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Biomedical subjects

K L Ales

Publications and source records attributed to K L Ales.

At least 19 recordsLinked to original sources

Using faculty consensus to develop and implement a medical ethics course.

This report describes the development and implementation of a new required course in medical ethics for second-year medical students at the Cornell University Medical College, 1988-89 and 1989-90. The course was specifically designed to teach students who had not yet started their clinical clerkships to think critically and systematically about ethical issues faced by practicing physicians. The goals, structure, and content of the course were developed using an innovative technique, a planning model involving faculty consensus. The faculty members found the planning sessions intellectually challenging and enjoyable, and reported that the sessions added greatly to their teaching of the course. The students' evaluations over the first two years of the course (with 188 of the 201 students--94%--responding) documented the students' satisfaction with the content and the structure of the course, and their belief that the course had achieved its goals. The authors conclude that the faculty's participation in the planning process was crucial to the success of the course.

Consensus

Risk for postoperative congestive heart failure.

To identify predictors of postoperative congestive heart failure (CHF), a high-risk population, mainly hypertensive and diabetic patients undergoing elective general operations, was studied. Of the 254 patients, 6 per cent had postoperative CHF. Among patients with preoperative cardiac disease (that is, previous myocardial infarction, valvular disease or CHF), 17 per cent had postoperative CHF; in contrast with less than 1 per cent of those without cardiac disease (p less than 0.001). Patients with diabetes were also at high risk (12 versus 2 per cent, p less than 0.005), particularly those with cardiac disease. Patients who had equal to or greater than 40 millimeters of mercury increases or decreases intraoperatively in mean arterial pressure in relation to preoperative baseline had increased postoperative failure rates (p less than 0.02). Of note, postoperative failure rates were highest among patients with less than 500 milliliters per hour of net intake (input and output) (p less than 0.03). Risk for postoperative CHF was restricted to patients with preoperative symptomatic cardiac disease and was especially high if patients also had diabetes. Intraoperative fluctuations in mean arterial pressure increased the probability of postoperative failure, while the intraoperative administration of higher net volumes of fluid was associated with decreased risk.

Aged

Longitudinal study of the renin-angiotensin-aldosterone system in hypertensive pregnant women: deviations related to the development of superimposed preeclampsia.

A prospective longitudinal study of 25 pregnant women (30 pregnancies) with chronic hypertension, a group prone to development of preeclampsia, was conducted to explore the relationship between the renin-angiotensin-aldosterone system and the development of superimposed preeclampsia. In women with chronic hypertension in whom preeclampsia did not develop (17 pregnancies), blood pressure decreased and the renin-angiotensin-aldosterone system was stimulated, beginning in the first trimester and continuing throughout pregnancy as found previously in normotensive pregnant women (n = 58). Plasma estradiol and progesterone levels also increased progressively. In women with chronic hypertension in whom preeclampsia developed (13 pregnancies), blood pressure decreased and the renin-angiotensin-aldosterone system was stimulated in the first trimester as in the other groups. However, later in pregnancy significant differences were observed. Blood pressure began to rise in the second trimester. Initially the renin-angiotensin-aldosterone system remained stimulated, but in the early third trimester, when preeclampsia was diagnosed, plasma renin activity and urine aldosterone excretion decreased, and atrial natriuretic factor increased. These data provide information that may be useful in the recognition of superimposed preeclampsia, and in the investigation of its pathogenesis.

Adult

The clinical significance of predictions based on screening second trimester mean arterial pressure: adverse maternal [corrected] and infant outcomes.

The design of a trial of primary prevention of hypertension in pregnancy rests on both the ability to identify women who are at risk and the definition of a clinically important outcome. The risk of developing antepartum hypertension can now be assessed nonivasively by the midpoint of pregnancy. However, maternal hypertension is not always associated with a clinically important adverse outcome for either mother or infant. The purpose of this study was to prospectively assess whether increasing risk of antepartum hypertension is associated with increasing rates of clinically important maternal and/or infant morbidity. We assembled a prospective cohort of 720 women with singleton pregnancies. The proportion of pregnancies complicated by both antepartum hypertension and maternal and/or infant morbidity increased significantly between low, moderate, and high risk groups (0.2, 6 and 58.8%, respectively, p less than 0.0001). We conclude that a trial of primary prevention of hypertension in pregnancy should include a measure of significant morbidity in mother and infant.

