Predictors of Breakthrough Pain During Labor Epidural Analgesia

Neuraxial initiation techniques for labor analgesia: Comparative insights on standard epidural, combined spinal-epidural and dural puncture epidural analgesia

PURPOSE OF REVIEW

In recent years, initiation techniques for neuraxial labor analgesia have focused on enhancing analgesic quality while minimizing complications. This review aims to summarize recent evidence on the standard epidural (EPL), combined spinal-epidural (CSE), and dural puncture epidural (DPE) techniques, emphasizing their benefits, risks, and relevance in contemporary obstetric anesthesia care.

RECENT FINDINGS

The DPE technique offers unique values, combining the advantages from CSE and EPL techniques. DPE and CSE, compared with EPL, techniques involve a dural puncture with a spinal needle, and the resulting epidural-intrathecal conduit enables translocation of analgesic agents, providing faster onset, earlier sacral coverage, better catheter function, and more rapid epidural extension to surgical anesthesia. Moreover, by limiting the intrathecal dose administered with the CSE technique, the DPE technique lowers the risks of fetal bradycardia and pruritus.

SUMMARY

EPL and CSE techniques are widely used for neuraxial labor analgesia. The DPE technique offers a novel alternative, delivering high-quality analgesia with minimal complications. While the benefits of the DPE technique are increasingly being recognized, additional comparative research will better support anesthesiologists in selecting the most appropriate technique across diverse clinical scenarios.

The 90% effective concentration of alfentanil combined with 0.075% ropivacaine for epidural labor analgesia: a single-center, prospective, double-blind sequential allocation biased-coin design

PURPOSE

More literature studies have reported that alfentanil is safe and effective for labor analgesia. However, there is no unified consensus on the optimal dosage of alfentanil used for epidural analgesia. This study explored the concentration at 90% of minimum effective concentration (EC90) of alfentanil combined with 0.075% ropivacaine in patients undergoing epidural labor analgesia to infer reasonable drug compatibility and provide guidance for clinical practice.

METHODS

In this prospective, single-center, double-blind study, a total of 45 singleton term primiparas with vaginal delivery who volunteered for epidural labor analgesia were recruited. The first maternal was administered with 3 μg/mL alfentanil combined with 0.075% ropivacaine with the infusion of 10 mL of the mixture every 50 min at a background dose of 3 mL/h. In the absence of PCEA, a total of 15 mL of the mixture is injected per hour. The subsequent alfentanil concentration was determined on the block efficacy of the previous case, using an up-down sequential allocation with a bias-coin design. 30 min after epidural labor analgesia, the block of patient failed with visual analog score (VAS) > 3, the alfentanil concentration was increased in a 0.5 μg/mL gradient for the next patient, while the block was successful with VAS ≤ 3, the alfentanil concentration was remained or decreased in a gradient according to a randomized response list for the next patient. EC90 and 95% confidence interval were calculated by linear interpolation and prediction model with R statistical software.

RESULTS

In this study, the estimated EC90 of alfentanil was 3.85 μg/mL (95% confidence interval, 3.64-4.28 μg/mL).

CONCLUSION

When combined with ropivacaine 0.075%, the EC90 of alfentanil for epidural labor analgesia is 3.85 μg/mL in patients undergoing 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.

Quality of Labor Analgesia with Dural Puncture Epidural versus Standard Epidural Technique in Obese Parturients: A Double-blind Randomized Controlled Study

BACKGROUND

The dural puncture epidural technique may improve analgesia quality by confirming midline placement and increasing intrathecal translocation of epidural medications. This would be advantageous in obese parturients with increased risk of block failure. This study hypothesizes that quality of labor analgesia will be improved with dural puncture epidural compared to standard epidural technique in obese parturients.

