Temperature control guide
Introduction
The child and the adult can easily control the body temperature according to the
thermal environment.
In opposition to the above mentioned, the newborn, especially the immature one, the
one with neurological sequels, the sick one especially, can not adapt to temperature
change and frequently will present hypo or hyper temperature.
Numerous studies show that body temperature changes (hypo or hyper temperature)
are either the result of the environment; either is secondary to the newborn disease
(Buczow and Klein, 1969; Stanley and Alberman, 1978; Glass, 1975). Even immature
there is no reason to believe that the newborn is not feeling uncomfortable when he
has high or low temperature.
The body temperature changes are in this context an important factor in newborn
survival and in his future normal development, being produced by the disease or
producing themselves the disease.
The current chapter has the following objectives:
Objectives
This guide must become familiar to the physicians and nurses in any maternity
hospital regardless its degree and by the ambulance physicians and nurses that
assist births or transport newborns, by parents and family physicians that care for a
child at home.
The group of newborns to which it will be applied will be identified (sick newborn,
premature newborn, newborns at home etc.)
The risk of hypo or hyper temperature will be identified, looking for its cause in order
to decrease as much as possible its effects and in order to see which treatment
protocol is required.
The consequences degree will increase with the severity of the modification and with
the decrease of VG. This is why these newborns with troubles should be cared for in
tertiary centers and they should be transferred in these centers when needed.
The temperature control protocol is one of the easiest protocols to be applied, but it
has a major impact over the newborns morbidity and mortality. This is why it can be
easily applied; it is safe, but compulsory.
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Knowing the temperature neutrality zone and maintaining the newborn as close as
possible to this zone.
Temperature measuring technique
Application protocol
Identification of cases with hypo or hyper temperature and treating them
I. Physiological considerations
Definitions
Body temperature and temperature neutrality
A. Definitions
Thermal regulation = Phenomena and factors that regulates the equilibrium between
the productions and lost of heat; adaptive mechanism to the extra-uterine life
(nutrition, adapter, respiration).
Thermal genesis – production of heat.
Thermal lisis – heat loss.
Thermal equilibrium – equality between the production and loss of heat; there is no
stored or lost heat.
Thermal or neutral environment – set of thermal conditions (environment t°, air draft,
relative humidity, temperature of the surrounding objects) in which the body
temperature is maintained by minimal heat production at rest. There are no important
physical loses.
Homeotherm – organism that maintains its temperature under strict limits through
physiologic adjustments. In a cold environment it responds to the heat loss by
producing heat (increases the metabolism).
Poichilotherm – organism that responds to heat loss by proportionately decreasing its
metabolism (preterm newborn < 29 weeks in cold environment acts as a
poichilotherm).
B. Body Temperature and thermal neutrality
Heat production
Heat production by the body is a mechanism that is realized through a metabolic
process in which the organism has to equal the heat that is loss through surfaces by
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the newborn’s body and the cold air that enters the lung in a period of time when the
average body temperature remains controlled.
A characteristic of the homoeothermic organisms is the possibility to maintain their
temperature in restricted limits through physiologic adjustments. This characteristic
allows the human body to produce excess heat in case of a cold environment.
In adult the heat production is realized through: volunteer muscular activity, involunteer muscular activity (rhythmic, trembling) and metabolic heat production
realized through glicolysis, lipolysis and oxygen consumption.
In adult heat production through trembling or frison is quantitatively the most
important un-volunteer mechanism of heat production regulation. In newborn the first
rank is occupied by heat production secondary to trembling.
Studies on humans and animals showed that heat production by lipolysis of the
brown fat contributes in the biggest degree to metabolic heat production.
Metabolic heat production in newborn is realized through:
a). Lipolysis of the brown fat
The brown fat represents in newborn about 2-6% of the body weight and is located
the nape of the neck, between the scapulae, and around the kidneys and adrenals.
The brown fat is different both metabolic and morphologic from the white fat that is
much more abundant. The brown fat cytoplasm is rich in mitochondria and contains
numerous fat vacuoles (comparative with only one vacuole in the white fat).
