N. Higgins

Acquisition of critical intraoperative event management skills in novice anesthesiology residents by using high-fidelity simulation-based training.

Background:Early acquisition of critical competencies by novice anesthesiology residents is essential for patient safety, but traditional training methods may be insufficient. The purpose of this study was to determine the effectiveness of high-fidelity simulation training of novice residents in the initial management of critical intraoperative events. Methods:Twenty-one novice residents participated in this 6-week study. Three hypoxemia and three hypotension scenarios were developed and corresponding checklists were validated. Residents were tested in all scenarios at baseline (0 weeks) and divided into two groups, using a randomized crossover study design. Group 1 received simulation-based training in hypoxemic events, whereas Group 2 was trained in hypotensive events. After intermediate (3 weeks) testing in all scenarios, the groups switched to receive training in the other critical event. Final testing occurred at 6 weeks. Raters blinded to subject identity, group assignment, and test date scored videotaped performances by using checklists. The primary outcome measure was composite scores for hypoxemia and hypotension scenarios, which were compared within and between groups. Results:Baseline performance between groups was similar. At the intermediate evaluation, the mean hypoxemia score was higher in Group 1 compared with Group 2 (65.5% vs. 52.4%, 95% CI of difference 6.3–19.9, P < 0.003). Conversely, Group 2 had a higher mean hypotension score (67.4% vs. 45.5%, 95% CI of difference 14.6–29.2, P < 0.003). At Week 6, the scores between groups did not differ. Conclusions:Event-specific, simulation-based training resulted in superior performance in scenarios compared with traditional training and simulation-based training in an alternate event.

A randomized controlled trial of the impact of simulation-based training on resident performance during a simulated obstetric anesthesia emergency.

Introduction: The percentage of patients having cesarean delivery (CD) under general anesthesia has decreased, which may have implications for residency training in anesthesiology. We undertook this study to assess the effect of focused simulation-based training on resident performance during a simulated general anesthetic for emergency CD. Methods: Thirty-two second-year anesthesiology resident volunteers were randomly assigned to one of the two groups: a group trained on the patient simulator performing general anesthesia for emergency CD (CD group) and a control group trained on the simulator using a different general anesthetic scenario unrelated to obstetric anesthesia (SHAM group). Between 6 and 9 weeks, all the residents performed the emergency CD scenario on the simulator and were videotaped. Two blinded observers scored the videotaped performances using a valid and reliable scoring system separately and were blinded to each others score. The time interval from the start of the scenario until the simulated surgical incision was noted. Total scores and component scores in six subcategories were compared between resident groups, as was the start to incision time interval. Results: Residents in the CD group had higher total scores and higher scores in the preoperative assessment, equipment availability check, and intraoperative management before delivery subcategories than residents in the SHAM group. The start to incision time interval did not differ between the groups. Conclusions: Anesthesiology residents who underwent focused training on a simulator that included performance of a general anesthetic for emergency CD exhibited improved performance during a subsequent simulated anesthetic scenario compared with trainees who did not undergo such instruction.

The Berlin Questionnaire for assessment of sleep disordered breathing risk in parturients and non-pregnant women

BACKGROUND Pregnancy is associated with alteration in sleep patterns and quality. We wished to investigate whether pregnant women have a higher likelihood of a positive Berlin Questionnaire than non-pregnant women. METHODS Pregnant women ages 18-45 years (n=4074) presenting for delivery, and non-pregnant women ages 18-45 years (n=490) presenting for outpatient surgery provided demographic information and completed the Berlin Questionnaire evaluating self-reported snoring and daytime sleepiness. For the pregnant patients, the infants birth weight and Apgar scores were also recorded. RESULTS Of the 1439 patients with a positive Berlin Questionnaire, 96 were in the non-pregnant control population versus 1343 in the pregnant population (20% vs. 33%, respectively, P<0.001; odds ratio 2.0 [95% CI: 1.6-2.5]). There was a positive correlation between infant weight and a positive Berlin Questionnaire. The incidence of preeclampsia was greater (odds ratio 3.9) in the pregnant patients with a positive Berlin Questionnaire as compared with the parturients with a negative Berlin Questionnaire (odds ratio 1.1). CONCLUSION Parturients are more likely to have a positive Berlin Questionnaire than non-pregnant women. This may indicate an increased likelihood of sleep disordered breathing.

