Transport Incubator Research Articles

Historical Perspectives of Neonatal Transport

A personalized view of the growth and development of neonatal transport is presented. The public display of premature infants in France and Germany and the beginning of the transport incubators in Chicago are explained. How the policy of regionalization was developed and diluted during the readjustment phase is discussed.

Laboratory and flight tests of medical equipment for use in U.S. Army Medevac helicopters

When used in an air medical setting, medical equipment designed for use in hospitals can fail from the stresses of in-flight use, or they interfere with critical rotor-wing aircraft systems. From January 1989 to June 1992, 34 medical devices, including monitor/defibrillators, infusion pumps, vital-signs monitors, ventilators and infant transport incubators, were tested under extreme conditions of temperature, humidity, altitude and vibration (MIL-STD 810D). Electromagnetic emissions and susceptibility were measured (MIL-STD 461C and 462), and human factors were evaluated. The devices were flight tested in a UH-60 MEDEVAC helicopter. Thirty-two percent of the medical devices failed at least one environmental test, and 91% of the devices failed to meet electromagnetic interference standards. Failures included excess conducted and radiated emissions and susceptibility to radiated emissions. Five (15%) of the devices were judged unsuitable for use in the UH-60 MEDEVAC helicopter. Testing is critical to discover the ability of a medical device to perform in the harsh rotor-wing MEDEVAC environment. Failure of a device or interference with aircraft systems can result in loss of a patient or aircrew.

Hazard from the exposed terminals of a battery driven transport incubator.

Hazard from the exposed terminals of a battery driven transport incubator.

Higher energy-efficiency, readily transportable incubators

Transport incubators are devices used to house and protect premature or small babies individually during journeys between home and hospital or between hospitals, often in circumstances where the maintenance of comfortable environmental conditions within the incubators is essential for the survival of the infants. During use, the transport incubator has to frequently rely for its energy supply solely upon the storage capacity of a ‘built-in’ electric battery, which is the principal inhibiting factor limiting the available performance and duration of operation. During the present study of the environmental and engineering factors which affect the performances of such transport incubators, carried out for Air-Shields Vickers plc, consideration has been given to the use of two technologies to seek to improve both the quality of the artificially created internal environment in the incubator and the duration of operation independent of external electricity supplies. In particular, consideration has focused upon two possibilities: 1. 1. The use of a thermoelectric heat-pump (a) as a substitute for the conventional resistance heater within the incubator, so that the utilisation of the existing electric-battery charge would thereby be enhanced; and (b) to provide active refrigeration within the incubator without incurring the problems of noise and vibration normally associated with the presence of a compressor refrigerator. 2. 2. The potential for stored thermal energy to augment the energy-storage capacity of the electric battery. It has been shown that the use of a thermoelectric heat-pump can approximately triple the duration of use per electric-battery charge, as well as provide refrigeration cooling without incurring a significant weight penalty. The cost of the thermoelectric heat-pump is less than the additional expense incurred for the larger battery, which would otherwise be necessary to achieve the required operational duration. Also weight penalties would be involved in the use of a larger battery. Employing a supplementary thermal-store has been shown to be feasible and desirable, so that any heat lost during the permitted short-period, intermittent access to the incubator under adverse weather conditions can be ‘made good’ rapidly. This requires a very high but transient supply of heat.

Glucose transport in astrocytes: regulation by thyroid hormone.

Primary cultures of astrocytes from newborn rat brain showed evidence of a substrate-saturable process for glucose transport. The system shows a relatively high affinity for the substrate, with an apparent Km of approximately 1 mM. Maintenance of the cells in medium containing thyroid-hormone-free serum for 3, 6, or 9 days resulted in significantly reduced rates of hexose transport. Addition of exogenous triiodothyronine to the transport incubation medium of these "hypothyroid" cells markedly increased the net rate of 2-deoxyglucose uptake within 60 s to values equal to or above those of control cultures (cells maintained in normal serum). These findings support a key role for thyroid hormone in the transport of glucose across plasma membranes of brain cells and demonstrate the presence of this regulatory system in astrocytes.

A simple insulated cot for neonates

Commercially available transport incubators are sophisticated and expensive since they are designed to provide life support for premature or critically ill neonates. In maternity hospitals with inadequate heating systems, some healthy infants have difficulty maintaining their body temperature in wards and during transfer within the hospital. These babies do not require the sophistication of commercial incubators. We describe a simple insulated cot which meets these requirements at minimal cost.