METHODS

Term parturients with body mass index greater than or equal to 35 kg · m-2, cervical dilation of 2 to 7 cm, and pain score of greater than 4 (where 0 indicates no pain and 10 indicates the worst pain imaginable) were randomized to dural puncture epidural (using 25-gauge Whitacre needle) or standard epidural techniques. Analgesia was initiated with 15 ml of 0.1% ropivacaine with 2 µg · ml-1 fentanyl, followed by programed intermittent boluses (6 ml every 45 min), with patient-controlled epidural analgesia. Parturients were blinded to group allocation. The data were collected by blinded investigators every 3 min for 30 min and then every 2 h until delivery. The primary outcome was a composite of (1) asymmetrical block, (2) epidural top-ups, (3) catheter adjustments, (4) catheter replacement, and (5) failed conversion to regional anesthesia for cesarean delivery. Secondary outcomes included time to a pain score of 1 or less, sensory levels at 30 min, motor block, maximum pain score, patient-controlled epidural analgesia use, epidural medication consumption, duration of second stage of labor, delivery mode, fetal heart tones changes, Apgar scores, maternal adverse events, and satisfaction with analgesia.

RESULTS

Of 141 parturients randomized, 66 per group were included in the analysis. There were no statistically or clinically significant differences between the dural puncture epidural and standard epidural groups in the primary composite outcome (34 of 66, 52% vs. 32 of 66, 49%; odds ratio, 1.1 [0.5 to 2.4]; P = 0.766), its individual components, or any of the secondary outcomes.

CONCLUSIONS

A lack of differences in quality of labor analgesia between the two techniques in this study does not support routine use of the dural puncture epidural technique in obese parturients.

EDITOR’S PERSPECTIVE

Analgesic considerations for induction of labor

Induction of labor may be indicated to minimize maternal and fetal risks. The rate of induction is likely to increase as recent evidence supports elective induction at 39 weeks gestation. We review methods of induction and then analgesic options as they relate to indications and methods to induce labor. We specifically focus on parturients at high risk for anesthetic complications including those requiring anticoagulation, and those with cardiac disease, obesity, chorioamnionitis, prior spinal instrumentation, elevated intracranial pressure, known or anticipated difficult airway, thrombocytopenia, and preeclampsia. Guidelines regarding timing of anticoagulation dosing with neuraxial anesthetic techniques have been defined through consensus statements. Early epidural placement may be beneficial in patients with cardiac disease, obesity, anticipated difficult airway, and HELLP syndrome. Questions remain regarding how early is too early for epidural placement, what options are safest for patients with bacteremia, and what pain relief should be offered to those unable to tolerate cervical exams in early labor.

Is breakthrough pain better managed by adding programmed intermittent epidural bolus to a background infusion during labor epidural analgesia? A randomized controlled trial

BACKGROUND

Breakthrough pain (BTP) is a common problem during labor analgesia. Programmed intermittent epidural bolus (PIEB) has demonstrated superior to background epidural infusion (BEI) concerning BTP, but the effect of combining both modes remains unknown. We hypothesized that this combination could reduce BTP incidence.

METHODS

Nulliparous parturients with early cervical dilation were randomized to receive 5 mL/h BEI of levobupivacaine 0.125% plus fentanyl 1.45 µg/mL (standard group) or 5 mL/h BEI + 10 mL/h PIEB (PIEB group). In case of BTP, patient-controlled epidural analgesia (PCEA) boluses of 10 mL (20-min lockout interval) were administered. If PCEA was insufficient, a 10-mL clinician bolus was delivered. The primary endpoint was the percentage of parturients who required supplementary epidural boluses.

RESULTS

One hundred and twenty women were recruited. Eighty-nine percent of parturients required supplementary boluses in standard group versus 30% in PIEB group (RR=3.07; 95% CI: 1.99-4.76; P<0.001). Adding PIEB prevented BTP in 70% of cases. Duration of effective analgesia was longer in PIEB than in standard group (P=0.003). Supplementary boluses were decreased (P<0.001), while local anesthetic consumption increased (P<0.001) by PIEB addition. Sensory-motor block, mode of delivery, maternal satisfaction and neonatal outcomes were equally distributed in both groups.

CONCLUSIONS

Adding PIEB to BEI+PCEA improved labor analgesia by significantly reducing the needs of rescue analgesia and prolonging the duration of effective analgesia. This combination provoked a higher consumption of local anesthetic with no detected clinical consequences.

Labor epidural analgesia onset time and subsequent analgesic requirements: a prospective observational single-center cohort study

BACKGROUND

We investigated the correlation between lumbar epidural analgesia onset time and pain intensity at 60 and 120 min after initiation.