In case of skin temperature decrease the local norepinephrin that produces an
increase of the triglicerides lipolysis that will produce un-saturated fatty acids and
glycerol with a high oxygen and glucose consumption (30% oxidates).
The glucose consumption is assured by glicolysis and neo-glucose-genesis. After
glycolysis the glycogen is transformed in the liver in glucose, resulting in secondary
hypoglycemia and reserves exhaustion.
The high oxygen consumption is provided by circulation redistribution and
hyperventilation.
b). The use of exogenous energy substances – nutritive substances or aliments
in newborn these are used initially to assure the basal metabolism and the normal
body temperature. These reserves are low.
In general heat production in preterm newborns is limited due to the fact that the
brow fat is insufficient (10g at the ones under 1000g and under 28 gestational
3
weeks), oxygen duty (newborns with birth asphyxia or age specific respiratory
diseases), low glycogen reserves, insufficient production of norepinefrin, low nutritive
substances intake in the first 2 weeks of life.
Conclusions
The newborn responds to cold by activating its metabolism (attention: face cold by air
flow activates the metabolism before lowering of the central temperature).
The heat producing capacity is good at in term newborns, but lower than in the adult
(the temperature control zone is up to 0°C in adult and up to 20-23°C in newborn).
The heat production capacity is lower in premature newborns compared with in term
newborn.
Practically the production being low, the loss has to be limited.
C. Heat loss
The heat loss can be classified in 3 types:
-
from the interior of the body towards the body surface (intern gradient =GTI)
-
transfer of heat from the surface of the skin to the environment =GTE
4
-
loss of heat through the respiratory tract in case of mechanic ventilation with
cold air
GTI
These heat losses are realized under the influence of the physiological mechanisms
that regulates the skin blood flow. These physiological control mechanisms of the
newborn may be adulterated by the intern gradient (vasomotor), the skin blood flow
changes.
The heat loss through GTI is favored in newborn by:
-
high body surface compared to the body weight (S/G>)
-
Thin skin fat, practically inexistent in the ones with the GA less than 28 weeks
and weight under 1000g.
-
the epiderma is thin with flat cells and with an increased blood flow with
numerous vessels
GTE
The heat transfer from the surface of the body to the environment is realized through
4 mechanisms: conduction, convection, radiation and evaporation.
The heat transfer is complex and the contribution of each mechanism may be
different.
a) Heat loss through convection
This is realized by replacing the warm air around the newborn with cold air. It
depends on the temperature difference between the two. If the environment
temperature is higher than the body surface temperature then the heat will increase
through convection.
The heat loss through convection depends on the air speed. If the speed is high, the
heat loss increase. The convection is the major cause of heat loss when the newborn
is exposed in a cold room with draft.
b) Radiation represents a heat loss through transfer to cold surfaces at a distance
(walls, windows, incubator’s walls).
It is proportional with the difference between this surface temperature and the body
surface temperature, but independent of the mixed air temperature.
It is an important way of loosing heat when the newborn is exposed undressed in the
delivery room.
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c) Evaporation is a heat loss realized through water evaporation on the body surface
and respiratory mucous membrane. Each evaporated water mol consumes 560 heat
calories.
Normally, through evaporation is lost a quarter of the at rest production of heat (Hey
& Katz).
Approximate ¼ of this loss is realized through water evaporation at the respiratory
level, the rest through passive diffusion of the water through skin.
The heat loss through evaporation is not important in the in term newborn, with the
exception of the birth moment when the skin is wet with amniotic liquid. In case of
excessive heat, the mature child is able to increase the heat loss through evaporation
as a response to environment temperature increase through perspiration.
The preterm newborn has a higher loss of heat through evaporation. It increases with
the degree of prematurity, being higher in the early neonatal period.
This high evaporation rate is secondary to the immaturity of the newborn skin that is
thin, with a cornos layer weakly keratinized, with low resistance to water diffusion.
At about 2 weeks of life an epidermal barrier is developed, that can be compared with
the one of an in term newborn, it limits the heat losses.
The skin water loss increases in the presence of tegument lesions due to monitoring
in preterm newborns.
