The effect of epidural test dose on motor function after a combined spinal-epidural technique for labor analgesia

A Prospective Randomized Trial of Ropivacaine 5 mg with Sufentanil 2.5 μg as a Test Dose for Detecting Epidural and Intrathecal Injection in Obstetric Patients

Objectives: Traditional epidural test dose is somewhat unsuited in obstetrics because of potential risk of severe adverse effects when it is accidentally injected into the subarachnoid space. Some hospitals use a proportion of the total dose of epidural labor analgesia as a test dose. The aim of our study was to assess the effectiveness and safety of ropivacaine 5 mg with sufentanil 2.5 μg to detect intrathecal injection. Methods: This prospective randomized study enrolled parturients who had the demand for epidural labor analgesia and randomly divided them into two groups. Then, 5 mL of 0.1% ropivacaine with sufentanil 2.5 μg was injected into the epidural space or the subarachnoid space in the epidural (EP) group and the intrathecal (IT) group, respectively. The ability to detect intrathecal injection and side effects were assessed to work out the effectiveness and safety. Results: For spinal injection, the sensitivity and the specificity of the symptoms of either warmth or numbness or both assessed at 3 min were both 100%, and the observed negative predictive value (NPV) and positive predictive value (PPV) were 100%. All parturients in the IT group and 2.33% of parturients in the EP group had sensory blockade to cold or pinprick (p < 0.0001). A total of 77.55% (38 of 49) of parturients in the IT group were found to have a motor block. A 10 min assessment showed the median cephalad cold and pin levels were T8 and T10, respectively, and the median Bromage score was 4 in the IT group. Incidences of adverse effects in both groups were low. Conclusions: Ropivacaine 5 mg with sufentanil 2.5 μg is effective and safe to detect intrathecal injection as an epidural test dose in obstetric patients.

Epidural test dose in obstetric patients: should we still use it?

PURPOSE OF REVIEW

As the application of a test dose after epidural catheter insertion in obstetrics has recurrently been associated with serious adverse events affecting both maternal and foetal outcomes, the question whether to test or not remains a controversial issue.

RECENT FINDINGS

Present guidelines do not provide clear recommendations in this regard and several recent surveys indicate a heterogeneity in clinical routine.

SUMMARY

Physiological alterations during pregnancy and labour restrict the use and also the validity of traditional test agents. Epinephrine is not appropriate to detect a vascular insertion in labour and the application of a local anaesthetic test dose may lead to dose-dependent fatal consequences should the catheter be intrathecal, due to an increased sensitivity in parturients. Given the current practice of opioid-amended-low-concentration epidurals, the waiving of a test dose results at worst in a failed epidural, a stark contrast to the potentially severe to fatal complications of a 'traditional' test dose. Hence, an originally preventive measure providing potentially more harm than the consequences of the situation aimed to prevent, should not be recommended. A simple fractionated administration of the initial analgesic dose seems reasonable though.

Isometric force dynamometer is superior to bromage score in prediction of patients' ambulation after spinal anesthesia in ambulatory surgeries

BACKGROUND

The aim of our study was to use a quantitative measure of muscle strength to identify the muscle power at which the patient can safely ambulate unassisted after spinal anesthesia.

METHODS

Twenty ASA physical status I and II patients undergoing elective perineal or lower abdominal surgery under spinal anesthesia were enrolled in the study. Spinal anesthesia was conducted using 10 mg heavy bupivacaine. The regression of motor block was assessed both qualitatively using the Bromage score and quantitatively by measuring the isometric contraction of the knee, hip, and ankle flexors every 15 minutes until the patient was able to ambulate unassisted.

RESULTS

The rate of regression of the Bromage score was faster than regression of the isometric forces at all tested joints. As the median Bromage score reached 0 (no motor blockade), the mean±SD motor power recoveries at the knee, hip, and ankle were 28.2%±16%, 45.5%±24%, and 56.3%±28 %, respectively, and only 6 of 20 patients (30%, 95% confidence interval 10%-53%) were able to walk unassisted. After 75 minutes passed, 90% of the patients (95% confidence interval 56%-99%) were able to walk unassisted with mean motor power recovery of 63.6%±20%, 82.1%±27%, and 90.2%±24% at the knee, hip, and ankle, respectively. The area under the receiver operating characteristic curves was significantly higher with isometric contraction at different joints than the Bromage score (P<0.001). In addition, isometric contraction at different joints was effective in predicting the patients' ability to walk unassisted after subarachnoid block with prediction probabilities of 0.901, 0.948, and 0.958 for the knee, hip, and ankle, respectively, as compared with 0.752 for the Bromage score (P<0.001).