METHODS

We conducted a prospective observational study of nulliparous women receiving lumbar epidural analgesia (initial bolus 15 mL bupivacaine 0.1% with fentanyl 3.33 μg/mL), followed by patient-controlled epidural analgesia (PCEA). The measured variable was lumbar epidural analgesia onset time (time to pain numerical rating score ≤3). Secondary outcomes were pain score at 60 and 120 min and at full dilatation; and analgesic requirements through the labor.

RESULTS

One-hundred-and-five women were eligible for analysis. There was a significant correlation between lumbar epidural analgesia onset time and pain intensity at 60 min (Spearman's R²=0.286, P=0.003), but not at 120 min (R²=0.030, P=0.76). Women who requested more PCEA boluses during the first 120 min had a longer lumbar epidural analgesia onset time (R²=0.321, P=0.001) and reported higher pain scores at 60 min (R²=0.588, P <0.001) and at 120 min (R²=0.539, P <0.001). Women who reported higher pain scores at 60 min had more pain at 120 min (R²=0.47, P <0.001) and higher analgesic consumption during labor (R²=0.403, P <0.001). Women who were at a greater cervical dilatation at 60 and 120 min had higher pain scores at the same time point (R²=0.259, P=0.008 and R²=0.243, P=0.013 respectively).

CONCLUSION

There was a correlation between the onset time of lumbar epidural analgesia during labor and the pain score 60 min later but this had disappeared by 120 min.

Development and validation of a predictive risk factor model for epidural re-siting in women undergoing labour epidural analgesia: a retrospective cohort study

Background

Epidural catheter re-siting in parturients receiving labour epidural analgesia is distressing to the parturient and places them at increased complications from a repeat procedure. The aim of this study was to develop and validate a clinical risk factor model to predict the incidence of epidural catheter re-siting in labour analgesia.

Methods

The data from parturients that received labour epidural analgesia in our centre during 2014–2015 was used to develop a predictive model for epidural catheter re-siting during labour analgesia. Multivariate logistic regression analysis was used to identify factors that were predictive of epidural catheter re-siting. The forward, backward and stepwise variable selection methods were applied to build a predictive model, which was internally validated. The final multivariate model was externally validated with the data collected from 10,170 parturients during 2012–2013 in our centre.

Results

Ninety-three (0.88%) parturients in 2014–2015 required re-siting of their epidural catheter. The training data set included 7439 paturients in 2014–2015. A higher incidence of breakthrough pain (OR = 4.42), increasing age (OR = 1.07), an increased pain score post-epidural catheter insertion (OR = 1.35) and problems such as inability to obtain cerebrospinal fluid in combined spinal epidural technique (OR = 2.06) and venous puncture (OR = 1.70) were found to be significantly predictive of epidural catheter re-siting, while spontaneous onset of labour (OR = 0.31) was found to be protective. The predictive model was validated internally on a further 3189 paturients from the data of 2014–2015 and externally on 10,170 paturients from the data of 2012–2013. Predictive accuracy of the model based on C-statistic were 0.89 (0.86, 0.93) and 0.92 (0.88, 0.97) for training and internal validation data respectively. Similarly, predictive accuracy in terms of C-statistic was 0.89 (0.86, 0.92) based on 2012–2013 data.

Conclusion

Our predictive model of epidural re-siting in parturients receiving labour epidural analgesia could provide timely identification of high-risk paturients required epidural re-siting.

Ultrasound guided L5-S1 placement of labor epidural does not improve dermatomal block in parturients

BACKGROUND

Based on their experience or training, anesthesiologists typically use the iliac crest as a landmark to choose the L3-4 or L2-3 interspace for labor epidural catheter placement. There is no evidence-based recommendation to guide the exact placement. We hypothesized that lower placement of the catheter would lead to a higher incidence of S2 dermatomal block and improved analgesia in late labor and at delivery.

METHODS

One-hundred parturients requesting epidural analgesia were randomly assigned to receive ultrasound-guided L5-S1 epidural catheter placement (experimental group) or non-ultrasound-guided higher lumbar interspace placement (control group). The primary outcome was the incidence of S2 block 30 minutes after administering 10 mL 0.125% bupivacaine. Secondary outcomes were average pain throughout labor and maximum pain during labor or during delivery.