The heat loss through evaporation increases when the newborn is exposed to radiant
heat.
Using the radiant heat increases the heat loss through evaporation with a factor of
0,5-2,0°C.
This increase might be explained partially by the increased surface temperature,
increase air movements and low local humidity when the newborn is exposed to
radiant energy.
The heat loss through evaporation is increased in newborn less than 30 weeks of
gestation age, in the first week of life so that their treatment is quite difficult.
Reducing the losses through evaporation is required and it can be realized through:
-
Increase humidity – situation when the heat loss decreases linearly (fig. 10-3).
At a very high humidity the heat loss is very low.
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-
Air draft protection, reason why the newborns with extremely low weight will be
placed in special incubators with double walls and maneuvered only through
the incubator’s doors.
-
Covering the skin with impermeable sheets realized from fine plastic sheets,
blankets etc. reducing in this way the water loss by 75%. Oiling the skin with
paraffin reduces the heat loss with 50%.
d) Conduction: heat loss through direct contact with a cold surface (table, cold
clothes, scale).
The phenomena can be extremely unpleasant for the newborn that at birth is wet of
amniotic liquid and placed on a cold table. The thermal shock can be avoided by
placing the newborn on a therapy table with radiant warming, wiping the wet skin and
replacing the wet cloths, placing a cover on the head.
GTE is minimal in a neutral thermal environment and the heat loss is minimal at a
humidity of 100%. The physical loses are favored in newborn by a high skin surface
exposed to cool (uncovered head, deflected hypotonic, big uncovered head), thin
skin with high permeability.
In conclusion
GTE is influenced by:
-
environment factors: environment temperature, relative humidity, air flows
-
type of child: exposed skin surface (naked, wet, big head, thin skin, damaged
skin)
D. Environment temperature’s influence over body temperature
(Figure A)
The effect of environment temperature over the oxygen consumption in case of
respiration in normal air (O2 20%) and in hypoxia (O2 12%) – experimental study:
If the organism breath normal air (O2 20%) and the environment temperature is of
neutral temperature the oxygen consumption is minim and the rectal temperature is
constant at 37°C;
If the animal is cold
breath normal air (O2 20%) the oxygen consumption increases a lot and the body
temperature is constant
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breath air with little O2 (O2 12%) the oxygen consumption do not increases and the
rectal temperature decrease.
Conclusions
The cold and un-hypoxic child tries to maintain the body temperature by increasing
the oxygen and calories consumption in order to produce additional heat (acts as a
homoeothermic).
The cold child that is warmed up must receive oxygen supplementary.
The newborn homoeothermic mechanism may be abolished through numerous
interventions, this is why it is better to be protected thermal.
(Fig. B) If the environment temperature decreases under the critical point A – the
oxygen consumption increases – the body temperature is maintained if the heat
production is adequate.
If the cold continues – the body temperature decreases – under point B; the
temperature regulation center is paralyzed by cold – the oxygen consumption
decreases 2-3 folds for each decrease with 3°C of the body temperature.
If the environment temperature increases over the neutral point hyperthermia is
installed.
Conclusions
The oxygen consumption and the heat production are minim in two areas: the severe
cold zone and in the thermal neutrality zone.
The physician must keep the child in a safe thermal environment (the thermal
neutrality zone) or in a thermal comfort zone that will be different according to GN,
VG, and age of the preterm newborn.
From the clinical point of view it is important to note that the newborn may not be in a
thermal neutrality zone, but the rectal temperature may be normal.
The first mechanism to save heat is vasoconstriction, and the phenomenon may be
easily seen by measuring the body temperature in a periphery area of the body.
The most selective method to establish the vasoconstriction is to measure
comparatively the rectal temperature and the foot temperature ( ).
Hyperthermia is onset much quicker in newborn than in adult.
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The newborn has a low capacity of loosing heat because his high temperature is in
direct relation with the one of the environment and he has a high ratio
surface/volume.
In order to maintain the body temperature constant, the child thermal regulation
system maintains the balance between the heat production, the blood flow at the skin
level, transpiration and respiration.