CONCLUSION

Quantitative measurement of the degree of recovery of the motor power of the knee, hip, or ankle flexors is more accurate and superior to the qualitative Bromage score, as a predictor of the patient's ability to safely ambulate after spinal anesthesia. This may be recommended when assessing motor block when small-dose anesthetic solutions are used.

A prospective randomized trial of lidocaine 30 mg versus 45 mg for epidural test dose for intrathecal injection in the obstetric population

BACKGROUND

The epidural test dose, used to identify unintended intrathecal placement, should reliably produce a spinal block without posing a threat to the patient. Most anesthesiologists administer a dose of local anesthetic, commonly lidocaine 45 mg. Pregnant patients are more sensitive to local anesthetics; high and total spinal anesthesia have been reported in the pregnant population with this dose. We hypothesized that lidocaine 30 mg was as effective as lidocaine 45 mg in creating rapid objective evidence of a sensory or motor block.

METHODS

In this prospective, randomized, double-blind trial, patients scheduled for cesarean delivery were assigned to 1 of 4 groups: lidocaine 30 mg in the spinal or epidural space, or lidocaine 45 mg by the same routes. A blinded observer assessed the degree of sensory and motor block. The ability to identify intrathecal injection of each dose was compared. Sensory block above T6 dermatome and hypotension were recorded as side effects.

RESULTS

Intrathecal administration of lidocaine 30 mg produced rapid subjective and objective signs of neuroblockade within 3 minutes (100%, 95% confidence interval CI, 85%-100% for each). Lidocaine 45 mg produced similar results. All patients in both groups described their legs as warm or heavy after 3 minutes and had a motor block by 5 minutes. On the basis of an intrathecal catheter rate of 1:380, the observed negative predictive value for intrathecal placement if the patient described no sensory changes at 3 minutes was 100% (95% CI, 99.95%-100%) for 30 mg and 100% (95% CI, 99.93%-100%) for 45 mg. We did not identify a decrease in the rate of side effects with the lower dose.

CONCLUSIONS

Our results suggest that there is unlikely to be a large difference in the ability of these doses to detect unintentional intrathecal catheter placement. While the negative predictive value for intrathecal injection is very high for both doses, the 95% CI for the sensitivity of either dose is too wide to demonstrate clinical safety to identify all intrathecal catheters. A much larger study is warranted to assess whether there is a lower sensitivity with the 30-mg dose, or a propensity toward high cephalad motor block levels with the 45-mg dose.

Maternal ambulation during labor

PURPOSE OF REVIEW

To describe the recent advances in labor epidural analgesia, which may have an impact on maternal ambulation during labor.

RECENT FINDINGS

With the advent of new epidural adjuvant drugs and new epidural delivery systems, we are now able to use very low concentration local anesthetic solutions with a reduction in the total doses of local anesthetic administered. This allows a much greater preservation of lower limb motor function in the parturient, with a subsequent positive effect on maternal ambulation. Although it is well documented that maternal satisfaction scores are higher with ambulatory epidurals than with other more conventional epidural techniques, the other positive effects, such as shorter labor times, and a reduction in instrumental and cesarean delivery rates, thought to have been associated with ambulatory epidurals, have however been more difficult to prove.

SUMMARY

Since the earliest 'walking epidural' was described in the early 1990s, there has been much research into finding the ideal regional technique for labor analgesia that provides excellent analgesia with high maternal satisfaction scores while having little adverse effect on obstetric outcome. This review attempts to map the journey of the 'walking epidural' from its earliest form to its more recognizable modern day appearance.