The Relationship of Body Mass Index with the Incidence of Postdural Puncture Headache in Parturients.

BACKGROUND:Unintentional dural puncture is a known risk after epidural or combined spinal–epidural procedures, occurring in approximately 1% of labor epidural catheters placed in parturients with normal body habitus but may be as high as 4% in morbidly obese parturients. Anecdotal experience and limited publications suggest that an inverse relationship between body mass index (BMI) and postdural puncture headache (PDPH) may exist. We hypothesized that parturients with increased BMI have a lower incidence of PDPH than those with a lower BMI after unintentional dural puncture. METHODS:After IRB approval, we performed a retrospective cohort study by medical record review. Case logs from our institution were searched for patients with documented unintentional dural puncture during attempted neuraxial analgesia between January 1, 2004, and December 13, 2013. The primary outcome was the incidence of PDPH. The association between BMI and PDPH was assessed using binary logistic regression, and the Wilcoxon-Mann-Whitney odds and confidence intervals (CIs) for a random pair of BMI values from a PDPH subject compared with a non-PDPH subject were calculated from the area under the receiver operator characteristics curve. Classification tree analysis was used to determine the BMI cutoff value for the risk of developing a PDPH. The presence or absence of second-stage labor pushing and placement of an intrathecal catheter after unintentional dural puncture were compared in parturients with and without PDPH using the Fisher exact test. BMI groups were dichotomized at the cutoff value (low and high BMI groups). We compared the incidence of a PDPH between high and low BMI groups using the Fisher exact test after controlling for pushing during labor and placement of an intrathecal catheter at the time of unintentional dural puncture. Secondary analysis evaluated the highest reported numeric rating of pain scores for headache and the need for an epidural blood patch between BMI groups. RESULTS:Unintentional dural puncture was identified in 518 (0.53%) patients (95% CI, 0.48%–0.58%). The overall incidence of PDPH after unintentional dural puncture was 51% (95% CI, 46%–55%). The Wilcoxon-Mann-Whitney odds for a random pair of BMI values from a PDPH subject compared with a non-PDPH subject was 0.74 (95% CI, 0.60–0.90, P = 0.001). The odds ratio for developing a PDPH in women who pushed during delivery was 2.4 (95% CI, 1.2–3.9, P = 0.001) compared with women who did not push. Classification tree analysis identified a BMI cutoff value of 31.5 kg/m2 for prediction of a PDPH. The incidence of PDPH in parturients with a BMI ≥31.5 kg/m2 (39%) was lower than in parturients with a BMI <31.5 kg/m2 (56%; difference −17%; 95% CI, −7% to −26%, P = 0.0004). The odds ratio for a PDPH in the high BMI compared with the low BMI group was 0.36 (95% CI, 0.14–0.92, P = 0.04) in parturients who pushed during labor and 0.62 (95% CI, 0.41–0.97, P = 0. 04) in parturients who did not push. After the unintentional dural puncture, 112 (22%) parturients had an intrathecal catheter placed. The incidence of PDPH in parturients with an intrathecal catheter was 59% (95% CI, 49%–68%) compared with 48% (95% CI, 43%–54%) in women with an epidural catheter (P = 0.06). Median (interquartile range) headache severity (0–10 verbal rating scale) was 8 (6–9) and did not differ between parturients in the high versus low BMI groups (P = 0.61). The rate of epidural blood patch administration for PDPH treatment was similar in BMI groups (difference −12%; 95% CI, 4 to −27, P = 0.13). CONCLUSIONS:The findings are consistent with previous reports of decreased PDPH incidence after unintentional dural puncture in parturients with an increased BMI, even after controlling for pushing during labor. Severity of headache and need for epidural blood patch treatment were similar in low and high BMI groups.