The thermal regulation systems are more limited in newborns due to lack of
insulation. For the naked adult the inferior limit for temperature control in 0°C (32F),
while for the in term newborn it is 20°C (68°F – 73,4°F).
It is required here to note that the insufficient stability of the body temperature in the
small pre term newborn does not indicate an immaturity of thermal regulation if the
system is intact.
According to Bruck, the system insufficient stability is due to the discrepancy between
the effective system efficiency and the dimensions of the body.
In uterus
While the baby is inside the mother’s uterus, the heat production is dissipated
through placenta to the mother.
Normally, the fetus temperature is higher than the mother’s. This system is ideal for
the fetus, excepting the period when the mother has hyperthermia.
During the fetal period of the pregnancy, the fetus’s temperature will increase more
than the mother’s temperature.
After birth
After birth the body temperature decreases quickly, mainly due to evaporation from
the wet amniotic liquid skin.
The low under-skin tissue of the newborn, the high ratio surface/mass compared with
the adult together with the cold air and walls of the delivery room increase the
newborn heat losses by 2-3°C.
The passage from a moderate cold to a severe one may cause metabolic acidosis,
low arterial oxygen level and hypoglycemia. A moderate coldness may be beneficial
to its adaptation to extra-uterine life. Cooling the skin receptors may play a
significantly role in breathing initiation and in stimulating the thyroid functions.
The vasoconstriction and periphery resistance observed in case of moderate cooling
alliterates the systemic vascular resistance, reducing the right-left shunt from the
level of the arterial duct.
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In case of a severe cooling severe hypoxemia may result and even death. (Fig. B)
The effect of the environment temperature over the oxygen consumption and body
temperature:
If the environmental temperature decreases under the critic point A → the O2
consumption increases → the body temperature is maintained if the heat production
is adequate
If the cooling continues → the body temperature decreases → under point B the
temperature regulation center is paralyzed by cold – the oxygen consumption
decreases 2-3 folds for each decrease with 3°C of the body temperature.
If environmental temperature increases over the neutral thermal zone the
hyperthermia appears.
The oxygen consumption and the heat production are minim in tow zones: the severe
cold zone and the thermal ventilation zone.
In conclusion (according to Hey and Katz):
The rectal temperature is not a good indicator that the newborn is in a neutral thermal
zone
The rectal temperature decreases only when the maxim efforts of the newborn to
maintain its central temperature were overcame.
The skin temperature is a better indicator for environmental temperature, because in
cool it does not decrease the first (through vasoconstriction).
The organism’s response to cooling
Light cooling (benefic) produces:
stimulates respiration and thyroid glade
vasoconstriction → increase arterial pressure → short decrease through the arterial
duct
Excessive cooling → grave effect:
hypoxia
acidosis.
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The vicious circle resulted after excessive cooling of newborn
E. Nutrition and temperature
As a result of the relation between the metabolic ratio and the body temperature,
both the liquids needed and the nutritive requirements in order to increase … directly
connected with the temperature regulation mode.
The fact is extremely important for the small pre term newborn that has difficulties in
maintaining his temperature; his caloric intake is limited by a low adaptation capacity.
He needs a high thermal environment in order to use the received calories to
increase his weight.
A high metabolic ratio leads to high loss of liquids.
In case the newborn has a low food requirement, being in a thermal neutral point, his
caloric requirement for gaining weight is low.
Insensible water losses are in concordance with the metabolic ratio, but 25% of the
total heat produced disappears in this way.
An increased metabolic ratio leads to high water loss and secondary to a high liquid
requirement.
A point of thermal neutrality allows for a low alimentary intake a decrease of the
caloric requirements useful for gaining weight.
Glass and collaborators were able to compare the effects of a control temperature
over growth, by comparing two categories of newborns weighting between 1-2 kg and
having one week of gestational age.
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These newborns were divided in 2 groups: the “warm” group (abdominal skin
temperature of 36,5°C) and „standard” group (skin temperature maintained at 35°C).
Both groups received 120 Kcal/kg/day.
The “warm” group presented a weight and height gain significantly higher than the
“standard” group. A significantly weight and height gain was obtained in the second
group only after increasing the caloric intake maintaining the same skin temperature.
