Determinants of blood utilization during myocardial revascularization.

Blood transfusion during cardiac surgical procedures has steadily decreased, but little information is available regarding the factors that determine its necessity or amount. To determine the predictors of blood utilization during myocardial revascularization, 441 consecutive patients undergoing primary myocardial revascularization were studied. Forty-four patients (10%) received blood during hospitalization with a mean transfusion of 0.3 +/- 1.4 units per patient. Age, sex, weight, body surface area, preoperative hematocrit, blood volume, and red blood cell volume were examined univariately for trends. All demonstrated a statistically significant trend for both need and amount of transfusion (p less than 0.001). Neither number of grafts nor duration of cardiopulmonary bypass demonstrated statistically significant trends. All univariately significant factors were evaluated by multivariate logistic regression analysis. Red cell volume was the best predictor of the need for transfusion (p less than 0.001), followed by age. No other factors improved predictive capabilities. We conclude that preoperative red cell mass and age are the principal determinants of the need for and quantity of blood transfused during myocardial revascularization. Use of this information may greatly improve the efficiency of ordering blood before operation.

Trigeminal neuralgia treated by radiofrequency coagulation.

Ninety-six patients underwent percutaneous radiofrequency coagulation (RC) of the Gasserian ganglion for relief of trigeminal neuralgia between 1973 and 1978. Fifty-two percent of patients who were followed for 5 years were free of recurrence after a single RC procedure. Factors predicting clinical results were sought from initial historical and demographic data. Age, sex, duration of illness, and previous response to medication were unrelated to outcome. Patients previously treated by open surgery appeared to receive less benefit from subsequent RC. The RC procedure seemed more effective in the treatment of patients with classical tic douloureux than in those with atypical features. The degree of sensory loss created by RC was associated with the clinical outcome. Patients acquiring dense sensory deficits demonstrated a reduced risk of recurrence (p = 0.006): 25% of patients with dense sensory loss and 55% of those with a partial deficit developed a recurrence by 5 years, whereas all patients without initial sensory loss suffered a recurrence by 5 years.

Yield of routine annual laboratory tests in a skilled nursing home population.

The yield of routinely performed annual panels of laboratory tests was examined among patients in the skilled nursing facility section of a large, multilevel, long-term-care institution. Of 9270 tests done as part of 336 annual panels in 121 patients over an eight-year period, 17% of the tests yielded abnormal results, and in 36% of the tests, abnormal results were new. Among the 336 panels, 56 (16.7%) had at least one abnormality that was believed to have resulted in some benefit to 30 (24.7%) of the patients. Many of the abnormalities that led to patient benefit could have been detected by periodic monitoring of chronic conditions and their treatment as opposed to true screening tests, and all such abnormalities could have been identified by a complete blood cell count, electrolyte determinations, renal and thyroid function tests, and a urinalysis. The results suggest that a modest panel of annual laboratory tests could limit the potential costs of screening and not result in the loss of potential benefits to patients in skilled nursing facilities.

Outcome of acute cholecystitis in patients with diabetes mellitus.

Prophylactic cholecystectomy has been recommended in patients who have diabetes and silent gallstones because of the reports of increased mortality resulting from acute cholecystitis in such patients. To assess recent mortality rates, we reviewed the course of acute cholecystitis in patients hospitalized between 1960 and 1981 at one hospital. Death occurred in 3 of 46 patients with diabetes and in 7 of 263 patients without the disease (p = 0.55). The age-adjusted estimate of the relative risk for death was 2.2 (95% confidence interval, 0.5 to 9.4) for diabetic compared with nondiabetic patients. All 3 diabetic patients who died had been diagnosed as having diabetes within 5 years of death, and only one had been taking insulin. Patients who had elevated blood urea nitrogen levels (greater than 20 mg/dL) were found to have an increased mortality rate when compared with patients with normal levels (27% compared with 2%; p less than 0.001). Results were similar for the outcome of serious complications. These results suggest the need for reconsideration of the recommendation for prophylactic cholecystectomy in diabetic patients with silent gallstones.

Continuous S-vO2 measurement and oxygen transport patterns in cardiac surgery patients.