Cohort Studies

Preoperative characteristics predicting intraoperative hypotension and hypertension among hypertensives and diabetics undergoing noncardiac surgery.

We prospectively studied patients with hypertension and diabetes undergoing elective noncardiac surgery with general anesthesia to test the hypothesis that patients at high risk for prognostically significant intraoperative hemodynamic instability could be identified by their preoperative characteristics. Specifically we hypothesized that patients with a low functional capacity, decreased plasma volume, or significant cardiac comorbidity would be at high risk for intraoperative hypotension and those with a history of severe hypertension would be at risk for intraoperative hypertension. Patients who had a preoperative mean arterial pressure (MAP) greater than or equal to 110, a walking distance of less than 400 m, or a plasma volume less than 3000 cc were at increased risk of intraoperative hypotension (i.e., more than 1 hour of greater than or equal to 20 mmHg decreases in the MAP). Hypotension was also more common among patients having intra-abdominal or vascular surgery, and among those who had operations longer than 2 hours. Patients older than 70 years or with a decreased plasma volume were at increased risk of having more than 15 minutes of intraoperative elevations of greater than or equal to 20 mmHg over the preoperative MAP in combination with intraoperative hypotension; this was also more common when surgery lasted more than 2 hours. Patients who had intraoperative hypotension tended to have an immediate decrease in MAP at the onset of anesthesia and were often purposefully maintained at MAPs less than their usual level during surgery with fentanyl and neuromuscular blocking agents. Patients who had intraoperative hyper/hypotension tended to have repeated elevations in MAP above their preoperative levels during the course of surgery, and such elevations precipitated interventions with neuromuscular blocking agents and/or fentanyl. Neither pattern was more common among patients who developed net intraoperative negative fluid balances. Both hypotension and hyper/hypotension were associated with increased renal and cardiac complications after operation. Patients with cardiac disease, especially diabetics, and those with negative fluid balances also had increased complications. Preoperative characteristics influence the susceptibility to intraoperative hypotension and hypertension, which are related to postoperative complications.

Aged

Intraoperative blood pressure. What patterns identify patients at risk for postoperative complications?

While monitoring blood pressure is a routine part of intraoperative management, several methods have been proposed to characterize intraoperative hemodynamic patterns as predictors of postoperative complications. In this prospective study of a high-risk population of hypertensive and diabetic patients undergoing elective noncardiac surgery, one objective was to compare different approaches to the assessment of intraoperative hemodynamic patterns to identify those patterns most likely to be associated with postoperative complications. Twenty-one per cent of the 254 patients sustained cardiac or renal complications after operation. Patients with more than 1 hour of greater than or equal to 20-mmHg decreases in mean arterial pressure (MAP) or patients with less than 1 hour of greater than or equal to 20-mmHg decreases and more than 15 minutes of greater than or equal to 20-mmHg increases were at highest risk for postoperative complications. Together these two patterns had a 46% sensitivity rate and a 70% specificity rate in predicting postoperative complications. Using 20% change in intraoperative MAP produced results nearly identical to 20-mmHg changes. When the duration of 20-mmHg changes was accounted for, changes of a greater magnitude (e.g., 40 mmHg) were not significant independent predictors of complications. The use of the mean difference from preoperative MAP was misleading because patients who experienced both high and low MAPs tended to have nearly normal mean MAPs, but high complication rates. The absolute magnitude of intraoperative MAPs, regardless of the preoperative levels, also was evaluated. The overall mean intraoperative MAP was not a significant predictor of complications. Specific intraoperative MAPs (e.g., less than 70 mmHg and more than 120 mmHg) also were evaluated. While neither was a significant predictor, there was a trend for increased complications among patients whose MAPs decreased to less than 70 mmHg. Intraoperative blood pressure should be analyzed in relation to the patient's preoperative blood pressure. Prolonged changes of more than 20 mmHg or 20% in relation to preoperative levels were significantly related to complications.

