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W D Pope

Publications and source records attributed to W D Pope.

9 recordsLinked to original sources
PubMed1992

The Canadian four-centre study of anaesthetic outcomes: I. Description of methods and populations.

The objectives of this study were first to develop and institute a methodology for the study of anaesthetic outcome for parallel use in four teaching hospitals in Canada and second, to compare rates of morbidity and mortality associated with anaesthesia between the four centres. The basic design of the study was occurrence screening with anaesthetists entering data on patient demographics, anaesthetic and surgical factors. Research nurses reviewed anaesthetic records and hospital charts and interviewed patients postoperatively. Data on 37,665 anaesthetics were collected during 1988-89 in the four teaching centres. There were major differences found across the hospitals, particularly with regard to volume, patient case-mix, anaesthetic drugs and monitoring used. The use of parallel training, repeated consultations and use of rounds and inservices contributed to the reliability and validity of the data collection. We conclude that outcome surveillance can be instituted in different hospital Departments of Anaesthesia with sufficient confidence to form the basis of comparison of anaesthetic outcome.

Anesthesia↗
PubMed1992

The Canadian four-centre study of anaesthetic outcomes: II. Can outcomes be used to assess the quality of anaesthesia care?

Since anaesthesia, unlike medical or surgical specialties, does not constitute treatment, this study sought to determine if methods used to assess medical or surgical outcomes (that is the determination of adverse outcome) are applicable to anaesthesia. Anaesthetists collected information on patient, surgical and anaesthetic factors while data on recovery room and postoperative events were evaluated by research nurses. Data on 27,184 inpatients were collected and the analysis of outcomes determined for the intraoperative, post-anaesthetic care unit and postoperative time periods. Logistic regression was used to control for differences in patient populations across the four hospitals. In addition, a random selection of 115 major events was classified by a panel of anaesthetists into anaesthesia, surgical and patient-disease contributions. Across the three time periods, large variations in minor outcomes were found across the four hospitals; these variations ranged from two- to five-fold after case-mix adjustment (age, physical status, sex, emergency versus elective and length of anaesthesia). The rates of major events and deaths were similar across three hospitals; one hospital had a lower mortality rate (P less than 0.001) but had a higher rate of all major events (P less than 0.0001). Of major events assessed by physician panels, 18.3% had some anaesthetic involvement and no deaths were attributable partially or wholly to anaesthesia. Possible reasons to account for these variations in outcome include compliance in recording events, inadequate case-mix adjustment, differences in interpretation of the variables (despite guidelines) and institutional differences in monitoring, charting and observation protocols. The authors conclude that measuring quality of care in anaesthesia by comparing major outcomes is unsatisfactory since the contribution of anaesthesia to perioperative outcomes is uncertain and that variations may be explained by institutional differences which are beyond the control of the anaesthetist. It is suggested that minor adverse events, particularly those of concern to the patient, should be the next focus for quality improvement in anaesthesia.

Anesthesia↗
PubMed1992

The Canadian four-centre study of anaesthetic outcomes: III. Are anaesthetic complications predictable in day surgical practice?

To understand better the factors important to the safety of anaesthesia provided for day surgical procedures, we analyzed the intraoperative and immediate postoperative course of patients at four Canadian teaching hospitals' day treatment centres. After excluding those who received only monitored anaesthesia care, there were 6,914 adult (non-obstetrical) patients seen over a twelve-month period in 1988-89. The rate of adverse outcome consequent to their care was identified by a comprehensive surveillance system which included review of anaesthetic records (four hospitals) and follow-up telephone calls (two hospitals). The relationship between adverse events and preoperative factors was determined by using a multiple logistic regression analysis that included age, sex, duration of the procedure and the hospital care. There were no deaths during the study period and major morbid events were infrequent. Patient preoperative disease was predictive of some intraoperative events relating to the same organ system, but not to events in the PACU. Some unexpected relationships emerged including preoperative hypertension being related to a greater risk of difficult intubation, and neurological disease to perioperative cardiac abnormalities. Patients judged obese, or inadequately fasted, were found to experience a greater rate of recovery problems as well as discomfort. While the low response rate (36%) to the telephone interviews created a sampling bias, the high rate of patient dissatisfaction among those reached is disconcerting. We conclude that day surgical patients with preoperative medical conditions, even when optimally managed, are at higher risk for adverse events in the perioperative period.

Adult↗
PubMed1986

Fetal risk of anesthesia and surgery during pregnancy.

In an attempt to define the risk to the fetus associated with anesthesia and surgery during pregnancy, a study was performed using health insurance data from the province of Manitoba (1971 to 1978). Each of the 2,565 women undergoing incidental surgery during pregnancy (Group A) was paired with a pregnant female not undergoing surgery (Group B) by maternal age and area of residence. Both groups were linked to a separately maintained provincial congenital-anomalies registry to ascertain the frequency of anomalies. There was no significant difference in the rate of congenital anomalies between the two groups, implying no strong teratogenic effect. However, there was an increased risk of spontaneous abortion in those undergoing surgery with general anesthesia in the first or second trimester, most notably after gynecologic procedures (estimated risk ratio = 2.00), but also following procedures anatomically remote from the conceptus (estimated risk ratio = 1.54). While it is concluded that surgery with general anesthesia is associated with a higher incidence of abortion, it is conjectural at present which factor(s) account for the observed increase in fetal risk.

Abortion, Spontaneous↗
PubMed1978

Pressure enhancement of the depressant effect of halothane on cilial beat.

In order to test the applicability of the critical volume hypothesis of anaesthetic action to the side effects of anaesthesia, we have studied the pressure-anaesthetic interactions on cilial beat. The swimming speed of Tetrahymena pyriformis was determined at one and 137 atmospheres with 0 to 4 per cent halothane. The pressure and anaesthetic effects were synergistic with the halothane dose-response curve being shifted to the left and increased in slope at the high pressure, although high pressure alone had no significant effect. These results are contrary to the predictions of the critical volume hypothesis and appear to demarcate the narcotic effect of anaesthetics from the type of molecular interaction which is concerned in the effect on cilial beat.

Cilia↗
PubMed1978

Fetotoxicity in rats following chronic exposure to halothane, nitrous oxide, or methoxyflurane.

An animal model was used to investigate the comparative fetal toxicities of three inhalational anesthetics. Pregnant Sprague-Dawley rats were exposed for eight hours a day throughout the 21 days of gestation to graded concentrations of halothane (0.16-0.32 per cent), or nitrous oxide (1-50 per cent), or a nitrous oxide (10 per cent) and halothane (0.16 per cent) mixture, or methoxyflurane (0.01-0.08 per cent). High subanesthetic concentrations of all the inhalational anesthetics could cause fetal growth retardation (e.g., 3-21 per cent decreases in normal fetal weights), but this was unaccompanied by significant fetal loss (overall rate: 4.8 +/- 1.2 per cent, mean +/- SE, in anesthetic groups) or any evidence of skeletal or gross abnormalities related to treatment. It is concluded that these rodent studies do not implicate any specific inhalational anesthetic agent in fetal toxicity, and that the effects of additional factors, such as stress, must be considered.

Animals↗
PubMed1975

Lack of teratogenic dangers with halothane.

Chronic exposure of pregnant Sprague Dawley rats to a range of halothane concentrations from 50-3200 p.p.m. for 8 hours a day on days 8-12 of gestation failed to demonstrate significant teratogenicity in terms of foetal loss, growth, or skeletal abnormalities. Exposure to 1600 p.p.m. showed significant changes only in foetal weights, which were slightly decreased.

Abnormalities, Drug-Induced↗