Respiratory depression and spinal opioids

Intrathecal Morphine and Post-Operative Pain Relief in Robotic Surgeries: A Systematic Review and Meta-Analysis

Despite the potential benefits of intrathecal morphine (ITM), the precise role and dosing of ITM in robotic assisted surgery (RAS) remains unclear. This systematic review explores real-world evidence to evaluate the efficacy and outcomes of ITM in patients undergoing RAS. In accordance with PRISMA guidelines, a comprehensive search was conducted on four databases: MEDLINE, Embase, Cochrane Library and APA PsycInfo. Primary outcomes included pain scores at rest and on exertion at 24- and 48-h time intervals, and secondary outcomes aimed to explore the side effects of ITM. A meta-analysis was conducted to determine mean differences. A risk of bias assessment was conducted via the Cochrane Risk of Bias 2 tool. A total of 9 RCTs involving 619 patients were included in this review, of which 298 patients were administered ITM. Significant pain score reductions were observed both at rest (MD = -27.15; 95% CI [-43.97, -10.33]; I2 = 95%; p = 0.002) and on exertion (MD = -25.88; 95% CI [-37.03, -14.72]; I2 = 79%; p = 0.0003) 24 h postoperatively in the ITM groups, accompanied by a notable decrease in postoperative IV morphine equivalent consumption at 24 h (MD = -20.13; 95% CI [-30.74, -9.52]; I2 = 77%; p = 0.0002). ITM improved pain scores both at rest and on exertion at 24 and 48 h intervals, concurrently reducing the need for postoperative opioid consumption, but at the cost of an increased incidence of adverse events.

InTrathecal mORphine, traNsversus Abdominis Plane Block, and tramaDOl Infusion for Catheter-Related Bladder Discomfort in Patients Undergoing Robot-Assisted Laparoscopic Prostatectomy (TORNADO): A Pilot Prospective Controlled Study

Catheter-related bladder discomfort (CRBD), affecting surgical patients requiring large catheters, is often intolerable. In this prospective controlled study, we compared the efficacy of three analgesic approaches in the management of CRBD. Here, 33 patients undergoing robot-assisted laparoscopic prostatectomy (RALP) were allocated to the following three groups: intrathecal morphine (IM), transversus abdominis plane block (TAP), and tramadol intravenous infusion (TI). The primary outcome was CRBD assessed at admission in the recovery room (RR) (T0), and 1 h (T1), 12 h (T2), and 24 h (T3) after surgery. The secondary outcomes included the following: Aldrete score; postoperative pain, measured with a numerical rate scale (NRS) at T0, T1, T2, and T3; postoperative opioid consumption; and flatus. The patients of the IM group showed significantly lower CRBD values over time compared to the patients of the TI group (p = 0.006). Similarly, NRS values decreased significantly over time in patients receiving IM compared to patients treated with TI (p < 0.0001). Postoperative nausea and vomiting did not differ among the three groups. Postoperative opioid consumption was significantly lower in the IM group compared to the other two groups. Most patients of the IM group (9 of 11) had flatus on the first postoperative day. In conclusion, IM may prevent CRBD and reduce pain perception and postoperative opioid consumption and expedite bowel function recovery.

The problem of postoperative respiratory depression

WHAT IS KNOWN AND OBJECTIVE

Postsurgical recovery is influenced by multiple pre-, intra- and perioperative pharmacotherapeutic interventions, including the administration of medications that can induce respiratory depression postoperatively. We present a succinct overview of the topic, including the nature and magnitude of the problem, contributing factors, current limited options, and potential novel therapeutic approach.

COMMENT

Pre-, intra- and perioperative medications are commonly administered for anxiety, anaesthesia, muscle relaxation and pain relief among other reasons. Several of the medications alone or in joint-action can be additive or synergistic producing respiratory depression. Given the large number of surgical procedures that are performed each year, even a small percentage of postoperative respiratory complications translates into a large number of affected patients.

WHAT IS NEW AND CONCLUSION

Due to the large number of surgeries performed each year, and the variety of medications used before, during, and after surgery, the occurrence of postoperative respiratory depression is surprisingly common. It is a significant medical problem and burden on hospital resources. There is a need for new strategies to prevent and treat the acute and collateral problems associated with postoperative respiratory depression.

Transversus abdominis plane block and intrathecal morphine use in cesarean section: a retrospective review

OBJECTIVES

Cesarean delivery is an extremely common surgical procedure practiced worldwide. It is an open abdominal surgery, and is associated with significant postoperative pain. One modality that helps alleviate this pain is the transversus abdominis plane (TAP) block. This analysis sought to evaluate postoperative pain when this block was used in conjunction with intrathecal morphine.

METHODS

A retrospective review was performed of 142 patients who underwent cesarean section at our institution. Of those, 43 patients had a TAP block performed. The primary outcome for this analysis was the time to first opioid administration following discharge from the operating room. Secondary outcomes included differences in postoperative pain scores, and overall opioid consumption.

