Kenneth E. Nelson

A comparison of epidural analgesia with 0.125% ropivacaine with fentanyl versus 0.125% bupivacaine with fentanyl during labor

We previously found that the extent of an epidural motor block produced by 0.125% ropivacaine was clinically indistinguishable from 0.125% bupivacaine in laboring patients. By adding fentanyl to the 0.125% ropivacaine and bupivacaine solutions in an attempt to reduce hourly local anesthetic requirements, we hypothesized that differences in motor block produced by the two drugs may become apparent. Fifty laboring women were randomized to receive either 0.125% ropivacaine with fentanyl 2 &mgr;g/mL or an equivalent concentration of bupivacaine/fentanyl using patient-controlled epidural analgesia (PCEA) with settings of: 6-mL/hr basal rate, 5-mL bolus, 10-min lockout, 30-mL/h dose limit. Analgesia, local anesthetic use, motor block, patient satisfaction, and side effects were assessed until the time of delivery. No differences in verbal pain scores, local anesthetic use, patient satisfaction, or side effects between groups were observed; however, patients administered ropivacaine/fentanyl developed significantly less motor block than patients administered bupivacaine/fentanyl. Ropivacaine 0.125% with fentanyl 2 &mgr;g/mL produces similar labor analgesia with significantly less motor block than an equivalent concentration of bupivacaine/fentanyl. Whether this statistical reduction in motor block improves clinical outcome or is applicable to anesthesia practices which do not use the PCEA technique remains to be determined. Implications: By using a patient-controlled epidural analgesia technique, ropivacaine 0.125% with fentanyl 2 &mgr;g/mL produces similar analgesia with significantly less motor block than a similar concentration of bupivacaine with fentanyl during labor. Whether this statistical reduction in motor block improves clinical outcome or is applicable to anesthesia practices which do not use the patient-controlled epidural analgesia technique remains to be determined.

A Comparison of Intrathecal Fentanyl and Sufentanil for Labor Analgesia

Background The use of intrathecal opioids for labor analgesia continues to gain popularity, but there are limited data to guide this use. Previously, the authors established the ED50 for 60 min of labor analgesia from intrathecal sufentanil using an up–down sequential allocation study design. The current study first establishes an ED50 for intrathecal fentanyl using this same study design to establish an intrathecal potency ratio for fentanyl and sufentanil and then uses this ratio to compare the efficacy, duration of analgesia, and side effects from comparable doses of intrathecal fentanyl and sufentanil. Methods Seventy-five healthy nulliparous women requesting labor analgesia were enrolled in this two-part study. In phase I, 20 women received varying doses of fentanyl to establish an ED50 for 60 min of labor analgesia. In phase II, 55 women were randomized to receive either 36 &mgr;g intrathecal fentanyl or 8 &mgr;g sufentanil (2 times the ED50s) via a combined spinal–epidural technique and by double-blinded design. Pain relief, side effects, block height, maternal hemodynamics, and fetal heart rate were assessed throughout the study. The duration of spinal analgesia was considered to be the time from injection of study drug to the time of the patients first request for additional analgesia. Results The ED50 of intrathecal fentanyl for 60 min of labor analgesia was found to be 18.2 &mgr;g, and therefore, the potency ratio of intrathecal sufentanil to intrathecal fentanyl at the ED50 level is 4.4:1. The duration of spinal analgesia was significantly longer from 8 &mgr;g intrathecal sufentanil than from 36 &mgr;g intrathecal fentanyl (104 ± 34 vs. 79 ± 34 min, P = 0.009). Otherwise, patient demographics, maternal hemodynamics, duration of labor, mode of delivery, motor block, subjective leg weakness, pruritus, nausea, pinprick sensory levels, visual analog scale pain scores, fetal bradycardia, and Apgar scores were similar between groups. Conclusion The relative potency of intrathecal sufentanil to fentanyl for labor analgesia is 4.4:1. When using intrathecal opioids alone for early labor analgesia, 8 &mgr;g sufentanil produces labor analgesia lasting approximately 25 min longer than from 36 &mgr;g fentanyl, without a statistically significant increase in side effects. However, when making a choice between fentanyl and sufentanil, one must consider other important factors, such as the higher cost of sufentanil and the greater risk of dosing error due to the higher potency of sufentanil compared with fentanyl.

