Metocurine kinetics in patients undergoing operations requiring cardiopulmonary bypass.

Metocurine kinetics were determined in 10 patients undergoing operations requiring hypothermic cardiopulmonary bypass (CPB) and nine patients of similar age undergoing operations of similar duration but not requiring CPB. The metocurine dosage regimen was a bolus of 0.3 mg/kg given concomitantly with the commencement of an infusion at a rate of 0.04 mg/kg/hr; this regimen was designed to produce and maintain a plasma metocurine concentration associated with 95% depression of the twitch response. Metocurine kinetics were affected minimally by hypothermic CPB. The kinetic parameters including volumes of distribution at steady state of 0.35 L/kg and 0.34 L/kg and elimination clearances of 1.3 ml/min/kg and 1.1 ml/min/kg in the control and CPB groups, respectively, are in agreement with the results of others. Changes in neuromuscular blockade with the onset of CPB and the return to original blockade intensities with rewarming suggest a decreased sensitivity to the effects of metocurine at lower temperatures.

Optimal transcranial magnetic stimulation sites for the assessment of motor function.

The optimal placement sites for eliciting motor evoked potentials from the abductor digiti minimi and abductor hallucis muscles by means of transcranial magnetic stimulation were determined using a commercially available circular coli. Fifty volunteers were used for the study. The ability to elicit responses was found to be strongly dependent upon the scalp placement of the stimulator coil. The effects of altering the direction of current flow in the coil were tested on two different sets of volunteers: clockwise in one and counterclockwise in the other. It influenced only the locations of the sites which were optimal for eliciting responses from the abductor hallucis muscles and not those which were optimal for eliciting responses from the abductor digiti minimi muscles. Response latencies were found to be significantly dependent only upon volunteers' heights and not on their sex, age, or weight or the stimulus intensities used to elicit responses. No previous studies have defined the optimal scalp placements for eliciting responses from the lower extremities. This information may have clinical importance for making reliable assessments of patients with significantly impaired motor function.

Improving autologous blood harvest: recovery of red cells from sponges and suction.

The efficacy of red cell salvage was assessed under circumstances which simulated blood loss managed with sponges or suction. Expired banked blood was equally divided and processed by either suction, or absorbing the blood on a sponge followed by rinsing the sponge in saline. These two techniques were used to harvest washed, centrifuged erythrocytes. The volume, haematocrit and free haemoglobin concentration of the banked blood and the processed units were measured, and smears from all units were examined microscopically. The red cell mass was calculated as the product of the volume and haematocrit. The red cell mass recovered by suction and from sponges averaged 93% and 87% respectively. Blood lost in sponges can be recovered and used to increase the available autologous blood, thereby reducing the need for donor blood.

The pharmacokinetics of d-tubocurarine with surgery involving salvaged autologous blood.

The disposition of d-tubocurarine (dTc) was assessed when a bolus and infusion dosage regimen was used to obtain relaxation during major orthopedic surgery on the spine. Renal clearance of dTc was 0.63 +/- 0.23 ml X min-1 X kg-1 and was correlated with creatinine clearance. Total plasma clearance of 1.21 +/- 0.40 ml X min X -1 X kg-1 was lower than that found in many previous studies, and the predetermined continuous dTc infusion produced an apparent plateau in plasma concentrations of 1.8 +/- 0.3 micrograms X ml-1. Despite the operative blood loss, these concentrations were greater than anticipated and were associated with a more intense neuromuscular blockade than the infusion was designed to produce. Autologous blood transfusion was used to reduce the reliance on homologous donor blood, and the erythrocytes from the 2.2 +/- 1.2 1 of blood loss during the procedure were reinfused after intraoperative salvage, washing, and centrifugation. With 80 +/- 23 mg dTc administered, 1.4 +/- 0.8% was recovered from the fluid discarded after centrifugation. These results indicate that even massive intraoperative blood loss will not entail a significant reduction in the amount of dTc present in the body.

Relationship between past academic performance and results of specialty in-training examinations.

In this study, the authors review the records of 63 graduates of Northwestern University Medical School who were residents in its graduate medical education programs of anesthesia and orthopedic surgery. They examine the relationship among college grades, medical school performance, and the results of assessment by annual, nationwide, medical specialty in-training examinations. For the anesthesia group, the best predictors of in-training examination performance were the Medical College Admission Test (MCAT) Verbal Ability score, the college grade-point average for nonscience subjects, and the MCAT Science, General Information, and Quantitative Ability scores. For the orthopedic group, the best predictors were the MCAT Verbal Ability score, the college grade-point average in nonscience subjects, the MCAT Science score, and the National Board of Medical Examiners Part I and Part II examination scores. The previous academic records for the 63 residents contained little to presage results in the in-training examination. The correlation obtained between nonscience college subjects and the in-training examination results was negative.

Statistical methods in anesthesia articles: an evaluation of two American journals during two six-month periods.

Simple criteria were used to evaluate the statistical analyses in 243 articles from two American anesthesia journals published in the latter six months of 1981 and 1983. Eighty-two percent of the articles reported the use of control measures and 37% reported randomization of treatment, where they were possible. Data were classified as nominal, ordinal, or interval; as independent or related samples; as two-sample or more-than-two-sample cases. The descriptive, inferential, and correlative tests used were evaluated for appropriate application and primary errors were identified. Nine percent of the 722 descriptive statistics had major errors, most of which were a description of ordinal data as though they were interval. The incidence of erroneous applications of 394 inferential statistical tests was 78%. Nearly three-quarters of the 308 primary inferential statistical errors involved either use of a test for independent samples on related data (and vice versa) or multiple applications of an uncorrected test to the same data. Only 4% of the 113 statistics of association were considered erroneous, most because the method was not identified. No differences were detected in the incidence of errors in either experimental design or statistical analysis across time or across the two anesthesia journals. Fifteen percent of the 243 articles in both journals at both times were without major errors in statistical analysis. Recognition of potential sources of error should make it easier for investigators to use experimental designs and statistical analyses appropriate to their needs.

A multicenter study of the prevalence of hepatitis B viral serologic markers in anesthesia personnel.

Health care workers with frequent blood contact are at high risk of infection with hepatitis B virus. We surveyed 154 physician anesthesiologists (MD) and certified registered nurse anesthetists (CRNA) at four university-affiliated medical centers to determine the prevalence of serologic markers of hepatitis B virus (HBV). Questionnaires were used to ascertain historical and demographic information, nonoccupational risk factors, and characteristics of the participants' anesthesia practice. The overall prevalence of seropositivity was 18.8% (range 10.2-30.3%), and there were no statistically significant differences among the four centers, MD and CRNA groups, or males and females. In contrast to other studies, the prevalence of seropositive markers did not increase with an increase in the participants' age or length of time in the specialty. For the groups sampled in this study, geographic location or type of practice did not influence the increased prevalence of HBV seropositivity in anesthesia personnel. The current methods of HBV infection control were not associated with a decreased prevalence of serum markers. The majority of the susceptible anesthesia personnel at these four institutions did not plan to receive the hepatitis B vaccine when surveyed at the time of this study.