Failure of epidural morphine to relieve pain in labour

Maternal pain and anxiety in genetic amniocentesis: expectation versus reality

OBJECTIVE

To investigate maternal perceptions of both pain and anxiety before and after genetic amniocentesis.

STUDY DESIGN

This prospective study of midtrimester, singleton pregnancies was conducted between March 2000 and July 2000. Study variables included patient demographics, medical and obstetric histories, indication for amniocentesis and a description of the source of information used by the patient regarding the procedure and technical degree of difficulty. Maternal pain and anxiety associated with performing amniocentesis were subjectively quantified with the use of the visual analog scale (VAS). Statistical analysis included Wilcoxon signed rank test, anova, and simple and stepwise regression analyses.

RESULTS

One hundred and eighty-three women participated in the study. Perception of pain before amniocentesis was significantly higher compared to that expressed immediately after the procedure, with a mean VAS score of 3.7 +/- 2.5 vs. 2.1 +/- 2.0 (P < 0.0001). Similarly, perception of anxiety was significantly greater prior to the procedure, with a mean VAS score of 4.6 +/- 2.8 vs. 2.8 +/- 2.4 after the amniocentesis (P < 0.0001). Perceptions of pain and anxiety were significantly and positively correlated to each other both before and after the procedure (P < 0.0001). History of a prior amniocentesis was the only variable associated with reducing expected pain and anxiety (negative correlation, P < 0.001), whereas the technical degree of difficulty was the only significant variable impacting on the actual pain and anxiety (positive correlation, P < 0.005).

CONCLUSIONS

Preamniocentesis counseling should emphasize the fact that, for most women, the actual pain and anxiety experienced during the procedure are significantly lower than expected. In fact, on a scale of 0-10, the mean level of pain was only 2.1, with a slightly higher mean level of anxiety.

Analgesic efficacy of intravenous morphine in labour pain: a reappraisal

The aim of the present study was to investigate the dose-related analgesic effect of intravenous (i.v.) morphine during spontaneous term first stage labour. This was an open study in 17 parturients who requested analgesia for severe labour pain. All women were given morphine i.v. in repeated doses of 0.05 mg/kg following every third contraction until a final dose of 0.20 mg/kg was reached. The decrease in overall pain intensity, from median visual analogue scale (VAS) 85 (range 52-100) to median VAS 70 (range 46-99), was clinically insignificant. The number of women experiencing back pain, however, decreased significantly following morphine. The most striking effect of morphine (7.2-18 mg) was pronounced sedation. No adverse reactions related to morphine were noted in the neonates. We conclude that i.v. morphine does not significantly reduce overall labour pain intensity. Thus, if a real analgesic effect is desired, systemically given morphine seems inappropriate and other techniques should be used.

Fentanyl: clinical use as postoperative analgesic--epidural/intrathecal route

The administration of epidural and intrathecal opioids for the management of postoperative pain is well established. Fentanyl, because of its greater lipophilicity, offers a number of advantages over morphine for epidural analgesia, including a lower incidence of side effects and reduced risk of delayed-onset respiratory depression. The relatively short duration of action of epidural fentanyl makes this agent more ideally suited for continuous infusion or patient-controlled epidural analgesia (PCEA). The effective doses and adverse effects profile of epidural fentanyl are reasonably well understood. Because of the lack of spread through the cerebrospinal fluid (CSF) and hence the segmental nature of the analgesia achieved, location of epidural catheter placement is of paramount importance when this agent is used. Prolonged epidural infusion of fentanyl may result in high systemic concentrations not dissimilar to IV infusion, and, therefore, the greatest efficacy of epidural fentanyl administration may be in combination with low concentrations of bupivacaine, an approach that achieves a synergistic effect. 2-Chloroprocaine has been shown to antagonize epidural fentanyl analgesia. Intrathecal fentanyl for postoperative analgesia is limited by its short duration of action with single-bolus administration. The widespread international increase in the use of epidural fentanyl for postoperative analgesia promises further improvements and refinement in techniques.