F. Central regulation of temperature
The integration of the thermal receptors messages will be done in hypothalamus
under very diverse environment conditions.
The skin temperature may vary between 8 and 10°C, and the hypothalamus’ with +
0,5°C.
Diverse temperature variations may exist, variations produced in general by the
simpatic system in case of asphyxia, hypoxemia and other disorders of the central
nervous system. The newborn has usually a body temperature of about 37.5°C, while
the pre term newborn’s is 36,5°C. Because important thermal regulation processes
take place at small deviations of 0,5°C, any variation, even a minim one may be
extremely important.
II. Normal body temperature and it’s measuring
•
Rectal temperature
- Normal values: 35,5 – 37,5°C
- Measured using a mercury thermometer introduces in the rectum in
a 30° angle
- 3 cm for the in term newborn
- 2 cm for the pre term newborn
- duration: 1 minute
- it is not used in EUN.
Rectal temperature decreases only when all the efforts to maintain the central
temperature were overcame by the newborn.
Disadvantages
-
-
danger of rectum and colon perforation; the newborn colon is
changing the angle at 3 cm. this is why introducing the thermometer
over 3 cm has the risk of perforating the colon. Rectum perforation is
a disease with very high mortality.
The risk of broking the thermometer
Stimulates supplementary defecation with loss of liquids and
calories.
Rectal thermometer is not sterile, it bears high risk of transfer of
some digestive diseases
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-
- The procedure is uncomfortable
The procedure in newborn may produce a vagal stimulation resulting in
cardiac rhythm disorders and bradycardia.
• Temperature in axilla
- Measured in axilla for 3 minutes
- Normal value: 35,6 – 37,3°C
Advantages:
-
simple and safe
easy access
low risk for infections
Disadvantages:
can not be applied when the newborn is in shock with periphery
vasoconstriction
abdominal skin temperature
•
Normal value:
-
NB in term: 35,5 – 36,5°C
NB pre term: 36,2 – 37,2°C
Measured with a skin sensor at the level of the abdomen (avoiding the liver
and bones). The electrode will be glued with an adhesive
•
Temperature on the foot
Normal value: 34,5 - 35°C.
III. APPLICATION PROTOCOL
•
Birth room
At birth, the newborn’s body temperature is 1°C bigger than the mother’s and can
easily decrease under the normal values if a protocol for temperature maintenance is
not respected.
The temperature in the birth room must be over 25°C.
The in term newborn will be taken over in warm sheets, will be wiped and the wet
sheet will be discarded. The newborn will be placed skin on skin to his mother, in this
way he will keep a temperature similar to the one of a newborn exposed to a radiant
warming source.
The pre term newborn will be putted under a radiant warmer after birth. The very
small pre term will not be washed because they are not stable cardio-respiratory after
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birth. (37.1. The “kangaroo” position skin to skin of the newborn was demonstrated to
be a good method to maintain the temperature.)
The first bath will be delayed till thermal stabilization.
In case of resuscitation it will be done compulsory under a radiant warmer or
supplementary heating under a heat source of 400 W placed at 60 cm from the
newborn.
•
•
Transport in the ward
- Warm incubator with own batteries and independent oxygen source
or in thermal security conditions according to the level of the
hospital.
Care in the ward
In term newborn
The bath will be done when the newborn is stable thermal and homodynamic
and cardio-respirator equilibrated. The health newborn will be washed immediately.
The sick newborn will wait till the above conditions are attained. The newborn is
dressed and covered with a wool or cotton blanket. Attention! The head must be
covered!
The temperature in the ward must be over 24°C, relative humidity 40-60%, or
else supplementary warming sources will be used.
The pre term newborn 2.500 – 2.000 grams
-
Room temperature: > 25°C.
dressed, covered with a wool or cotton blanket, double cap on the
head
Cared for, in warmed bed or incubator.