Progress in analgesia for labor: focus on neuraxial blocks

Neuraxial analgesia is widely accepted as the most effective and the least depressant method of providing pain relief in labor. Over the last several decades neuraxial labor analgesia techniques and medications have progressed to the point now where they provide high quality pain relief with minimal side effects to both the mother and the fetus while maximizing the maternal autonomy possible for the parturient receiving neuraxial analgesia. The introduction of the combined spinal epidural technique for labor has allowed for the rapid onset of analgesia with minimal motor blockade, therefore allowing the comfortable parturient to ambulate. Patient-controlled epidural analgesia techniques have evolved to allow for more flexible analgesia that is tailored to the individual needs of the parturient and effective throughout the different phases of labor. Computer integrated systems have been studied to provide seamless analgesia from induction of neuraxial block to delivery. New adjuvant drugs that improve the effectiveness of neuraxial labor analgesia while decreasing the side effects that may occur due to high dose of a single drug are likely to be added to future labor analgesia practice. Bupivacaine still remains a popular choice of local anesthetic for labor analgesia. New local anesthetics with less cardiotoxicity have been introduced, but their cost effectiveness in the current labor analgesia practice has been questioned.

Obstetric spinal analgesia and anesthesia

PURPOSE OF REVIEW

The present overview will try to summarize the most important recent studies performed on spinal analgesia for labor pain treatment and spinal anesthesia for Cesarean section.

RECENT FINDINGS

Attention is focused on pharmacological and technical topics. The interest in demonstrating the benefits of the new local anesthetics over bupivacaine seems to have faded. The search for other adjuvant drugs continues, but it is not clear whether opioids need to be replaced or combined with other adjuvants. A large number of studies are still dealing with vasopressor treatment of hypotension during Cesarean section. There is growing evidence that ephedrine is no longer the vasopressor drug of choice and that phenylephrine should take its place. In technical studies, discussion on combined spinal-epidural versus epidural continues, but it remains difficult to provide definitive evidence that combined spinal-epidural is more advantageous. Also the increased possibility of ambulation has not resulted in benefits other than enhanced maternal satisfaction. Finally, spinal techniques seem to have lost their reputation as being a dangerous choice in patients with severe preeclampsia or cardiac disease.

SUMMARY

The new local anesthetics have established their position in obstetric regional anesthesia, but it remains difficult to demonstrate a superior outcome as compared with bupivacaine. The same is true for combined spinal-epidural and ambulation. Phenylephrine seems to have become the vasopressor of choice in the treatment of hypotension following spinal anesthesia. A more appropriate treatment of hypotension combined with a low-dose technique may enhance the safety of spinal anesthesia in preeclamptic patients or cases of severe cardiac disease.

Epidural clonidine added to a bupivacaine infusion increases analgesic duration in labor without adverse maternal or fetal effects

PURPOSE

Many obstetric patients receiving epidural analgesia are encouraged to ambulate. This current study was designed to determine the potential for maximizing the time to first epidural supplement when adding clonidine to a 0.625 mg.ml(-1) bupivacaine continuous epidural infusion following epidural fentanyl bolus in early labor for patients allowed to ambulate. Maternal and fetal effects secondary to clonidine were also evaluated.

METHODS

Sixty-eight laboring primigravid women received a 3-ml epidural test dose of lidocaine with epinephrine, followed by a fentanyl 100-microg bolus (in a 10 ml-volume). The patients then received a 0.625 mg.ml(-1) bupivacaine continuous epidural infusion, either with or without clonidine (5 microg.ml(-1)), at a rate of 10 ml.h(-1). Pain scores and side effects were recorded for each patient.

RESULTS

The overall quality of analgesia was similar in both groups. The mean duration prior to request for additional analgesia was significantly longer in the clonidine group (269 +/- 160 min), compared to the control group (164 +/- 64 min). No patient in either group experienced any detectable motor block; one patient (clonidine group) complained of mild thigh numbness and was not allowed to ambulate. While mean blood pressure was approximately 6 mmHg lower in the clonidine group at 1, 1.5, and 3.5 h, this was not clinically significant. No adverse effects on maternal heart rate or fetal heart rate were noted.

CONCLUSION

In early laboring patients, addition of clonidine prolongs the analgesia duration of a 0.625 mg.ml(-1) bupivacaine continuous epidural infusion following 100 microg epidural fentanyl (after a lidocaine-epinephrine test dose) without a clinically significant increase in side effects.

