Joseph M. Garfield

Carbachol triggering of desynchronized sleep phenomena: Enhancement via small volume infusions

Two physical factors affecting the behavioral effects of drugs microinjected into the pontine tegmentum have been studied. Reducing the volume of vehicle produced a dramatic enhancement of the capacity of the long-acting cholinergic agent carbachol to induce desynchronized (D) sleep-like behavior (Dcarb). Enhancement of Dcarb was also achieved by substitute passive diffusion for active pumping of a given volume of carbachol solution. Controlling these two physical factors makes Dcarb a compelling experimental model for the study of D sleep mechanisms. The results also give support to the concept of a localized population of cholinoceptive neurons in the pontine reticular formation whose activation is a key step in the generation of physiological D.

The effect of operative technique and uterine size on blood loss during myomectomy: a prospective randomized study * †

OBJECTIVES To compare operative blood loss between two accepted blood loss-reducing techniques used during myomectomy and to evaluate the effect of preoperatively determined uterine volume on blood loss. DESIGN Subjects were stratified by ultrasound-determined uterine volume < 600 cm3 (n = 11) and > or = 600 cm3 (n = 10) and then randomized into treatment groups. The same radiologist, surgeons, and anesthetic induction technique were involved in every case. In the pharmacologic technique, diluted vasopressin (20 U in 20 mL normal saline) was injected into the serosa and/or myometrium overlying the fibroid(s) before the uterine incision(s). In the mechanical technique, a penrose drain tourniquet was passed through defects created in the broad ligaments at the level of the internal os and secured posteriorly, occluding the uterine vessels. In addition, vascular clamps were placed on the infundibulopelvic ligaments, occluding anastomotic blood flow through the ovarian vessels. RESULTS There was no difference in operative blood loss, operating time, preoperative and intraoperative mean arterial blood pressures, postoperative febrile morbidity, preoperative and postoperative hematocrits, transfusion rates, and length of hospital stay between groups. Blood loss was significantly greater for uteri with ultrasound-determined volumes > or 600 cm3 (627 +/- 175 mL, mean +/- SEM) than for those < 600 cm3 (228 +/- 49 mL). For all subjects, blood lost while operating on the uterus (mean, 379 mL; range, 35 to 1,968 mL) was positively correlated with the total weight of the fibroids resected and with time spent operating on the uterus. Total blood loss (mean, 418 mL; range, 42 to 1,968 mL) was also positively correlated with the time spent operating on the uterus and with total operating time. CONCLUSIONS There were no demonstrable differences in blood loss, morbidity, or transfusion requirements between subjects undergoing myomectomy using pharmacologic vasoconstriction and mechanical vascular occlusion techniques. Blood loss during myomectomy is primarily incurred while operating on the uterus and is correlated with preoperative uterine size, total weight of fibroids removed, and operating time.

A Comparison of Psychologic Responses to Ketamine and Thiopental–Nitrous Oxide–Halothane Anesthesia

Subjective psychologic responses to ketamine and to thiopental–nitrous oxide–halothane anesthesia, with two levels of preoperative information, were investigated in 48 young servicemen in a randomized, blind, prospective study. Ketamine produced a uniformly high incidence of illusions in both information groups, suggesting an intrinsic pharmacologic property of this drug. The combination of thiopental, nitrous oxide, and halothane also produced illusions, but their incidences were significantly lower than those with ketamine. The incidence of postoperative anxiety was no greater in patients who received ketamine than in those receiving thiopental–nitrous oxide–halothane. Patients who had received ketamine, with one exception, found the agent acceptable unless depth of anesthesia was inadequate to eliminate awareness during operation.

Addition of Sodium Bicarbonate to Lidocaine Decreases the Duration of Peripheral Nerve Block in the Rat

BackgroundAdding sodium bicarbonate to lidocaine to enhance its efficacy during peripheral nerve block is controversial. The authors studied the effect of adding sodium bicarbonate to lidocaine with and without epinephrine versus equivalent alkalinization by sodium hydroxide (NaOH) on onset, degree, and duration of peripheral nerve block. MethodsPart I examined alkalinization by sodium bicarbonate versus NaOH to pH 7.8 on 0.5% lidocaine, with and without epinephrine (1:100,000), prepared from crystalline salt. Part II examined 0.5% and 1.0% commercial lidocaine solutions, with and without epinephrine, either unalkalinized or alkalinized with sodium bicarbonate or NaOH. With NaOH, pH was adjusted to 7.8, but with sodium bicarbonate, no pH adjustments were made to simulate clinical conditions. ResultsIn part I, addition of either NaOH or sodium bicarbonate to 0.5% lidocaine without epinephrine produced a faster onset than did unalkalinized lidocaine, without effecting degree or duration of block. In solutions with epinephrine there were no differences in onset, degree, or duration between lidocaine alkalinized with sodium bicarbonate versus NaOH. In part II, addition of sodium bicarbonate or NaOH to 1.0% commercial lidocaine without epinephrine did not accelerate onset compared with the unalkalinized solution. However, adding sodium bicarbonate decreased the degree and duration of block by 25% and more than 50%, respectively, compared with lidocaine unalkalinized and alkalinized with NaOH. With epinephrine, sodium bicarbonate hastened onset without effecting degree and duration compared with the unalkalinized solution. ConclusionsWith 1% commercial lidocaine without epinephrine, sodium bicarbonate decreases the degree and duration of block. However, in solutions with epinephrine, sodium bicarbonate hastens onset, without effecting degree or duration.

Fatal Iodine Toxicity following Surgical Debridement of a Hip Wound: Case Report

This report presents the case of a patient who expired 10 hours following and emergent hip-wound debridement where Betadine, a povidone iodine solution, was used to provide continuous postoperative wound irrigation. Toxic manifestations of systemic iodine absorption appeared to cause her demise.