The pre term newborn under 2.000 grams:
-
-
Room temperature >25°C, dressed, covered with a wool or cotton
blanket, double cap on the head
Incubator with simple walls, in warmed room (20-22°C) far from cool
surfaces (doors, windows). If in the room is not enough warm, the
newborn will be placed dressed in the incubator or covered in a
insulating sheet. The incubator temperature is according to VG, GN
and post birth age.
incubator with servo-control
ƒ closed incubator with servo-control: temperature in incubator
is regulated according to the newborn constant temperature,
weight, VG and post birth age (conform to the tables)
ƒ open incubator with servo-control: the newborn will be placed
under a warming source activated through a servo-control
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method placed on the abdomen skin in order to maintain a
skin temperature of 36,2 – 36,8°C.
Maintaining a newborn temperature in a thermal neutrality zone minimizes the
heat production, the oxygen consumption and the nutritional requirements for weight
gain.
The standard temperature maintenance methods are difficult to obtain, this is
why are always new warming methods developed. A new method is to keep the
newborn naked in an incubator, while a system of warm air flow warms the incubator
walls.
This method is extremely expensive and was developed by Hey, who uses a
double walls incubator, the interior wall being the one warmed up.
The last generations of incubators have incorporated other principles and are
build with double walls, their warming being controlled by a small computer that
allows optimal accommodation even for the most fragile newborns.
Monitor the temperature
Continuous
•
•
•
•
•
pre term newborn under 1.500 grams
in term newborn with central temperature under 34°C, till normalization
severe asphyxia at birth
septic shock
meningo cerebral hemorrhage
Discontinuous
•
•
•
•
•
each hour till the stabilization of the central temperature in the first 24
hours
every 4 hours, from day 2-3
every 4 ore, from day 4-7
after day 8, every 12 hours
weight 2 times a day.
IV. Newborn HYPO AND HYPERTHERMIA
A. Hypothermia
a. Definition – decrease body temperature under 36°C (rectal
temperature)
b. Cause
At birth – it will be anticipated particularly to the low weight newborn and/or to
the one that required resuscitation.
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It is due to:
•
•
•
•
•
•
Cool room
Air flow
Cool sheets, scale
Resuscitation kit not warmed
Cold oxygen on the newborn face
Newborn kept in a cool place, resuscitated without a warming
source
In the newborns ward
•
•
•
Bath before thermal stabilization
Room temperature under 22°C
Naked newborn manipulated in incubator, in a ward that is not
warmed
• Cool draft
• Defect open or closed incubator
• Alteration of the temperature regulation mechanisms (central
nervous system malformations, meningo cerebral hemorrhage,
severe infections etc.)
c. Clinic signs of hypothermia in newborns
Tegument and mucosa – the skin is usually red and cold. Mann and Eliott
described an „aura” of cooling from the truncheon to the peripheries.
Body temperature decreases under 32,2°C. The most evident clinical sign is
the red tegument (frequently believing that the newborn „looks very good”).
The red color is due to the insufficient dissociation of oxihemoglobin at low
temperature.
It can be associated with central cyanosis or paleness or sclerem of face and
limbs.
Respiration
•
•
bradypneic, unregulated, superficial, associate cu expiratory moan
recidivate apnea, especially in the pre term newborn with low weight
at birth
Cord – bradycardie direct proportional with temperature decrease
Abdomen –abdominal distension, throw up
Kidney – low urine volume of pre renal cause
Behavior change
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•
•
•
•
•
alimentation refusal
weak crying „pathetic”
lethargic with low response to pain
trembling is rarely observed in newborns
CNS depression constantly appears, in case of hypothermia and
will produce low response to pain; the pain stimulus (for instance,
injections) will produce a minimal reaction, maybe a weak cry.
Metabolic problems
•
•
•
•
•
•
hypoglycemia
metabolic acidosis
hyper natremia
increased urea and nitrogen
changes in blood coagulation that leads to hemorrhagic
generalized disease or frequently pulmonary hemorrhage, this
being the main death cause.
The source of hypothermia must be found.
d. Treatment
A lent warm up of the newborn is recommended. The newborn will be
preferably placed in a closed or open incubator with servo control. The incubator’s
temperature in this case will be set with up to approximate 1,5°C higher than the
abdominal skin temperature of the newborn.
