J.C. Carvalho

ED95 of phenylephrine to prevent spinal-induced hypotension and/or nausea at elective cesarean delivery

BACKGROUND The purpose of this trial was to determine the 95% effective dose (ED95) of phenylephrine by intermittent i.v. bolus, to prevent spinal-induced hypotension and/or nausea at elective cesarean delivery. METHODS The study was conducted in a double-blinded fashion in 50 patients undergoing elective cesarean delivery under spinal anesthesia. The dose of phenylephrine was determined using up-down sequential allocation, modified by a variation of the Narayana rule. Systolic pressure and heart rate were assessed every minute until uterine incision. The first patient was assigned a 40-microg dose, and the dose to subsequent patients varied by 10-microg increments or decrements. An adequate response was defined as absence of hypotension (systolic pressure <80% of baseline) and nausea. The study solution was given immediately after spinal administration, without prior pressure measurement, and thereafter when the systolic pressure was <or=control values. fell below baseline. The ED95 was determined by a logistic model with non-log-transformed doses, using Firths penalized maximum likelihood method with 95% confidence intervals based on penalized profile likelihood. RESULTS The ED95 of phenylephrine was estimated as 159 microg (95% confidence interval: 122-371 microg), although the largest dose given in the study was only 120 microg. Hypertension (systolic blood pressure >120% of baseline) was observed in 14 cases, immediately after intrathecal injection and prophylactic phenylephrine administration in all cases. CONCLUSION The ED95 of phenylephrine, administered as intermittent boluses to prevent pre-delivery spinal-induced hypotension and/or nausea at elective cesarean delivery, is at least 122 microg (lower limit of the confidence interval). The safety of this dose warrants further studies.

Breastfeeding success rate after vaginal delivery can be high despite the use of epidural fentanyl: an observational cohort study

BACKGROUND Epidural labor analgesia inclusive of high-dose fentanyl has been thought to affect breastfeeding in multiparous patients. In our experience, this effect is not as significant as quoted in the literature. This study was designed to evaluate breastfeeding success in women receiving epidural analgesia with fentanyl-containing solutions at our institution. METHODS Term multiparous women who received epidural analgesia for labor, had previously breastfed, and who intended to breastfeed, were recruited. Baseline demographics, as well as detailed epidural, obstetric and neonatal data, were collected. Epidural analgesia was achieved with a mixture of bupivacaine and fentanyl. Subjects were telephoned both 1 and 6 weeks after delivery, and a breastfeeding questionnaire was completed. Our primary outcome was breastfeeding cessation at 6 weeks. RESULTS One hundred and five women were recruited, with 18 exclusions. The median cumulative epidural fentanyl dose was 151.4 microg (30-570 microg). No neonates developed complications attributable to labor analgesia. Four women stopped breastfeeding because of issues related to the baby (4.6%); only one of them received a fentanyl dose >150 microg. The breastfeeding success rate was therefore >95%. The women had a median maternity leave of 12 months, and 69% received post-partum lactation support. CONCLUSIONS The incidence of successful breastfeeding in multiparous women who undergo vaginal delivery with epidural analgesia inclusive of fentanyl is much greater at our institution than previously reported in the literature. This may be due to favorable conditions such as time off work and post-natal support.

Oxytocin–ergometrine co-administration does not reduce blood loss at caesarean delivery for labour arrest*

Objective  To determine if intravenous infusion of a combination of oxytocin and ergometrine maleate is better than oxytocin alone to decrease blood loss at caesarean delivery for labour arrest.

Monitoramento não invasivo baseado na biorreatância revela instabilidade hemodinâmica significativa durante cesárea eletiva sob raquianestesia

JUSTIFICATIVA Y OBJETIVOS: La monitorizacion de la presion arterial ofrece una comprension limitada de las consecuencias hemodinamicas de la raquianestesia para la cesarea. El objetivo de este estudio fue evaluar, con la ayuda del monitor de debito cardiaco no invasivo y con base en la biorreactancia, las alteraciones hemodinamicas durante la cesarea electiva bajo raquianestesia, en la cual bolos intermitentes de fenilefrina fueron utilizados para prevenir y tratar la hipotension. METODOS: Este estudio observacional fue realizado posterior a la aprobacion de la comision de etica en investigacion y de la firma del consentimiento informado. Se evaluaron los pacientes sanos con cesarea electiva programada bajo raquianestesia. Bolos intermitentes de fenilefrina fueron administrados para mantener la presion arterial sistolica en los niveles basales, y las pacientes fueron evaluadas con la ayuda del monitor de debito cardiaco no invasivo con base en la biorreactancia. Los datos hemodinamicos se recopilaron continuamente en el momento basal y durante los periodos postraquianestesia y despues del nacimiento del feto. Los datos se analizaron usando ANOVA para modelos mixtos, y un p < 0,05 fue considerado significativo. RESULTADOS: La presion arterial sistolica se mantuvo entre 79,2 (14,2) y 105,9 (10,0) por ciento de los valores basales durante el periodo postraquianestesia, y 78,4 (11,13) y 100,9 (10,7) por ciento de los valores basales en el periodo postparto promedio ± de. Las fluctuaciones significativas se observaron en la presion arterial sistolica, en la frecuencia cardiaca y en el debito cardiaco en el periodo postparto. CONCLUSIONES: Un nuevo monitor no invasivo, con base en la biorreactancia, revelo fluctuaciones hemodinamicas significativas durante la cesarea bajo la raquianestesia, pese a los intentos de mantener la presion arterial a niveles basales con bolos intermitentes de fenilefrina.