Blood Pressure

The impact of universal screening for gestational glucose intolerance on outcome of pregnancy.

Universal screening for gestational glucose intolerance has strong support, despite the lack of scientific evidence documenting its benefit. In the early 1980s, practicing obstetricians were split concerning the clinical importance of gestational glucose intolerance, so that some practitioners tested virtually all the patients they treated while others tested none. This historical reality provided concurrent screened and unscreened populations in whom to assess the impact of screening. We studied all 1,307 singleton pregnancies cared for and delivered at the New York Hospital-Cornell University Medical Center during a five month period. Large infants (birth weight greater than or equal to 4,000 grams) were born to 10.5 per cent of the women who were not screened (533) and to 11.2 per cent of the women who were screened (774). The process of screening not only failed to decrease the rate of large infants, but also failed to improve otherwise pregnancy outcomes and was associated with more intensive surveillance during pregnancy and a significantly higher rate of primary cesarean delivery. Given the unexpected concomitants of the screening process, we conclude that recommendations for universal screening for gestational glucose intolerance should be reconsidered.

Adult

Impact of advanced maternal age on the outcome of pregnancy.

We assessed the impact of advanced maternal age on the outcome of pregnancy by studying all 1,328 women who were primarily cared for and delivered at our institution between 14 September 1984 and 12 February 1985. Important peripartum maternal complications were no more frequent in women aged 35 years or more than in women 20 to 34 years old, although operative delivery was significantly more common. Similarly, adverse outcomes of infants were no more frequent. Perinatal mortality tended to be lower. In addition, we noted a trend for fewer infants with congenital anomalies to be born among older women. This trend was related, in part, to the choice to terminate the pregnancy by women with fetuses that had documented chromosomal anomalies. We conclude that advanced maternal age was not associated with an excess of adverse pregnancy outcome and suggest that, with early registration and careful surveillance during pregnancy, women aged 35 years or more can experience excellent pregnancy outcomes.

Abortion, Induced

Should all pregnant women be screened for gestational glucose intolerance?

Although gestational glucose intolerance is associated with the remote development of diabetes mellitus, the risk to the mother during the index pregnancy and the risk to her fetus remain uncertain. Nevertheless, universal screening for gestational glucose intolerance has many strong advocates. The scientific data supporting a universal screening programme--showing that treatment of gestational glucose intolerance does more good than harm--are limited. Until the evidence can be extended beyond that on infant birthweight, a more restrained approach than universal screening may be appropriate.

Birth Weight

The post-operative electrocardiogram and creatine kinase: implications for diagnosis of myocardial infarction after non-cardiac surgery.

The objective of this study was to evaluate different approaches to the diagnosis of post-operative myocardial infarction. A total of 232 patients, mostly hypertensive and/or diabetic patients, who were undergoing elective non-cardiac surgery were evaluated pre-operatively. They were followed serially from the day of operation to discharge or the sixth post-operative day with daily clinical evaluations, electrocardiograms, creatine kinase and creatine kinase isoenzymes. In total 22% (51/232) of the patients had post-operative ECG changes in two or more leads. Only 1% developed new Q waves; most of the changes involved changes in the T or ST segments. Seventy percent of patients who had changes in their electrocardiogram were completely asymptomatic. The highest risk of ECG changes or symptoms occurred on the day of operation and the first post-operative day; evidence of post-operative infarction was infrequent after the second post-operative day. Creatine kinase levels rose an average of 250-300 IU on the first and second post-operative day (also the peak time for post-operative ECG changes), reducing its utility as an adjunct to the diagnosis of post-operative infarctions. Importantly, 52% (12/23) of the patients who had greater than or equal to 5% MB isoenzyme had neither ECG changes nor symptoms; the diagnosis of a myocardial infarction should not be made in these patients. In summary, most patients who experience ischemia or infarction post-operatively are asymptomatic. Symptoms should not be required for the diagnosis of post-operative infarction. Seemingly minor differences in criteria can produce major discrepancies in post-operative myocardial infarction rates (from 1 to 9%). The development of a final set of criteria will require further study but the diagnosis of post-operative infarction should probably be based on ECG changes, their duration and consistency, and the association of a positive MB fraction.

