le. As in adult intensive care units, the use of monitoring and life support systems became routine. These needed special modification for small babies, whose bodies were tiny and often immature. Adult ventilators, for example, could damage babies lungs and gentler techniques with smaller pressure changes were devised.
Incubators for control of temperature and environment:
Temperature regulation in newborns.
One of the most important elements in a newborn's survival is the infants temperature regulation. Mammals have the advantage of being homeotherms, meaning that they are able to produce heat, allowing us to maintain a constant body temperature. However, homeothermy may be overwhelmed in extremes of cold or heat. The newborn baby has all the capabilities of a mature homeotherm, but the range of environmental temperature over which an infant can operate successfully is severely restricted.
The infant has several disadvantages in terms of thermal regulation. An infant has a relatively large surface area, poor thermal insulation, and a small amount of mass to act as a heat sink. The newborn has little ability to conserve heat by changing posture and no ability to adjust their own clothing in a response to thermal stress.
Responses may also be hindered by illness or adverse conditions such as hypoxia (below normal levels of oxygen). Heat exchange between the environment and the infant is like any physical object and its environment. Heat is exchanged by conduction, convection, evaporation, and radiation. Heat exchange by conduction is relatively small. Conduction depends on the thermal conductivity of a substance in contact with the body. Since babies are usually laid on a mattress, which has a relatively low thermal conductivity, the heat loss from the baby to the mattress is relatively small. Heat loss from the infant by convection is dependent upon air speed and air temperature.
Evaporative loss depends upon air speed and the absolute humidity of the air. If a baby is clothed or nursed in a regular warm air incubator of moderate humidity, evaporative heat loss is only a small fraction of the total heat lost by the infant. However, if an immature baby with thin skin is nursed under a radiant overhead heater in a normal nursery environment, evaporation is a major factor for heat loss. Radiant heat loss is slightly more complex than the rest. It is dependent on the surface area and geometry, the surface temperature of the body, as well as the temperature of the receiving surface area.
The infant's body responds differently to hot and cold temperatures. In the case of hotter environmental temperatures, the infant's body produces sweat through the sweat glands. The basal metabolic rate increases, causing the body temperature to rise. The risks of hyperthermia are great and should be attended to immediately. Serious overheating can cause heatstroke or death, and lesser degrees of stress can cause cerebral damage due to hypernatremic dehydration. Babies born more than 8 weeks before term have virtually no ability to sweat. Even in a baby born only 3 weeks early, sweating is severely limited and confined to the head and face. Sweat production matures relatively quickly in the pre-term baby after delivery, allowing the baby to be placed in a regular crib.
In the case of cold environmental temperatures, the infant may produce heat by shivering and other muscular activity. Cold stress is subtler in its consequences but must be attended to. Newborns may also be placed in a neonatal incubator.
A neonatal incubator is a device consisting of a rigid box-like enclosure in which an infant may be kept in a controlled environment for medical care. The device may include an AC-powered heater, a fan to circulate the warmed air, a container for water to add humidity, a control valve through which oxygen may be added, and access ports for nursing care. It may also contain a servocontrol to help regulate incubator air temperature. The servocontrol uses a temperature sensing thermistor, which is taped to the child's abdomen.
In infants born bef