Biomedical subjects

K L Ales

Publications and source records attributed to K L Ales.

25 records · Page 2Linked to original sources

PubMed1989

Postoperative renal dysfunction can be predicted.

The two prior hypotheses of the study were that, among a high risk population of patients who were hypertensive, who had diabetes and who underwent elective general surgical treatment, the duration of intraoperative hypotension and hypertension (greater than 20 millimeters of mercury above or below the preoperative base line) and intraoperative administration of less than 300 milliliters per hour of saline solution containing fluids would identify patients at higher risk for postoperative renal dysfunction. Among those who had an intraoperative mean arterial pressure (MAP) that fell more than 20 millimeters of mercury below the base line, 15 per cent of those with fall of MAP lasting for greater than or equal to 60 minutes had postoperative renal dysfunction, whereas those with drops in pressure lasting for less than 60 minutes did not sustain increased postoperative renal dysfunction. Patients who had intraoperative MAP rise to greater than 20 millimeters of mercury above the preoperative base line value for greater than 30 minutes also had twice the rate of postoperative renal dysfunction. Fifteen per cent of the patients who received less than 300 milliliters per hour of isotonic saline-like fluids had postoperative renal dysfunction, significantly more than the 8 per cent of those who received greater than or equal to 300 milliliters per hour. Two intraoperative events also significantly increased postoperative renal dysfunction rates: cardiac arrest and the drainage of massive ascites. Patients with decompensated congestive heart failure at admission to the hospital had significantly increased postoperative renal dysfunction; these patients and probably should not undergo an operation unless it is an emergency. All of the patients, regardless of the magnitude of the operation and of its projected length or type of anesthesia, should be given greater than 300 milliliters per hour of isotonic saline-like solutions.

Aged↗

PubMed1988

Development and validation of a multivariate predictor of mortality in very low birth weight.

Accurate prognosis is critical to the design of all prospective research aimed at improving survival. Predictions based on birth weight, gestational age, or any other single variable, fail to take into account the potentially important contribution of other factors. In order to develop a practical and accurate multivariate model, we studied all singleton pregnancies resulting in viable liveborn infants who weighed less than or equal to 1500 g at birth during 1984 and 1985 at the New York Hospital-Cornell Medical Center. When gestational age, birth weight, and/or crown-heel length were considered, no maternal characteristics were significant predictors of mortality. The model with the maximal predictive accuracy (84.5%) used birth weight and 5-minute Apgar score to calculate a probability of mortality. This prognostic model was then validated in a separate cohort of singletons born in 1986. We conclude that clinical trials should require stratification before randomization, using the calculated probability of mortality, rather than birth weight or gestational age alone. Given the ability of models, such as the one presented here, to generate reasonable estimates of mortality, this information might also be used in the clinical setting to assist parents and physicians in individualized decision-making processes for a given infant.

Adult↗

PubMed1987

Hypocalciuria in preeclampsia.

We studied 40 women in the third trimester of pregnancy to determine whether alterations in serum calcium levels or in urinary calcium excretion would distinguish patients with preeclampsia from normal pregnant women or women with other forms of gestational hypertension. Our population included 10 normal pregnant women, 5 pregnant women with transient hypertension, 6 with chronic hypertension, 7 with chronic hypertension and superimposed preeclampsia, and 12 with preeclampsia. The serum levels of ionized calcium, phosphate, and 1,25-dihydroxyvitamin D were not different among the various groups. In contrast, the mean (+/- SD) 24-hour urinary calcium excretion in the patients with preeclampsia or hypertension with superimposed preeclampsia was significantly lower (42 +/- 29 and 78 +/- 49 mg) than that in normal pregnant women (313 +/- 140 mg per 24 hours), women with transient hypertension (248 +/- 139 mg per 24 hours), or women with chronic hypertension (223 +/- 41 mg per 24 hours) (P less than 0.0001). The hypocalciuria in the women with preeclampsia was associated with a decreased fractional excretion of calcium. Although the mean creatinine clearance was reduced in the women with preeclampsia, the range of values overlapped with those in the other groups. In contrast, we observed little or no overlap with respect to calcium excretion. We conclude that preeclampsia is associated with hypocalciuria due to increased tubular reabsorption of calcium. Measurement of calcium excretion may be useful in distinguishing preeclampsia from other forms of gestational hypertension.

