comparative clinical evaluation of a prototype non...

f Comparative clinical evaluation of a

prototype non-electric transport incubator and an electrical infant

incubator in a neonatal unit

Y. Khodadadeh I F. Nili 2 F. Nayer i 2 Y. W i c k r a m a s i n g h e 1

1Centre for Science & Technology in Medicine, Keele University, School of Post Graduate Medicine, North Staffordshire Hospital, Stoke-on-Trent, UK

2Division of Newborn Medicine, Department of Paediatrics, Tehran University of Medical Sciences, Valiasr Hospital, Tehran, Iran

\

Abst rac t - -A new non-electric transport incubator has been developed for transferring babies between health facilities in developing countries. The temperature performance of this prototype was compared with a commercial electric incubator. The warm-up time for the prototype was 51.8 min, compared with 48.1 min for the electric incubator. Forty-five non-distressed premature babies, aged 24-72 h, with a gestational age of less than 37 weeks, were cont inuously evaluated for a 2 h period. Twenty-five babies, with a mean weight of 2073 g (range 1500-2500 g), were studied in the prototype, and 20 babies, with a mean weight of 2076 g (range 1550-2500 g), were studied in the electrical incubator. The rectal and abdominal skin temperature, heart rate, oxygen saturation and respiratory rate of the babies were recorded. The temperature, oxygen and humidi ty level of the canopy and the room temperature were also measured. The Sa02, heart rate and respiratory rate were within the normal range (in the prototype: 96.5%, 130.5 beats min 7 and 43 breaths min 7, respectively; and, in the electric incubator: 96.5%, 128.5 beats min 7 and 40 breaths min 7, respectively). No evidence of carbon dioxide narcosis, hypoxia, acidosis or adverse thermoregulatory behaviour were observed in the two groups. The mean rectal temperature for both groups was within the range 36.5°C-37.5°C. There was no signif icant difference between the measurements of the two groups. The level of oxygen inside the canopy was 21%, and no decrease was observed. The new non- electric transport incubator conf irmed its safety and efficiency in providing a warm environment for non-distressed premature babies over a 2 h period.

Keywords--Appropr iate technology, Hypothermia, Incubator care, Thermal control device, Premature infant, Thermoregulation

Med. Biol. Eng. Comput., 2001, 39, 594-600

J

1 In t roduct ion

THE IMPORTANCE of maintaining a favourable thermal environment for newborn infants is well documented (SINCLAIR, 1992). Weight gain and growth in length and head circumference can be affected by cold stress (DUCKER et al., 1985). Neonatal hypothermia contributes to high mortality and morbidity (WHO, 1992). in many countries, the incidence of hypothermia is unknown, owing to a shortage of information caused by a lack of awareness of the problem (SARMAN et al., 1989).

When it is necessary to transfer a baby, it is important to keep it warm during transportation (MALHOTRA e t al., 1992). in rural areas of developing countries, deliveries occur mainly at home or in village health centres. Clinical facilities and trained

Correspondence should be addressed to Dr Y. Wickramasinghe; emaih [email protected] Paper received 12 December 2000 and in final form 16 July 2001 MBEC online number: 20013610

© IFMBE: 2001

personnel are scarce. The only way that ill babies in that situation can survive is by being transferred to suitable facilities in bigger towns or cities, but during transportation they become even colder. Also, in the towns and cities of developing countries, when there is a need for transferring babies between hospitals or from home to hospital, the infants can become very cold during transport. Therefore the provision of a safe and warm environment for transportation is essential for the babies to survive the journey.

The uterus is an ideal transport device for a baby (WHO, 1986). As approximately 40% of risk pregnancies cannot be detected until the beginning of labour (CHANCE, 1978), it can be necessary to transfer babies after birth to a nearby health care facility. Various methods have been developed for keeping babies warm during transport, such as the Kangaroo method (BAUER et al., 1997), transparent baby bag (BESCH et al., 1971), silver swaddler (BAUM and SCOPES, 1968). Porta-warm mattress (NIELSEN et al., 1976) and water-filled mattress (SARMAN e t al., 1993). Although they are effective to some degree, observation of the baby for respiratory distress, apnoea, bradycardia, intra- venous leak, etc. is compromised (MALHOTRA et al., 1992).