Bupivacaine versus bupivacaine plus fentanyl for epidural analgesia: effect on maternal satisfaction

OBJECTIVE

To compare a combination of epidural fentanyl and bupivacaine with bupivacaine alone for epidural analgesia in labour and to evaluate factors in addition to analgesia that may influence maternal satisfaction.

DESIGN

A prospective randomised pilot study.

SETTING

Birmingham Maternity Hospital.

SUBJECTS

85 primiparous women who requested epidural analgesia in labour and their babies.

INTERVENTIONS

Group 1 mothers were treated with bupivacaine conventionally, group 2 mothers with bupivacaine and fentanyl in a more complex way designed to provide satisfactory analgesia but with less troublesome side effects.

MAIN OUTCOME MEASURES

Overall maternal satisfaction, maternal perception of epidural analgesia and its side effects, and aspects of mothers' psychological states during labour, quantified using 100 mm visual linear analogue scales; the frequency of normal and operative deliveries; and measurements of neonatal wellbeing.

RESULTS

Satisfaction was higher in group 2 mothers (median group difference +3 mm, 95% confidence interval +1 to +5, p = 0.012): this was associated with more normal deliveries (difference between proportions 0.23, 95% confidence interval +0.03 to +0.42); greater self control (median group difference -7 mm, -17 to -2, p = 0.003); and reduced unpleasantness of motor blockade (-10 mm, -19 to -5, p less than 0.001), sensory blockade (-5 mm, -11 to -2, p = 0.002) and shivering (-5 mm, -18 to 0, p = 0.046) at the expense of mild itching (0 mm, 0 to 0, p less than 0.001). Group 1 mothers found restricted movements more unpleasant (-1 mm, -11 to 0, p = 0.006) and were more sleepy (-4 mm, -20 to 0, p = 0.032). The addition of fentanyl to bupivacaine reduced the requirement for local anaesthetic (-33 mg, -55 to -15, p less than 0.001) without compromising analgesia. No adverse effects in neonates were attributed to the use of fentanyl.

CONCLUSIONS

The already high maternal satisfaction from conventional epidural analgesia can be improved; epidural fentanyl may be combined with bupivacaine to reduce operative deliveries and confer other advantages that may increase maternal satisfaction. Further investigations should be performed to determine the exact mechanisms of these findings and, in particular, to develop a safe method of delivering such analgesia to women.

Epidural infusion of diamorphine with bupivacaine in labour. A comparison with fentanyl and bupivacaine

We have compared the analgesic effects of three epidural infusions in a randomised, double-blind study of 61 mothers in labour. An initial dose of bupivacaine 0.5% 8 ml was followed by either bupivacaine 0.125%, bupivacaine 0.125% with diamorphine 0.0025% or bupivacaine 0.125% with fentanyl 0.0002%. All infusions were run at a rate of 7.5 ml/hour. Analgesia was significantly better in both the groups receiving opioids. Diamorphine was shown to be the more effective supplement to bupivacaine. The 5% incidence of pruritus in the opioid groups was less than that reported by earlier authors.

Obstetric epidural analgesia with mixtures of bupivacaine, adrenaline and fentanyl

We performed a double-blind comparison of six solutions for epidural analgesia in 90 healthy Chinese women with uncomplicated pregnancies. Patients were randomly allocated to receive 10 ml bupivacaine 0.125% or 0.25% plain, bupivacaine 0.125% with adrenaline 1.25 micrograms/ml, bupivacaine 0.25% with adrenaline 2.5 micrograms/ml or the latter two solutions with added fentanyl 50 micrograms. Analgesia was unsatisfactory in 30% of the bupivacaine 0.125% groups without fentanyl. The addition of adrenaline, compared with bupivacaine 0.25% plain, gave faster onset and longer duration of analgesia (p less than 0.05) which was similar to that found in both fentanyl groups. There were no differences in method of delivery or neonatal Apgar scores among groups. The least concentrated mixture that gave the best analgesia was the combination of bupivacaine 0.125% with adrenaline 1.25 micrograms/ml and fentanyl 50 micrograms.

