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.

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.