594 Medical & Biological Engineering & Computing 2001, Vol. 39

A form of insulated box for keeping babies warm during transport has been developed in China and india (MALHOTRA et al., 1992). A healthcare device manufacturer* has designed non-electric transport incubators. The most successful device has been developed by LEMBURG (1985) and is heated by a container of hot water (WHO, 1986). Owing to its simple construction and the ready availability of hot water, this apparatus is in use in several countries, especially in South America. its only disadvantage is that the temperature may need to be controlled by an untrained user.

At present, the most common form of transport thermal control device is the transport incubator. Such devices can use direct current (DC) from the vehicle during the transfer of the baby. Most developing countries are unable to afford the high costs of transport incubators and do not have sufficient trained personnel to supervise their use and maintenance (WHO, 1986). As transport incubators are not affordable for developing countries, only a few exist in private hospitals or for special cases in public hospitals. Thus, most babies requiring transfer are wrapped in a blanket and taken by car or ambulance.

A need was felt for a safe, cheap and effective transport incubator for transferring babies between health facilities in developing countries, and a simple, non-electric transport incubator was designed and developed. The aim was for the device to achieve a steady temperature of 35 -4- 2 °C in the baby's compartment, at ambient temperatures between 5 °C and 30 °C, for a minimum of 2 h (this study was conducted in a hospital ward). The differences in temperature between the various points of the baby's compartment should not exceed 2 °C. A safe and reliable method was needed for controlling the heat within the canopy and for protection against overheating. There should be sufficient airflow within the canopy to maintain the oxygen concentration at the normal level of 21%. The warm-up time should be comparable with that of an electrical incubator.

The main aim of the present study was to assess the technical feasibility, efficiency and safety of the prototype by comparing it with an air-heated electrical incubator in routine use in the hospitals of Tehran. These studies were carried out within hospital wards and not under transport conditions.

2 Materials and methods

2.1 Prototype

A simple, non-electric transport incubator was designed at Keele University, by Yassaman Khodadadeh in collaboration with the Ministry of Health of Iran. The prototype was developed and tested under different conditions in the laboratory. The device produces heat via an exothermic crystallisation reaction initiated by a metal disc (KHODADADEH and ROLFE, 1998), similar to that used by commercially available hand warmers. This system is reusable.

The dimensions of the new prototype are 60 x 30 x 30 cm. The prototype is made of two layers of Plexiglas filled with polyurethane foam for insulation. Polyurethane foam is classified as a good insulation material with low thermal conductivity. Plexiglas is physiologically harmless and is resistant to bacteria, acid and alcohol. The chemical bags are placed in the back wall of the prototype. To have better access to the chemical bags, there is a door in the back of the prototype.

The front door is made of transparent Plexiglas, so that the baby can be observed, it is double-glazed and contains two ports for access to the baby. The front door is not airtight, enabling ventilation to take place. Two holes are provided in the sides of the door for inserting any leads or a serum tube. To prevent overheating, there are two small ports that open automatically when

*Drager

Medical & Biological Engineering & Computing 2001, Vol. 39

Table 1 Number of chemical bags" required for diffbrent ambient temperatures providing 35 ± 2 ° C in canopy

Ambient temperature, °C 5-10 10-15 15-20 20-25 25-30 Number of chemical bags 25 18 12 8 4 required

the inside temperature rises to about 38-39 °C and, hence, cause a decrease in temperature. A shape-memory alloy causes the automatic opening of each port (Fig. 1). The level of heat in the prototype is controlled by the number of chemical bags intro- duced. A theoretical thermal model was developed prior to this study to estimate the number of chemical bags required for different ambient temperatures. The details are presented in Table 1.

2.2 Electrical incubator

The electrical incubator used in this study for comparison was a Tosan incubator made in Iran. The Tosan incubator is the most common, if not the only, incubator in use in the hospitals ofiran. it is air heated, single walled and manually controlled (Fig. 2). its temperature can be adjusted between 28 and 38 °C. it is equipped with alarms for overheating and failure of the fan. it is made for use in hospitals and not for transport and can be used in ambient temperatures between 20 and 30 °C. As there is no transport incubator in most of the hospitals of Tehran, this type of stationary incubator was used for comparison with the prototype. The prototype was studied in the hospital instead of under transport conditions. The electrical incubator used in this study was retained by the unit as a spare, it was serviced by a technician of the Tosan Company and checked for accuracy before the study.