The addition of fentanyl to epidural bupivacaine in first stage labour

Epidural analgesia was studied in 100 healthy Chinese women with uncomplicated pregnancies in first stage labour. Patients were randomly allocated to receive 8 ml of one of the following five solutions: bupivacaine 0.125% with fentanyl 50 micrograms or fentanyl 100 micrograms, bupivacaine 0.25% plain, bupivacaine 0.25% with fentanyl 50 micrograms or fentanyl 100 micrograms. There was no difference in quality of analgesia among groups as measured by the reduction of visual analogue pain scores 20 minutes after the epidural dose. The duration of analgesia was similar among groups with the overall median duration being 105 minutes. There was no difference in method of delivery or neonatal Apgar scores. The least concentrated mixture providing good quality analgesia for the first stage of labour was the combination of bupivacaine 0.125% with fentanyl 50 micrograms.

Spinal opioids in the management of obstetric pain

Spinal opioids have become increasingly popular agents for providing analgesia during labor, augmenting anesthesia during cesarean section, and providing pain relief after operative delivery. The development of spinal opioids in the management of obstetric pain is reviewed.

Epidural diamorphine and bupivacaine in labour

A double-blind randomised study was performed to assess the analgesic effect of epidural diamorphine, administered with bupivacaine, on primigravid women in labour. Fifty patients received 0.25% bupivacaine 10 ml via the epidural catheter as their initial dose; patients in Group 1 received diamorphine 5 mg with the bupivacaine. A 0.1% bupivacaine infusion was started at 10 minutes and bolus doses of bupivacaine were given if required. There was a significant reduction in rate of bupivacaine administration, pain scores at 20 and 30 minutes, number of supplements required, and degree of motor blockade in the diamorphine group.

Epidural fentanyl and perineal pain in labour

Perineal pain during the course of routine epidural analgesia with bupivacaine was treated with a 10-ml top-up of either bupivacaine 25 mg, fentanyl 100 micrograms or fentanyl 100 micrograms plus bupivacaine 10 mg, in 46 women in the first stage of labour. Only fentanyl plus bupivacaine produced consistently reliable analgesia which was quicker in onset and longer in duration (140, SD 26 minutes) than either fentanyl (114, SD 26 minutes) or bupivacaine (99, SD 44 minutes) alone. Side effects, itching and drowsiness, which were not troublesome, were more frequent in the groups given fentanyl.

[Use of epidural and intrathecal opiates in obstetrics]

The discovery of opiate receptors and naturally occurring opiate-like substances in the central nervous system started a new era in pain control. Epidural and spinal opiates have been increasingly used since 1979. However, applying these analgesic techniques in obstetrics has been criticized because of possible side-effects on the mother and foetus. In this literature survey, their advantages and disadvantages are analyzed. Maternal side-effects include pruritus, nausea, urinary retention, and, most of all, respiratory depression. As a general rule, these side-effects are greater with the intrathecal route, high doses, and the use of morphine. The effects on the course of labour are small, and neonatal status is not altered. Spinal and epidural opiates are efficient analgesic techniques for labour and caesarean section. They provide a dose-related, but not surgical, analgesia. Currently, there is a great deal of interest in mixtures of a diluted local anaesthetic agent and a lipophilic drug for use during labour or caesarean section. An opiate alone may not consistently provide satisfactory analgesia during labour, and it cannot be recommended for routine use, except for patients in whom the cardiovascular effects of routine regional anaesthesia are to be avoided. The choice of a lipid-soluble opiate like fentanyl is safe. However, when considering new drugs, great care must be taken to avoid unforeseen problems. A good knowledge of the problem and a cautious approach combined with careful monitoring of the respiratory rate and adequacy of ventilation are the keys to the safe use of spinal and epidural opiates.