Low-dose ketamine with multimodal postcesarean delivery analgesia: a randomized controlled trial.

BACKGROUND Ketamine at subanesthetic doses has analgesic properties that have been shown to reduce postoperative pain and morphine consumption. We hypothesized that intravenous ketamine 10mg administered during spinal anesthesia for cesarean delivery, in addition to intrathecal morphine and intravenous ketorolac, would decrease the incidence of breakthrough pain and need for supplemental postoperative analgesia. METHODS Using a randomized double-blind placebo-controlled design, healthy women scheduled for cesarean delivery receiving hyperbaric spinal bupivacaine, fentanyl and morphine were randomized to intravenous ketamine 10mg or saline following delivery. Postoperative analgesia included scheduled ketorolac and acetaminophen/hydrocodone tablets as needed for breakthrough pain. The primary outcome was the incidence of breakthrough pain in the first 24h. Secondary outcomes included the number of acetaminophen/hydrocodone tablets administered and numeric rating scale for pain (0-10). RESULTS Group characteristics did not differ. There was no difference in the incidence of breakthrough pain (ketamine 75% VS. saline 74%, P=0.86). There was no difference in 24-h or 72-h use of supplemental acetaminophen/hydrocodone tablets between groups. Pain scores in the first 24h were similar, but lower in the ketamine compared to the saline group 2weeks postpartum (difference -0.6, 95% CI -1.1 to -0.9). CONCLUSIONS We found no additional postoperative analgesic benefit of low-dose ketamine during cesarean delivery in patients who received intrathecal morphine and intravenous ketorolac. Subjects who received ketamine reported lower pain scores 2weeks postpartum.

The effect of intravenous magnesium therapy on the duration of intrathecal fentanyl labor analgesia

BACKGROUND Magnesium has been reported to augment the analgesic effects of opioids when co-administered into the cerebrospinal fluid. The purpose of this study was to determine the influence of intravenous magnesium therapy administered for preeclampsia on the duration of intrathecal fentanyl analgesia for labor. METHODS Thirty-four nulliparous parturients having labor induced for preeclampsia and receiving intravenous magnesium therapy were recruited. Thirty-four nulliparous patients having labor induced for elective or medical reasons were recruited as controls. At request for analgesia, baseline serum magnesium levels were obtained and combined spinal-epidural analgesia was initiated with intrathecal fentanyl 25μg. Before injection of fentanyl, a sample of cerebrospinal fluid was obtained for magnesium assay. An epidural catheter was sited but no additional medications were administered until the second request for analgesia. The primary outcome was duration of intrathecal fentanyl analgesia. RESULTS There was no difference in the median duration of analgesia between the magnesium [79min (95% CI 76 to 82)] and control groups [69min (95% CI 56 to 82)] (difference between medians: 10min (95% CI -4 to 21min; P=0.16). There was neither a relationship between the serum and cerebrospinal fluid magnesium concentrations nor the cerebrospinal magnesium concentration and duration of intrathecal fentanyl analgesia. CONCLUSIONS Intravenous magnesium therapy at doses typically used for seizure prophylaxis in preeclampsia did not influence the duration of intrathecal fentanyl labor analgesia. However, this study may have been underpowered to detect a difference and future study is warranted.