2.3 Patients and methods

The study was performed in the neonatal care unit of the Valiasr hospital, Tehran, from December 1999 to May 2000. it included non-distressed infants weighing between 1500 and 2500 g, aged between 24 and 72 h and with a gestational age of less than 37 weeks, who had no respiratory distress. Hypothermic babies were not included in this study. The gestational age of the newborn infants was evaluated by the Ballard method. The Ethics Committee of the Ministry of Health, Iran, approved the protocol. After obtaining informed consent from the parents, 45 babies who fulfilled the above criteria were randomly assigned for study, either in the prototype (n = 25) or in the electrical incubator (n = 20). The babies were placed inside the incubator after feeding and having had their nappies changed. The neonates were naked except for a nappy in both groups.

A low-reading, mercury-in-glass thermometer t was used to measure the rectal temperature of the babies before and after each study. The thermometer was checked for accuracy against a standard thermometer * using a water bath. The temperature was checked between 25 °C and 40 °C. The thermometer was gently inserted 3 cm into the rectum (WHO, 1993) and was removed after 3 min. A skin temperature probe,** with self-test and calibration facilities, was attached to the right upper quadrant of the abdomen (liver area). The probe of a self-calibration

x t r O ypleth pulse oximeter monitor with a flexible neonatal

tBS691/SB1 A C8 Philip Harris Medical, Zeal, England

~Type BS593 A40C, manufactured by LSW, with certificate number 5852 **Ameda AG/Amanic, Switzerland ttModel 520A, Novametrix Medical System Inc., USA

595

humidity sensor chemical bags

main door oxygen probes

Fig. 1 Prototype during studies in hospital

temperature probes port babytray

canopy humidity sensor oxygen probes ports main door baby tray

Fig. 2

596

humidity control knob

Electrical incubator used in studies

temperature probes power alarm switch indicator


A =

B~--

C~

m - . . ~ D

m . - . ~ E

Fig. 3 Schematic diagram of top view of mattress, showing positions of probes

probe was attached to the right foot to monitor the pulse rate and oxygen saturation.

The pulse rate, SaO2, respiratory rate and skin temperature of the baby were recorded every 5 min manually. A data logger (TC-08) was used to store measured temperature, oxygen and humidity levels inside the incubator. These data were acquired at 1 min intervals. The data logger had eight channels. The accuracy of the data logger and eight thermometers was checked in a water bath at nine different temperatures (0, 5, 10, 15, 20, 25, 30, 35, 37 °C) against the standard thermometer. Five tempera- rare probes were placed in the canopy according to the British Standard (BS 5724, 1997). The probes were placed 10 cm above the mattress, at the centre of the canopy and at the centres of four assumed rectangles, on every side. A schematic diagram of the top view of the mattress is shown in Fig. 3 to indicate the five standard points where the probes were placed. These points were named A, B, C, D and E. The placement of the probes is also shown in Figs 1 and 2. Probe 6 measured the air temperature of the room. Channel 7 was used for recording humidity through a Vasala HMI31 with Humicap humidity sensor (made in Finland). The sensor was placed in the middle of the back of the canopy, 10 cm above the mattress. There was no humidifier in the prototype or in the Tosan incubator. Although Tosan incubators are equipped with a humidifier, to prevent infection it is not used routinely, but only for special cases, such as very low birth weight babies or after extubation. Channel 8 was used for recording the oxygen concentration level. The probe to measure the oxygen concentration level was placed to the left-hand side of the back of the canopy, 10 cm above the mattress. An oxygen analyser ** was also used to monitor the level of oxygen. The oxygen probe of the analyser was placed at the right-hand side of the back of the canopy. The accuracy of the device was checked against a standard oxygen meter. The temperature of the chemical bag was also measured in some of the tests (as can be seen in Fig. 6).

Obviously, thermal conditions are not the same in hospital as in a transport situation. During transport, the incubator is placed in an ambulance, which is at a lower temperature than the hospital, it may also be necessary for the incubator to pass through an area of very low temperature between the building and the ambulance.

For most studies, the temperature of the prototype and of the electrical incubator was set at 35 °C. For a few studies, it was adjusted to 31-33 °C for babies who required a lower temperature as judged by the paediatrician. The average room temperature for the studies with the prototype was 21.7°C (range: 16-27 °C) and for the studies with the electrical incubator it was 25.3 °C (range: 20-30 °C). The temperature difference was due to the fact that the studies with the prototype were carried out in a separate room in the neonatal trait. The ports or the main door of the prototype and the incubator were opened for routine tasks of the nursery, such as feeding the baby, adminis- tering drugs and taking blood samples. The wall temperature of

$$TED 200 from Teledyne Brown, USA


the incubators and the air speed inside the incubators were not measured.