RESULTS

The average time to first opioid use postoperatively decreased in the TAP group when compared with the No-TAP group, 23.3 versus 12.1, respectively (difference of 48.2% (95% CI 74.0% to 24.3%); p<0.001) and opioid consumption was significantly decreased within the first 24 hours following surgery from 4.55 intravenous morphine equivalents (IVME) to 2.67 IVME, respectively (difference of 107.1% (95% CI 145.1% to 69.2%); p=0.006). Visual analog pain scores were significantly decreased in the TAP group versus the No-TAP group up to 36 hours postoperatively.

CONCLUSIONS

TAP blocks performed in conjunction with intrathecal morphine may decrease opioid use in the first 24 hours and improve pain scores for at least 36 hours following cesarean section. Because of the favorable safety profile, TAP blocks may contribute meaningfully to multimodal anesthesia for cesarean sections.

Apnea 6 h after a cesarean section

Intrathecal narcotics have proven to be invaluable in providing pain relief following a cesarean section. They also aid in earlier mobilization. Unfortunately, they come at the risk of delayed apnea requiring close monitoring for a prolonged period of time. Physicians may sometimes underestimate the risk of these delayed complications. This especially a big concern in hospitals that cannot provide the necessary postoperative monitoring required for these women. I present a case where it took more than 6 h after injection of narcotics before the complication occurred.

Clinical Study to Determine the Efficacy of Clonidine as an Adjuvant to Intrathecal Bupivacaine in Patients Undergoing Cesarean Section

Introduction

Spinal anesthesia with bupivacaine is associated with hypotension and inadequate postoperative analgesia. The addition of clonidine as an adjuvant to intrathecal bupivacaine is beneficial in reducing the dose of the local anesthetic and also provides prolonged postoperative analgesia.

Methodology

One hundred and five American Society of Anesthesiologists physical status Classes 1 and 2 parturient women undergoing elective cesarean section were randomly divided into three groups. Patients in Group C (control) received 2 ml of 0.5% of heavy bupivacaine (10 mg) with 0.5 ml of 0.9% saline to a total volume of 2.5 ml, those in Group H (high dose of bupivacaine) received 2 ml of 0.5% of heavy bupivacaine (10 mg) with 1 μg/kg of clonidine and 0.9% saline to make a total volume of 2.5 ml, and those in Group L (low dose of bupivacaine) received 1.5 ml of 0.5% of heavy bupivacaine (7.5 mg) with 1 μg/kg clonidine and 0.9% saline to make a total volume of 2.5 ml. Patients were observed for onset and duration of sensory and motor block and for postoperative analgesia.

Results

Patients who received clonidine as adjuvant had effective prolonged postoperative analgesia (Group H - 480 ± 40 min, Group L - 480 ± 34 min) as compared to control group (180 ± 19 min).

Conclusion

The dose of intrathecal bupivacaine 0.5% was effectively reduced to 7.5 mg by adding 1 μg/kg of clonidine as adjuvant in patients undergoing elective cesarean section.

Flip-Flop Phenomenon in Epidural Sufentanil Pharmacokinetics: A Population Study in Children and Infants

The aims of this study were to develop a population pharmacokinetic model of sufentanil coadministered with 0.2% ropivacaine as an epidural infusion in infants and describe the sufentanil absorption profile from epidural space. Data from 2 previously published studies were merged for analysis-20 infants aged 3-36 months receiving sufentanil as an epidural infusion and 41 children 0-17 years old receiving sufentanil as a long-term intravenous infusion. A population nonlinear mixed-effects model was built in NONMEM. Sufentanil pharmacokinetics were described by a 2-compartment model with first-order absorption. The effect of body size on all volume and clearance parameters was included in the model according to allometric scaling with theoretical exponents. The maturation process of metabolic clearance was described by the Hill model. During the model-building process the population was divided into 2 fractions with different typical values of metabolic clearance (CL1 and CL2). The typical values of systemic clearance scaled to a 70-kg patient for the 2 subpopulations were CL1 = 52.6 L/h and CL2 = 158 L/h. The parameters of the Hill function were 54.9 weeks for the postmenstrual age of 50% clearance maturation and 0.802 for the Hill coefficient. The typical values of distribution clearance and volumes of the central and peripheral compartments for a patient with a weight of 70 kg were Q = 40.5 L/h, VC = 7.63 L, and VT = 473 L, respectively. The value of the absorption rate constant from the epidural space was 0.0459/h, which suggests flip-flop pharmacokinetics of sufentanil after epidural administration.