RESULTS

Forty-nine subjects were enrolled in control group and 47 in the experimental group. The primary endpoint did not significantly differ between groups (control group 81% vs experimental group 91%, P=0.24). The secondary endpoints were not significantly different: pain relief after 30 minutes (mean pain score 1.4 in the control group vs 1.9 in the experimental group, P=0.2) and pain at delivery (mean score 4 in the control group vs 3.9 in the experimental group, P=0.6).

CONCLUSION

Placement of an epidural catheter at the L5-S1 interspace using ultrasound did not improve sacral sensory block coverage when compared with an epidural catheter placed at a higher lumbar interspace, without using ultrasound guidance.

The impact of analgesic intervention during the second stage of labour: a retrospective cohort study

PURPOSE

The incidence of epidural top-ups received in the second stage of labour in nulliparous women and the obstetrical and neonatal implications associated with these boluses are explored in this retrospective observational study. We hypothesized that an epidural top-up in the second stage of labour reduces operative deliveries by resolving inadequate analgesia.

METHODS

A population-based cohort analysis was performed using perinatal data from 1 January 2013 through 31 December 2014. An anesthesia database provided information to determine the top-up incidence. Women with or without a top-up for second-stage duration were compared for method of delivery and neonatal characteristics using descriptive statistics. Logistic regression identified predictive factors for method of delivery.

RESULTS

Of the 1,462 women with a second stage of labour > one hour who received epidural analgesia, 105 (7%) required a top-up during the second stage of labour. Women who received a top-up were more likely to have had induction of labour and/or augmentation (89% vs 76%; odds ratio [OR], 2.43; 95% confidence interval [CI], 1.32 to 4.49; P = 0.003), a longer second stage (303 min vs 171 min; mean difference, 132 min; 95% CI, 113 to 151; P < 0.001), and more assisted vaginal (41% vs 17%; OR, 3.35; 95% CI, 2.21 to 5.1; P < 0.001) or Cesarean deliveries (26% vs 11%; OR, 3.04; 95% CI, 1.91 to 4.8; P < 0.001) than women without a top-up.

CONCLUSION

Most women who received a top-up had a vaginal (spontaneous or assisted) delivery. Compared with women without a top-up, women requiring a top-up had more predictors of difficult labour and higher rates of assisted vaginal delivery and Cesarean delivery.

The influence of women's attachment style on the chronobiology of labour pain, analgesic consumption and pharmacological effect

Circadian variation in biological rhythms has been identified as affecting both labour pain and the pharmacological properties of analgesics. In the context of pain, there is also a growing body of evidence suggesting the importance of adult attachment. The purpose of this study was to examine whether labour pain, analgesic consumption and pharmacological effect are significantly affected by the time of day and to analyse whether this circadian variation is influenced by women's attachment style. This prospective observational study included a sample of 81 pregnant women receiving patient-controlled epidural analgesia (PCEA). Attachment was assessed with the Adult Attachment Scale - Revised. The perceived intensity of labour pain in the early stage of labour (3 cm of cervical dilatation and before the administration of PCEA) was measured using a visual analogue scale (VAS). Pain was also indirectly assessed by measuring the consumption of anaesthetics. The latency period and the duration of effect were recorded for a chronopharmacology characterisation. Pain, as assessed with the VAS, was significantly higher in the night-time group than in the daytime group. An insecure attachment style was significantly associated with greater labour pain at 3 cm of cervical dilatation (p < 0.001) and before the beginning of analgesia (p < 0.001) as well as with higher analgesic consumption and lower pharmacological efficacy (p < 0.05). The time of day was significantly associated with the pharmacological effect: the latency period was longer at night, and the duration of the pharmacological effect was longer during the daytime. The interaction between time of day and attachment style was not significant for any of the study variables. Our results provide evidence of the importance of circadian variation in studying labour pain and the pharmacological effect of labour analgesia involving epidural blockage with a PCEA regimen. Moreover, although there was no evidence that attachment style influenced the circadian variation, these data emphasise that insecure attachment patterns are a risk factor for greater labour pain and analgesic consumption, which should be considered in pain management approaches.

