Neuraxial labor analgesia: a focused narrative review of the 2017 literature.

PURPOSE OF REVIEW: Neuraxial labor analgesia remains the most effective and one of the most commonly utilized methods for pain relief during labor. This narrative review article is a summary of the literature published in 2017 on neuraxial analgesia for labor. RECENT FINDINGS: From a total of 41 identified articles, 13 were included in the review. The topics have been structured into three categories: initiation of neuraxial analgesia, maintenance of neuraxial analgesia, and neuraxial analgesia and obstetric outcomes. Maintenance regimens, such as program intermittent epidural bolus (PIEB) techniques, remain a focus of extensive research with the potential to optimize analgesia for each individual patient. In a similar way, the dural puncture epidural technique could improve the quality of labor analgesia with fewer side effects compared with standard epidural and combined spinal epidural (CSE) techniques. Finally, the increased use of modern technology using portable ultrasound devices with automated imaging software to facilitate epidural catheter placement may offer potential advantages to the obstetric anesthesiologist, especially when dealing with technically difficult cases. SUMMARY: Recent advances, as well as refinements, of current neuraxial analgesia techniques could improve women's experience of labor.

A comparison of minimum local anesthetic volumes and doses of epidural bupivacaine (0.125% w/v and 0.25% w/v) for analgesia in labor.

BACKGROUND: In this study we sought to determine and compare the minimum local anesthetic volumes (MLAV) and doses (MLAD) of two concentrations of bupivacaine for epidural pain relief in labor, and to quantify the effect on dose. METHODS: Eighty women were randomized in a double-blind manner to receive a first bolus of either plain bupivacaine 0.125% (w/v) or 0.25% (w/v). The arbitrary starting volume was 15 mL. Subsequent volumes were decided by sequential allocation according to analgesic efficacy. A visual analog pain score < or =10 (0-100) within 30 min, indicated effective analgesia. The next woman received a decrement of 2 mL. A failure of the visual analog pain score to reach < or =10 was followed by a 2 mL increment for the next woman. RESULTS: Using the formula of Dixon and Massey, MLAV and MLAD, with 95% confidence intervals (CI) were calculated for each concentration. MLAV was 13.6 mL (95% CI 12.4-14.8), with bupivacaine 0.125% (w/v), and 9.2 mL (95% CI 6.9-11.5) with bupivacaine 0.25% (w/v). The difference was highly significant (P = 0.002). MLAD for these volumes were 17.0 mg (95% CI 15.5-18.5), and 23.1 mg (17.2-28.9), respectively (P = 0.045). CONCLUSIONS: Bupivacaine 0.125% (w/v) when compared with 0.25% (w/v) produced equivalent analgesia with a 50% increase in volume, but with a 25% reduction in dose. Any reduction in dose, without loss of efficacy, reduces risk of toxicity and improves safety.

Postoperative epidural analgesia in obese patients undergoing liver resection surgery.

AIM: To investigate the relation of body mass index (BMI) with postoperative pain scores and volume of local anaesthetic (LA) administered epidurally in patients undergoing liver resection surgery. METHODS: Retrospective data from 167 patients who had epidural analgesia (EA) for liver resection surgery were analysed: 123 with BMI < 30kgm-2 and 44 with BMI > 30kgm-2. RESULTS: Total volume of intraoperative bolus of epidural analgesia (EA) was not different between the BMI more than 30 kgm-2 and BMI less than 30 kgm-2 groups (p less 0.05). Mean rate of infusion (8.2±2.7 ml/h vs. 7.9±1.9 ml/h, p=0.0018), pain scores immediately after extubation of the trachea (0.91±0.9 vs. 0.55±0.7, p=0.017) and that before removal of epidural catheter (0.7±0.55 vs. 0.7±0.95, p=0.015) were higher in the BMI > 30kgm-2 group when compared with the BMI ≤ 30kgm-2 group. However, there was no significant difference between the numbers of segments blocked. CONCLUSION: The patients with BMI more than 30 kgm-2 undergoing liver resection experienced more postoperative pain on the day of surgery and before epidural catheter removal than patients with BMI less than 30 kgm-2, despite a higher rate of epidural infusion. Further studies are necessary to confirm these findings in order to determine adequate local anaesthetic dosing for thoracic epidural analgesia in obese patients.

Uterine clostridial myonecrosis after thermal balloon endometrial ablation.

BACKGROUND: We present a case of a patient who had development of uterine clostridial myonecrosis after elective thermal balloon endometrial ablation in the absence of identifiable risk factors. CASE: A 51-year-old woman underwent uneventful thermal balloon endometrial ablation for the treatment of menorrhagia. The next day, she presented with acute inflammatory syndrome, severe intravascular hemolysis, and acute kidney injury. The blood cultures and the high vaginal swab showed moderate growth of Clostridium species. A total abdominal hysterectomy and bilateral salpingo-oophorectomy were performed. Her postoperative course was uneventful, and renal function gradually recovered. CONCLUSION: Clostridial myonecrosis after uncomplicated surgery, although rare, should be considered in the differential diagnosis of the acutely septic patient with massive hemolysis, regardless of the presence of patient's risk factors.

Three different approaches to Transversus abdominis planeblock: a cadaveric study.

AIM: The transversus abdominis plane (TAP) block is a new technique for providing analgesia to the anterior abdominal wall. There is ongoing debate regarding access point for TAP block. The aim of this cadaveric study was to compare the spread of 40 mL of dye using three different approaches to TAP: subcostal , via the mid-axillary and via the lumbar triangle of Petit (LTOP). METHODS: Injection of black dye into the TAP was performed for each hemi-abdominal wall of 13 embalmed human cadavers by using 3 different access points: subcostal (9 hemi-abdomens), mid-axillary (9) and LTOP (8). This was followed by dissection to determine the extent of dye spread and nerve involvement in the dye injection. The shapes of the dye were traced onto clear plastic, which was then photographed. These digital photographs were loaded into the mathematical software programme Matlab, and the outline of the dye spread was digitised using a piecewise cubic spline, enabling the shapes to be plotted on a graph and the areas to be calculated. RESULTS: The area of the dye spread for subcostal, mid-axillary and LTOP was 85.1 (T7-L1), 58.9 (T10-L1) and 77.9 cm² (T10-L1), respectively. There was statistically significant difference between area of dye spread between subcostal and mid-axillary approach (p<0.01). CONCLUSIONS: This dye injection study in a cadaver model indicates that subcostal approach is associated with a larger area of spread of dye than the mid-axillary approach. Dye injected through subcostal, mid-axillary and LTOP approaches demonstrated different nerve involvement.