Optimal hand washing technique to minimize bacterial contamination before neuraxial anesthesia: a randomized control trial

INTRODUCTION Infectious complications related to neuraxial anesthesia may result in adverse outcomes. There are no best practice guidelines regarding hand-sanitizing measures specifically for these procedures. The objective of this study was to compare the growth of microbial organisms on the operators forearm between five common techniques of hand washing for labor epidurals. METHODS In this single blind randomized controlled trial, all anesthesiologists performing labor epidurals in a tertiary care hospital were randomized into five study groups: hand washing with alcohol gel only up to elbows (Group A); hand washing with soap up to elbows, sterile towel to dry, followed by alcohol gel (Group B); hand washing with soap up to elbows, non-sterile towel to dry, followed by alcohol gel (Group C); hand washing with soap up to elbows, non-sterile towel to dry (Group D) or hand washing with soap up to elbows, sterile towel to dry (Group E). The number of colonies for each specimen/rate per 100 specimens on one or both arms per group was measured. RESULTS The incidence of colonization was 2.5, 23.0, 18.5, 114.5, and 53.0 in Groups A, B, C, D and E, respectively. Compared to Group A, the odds ratio of bacterial growth for Group B was 1.52 (P=0.519), Group C 5.44 (P=0.003), Group D 13.82 (P<0.001), and Group E 8.65 (P<0.001). CONCLUSION Alcohol-based antiseptic solutions are superior in terms of reducing the incidence of colonization. The results will enable us to develop guidelines to standardize and improve hand-sanitizing practices among epidural practitioners.

A Perioperative Course of Gabapentin Does Not Produce a Clinically Meaningful Improvement in Analgesia After Cesarean Delivery

Gabapentin is an analgesic that has proven itself to be beneficial perioperatively for several surgeries, some of which, such as abdominal hysterectomy, are similar to cesarean delivery. There is also extensive information on this drug from its use as an anticonvulsant, in which it has been shown to be safe for use during pregnancy and breastfeeding. But while there have been studies evaluating its efficacy for pain management following cesarean delivery, studies evaluating use of a single preoperative dose for pain management following cesarean delivery have not produced definitive results. The authors of this trial sought to test the analgesic effect of gabapentin when given perioperatively for cesarean delivery. This single-center superiority trial was randomized, double-blinded, placebo-controlled, and featured parallel groups. Women were included in the study if they were 18 to 55 years old and were scheduled for elective cesarean delivery of a singleton fetus under spinal anesthesia. A total of 197 participants were randomized to receive either a perioperative oral course of gabapentin (600mg administered preoperatively followed by 200mg every 8 h for 48 h) or a placebo. Pain was measured 24 hours after surgery and again at 48 hours, both at rest and during movement using a visual analog scale (VAS, 0 to 100mm). The primary outcome was the level of pain experienced during movement at the 24-hour mark. Other outcomes included neonatal outcomes, opioid consumption, patient satisfaction measured with a VAS score, adverse effects, and persistent pain. The experimental group and the control group shared similar baseline characteristics. The VAS pain scores in the gabapentin group showed a small but statistically significant decrease for pain during movement at 24 hours compared with the control group [40mm (36 to 45) vs. 47mm (42 to 51); difference, 7mm ( 13 to 0); P=0.047]. At the 24-hour mark more patients in the experimental group were sedated (55% vs. 39%, P=0.026), but they also reported a higher VAS score for patient satisfaction (87 vs. 77mm, P=0.003). The findings of this trial show that an oral course of gabapentin in which 600mg was administered preoperatively, followed by 200mg every 8 hours for the next 48 hours did slightly reduce pain while also increasing satisfaction in the first 24 hours after cesarean delivery. However, it was also associated with an increased rate of sedation, and it is questionable whether these results are clinically significant. Therefore, gabapentin should not become a standard addition to the analgesic regimen for cesarean delivery, but it could be useful in any subgroups of women who might be at risk for experiencing a higher level of pain following the procedure.

