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Biomedical subjects

P Dolan

Publications and source records attributed to P Dolan.

116 records · Page 7Linked to original sources
PubMedDate not supplied

Time preference, duration and health state valuations.

There is increasing interest in health status measurement and the relative weights that people attach to different states of health and illness. One important issue which has been raised is the effect that the time spent in a health state may have on the way that state is perceived. Previous studies have suggested that the worse a state is, the more intolerable it becomes as it lasts longer. However, for most of these studies, it is impossible to determine how much of what was observed is attributable to the time spent in the state and how much is attributable to when it was occurring. This paper reports on a pilot study designed to test the feasibility of using the Time Trade-Off (TTO) method to isolate the effect of pure time preference from the effect of duration per se. Interviews were conducted with 39 members of the general population who were asked to rate 5 health states for durations of one month, one year and ten years. In aggregate, rates of time preference were very close to zero which suggests that the implicit assumption of the TTO method that there is no discounting may be a valid one. However, that more respondents had negative (rather than positive) rates, casts some doubt on the axions of discounted utility theory. In addition, implied valuations for states lasting for short periods were often counter-intuitive which questions the feasibility of using the TTO method to measure preferences for temporary health states.

Adult↗
PubMedDate not supplied

Chemoprotective effects of two dithiolthiones and of butylhydroxyanisole against carbon tetrachloride and acetaminophen toxicity.

Administration of tert-butyl-4-hydroxyanisole or of two dithiolthiones to female CD-1 mice protected against the acute toxic effects of two hepatotoxic agents, acetaminophen and carbon tetrachloride. Reduced mortality of mice was observed following pretreatment with tert-butyl-4-hydroxyanisole or dithiolthiones. Pretreatment reduced or prevented hepatic glutathione depletion produced by these two hepatotoxic agents. Liver damage, i.e., as determined by serum transaminase and sorbitol dehydrogenase activities, was less after pretreatment with tert-butyl-4-hydroxyanisole or dithiolthiones. Administration of dithiolthiones resulted in increased (from four- to over six-fold) activities of liver glutathione-S-transferases.

Acetaminophen↗
PubMedDate not supplied

The relationship between EMG activity and extensor moment generation in the erector spinae muscles during bending and lifting activities.

The relationship between EMG activity and extensor moment generation in the erector spinae muscles was investigated under isometric and concentric conditions. The full-wave rectified and averaged EMG signal was recorded from skin-surface electrodes located over the belly of the erector spinae at the levels of T10 and L3, and compared with measurements of extensor moment. The effects of muscle length and contraction velocity were studied by measuring the overall curvature (theta) and rate of change of curvature (d theta/dt) of the lumbar spine in the sagittal plane, using the '3-Space Isotrak' system. Isometric contractions were investigated with the subjects pulling up on a load cell attached to the floor. Hand height was varied to produce different amounts of lumbar flexion, as indicated by changes in lumbar curvature. The extensor moment was found to be linearly related to EMG activity, and the 'gradient' and 'intercept' of the relationship were themselves dependent upon the lumbar curvature at the time of testing. Concentric contractions were investigated with the subjects extending from a seated toe-touching position, at various speeds, while the torque exerted on the arm of a Cybex dynamometer was continuously measured. Under these conditions the EMG signal (E) was higher than the isometric signal (E0) associated with the same torque. E and E0 were related as follows: E0 = E/(1 + A d theta/dt), where A = 0.0014 exp (0.045P) and P = percentage lumbar flexion. This equation was used to correct the EMG data for the effect of contraction velocity. The corrected data were then used, in conjunction with the results of the isometric calibrations, to calculate the extensor moment generated by the erector spinae muscles during bending and lifting activities. The extensor moment can itself be used to calculate the compressive force acting on the lumbar spine.

Adult↗
PubMedDate not supplied

Whose preferences count?

An important consideration when choosing how to allocate health care resources is the improvements in patients' health-related quality of life (HRQoL) that alternative allocations generate. There is considerable debate about whose preferences should be used when measuring and valuing HRQoL. This debate has usually been in terms of whether the values of patients or the general public are the most appropriate. It is argued in this paper that this is a false dichotomy that does not facilitate understanding of empirical evidence. Nor, more importantly, does it address one of the most important issues in the debate about whose preferences count, that is, whether the fact that many people adapt to poor health states should be taken into account when ascribing values to those states. A conceptual framework is developed to facilitate a more fruitful discussion of the issues relating to the question of whose preferences should count.