[A combination of sufentanil and 0.25% bupivacaine administered epidurally for obstetrical analgesia. Comparison with fentanyl and placebo]

The study reported was designed to determine whether 15 micrograms sufentanil would provide analgesia comparable in duration and quality with that given by 75 micrograms fentanyl, when associated with plain 0.25% bupivacaine for extradural analgesia for labour. Patients (n = 124) in labour and at full term were randomly divided into 3 groups. Group 1 (n = 41) were given 12 ml of 0.25% plain bupivacaine with saline, group 2 (n = 41) 12 ml of 0.25% plain bupivacaine with 75 micrograms fentanyl and group 3 (n = 42) 12 ml of 0.25% plain bupivacaine with 15 micrograms sufentanil. 11 cases were excluded from the study (8 Caesarean sections, 3 technical failures). The duration of analgesia obtained with the two opioids was similar (group 2: 126.7 +/- 6.5 min, p less than 0.01; group 3: 114.9 +/- 5.8 min, p less than 0.01; group 1: 93.6 +/- 5.4 min) as well as the quality of pain relief. There were no differences between the three groups with regard to Apgar scores. The only side-effect seen with sufentanil and fentanyl was pruritus (group 2: 21.9%, p less than 0.05; group 3: 21.4%, p less than 0.05; group 1: 2.4%). These results showed that 15 micrograms sufentanil could replace 75 micrograms fentanyl for extradural pain relief of labour with plain 0.25% bupivacaine. However, the use of opioids with local anaesthetics would seem to be of interest only if labour is likely to be prolonged.

Continuous epidural infusion of 0.075% bupivacaine for pain relief in labour. A comparison with intermittent top-ups of 0.5% bupivacaine

Seventy-three women who requested epidural analgesia during labour were randomly allocated in a prospective study to receive either a continuous epidural infusion of 0.075% bupivacaine at a rate of 12-18 ml/hour (38 mothers) or intermittent top-ups of 0.5% bupivacaine (35 mothers). Both groups received an initial dose of 6-8 ml bupivacaine 0.5%. Patients were asked to score their pain using a 10-cm linear scale prior to insertion of the epidural, 30 minutes after its insertion and hourly thereafter. The quality of analgesia in the continuous infusion group was significantly better than in the intermittent top-up group (p less than 0.025). There was no significant difference in the total dose of bupivacaine given to the two groups.

The relationship between the pharmacokinetics and pharmacodynamics of spinal opioids. Minireview based on a doctoral thesis

Spinal opioids have been used clinically since the late seventies to treat acute, traumatic, obstetric and chronic pain. In this article the influence of the pharmacokinetics on the dynamics of intrathecal and epidural opioid administration are discussed with reference to current knowledge.

Intrathecal administration of morphine for the relief of pains in labour and estimation of maternal and fetal plasma concentration of morphine

Thirteen healthy women in active labour received an intrathecal injection of morphine 1.0 mg. Eighty-five percent (11 patients) experienced acceptable or good pain relief. Analgesia set in 15-45 min after injection and reached a maximum after 15-120 min and lasted until delivery. Eighty-five percent (11 patients) of the patients developed mild side-effects i.e., pruritus, nausea and emesis. The intrathecal injection of morphine did not adversely affect the condition of the infant. Venous blood samples from the patients and umbilical cords for estimation of plasma morphine showed extremely low concentrations. No patients experienced any discomfort during the injection of morphine. These results indicate that morphine 1.0 mg administered intrathecally decreases labour pains to an acceptable level.

[Epidural anesthesia during labor: comparison of 3 combinations of fentanyl-bupivacaine and bupivacaine alone]

The association of bupivacaine and fentanyl appeared as the best method of inducing satisfactory obstetrical analgesia. But the various techniques of drug administration had to be detailed; this justified the present work, a single-blind controlled trial performed on 159 primipara women at term (except one of them), randomized in four groups, after informed consent. In each group, the number of patients, the age and the degree of uterine dilatation at the beginning of the epidural anaesthesia were comparable. Epidural anaesthesia aimed to improve the maternal comfort during labour. After a first epidural injection of 10 ml, several other injections of 6 ml were carried out according to four different protocols (I, II, III, IV), with different concentrations of fentanyl (respectively 0, 0.05, 0.1 and 0.15 mg). The mean total dosages of fentanyl were statistically higher in the protocols III and IV. The foetal cardiac rhythm and uterine contractions were monitored continuously as well as maternal blood pressure and heart beats during labour. The following parameters were assessed: contraction pain intensity (five point scale), the onset of analgesia, the duration of analgesia, the length of labour, the interval between the first drug injection and subsequent injections, the type of delivery. In the newborn, Apgar score was assessed at 1, 5 and 10 min after delivery. The degree of analgesia was statistically improved in the groups receiving fentanyl, without any differences between them. On the other hand, the length of labour was shorter with protocol II (lowest concentration of fentanyl).(ABSTRACT TRUNCATED AT 250 WORDS)

