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D Biehl

Publications and source records attributed to D Biehl.

14 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↗
PubMed1987

The effect of ketamine anaesthesia on the acidotic fetal lamb.

The following study in pregnant ewes was done to examine the effects of ketamine-oxygen anaesthesia on the fetal lamb made acidotic by partial occlusion of the umbilical cord. Fifteen pregnant ewes were instrumented under general anaesthesia to allow continuous measurement of maternal and fetal mean arterial pressure and pulse rate and for withdrawal of arterial blood samples for blood gas analysis. An occlusion loop was loosely secured around the umbilical cord. Following a recovery period of 48 hours, a tracheostomy was performed on each ewe. After a control period, the umbilical occlusion loop was slowly inflated until fetal pH had decreased to 7.12-7.15. Following inflation the animals were divided into groups A and B. Group A received no anaesthesia. In Group B, the ewes received ketamine 3 mg X kg-1 intravenously and controlled ventilation with FIO2 of 1.0. After ten minutes ketamine 1 mg X kg-1 was given. In both groups radioactive microspheres were injected into the fetus at 0, 5, and 15 minutes. Ketamine anaesthesia in the pregnant ewe abolished the fetal hypertension and bradycardia produced by partial cord occlusion. All fetuses survived the 15 minutes of ketamine anaesthesia and there were no significant changes in arterial blood gases or pH. Blood flows determined by the microsphere method to the brain, heart, and kidneys were not significantly altered by ketamine. We conclude that ketamine-oxygen anaesthesia does not cause further deterioration in the acidotic fetal lamb.

Acidosis↗
PubMed1986

The effect of lidocaine on regional blood flows and cardiac output in the non-stressed and the stressed foetal lamb.

Lidocaine has been used in obstetrical anaesthesia for many years but there are still concerns about possible adverse affects of this drug on the foetus in utero. To examine in greater detail the effects of lidocaine in the foetus, the following two-part study was done. In Part A, seven pregnant ewes were surgically prepared with maternal and foetal arterial and venous catheters. After recovery from surgery lidocaine was infused intravenously, initially into the ewe and then into both ewe and foetus. Blood lidocaine concentrations were monitored and foetal regional blood flows were determined by the radioactive microsphere method. In Part B, 14 ewes were prepared as in Part A with the addition of an inflatable loop around the umbilical cord. During each study the loop was inflated to partially compress the cord and produce foetal acidosis. In all animals this cord compression was maintained for 30 minutes. In seven animals a lidocaine infusion was given, to examine the effect of lidocaine in the acidotic foetus. Organ blood flows were measured and cardiac outputs calculated. The normal foetuses in Part A showed no change in organ blood flow or cardiac output with arterial lidocaine concentrations of 1.5-3.4 mg X ml-1. In the acidotic foetuses, lidocaine concentrations of 1.4-1.5 mg X ml-1 produced a tachycardia and an increase in cerebral blood flow compared to the control acidotic foetuses. There were no other significant changes. We conclude that arterial lidocaine concentrations of less than 3.5 mg X ml-1 do not produce significant alterations in organ blood flow in normal foetal lambs.(ABSTRACT TRUNCATED AT 250 WORDS)

Acidosis↗
PubMed1985

Ovine fetal urine production following maternal intravenous furosemide administration.

The response of the ovine fetus to maternal furosemide administration was studied in six chronically catheterized fetal lamb preparations. These studies indicate that in the chronic sheep model maternally administered diuretics do not augment fetal urine production. Additionally, passage of the drug from the maternal intravascular compartment to the fetal intravascular compartment could not be demonstrated. It is suggested that on the basis of these data, the results of the "Lasix challenge test" should be interpreted with caution when they are used to evaluate human fetal renal function.

Amniotic Fluid↗
PubMed1985

The effects of general anaesthesia on the asphyxiated foetal lamb in utero.

