Spread of epidural analgesia following a constant pressure injection

Efficacy and safety of ketamine as an adjuvant to regional anesthesia: A systematic review and meta-analysis of randomized controlled trials

STUDY OBJECTIVE

To identify whether adding ketamine to the local anesthetics (LA) in the regional anesthesia could prolong the duration of analgesia.

DESIGN

A Systematic review and meta-analysis of randomized controlled trials.

SETTING

The major dates were obtained in the operating room and the postoperative recovery ward.

PATIENTS

A total of 1011 patients at ASA physical status I and II were included in the analysis. Procedure performed including cesarean section, orthopedic, radical mastectomy, urological or lower abdominal surgery and intracavitary brachytherapy implants insertion.

INTERVENTIONS

After an extensive search of the electronic database, patients received regional anesthesia combined or not combined general anesthesia and with or without adding ketamine to LA were included in the analysis. The regional anesthesia includes spinal anesthesia, brachial plexus block, pectoral nerve block, transversus abdominis plane block and femoral and sciatic nerve block.

MEASUREMENT

The primary outcome was the duration of analgesia. Secondary outcomes were the duration and onset time of motor and sensory block as well as the ketamine-related adverse effect. Data are expressed in mean differences in continuous data and odds ratios (OR) for dichotomous data with 95% confidence intervals. The risk of bias of the included studies was evaluated using the revised Cochrane risk of bias tool for randomized trials. The quality of evidence for each outcome was rated according to the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) Working Group system.

MAIN RESULT

Twenty randomized controlled trials were included in the analysis. When ketamine was used as an adjuvant to LA, the duration of analgesia could be prolonged(172.21 min, 95% CI, 118.20 to 226.22; P<0.00001, I2 = 98%), especially in the peripheral nerve block(366.96 min, 95% CI, 154.19 to 579.74; P = 0.0007, I2 = 98%). Secondary outcomes showed ketamine could prolong the duration of sensory block(29.12 min, 95% CI, 10.22 to 48.01; P = 0.003, I2 = 96%) but no effect on the motor block(6.94 min, 95% CI,-2.65 to 16.53;P = 0.16, I2 = 84%), the onset time of motor and sensory block (motor onset time, -1.17 min, 95% CI, -2.67 to 0.34; P = 0.13, I2 = 100%; sensory onset time, -0.33 min, 95% CI,-0.87 to 0.20; P = 0.23, I2 = 96%) as well as the ketamine-related adverse effect(OR, 1.97, 95% CI,0.93 to 4.17;P = 0.08, I2 = 57%).

CONCLUSION

This study indicates that ketamine could be an ideal adjuvant to local anesthetics regardless of the types of anesthesia. Overall, the quality of the evidence is low.

Cervical epidural analgesia in current anaesthesia practice: systematic review of its clinical utility and rationale, and technical considerations

Cervical epidural analgesia (CEA) is an analgesic technique, potentially useful for surgeries involving the upper body. Despite the inherent technical risks and systemic changes, it has been used for various surgeries. There have been no previously published systematic reviews aimed at assessing its clinical utility. This systematic review was performed to explore the perioperative benefits of CEA. The review was also aimed at identifying the rationale of its use, reported surgical indications and the method of use. We performed a literature search involving PubMed and Embase databases, to identify studies using CEA for surgical indications. Out of 467 potentially relevant articles, 73 articles were selected. Two independent investigators extracted data involving 5 randomized controlled trials, 17 observational comparative trials, and 51 case reports (series). The outcomes studied in most comparative studies were on effects of local anaesthetics and other agents, systemic effects, and feasibility of CEA. In one randomized controlled study, CEA was observed to decrease the resting pain scores after pharyngo-laryngeal surgeries. In a retrospective study, CEA was shown to decrease the cancer recurrence after pharyngeal-hypopharyngeal surgeries. The limited evidence, small studies, and the chosen outcomes do not allow for any specific recommendations based on the relative benefit or harm of CEA. Considering the potential for significant harm, in the face of better alternatives, its use must have a strong rationale mostly supported by unique patient and surgical demands. Future studies must aim to assess analgesic comparator effectiveness for clinically relevant outcomes.

Epidural pressure changes following caudal blockade: a prospective, observational study

PURPOSE

Recent case reports raise the question as to whether anesthetic agents injected into the epidural space could lead to a 'compartment syndrome' and neurovascular sequelae. Single-shot caudal epidural anesthesia has been established as a safe technique, but changes in pressure in the caudal epidural space have not been described. Our aim was to study pressure changes to provide preliminary information for future studies design.

