Cyclic AMP and Segmental Epidural Analgesia During Labour

The blood cyclic AMP level was determined just before, during and after induced labour in 27 healthy women. To achieve complete pain relief during the first stage of labour, 14 of them were given segmental epidural analgesia at the height of Th 10-12. The remaining parturients served as controls. Cyclic AMP was above the normal non-gravid level before induction in both groups. In the control group the cyclic AMP content decreased during the first stage of labour, then it increased and reached a peak at the moment of delivery. These changes were, however, not significant. In the epidural group the cyclic AMP level rose significantly during the first stage, and also reached its peak at the moment of delivery. There was a statistically significant difference between the groups at a cervical dilatation of 6-8 cm. After delivery the cyclic AMP rapidly declined to its initial value in both groups. The possible role of the decreased uterine contractions after the block in the increase of the cyclic AMP is discussed.     

Segmental Epidural Analgesia and Urinary Excretion of Catecholamines during Labour

Urinary excretion of catecholamines was determined separately during the first stage of labour and during the period from the beginning of the second stage until 1/2 h after delivery in 16 healthy mothers, whose labours were induced at term. Seven mothers were given segmental epidural analgesia, at the height of Th_10–12, to achieve complete pain relief during the first stage of labour. The remaining parturients served as controls. During the first stage of labour the urinary excretion rate of catecholamines was at the normal nongravid rest level in both groups. During the second stage, and 1/2 h after the delivery, the amount of urinary catecholamines increased significantly in both groups. The latter values corresponded to the amounts of catecholamines excreted during heavy physical work.     

Epidural Administration of Neostigmine and Clonidine to Induce Labor Analgesia: Evaluation of Efficacy and Local Anesthetic-sparing Effect

Background: Epidural clonidine produces analgesia without motor impairment, and is associated with a local anesthetic-sparing effect during labor. The authors have recently demonstrated that epidural neostigmine initiates selective labor analgesia devoid of adverse effects. Both drugs possess common analgesic mechanisms mediated through spinal acetylcholine release. This study evaluates their epidural combination in parturients.

Methods: At the beginning of labor, parturients were randomly allocated to one of five groups to receive one of the following after a test dose: 150 [mu]g epidural clonidine, 750 [mu]g neostigmine, or 75 [mu]g clonidine combined with 250, 500, or 750 [mu]g neostigmine. A pain score (visual analog scale, 0-100) was recorded before administration and at regular intervals until request for a supplemental injection. Subsequent analgesia was provided by continuous epidural infusion of ropivacaine.

Results: Parturients did not differ regarding demographic data and initial pain score. Clonidine 150 [mu]g, neostigmine 750 [mu]g, and 75 [mu]g clonidine plus 250 [mu]g neostigmine produced ineffective and short-lasting effects. Clonidine 75 [mu]g plus 500 [mu]g neostigmine and 75 [mu]g clonidine plus 750 [mu]g neostigmine presented comparable durations of 90 +/- 32 and 108 +/- 38 min (mean +/- SD), respectively, and final analgesic efficacies, with 72.2% and 84%, respectively, of the parturients reporting a visual analog scale score of less than 30 out of 100 after 30 min. Ropivacaine use was significantly reduced in all clonidine groups (average, 9.5 mg/h) in comparison with neostigmine alone (17 +/- 3 mg/h). No adverse effects were observed for 75 [mu]g clonidine combined with any dose of neostigmine while maternal sedation (20%) and hypotension (33%) occurred with 150 [mu]g clonidine alone.     

Combinations of Bupivacaine, Fentanyl, and Clonidine for Lumbar Epidural Postoperative Analgesia: A Novel Optimization Procedure

Background: The authors developed and applied a method to optimize the combination of bupivacaine, fentanyl, and clonidine for continuous postoperative lumbar epidural analgesia.

Methods: One hundred eighteen patients undergoing knee or hip surgery participated in the study. Postoperative epidural analgesia during 48 h after surgery was optimized under restrictions dictated by side effects. Initially, eight combinations of bupivacaine, fentanyl, and clonidine (expressed as drug concentration in the solution administered) were empirically chosen and investigated. To determine subsequent combinations, an optimization model was applied until three consecutive steps showed no decrease in pain score. For the first time in a clinical investigation, a regression model was applied when the optimization procedure led to combinations associated with unacceptable side effects.