Attachment styles, pain, and the consumption of analgesics during labor: a prospective observational study

Individuals with less secure attachment styles have been shown to experience more pain than people with more secure attachment styles; however, attachment styles have not yet been examined in the context of labor pain and analgesic consumption. The purpose of this prospective observational study was to assess the influence of the mother's attachment style on the perception of labor pain, as assessed by a visual analog scale and analgesic consumption. Eighty-one pregnant women with a mean age of 32 years (standard deviation = 5.1) were assessed during the third trimester of pregnancy and during labor. The physical predictors of labor pain were recorded, and the adult attachment style was assessed with the Adult Attachment Scale-Revised. For labor analgesia, a low dose of patient-controlled epidural analgesia protocol (ropivacaine .6 mg/mL plus sufentanil .5 μg/mL) was used. Women with a secure attachment style reported significantly less labor pain (P < .001) and a significantly lower analgesic consumption during labor (P < .001) than insecurely attached women. These findings suggest that women's attachment style was associated with labor pain and analgesic consumption and support the relevance of the attachment theory as a promising conceptual framework for understanding labor pain.

PERSPECTIVE

This study showed that women with an insecure attachment style were more likely to report higher pain before patient-controlled epidural analgesia and higher analgesic consumption and to request supplemental analgesia during labor. The assessment of adult attachment has the potential to identify women at high risk of poorly coping with pain during childbirth.

Duration of analgesia and pruritus following intrathecal fentanyl for labour analgesia: no significant effect of A118G μ-opioid receptor polymorphism, but a marked effect of ethnically distinct hospital populations

BACKGROUND

Genetic polymorphism (A118G) in the μ-opioid receptor has been reported to affect systemic opioid analgesia. However, reported pharmacogenetic effects on spinal opioid analgesia, particularly in labour, have been equivocal.

METHODS

We prospectively assessed effects of the μ-opioid receptor A118G single nucleotide polymorphism (SNP) on analgesia after 20 μg of spinal fentanyl. We studied two ethnically distinct hospital populations (Miami and Jerusalem). Independent variables were A118G, ethnicity, and hospital. Primary outcome was time from spinal analgesia until analgesic request. Secondary outcomes were pain and pruritus, assessed at repeated intervals until analgesia request.

RESULTS

One hundred and twenty-five nulliparous parturients in early labour were analysed. The allelic frequency of A118G was 14.8% (14.4% in Miami; 15.5% in Jerusalem). Time to analgesia request (sd) in Miami was 122 (44) min and in Jerusalem was 87 (32) min, P<0.001; Hispanic 123 (46) min vs Jew/Arab 87 (32) min, P<0.001; Black 121 (41) min vs Jew/Arab 87 (32) min, P=0.015. There was no significant effect of A118G. Survival analysis showed Miami > Jerusalem, P<0.001; Hispanics and Black > Jew/Arab, P<0.001; no effect of A118G. Within hospital groups, A118G had no effect on time to analgesic request; within genomic groups there was a significant difference between hospitals. The time-course for pruritus exactly paralleled the time-course for analgesia and was affected by hospital (P=0.006) and by ethnic group (P=0.03), but not by A118G.

CONCLUSIONS

We found no significant effect for the A118G single nucleotide polymorphism (SNP) on analgesic duration after spinal fentanyl for labour. In contrast, ethnically distinct hospital population groups exerted a marked effect on the time-course of both analgesia and pruritus.

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.

Episodic (breakthrough) pain prevalence in a population of cancer pain patients. Comparison of clinical diagnoses with the QUDEI--Italian questionnaire for intense episodic pain

CONTEXT

Breakthrough/episodic pain (BP-EP) diagnosis is often based on clinical experience, and different opinions exist, even among palliative care clinicians, about its definition and application to clinical practice.

OBJECTIVES

The primary aim of this study was to assess the prevalence and clinical characteristics of BP-EP in an unselected Italian population of patients with cancer-related chronic pain, based on clinical diagnosis and on the use of an assessment tool, the Questionnaire for Intense Episodic Pain (QUDEI).