The effects of anaesthetic agents, per se, on the asphyxiated foetus are difficult to quantitate clinically. Anaesthesia is often necessary in foetal distress, however, to effect a rapid delivery. To investigate the effect of general anaesthetic agents commonly used for Caesarean section we administered these agents to 18 chronically prepared pregnant ewes with asphyxiated foetuses in utero. The foetuses were asphyxiated by partial occlusion of the umbilical cord until foetal arterial pH had decreased from 7.30 to a range of 7.08-7.13. The animals were divided into three groups: Group A which received no anaesthesia and thus served as a control, Group B which received thiopentone (3 mg . kg-1) intravenously followed by 50 per cent nitrous oxide and 0.5 per cent halothane in oxygen for 15 minutes, and Group C which received thiopentone (3 mg . kg-1) followed by one per cent halothane in oxygen for 15 minutes. Foetal cerebral, myocardial, and renal blood flows were measured by injection of radioactive microspheres after production of asphyxia and after 5 and 15 minutes of anaesthesia. General anaesthesia in both groups B and C abolished the hypertension and bradycardia produced by foetal asphyxia secondary to umbilical cord occlusion. There were no significant differences between Groups B and C in foetal pH, PCO2, or PO2. Two foetuses in the nitrous oxide group died after ten minutes of anesthesia, but the aetiology of the sudden demise is unclear. We conclude that general anaesthesia abolishes the foetal response to umbilical cord occlusion and does not improve foetal oxygenation or acid-base status.

Anesthesia, General↗
PubMed1981

The effect of foetal acidosis on bupivacaine levels in utero.

Amide local anaesthetics are weak bases with pK's of 7.80 or greater. Therefore, tissue acidosis may result in ionization and "trapping" of the basic local anaesthetics The following study was done in the pregnant ewe to determine if the highly protein-bound local anaesthetic bupivacaine demonstrates ion-trapping in the acidotic foetus. Six pregnant ewes of 135 days gestation were prepared surgically with catheters placed in maternal and foetal femoral arteries an veins. Bupivacaine was infused into the maternal femoral vein to maintain a constant concentration. After two hours of bupivacaine infusion the foetus was made acidotic by an infusion of lactic acid for 45 minutes. Then the acidosis was corrected by an infusion of bicarbonate for an additional 45 minutes. Maternal and foetal bupivacaine levels were measured at 15 minute intervals throughout the experiment. The bupivacaine levels in the foetus and the foetus-maternal ratio increased significantly during the period of foetal acidosis and declined to the control levels when the acidosis was corrected with bicarbonate. We conclude from this study that foetal acidosis results in ion-trapping of bupivacaine to a significant extent, despite protein binding in the maternal blood.

Acidosis↗
PubMed1978

Placental transfer of lidocaine: effects of fetal acidosis.

To investigate whether fetal acidosis increases the placental transfer of lidocaine, resulting in higher fetal blood levels of the drug, lidocaine was infused intravenously into ten pregnant ewes to maintain plasma levels of 2-4 microgram/ml. After maternal-fetal equilibrium was reached, the fetus was made acidotic by infusing lactic acid intravenously. Fetal blood pH decreased from 7.35 to 7.10. With fetal acidemia, fetal blood lidocaine levels increased significantly from 1.60 +/- 0.11 microgram/ml to 2.72 +/- 0.26 microgram/ml. The fetal-maternal lidocaine ratio increased from 0.76 to 1.21. Correction of the acidosis by bicarbonate infusion returned the fetal-maternal ratios to control values. It is concluded that acidosis in the fetus may result in trapping of ionized lidocaine in the fetal circulation and increase the transfer of lidocaine across the placenta.

Acidosis↗
PubMed1977

The direct effects of circulating lidocaine on uterine blood flow and foetal well-being in the pregnant ewe.

We infused lidocaine intravenously into 13 pregnant ewes at a rate sufficient to maintain plasma levels between 2-4 mugm/ml, which are those commonly seen with regional anaesthesia. These levels did not change maternal blood pressure, pulse rate, cardiac output, stroke volume, total peripheral resistance, uterine blood flow or intra-amniotic pressure. Foetal blood pressure and pulse rate remained stable as did both maternal and foetal blood gases and acid-base values.

Animals↗
PubMed1977

Maternal and neonatal effects of methoxyflurane, nitrous oxide and lumbar epidural anaesthesia for Caesarean section.

General anaesthetic techniques continue to be used for Caesarean section despite the possible increased incidence of foetal acidosis and neonatal depression. Two techniques of general anaesthesia (methoxyflurane-oxygen and nitrous oxide-oxygen) and lumbar epidural anaesthesia were compared in 37 patients under-going elective Caesarean section. Apgar scores at birth were similar in all three groups. Neurophysiological testing of the neonates at six hours and twenty-four hours of age revealed a superiority for the methoxyflurane-oxygen and lumbar epidural techniques, although the babies in the epidural group tended to be hypotonic. Cord blood gas analysis showed the babies in the methoxyflurane group to have a higher PaO2 with less metabolic acidosis than the babies from the other two groups. The maternal effects of the three anaesthetic techniques were similar, with only a small rise in serum fluroide levels noted in the methoxyflurane group.

Anesthesia, Epidural↗