Intrathecal Neostigmine and sufentanil for early labor analgesia

BACKGROUND Recent efforts to improve the combined spinal epidural (CSE) technique have focused on adding opioids to other classes of analgesics. In this study, the authors used intrathecal neostigmine in combination with intrathecal sufentanil to investigate the usefulness of neostigmine for reducing side effects and prolonging the duration of sufentanil. METHODS One hundred six healthy pregnant women in labor were enrolled in this study, which was divided into four phases. In all phases, patients received a CSE anesthetic while in the lateral position. In phase I, three groups of six women each received intrathecal neostigmine, 5, 10, or 20 microg, in an open-label, dose-escalating safety assessment. In phase II, 24 women received intrathecal sufentanil alone to establish an ED50 (dose that produces > 60 min of labor analgesia in 50% of patients). In phase III, an ED50 was established for sufentanil combined with a fixed dose of neostigmine (10 microg). In phase IV, 40 women received either twice the ED50 of sufentanil alone or twice the ED50 of sufentanil plus neostigmine, 10 microg. RESULTS Neostigmine alone had no adverse effects on maternal vital signs, fetal heart rate, or Apgar scores. Neostigmine, 20 microg, produced analgesia in one patient and severe nausea and vomiting in another. The ED50 for intrathecal sufentanil alone was 4.1 +/- 0.31 microg, and the ED50 for intrathecal sufentanil combined with neostigmine, 10 microg, was 3.0 +/- 0.28 microg. The duration of analgesia and side effects from double these ED50s (sufentanil, 9 microg, or sufentanil, 6 microg, plus neostigmine, 10 microg) were similar between groups. CONCLUSIONS The 10-microg intrathecal neostigmine dose alone produced no analgesia or side effects, but reduced the ED50 of intrathecal sufentanil by approximately 25%. Additionally, doses approximately double these ED50s each produced a similar duration of analgesia and side effects, indicating intrathecal neostigmine shifts the dose-response curve for intrathecal sufentanil to the left.

Neostigmine combined with bupivacaine, clonidine, and sufentanil for spinal labor analgesia

We previously found that spinal clonidine prolongs labor analgesia when combined with spinal bupivacaine and sufentanil. We sought to determine whether the addition of spinal neostigmine to these drugs would further enhance labor analgesia. By use of a combined spinal/epidural technique, 36 patients were randomized to receive a hyperbaric spinal injection of bupivacaine 2.5 mg plus clonidine 50 &mgr;g and sufentanil 10 &mgr;g with or without neostigmine 10 &mgr;g. Pain, maternal hemodynamics, fetal heart rate, nausea, pruritus, sedation, motor block, sensory levels to pinprick, and maternal oxygen saturation were assessed at regularly specified intervals after spinal injection until additional analgesia was requested. The duration of spinal analgesia was similar between groups (215 ± 60 min in the Control group versus 205 ± 62 min in the Neostigmine group). Likewise, pain scores, the duration of labor, Apgar scores, and side effects were similar between groups except that patients administered neostigmine experienced significantly more nausea and vomiting (53% vs 7%, P = 0.01). We conclude that spinal neostigmine 10 &mgr;g produces severe nausea and does not potentiate the duration of spinal analgesia in laboring women from spinal bupivacaine, clonidine, and sufentanil.

Intravenous butorphanol, meperidine, and their combination relieve pain and distress in women in labor.

Background: Systemic opioids are commonly administered during labor, but their efficacy has been recently questioned. In addition, laboratory and clinical studies provide a strong rationale for combining &mgr;- and &kgr;-opioid receptor agonists for analgesia. The authors therefore studied, using validated intensity and affective scales and definitions of effective pain relief, the efficacy of intravenous meperidine, butorphanol, and their combination for labor analgesia. Methods: Healthy women with singleton term pregnancy requesting analgesia during active labor were studied. Women were randomly assigned to receive 50 mg meperidine, 1 mg butorphanol, or 25 mg meperidine plus 0.5 mg butorphanol (n = 15/group). Pain intensity was assessed using a 0–10 numerical rating scale, and affective magnitude was assessed using a ratiometric descriptive scale before drug administration and between the sixth and seventh uterine contractions after drug administration. Results: All three treatments reduced pain intensity equally. Butorphanol alone did not reduce pain affective magnitude, whereas the other treatments did. There was a significant correlation between reduction in pain intensity and affective magnitude in all groups, with greater reductions in affective magnitude than intensity. Overall, 29% of women exhibited clinically meaningful pain relief, with no difference among groups. Groups did not differ in incidence of opioid-induced adverse effects. Conclusions: These doses of meperidine and butorphanol do reduce pain intensity and affective magnitude, although a minority of patients achieve meaningful pain relief as defined in multiple patient populations, including laboring women. Combination of these drugs did not improve their therapeutic benefit.