Results: The authors analyzed 12 combinations with an allowed bupivacaine concentration range of 0-2.5 mg/ml, a fentanyl concentration range of 0-5 [mu]g/ml, and a clonidine concentration range of 0-5 [mu]g/ml. The best combinations of bupivacaine, fentanyl, and clonidine concentrations were 1.0 mg/ml-1.4 [mu]g/ml-0.5 [mu]g/ml, 0.9 mg/ml-3.0 [mu]g/ml-0.3 [mu]g/ml, 0.6 mg/ml-2.5 [mu]g/ml-0.8 [mu]g/ml, and 1.0 mg/ml-2.4 [mu]g/ml-1.0 [mu]g/ml, respectively, all producing a similarly low pain score. The incidence of side effects was low. The application of the regression model to combinations associated with high incidence of motor block successfully directed the optimization procedure to combinations within the therapeutic range.     

Lumbar Epidural Morphine in Humans and Supraspinal Analgesia to Experimental Heat Pain

Background: Epidural administration of morphine is a common analgesic technique to manage pain. Morphine spreads from the epidural space to the cerebrospinal fluid and then rostrally, causing side effects mediated by the brain stem. However, data on the rostral spread of morphine-mediated analgesia are sparse. This study examined the rostral spread of analgesic effects on heat and electrical pain after epidural administration of morphine.

Methods: In a randomized, double-blinded, placebo-controlled, crossover study, 5 mg morphine or saline placebo were injected into the lumbar epidural space in nine healthy volunteers. Correct needle placement was confirmed with fluoroscopy. Analgesia to experimental nociceptive heat and electrical stimuli was measured at lumbar (L4), thoracic (T10), cervical (C2), and trigeminal (V2) levels before and 2, 5, 10, and 24 h after epidural injection. Plasma samples for assaying morphine concentrations were drawn before and after each analgesic evaluation.

Results: Epidural morphine significantly attenuated experimental heat pain at all dermatomes tested compared with saline placebo. Analgesic effects were significant at L4 after 2, 5, and 10 h, at T10 after 5, 10, and 24 h, and at V2 after 10 h. Electrical pain was attenuated at the lumbar and thoracic but not at the cervical dermatome. Analgesic effects were significant at L4 after 2, 5, and 10 h and at T10 after 5 and 10 h. Morphine plasma concentrations were below the detection limit (1 ng/ml) in eight of the nine subjects 10 h after epidural injection.     

Experimental Cutaneous Pain Thresholds and Tolerance in Clinical Analgesia with Epidural Morphine

Ten patients experiencing significant analgesia from repealed low-dose morphine injections via an indwelling epidural catheter were studied. One group (n=5) with acute, postoperative pain was tested for changes in experimental cutaneous pain thresholds with and without clinical morphine analgesia. Three of these patients received intravenous naloxone. The analgesia was reversed in two. There was no significant alteration in any cutaneous modality, including pain, although the postoperative deep pain was relieved. This discrepancy might be explained by the existence of separate subpopulations of opiate receptors at the spinal cord level, which differentiate nociceptive input from the skin and from deep body structures. The other group (n = 5) of cancer pain patients with a permanent epidural catheter was monitored for long-term changes in clinical pain. Signs of tolerance were not seen with an observation period up to 6 weeks.     

不同穿刺点硬膜外镇痛分娩效果比较

目的探讨不同穿刺点硬膜外镇痛分娩的效果。方法将 12 0例单胎足月初产妇随机分为两组各 6 0例。观察组以L1～L2 为穿刺间隙 ,对照组为L3 ～L4。两组镇痛方法、所用药物及浓度相同。观察两组镇痛药首剂量、起效时间 ,PCA次数 ,VAS评分 ,运动神经阻滞评分 ,第一、二产程时间 ,分娩方式 ,新生儿Apgar评分 ,产后 2h出血量等指标。结果VAS评分、运动神经阻滞程度、新生儿Apgar评分、产后 2h出血量两组比较 ,差异无显著性意义(均P >0 .0 5 ) ;其余项观察组均优于对照组 (均P <0 .0 5 )。结论L1～L2 间隙穿刺硬膜外镇痛分娩 ,有良好的镇痛效果 ,可缩短产程 ,提高自然分娩率。     

Effect of Segmental Epidural Analgesia upon the Uterine Activity with Special Reference to the Use of Different Local Anaesthetic Agents

Segmental epidural block was given to 60 primiparous women during vaginal delivery, and the effect of the block on the uterine activity was studied after the first epidural injection. The women were divided into two main groups, according to whether or not oxytocin was used for stimulating the uterine contractions, and three different local anaesthetics--lidocaine-adrenaline, bupivacaine-adrenaline and plain bupivacaine--were tested. There was a transitory decrease in uterine activity in all women after the block was applied. In women with normal uterine activity before the block, a return to almost pre-analgesic values was noted within 30 min after the block, whereas in women treated with oxytocin there was still a reduction of 15-17% at this time. The reduction was caused by a decreasing intensity and at the same time an increase in the variability of the intensity, manifested as an increase in the coefficient of variation for this variable. There were no significant differences between the local anaesthetic agents tested, but addition of adrenaline to the bupivacaine solution resulted in a more marked decrease in uterine activity in women treated with oxytocin.     