Effects of nitrous oxide on decision-strategy and sustained attention

Effects of 10, 20, and 30% N2O on decision-making strategy, reaction-times, sustained attention, the Digit Symbol Substitution Test (DSST), short-term memory and the Clyde Mood Scale were assessed in 12 test subjects. Decision-making strategy, as measured by 2-choice probability-learning, was unaffected by 30% N2O once a strategy had been formulated, but reaction-times were increased. Sustained attention was significantly affected in 33% of our subjects, whereas performance on the DSST and on the short-term memory task was impaired in virtually all subjects. Changes were noted in several mood-scale factors with 30% N2O. No residual drug effects were found.

United States Anesthesiologists over 50 Retirement Decision Making and Workforce Implications

Background:Anesthesiology is among the medical specialties expected to have physician shortage. With little known about older anesthesiologists’ work effort and retirement decision making, the American Society of Anesthesiologists participated in a 2006 national survey of physicians aged 50–79 yr. Methods:Samples of anesthesiologists and other specialists completed a survey of work activities, professional satisfaction, self-defined health and financial status, retirement plans and perspectives, and demographics. A complex survey design enabled adjustments for sampling and response-rate biases so that respondents’ characteristics resembled those in the American Medical Association Physician Masterfile. Retirement decision making was modeled with multivariable ordinal logistic regression. Life-table analysis provided a forecast of likely clinical workforce trends over an ensuing 30 yr. Results:Anesthesiologists (N = 3,222; response rate = 37%) reported a mean work week of 49.4 h and a mean retirement age of 62.7 yr, both values similar to those of other older physicians. Work week decreased with age, and part-time work increased. Women worked a shorter work week (mean, 47.9 vs. 49.7 h, P = 0.024), partly due to greater part-time work (20.2 vs. 13.1%, P value less than 0.001). Relative importance of factors reported among those leaving patient care differed by age cohort, subspecialty, and work status. Poor health was cited by 64% of anesthesiologists retiring in their 50s as compared with 43% of those retiring later (P = 0.039). Conclusions:This survey lends support for greater attention to potentially modifiable factors, such as workplace wellness and professional satisfaction, to prevent premature retirement. The growing trend in part-time work deserves further study.

Propofol and Ethanol Produce Additive Hypnotic and Anesthetic Effects in the Mouse

The sedative and anesthetic effects of ethanol and propofol when these drugs are coadministered are not known.Accordingly, we investigated the nature of the pharmacological interaction between ethanol and propofol during hypnosis and anesthesia in the mouse. Propofol, ethanol, and mixtures of the two were administered through the tail vein in male CD-1 mice (n = 162). The loss of righting response occurring 10 s after injection and persisting at least 10 s thereafter was defined as hypnosis, and lack of a motor response to tail clamping 60 s after injection was defined as anesthesia. The 50% effective dose (ED50) values for the hypnotic and anesthetic actions of the drugs were determined with quantal dose-response curves, using probit analysis. The pharmacological interactions were identified by the locations of ED (50) values on their corresponding hypnosis and anesthesia isoboles. For each drug alone, the hypnotic and anesthetic ED50 values with 0.95 confidence intervals were 16.70 (11.98, 23.20) mg/kg and 25.02 (20.27, 31.29) mg/kg for propofol and 0.88 (0.81, 0.95) g/kg and 1.80 (1.45, 2.23) g/kg for ethanol, respectively. For the drugs in combination, the ED50 values for hypnosis with 0.95 confidence intervals were 6.98 (6.50, 7.49) mg/kg propofol with 0.61 (0.57, 0.66) g/kg ethanol, and for anesthesia were 10.55 (9.76, 11.42) mg/kg propofol with 0.93 (0.86, 1.05) g/kg ethanol, respectively. When plotted isobolographically, we found these combinations to be behaviorally additive both for hypnosis and anesthesia. Although a finding of synergism would have excluded the possibility of an identical mechanism of action for the drugs, elucidation of the molecular basis of the additivity must await further studies. (Anesth Analg 1996;83:156-61)

Doctors in acute and longitudinal care specialties emphasise different professional attributes: implications for training programmes

Objectives  Organised medicine mandates that professionalism be taught during specialty training. This study’s primary objective was to determine the relative importance that doctors in different specialties place on different attributes of a medical professional.

Differential Effects of Ketamine Stereoisomers on Maze Performance in the Mouse

The authors studied effects of subanesthetic doses of the d- and l-ketamine stereoisomers on maze performance in mice to determine whether the stereoisomers differed in their ability to disrupt a stable cognitive behavior. Twenty-four Swiss-Webster (CFW) mice were trained to stability in a four-compartment modular maze, using water as a reward. Each compartment contained a central partition with a barrier at the distal end of one of the two passageways. A fixed barrier-sequence was employed. Elapsed time to traverse all four compartments and total number of errors (the number of times a wrong compartment was entered) were measured. A cohort design was employed with the following four groups: saline control, d-ketamine, l-ketamine, racemate. Two subanesthetic doses, 7.5 and 15 mg/kg of each form of the drug were given subcutaneously at five-day intervals. Both the d-isomer and the racemate significantly prolonged elapsed time at 15 mg/kg, the d-isomer having the greatest effect. The l-isomer did not alter elapsed time at either dose but appeared to increase spontaneous locomotor activity after injection. Relative to errors, at the 7.5 mg/kg dose there were no changes from control with any form of ketamine. However, at the 15 mg/kg dose, total errors significantly increased both with the racemate and the d-isomer. The performance decrements observed with the racemate appear to be attributable largely to the d-component.