Labor pain assessment: validity of a behavioral index

There is a need for adequate and convenient measures for assessing obstetric pain. The present investigation was designed to develop a non-verbal objective measurement of labor pain based on the continuous observation of behavior. Validity and sensitivity of the instrument designed to assess pain throughout labor using standardized observational ratings were tested on a sample of 100 primiparae who were asked periodically to rate pain on a 5-point numerical scale. The use of a behavioral method of observation associated with a self-rating procedure comprises various advantages, especially because they may appreciate different factors of the pain experience. Behavioral and self-rating indices were satisfactorily correlated. The behavioral index correlates with the pre-partum anxiety score but the self-rating index does not. The positive results obtained in this preliminary study lead us to consider this behavioral index as a valid instrument.

Intrathecal morphine for pelvic and sacral pain caused by cancer

Ten patients underwent placement of a lumbar subarachnoid catheter attached to a subcutaneous reservoir allowing daily injection of intrathecal morphine sulfate by family members. Sacral and pelvic pain were fairly well controlled. Neck and leg pain and pain mediated by the celiac plexus were not as well controlled by the intrathecal injection of morphine. The only significant complication was collection of cerebrospinal fluid around three reservoirs. Using this technique, narcotic concentration and frequency of administration can be easily altered to provide a safe but effective dose. Lumbar administration appears to block pain from lumbar and sacral dermatomes without the sedating and mood-altering effects of systemic narcotics.

Pharmacokinetic aspects of spinal morphine analgesia

Epidural (E.D.) and intrathecal (I.T.) morphine (M) analgesia were studied in patients with pain after thoracotomy. The role of the pharmacokinetic properties of M. for the associated analgesia was also evaluated. M. concentrations in CSF and plasma were assayed using gas chromatography with EC detection. Analgesia was evaluated as the time postoperative until the patients again required analgetics and were given meperidine intramuscularly (I.M.) for thoracic pain. A lumbar site of E.D. and I.T. injection of M. resulted in a variable but in general longlasting postoperative analgesia although delayed after I.T. administration. The mean duration of analgesia after E.D. administration was dose-related (8.6 +/- 2.0 h, 13.0 +/- 3.5 h, and 15.6 +/- 2.6 h; means +/- SEM for the 2, 4 and 6 mg groups, respectively), which was comparable to that achieved after I.T. administration of 0.25 to 0.50 mg M. M. concentrations in plasma after E.D. administration were comparable in variability and magnitude to those found after I.M. administration. The concentrations of M. in plasma were not related to the long duration of analgesia and may only contribute to analgesia shortly after the E.D. administration. The reported time course of analgesia after E.D. injection with a delayed onset corresponded with the appearance of M. in the CSF. Fifteen min after E.D. administration, M. was found in higher concentrations in CSF than in plasma, but peak levels were not seen until 2 h after the injection. Both the high content of M. in CSF as expressed by AUC, as well as peak concentrations in CSF, were related to the longlasting analgesia after E.D. administration. A protracted clearance of M. from the CSF as a cause of longlasting analgesia was not found, M. was eliminated with a similar half-life from CSF and plasma. The high CSF concentrations of M. seen after E.D. administration were the result of a direct uptake across the dura. In contrast, the appearance of M. in CSF after I.M. administration of 10 mg was slower. Maximal concentration of M. in the CSF was reached after 3 h and the peak levels were on average about 100 times less than those found after E.D. injection of 6 mg morphine. CSF and plasma reached pseudoeliquilibrium at a ratio around 0.9 after I.M. administration. This is to be compared with a CSF/plasma concentration ratio around 100 after E.D. administration. A comparison of M. concentrations in the CSF after thoracic and lumbar E.D. injection showed that spinal CSF rapidly yielded comparable concentrations at the lumbar level.(ABSTRACT TRUNCATED AT 400 WORDS)