The abdominal skin temperature must reach an interval between 36,5 and
37°C (97,7-98,6°F).
Baumgart, in 1999 (fig. 33-4 Avery – The temperature variations for 10 pre
term sick newborns with an average weight of 1,39kg, cared in a open incubator with
servo control.
Because the room temperature is 10°C, this makes the cold air to enter the
incubator, which leads to a heat loss double compared with the heat production
through metabolism. The evaporation helps the physic heat loss.
Usually, the newborn organism produces only one third of the energy needed
in order to maintain the body temperature.
In case of a very small pre term child, the open incubator must increase
through servo control very much the warming capacity, producing consequently high
water loss through evaporation. The radiant loss is diminished by the double warmed
walls, if a closed incubator is used or by padding the wall of the open incubator with
aluminum foil that reflects the heat.
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In order to reduce the evaporation and convective turbulence it is proposed to
cover the newborn (placed on the warming table) with a thin transparent plastic foil
that will be used as a blanket. This foil may cause in some situations the lost of the
contact with the servo control and this is why a very rigorous monitoring of these
cases is required.
In case of absence of an incubator the newborns with low temperature will be
warmed up in warm beds or with supplementary warming sources.
It was observed that when the difference of temperature between the body
and the environment is of 1,5°C, the oxygen consumption is minim even if the rectal
temperature might be normal.
This part of the transitional treatment model was discussed by Tafare and
Gentz (
). They did not found benefic effects when comparing lent warming up
with lent one in 30 newborns hat suffered of thermal stress.
The skin temperature, in care of warming up, will be checked every 15 minutes
till normalization, setting the warming source in concordance with the body
temperature (> 1,5°C abdominal temperature).
To take into consideration:
•
Filing in the vascular system with physiologic ser 9‰ at room
temperature in quantity of 10-20 ml/kg.b. Using the saline bolus
(20 ml/kg.b.) early in the warming up period reduced significantly
the mortality, this being more important than slow or rapid warm
up (Tafare and Gentz)
• metabolic acidosis correction with sodium bicarbonate according
to AGS supplementary oxygen will be given in case of low PaO2
(warm and humid)
• monitoring glycemia
• alimentation strict intravenous or by gavaj till the body
temperature is over 35°C. in case of a hypothermic newborn the
oral alimentation will not be permitted
• antibiotics will be indicated only in case of infection signs.
B. Hyperthermia
a. Definition: body temperature increase over normal values (rectal >
37,8°C)
b. Cause:
• excessive over heating due to:
ƒ excessive dressing
ƒ warm air
ƒ deregulate of the incubator, warmer, warm bed,
phototherapy lamp
• local or systemic infection
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•
•
deshidratation
central temperature control mechanisms alteration associated
with disease as severe neonatal asphyxia or malformations
(hidranencefalie, holoprosencefalie, encefalocel and trizomia
13), drugs
• hipermetabolism.
c. Organism’s response to overheating
• vasodilatation
• tachycardia
• hyperpnoea
• increase of the body surface by deflectation
• transpiration (when environmental temperature is over 36°C).
The transpiration limits in newborn (Matsaniotis, Cross and colab., 1871)
In newborns with VG under 30 weeks the soporific gland are in a small
number. They have a centrifuge ontogenetic development (forehead → arms →
hands → tights → legs → abdomen).
This category of newborns have a high degree of transpiration that will
decrease with post natal age.
The low transpiration capacity of pre term child increase with the gestation age
and post natal age. The pre term child transpire a little, but has high liquid loss
through evaporation.
d. Clinic signs in hyperthermia through overheating
Hyperthermia
•
•
•
•
•
•
red and hot tegument (especially at the level of the trunk and
extremities), they might confuse the medical staff, inducing a false
aspect of “good looking child”
fever, agitation, moan, irritability + apnea (Perlstein, Belgaumkar)
diarrhea, CID, hepatic and renal insufficiency (Bacon)
convulsions → lethargy → coma
death by thermal shock, with severe metabolic changes, pulmonary
hemorrhage or generalized hemorrhagic disease
sudden death by hyperthermia (Stanton, 1980).