Success of spinal and epidural labor analgesia: comparison of loss of resistance technique using air versus saline in combined spinal-epidural labor analgesia technique.

Background:Comparison of air versus saline for loss of resistance technique (LORT) in combined spinal epidural labor analgesia (CSE) has not been evaluated, and neither has the relation between CSE characteristics (the presence/absence of initial spontaneous clear fluid return or upon aspiration) and spinal/epidural analgesia outcomes. The authors hypothesized that there is no difference in the spinal analgesia success or epidural catheter efficacy between using air versus saline LORT for CSE. Methods:A total of 360 patients were randomized to air or saline LORT for CSE. Primary outcome was spinal analgesia success as defined by verbal pain score of no more than 3 at 15 min after spinal dose administration. Secondary outcomes were CSE characteristics, catheter replacement, and average hourly epidural drug consumption. Results:Results from 345 patients were analyzed. Spinal analgesia success, epidural catheter replacement, and drug consumption were not different between using air or saline LORT and were also independent of the presence/absence of fluid return on aspiration if initial spontaneous fluid returned to the spinal needle. However, epidural catheters inserted in absence of initial fluid return had a significantly higher catheter replacement rate (28.6%) than the 4.1% among those with initial fluid return (P < 0.03). Conclusions:Spinal analgesia success rate and epidural efficacy are independent of whether air or saline is used for LORT during CSE. Practice of aspiration for fluid after observing initial fluid return may be unnecessary because this practice does not alter spinal/epidural analgesia outcomes. However, epidural catheters inserted with the absence of initial fluid returned to spinal needle may pose a high failure risk.

The effect of light exercise upon blood flow velocity determined by laser-Doppler flowmetry

Primary objective: The dominant, 0.1 Hz frequency, Traube-Hering component of blood flow velocity, which is related to baroreflex activity, may be modulated through the established techniques of manipulative medicine. Light exercise programmes, appropriate for use by the elderly and collectively termed gymnastique douce, also are believed to impact the baroreflex in a positive manner. Our objective was to test the relationship between the Traube-Hering oscillation and light exercise. Methods: Using laser-Doppler flowmetry to quantify the Traube-Hering and other components of the blood flow velocity oscillation, we compared flowmetry records of 10 subjects before and immediately following a light-exercise programme. Results: The data show that the light exercise programme amplifies the 0.1 Hz component of the blood flowmetry record. Conclusions: The 0.1 Hz component of blood-flow velocity is physiologically linked to baroreflex activity. It is this component that is augmented by a light exercise programme.

Blood pressure, but not cerebrospinal fluid fentanyl concentration, predicts duration of labor analgesia from spinal fentanyl.

Background:There is a wide variability in dilution of drugs in cerebrospinal fluid after spinal injection, as measured near the site of injection. With local anesthetics, there is a wide variability in speed of onset, which correlates with block duration. The authors tested whether local cerebrospinal fluid drug concentrations and onset time would predict duration of analgesia from spinal fentanyl in laboring women. Methods:After written informed consent, fentanyl (50 &mgr;g) was injected using the combined spinal epidural method in 56 women requesting analgesia for labor. The stylet was reinserted in the spinal needle, and 60 s later, the cerebrospinal fluid was aspirated for fentanyl assay. Time to analgesia and duration of analgesia were recorded, and data were analyzed by linear regression. Results:Fifty-two women were included for data analysis. The cerebrospinal fluid fentanyl concentrations were 3.1 ± 5.9 &mgr;g/ml, with a 7-fold range (0.9–5.9 &mgr;g/ml). Fentanyl concentration did not correlate with onset, initial sensory level at 5 and 10 min, or duration of analgesia. Decreased diastolic and increased systolic blood pressure and lower parity, but not fentanyl concentrations, correlated with longer labor analgesia. The resultant model was predictive when applied to data from four previous studies of spinal opioid analgesia duration. Conclusions:Contrary to our hypothesis, the local concentration of fentanyl in the cerebrospinal fluid 1 min after injection was not correlated with onset or duration of labor analgesia. The unexpected but consistent relationship between blood pressure and combined spinal epidural analgesia duration suggests that resting hemodynamic state affects the distribution and/or clearance of intrathecally administered opioids.

