the new-born baby.

1. Oxygen consumption (V(O2)) has been measured serially in sixty-eight infants during the first 10-35 days of life, when naked in a Perspex metabolic chamber, by recording the changes in circulating gas volume. Air speed in the chamber was 4-5 cm/sec, and absolute humidity approximately 18 mm Hg.2. When environmental temperature (T(E)) was 35-38 degrees C minimal V(O2) rose from 5 to 7 ml.O(2)/kg.min during the first 2 days of life in infants weighing over 2.5 kg, and more slowly in the first 7-10 days in infants under 2 kg at birth.3. Physical activity and V(O2) both increased when T(E) fell below 33 degrees C: the increase appeared to be linearly and inversely related to T(E), but the rise in heat production was seldom enough to prevent a fall in rectal temperature. In infants over 2.5 kg at birth the mean increase amounted to 0.56 ml.O(2)/kg.min for each 1 degrees C fall in T(E) when 4-12 hours old, and 1.27 ml.O(2)/kg.min when between 4 and 20 days old. In infants weighing 1-2 kg at birth the mean increase was similar in the first 12 hr, but the coefficient rose more gradually with age.4. The maximum V(O2) in infants over 2.5 kg at birth and over 2 days old was about 2(1/2) times the minimum V(O2); the maximum was rather lower in most infants of low birth weight.5. In seven infants who were motionless and apparently asleep after sedation with chloral hydrate, the increase in V(O2) at low T(E) was reduced but still significant.6. It is concluded that the new-born baby responds to a cool environment with a considerable immediate increase in heat production; visible muscular activity appears to account for only part of this increase.

Age Factors↗
PubMed1969

Evaporative water loss in the new-born baby.

1. Measurements of total evaporative water loss (EWL) were made on sixty-three premature and full-term babies 0-65 days after birth within a closed Perspex chamber under varied environmental conditions by measuring the flow and absolute humidity of air entering and leaving the chamber. Control experiments suggested that the method underestimated loss by about 5%. Measurements of O(2) consumption were made concurrently by recording the volume change of the closed gas circuit.2. The total basal EWL averaged 10.8 g H(2)O/m(2).hr in infants 2-10 days old when ambient water vapour pressure (P(H2O)) was 18 mm Hg; basal EWL was correlated with basal metabolic rate at all ages studied and evaporative heat loss accounted for approximately 23% of basal heat production.3. Respiratory water loss was measured by detecting the water added to air at 33 degrees C passed across the face of eight infants in a trunk plethysmograph. Respiratory water loss was inversely related to the water vapour content of the inspired air; gas appeared to leave the nose approximately 95% sat. at 35.6 degrees C.4. Measurements of total EWL were obtained when humidity was varied and skin loss was calculated by subtracting estimated respiratory loss from total loss; changing P(H2O) from 7 to 25 mm Hg appeared to decrease basal skin water loss by only 1.5 g/m(2).hr.5. No consistent changes in EWL were obtained when environmental temperature (T(E)) was varied between 28 and 34 degrees C. Active sweating occurred in infants 0-10 days old born within 3 weeks of term when T(E) exceeded 34-35 degrees C and rectal temperature (T(R)) rose above 37.2 degrees C. The threshold rectal temperature at which sweating was detected fell significantly in the first 10 days of life; EWL increased two to fourfold when T(R) rose to between 37.5 and 37.8 degrees C.6. In infants of less than 215 days post-conceptual age (term approximately 268 days) EWL increased less than 50% at T(R) 37.7-37.8 degrees C; it is concluded that the sweating mechanism is defective in these infants.

Basal Metabolism↗
PubMed1969

The response of the sweat glands of the newborn baby to thermal stimuli and to intradermal acetylcholine.

1. Measurements of evaporative sweat loss were made on fifty-six premature and full-term babies 1-67 days after birth with an infra-red analyser and a ventilated capsule placed on the thigh. Measurements were also made of total evaporative water loss while in a closed metabolic chamber and of the regional distribution of sweating with starch-iodine paper.2. No sweating to thermal stimuli could be detected in infants of less than 210 days post-conceptual age, even when rectal temperature rose as high as 37.8 degrees C. In older infants sweat was detected first on the forehead and temple, later on the chest, and usually by 240-260 days post-conceptual age on the legs (term approximately 268 days). Generalized sweating on the limbs appeared at an earlier post-conceptual age in the more prematurely born infants.3. The response of sweat glands on the thigh to an intradermal injection of 2 mug acetylcholine (ACh) was tested. No sweat response was detected in infants under 225 days post-conceptual age, while all infants born within 2 weeks of term responded. The response was often augmented after 2-5 tests at 5-10 min intervals; all the eight infants born within 2 weeks of term who were examined twice in the first 2 weeks of life showed a greater response on the second occasion.4. An average of 414 active sweat glands/cm(2) were detected on the thigh in eight babies 7-10 days old born within 2 weeks of term. This was 6(1/2) times the number found in adults. The mean peak sweat rate to chemical stimulation was however only 2.4 nl./gland.min, which was 3 times lower than the maximum rate recorded in adults.5. In five infants with congenital defects of the brain and complete absence of temperature control there was no sweat response to thermal or direct chemical stimulation of the glands.6. Functional maturation appears to depend on intact central innervation and is marginally hastened by post-natal factors. Immaturity of the sweat glands can account for the lack of any response to thermal stimuli in premature babies, but not for the modest thermal response obtained in babies at term.

Acetylcholine↗