Analgesia for labour
Parry MG, Fernando R, Bawa GPS, et al [Royal Free Hosp, London]
Dorsal Column Function After Epidural and Spinal Blockade :Implications for the Safety of Walking Low-Dose Regional Analgesia for Labour
Anaesthesia 53: 382-403, 1998
Introducion – Parturients are able to walk during labor with the maintenance of lower limb motor power after both low-dose epidural and combined spinal/epidural analgesia. The effects of such low-dose regional analgesic regimens on dorsal column somatosensory function have raised some controversy. A previous study concluded that walking after low-dose epidural analgesia was unsafe because of a potential increased risk of falling. This was reexamined, determined whether dorsal column function is impaired after regional blockade for labor using low-dose combinations of bupivacaine and fentanyl. For these thirty parturients received low-dose epidural analgesia, 30 parturients received low-dose spinal blockade, and 30 received spinal anesthesia for elective cesarean section using a larger total dose of local anaesthetic. A clinical assessment of lower-limb proprioception and vibration sense was performed after anesthesia was administered. Then before allowing patients to walk after low-dose regional techniques for labor, assessment of lower-limb motor power and dorsal column function is recommended. In the majority of parturients receiving low-dose epidural and combined spinal/epidural or intrathecal injection. However, the effects on dorsal column function of prolonged intermittent low-dose epidural boluses or infusions are uncertain.
Supervised ambulation may be safe for mothers receiving intrathecal or epidural opioid analgesia [with or without very small doses of local anesthetic], provided the mother retains adequate motor function, proprioception, and balance. Unfortunately, there are no reliable tests that predict who may ambulate safely. Further, some patients may have postural hypotension. Therefore, these patients should ambulate only with assistance.
James KS, McGrady E, Quasim I, et al Glasgow Royal Maternity Hosp, Scotland]
Comparison of Epidural Bolus Administration of 0.25% Bupivacaine and 0.1% Bupivacaine with 0.0002% Fentanyl for Analgesia During Labour
Br J Anaesth 81: 507-510, 1998
Objective – Because as many as 85% of patients have motor block when local anesthetic agents alone are used to achieve epidural analgesia, a “mobile” epidural using a combined spinal-epidural technique was developed, which enables almost 50% of women to get out of bed during labor. A mobile epidural using 0.1% bupivacaine and 0.0002% fentanyl was compared in a double-blind, randomized study with a conventional epidural using 0.25% bupivacaine throughout labor.
It was found that epidural administration of 0.1% bupivacaine with 2 mg/mL of fentanyl resulted in a significantly lower incidence of motor block in laboring women, shortened the second stage of labor, and resulted in fewer instrument deliveries than did epidural administration of 0.25% bupivacaine.
Editorial comment by Dr. D.H. Chestnut – The addition of an opioid to the local anesthetic allows the anesthesiologist to give a more dilute solution of local anesthetic when providing epidural analgesia in laboring women. This results in less motor block, and intuitively it seems likely that this should result in a decreased requirement for instrumental vaginal delivery. This study confirms the results of retrospective studies, namely that epidural administration of more dilute solution of local anesthetic results in less motor block and fewer instrumental vaginal deliveries than epidural administration of a more concentrated solution of local anesthetic.
Gaiser RR, Cheek TG, Gutsche BB, [Univ of Pennsylvania, Philadelphia]
Comparison of Three Different Doses of Intrathecal Fentanyl and Sufentanil for labor Analgesia
J Clin Anesth 10: 488-493, 1998
Objective – Intravenously administered sufentanil is 5 to 10 times more potent than fentanyl but has a shorter elimination half-life. Dose-response results of the effect of intrathecal administration of these 2 opioids have not been conducted. The duration of analgesia and the incidence of side effects of these 2 opioids were compared when they were administered intrathecally at different doses to patients in labor.
Methods – In a randomized, double-blind, study either 25, 37.5 or 50 mg of fentanyl or 5, 10 or 15 mg of sufentanil diluted to a volume of 1.5 mL with normal saline was administered intrathecally to 60 laboring women. Duration of analgesia, contraction pain, degree of pruritus, maternal blood pressure and heart rate, fetal heart rate, Apgar scores, Neurologic and Adaptive Capacity [NAC] scores at 15 minutes and 2 hours, and umbilical arterial and venous pH were recorded.