Lumbar Dural Sac Dimensions Determined by Ultrasound Helps Predict Sensory Block Extent During Combined Spinal-Epidural Analgesia for Labor

Background and Objectives: The lumbosacral cerebrospinal fluid volume is a major determinant of the intrathecal spread of local anesthetics. Ultrasound imaging of the lumbar spine allows measurement of dural sac dimensions, which may potentially be used as a surrogate of cerebrospinal fluid volume. The purpose of this study was to investigate the correlation between lumbar dural sac diameter, dural sac length (DSL), and dural sac volume (DSV), measured by ultrasound, and the intrathecal spread of isobaric bupivacaine during combined spinal-epidural (CSE) analgesia for labor. Methods: We examined 41 women with singleton pregnancies requesting neuraxial analgesia for labor. Using a 5-2YMHz curved-array ultrasound probe in the paramedian sagittal plane, we measured the dural sac width at each lumbar interspace and the DSL from L1-2 to L5-S1 interspace and calculated the dural sac volume (DSV). Following CSE block with 0.25% isobaric bupivacaine 1.75 mg and fentanyl 15Kg, peak sensory levels (PSLs) were recorded using ice, cotton, and pinprick. Statistical correlation coefficients between dural sac dimensions and PSLs were assessed by Spearman rank correlation. In addition, multiple linear regression models were used to select important predictors of PSLs. Results: There was a moderate correlation between DSL and PSL to ice (Q = j0.62; P G 0.0005) and to pinprick (Q = j0.52; P = 0.017). Similarly, there was a moderate correlation between DSVand PSL to ice (Q =j0.56; P = 0.004) and to pinprick (Q =j0.61; P G 0.0008). Neither the DSL nor DSV correlated with PSL to cotton. Multiple linear regression analysis revealed that DSL, weight, and body mass index contributed to PSLs. Conclusions: The length of the lumbar spine determined by ultrasound, rather than the lumbar spine volume, combined with the weight or body mass index of the subject, is of particular value in predicting the intrathecal spread of isobaric bupivacaine during CSE analgesia for labor.

Ultrasound Simulation of Internal Jugular Vein Cannulation in Pregnant and Nonpregnant Women

Central venous cannulation (CVC) can occur via the internal jugular vein (IJV), with localization either by anatomical landmarks or palpation of the carotid artery (CA). CVC carries significant risk and is uncommonly performed in parturients. However, it may be necessary in high-risk and critically ill women. Pregnancy alters the neck anatomy, making CVC placement more difficult in parturients compared to nonpregnant women. Whether pregnancy affects the relative position of the IJV and CA is unknown. An emerging alternative method for vessel localization is ultrasound imaging, which allows visualization of the vessels during the procedure. This study of the success rate of IJV cannulation and rate of carotid puncture in pregnant versus nonpregnant women used ultrasound to confirm the success or failure rates by “blind” approaches and to study the relative positions of the IJV and the CA in the 2 groups of women. Term parturients in early labor or who were scheduled for elective cesarean section were recruited at admission. At the same time, nonpregnant volunteers (hospital staff and inpatients) were recruited as controls. Subjects were aged 18 to 40 years. Exclusion criteria included visibly abnormal neck anatomy, previous neck trauma, or prior cannulation of neck vessels. Women were positioned supine with their heads turned 35 degrees to the left. Both central landmark and palpatory approaches were studied, with one experienced investigator marking optimal needle insertion points, carrying out CVC simulation, and recording ease of assessing landmarks in all attempts. Two-dimensional ultrasound images of the neck were obtained with a 15 to 10MHz linear probe placed on each pre-marked insertion point so as to simulate placement of a syringe and needle for CVC. When the image quality was adequate, the built-in vertical cursor that delineates the path of a needle was placed in the image and a second investigator determined the outcome of each attempt. It was considered “successful” if the cursor intersected the lumen of the IJV without intersecting the CA; if the CA was intersected, it was a “carotid puncture.” Any other outcome was a “missed attempt.” During the 12 month study period, 161 women agreed to participate: 99 parturients and 62 nonpregnant women. Pregnant women were older and heavier and identification of landmarks (P=0.012) was more difficult than in controls. Rates of successful IJV localization, carotid punctures, and missed attempts, however, did not differ significantly between the groups. The rates of successful IJV punctures in the central landmark approach were 62.6% among pregnant women, versus 72.6% in nonpregnant women. CA puncture rates were 19.2%, versus 9.7%, respectively. In the palpatory approach, rates of successful IJV punctures were 35.4%, pregnant, versus 41.9%, nonpregnant; CA punctures were 6.1%, versus 3.2%, for pregnant and nonpregnant subjects, respectively. More than half of the attempts with the palpatory approach were missed in both pregnant and nonpregnant women. There was more overlapping between the IJV and the CA in pregnant women using both the central landmark (P=0.034) and palpatory (P<0.001) approaches. These results confirmed that identification of anatomical landmarks is more difficult and the degree of overlap of IJV and CA is higher in pregnant women than in nonpregnant women, which may be due in part to the higher weight of pregnant women. Cannulation success is attained more often in the central landmark approach than by palpation. The authors concluded that the findings support the use of real-time ultrasound for CVC in pregnant women as it may reduce the risk of accidental carotid punctures.

Anesthesiologistsʼ Learning Curves for Ultrasound Assessment of the Lumbar Spine

Background and objectives Ultrasound assessment of the lumbar spine to facilitate neuraxial anesthesia has recently received much attention. The transfer of knowledge pertaining to this skill has never been studied. The purpose of this study was to determine the amount of teaching needed to achieve competence in spinal