METHODS

We prospectively measured the pressure changes in the caudal epidural space in 31 pediatric patients. The pressures were measured at loss of resistance, immediately after the bolus dose of local anesthetic (1 ml/kg), and at 15-s intervals up to 3 min.

RESULTS

The pressure at loss of resistance was 35.6 ± 27.8 mmHg. A pulsatile waveform was observed once the epidural space was accessed. The pressure after administration of the local anesthetic bolus (1 ml/kg 0.2 % ropivacaine/bupivacaine with 1:200,000 epinephrine) was 192.5 ± 93.3 mmHg. The pressure decreased to 51.5 ± 39.0 mmHg at 15 s, 26.9 ± 9.9 mmHg after 2 min, and 24.7 ± 11.7 after 3 min. The return to baseline occurred at approximately 45-60 s.

CONCLUSIONS

Following the administration of the local anesthetic into the caudal epidural space, there was a marked, but transient, increase in the pressure within the epidural space. It appears unlikely that a slow epidural catheter infusion could lead to a sustained increase in epidural pressure.

Impact of morbid obesity on epidural anesthesia complications in labor

OBJECTIVE

We sought to determine whether morbid obesity is associated with increased maternal hypotension or fetal heart rate (FHR) abnormalities after epidural anesthesia placement during labor.

STUDY DESIGN

This was a retrospective cohort study of women undergoing epidural anesthesia during labor at term from April 2008 through July 2010.

RESULTS

A total of 125 morbidly obese patients were matched for age and race with 125 normal-weight patients. Morbidly obese patients had more frequent persistent systolic (16% vs 4%, P = .003) and diastolic (49% vs 29%, P = .002) hypotension and more prolonged (16% vs 5%, P = .006) and late (26% vs 14%, P = .03) FHR decelerations. Increasing body mass index was associated with persistent systolic (odds ratio, 1.06; 95% confidence interval, 1.02-1.10) and diastolic (odds ratio, 1.04; 95% confidence interval, 1.01-1.06) hypotension after controlling for epidural bolus dose and hypertensive disorders.

CONCLUSION

Morbidly obese women have more hypotension and prolonged FHR decelerations following epidural anesthesia during labor at term.

Obese parturients have lower epidural local anaesthetic requirements for analgesia in labour †

BACKGROUND

There are no studies comparing local anaesthetic requirements for obese and normal parturients. Obesity has been associated with a higher incidence of Caesarean section and higher levels of epidural block have also been found in obese obstetric patients, suggesting they may require less local anaesthetic. The aim of our study was to estimate the minimum local analgesic concentration (MLAC) of bupivacaine for obese and non-obese parturients.

METHODS

Otherwise healthy parturients (n=32) requesting epidural analgesia were enrolled in this up-down sequential allocation study. Women were in active labour (3-6 cm cervical dilatation) with visual analogue pain scores (VAPS) >40/100 mm. Subjects with BMI >30 kg m(-2) were allocated to the obese group and BMI < or = 30 kg m(-2) were allocated to the normal group. The initial epidural dose for both groups was 20 ml 0.1% w/v bupivacaine (20 mg), with a dosing increment of 0.01% w/v VAPS < or = 10/100 mm defined effective analgesia. The MLAC was estimated using up-down reversals and probit regression with P<0.05 as significant.

RESULTS

Groups were similar except for BMI and weight (P<0.001). Local anaesthetic requirements were significantly (P<0.001) reduced by a factor of 1.68 (95% CI 1.32-2.29) in the obese group, with significantly higher initial level of block (P<0.001).

CONCLUSION

We found obese parturients to have significantly decreased epidural bupivacaine analgesic requirements. A contributing factor to obese patients having more difficult labours may be that relatively larger doses of local anaesthetic are administered than actually required. It may be worth considering lowering the concentrations and doses with which we initiate analgesia in obese parturients.

Epidural pressure and its relation to spread of epidural analgesia

The relationships between the epidural pressures following the injection of local anesthetic solution and the spread of epidural analgesia were investigated. In 46 patients, 15 ml of 2% mepivacaine was injected into the lumbar epidural space at a constant rate (1 ml/sec) using an electropowered syringe pump. Injection pressures and residual pressures were recorded and the spread of analgesia to pinprick was assessed. The changes of the epidural pressures during and following the injection of a volume of local anesthetic solution in old subjects were significantly smaller than those in young subjects (P < 0.05). The spread of analgesia closely correlated with the epidural pressures during and following the injection of local anesthetic solution. The most close correlation was found between the epidural pressure immediately after the completion of injection and the spread of analgesia (r = -0.5659, P < 0.001). In conclusion, the lower the terminal injection pressure and the residual pressures associated with higher age, the wider the spread of epidural analgesia.