Epidural morphine after caesarean section

Morphine sulphate 5 mg and placebo administered epidurally after caesarean section under epidural analgesia were compared in a double-blind fashion. Morphine was significantly superior to placebo for pain relief, duration of pain relief, and reduction of parenteral narcotic requirements. Pruritus was the most commonly encountered side-effect. There was no statistical difference between morphine and placebo in the incidence of urinary catheterisation, vomiting, nausea, dizziness or drowsiness. No serious respiratory depression requiring treatment was observed.

[Epidural anesthesia using the bupivacaine-fentanyl combination for cesarean section]

This prospective study was designed to evaluate the benefit of a bupivacaine-fentanyl mixture vs bupivacaine alone in epidural anaesthesia for caesarean section. In 10 women, 0.5% bupivacaine (1.18 ml per metamer) was injected in the epidural space. In 20 women, 0.5% bupivacaine (1.06 ml per metamer) was injected by the same route together with fentanyl (1.70 +/- 0.09 micrograms X kg-1). The bupivacaine-fentanyl group showed a significantly shortened onset of analgesia (p less than 0.001), as well as a significant reinforcement of this analgesia graduated from 0 to 4 (p less than 0.01 at 25 min, p less than 0.001 at 75 min and at the maximum of pain, for the two sets of scores). All the Apgar scores were maximal at 5 min. No clinical respiratory depression was observed in either the mothers or the neonates. Fetal and maternal blood concentrations were in favour of respiratory innocuousness of the method (peak fentanyl concentrations: in mothers 1.5 ng X ml-1, in neonates 0.8 ng X ml-1). Fentanyl never induced any significant haemodynamic variations. Pruritus and nausea respectively occurred in six and two patients respectively in the bupivacaine-fentanyl group. In conclusion, in caesarean section, the adjunction of fentanyl to bupivacaine significantly improved analgesia without any clinical respiratory depression both in the mother and the neonate.

Epidural morphine by the caudal route for postoperative pain relief

In order to detect the ability of epidural morphine, administered by the caudal route, to produce pain relief and in order to compare pain relief by this method with intramuscular injections of opiates, 90 patients scheduled for surgery below the umbilical level were studied. Four milligrams of preservative-free morphine in 10 ml normal saline was compared with intramuscular injections of opiates, using a visual analogue scale. The average pain score was significantly lower in the epidural group during the first 12 postoperative hours. In the epidural group, 38% required additional intramuscular injections during the first 12 h, whereas 86% of the patients in the intramuscular group received opiate injections. No patients developed respiratory depression. Side effects were more common in the intramuscular group than in the epidural group. It is concluded that epidural morphine by the caudal route is a better choice than intramuscular injections in controlling postoperative pain below the umbilical level.

The maternal and fetal cardiovascular effects of epidural morphine in the sheep model

Interest in the use of epidural narcotics for analgesia has been widespread since the demonstration of opiate receptors in the spinal cord in the mid nineteen-seventies. Recently, several studies have attempted to evaluate the effectiveness of epidural narcotics for the relief of pain in labor and after cesarean section. Using the chronically catheterized maternal-fetal sheep model, we injected 5 mg of preservative-free morphine into the epidural space. No statistically significant changes were observed, neither in maternal or fetal arterial pressure and acid-base status, nor in maternal central venous pressure, systemic and pulmonary vascular resistance, cardiac output, or intrauterine pressure (p greater than 0.05). There was a significant, although small, decrease in maternal heart rate (8%) and uterine blood flow (9%) at 120 minutes (p less than 0.05), and then a return to control values. The maternal levels of morphine peaked at 15 minutes (29 ng/ml) and the fetal levels of morphine peaked at 90 minutes (3 to 4 ng/ml). We conclude that the injection of 5 mg of morphine into the maternal epidural space has no adverse effect on mother or fetus in the sheep model.