The Effect of a Lidocaine Test Dose on Analgesia and Mobility After an Epidural Combination of Neostigmine and Sufentanil in Early Labor

We previously demonstrated the effectiveness of epidural sufentanil and the cholinesterase inhibitor, neostigmine, to initiate selective labor analgesia. Because the traditional lidocaine plus epinephrine test dose (TD) may alter the effect of subsequent epidural drugs, we undertook this investigation to evaluate the impact of a lidocaine TD on analgesia from a combination of epidural neostigmine plus sufentanil administered in early labor. Eighty healthy parturients were randomly allocated to two groups to receive a 3 mL-TD, either lidocaine 2%-epinephrine (1:200,000) or saline-epinephrine (1:200,000), followed 3 min later by epidural neostigmine 500 microg plus sufentanil 10 microg. Pain scores were recorded for 30 min after injection, as was the time elapsed from initial bolus until request for supplemental analgesia. Thirty minutes after injection, adequacy of motor function was evaluated by the parturient's ability to sit, stand up, bend her knees, and walk. Lidocaine TD hastened the onset (5 min vs 15 min) and increased duration (122 +/- 53 min vs 98 +/- 54 min; P = 0.02) of analgesia from epidural neostigmine plus sufentanil bolus. In contrast, the TD did not significantly impair the ability to sit, stand up, or bend the knees. The ability to ambulate, however, was reduced (57% vs 82%; P = 0.04). In conclusion, a traditional lidocaine TD significantly enhances the analgesic effect from the epidural neostigmine plus sufentanil combination, but affects ambulation in early labor.

Obstetric epidural test doses: a survey of UK practice

BACKGROUND

With the advent of low-dose epidural analgesia in labour, the content of the test dose has once again become the subject of debate.

METHOD

A postal survey of 500 members of the Obstetric Anaesthetists' Association was conducted in 1999-2000, assessing the use of test doses during epidurals in labour and for caesarean section.

RESULTS

There was a 67% response rate. Test doses are used in labour, at elective caesarean section and before epidural top-up for emergency caesarean section, by 90%, 93% and 37%, respectively. There was large variation in both drugs and doses. During labour, doses of bupivacaine range from 3 to 20 mg and of lidocaine 15 to 90 mg. There has been a three-fold increase in the use of low-dose local anaesthetic test doses since a previous national survey in 1997. The size of local anaesthetic test doses used at caesarean section is also variable. Epinephrine is used in 5% of labour, 14% of elective and 34% of emergency caesarean sections. Signs and symptoms that are commonly sought after test doses include somatic motor block, blood pressure change, sensory effect and symptoms from systemic local anaesthetic. The effect of the test dose is usually assessed after 5 min.

CONCLUSION

There is no consensus about the nature of the ideal test dose in obstetric anaesthesia. There is a trend to use less concentrated test doses during labour. Doses that risk a high block if given spinally are still used. Epinephrine, aspiration testing and cardiovascular monitoring are uncommon.

What’s new and novel in obstetric anesthesia? Contributions from the 2003 scientific literature

THE PREGNANT PATIENT: Age; maternal disease; prophylactic antibiotics; gastroesophageal reflux; obesity; starvation; genotyping; coagulopathy; infection; substance abuse; altered drug responses in pregnancy; physiological changes of pregnancy. THE FETUS: Fetal monitoring; intrauterine surgery. THE NEWBORN: Breastfeeding; maternal infection, fever, and neonatal sepsis evaluation. OBSTETRIC COMPLICATIONS: Embolic phenomena; hemorrhage; preeclampsia; preterm delivery. OBSTETRIC MANAGEMENT: External cephalic version and cervical cerclage; elective cesarean delivery; fetal malpresentation; vaginal birth after cesarean delivery; termination of pregnancy. OBSTETRIC ANESTHESIA: Analgesia for labor and delivery; anesthesia for cesarean delivery; anesthesia for short obstetric operations; complications of anesthesia. MISCELLANEOUS: Consent; ethics; history; labor support; websites/books/leaflets/journal announcements.

Early rehabilitation after anterior cruciate ligament reconstruction under regional analgesia: a case report

Patients undergoing major knee surgery may experience postoperative pain, which could be exacerbated by early postoperative continuous passive motion or active mobilization. This pain may result in poor functional recovery. Use of regional analgesia techniques to achieve more consistent pain relief and to facilitate rapid rehabilitation can play an important role in optimizing postoperative outcome after anterior cruciate ligament repair (ACLR). This case study concerns a 20-year-old male soldier, otherwise healthy, who underwent ACLR. We inserted a catheter in the fascia iliaca compartment and performed postoperative analgesia with low-concentration ropivacaine by using an elastomeric pump. The patient started early rehabilitation under fascia iliaca compartment analgesia. We discuss the case and the influence of regional analgesia techniques on postoperative and clinical outcomes.