Biomedical subjects

P M Macey

Publications and source records attributed to P M Macey.

4 recordsLinked to original sources

PubMed1997

The febrile stress of routine vaccination does not increase central apnoea in normal infants.

We tested the hypothesis that the febrile stress of routine vaccination would increase central apnoea in normal infants. Twenty-one normal infants had continuous overnight breathing and temperature recorded at home, before and after 58 routine vaccination episodes. Central apnoea, of at least 5 sec duration, was detected by computer algorithm and confirmed by human inspection. The longest recorded apnoea was 16 sec (n = 1) during 3629 h of sleep. Overnight rectal temperature increased after vaccination (median 0.52 degrees C, 95% CI 0.40, 0.65). Apnoea density reduced on 46/53 vaccination nights (median -29%, 95% CI -20, -37) followed by an increase on subsequent nights (median +10%, 95% CI +1%,+21%). Overall, apnoea density was similar during the 3 nights preceding and 4 nights following vaccination (median +1%, 95% CI +9,-6). The febrile stress of routine vaccination did not increase central apnoea in normal infants.

Body Temperature↗

PubMed1996

Breathing, sleep state, and rectal temperature oscillations.

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. Twenty one infants had continuous overnight rectal temperature and breathing recordings for 429 nights (mean 20.4 nights, range 7-30) spaced over the first six months of life. Periods when breathing was 'regular' were directly marked on single night records. Sleep state was determined from respiratory variables. 'Regular' breathing was a reliable marker of 'quiet' sleep (specificity 93%). The duration of 'quiet' sleep increased from 6 to 22 minutes from two weeks to three months of age and then remained static, as did the proportion of sleep spent in the quiet phase (9% to 34%). Rectal temperature fell during 66% of quiet sleep and usually rose during rapid eye movement (REM) sleep. The drop in rectal temperature was maximal at the start of quiet sleep, whereas the maximum rise during REM sleep was reached after 10 to 15 minutes. Oscillations in rectal temperature are associated with changes in sleep and breathing state. The maturation of rectal temperature patterns during the first six months of life are closely related to a maturation of sleep state and breathing patterns.

Aging↗

PubMed1995

Apnoea detection: human performance and reliability of a computer algorithm.

We examined the consistency of apnoea recognition between three human experts. The hypothesis was that computer detection of apnoea could emulate human expert apnoea recognition. The aim was to detect apnoeas with the highest possible accuracy from a single breathing signal, by both human experts and computer. Three human experts independently examined recordings of breathing wave-form from overnight sleep studies from 10 infants aged 3-17 weeks. All apnoeas of 5 s or more were identified and reviewed. However, there still remained 10% disagreement. A computer apnoea detector was implemented. An algorithm analysed statistical properties of the signal to find breathing pauses. Optimal performance was 1% missed apnoeas (compared with the agreed apnoeas identified by the three experts) and 29% false detections. This computer algorithm reliably identified most apnoeas but did not replace the human expert.

Algorithms↗

PubMed1992

HomeLog: long-term recording of infant temperature, respiratory and cardiac signals in the home environment.

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.

Apnea↗