The effect of high-dose versus low-dose epidural fentanyl on gastric emptying in nonfasted parturients: A double-blinded randomised controlled trial.

BACKGROUND: Epidural fentanyl doses above 100 µg have been shown, using the paracetamol absorption test, to reduce gastric emptying in fasted labouring women. OBJECTIVE: To investigate the effect of fentanyl dose on gastric emptying in nonfasted labouring women using gastric ultrasonography. DESIGN: A double-blinded randomised controlled study. SETTING: A tertiary medical centre in Tel Aviv, Israel between 30 July 2020 and 11 October 2020. PATIENTS: Eighty labouring women with cervical dilation 5 cm or less, at least 18 years age, at least 37 weeks gestation with a singleton pregnancy and cephalad foetus. INTERVENTIONS: Women randomised to high (>100 µg) or low (<100 µg) cumulative epidural fentanyl had ultrasound gastric content assessment, measuring antral cross-sectional area (CSA) at epidural placement and 2 h thereafter (T2  h). MAIN OUTCOME MEASURES: The primary outcome was CSA at T2  h comparing high-dose versus low-dose fentanyl. Secondary outcomes included change in CSA between baseline and T2  h. Sub-group analysis compared stomach content at T2  h according to baseline stomach content, empty (CSA <381 mm2) or full (CSA ≥381 mm2), and high-dose versus low-dose fentanyl. RESULTS: Data from 80 women were analysed; 63 had empty and 17 had full stomach at baseline. There was no significant difference in CSA at T2  h between high-dose, mean 335 ±â€ŠSD 133 mm2, versus low-dose fentanyl, mean 335 ±â€ŠSD 172 mm2, P = 0.991. Change in CSA baseline to T2  h was 46 ±â€ŠSD 149 mm2 for high and 49 ±â€ŠSD 163 mm2 for low-dose group, P = 0.931. The subgroup analysis according to baseline stomach content showed no statistically significant differences in CSA at T2  h. CONCLUSION: The CSA at T2  h was similar for women who received high-dose versus low-dose epidural fentanyl, measured by ultrasound, in our nonfasted labouring cohort. TRIAL REGISTRATION: Clinicaltrials.gov number: NCT04202887.

Prospective observational investigation of body habitus measurements and relationship to epidural depth in term pregnant women.

BACKGROUND: High body mass index (BMI) can predict difficult neuraxial block; however, fat distribution may also be important. The primary study aim was to identify body habitus and fat distribution measurements that correlated with ultrasound measured epidural depth. We hypothesized that measurements such as midarm and subscapular fatpad thicknesses and length of cervical spine may correlate better with ultrasound measured epidural depth than a global measure of BMI. METHODS: Prospective IRB approved study of term pregnant women requiring neuraxial block. We measured height, weight (BMI, kg/m2 ), subscapular, midarm fatpad thickness (digital caliper, mm), vertebral column length (C7 to sacral hiatus, cm) and epidural depth (ultrasound, mm). Four experts assessed photographs to assign anticipated difficult neuraxial block in sitting and lateral positions (5-point Likert scale, 1 = very easy, 5 = very difficult). RESULTS: In all, 131 women completed body habitus measurements. Measured mean (standard deviation) BMI was 30.3 (5.4) kg/m2 . Measured BMI, subscapular fatpad and midarm fatpad thickness were significantly correlated with ultrasound depth to epidural space (R2 0.733, 0.626 and 0.633, respectively, P < .0001) but vertebral column length was not. The experts had a high level of agreement (Cronbach's alpha >0.7) for assessment of anticipated difficult block in the sitting and lateral positions; however, anticipated difficult block was not correlated with epidural depth measured by ultrasound for sitting position, R2  = -0.015, P = .87; and lateral position, R2  = -0.087, P = .33. CONCLUSIONS: Measurements of body habitus and fat distribution were no better than measured BMI to anticipate greater ultrasound measured depth to epidural space. Clinical trial number: Non-interventional observational study, not registered.

Prophylactic phenylephrine infusion versus treatment with vasopressor bolus as needed during non-urgent cesarean delivery and neonatal acidemia: a retrospective cohort study (2016-2021).