Each baby was continuously observed. General behaviour, activity, colour and excessive crying were recorded. Although the temperature of both the electrical incubator and the prototype and the level of the oxygen inside the canopy were measured continuously during the study, the investigators decided the study should be terminated if any of following four conditions occurred:

(i) the skin temperature decreased below 35.8 °C (ii) the SaO2 decreased by 5% or it fell below 90% (iii) the pulse rate increased to over 180 beats min 1 (iv) the respiratory rate increased by 25%.

Both the Tosan incubator and the prototype were cleaned with soap and water and Javelle water after each test and were left to dry for 4 h. Prior to re-use, they were re-sterilised with 76% alcohol. The smell of alcohol was removed by leaving the door of the incubator open for 5 min. The chemical bags were boiled after each test to change them to the liquid state for reuse. After boiling, they were kept in a sterilised container. To prevent infection, disposable plastic covers were provided for the chemical bags. Before placing the chemical bags in the prototype, they were put in the disposable plastic covers.

Statistical analysis was carried out using a one-sample t-test, a two-samples t-test and a paired t-test. Ap-value of less than 0.05 was considered significant. Analyses were performed using SPSS computing software.

3 Results

3.1 Technical evaluation

The time taken for the transport incubator temperature to rise by 11 °C is defined as the warm-up time (BS 5724, 1997). The transport incubator temperature refers to the temperature of the air at a point 10cm above the centre of the mattress surface in the baby compartment. The desired temperature inside the canopy was 35 °C. The average length of time for the prototype air temperature to reach a steady state was 51.8 min (SD : 3.9) and, for the electrical incubator, it was 48.1 min (SD : 6.9). Fig. 4 shows typical graphs of the warming-up time for the prototype and the electrical incubator. The results of the technical evaluation are summarised in Table 2.

~- 30

60 120 time, min

a

. . . . . . incubator temperature

i 180

- - ambient temperature

30

,

60 time, min

b

i 120

Fig. 4

i 180

. . . . . . incubator temperature ambient temperature

Typical graphs of warm-up time of (a) prototype and (b) electrical incubato~ In each graph the lower trace represents" ambient temperature

597

Table 2 Results o f technical evaluation o f prototype and electrical incubator

Prototype Electrical incubator

95% confidence interval of difference

Results of technical evaluation lower upper lower upper p-value

Warm-up time, min 49.3 54.4 43.7 52.5 NS ATof steady state, °C 0.88 1.11 0.82 1.12 NS Difference of 5 points, °C 0.92 1.14 1.03 1.31 NS

The differences in the maximum and the minimum air temperatures inside the canopy during the steady state in each study were calculated. The mean difference in the temperature AT for the prototype in 25 studies was 0.99 °C (SD = 0.3) and, for the electrical incubator in 20 studies, it was 0.97°C (SD = 0.3). The difference between the two groups was statis- tically non-significant.

The difference in the maximum and minimum temperatures between the five temperature probes was calculated for each minute. The mean difference in the temperature between different points o f the prototype in 25 studies was 1.05 °C (SD = 0.28) and, for the electrical incubator in 20 studies, it was 1.19°C (SD =0.33).

The oxygen concentration level inside the canopy did not decrease during the studies and was always 21% in both the prototype and in the electrical incubator. The relative humidity inside the prototype and inside the electrical incubator was recorded every minute. There was no humidification facility in the prototype, and the electrical incubator was run dry. The humidity measured in the study varied owing to environmental factors such as rain. During the study, the heat o f the incubators caused a decrease in the level o f the humidity.

Opening the ports or the main door caused a decrease in the temperature o f the canopy, it took some minutes for the temperature to recover to the level attained before the ports or the main door were opened (recovery time). The average fall o f the temperature readings as a result o f the ports and the main door being opened are presented in Table 3. An example o f a typical temperature graph relating to the opening of the ports and the door of the prototype and the electrical incubator is presented in Fig. 5. The dips seen in the room temperature in Fig. 5 (electrical incubator graph) are due to various environmental conditions, such as doors being left open in the ward. This is not seen in the prototype graph, as that study was carried out in a separate room. As the graph shows, when the door was opened, two temperature probes showed a larger fall in temperature than the others. These were points A (centre) and E. The factors contributing to this were the location o f the sensors (one close to the door) and the air circulation. Fig. 6 gives a full temperature profile within the prototype incubator, showing the warm-up, steady state and the fall off.

