Practicality of using galvanic skin response to measure intraoperative physiologic autonomic activation in operating room team members.

BACKGROUND: Physiologic and psychological stress are commonly experienced by operating room (OR) personnel, yet there is little research about the stress levels in OR teams and their impact on performance. Previously published procedures to measure physiologic activation are invasive and impractical for the OR. The purpose of this study was to determine the practicality of a new watch-sized device to measure galvanic skin response (GSR) in OR team members during high-fidelity surgical simulations. METHODS: Interprofessional OR teams wore sensors on the wrist (all) and ankle (surgeons and scrub nurses/technicians) during the orientation, case, and debriefing phases for 17 simulations of a surgical airway case. Data were compared across all simulation phases, collectively and for each professional group. RESULTS: Forty anesthesiology residents, 35 surgery residents, 27 OR nurses, 12 surgical technicians, and 7 CRNAs participated. Collectively, mean wrist GSR levels significantly increased from orientation phase to the case (0.40-0.62 µS; P < .001) and remained elevated even after the simulation was over (0.40-0.67 µS; P < .001). Surgery residents were the only group that demonstrated continued increases in wrist GSR levels throughout the entire simulation (change in GSR = 0.21 to 0.32 to 0.11 µS; P < .01). Large intraindividual differences (≤ 200 times) were found in both wrist and ankle GSR. There was no correlation between wrist and ankle data. CONCLUSION: Continuous GSR monitoring of all professionals during OR simulations is feasible, but would be difficult to implement in an actual OR environment. Large variation in individual levels of physiologic activation suggests complementary qualitative research is needed to better understand how people respond to stressful OR situations.

Severe glottic stenosis in a parturient with ectodermal dysplasia.

Airway stenosis in pregnancy is challenging and the literature does not offer consensus regarding its evaluation and anesthetic management. A 21-year-old nulliparous woman with ectodermal dysplasia and severe glottic stenosis was referred to the obstetric anesthesia team for evaluation and peripartum management recommendations. She had a history of a congenital complete glottic web that required a tracheostomy at birth. After decannulation at age four, she was lost to follow-up. On examination in early pregnancy, she was found to have a dangerously narrow airway with fixed vocal cords and a glottic aperture of 2-3mm. At nine weeks of gestation an elective tracheostomy was performed under local anesthesia. She later underwent an uneventful cesarean delivery under spinal anesthesia. Ultimately, early interdisciplinary planning for an elective tracheostomy helped assure patient safety during advancing pregnancy and delivery.

A cross-cultural survey of residents' perceived barriers in questioning/challenging authority.

OBJECTIVES: To identify perceived barriers to residents' questioning or challenging their seniors, to determine how these barriers affect decisions, and to assess how these barriers differ across cultures. METHOD: A written questionnaire was administered to residents in teaching hospitals in the US and Japan to assess factors affecting residents' willingness to question or challenge their superiors. The responses were analyzed for statistical significance of differences between the two cultures and to determine the importance of issues affecting decisions. RESULTS: Questionnaires were completed by 175 US and 65 Japanese residents, with an overall response rate of 71%. Trainees from both countries believe that questioning and challenging contribute to safety. The perceived importance of specific beliefs about the workplace differed across cultures in seven out of 22 questions. Residents' decisions to make a challenge were related to the relationships and perceived response of the superiors. There was no statistical difference between the US and Japanese residents in terms of the threshold for challenging their seniors. CONCLUSION: We have identified attributes of residents' beliefs of communication, including several cross-cultural differences in the importance of values and issues affecting one's decision to question or challenge. In contrast, there was no difference in the threshold for challenging seniors by the Japanese and US residents studied. Changes in organizational and professional culture may be as important, if not more so, than national culture to encourage "speaking up". Residents should be encouraged to overcome barriers to challenging, and training programs should foster improved relationships and communication between trainers and trainees.

Hemodynamic effects of spinal anesthesia and simultaneous intravenous bolus of combined phenylephrine and ephedrine versus ephedrine for cesarean delivery.

BACKGROUND: Hypotension following spinal anesthesia for cesarean delivery can produce adverse maternal symptoms and neonatal acid-base effects. Single-agent prophylaxis, most notably with ephedrine, does not reliably prevent spinal anesthesia-induced hypotension; recently, however, the prophylactic use of phenylephrine with ephedrine as an infusion was observed to be effective. We postulated that this combination, when given as an intravenous bolus for prophylaxis and rescue treatment, could be similarly effective. METHOD: Forty-three term parturients were randomized to receive a bolus of ephedrine 10 mg +/- phenylephrine 40 microg (groups E and EP, respectively) simultaneously with spinal anesthesia. Hypotension was defined as a systolic blood pressure below 100 mmHg or a decrease of 20% from a baseline value. Rescue boluses comprised of ephedrine 5 mg +/- phenylephrine 20 microg. RESULTS: For groups E and EP, respectively, the incidence of hypotension was 80% vs. 95% (P=0.339), with the mean number of rescue boluses being 3.85+/-3.7 and 3.05+/-1.7 and the mean umbilical artery pH being 7.246+/-0.081 vs. 7.244+/-0.106. All comparisons were not significant (NS). CONCLUSION: The combination of ephedrine and phenylephrine given as an intravenous bolus at the doses selected is not superior to ephedrine alone in preventing or treating hypotension in healthy parturients undergoing cesarean delivery.

Mobilization of Ca2+ from intracellular stores of pancreatic beta-cells by the calcium store blocker TMB-8.