Results – Five patients were excluded from the analysis. Duration of analgesia differed for doses of sufentanil only. Durations of analgesia were significantly longer for all doses of sufentanil than for all doses of fentanyl. Maximum pruritus scores were similar for all doses of both opioids. Although there was no difference in duration of pruritus among all doses of either opioid, the duration of pruritus was significantly longer for sufentanil. There was significant effect on either systolic or diastolic blood pressure.
Conclusion – Durations of analgesia and of pruritus were significantly longer at all doses of intrathecal sufentanil.
Editorial comments – This study suggests that there is no benefit to giving an intrathecal dose of fentanyl larger than 25 mg and there is no benefit to giving an intrathecal dose of sufentanil larger than 5 mg in laboring women. The duration of intrathecal sufentanil analgesia is approximately 30 minutes longer than intrathecal fentanyl analgesia, but sufentanil results in a longer duration of pruritus.
Morley -Forster PK, Weberpals J [Univ of Western Ont, London]
Neonatal Effects of Patient-Controlled Analgesia Using Fentanyl in Labor
Int J Obstet Anesth 7: 103-107, 1998
Objective – Whereas the value of patient-controlled analgesia [PCA] with fentanyl for women in labor has been established, there are no studies evaluating neonatal safety of PCA with fentanyl. The effects of maternal PCA with fentanyl on infants of greater than 32 weeks gestational age were retrospectively examined.
Methods – Records of all 31 women in labor using PCA with fentanyl between 1992 and 1994 and delivering live infants of greater than 32 weeks’ gestational age were reviewed and it was found that the use of PCA with fentanyl in laboring women can result in neonatal depression. The safety and efficacy of short-acting opioids during labor should be determined in a prospective study.
Editorial Comments – This study illustrates the limitations of intravenous PCA with fentanyl during labor. Doses that result in satisfactory analgesia- especially during advanced labor- cause maternal sedation and a high incidence of neonatal respiratory depression. The authors suggest that alfentanil might be superior to fentanyl when providing intravenous PCA during labor. However, this represents speculation, given that a prospective study of intravenous PCA with alfentanil has not been performed in laboring women.
Butler R, Fuller J [ London Health Sciences Centre, Ont; St Joseph’s Health Centre, London, Ont]
Back Pain Following Epidural Anaesthesia in Labour
Can J Anaesth 45: 724-728, 1998
Background – Prospective studies have not confirmed the reported association between epidural anesthesia and postpartum back pain. The specific risk factors for postpartum back pain remain unclear and knowledge of them is needed to clarify the mechanism and to assess patient risk. Factors associated with the development of postpartum back pain in women receiving epidural analgesia were analyzed.
Methods – The prospective, observational study included 300 women who were planning to have epidural anesthesia for labor and delivery. Background information collected from patients, and obstetric and anesthetic data were collected from hospital records.
It was found that postpartum back pain is common among women receiving epidural anesthesia for labor and delivery, but does not last long for most patients, who have only a dull ache around the insertion site, lasting a few days. Pain lasting longer than 2 weeks is more likely for women with a previous history of back pain, and less likely for nulliparous women.
Editorial comments – Recent prospective studies suggest that administration of epidural analgesia during labor does not cause prolonged postpartum back pain. The present article suggests that transient postpartum back pain is common among women who received epidural analgesia during labor, but that persistent back pain is uncommon. A history of back pain was associated with occurrence of some postpartum back pain but was not predictive of postpartum back pain lasting more than 14 days.
Shapiro A, Fredman B, Zohar E, et al [ Meir Hosp, Kfar Saba, Israel; Tel Aviv Univ, Israel]
Alternating Patient Position Following the Induction of Obstetric Epidural Analgesia Does not Affect Local Anaesthetic Spread
Int J Obstet Anesth 7 : 153-156, 1998
Objective – It is not known whether altering the position of laboring women improves symmetric sensory blockade. The influence of changing the patient’s position on the height and symmetry of blockade during the initial stages of epidural analgesia was investigated in a prospective, randomized, single blind study in laboring women.