o O 40ropening main door opening ports opening main door - . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .................................................. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

o_ 2 0 F . . . . . I= 151 , , , ,

60 90 120 150 180 time, min

a - - point A (Centre) . . . . point B ............................. point C

point D ................... point E ambient

oO ,, opening main door ~opening ports

2 0 ~ - - - - & 1 0 1 - E 01 , , , , , , ,

40 60 80 100 120 140 160 180 time, min

b - - point A (Centre) . . . . point B ~ point C

............... point E - - a m b i e n t

Fig. 5 Typical graph o f efJbcts on temperature o f opening ports" and main door in (a) prototype and (b) electrical incubato~ In each graph the lower trace represents ambient temperature

o 60 F ~-s0rr N 40[ - /

30 I-_l~"-- ~ 2 o r E 1 0 1 -

chemical bag !

~ambient temperature I I

6'0 ' ' 120 180 240 300 time, min

point A - - (centre) . . . . . . point B . . . . . point C . . . . point D . . . . . point E ambient chemical bag

Fig. 6 Typical graph of warming-up, steady-state and cooling-down times o f prototype using eight chemical bags"

3.2 Physiological validation

All 45 babies were studied for at least 2 h, and none of them had to be excluded from the study. The babies were comfortable both in the prototype and in the electrical incubator. They sometimes cried owing to hunger and voiding urine or stools. SaO2, pulse rate and respiratory rate were within normal ranges.

The rectal temperature was measured at the beginning and at the end of the study. Although the continuous measurement o f rectal temperature is preferred, this was not possible owing to the use of a mercury-in-glass thermometer. The mean rectal temperature was similar in both groups, and it was within the normal range, between 36.5 and 37.5 °C (WHO, 1993). There was no significant difference between the measured temperatures at the beginning and at the end of the studies. The results are presented in Table 4.

The average skin temperature o f the babies studied in the prototype was 36.1 °C (SD = 0.56) and, of the babies studied in the electrical incubator, it was 36.2 °C (SD = 0.43). There was no significant difference between the measurements of the skin temperature in the two groups, and they were within the normal

Table 3 Opening ports" and main door o f prototype and electrical incubator

Opening time, Recovery time, Temperature Ambient min min decrease, °C temperature, °C

mean (SD) mean (SD) mean (SD) mean (SD)

Prototype ports 3.22 (1.20) 3.67 (0.87) 2.10 (0.55) 22.0 (2.00) Incubator ports 2.61 (0.78) 3.39 (0.70) 2.79 (1.91) 23.6 (4.10) Prototype door 1.94 (0.77) 2.94 (0.95) 3.44 (1.89) 22.6 (2.24) Incubator door 1.93 (0.84) 2.93 (0.73) 3.15 (1.44) 25.4 (2.64)

5 9 8 M e d i c a l & B i o l o g i c a l E n g i n e e r i n g & C o m p u t i n g 2 0 0 1 , V o l . 39

Table 4 Comparison of rectal temperature o f babies in both groups

Prototype Electrical incubator p-value (n -- 25) (n -- 20) start and end

start end start end prototype/ Study duration, 2h mean (SD) mean (SD) mean (SD) mean ( S D ) incubator

Rectal temperature, °C 36.7 (0.80) 36.7 (0.49) 36.8 (0.48) 36.8 (0.33) NS/NS

Table 5 Results o f physiological measurements" in both groups

Prototype Electrical incubator

95% confidence interval of difference

Results of physiological measurement lower upper lower upper p-value

Skin temperature, °C 35.9 36.3 36.0 36.4 NS SaO2, % 96 97 96 97 NS Pulse rate, beats min 1 127 134 125 132 NS Respiratory rate, breaths min 1 39 47 36 44 NS

range (RUTTER, 1999). The physiological measurements are summarised in Table 5.

The SaO2 measured during the study varied from 92% to 98%, which is within the normal range (HAY e t al., 1991). The average SaO2 for the babies studied in the prototype was 96.5% (SD = 1.37) and, for the babies studied in the electrical incubator, it was 96.5% (SD = 1.12). The mean pulse rate for the babies studied in the prototype was 130.5 (SD = 9.29) and, for the babies studied in the electrical incubator, it was 128.5 (SD = 7.26). Therefore it can be said that the pulse rate measured during the study varied within the normal range of 100-180 beats mill -1 (GOMELLA, 1999).

