Biomedical subjects

S E Wilcock

Publications and source records attributed to S E Wilcock.

7 recordsLinked to original sources

PubMed1997

Correlation between 99Tcm-HMPAO-SPECT brain image and a history of decompression illness or extent of diving experience in commercial divers.

OBJECTIVES: To explore the use of 99technetiumm-hexamethyl propylene amine oxime single photon computed tomography (HMPAO-SPECT) of the brain as a means of detecting nervous tissue damage in divers and to determine if there is any correlation between brain image and a diver's history of diving or decompression illness (DCI). METHODS: 28 commercial divers with a history of DCI, 26 divers with no history of DCI, and 19 non-diving controls were examined with brain HMPAO-SPECT. Results were classified by observer assessment as normal (I) or as a pattern variants (II-V). The brain images of a subgroup of these divers (n = 44) and the controls (n = 17) were further analysed with a first order texture analysis technique based on a grey level histogram. RESULTS: 15 of 54 commercial divers (28%) were visually assessed as having HMPAO-SPECT images outside normal limits compared with 15.8% in appropriately identified non-diver control subjects. 18% of divers with a history of DCI were classified as having a pattern different from the normal image compared with 38% with no history of DCI. No association was established between the presence of a pattern variant from the normal image and history of DCI, diving, or other previous possible neurological insult. On texture analysis of the brain images, divers had a significantly lower mean grey level (MGL) than non-divers. Divers with a history of DCI (n = 22) had a significantly lower MGL when compared with divers with no history of DCI (n = 22). Divers with > 14 years professional diving or > 100 decompression days a year had a significantly lower MGL value. CONCLUSIONS: Observer assessment of HMPAO-SPECT brain images can lead to disparity in results. Texture analysis of the brain images supplies both an objective and consistent method of measurement. A significant correlation was found between a low measure of MGL and a history of DCI. There was also an indication that diving itself had an effect on texture measurement, implying that it had caused subclinical nervous tissue damage.

Adult↗

PubMed1996

Decompression illness in sports divers detected with technetium-99m-HMPAO SPECT and texture analysis.

UNLABELLED: Diving for sport and recreation has increased in recent years, resulting in more incidences of diving illness. Therefore, we studied potential use of regional cerebral blood flow SPECT imaging with 99mTc-HMPAO in the management of divers who have experienced decompression illness (DCI). METHODS: A group of ten sports divers who had no experience of DCI were compared with ten sports divers who had experienced at least one episode of DCI. Transaxial SPECT images were first compared objectively using a first-order texture measure and then subjectively using a receiver operator characteristic (ROC) experiment. Experienced observers were asked to rate images subjectively in terms of the images' textural appearance. RESULTS: Both these techniques showed that there is a statistically significant difference between the two groups and the images produced by the DCI divers were generally more coarsely patchy when compared to the non DCI divers. The quantitative texture technique proved significantly better in identifying divers with DCI than the visual analysis by observers using ROC curves. CONCLUSION: Differences between the cerebral blood flow patterns of sports divers who have experienced DCI and sports divers who have no experience of DCI can be detected using 99mTc-HMPAO SPECT and a texture analysis technique.

Adult↗

PubMed1995

Texture analysis of divers' brains using 99Tcm-HMPAO SPET.

The potential use of regional cerebral blood flow (rCBF) single photon emission tomography (SPET) imaging with 99Tcm-hexamethylpropyleneamine oxime (HMPAO) in the management of divers who have undergone a form of decompression sickness (DCS) was investigated using texture analysis. We imaged 50 divers, 10 of whom had only experienced DCS which had been categorized as Type 1, 20 of whom had a history of DCS classified as Type 2 and 20 of whom had not suffered an episode of DCS. A number of divers who had experienced Type 2 DCS had also had incidents of Type 1. The reconstructed SPET images were pre-processed and analysed using a first-order texture analysis technique based on a grey level histogram. The results showed that there was a significant textural difference between the divers who had only suffered episodes of DCS Type 1 and the diving controls and a difference between the divers with a history of Type 2 and the diving controls. No differences were found between the two groups of divers who had a history of DCS. This result suggests that DCS produces a detectable change in 99Tcm-HMPAO SPET brain images. However, the segmentation between the groups investigated was not complete and so the usefulness of this approach appears limited in individual cases but may provide useful information about the effects of different diving practices.

