Harry W. Linde

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.

Morphologic Changes in Mouse Spermatozoa after Exposure to Inhalational Anesthetics during Early Spermatogenesis

The authors studied anesthetic mutagenesis following exposurein vivo by use of an adaptation of the mouse spermatozoa morphology assay of Wyrobek and Bruce. The epididymal spermatozoa of (C57B1/C3H)F1 mice were examined for morphologic abnormalities following exposure to near-0.1 MAC and greater concentrations of general anesthetics. Twenty exposure hours (4 hr/day × 5 days) were conducted for nitrous oxide, diethyl ether, chloroform, trichloroethylene, halothane, methoxyflurane, enflurane, and isoflurane, each at two concentrations. Twenty-eight days after exposure, epididymal spermatozoa were examined. Statistically significant increases in the percentages of abnormal spermatozoa were found for chloroform, trichloroethylene, and enflurane, compared with controls. These data suggest that direct examination of reproductive cells following exposure to general anestheticsin vivo may be useful in the investigation of the genetic toxicities of these compounds.

A new anesthetic agent - Forane: preliminary observations in man

HE continuing search for better inhalaT tion anesthetics has resulted in the clinical evaluation of several short-chain halogenated hydrocarbons and ethers. Initial studies in animals have shown promising results with one of these, a nonflammable fluorinated ether, Ohio Compound 469 ( CHF2-O-CHC1-CF,), now named Forane.@’ Forane is an isomer of enflurane, with physical properties similar to those of enflurane and halothane (table 1). Vitchal has pointed out that, compared with currently available halogenated compounds, Forane exhibits unusual chemical stability,

Status of Women in Academic Anesthesiology

The authors compared anesthesia faculties with the rest of medical school faculties at each of four academic ranks and found a significant difference in proportion of men and women anesthesia faculty members at the assistant professor rank only (P < 0.001). When the faculty status of women and men academic anesthesiologists was examined a significant difference was found in rank distribution in age groups 40 to 44 (P < 0.005) and 45 to 49 (P < 0.001), where there was a deficit of professors and a surfeit of instructors among women. Significant differences in distribution continued at age 50–54 (P < 0.01), 55–59 (P < 0.001), and 60–64 (P < 0.005), primarily at professor and assistant professor ranks. In addition, there was significantly lower prevalence of board certification (P < 0.001) and level of responsibilities for women (P < 0.001). There was no significant difference in tenure status.

Vaporization of Mixed Anesthetic Liquids

The results of erroneous filling of agent-specific anesthetic vaporizers were studied. The fraction of gas flow through the vaporizer was calculated for three vaporizers set to deliver essentially equipotent final concentrations: halothane, 1% (1.25 MAC); enflurane, 2% (1.19 MAC); and isoflurane, 1.5% (1.30 MAC). These fractional flows, at 22 degrees C, were 0.0188 for 1% halothane, 0.0615 for 2% enflurane, and 0.0295 for 1.5% isoflurane. Concentrations were calculated for cases of total filling of a vaporizer with one of the other two agents. In terms of potency of delivered agent, fourfold underdoses or overdoses could result from such errors. Refilling a 25% full vaporizer with the wrong agent then was considered. In order to calculate the concentrations of each agent that would be delivered in such a case, vapor pressures of each were determined in mixtures of two agents. Enflurane and isoflurane could not be separated satisfactorily by gas chromatography. Halothane, when mixed with enflurane or isoflurane, enhanced vaporization of each agent, as well as being somewhat more easily vaporized itself. Halothane, enflurane, and isoflurane do not form ideal solutions when mixed and the resultant vapor concentrations of each of two agents when mixed may be far from those predicted by an assumption of ideality.

Postdural Puncture Headache in Patients with Chronic Pain

The incidence of headache after dural puncture in patients being treated for chronic pain was studied prospectively. Dural punctures were performed in 142 patients and headache developed in 13 (9.2%). Four of 32 patients (12.5%) who underwent diagnostic differential spinal and nine of 110 patients (8.2%) given intrathecal steroid injection developed headache. There was a 10.7% incidence of headache when a 22-gauge needle was used as compared to 5% with a 25-gauge needle. This difference was not statistically significant. The incidence decreased with increasing age. The incidence of postdural puncture headache in chronic pain patients does not differ significantly from that previously reported for surgical patients. All patients who developed headache responded to treatment which consisted of intravenous and oral fluids, analgesics, bed rest, and, if necessary, epidural blood patch.