可乐定对兔利多卡因硬膜外麻醉效果及药物浓度影响的实验研究

本文评价了兔利多卡因硬膜外麻醉时，可乐定对阻滞效果和利多卡因血药浓度的影响。１８只白兔随机分为利多卡因对照组（１组）、肾上腺素组（２组）和可乐定组（３组）。采用盲法硬膜外分别注射上述三组药物。结果显示，可乐定能延长感觉和运动阻滞时间，降低血清利多卡因水平。其作用类似于肾上腺素，可能是可乐定通过作用于脊髓肾上腺素能受体发挥镇痛效应和／或发挥α２受体介导的缩血管作用。     

Effects of Epidural Analgesia on Plasma Catecholamines and Cortisol in Parturition

To assess the effect of epidural block on plasma catecholamines and cortisol during labour and delivery, plasma epinephrine, norepinephrine and cortisol levels were determined in 26 healthy parturients, all of whom delivered vaginally (18 received an epidural block, eight had meperidine 50 mg intramuscularly). We found a significant drop of plasma epinephrine and cortisol and no significant reduction of plasma norepinephrine 1 h after administration of epidural block compared to preblock values. Observing the data during the whole course of labour in correlation with cervical dilatation, in the control group, where the parturients received meperidine, all hormones rose progressively up to the moment of delivery. One hour after delivery the catecholamines returned to normal levels; cortisol returned more slowly. In the epidural group the increase of plasma epinephrine and cortisol was significantly inhibited but not that of norepinephrine.     

小儿术后硬膜外自控镇痛的临床效果

目的：探讨小儿术后硬膜外自控镇痛（ＰＣＥＡ）的可行性和安全性。方法;术后５￣１１岁的小儿４０例,分成Ａ、Ｂ两组。Ａ组镇痛液配方０．０７５％布比卡因＋０．００１２％丁丙诺啡,Ｂ组配方与Ｓ组相同并加入小剂量氟哌啶,以ＬＣＰ模式实施ＰＣＥＡ。结果：Ｂ组２天用量均少于Ａ组（Ｐ〈０．０１￣０．０５）,从三种评分指标和并发症综合比较分析,提示两组均能达到满意的镇痛效果,但Ｂ组优于Ａ组。结论：小儿术后用０．０７     

Long-term Pain and Activity during Recovery from Major Thoracotomy Using Thoracic Epidural Analgesia

Background: Pain following thoracotomy can persist for years with an undetermined impact on quality of life. Factors hypothesized to modulate this painful experience include analgesic regimen, gender, and type of incision.

Methods: A total of 157 generally healthy patients of both genders scheduled for segmentectomy, lobectomy, or bilobectomy through a posterolateral or muscle-sparing incision were randomly assigned to receive thoracic epidural analgesia initiated prior to incision or at the time of rib approximation. Pain and activity scores were obtained 4, 8, 12, 24, 36, and 48 weeks after surgery.

Results: Overall, there were no differences in pain scores between the control and intervention groups during hospitalization (P >= 0.165) or after discharge (P >= 0.098). The number of patients reporting pain 1 yr following surgery (18 of 85; 21.2%) was not significantly different (P = 0.122) from the number reporting preoperative pain (15 of 120; 12.5%). During hospitalization, women reported greater pain than men (worst pain, P = 0.007; average pain, P = 0.016). Women experienced fewer supraventricular tachydysrhythmias (P = 0.013) and were thus discharged earlier (P = 0.002). After discharge women continued to report greater discomfort than men (P <= 0.016), but did not differ from men in their level of physical activity (P = 0.241).     

硬膜外麻醉对剖宫产应激反应的影响

对硬膜外麻醉下剖宫产时应激反应进行了研究，通过测定β－内啡肽、强啡肽、皮质醇加压药及生长素，说明硬膜外麻醉可以抑制这类下腹部手术的应激应用。