Adult↗

PubMed1987

A new method of classifying prognostic comorbidity in longitudinal studies: development and validation.

The objective of this study was to develop a prospectively applicable method for classifying comorbid conditions which might alter the risk of mortality for use in longitudinal studies. A weighted index that takes into account the number and the seriousness of comorbid disease was developed in a cohort of 559 medical patients. The 1-yr mortality rates for the different scores were: "0", 12% (181); "1-2", 26% (225); "3-4", 52% (71); and "greater than or equal to 5", 85% (82). The index was tested for its ability to predict risk of death from comorbid disease in the second cohort of 685 patients during a 10-yr follow-up. The percent of patients who died of comorbid disease for the different scores were: "0", 8% (588); "1", 25% (54); "2", 48% (25); "greater than or equal to 3", 59% (18). With each increased level of the comorbidity index, there were stepwise increases in the cumulative mortality attributable to comorbid disease (log rank chi 2 = 165; p less than 0.0001). In this longer follow-up, age was also a predictor of mortality (p less than 0.001). The new index performed similarly to a previous system devised by Kaplan and Feinstein. The method of classifying comorbidity provides a simple, readily applicable and valid method of estimating risk of death from comorbid disease for use in longitudinal studies. Further work in larger populations is still required to refine the approach because the number of patients with any given condition in this study was relatively small.

Actuarial Analysis↗

PubMed1987

In search of the true inception cohort.

Prognostic studies hinge on the assembly of a proper inception cohort. The stepwise assembly of a "true" inception cohort of hypertension complicating pregnancy is reported. Standard assembly procedures would have resulted in the preferential reporting of the severest cases of the prognostically worst categories of disease. The less severe cases would have been missed. Prognostic studies should utilize and report a method for assessing potential missed cases, such as a random selection of records for independent review.

Data Collection↗

PubMed1987

Prognosis of hypertension first documented during labor.

In order to assess the prognosis of hypertension first documented during labor, an inception cohort of all women with hypertension complicating pregnancy was assembled. In this cohort, even extreme elevations of blood pressure, regardless of the degree of proteinuria, were not associated with either maternal or fetal adverse outcomes. Therefore, some degree of hypertension during labor may be physiologic. Matched pairs analysis demonstrated that intravenous (IV) magnesium sulfate, administered to prevent seizures, was associated with an excess number of primary cesarean sections. Given the excellent prognoses in patients with good antepartum care in whom hypertension is first documented during labor, the need for any preventive measures, or for antihypertensive or anticonvulsant treatment, should be reconsidered.

Blood Pressure↗

PubMed1987

Why predictive indexes perform less well in validation studies. Is it magic or methods?

When prognostic indexes have been tested in a second population, they have often performed less well. Since this is believed to be inevitable, methodologic differences that may explain the discrepancies have been overlooked. Data from a prospective study of 232 patients undergoing noncardiac surgery were used to examine the effect of methodologic differences in assembly of population, postoperative surveillance, and the criteria for cardiac complications on the performance of Goldman's cardiac risk index. Our prospective population was used to simulate the methods used in Goldman's study and in three other studies using the risk index to demonstrate the potential impact of differences in population, surveillance, and outcome criteria for cardiac complications. If Goldman's detection and outcome criteria were employed and only the eligibility criteria used for assembly of the populations differed, the overall complication rates would be between 5.2% and 6.9%; and the complication rates for the different Goldman classes were similar. When both different detection strategies and different outcome criteria were used, however, important discrepancies in cardiac complication rates emerged. For example, complication rates in class 2 varied from 2% to 23%. In conclusion, important discrepancies in performance of prognostic indexes may arise from differences in surveillance strategies and definitions of outcome. With sufficient attention to methodologic consistency, the performance of predictive indexes may not inevitably deteriorate in subsequent studies.

Adult↗