Causes of death among anesthesiologists: 1930-1946

The causes of death among anesthesiologists from 1930 through 1946 were determined and compared to the causes of death for contemporaneous physicians as well as anesthesiologists in later eras. Names of US white male anesthesiologists listed in the annual Directories of Anesthetists compiled by the International Anesthesia Research Society were searched for in the death files of the American Medical Association. Among those listed in the Directories 274 deaths were located. Causes were ascertained for 269 deaths and 259 causes were verified from death certificates. The leading causes of death of anesthesiologists and other physicians of the same era were cardiovascular-renal diseases and malignant neoplasms. The death rate from all causes was lower among anesthesiologists than among contemporaneous white men and other physicians. Death rates among anesthesiologists from 1930–1946 were similar to those among anesthesiologists in 1947–1956, but greater than those for 1957–1971. Among deaths from malignant neoplasms, those of the digestive organs were the most frequent and those of the respiratory tract the least. Anesthesiologists practicing in the earlier part of this century had lower death rates and they were less likely to die of malignant neoplasms than contemporaneous white men. The death rates for these anesthesiologists were similar to those for anesthesiologists during 1947–1956, but greater than rates observed for anesthesiologists during 1957–1971. This suggests that exposure to the fluorinated anesthetic agents introduced in the mid-1950s may not be an important health hazard.

Cardiovascular effects of isoflurane and halothane during controlled ventilation in older patients.

Isoflurane or halothane was administered at twyo different inspired concentrations to 21 surgical patients whose average age was 62 years. Most were in physical status (ASA) II or III. Patients were premedicated with diazepam and atropine, anesthesia was induced with thiopental, and tracheal intubation was facilitated with succinylcholine. Respiration was controlled manually or with a ventilator. Anesthesia was maintained with 60 percent N2O and halothane 1 percent, then 0.5 percent, or with N2O-isoflurane 1.2 percent, then 0.6 percent in O2. Variations in the cardiovascular responses among patients given the same anesthetic were as great as the variation in responses between anesthetics. Both produced similar decreases in arterial pressure, cardiac output, and stroke volume. Changes in pulse rate were minimal, and total peripheral resistance changes quite variable, for both drugs.Both halothane and isoflurane appear satisfactory for inhalation anesthesia in the elderly.

VENTRICULAR FUNCTION AND AUTONOMIC NERVOUS ACTIVITY DURING CYCLOPROPANE ANESTHESIA IN MAN

In 1949 Moe, Rennick, Freyburger and Malton expressed surprise at the prevalent clinical use of cyclopropane, because its administration appeared to reduce cardiac contractility conspicuously in both intact dogs and canine heart-lung preparations (1). The effects of cyclopropane in heart-lung preparations have been repeatedly confirmed (2-4), but uncertainty attaches to measurements of cardiac contractility made during cyclopropane anesthesia in intact animals because they indicate every possible result from stimulation to pronounced depression (5-7). Since the question of cardiac competence during cyclopropane anesthesia achieves practical importance only when it relates to man, we believe it essential that it be answered in man. What follows is the result of an attempt to do so.

Hemodynamic and catecholamine responses associated with extracorporeal shock wave lithotripsy

Patients undergoing extracorporeal shock wave lithotripsy (ESWL) for nephrolithiasis are anesthetized and immersed in water in a semisitting position. Hypertension and tachycardia have been reported to accompany ESWL, and it was hypothesized that those problems were a result of adrenal medullary release of epinephrine or norepinephrine. Therefore, the effects of ESWL on cardiovascular variables and circulating epinephrine and norepinephrine levels in nine patients anesthetized with 1.1% isoflurane in 50% nitrous oxide and oxygen were studied. End-tidal carbon dioxide (CO2) was maintained at 34 +/- 2 mmHg. Cardiac output (CO) and mean arterial pressure (MAP) were measured, and total peripheral resistance (TPR) was calculated at the following time points: (1) after immersion prior to shock wave therapy (control); (2) after 300 shocks; (3) after 800 shocks; and (4) 5 minutes after the completion of ESWL with the patient still immersed. Circulating epinephrine and norepinephrine concentrations were determined at the above times as well as before and after induction of anesthesia but prior to immersion. There was a statistically significant (p less than 0.05) decrease in CO and an increase (p less than 0.05) in MAP and TPR with ESWL treatment. These values returned to baseline levels when treatment was stopped. Plasma epinephrine and norepinephrine values did not change significantly throughout the study period. It was concluded that these ESWL-associated hemodynamic changes were probably not mediated via epinephrine or norepinephrine.