David L. Bruce

Trace Anesthetic Effects on Perceptual, Cognitive, and Motor Skills

Twenty males, paid volunteer medical or dental students were exposed on two occasions to four hours of inhalation of either air or 500 ppm nitrous oxide and 15 ppm halothane in air. Immediately following this, a battery of tests of perceptual cognitive and motor skills were administered to them. Evaluating their responses compared to their control conditions when they breathed only air, there was a significant decrement in performance following anesthetic exposure on a task of divided attention between auditory and visual signals, a visual tachistoscopic test, and memory tests involving digit span and recall of word pairs. These findings may indicate a subtle but significant negative effect on the ability of anesthesiologists to provide vigilant care for their patients. Further investigation of possible long-term effects upon the effective function and accident record of the anesthetist is indicated.

Causes of death among anesthesiologists: a 20-year survey.

During the years 1947–1966, there were 441 deaths among junior, active and retired members of the American Society of Anesthesiologists living in the United States or Canada. A cause of death was found for each member and death rates calculated for this group. Comparisons of these rates with those for U. S. males and with male policyholders of the Metropolitan Life Insurance Company were made. Anesthesiologists appear to have a low incidence of lung cancer, a somewhat lower than average incidence of coronary artery disease in recent years, and a high death rate from suicide and malignancies of the lymphoid and reticuloendothelial tissues. These data only suggest trends and point to the need for a prospective study of this subject.

Psychological studies of human performance as affected by traces of enflurane and nitrous oxide.

Thirty human subjects were exposed for four hours to 500 ppm N-2O and 15 ppm enflurane in air and then, within five minutes, given a 35-minute battery of psychological tests. Performance of a divided-attention audiovisual task and a digit-span memory test were significantly decreased compared with control data following exposure to air. A tachistoscopic task, four tests from the Wechsler memory scale, and five others from the Wechsler Adult Intelligence Scale were unaffected. Thirty subjects exposed to 500 ppm N-2-O in air only scored significantly lower on the digit-span test only.

A prospective survey of anesthesiologist mortality, 1967-1971.

During the years 1967–1971, there were 211 deaths among junior, active and retired members of the American Society of Anesthesiologists living in the United States and Canada. A cause of death was verified for each of these members, and death rates according to categories were calculated for them. Comparison of these rates with those of male standard ordinary policyholders of the Metropolitan Life Insurance Company were made. The death rates, both overall and by categories, of anesthesiologists were lower than those for the control group, with the exception of suicide.

Halothane inhibition of phytohemagglutinin-induced transformation of lymphocytes.

Phytohemagglutinin activation of human peripheral lymphocytes to synthesize DNA was inhibited in a dose-dependent manner by the presence of halothane in the cell culture. This occurred at concentrations of halothane approximating those found in arterial blood during clinical anesthesia. Tests of cell viability showed that these levels of halothane did not kill the cells in culture. The studies support, but do not prove, the hypothesis that halothane prevents resting cells from entering the cell cycle when signalled to do so.

Effect of halothane anesthesia on the human cortical visual evoked response.

The visual evoked response (VER) was monitored in eight women intraoperatively during anesthesia with halothane in oxygen administered via endotracheal tube. Control measurements were made prior to anesthetic induction in these unpremedicated patients. The latency of the positive peak designated PI increased progressively from a mean of 113 ± 10 (SD) msec in the awake state to the following values at indicated end-tidal halothane concentrations: 123 ± 10 msec at 0.75 per cent; 130 ± 9 msec at 0.90 per cent; 134 ± 9 msec at 1.13 per cent. The differences among mean latency values at these anesthetic concentrations were insufficient to conclude that VER latency would be a useful monitor of anesthetic depth. However, significant effects were seen at clinical levels of halothane anesthesia, and the prolongation caused by anesthesia must be considered when using VERs to monitor central nervous system function during neurosurgery.

Thiopental and succinylcholine: Action on intraocular pressure.

&NA; Intraocular pressure (IOP) measurements were made in a series of 92 male surgical patients, to assess the effects of timing and dosage of succinylcholine given after a standardized sleep dose of thiopental (3 mg./kg.). The major findings of this study were as follows: (1) thiopental alone lowered IOP; (2) a small (0.5 mg./kg.) dose of succinylcholine, given immediately after thiopental, returned IOP to normal; (3) a large (1 mg./kg.) dose of succinylcholine immediately after thiopental maintained the IOP at a low value; (4) if 2 minutes elapsed between thiopental and 1 mg./kg. of succinylcholine, the relaxant raised the IOP to slightly above preanesthetic control values; (5) tracheal intubation caused a significant rise in IOP, more than any effect from succinylcholine itself; (6) succinylcholine drip (0.1 percent), begun after establishment of satisfactory endotracheal halothane‐nitrous oxide anesthesia, caused significant IOP elevation in 4 of 11 patients.

Alcoholism and Anesthesia

Alcoholism has only recently come to be recognized as a disease and been given time in medical school curricula. Even today, there are many physicians who discount the disease paradigm of this prevalent disorder. Accordingly, anesthesiologists who encounter alcoholic patients often do so in ignorance of important information. This review attempts to update the knowledge of such clinicians. Its need is underscored by a recent report from the Institute of Medicine, National Academy of Sciences (1), from which the following excerpts are taken: there are an estimated 12 million American problem drinkers; estimates of deaths related to alcohol abuse range from 50,000-200,000 annually; health complications related to alcohol abuse include cardiac arrhythmias and sudden death, cardiomyopathy, cirrhosis, gastritis, hepatitis, malnutrition, pancreatitis, and a wide range of psychiatric disorders; alcohol figures prominently in causes of accidents, crime, fires, homicides, and suicides; and estimates of the annual economic cost of alcohol abuse range from 40-60 billion dollars annually in the United States. Any disorder with these features deserves serious study by all physicians. Anesthesiologists have a particular need to know about alcoholism because they treat alcoholics in diverse critical care situations.

Halo thane Inhibition of RNA and Protein Synthesis of PHA-treated Human Lymphocytes

Cultured human lymphocytes treated with phytohemagglutinin (PAH) ahd higher rates of RNA and protein synthesis, as judged by incorporation of the labelled precursors -3H-URIDINE AND -14C-leucine, than did control cultures without PHA. These cultures were prepared from cells of the same donor, as were a third set of cultures which were equilibrated with 2 per cent halothane. The increased rates of RNA and protein synthesis six and 16 hours after PHA ADDITION WERE INHIBITED BY THE HALOTHANE, MODESTLY AT SIX HOURS AND STRIKINGLY AT 16 HOURS. These experiments provide further evidence that halothane prevents recruitment of resting cells into the active cycle of cell division.

Murine fertility unaffected by traces of halothane.

Male and female mice of three different strains were exposed to air or air containing 16 ppm halothane and allocated to one of four treatment groups: male and female both receiving air; male, halothane in air and female, air; male, air and female, halothane in air; both male and female, halothane in air. Exposure lasted seven hours daily, five days a week, for six weeks. Animals were then paired according to treatment groups, individually exposed daily to the same conditions as previously, but caged with their mates each night. After 18 days, all mice were sacrificed. Splenic weights were determined for all males, and necropsies of one third of each treatment group were done for histologic examination of the liver, spleen, and testis. Total number of pregnancies, implantations per pregnancy, and resorptions per pregnancy were determined by necropsy of the females. Fetuses were prepared for examination to detect skeletal anomalies. Halothane, at concentrations known to exist in ambient operating room air, did not have any deleterious effect on rodent reproduction.