The average respiratory rate for babies studied in the prototype was 43 breaths min -1 (SD = 9.70), and, for the babies studied in the electrical incubator, it was 40 breaths mill -1 (SD=9.11). Therefore the respiratory rate measured during the study varied within the normal range of 30-60 breaths mill -1 (GOMELLA, 1999).

4 Discussion

This paper describes the development and initial testing of a non-electric transport device. The technical evaluation of the prototype showed that the warm-up time was comparable with that of the electrical incubator. The prototype maintained the temperature for 2 h. Our device is easy to use and control and has a reliable and reusable non-electric source of heat. It is possible to maintain heat at the desired level in varying ambient temperatures by using different numbers of chemical bags. i f the seal of the container of the chemical breaks, the liquid chemical changes to solid automatically in less than 3 s. The chemical bags are placed in disposable plastic bags before insertion into the incubator, which further reduces the risk of any leakage into the incubator.

The prototype maintained its temperature when the ports were opened for access to the baby for routine tasks. The ambient temperature and the length of time that the door or ports were opened influenced the temperature decrease and the recovery time. Opening the main door in both the prototype and the electrical incubator caused a greater decrease in temperature than the opening of the ports. Conversely, exposure of the incubator to the sun would allow short-wave radiation to pass through the Plexiglas to overheat the baby. Therefore it is very important to


train personnel in the proper use of the device. Good insulation of the prototype prevents heat loss.

The design philosophy of the prototype is based on generating a small amount of heat and preserving this heat by proper insulation (KHODADADEH and ROLFE, 1998). Although there was no fan for distributing the warm air, the air circulated in a natural way, and the temperature difference between the five different points of the prototype was less than 1.5 °C.

The chance of survival for premature babies increases under a higher humidity because of a decrease in water loss through evaporation (SILVERMAN and BLANC, 1975). An association between higher humidity and higher infection rates in the newborn nursery has been reported, and some neonatal care units prefer to run incubators dry and use the humidifier for extremely sick premature babies, judged on an individual basis (CHAO et al., 1989). However, the humidification facility is important for the incubator. Our prototype presently has no humidity facility, and this will need to be considered in further designs.

The results of the physiological measurements show that the babies' body temperature (rectal and abdominal skin), SaO2, heart rate and respiratory rate varied within the normal range, it is important that a baby is clinically stable before transfer (DEVANE, 1999). The new non-electric transport incubator is cheap, easy to use, easy to maintain and repair and has confirmed its safety and effectiveness in keeping non-distressed babies warm. The prototype was able to maintain a constant and well- distributed temperature for 2 h, and the results were comparable with those of the electrical incubator, it would be possible to administer oxygen into the canopy if required.

The new non-electric incubator is suitable for transferring babies from rural and isolated areas to bigger towns or cities, between health facilities in a town or for indoor transport between different units of a hospital. Also, in the event of delivery occurring in a cold room in the health centre of a village, it would be possible to place the baby in the device immediately after birth, until the mother was able to embrace and breast-feed the baby. The incubator can be warmed up and kept ready to receive a newborn baby.

The ambient temperature range specified for commercial transport incubators is 10-30 °C, and the performance of the prototype at low ambient temperatures will be examined. Further studies are needed to evaluate the performance of the prototype in ambulances and field trials including long journeys. Studies will include placing hypothermic babies in the prototype and

599

obtaining data regarding their warm-up, it is l ikely that the new device will meet the requirements o f the appropriate technology (WHO, 1982).

Acknowledgments" The authors acknowledge the support o f staff at the Neonatal Units at Valiasr Hospital, Dr Roya Pirzadeh, Dr Reza Majdzadeh and Mr Kakaey for their advice and consulta- tion, and the staff at the Centre for Science & Technology (CSTM), Keele, including Y. Khodadadeh 's previous super- visor Dr Rolfe. Thanks are also extended to Gretta Bloor of the CSTM for her help with the preparation of this manuscript.

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Author's biography

YASSAMAN KHODADADEH is an Iranian Design Engineer. She received her MSc from the Centre for Science & Technology in Medicine, Keele University, in 1994. Her field of interest is appropriate technology for developing countries. She has recently submitted her PhD thesis entitled 'Design and development of a new non-electric thermal control device for keeping babies warm during transport in developing countries'.

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comparative clinical evaluation of a prototype non...

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