Twenty adult cardiac surgery patients with impaired ventricular function by contrast ventriculography at cardiac catheterization were monitored from before anesthesia until the time of extubation up to 12 h postoperatively. A thermodilution pulmonary artery catheter with fiberoptic channels for continuous measurement of mixed-venous oxygen saturation (S-vO2) by reflection oximetry was substituted for the usual catheter. The S-vO2 was recorded continuously along with blood pressure, cardiac filling pressures, and heart rate. Thermodilution cardiac output determinations were used to derive hemodynamic and oxygen transport indices. There was a consistently high and significant negative correlation (r = -.84) between S-vO2 and the percentage of oxygen extracted from blood. Thus, S-vO2 reflects oxygen extraction and continuous S-vO2 provides continuous quantification of global oxygen extraction. None of the other oxygen transport variables including cardiac index showed significant correlation with S-vO2. The oximetry system provides a continuous and reliable indication of mixed-venous blood oxygenation which is a continuous reflection of oxygen extraction.

Analysis of relative change and initial value in biological studies.

In analyzing longitudinal data, the relationship between initial value (x1) and change in response to a maneuver or over time is often of interest. This relationship is often determined by the Pearson correlation between x1 and subsequent change (x2 - x1), but a correlation will often be obtained by mathematical necessity even when x1 and x2 are uncorrelated. It has been suggested that use of relative change, or (x2 - x1)/x1, avoids these mathematical artifacts. By reference to early work by Pearson (Proc. R. Soc. London 60: 489-498, 1897) on an approximation to the correlation between ratios and by computer simulations, this paper shows that this solution is frequently not valid. An alternative approach to the analysis of the relationship between x1 and relative change is presented and is illustrated by a study of renal blood flow.

Selection of a reference lot of Mueller-Hinton agar.

A collaborative study was undertaken to evaluate the performance of currently marketed Mueller-Hinton agars from seven manufacturers by replicate disk diffusion tests with standard quality control strains. Identification of the manufacturers was concealed, and the resulting data were evaluated for the selection of a physical reagent standard against which the performance of future production lots would be tested and made to conform. A medium was selected which was sufficiently close to existing National Committee for Clinical Laboratory Standards quality control limits that current interpretive criteria would require minimum modification. Two of the seven lots were eliminated from further consideration because the final pHs were outside acceptable limits. The remaining four lots had 96% of mean zone diameters less than or equal to 2 mm from those of the chosen lot and 65% of the means were less than or equal to 1 mm from those of the chosen lot for all 28 antimicrobial agent-organism combinations. Manufacturers then attempted to produce new lots of Mueller-Hinton agar which performed within the prescribed limits of the chosen lot. One lot performed in close conformity with the selected standard, but the overall performance of the media was essentially the same as that of the randomly chosen lots in the initial study. It was concluded that one of the original seven lots demonstrated properties which made it a tentative candidate for a physical reagent standard and that the use of a physical reagent standard in evaluating production lots might aid in stabilizing the performance of Mueller-Hinton agar.

Improved cadaveric renal transplant outcome in children.

We analyzed the results of 165 pediatric cadaver renal transplants performed at the University of California at Los Angeles to identify the factors which are linked to improved allograft survival. Both univariate life-table analysis and the Cox proportional hazard model were used. The use of a sequential immunosuppressive regimen (P less than 0.001) and kidneys from donors of more than 6 years of age (P less than 0.001) were found to be the factors having the most influence on primary graft survival. The sequential regimen was the only factor favorably influencing retransplants. With sequential therapy 1- and 2-year actuarial graft survival rates were 94% and 91% in primary transplants, and 82% and 70% in retransplants. Medication noncompliance exerted a large negative effect on transplant outcome. Of 70 recipients who had been on cyclosporine for at least 6 months, 50% evidenced noncompliance. Sixty-four percent of adolescents were noncompliant. Thirteen percent of the recipients lost their graft because of noncompliance. We conclude that good results can be obtained with cadaver renal transplants in children with a sequential immunosuppressive regimen and the use of kidneys from adolescent and adult donors. Noncompliance is a great barrier to long-term success in pediatric transplantation.