INTRODUCTION: Prophylactic vasopressor administration reduces spinal hypotension during cesarean delivery, however the effects of vasopressor administration on neonatal acidemia remain uncertain. We examined the occurrence of neonatal acidemia in the setting of non-urgent cesarean delivery and compared outcomes between cases receiving prophylactic phenylephrine infusion versus cases treated with boluses of phenylephrine. METHODS: Retrospective cohort study with ethical approval, comparing non-urgent cesarean delivery cases performed under spinal anesthesia (2016 to 2021), receiving either prophylactic phenylephrine infusion or boluses as needed. Data were collected from anesthesia and labor ward electronic medical records. Records with missing pH or missing blood pressure data were excluded. The independent variable was prophylactic phenylephrine administration, a strategy implemented following international recommendations in 2018. The main outcome was neonatal acidemia, defined as umbilical artery pH < 7.1. The secondary outcome was maternal hypotension, defined as at least one systolic blood pressure (SBP) measurement below 100 mmHg or below 80% baseline. RESULTS: A total of 4392 patients were included in the final analysis; 1318 (30.0%) received prophylactic phenylephrine infusion. Neonatal acidemia (umbilical artery pH < 7.1) occurred in 28 (2.1%) cases receiving prophylactic phenylephrine versus 50 (1.6%) treated with boluses as needed (p = 0.188). Prophylactic phenylephrine infusion was not associated with occurrence of neonatal acidemia (aOR 0.83; 95% CI 0.52 to 1.33, p = 0.435). Prophylactic phenylephrine infusion was associated with a reduced spinal hypotension rate when defined as SBP < 100 mmHg (OR 0.47; 95% CI 0.37 to 0.57; p < 0.001), with similar results when hypotension was defined as a drop below 80% or 90% of baseline SBP. CONCLUSION: In this pragmatic study, prophylactic phenylephrine infusion was associated with a reduction in maternal spinal hypotension, but not reduced neonatal acidemia.

Rate of difficult intubation during caesarean delivery: A single centre before/after standardised airway management implementation study.

BACKGROUND: The use of general anaesthesia (GA) for caesarean delivery (CD) introduces the risk of both difficult and failed intubation. Various strategies may be utilised to reduce this risk; however, not all are supported by evidence. We analysed the rate of difficult intubation following implementation of three recommendations specific to airway management in CD. METHODS: This was a retrospective single-center study of CD cases performed under GA at a tertiary care center between January 2013 and December 2022. Cases with GA induced after delivery or with incomplete airway management records were not included in the analysis. We compared outcomes for cases before (2013-2018) versus after (2019-2022) implementation of three specific recommendations: (1) video laryngoscopy (VL) for the first intubation attempt; (2) the presence of a second anesthetist; (3) use of endotracheal tube size 6.5 mm. The primary outcome was difficult intubation, defined as a composite variable (> 1 intubation attempt, use of a rescue device, SpO2 < 90%). We conducted univariable and adjusted analyses of plausible variables associated with difficult intubation, including age, body mass index, predicted difficult airway, and each of three recommendations. RESULTS: We identified 1462 cases, 922 before and 540 after implementation. The frequency of difficult intubation was similar with 239 (25.9%) before versus 135 (25.0%) after implementation (p = 0.71; 95% CI -0.03 to 0.05). The recommendations were not associated with a decreased likelihood of difficult intubation in the univariable and adjusted models. Adoption of all three recommendations was significantly more frequent in the post-implementation period. CONCLUSION: Implementation of standardised airway management recommendations had no significant impact on difficult intubation rate, though adoption of all three recommendations was not universal.

Effects of methylene blue and volatile anesthetics on survival in a murine hemorrhage resuscitation model.

BACKGROUND: Hemorrhage is a frequent cause of morbidity and mortality, possibly complicated by volatile anesthetics administered during surgical emergencies. Because methylene blue (MB) was suggested to reduce bleeding, we reasoned that it may improve resuscitation. We used a rat model of controlled and uncontrolled hemorrhage with fluid resuscitation, aiming at high versus low mean arterial pressure (MAP) to assess the role of early MB injection on survival and the effects of different anesthetics on outcome. METHODS: Wistar male rats (n = 160) were subjected to 15-minute controlled and 60-minute uncontrolled hemorrhage and received lactated Ringer's solution replacement. Four sets (four groups per set, N = 10 per group) were anesthetized with halothane, isoflurane, sevoflurane, or ketamine (KET; control). Resuscitation-targeted MAP was 80 mm Hg in two groups per set and 40 mm Hg in two groups per set: one group received MB 25 mg/kg intravenously and the other one did not receive. RESULTS: All parameters were worse in the higher target groups compared with the lower MAP target groups. MB improved variable outcomes in the treated compared with the nontreated groups, independent of the MAP or anesthesia agent: the amount of replacement volume, lung tissue xanthine oxidase activity, and rats' survival rates. Outcomes with and without MB were worse in the halothane set, followed, in ascending order, by sevoflurane, isoflurane, and KET. CONCLUSIONS: MB improved parameters and survival rates after controlled and uncontrolled hemorrhage and fluid resuscitation, even in high MAP-resuscitated rats. KET seemed to be the best anesthetic choice among the four classic agents tested. The effects of balanced anesthesia and total intravenous anesthesia in similar conditions require additional studies.