Epidural Neostigmine versus Fentanyl to Decrease Bupivacaine Use in Patient-controlled Epidural Analgesia during Labor: A Randomized, Double-blind, Controlled Study

Background: The addition of opioids to epidural local anesthetic reduces local anesthetic consumption by 20% but at the expense of side effects and time spent for regulatory compliance paperwork. Epidural neostigmine also reduces local anesthetic use. The authors hypothesized that epidural bupivacaine with neostigmine would decrease total hourly bupivacaine use compared with epidural bupivacaine with fentanyl for patient-controlled epidural analgesia. Methods: A total of 215 American Society of Anesthesiologists physical status II, laboring parturients requesting labor epidural analgesia consented to the study and were randomized to receive 0.125% bupivacaine with the addition of either fentanyl (2 &mgr;g/ml) or neostigmine (2, 4, or 8 &mgr;g/ml). The primary outcome was total hourly local anesthetic consumption, defined as total patient-controlled epidural analgesia use and top-ups (expressed as milliliters of 0.125% bupivacaine) divided by the infusion duration. A priori analysis determined a group size of 35 was needed to have 80% power at &agr; = 0.05 to detect a 20% difference in the primary outcome. Results: Of 215 subjects consented, 151 patients were evaluable. Demographics, maternal and fetal outcomes, and labor characteristics were similar among groups. Total hourly local anesthetic consumption did not differ among groups (P = 0.55). The total median hourly bupivacaine consumption in the fentanyl group was 16.0 ml/h compared with 15.3, 14.6, and 16.2 ml/h in the 2, 4, and 8 &mgr;g/ml neostigmine groups, respectively (P = 0.55). Conclusions: The data do not support any difference in bupivacaine requirements for labor patient-controlled epidural analgesia whether patients receive epidural bupivacaine with 2 to 8 &mgr;g/ml neostigmine or epidural bupivacaine with 2 &mgr;g/ml fentanyl.

Association Between Cervical and Thoracic Somatic Dysfunction Among Second-Year Osteopathic Medical Students

CONTEXT The ubiquitous nature of cervical and thoracic somatic dysfunction requires osteopathic physicians to have a strong working knowledge of regional spinal mechanics and their functional and dysfunctional interrelationships. OBJECTIVE To determine whether cervical and thoracic somatic dysfunction occur concomitantly, particularly somatic dysfunction of the occipitoatlantal (OA) and upper thoracic (T1-T4) region of the spine. METHODS A retrospective analysis of cervical and thoracic somatic dysfunction prevalence diagnosed by faculty in second-year osteopathic medical students was conducted. Somatic dysfunction was defined as a vertebral unit possessing any of the following palpatory characteristics: tissue texture changes, asymmetry of motion and relative position, restriction of motion, or tenderness (ie, TART criteria). For each instance of somatic dysfunction diagnosed, the segmental level identifying the superior segment of the involved vertebral unit was recorded, as well as the spinal region (ie, cervical [OA, atlantoaxial (AA), and C2-C7] or thoracic [T1-T12]). Descriptive analyses, a Pearson χ(2) test, and a regression model using an analysis of variance were performed on the data. RESULTS Among 338 students included in the study, the following 5 vertebral segments were found to have the highest prevalence of somatic dysfunction: OA (257 [76.0%]), C3 (257 [76.0%]), T3 (247 [73.1%]), T5 (226 [66.9%]), and T4 (223 [66.0%]). A Pearson χ(2) test of association between the OA vertebral segment and the following segments were found to be statistically significant: AA (P=.024), C2 (P=.032), and T4 (P=.045). An analysis of variance revealed statistical significance between the prevalence of upper cervical (OA, AA, C2) somatic dysfunction and the prevalence of upper thoracic (P<.001) and midthoracic (T5-T8) (P<.001) somatic dysfunction; the prevalence of lower cervical (C3-C7) (P=.74) and lower thoracic (T9-T12) (P=.085) somatic dysfunction was not found to be significant. CONCLUSION A statistically significant association between cervical somatic dysfunction and thoracic somatic dysfunction was confirmed. In addition, there was a statistically significant association between dysfunction of the OA and the AA, C2, and T4 vertebral segments. These results suggest that the number of dysfunctional vertebral segments in the upper thoracic and midthoracic spinal regions is directly proportional to the number of dysfunctional segments found in the upper cervical spinal region.