METHODS

A cross-sectional multicenter prevalence study of 240 consecutive cancer pain patients was carried out. The physicians participating in the study attended a training session aimed at defining and recognizing BP-EP. The QUDEI, a screening and assessment tool based on patient interview, diagnosed the presence of BP-EP in patients regularly taking analgesics for the previous three days and who had at least one pain flare in the previous 24 hours. Clinical evaluation and questionnaire application were carried out by different health care providers.

RESULTS

The estimated prevalence of BP-EP was 73% (95% confidence interval [CI] = 67%, 79%) when the diagnosis was made by physicians and 66% (95% CI = 60%, 72%) when the QUDEI was applied (86% agreement). When only patients with baseline pain less than or equal to six were included in the analysis, the above prevalences decreased to 67% and 60%, respectively.

CONCLUSION

Because BP-EP is a significant phenomenon in cancer pain management, its appropriate recognition requires a more widely, internationally accepted general definition and specific validated tools for its screening and evaluation.

Modern neuraxial labor analgesia: options for initiation, maintenance and drug selection

In the present review we outline the state-of-the-art of neuraxial analgesia. As neuraxial analgesia remains the gold standar of analgesia during labor, we review the most recent literature on this topic. The neuraxial analgesia techniques, types of administration, drugs, adjuvants, and adverse effects are investigated from the references. Most authors would agree that central neuraxial analgesia is the best form to manage labor pain. When neuraxial analgesia is administered to the parturient in labor, different management choices must be made by the anesthetist: how will we initiate analgesia, how will analgesia be maintained, which local anesthetic will we use for neuraxial analgesia and which adjuvant drugs will we combine? The present manuscript tries to review the literature to answer these questions.

Anesthesia for the morbidly obese parturient

PURPOSE OF REVIEW

Obesity is a growing healthcare problem worldwide, which also affects the pregnant population. Obesity occurs with increasing frequency during pregnancy. Obesity increases the maternal, fetal and neonatal risks. Also, the anesthesiologist is confronted with significantly more problems when the parturient is overweight or obese. The present review focuses on the anesthetic implications of obesity in pregnancy.

RECENT FINDINGS

In recent years, many authors have stressed the consequences of obesity in pregnancy. More pregnancy-associated complications such as preeclampsia occur, and more medical interventions are also required such as operative delivery, when patients are obese compared with the nonobese population. Recent anesthetic evidence also shows that obese parturients are at increased risk of anesthesia-related complications such as failed intubation and aspiration.

SUMMARY

Anesthesia-related complications are more frequent in obese parturients. Most authors and opinion leaders agree that regional anesthesia is the preferred technique for Cesarean section in obese patients, and that efforts to place early labor epidural analgesia should be optimized in order to be able to avoid general anesthesia when unplanned Cesarean section is required.

A randomized trial of breakthrough pain during combined spinal-epidural versus epidural labor analgesia in parous women

BACKGROUND

There is controversy regarding the benefits and risks of combined spinal-epidural compared with epidural analgesia (CSE, EPID) for labor analgesia. We hypothesized that CSE would result in fewer patient requests for top-up doses compared to EPID.

METHODS

One-hundred ASA physical status I or II parous women at term in early labor (<5 cm cervical dilation) requesting analgesia were randomized in double-blind fashion to the EPID group (epidural bupivacaine 2.5 mg/mL, 3 mL, followed by bupivacaine 1.25 mg/mL, 10 mL with fentanyl 50 microg) or the CSE group (intrathecal bupivacaine 2.5 mg with fentanyl 25 microg). Both groups received identical infusions of bupivacaine 0.625 mg/mL with fentanyl 2 microg/mL at 12 mL/h. The primary outcome variable was the number of top-up doses requested to treat breakthrough pain.

RESULTS

There was no significant difference between the two groups in the percentage of patients requesting top-up doses (44% CSE vs 51% EPID; 95% confidence interval of the difference -28% to +14%) nor in the need for multiple top-up doses (14% CSE vs 15% EPID). Visual analog scale scores were lower in the CSE group compared to the EPID group at 10 min after initiation of analgesia [median 0 cm (0, 0) vs 4 cm (1, 6) respectively, P < 0.001] and at 30 min [0 cm (0, 0) vs 0 cm (0, 1), respectively, P = 0.03].