Methods – Epidural Injections were administered to 20 laboring women in the supine position with a 15 to 20-degree right flank elevation [group S], 20 women in the left lateral position for 10 minutes after injection [Group L], and 20 women in the left lateral position for 5 minutes and then the right lateral position for 5 minutes [group L + R]. Then all women assumed the supine position with a 15 – to 20-degree right flank elevation. Loss of pinkprick and temperature sensation and pain scores assessed 10 minutes after injection with 50 g fentanyl in 10 ml of 0.125% bupivacaine.
Results – Time to maximum block, height of sensory deficit, and Visual Analog Scores were similar for all groups. Pain at maximum blockade was significantly less than at baseline for all groups.
Editorial comments – This study supports other studies that have demonstrated that the patient’s position or posture has little effect on the efficacy of epidural analgesia in laboring women. A malpositioned cather is more likely responsible for unilateral blockade.
Schorr SJ, Speights SE, Ross EL, et al [ Univ of Mississippi, Jackson]
A Randomized Trial of Epidural Anesthesia to Improve External Cephalic Version Success
Am J Obstet Gynecol 177 : 1133- 1137, 1997
Purpose – Several approaches have been tried to improve the success rate of external cephalic version in pregnancies with breech presentation. A recent retrospective study suggested that regional anesthesia improved the success of external cephalic version with no increase in fetal or maternal morbidity. This prospective study evaluated the use of epidural anesthesia for external cephalic version.
Methods – The randomized trial included 9 women at more than 37 weeks’ gestation with breech presentation who were scheduled for external cephalic version. One group of women received epidural anesthesia, and the other did not. Version was performed under ultrasound guidance, with up to 3 attempts made.
Results – The 2 groups were similar in terms of maternal age, parity, and weight; gestational age; estimated fetal weight; and station of the presenting part. External cephalic version was successful in 69% of women receiving epidural anesthesia compared with 32% of the control group.
Editorial Comments – In the past, some obstetricians have expressed concern that administration of analgesia/ anesthesia may allow an increased risk of excessive force during external cephalic version, which might result in an increased risk of adverse outcome. These obstetricians contend that the absence of analgesia/anesthesia requires the obstetrician to be gentle and avoid excessive force. In the present study, the authors demonstrated and 2-fold increase in the incidence of successful external cephalic version in the epidural analgesia group. The authors did not compare neonatal outcome in the 2 groups.,but they stated that ” there were no cases of fetal distress or abruptio placentae” in either group. The authors performed real-time ultrasonography to monitor the fetal heart rate during the procedure, which likely enhances the safety of this procedure.
Colonna – Romano P, Nagaraj L [ Allegheny Univ, Philadelphia]
Tests to Evaluate Intravenous Placement of Epidural Catheters in Laboring Women : A Prospective Clinical Study
Anesth Analg 86: 985-988, 1998
Objective – The accuracy of an epinephrine- containing epidural test dose [ EpiTD] to identify the unintentional cannulation of an epidural vessel was evaluated in a large prospective clinical study in women in active labor.
Methods – A lumbar epidural catheter was placed in each of 209 unmedicated women in active labor and aspirated. If blood or CSF was detected, the catheter was replaced. Fetal heart rate was monitored by ultrasonography, and uterine activity with a tocodynamometer. Each patient was given an EpiTD [ 15 g epinephrine plus 45 mg lidocaine] and observed for a tachycardic response. If the tachycardic response was absent or equivocal, the EpiTD and catheter aspiration were repeated. Patients with negative EpiTD and negative aspiration were given 0.25% bupivacaine [6-12 mL] with or without fentanyl [ 50 g]. Absence of analgesia within 20 minutges was defined as a failed block. Patients with a second test dose [Lido100TD], which was defined as positive if tinnitus or a metallic taste appeared.
Conclusions- The EpiTD is a reliable way to test proper placement of epidural catheters in women in labor. With a sensitivity of 100%, specificity of 96%, negative predictive value again of 100% , and positive predictive value of EpiTD 63% respectively.