TMB-8 has been used experimentally in many cell types, including endocrine cells, because of its ability to block the efflux of Ca2+ from intracellular stores without affecting influx. Unexpectedly, TMB-8 potentiates stimulated insulin release from pancreatic islets, a process believed to be dependent on the level of cytosolic Ca2+. In the present study, while having no effect on basal insulin release (in the presence of 2.8 mM glucose), TMB-8 (10, 30, and 100 microM) caused a concentration-dependent increase in 45Ca2+ efflux from 45Ca2+-preloaded islets. TMB-8 (100 microM) stimulated 45Ca2+ efflux even in the absence of extracellular Ca2+. In the presence of 5.6 mM glucose, TMB-8 (30 and 100 microM) potentiated insulin release and again increased 45Ca2+ efflux in a concentration-dependent manner. Similarly, insulin release stimulated by isobutylmethylxanthine (IBMX) was potentiated significantly, and IBMX-stimulated 45Ca2+ efflux was increased by the simultaneous introduction of 30 microM TMB-8. Thus, in pancreatic islets, TMB-8 appears to mobilize Ca2+ from intracellular stores, rather than inhibit the efflux as has been commonly accepted. In further studies, using insulin-secreting beta-cells of the RINm5F cell line, TMB-8 was shown to increase the cytosolic Ca2+ concentration in the presence and absence of extracellular Ca2+. This confirmed that mobilization of intracellular Ca2+ was occurring in the pancreatic beta-cell in response to TMB-8. Furthermore, a rise in cytosolic Ca2+ of not more than 10 nM (as induced with KCl) was found to mimick the effect of TMB-8 in conjunction with IBMX. No additional effect of TMB-8 to alter Ca2+ handling at the plasma membrane was found when 45Ca2+ uptake experiments were performed. Therefore, the paradoxical mobilization of beta-cell Ca2+ by TMB-8 appears to be a sufficient explanation for its potentiating effect on the rate of insulin secretion.

Development of the biphasic response to glucose in fetal and neonatal rat pancreas.

A study on the development of biphasic insulin release and sensitivity to inhibitors has been performed using perifused rat pancreas at 19.5 days of gestation (3 days before birth) and at 3 days after birth. In the fetal pancreas, 16.7 mM glucose caused a marked stimulation of insulin release that did not, however, manifest a biphasic response and was not inhibited by verapamil, a Ca2+ channel blocker. This suggested that the immature response was due to either a lack of voltage-dependent Ca2+ channels or their failure to open in response to glucose. Depolarizing concentrations of KCl stimulated insulin release, which was inhibited by verapamil, demonstrating that functional Ca2+ channels were present. In the presence of 16.7 mM glucose, quinine, which blocks glucose-sensitive k+ channels, potentiated the response of the fetal pancreas that now became sensitive to verapamil, demonstrating that functional K+ channels were also present in the fetal pancreatic beta-cell. The immaturity of the response is not due specifically to a defect in glucose metabolism; rather the metabolism of nutrient secretagogues fails to couple with the K+ channel in the fetal islet and thus fails to depolarize the beta-cell membrane. Three days after birth the pattern of response to high glucose is biphasic. Insulin release in fetal pancreas was inhibited by epinephrine and somatostatin.

Effects of tetracaine on insulin release and calcium handling by rat pancreatic islets.

The effects of tetracaine on insulin release and 45Ca2+ handling by rat pancreatic islets have been studied under basal (2.8 mM glucose), glucose-stimulated (5.6, 8.3, and 16.7 mM glucose), and 3-isobutyl-1-methylxanthine (IBMX)-stimulated conditions. Islets were isolated by the use of collagenase and used either directly (freshly isolated islets) or after a period under tissue culture conditions. Tetracaine was found to stimulate insulin release under basal conditions, to inhibit glucose-stimulated insulin release, and to potentiate insulin release stimulated by IBMX. In studies on the mechanisms underlying these effects, tetracaine was found to decrease glucose-stimulated net retention of 45Ca2+ (by an action to block the voltage-dependent Ca channels) and to mobilize Ca2+ from intracellular stores. These two actions form the basis for the inhibition of glucose-stimulated insulin release, which depends heavily on Ca2+ entry via the voltage-dependent channels and the synergism with IBMX to potentiate release. No inhibition of IBMX-stimulated release occurs because IBMX does not use the voltage-dependent channels to raise intracellular Ca2+.

Paradoxical potentiation of stimulated insulin release by dantrolene in rat pancreatic islets.

Dantrolene sodium, used clinically as a muscle relaxant because of its ability to block Ca2+ efflux from sarcoplasmic reticulum, was used to study the role of intracellular stored Ca2+ in the stimulation of insulin release from rat pancreatic islets. Under basal conditions (2.8 mM glucose), dantrolene (25 microM) decreased 45Ca2+ efflux by 40% without affecting the rate of insulin release. When the islets were exposed to a submaximal stimulatory concentration of glucose (8.3 mM), dantrolene potentiated insulin release. When a supermaximal concentration of glucose (33.3 mM) was used, dantrolene neither increased nor decreased the maximal rate of insulin release. In all cases studied, 45Ca2+ efflux was depressed by dantrolene. 3-Isobutyl-1-methyl-xanthine (IBMX) a phosphodiesterase inhibitor, stimulated insulin release and caused a transient increase in 45Ca2+ efflux from preloaded islets in accord with the idea that it mobilizes Ca2+ from an intracellular store. Dantrolene inhibited IBMX-induced 45Ca2+ efflux and potentiated IBMX-stimulated insulin release. That dantrolene acts to trap calcium in stores is supported by wash-out experiments in which, under basal conditions, removal of the drug after a preincubation period increased both insulin release and 45Ca2+ efflux. The apparent contradiction that a calcium store blocker potentiates insulin release is reconciled by the hypothesis that dantrolene, by filling intracellular Ca2+ stores, causes them to regulate cytosolic Ca2+ at a higher set point.