1365 HYPOTHERMIA IN TRANSPORTED NEONATES: REWARMING EFFECT OF RADIANT HEAT VERSUS WARMED AIR INCUBATORS

Of 231 neonates transported to this centre in the last year 64 (28%) had a core temperature of< 36°C when examined prior to transport. Two types of transport incubator are in use; a conventional system with circulating warmed air (WA) and one using a radiant heat (RH) source. Allocation of incubators depends on availability and is largely random. Review of transport records shows 27 (42%) of the hypothermic infants rewarmed in transit with a rise in temperature above 36.5°C. 10 (25%) of the 40 infants nursed in WA units rewarmed and 17 (70%) of the 24 transported under RH. In cold babies WA unit environmental temperature is set 2°C above skin temperature and the skin servo of the RH unit at 36.8°C. Mean weights for rewarmed and persistently cold groups were comparable, as were time of day, season and mean duration of transport. Lowest incidence of rewarming was on short transports (<2 hours from initiating transport care to admission) In 2 infants who failed to rewarm core temperature was unrecordable prior to transport and with 2 others equipment malfunction occurred. 6 (20%) of those who remained cold in WA units actually lost body heat in transit. Neonatal mortality was 17% in the rewarmed compared with 37% among those who remained cold. Although initial morbidity and management are relevant, among hypothermic infants transported to this centre those nursed in radiant heat transport incubators appear to have a greater potential for rewarming than those in warmed air units, and those that do rewarm have a lower neonatal mortality than those who remain cold.

971 PROVISION OF NEUTRAL THERMAL ENVIRONMENT (NTE) DURING TRANSPORT

We studied thermal characteristics of a self-sufficient radiant heat transport incubator allowing intensive care in semi-open NTE in low external temperatures. Heat is provided by a transparent electrically heated semi-cylindrical hood which rotates over the bassinet. In the usual procedure mode (PM 1) the hood is partly rotated allowing access along one side and one end of the incubator. Other PMs are below. The lowest external temperatures at which NTE can be provided in each PM for 2 hours with use of the incubator battery pack were determined under laboratory conditions. Two designs were tested, differentiated by use of a Mylar screen (Design 2) spaced out 0.5cm from the hood's inner surface. In Design 1, infants weighing >2500 gms may inadvertently touch the hood whose inner surface can exceed 85°C. Constant observation by transport personnel eliminates this hazard. In Design 2, the Mylar screen's low thermal capacitance allows patient contact without concern for thermal damage. The results were: This radiant heat transport incubator will provide a semi-open NTE for at least 2 hrs. in low external temperature environments.

Evaluation of the Porta-Warm Mattress as a Source of Heat for Neonatal Transport

One risk of transport of newborns to referral centers is hypothermia. Modern transport incubators have limitations in their ability to keep infants euthermic. As tested in the laboratory and during actual transport the Porta-Warm mattress extends the capability of the transport incubator to keep neonates euthermic by (1) reducing the time required to warm the incubator and (2) warming the incubator in cooler environements. The mattress is an effective adjunct to the transport incubator for keeping newborns warm during transport.

Short communication

The transport incubator used since 1972 was modified for the CPAP method (continuous positive airway pressure). A very generous indication for the use of this ventilatory assistance in the presence of very early clinical signs of respiratory distress syndrome before or during the transport into the Children's Hospital has contributed towards improving the survival rate of infants with a birth weight of 1001-1500 grams to 84,8% and for those below 1000 grams to 39,4%.

Transport of newborn infants for intensive care.

During the three years 1972-4 222 newborn infants were transported to this hospital for intensive care. They were collected by trained staff using a specially modified transport incubator with an in-built mechanical ventilator and facilities for monitoring body temperature, heart rate, and inspired oxygen concentration. Two of the infants came from home and the rest from 41 hospitals from half a mile (0-8 km) to 50 miles (80-5 km) (median eight miles (12-9 km)) away. The mean birth weight of the infants was 1702 g (range 520-4040 g) and their mean gestational age was 32 weeks (range 24-42 weeks). The principal reasons for referral were low birth weight and severe respiratory illnesses. Altogether 109 (49%) of the infants needed mechanical ventilation in transit and another 38 (17%) needed it later. During the journey the condition of 88 (40%) of the infants was thought to improve, in 125 (56%) it was static and in nine (4%)--four of whom died--it deteriorated. A total of 142 infants (64%) survived the neonatal period. There was no correlation between the distance travelled and the survival rate. Seriously ill newborn infants may be transported safely to a referral centre within a radius of 50 miles, and the risks of the journey are negligible compared with the risks of leaving the infant in a hospital that is not staffed or equipped for neonatal intensive care.

Ambulance with intensive care facilities for the transport of infants at risk.

The present report deals with the results of a two year development program which had as its goal the improvement of transportation facilities f or the infant at risk, as well as minimization of the risk of transport for all participants. Pediatric or neonatal intensive care units within immediate proximity of delivery rooms provide the ideal conditions for resuscitation and continuation of intensive care of the asphyxiated newborn, according to v. LOEWENICH and BERG [3]. Nevertheless, considerable distance frequently separates the two, making it necessary to refer to a neonatal center those newborns whose vital functions remain in question after the primary resuscitation. A well-organized transport System for these critically ill newborns is seldom available, even though the need is obvious from an obstetrical as well as a pediatric standpoint. Unfortunately, as so often happens even today, the continuity of care in monitoring and treatment is interrupted by hasty, illprepared transport to the children's clinic in poorly heated transport incubators. If therapeutic procedures are eventually required during transport, the threat of hypothermia with associated hypoxia and acidosis becomes even greater. In this manner, initially successful resuscitative efforts can later be brought to naught.