Clinic signs of septic fever
•
•
•
•
pale skin
pale- cyanotic and cold extremities
central temperature higher than skin temperature
foot skin temperature 3 grads lower than the abdominal skin
temperature.
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Differences between the newborn with hyperthermia by overheating and the
one with septic fever
overheating
septic fever
Rectal temperature
↑
↑
Hand and legs
Warm
Cold
Difference between the abdomen
and hand temperature
<2°C
<3°C
Skin color
red
Pale with cyanotic
extremities
Other signs
Transpiration, low
turgor
Lethargy, bad
general status
Treatment
•
•
•
•
•
slow decrease of the temperature
when the cause is external (environment), the heat source will be
removed:
- phototherapy lamp
- overheated incubator
- defect servo control
- excess dressing
the newborn will be hydrated, per os or intravenous by case
protective anticonvulsive treatment will be given
if infectious fever, the following will be done:
- cultures will be done
- treatment with antibiotics will start.
ATENŢIE SPECIALĂ!
Asphyxia
In case of a sever asphyxiate and hypoxic newborn temperature control
problem arises.
When resuscitating this newborns the following should be taken into account:
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-
evaporation is reduced by immediate wiping
immediate dressing (attention – the head!), warm sheets
placing the child under a warming radiant source
no air draft in the room
the oxygen will be warmed up.
-
the immersion of a newborn in water equal with mother’s
temperature may lead sometimes to respiratory arrest. Rapid
warm up is associated with apnea episodes.
In case of apnea, in pre term with birth low weight, reducing with
1°C of the servo control temperature leads to apnea episodes.
For a newborn with apnea, the temperature will be maintained as
close as possible to the neutral point and the temperature
fluctuations will be reduced to a minim.
Apnea
-
Weight at birth and temperature
Age
1000-1200 g
1200-1500 g
1501-2500 g
+ 0,5°C
+ 0,5°C
+ 1,0°C
> 2500gr / > 36
weeks
+ 1,5°C
0-12h
35
34
33,3
32,8
12-24h
34,5
33,8
32,8
32,4
24-96h
34,5
33,5
32,3
32
Age
< 1500 g
1501-2500 g
> 2500 g / > 36
weeks
5-14 days
33,5
32,1
32
2-3 weeks
33,1
31,7
30
3-4 weeks
32
30,9
4-5 weeks
31,4
30,4
5-6 weeks
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REGLAREA TEMPERATURII UNUI INCUBATOR
Weight at birth
Day
< 1.500 g
1.500-2.000 g
> 36 weeks > 2.500 g
1
34,3 + 0,4°C
33,4 + 0,6°C
33,0 + 1,0°C
2
33,7 + 0,5°C
32,7 + 0,9°C
32,4 + 1,3°C
3
33,5 + 0,5°C
32,4 + 0,9°C
31,9 + 1,3°C
4
33,5 + 0,5°C
32,3 + 0,9°C
31,5 + 1,3°C
6
33,5 + 0,5°C
32,1 + 0,9°C
30,9 + 1,3°C
8
33,5 + 0,5°C
32,1 + 0,9°C
30,6 + 1,4°C
10
33,5 + 0,5°C
32,1 + 0,9°C
30,2 + 1,5°C
12
33,5 + 0,5°C
32,1 + 0,9°C
29,5 + 1,6°C
14
33,4 + 0,6°C
32,1 + 0,9°C
29,5 + 1,6°C
weeks
Particular cases in day 1
4
32,9 + 0,8°C
31,7 + 1,1°C
500 g. 35,5 + 0,5°C
5
32,1 + 0,7°C
31,1 + 1,1°C
1.00 g. 34,9 + 0,5°C
6
32,8 + 0,6°C
30,6 + 1,1°C
3.500 g. 32,8 + 1,2°C
7
31,1 + 0,6°C
30,1 + 1,1°C
4.00 g. 32,6 + 1,4°C
22
ABREVIERI
NN = newborn
EUN = neuro-necrotic enteritis
VG = gestation age
GN = birth weight
GTI = intern gradient
GTE = extern gradient
S = body surface
G = weight
Bibliography
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