Biomedical subjects

P C Duke

Publications and source records attributed to P C Duke.

5 recordsLinked to original sources

PubMed1991

The automated interview versus the personal interview. Do patient responses to preoperative health questions differ?

Laboratory testing of presurgical patients has been shown to be excessive, thereby increasing costs, reducing resources for other health care uses, and increasing risks to both patients and physicians. As one step toward reducing the number of unnecessary preoperative tests ordered, we used an automated method to aid preoperative assessment of 239 patients in Chicago and in Winnipeg. The "HealthQuiz," a small hand-held device containing a computer chip and video screen, uses a decision tree to ask a minimum of 60 health-related questions (the patient's response to certain questions determines the number of questions presented). The device then generates a summary printout of patient answers, the health areas needing further attention, and the laboratory tests most likely to uncover clinically important abnormalities in that patient. HealthQuiz responses are intended to aid the physician and not to replace the personal interview. As an aid, the automated interview highlights possible problem areas for in-depth pursuit by the physician. The need for nonselective batteries of tests is eliminated because recommendations for tests are based on specific elements of a patient's history. To be effective, responses to the HealthQuiz should be the same as responses to similar questions asked by a physician. We tested that premise in this study. Patient's answers to the HealthQuiz were compared with their responses to a randomly selected set of the same questions in a personal interview. Ninety-seven percent of the response pairs were identical, and most of the 3% that differed involved changes from "not sure" replies to the HealthQuiz. Laboratory tests suggested by responses to the two methods of questioning did not differ.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1979

The effect of morphine on human neuromuscular transmission.

By utilizing high frequency nerve stimulation, we observed the effects of morphine sulphate, 0.5 mg.kg-1 on human neuromuscular transmission. Tetanic fade at 50, 100 and 200 hz did not change during the one hour period after infusion of morphine. Post-tetanic depression (PTD) of single twitch response increased progressively with time over the one-hour study period. This was most marked with the 100 and 200 hz tetanic frequencies. In contrast, control subjects displayed either no change, or a slight increase (post-tetanic facilitation; PTF), over a similar one-hour test period. We believe these results are best explained by a presynaptic action of morphine, whereby intraterminal mobilization of acetylcholine is impaired by the opiate narcotic drug.

Acetylcholine↗

PubMed1977

Halothane depresses baroreflex control of heart rate in man.

Baroreflex control of heart rate was determined during three awake control situations and during two depths of halothane anesthesia in man. Baroreflex function was quantiated by calculating the pressor test slope from the R-R interval change on the ECG produced by a pharmacologically induced pressor response. During the three awake control situations the subjects breathed room air or 100 per cent O2 spontaneously or 100 per cent O2 with ventilation controlled. Mean (+/- SD) slopes obtained were 15.1 +/- 4.5, 15.6 +/- 6.8 and 18.4 +/- 9.9, respectively. No significant difference in baroreflex function slope was observed. During light halothane anesthesia (0.7 per cent endtidal) baroreflex function was significantly depressed (mean slope = 2.5 +/- 1.5), and it was abolished at 1.1 per cent end-tidal halothane (mean slope = 0.03 +/- 0.04). It is concluded that halothane anesthesia produces depression of baroreflex control of heart rate in man.

Adult↗

PubMed1976

The effects of age on baroreceptor reflex function in man.

The relationship of age to baroreceptor reflex activity was determined in 35 healthy volunteers ranging in age from 19 to 65 years. Intra-arterial catheters were placed and blood pressure and pulse rate responses of each subject were observed during a Valsalva maneuver (31 subjects) and during the Pressor Test (33 subjects). The Valsalva maneuver consisted of a forced expiration sufficient to raise a column of mercury 40 torr for 10 seconds. This resulted in a reduction in pulse pressure (Baroreceptor stimulus) during the maneuver followed by a transient overshoot in diatolic pressure (response) following its termination. In comparison to younger subjects, older subjects had a greater reduction in pulse pressure but similar overshoot in diastolic pressure. The pressor test consisted of observing the effect of increasing systolic blood pressure (stimulus) on pulse duration (response) following the intravenous administration of phynylephrine. By relating each systolic pressure to the immediately succeeding R-R interval, a linear relationship was found. Its slope expressed in milliseconds of R-R interval change per torr increase in systolic pressure is an index of baroreflex function. Older subjects have less cardiac slowing compared to younger subjects and a hyperbolic relationship exists between age and slope (r = 0.84, p less than 0.05). These tests indicate that baroreceptor reflex function decreases with aging.

Adult↗

PubMed1975

The myocardial effects of pancuronium.

The effect of pancuronium on myocardial contractility was studied in three different animal preparations. Pancuronium produced no change in isometric contraction of rabbit atrial or cat papillary muscle but displaced the acetylcholine dose-response curve to the right in the papillary muscle preparations, verifying a muscarinic blocking effect of this drug. In atropinized dogs in vivo pancuronium produced no significant change in the cardiovascular parameters studied. These studies show that pancuronium exerts its cardiovascular effects primarily by blocking muscarinic receptors in the heart.

Acetylcholine↗