CONCLUSIONS

We did not find a difference in the need for top-up doses in parous patients; however, CSE provided better analgesia in the first 30 min compared to EPID.

Analgesic efficacy using loss of resistance to air vs. saline in combined spinal epidural technique for labour analgesia

Identification of the epidural space is often performed using the loss of resistance technique to either air or saline. We sought to investigate if the medium used affected the quality of analgesia obtained by parturients who received labour epidurals. We conducted a retrospective audit of labour epidurals performed on nulliparous parturients in our institution from May 2003 to March 2005. All epidural catheters were inserted by senior obstetric anaesthetists using a combined spinal epidural technique. The following information was recorded: parturients' demographic data, loss of resistance technique used, type and amount of local anaesthetic solution administered, complications encountered during procedure, pre-block and post-block pain scores, incidence of breakthrough pain requiring supplemental medication and post-block side-effects. Data from 2848 patients were collected and analysed; 56% of patients made up the saline group and 44% the air group. Patients in both groups had similar demographic profiles and similar incidences of complications and post-block side-effects. However patients in the air group had a higher incidence of recurrent breakthrough pain P = 0.023). We also identified three other factors that were associated with an increased incidence of recurrent breakthrough pain; administration of pre-block oxytocin, sitting position of the parturient during the procedure and the use of intrathecal bupivacaine for induction of analgesia. Our findings suggest that a loss of resistance to air is associated with a higher incidence of recurrent breakthrough pain among parturients who received combined spinal epidural analgesia for labour than a loss of resistance to saline.

Obstetric anesthesia for the obese and morbidly obese patient: an ounce of prevention is worth more than a pound of treatment

BACKGROUND

The incidence of obesity has been dramatically increasing across the globe. Anesthesiologists, are increasingly faced with the care for these patients. Obesity in the pregnant woman is associated with a broad spectrum of problems, including dramatically increased risk for cesarean delivery, diabetes, hypertension and pre-eclampsia. A thorough understanding of the physiology, associated conditions and morbidity, available options for anesthesia and possible complications is therefore important for today's anesthesiologist.

METHODS

This is a personal review in which different aspects of obesity in the pregnant woman, that are relevant to the anesthesiologist, are discussed. An overview of maternal and fetal morbidity and physiologic changes associated with pregnancy and obesity is provided and different options for labor analgesia, the anesthetic management for cesarean delivery and potential post-partum complications are discussed in detail.

RESULTS AND CONCLUSION

The anesthetic management of the morbidly obese parturient is associated with special hazards. The risk for difficult or failed intubation is exceedingly high. The early placement of an epidural or intrathecal catheter may overcome the need for general anesthesia, however, the high initial failure rate necessitates critical block assessment and catheter replacement when indicated.

Breakthrough pain characteristics and syndromes in patients with cancer pain. An international survey

Breakthrough pain (BKP) is a transitory flare of pain that occurs on a background of relatively well controlled baseline pain. Previous surveys have found that BKP is highly prevalent among patients with cancer pain and predicts more severe pain, pain-related distress and functional impairment, and relatively poor quality of life. An international group of investigators assembled by a task force of the International Association for the Study of Pain (IASP) evaluated the prevalence and characteristics of BKP as part of a prospective, cross-sectional survey of cancer pain. Fifty-eight clinicians in 24 countries evaluated a total of 1095 patients with cancer pain using patient-rated items from the Brief Pain Inventory (BPI) and observer-rated measures. The observer-rated information included demographic and tumor-related data, the occurrence of BKP, and responses on checklists of pain syndromes and pathophysiologies. The clinicians reported BKP in 64.8% of patients. Physicians from English-speaking countries were significantly more likely to report BKP than other physicians. BKP was associated with higher pain scores and functional interference on the BPI. Multivariate analysis showed an independent association of BKP with the presence of more than one pain, a vertebral pain syndrome, pain due to plexopathy, and English-speaking country. These data confirm the high prevalence of BKP, its association with more severe pain and functional impairment, and its relationship to specific cancer pain syndromes. Further studies are needed to characterize subtypes of BKP. The uneven distribution of BKP reporting across pain specialists from different countries suggests that more standardized methods for diagnosing BKP are needed.