No abstract

Overheating may cause terminal apnoea and cot death. Rectal temperature and breathing patterns were examined in normal infants at home during the first 6 months of life.

X-ray transmission tests were performed on a Green-Lite (Infab Corporation) apron/vest combination, and compared to a number of other apron/vest combinations routinely used at Christchurch Hospital as well as a sheet of 0.5 mm lead. The materials were X-rayed using the primary beam of a Philips Optimus 50 X-ray machine over an energy range of 50-125 kVp. The entrance and exit doses were recorded and percentage transmission calculated for each kVp. The Green-Lite apron/vest (labelled as 0.5 mm lead at 85 kVp) relies on the overlap at the front to provide the nominal 0.5 mm protection for both the vest and the apron. It performed significantly worse than 0.5 mm of lead and other 0.5 mm lead equivalent apron/vest combinations and provided between 0.3 and 0.39 mm lead equivalent protection depending on the energy used. Vests from other manufacturers all achieved 0.5 mm lead equivalence for a single layer of vest material over the range of energies tested and so were comparable to 1.0 mm lead when doubled. Some aprons relied on a double layer of material to achieve the 0.5 mm lead equivalence (which was not always made clear on the label), while others stated their lead equivalence for a single layer. This resulted in some confusion among wearers of the aprons as to which apron was better.

There is increasing evidence that overheating is a contributing factor for some cot Subjects and methods Our continuous temperature measurement studies were carried out in a hospital ward using a dedicated computer based polygraphic recording system (BabyLog).9 The ambient temperature ofthe hospital ward was 23-250C throughout these studies, and all infants were lightly clothed in the equivalent of a cotton vest and a nappy. Infants were enrolled if they were considered afebrile by their doctor, did not have an infectious or inflammatory illness, and had no known encephalopathy. Recordings were completed on 30 such infants who had presented with minor choking episodes for which there was no obvious cause found on polysomnographic study. Their ages ranged from 2 to 26 weeks. Ethics committee approval and written parental informed consent were obtained for these studies.The infants had continuous recordings of ambient and various body temperatures overnight for at least 12 hours. Rectal temperature was measured 5 cm from the anal margin and skin temperature from the forehead, axilla, wrist, abdomen, shin, and foot. We used temperature sensors which are based on a semiconductor rather than a thermistor. We have previously described the design, manufacture, and testing of these sensors, and the interface with our polygraphic recording system though a multiplexing isolating amplifier. 0 The multiple temperature channels were sampled once a second and the signal data were stored on the computer system for later analysis. Sleep state, feeds, nappy changes, and other behaviour were recorded on a diary sheet and by continuous video monitoring.Software has been written to produce a graphical output of the signal data and to allow measurement of any temperature recording at any sample point. Algorithms have also been developed for spectral analysis. " These software algorithms process the temperature data in the Fourier domain to produce a screen output with peaks corresponding to dominant oscillations. The frequency, and hence period, of each of these peaks is determined on screen. The largest peak corresponds to the dominant frequency for a particular recording.The temperature signals were than examined using the graphical software we have written for our system. Oscillations which varied in amplitude by more than 0-1°C were measured for the length of period from peak to peak. These measurements of each identifiable period were then averaged (with 95% confidence intervals) for each recording. ResultsThirty overnight studies have been examined in detail. Figure 1 presents an example of an overnight rectal temperature recording. Graphs of the continuous recordings showed trends on visual inspection that have been confirmed by further analysis. SLEEP-WAKE PATTERNSThe variation in rectal temperature over a single night was 0-4-0-7°C in the younger infants (less than 8 weeks old) but was as much as 1-5C in 1255 on 12 May 2018 by guest. Protected by copyright.

There is increasing evidence that overheating is a contributing factor for some cot deaths. The authors' hypothesis is that infant thermoregulation is closely related to respiratory control. HomeLog is a system built to investigate the developing thermal, respiratory and cardiac behaviour of infants in the home environment over several weeks. HomeLog is based on a modified laptop computer. Signals recorded include body temperature (from rectal and various skin sites), ambient temperature, thoracic impedance, abdominal movement and electrocardiogram (ECG). Continuous night-time recordings have been made for up to 6 weeks from infants between 1 and 4 months of age, in their own cots, in their own homes. Various time and frequency domain analyses of the breathing and temperature data have been developed. Analysis of breath rate variability and of body temperature fluctuations has confirmed sleep/wake changes. In addition, a periodic oscillation of body temperature every 1-2 h has been found, which closely matches oscillations of breath rate variability.