Aged

Changes in functional status during pregnancy.

Changes in self-reported functional status during pregnancy were studied in 100 women. The baseline interview at 20 weeks was used for assessing subsequent change in maximal physical, mental, and emotional function as well as in global function and global sense of health. Although the transition instruments were only tested at three points during pregnancy (30, 35, and 40 weeks), they succeeded in detecting changes. In particular, both maximal physical function and global function tended to deteriorate as pregnancy progressed toward term, although few women considered themselves to be sick. The authors suggest that changes in functional status should be considered an important "outcome" of pregnancy. Patient-specific measures of change in self-reported maximal function might be used in future trials to help assess the impact of interventions on individual patient's maximal function. The timing of the baseline interview and frequency of the transition assessments should depend on the specific clinical problem under study.

Activities of Daily Living

The preoperative and intraoperative hemodynamic predictors of postoperative myocardial infarction or ischemia in patients undergoing noncardiac surgery.

Among hypertensive and diabetic patients undergoing elective noncardiac surgery, preoperative status and intraoperative changes in mean arterial pressure (MAP) were evaluated as predictors of postoperative ischemic complications. Of 254 patients evaluated before operation and monitored during operation, 30 (12%) had postoperative cardiac death, ischemia, or infarction. Twenty-four per cent of patients with a previous myocardial infarction or cardiomegaly had an ischemic postoperative cardiac complication. Only 7% of those without either of these conditions sustained an ischemic complication. No other preoperative characteristics, including the presence of angina, predicted ischemic cardiac risk. Nineteen per cent of patients who had 20 mm Hg or more intraoperative decreases in MAP lasting 60 minutes or more had ischemic cardiac complications. Patients who had more than 20 mm Hg decreases in MAP lasting 5 to 59 minutes and more than 20 mm Hg increases lasting 15 minutes or more also had increased complications (p less than 0.03). Changes in pulse were not independent predictors of complications and the use of the rate-pressure product did not improve prediction based on MAP alone. In conclusion patients with a previous infarction or radiographic cardiomegaly are at high risk for postoperative ischemic complications. Prolonged intraoperative increases or decreases of 20 mm or more in MAP also resulted in a significant increase in these potentially life-threatening surgical complications.

Adult

Early prediction of antepartum hypertension.

We validated a mid-pregnancy screening mean arterial pressure (MAP2) of 85 mmHg or higher as a significant predictor of hypertension in pregnancy. During the 17-month period from October 1984 through February 1986, 730 women, or 16% of all women cared for and delivered at our institution, were screened at or near 20 weeks of amenorrhea. Of the 139 women with a MAP2 of 85 mmHg or higher, 21.6% developed antepartum hypertension, compared with only 0.7% of the 591 women with a MAP2 below 85 mmHg. The screening MAP2 level of 85 mmHg was the optimal cutoff for MAP2 as a screening test. Controlling for the value of the screening MAP2, the only other important predictors of antepartum hypertension were chronic hypertension and diabetes mellitus. Using these three variables, the probability that an individual pregnant woman will develop antepartum hypertension can be assessed with a high degree of accuracy (84.5%) by 20 weeks of amenorrhea. This assessment is noninvasive and simple to use. Three distinct levels of risk have been defined; the moderate- and high-risk groups warrant careful surveillance during pregnancy and may be reasonable groups in which to test preventive interventions.

Adult