A study of pethidine kinetics and analgesia in women in labour following intravenous, intramuscular and epidural administration

1 Epidural administration of opiates for analgesia has recently generated widespread interest and would theoretically be advantageous as a method for relief of pain in labour. 2 Plasma pethidine concentrations were measured after intravenous, intramuscular and epidural administration of pethidine to women in labour and after epidural administration to non-pregnant female surgical patients. 3 Kinetic parameters were derived from the plasma concentration data in each group of subjects and the relationship between plasma kinetics and analgesia in labour were examined. 4 Absorption of pethidine from the epidural space in pregnant women in rapid and excepting the lower initial values, the average plasma concentration and area under the plasma concentration v time curve did not differ significantly (P less than 0.01) from those obtained with intravenous dosage, but were significantly higher (P less than 0.01) during the first 2 h after dosage than the results after intramuscular administration. The analgesia provided by the epidural route of administration was greater than with intravenous or intramuscular administration. 5 It is postulated that the analgesic efficacy of epidural pethidine in women in labour is due to a combination of systemic and local effects and that the local effect is attributable to the local anaesthetic properties of pethidine rather than a selective anti-nociceptive action on the spinal cord.

Extradural diamorphine in the control of pain following lumbar laminectomy

Catheters were inserted into the extradural space under direct vision at the time of surgery for prolapsed intervertebral disc or lumbar canal stenosis. In the post-operative period, diamorphine (3 mg in 5 ml water) was injected through the catheter when patients requested analgesia. In only four of 49 patients was significant pain relief not achieved after extradural diamorphine injection. In four other patients it was not possible to use this method of analgesia throughout the two post-operative days as planned. As judged by the improved mobility and by grading on a linear analogue pain scale, the quality of analgesia achieved was better than after intramuscular papaveretum (10-20 mg) and extradural diamorphine was requested less frequently. There were no serious side-effects in the patients studied, although the technique was not used in patients over 55 years of age. Extradural diamorphine appeared to be less effective in two patients who had undergone re-explorations.

Postoperative analgesia using epidural methadone. Administration by the lumbar route for thoracic pain relief

The effectiveness of methadone given postoperatively by the lumbar epidural route to patients following upper abdominal or thoracic surgery was assessed. Intermittent injections of methadone diluted in large volumes of normal saline were given during the first 48 hours after surgery. Pain relief was assessed by both the patient and an observer using a visual linear analogue scoring system. Methadone 4-5 mg in 18-20 ml normal provided good postoperative pain relief for 6-8 hours.

Epidural morphine and post-operative pain relief

Epidural morphine was compared with placebo in two randomly selected but similar groups of patients undergoing upper abdominal operations. There was no quantitative or qualitative difference in the analgesia obtained in the two groups of patients but there were significantly diminished long term requirements of intramuscular morphine in those who had been previously given epidural morphine when compared with epidural placebo. The possible causes and implications of this difference are discussed.

Comparison of epidural and intramuscular pethidine for analgesia in labour

Analgesia mediated by a direct spinal action of narcotic drugs administered via the epidural route may have considerable advantages over conventional(conduction block) epidural analgesia in labour. The efficacy, mode of action and placental transfer of epidurally administered narcotics in labour has not yet been established. We have compared the systemic absorption, analgesia and other effects on the mothers and transfer of drug to the fetus in primigravidae who received epidural or intramuscular pethidine 100 mg in labour. The superior analgesia following epidural pethidine did not appear to be attributable to a selective spinal action but rather to higher plasma concentrations of pethidine together with a possible weak regional conduction block due to local anaesthetic action of 1% pethidine solution. Epidural pethidine is not an advantageous method for providing analgesia in labour.