Adult↗

PubMed1988

A computer program to calculate mean skin temperature from measurements available from field trials.

Attempts to estimate mean skin temperature for subjects during prolonged experiments in field conditions are often made difficult because probes become disconnected or cease to function. There are several equations which allow estimation of mean skin temperature from a reduced number of functioning probes. The Fortran program described chooses the appropriate equation, calculates the mean skin temperature using whichever readings are available from the six selected sites and calculates mean body temperature using also rectal temperature. The organization of the program is such that it could easily be modified for use on results from a wide range of experimental conditions.

Electronic Data Processing↗

PubMed1988

Medical evacuations from offshore structures.

A retrospective study was carried out on medical evacuations from the installations of four major oil or gas producing companies, or both, operating offshore on the United Kingdom continental shelf. The study covered 1976-84 during which 2162 evacuations were recorded. Of these, 137 (7.7%) required the use of a chartered helicopter. In the earlier years of the study there were substantially more injuries sustained than episodes of illness recorded but from 1980 onwards the cases of illness equalled those of injury. Using the International Classification of Diseases, the digestive system was responsible for most evacuations for illness and of those, about half (115 evacuations) were for dental problems. Suspected fractures were responsible for about one third of those evacuated for an injury but injuries of hands and eye conditions were particularly common, accounting for 25% of all evacuations. As the age of the evacuee increased the proportion of evacuations for injury decreased and that for illness increased. The mean age for evacuation for injury was 28.3 years and for illness 34.4 years. Few evacuations were required for those aged over 45.

Accidents, Occupational↗

PubMed1985

Cold and performance: the effects of information load, analgesics, and the rate of cooling.

In the first experiment, 8 subjects took part in two experimental sessions--one after receiving one of two kinds of analgesic and the other after receiving a placebo. For each session, subjects completed 8- and 4-choice versions of a serial choice reaction time (SCRT) task at three times: before, during, and after exposure in a cold room at -5 degrees C. Body temperatures were monitored throughout and comfort ratings were recorded. The results indicated that cold increased error rate on the SCRT task, particularly for the 8-choice version which was also associated with faster RTs. However, a speed-accuracy tradeoff explanation for the data was discounted on the grounds that, although overall latencies were faster in the cold compared with precold, these were no faster than postcold RTs. The analgesics had no effect on comfort nor did they have an interpretable effect on performance. In experiment 2, where cooling was much slower for 5 subjects, no such increase in error rate on the SCRT task was observed. Similarly slow cooling did not impair general intellectual ability as measured by Raven's Progressive Matrices.

Adult↗

PubMed1980

Environmental and body temperatures of 52 divers in hyperbaric heliox.

Rectal and skin temperatures were recorded over periods as long as 24 h on 52 divers at depths as great as 300 m. Chamber temperature and body temperatures are correlated with depth, and the correlation between chamber temperature and mean skin temperature is evaluated. To ensure thermal balance daytime chamber temperatures must change with depth in meters according to the relationship Tch = 28.23 +/- (0.0058 x depth). Nighttime chamber temperatures must change according to the relationship Tch = 27.6 + (0.0074 x depth). Daytime rectal temperatures change significantly with depth in a way described by a 2nd-order regression line. The linear rate of change is 0.0014 degrees C/m increasing from a sea level value of 36.62 degrees C in heliox. Daytime mean body temperature increases with depth by 0.001 degrees C/m from 35.3 degrees C. Daytime mean skin temperatures very with chamber temperature at a rate of 0.34 degrees C/degrees C, which is identical to that found for an unclothed person in 1 ATA air.

Atmospheric Pressure↗