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Biomedical subjects

I M Whyte

Publications and source records attributed to I M Whyte.

60 records · Page 4Linked to original sources
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The assessment and treatment of theophylline poisoning.

Theophylline poisoning long has been recognized as difficult to treat and still has an over-all mortality rate of about 10%. In recent years, the increasing use of sustained-release preparations has changed the pattern of toxicity. The management of theophylline toxicity is compounded by clinical differences between chronic (overmedication) intoxication and acute single ingestions of a large amount of the drug, inter- and intraindividual variability in theophylline metabolism and dose-dependent kinetics in poisoned patients. Management decisions should be based on both clinical assessment and laboratory information (particularly theophylline concentrations).

Charcoal↗
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Lymphatic flow rates and first-aid in simulated peripheral snake or spider envenomation.

OBJECTIVES: To demonstrate and define normal lymphatic transit times by lymphoscintigraphy and to evaluate the efficacy of the currently recommended first-aid measures for the management of snake or spider envenomation. SETTING: The nuclear medicine department of a major teaching hospital. PARTICIPANTS AND DESIGN: Twenty-four subjects received either intradermal or subcutaneous injections of 99mtechnetium antimony sulfur colloid (0.1 mL) in both hands/forearms and feet/legs. This simulated a snake or spider bite. Fifteen of the subjects had first-aid in the form of firm bandages and splints applied to an upper and a lower limb immediately after injection. MAIN OUTCOME MEASURES: The progress of the radiotracer was followed with a large field of view gamma camera. If no egress of radiotracer was seen in the bandaged limbs, the subject walked until radioactivity was detected. RESULTS: The mean (+/- SEM) periphery-to-systemic circulation transit time after subcutaneous injection was 58 (+/- 7) minutes. The first-aid was found to be very effective when applied with bandage pressures ranging from 40 to 70 mmHg (5.3-9.3 kPa) in the upper limb and 55 to 70 mmHg (7.3-9.3 kPa) in the lower limb. Lower and higher bandage pressures were ineffective. However, despite first-aid measures, egress of radiotracer, even in the upper limbs, was seen in all subjects who walked for 10 minutes or more. CONCLUSIONS: Firm pressure bandaging is an effective means of restricting the lymphatic flow of toxins after envenomation, provided the bandage is applied within the defined pressure range. Strict limb immobilisation is necessary to minimise lymphatic flow, and walking after upper or lower limb envenomation will inevitably result in systemic envenomation despite first-aid measures.

Adult↗
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There are days ... and moons. Self-poisoning is not lunacy.

OBJECTIVE: To determine whether there are significant circadian, weekly or lunar variations in self-poisoning presentations and whether patients' names or dates of birth have an influence on the likelihood of self-poisoning by analysing biorhythms, numerology and star sign. SETTING: Hunter Valley, Australia. SUBJECTS: Consecutive adult patients admitted with self-poisoning between January 1987 and June 1993. RESULTS: There were 2215 patients admitted. There was a marked circadian variation. Over 6% of all admissions occurred in each of the hours between 6 p.m. and 1 a.m. compared with less than 2% per hour between 5 a.m. and 9 a.m. This pattern was not different for patients with a diagnosis of depression. Numerology, biorhythms and star signs had no significant correlations with self-poisoning, nor was there a significant weekly or yearly variation in presentations. There was a small but statistically significant sex difference in presentations analysed by lunar phases. At the new moon 60% of self-poisonings were in women, compared with 45% when the moon was full. The odds ratios (OR) for women to be admitted at full moon and at new moon were 1.27 (95% confidence interval [CI], 0.92-1.66; P value not significant) and 0.73 (95% CI, 0.57-0.92; P = 0.009) respectively. The mean illumination of the moon at the time of overdose was 50.63% +/- 0.91% for men, compared with 47.45% +/- 0.85% for women (P = 0.014). CONCLUSION: The circadian cycle (but not weekly, yearly or mystical cycles) should be taken into account when determining staffing levels for poison information and casualty services. The full moon is protective for women.

Adult↗