Attitude to Health↗
PubMedDate not supplied

Use of colchicine to treat severe constipation in developmentally disabled patients.

BACKGROUND: Patients with severe developmental disabilities often have concurrent decreased neuromuscular tone of the gastrointestinal tract, which can lead to a weak gag reflex, esophageal reflux, aspiration, and severe intractable constipation. High doses of multiple laxatives are frequently needed to maintain bowel motility in these patients. Colchicine, a natural alkaloid that is primarily used for the treatment of acute attacks of gout, causes an increase in gastrointestinal motility by neurogenic stimulation. The purpose of this study was to determine whether daily colchicine administration can improve bowel function and reduce laxative use in profoundly disabled patients with severe, intractable constipation who currently require large doses of multiple laxatives. METHODS: Twelve developmentally disabled patients who required three or more different laxatives to manage their chronic constipation were selected to participate in a double-blind, crossover study. Eleven patients who completed the study received placebo treatment for 8 weeks and colchicine treatment for 8 weeks. The total number of bowel movements and the total number of laxatives used during each of the two 8-week periods were compared. RESULTS: Eight of 11 patients experienced an improved bowel pattern while on colchicine compared with placebo, as defined by an increase in total number of bowel movements or a decrease in total number of rectal laxatives used. No clinically important complications were related to use of colchicine. CONCLUSIONS: Colchicine appears to be a valuable adjunct in the management of severe intractable constipation. Larger, long-term studies are needed to confirm these preliminary results.

Adult↗
PubMedDate not supplied

Pulse oximetry: evaluation of accuracy during outpatient general anesthesia for oral surgery.

Pulse oximetry has been shown to be accurate under steady state conditions. In this study, the accuracy of four pulse oximeters are evaluated and compared during outpatient general anesthesia for third molar extractions. The oximeters evaluated are the Nellcor N-100, the Ohmeda 3700, the Novametrix model 500, and the Bird 4400 portable pulse oximeter.Ultralight general anesthesia for oral surgery presents a unique challenge for respiratory monitoring in that patients are often not intubated and commonly experience periods of hyper- and hypoventilation. Airway obstruction, apnea, and laryngospasm may occur easily and patients often vocalize and move during surgery. Because hypoxemia is the primary cause of morbidity and mortality during anesthesia, an accurate, continuous, and noninvasive monitor of oxygenation is critical to risk management.Twenty ASA class I and II patients underwent outpatient general anesthesia for third molar removal using nitrous oxide-oxygen, midazolam, fentanyl, and methohexital. Arterial blood samples were obtained at five-minute intervals during anesthesia, as well as any time a desaturation of >5% occurred, for measurement of arterial SaO(2) with an IL282 CO-Oximeter. These values were compared with simultaneously recorded saturations observed for each pulse oximeter. A total of 122 arterial samples were obtained over a range of PaO(2) from 52-323 mm Hg and observed saturations of 70-100%.The Bird 4400 portable pulse oximeter proved to be the most accurate and reliably predicted arterial saturation under these conditions (y = 1.03x - 2.8, r = 0.85). The Novametrix model 500 pulse oximeter also demonstrated a high degree of accuracy by linear regression analysis, but displayed the lowest correlation coefficient (spread of data points) overall (y = 0.97x + 2.8, r = 0.80.) The Nellcor N-100 pulse oximeter also proved to be highly accurate. (y = 1.05x - 4.1, r = 0.84.) In contrast, regression analysis of the observed saturations obtained with the Ohmeda 3700 pulse oximeter revealed that this unit significantly underestimated arterial saturation (y = 1.20x - 19.6, r = 0.83.)This study demonstrates that despite the rigorous conditions imposed by outpatient general anesthesia for oral surgery, three of the pulse oximeters tested were linearly accurate in predicting arterial oxyhemoglobin saturation over the range of 70-100%. The Ohmeda 3700 was found to significantly underestimate arterial saturation.

Ambulatory Care↗