Pain relief in labour using epidural pethidine with adrenaline

The degree of pain was assessed by use of a visual analogue scale in 20 patients in established labour before and after the epidural injection of pethidine 50 mg with adrenaline 1:200,000. Forty-two doses were administered and of these 83% gave good pain relief and only 5% had no effect at all. The duration of action was longest following the first dose decreasing with subsequent doses. No evidence of sympathetic or motor blockade was found and side-effects were minimal. In the postpartum period 17 of the mothers expressed full satisfaction with the technique.

Clinical experience with epidural morphine

Epidural analgesia with morphine sulphate was administered to 130 patients. Of 96 patients with postoperative pain, 74 experienced good analgesia, 14 obtained a fair degree of pain relief, and in eight the method was unsatisfactory. Of the 34 non-operated patients 30 had good pain relief and the method failed in one. The most common cause of failure of analgesia was an incorrectly placed epidural catheter. Urinary difficulties and pruritus were encountered as the principal side-effects. One patient suffered depression of the level of consciousness following epidural drug administration and in one, epidural opiate appears to have contributed to hypotension.

Postoperative pain control with intrathecal morphine

A clinical study of the use of intrathecal morphine in two groups of surgical patients, 32 in all, showed that the morphine provided very powerful and prolonged analgesia with little disturbance of cerebral function. When combined with a spinal block it did not interfere with the action of the spinal anaesthetic. When combined with a relaxant technique of anaesthesia some persistent curarisation was seen. The only complication to emerge from the study was respiratory depression which could be very delayed in its offset. The depression was sufficient to induce carbon dioxide narcosis in two patients. It is suggested that the dose of intrathecal morphine in the very elderly should be very severely restricted as they appeared to be unduly sensitive to the respiratory depressant effect of morphine when given intrathecally.

Epidural morphine in terminal care

Case histories of three patients with intractable pain, all of whom responded to epidural morphine, are presented. Drug tolerance appeared to develop in two patients who survived longer than 10 days. Nevertheless this method of pain relief may be a useful adjunct to terminal care and in certain circumstances may allow for easier management in the patient's own home.

Maternal and fetal concentrations of morphine after epidural administration during labor

In this study of 20 healthy women in labor we attempted to determine the efficacy of epidural morphine as an obstetric analgesic. Four patients experienced some relief of pain while 16 patients reported no effect on pain. One newborn infant demonstrated possible morphine-induced respiratory depression. It was concluded that morphine is ineffective as an obstetric analgesic.

Continuous epidural infusion of fentanyl for postoperative analgesia

A continuous epidural infusion of fentanyl was used for control of postoperative pain in a series of 30 patients who had received an epidural anaesthetic for general surgical procedures. Fentanyl was originally administered at a maximal rate of 50 micrograms/hr but later reduced to 25 micrograms/hour or less. Satisfactory analgesia was provided in 24 patients, who required no other form of analgesia whatsoever. Three patients derived significant analgesia from the infusion, but did require occasional small supplementary doses of opiates. Three patients derived little or no benefit from the procedure. The only noticeable side effect was nausea and vomiting, which was less of a feature with the weaker solution. The method was used on general surgical wards with no extra demands being made on nursing staff. Many nursing procedures and physiotherapy could be carried out more conveniently than usual in the postoperative period.

Intrathecal morphine as sole analgesic during labour

In 12 consecutive unselected patients admitted to a consultant maternity unit one single injection of subarachnoid morphine sulphate 1.5 mg abolished pain during the first stage of labour. Pain in the second stage was abolished in four patients and lessened in three. During the early puerperium, pain at the site of the episitotomy was much reduced. Side effects included itching of the face, nausea and vomiting, and frontal headache, but these were mild and simply treated. They were even less severe in the last four patients, in whom barbotage was not used in administering the morphine. The high rate of forceps delivery and caesarean section (three cases of each) was not thought to be associated with the use of intrathecal morphine. These findings show that intrathecal morphine can abolish the pain of labour, whether spontaneous or induced, while preserving the mother's full awareness of labour and her co-operation in the second and third stages of labour. Further, controlled, trials are warranted.