A randomised comparison of bolus phenylephrine and ephedrine for the management of spinal hypotension in patients with severe preeclampsia and fetal compromise

BACKGROUND Studies in healthy patients undergoing elective caesarean delivery show that, compared with phenylephrine, ephedrine used to treat spinal hypotension is associated with increased fetal acidosis. This has not been investigated prospectively in women with severe preeclampsia. METHODS Patients with preeclampsia requiring caesarean delivery for a non-reassuring fetal heart tracing were randomised to receive either bolus ephedrine (7.5-15mg) or phenylephrine (50-100µg), to treat spinal hypotension. The primary outcome was umbilical arterial base excess. Secondary outcomes were umbilical arterial and venous pH and lactate concentration, venous base excess, and Apgar scores. RESULTS Among 133 women, 64 who required vasopressor treatment were randomised into groups of 32 with similar patient characteristics. Pre-delivery blood pressure changes were similar. There was no difference in mean [standard deviation] umbilical artery base excess (-4.9 [3.7] vs -6.0 [4.6] mmol/L for ephedrine and phenylephrine respectively; P=0.29). Mean umbilical arterial and venous pH and lactate concentrations did not significantly differ between groups (7.25 [0.08] vs 7.22 [0.10], 7.28 [0.07] vs 7.27 [0.10], and 3.41 [2.18] vs 3.28 [2.44] mmol/L respectively). Umbilical venous oxygen tension was higher in the ephedrine group (2.8 [0.7] vs 2.4 [0.62]) kPa, P=0.02). There was no difference in 1- or 5-min Apgar scores, numbers of neonates with 1-min Apgar scores <7 or with a pH <7.2. CONCLUSIONS In patients with severe preeclampsia and fetal compromise, fetal acid-base status is independent of the use of bolus ephedrine versus phenylephrine to treat spinal hypotension.

The Effect of Prophylactic Phenylephrine and Ephedrine Infusions on Umbilical Artery Blood ph in Women With Preeclampsia Undergoing Cesarean Delivery With Spinal Anesthesia: A Randomized, Double-blind Trial

BACKGROUND: Spinal anesthesia for cesarean delivery is associated with a high incidence of hypotension. Phenylephrine results in higher umbilical artery pH than ephedrine when used to prevent or treat hypotension in healthy women. We hypothesized that phenylephrine compared to ephedrine would result in higher umbilical artery pH in women with preeclampsia undergoing cesarean delivery with spinal anesthesia. METHODS: This study was a randomized double-blind clinical trial. Nonlaboring women with preeclampsia scheduled for cesarean delivery with spinal anesthesia at Prentice Women’s Hospital of Northwestern Medicine were randomized to receive prophylactic infusions of phenylephrine or ephedrine titrated to maintain systolic blood pressure >80% of baseline. Spinal anesthesia consisted of hyperbaric 0.75% bupivacaine 12 mg, fentanyl 15 µg, and morphine 150 µg. The primary outcome was umbilical arterial blood pH and the secondary outcome was umbilical artery base excess. RESULTS: One hundred ten women were enrolled in the study and 54 per group were included in the analysis. There were 74 and 72 infants delivered in the ephedrine and phenylephrine groups, respectively. The phenylephrine:ephedrine ratio for umbilical artery pH was 1.002 (95% confidence interval [CI], 0.997–1.007). Mean [standard deviation] umbilical artery pH was not different between the ephedrine 7.20 [0.10] and phenylephrine 7.22 [0.07] groups (mean difference −0.02, 95% CI of the difference −0.06 to 0.07; P = .38). Median (first, third quartiles) umbilical artery base excess was −3.4 mEq/L (−5.7 to −2.0 mEq/L) in the ephedrine group and −2.8 mEq/L (−4.6 to −2.2mEq/L) in the phenylephrine group (difference −0.6 mEq/L, 95% CI of the difference −1.6 to 0.3 mEq/L; P = .10). When adjusted for gestational age and infant gender, umbilical artery pH did not differ between groups. There were also no differences in the umbilical artery pH stratified by magnesium therapy or by the severity of preeclampsia. CONCLUSIONS: We were unable to demonstrate a beneficial effect of phenylephrine on umbilical artery pH compared with ephedrine. Our findings suggest that phenylephrine may not have a clinically important advantage compared with ephedrine with regard to improved neonatal acid-base status when used to prevent spinal anesthesia–induced hypotension in women with preeclampsia undergoing cesarean delivery.