Thoracic Epidural Analgesia

Thoracic epidural analgesia (TEA) offers a unique oppor tunity for the anesthesiologist to enhance postopera tive recovery for the thoracic surgery patient. By deliver ing analgesics to a limited dermatomal distribution, TEA can provide profound segmental analgesia and also serves to modulate neural outflow to improve cardiac and pulmonary parameters. The notable side-effects of hypotension and respiratory depression can be mini mized by using synergistic combinations of local anes thetic and opioids, and by adopting a continuous infu sion strategy. With thoughtful patient selection, careful technique, and a proactive approach to the recognition of the known hemodynamic and respiratory effects of epidural drugs, TEA can be administered safely. The significant benefits of TEA include better pain relief, increased FEV1, earlier extubation, and, perhaps, de creased morbidity and mortality.

Management of Pain in the Critically Ill

Analgesia for critically ill patients can be provided most effectively by the use of modern techniques. Under standing of the anatomical pathways for nociceptive sig nal transmission allows the use of techniques that mod ulate or block nociceptive information at several levels (periphery, spinal cord, and systemic). A comprehen sive discussion of analgesic techniques at each level is presented. Formulation of a treatment plan is discussed. Several examples are presented to show the decision- making process for the use of modern analgesic tech niques in critically ill patients.

Is a single low dose of intrathecal morphine a useful adjunct to patient-controlled analgesia for postoperative pain control following lumbar spine surgery? A preliminary report

BACKGROUND

Several studies addressing intrathecal morphine (ITM) use following spine surgery have been published either involving the pediatric population, using mid- to high-dose ITM, or not in conjunction with morphine patient-controlled analgesia (PCA).

OBJECTIVES

To determine whether low-dose ITM is a useful adjunct to PCA for postoperative pain control following elective lumbar spine surgery in adults.

METHODS

Thirty-two patients were enrolled in a double-blinded randomized controlled trial, and received either ITM or intrathecal placebo. Postoperatively, all patients were given a PCA pump and observed for the first 24 h in a step-down unit. Measurements of: total PCA morphine consumed in the first 24 h; intensity of pain; pruritus; nausea at 4 h, 8 h and 24&nbsp;h; time to first ambulation; length of hospital stay; and occurrences of respiratory depression were recorded.

RESULTS

The total PCA use was significantly lower in the ITM group. There were lower average pain scores in the ITM group, which increased to that of the intrathecal placebo group over 24 h; however, this failed to attain statistical significance. There were no differences in nausea, pruritus, time to first ambulation or hospital length stay. There were no cases of respiratory depression in either group.

CONCLUSIONS

ITM may be a useful adjunct to PCA, but did not decrease time to ambulation or length of stay.

The volume effect of lidocaine on thoracic epidural anesthesia in conscious Beagle dogs

OBJECTIVE

To evaluate the volume effect of local anesthetic solution on thoracic epidural analgesia in dogs.

STUDY DESIGN

Prospective, experimental trial.

ANIMALS

Five healthy adult Beagle dogs weighing 9.7 ± 1.3 kg.

METHODS

A catheter was inserted into the seventh thoracic epidural space using a lumbosacral approach, and secured with suture under total intravenous (IV) anesthesia with propofol. Each dog was administered four volume treatments (0.05, 0.10, 0.15 and 0.20 mL kg(-1)) of 2% lidocaine via the catheter at 12 hour intervals. In every treatment, dogs were re-anesthetized with propofol (6 mg kg(-1), IV) and isoflurane, and received iohexol at each volume to visualize the epidural distribution (ED) through computed tomography. Three hours after epidurography, when dogs had recovered from anesthesia, the appropriate volume of lidocaine was injected through the catheter, and sensory blockade (SB) in dermatomes was evaluated by pinching with a mosquito forceps. Results were presented as median (range), and the volume effect on ED and SB was analyzed with one-way Kruskal-Wallis anova.

RESULTS

In proportion to volumes (0.05, 0.10, 0.15 and 0.20 mL kg(-1)), there were significant increases in the extent of ED from 7.4 (5.5-9.0) to 10.4 (8.0-12.0), 13.2 (12.5-13.0), and 15.2 (13.0-18.0) vertebrae, respectively, p < 0.001, and in SB from 2.7 (1.0-5.0) to 6.8 (4.5-10.5), 9.9 (6.5-13.0), and 13.1 (11.0-15.0) dermatomes, respectively, p < 0.001. Unilateral ED and SB were observed in all treatments with various grades, and this distribution was more frequent in the low volume treatments. In the high volume treatments, temporary complications including Horner's syndrome, ataxia, paraplegia, depression, stupor, and intermittent cough occurred often.

CONCLUSIONS AND CLINICAL RELEVANCE

The increase in volume of local anesthetic solution improved SB by resulting in more consistent bilateral dermatome blockade as well as an extended blockade. However, caution should be exerted, as higher volume injections of lidocaine caused side effects in all dogs.

Possible delayed respiratory depression following intrathecal injection of morphine and bupivacaine in an alpaca

OBJECTIVE

To describe general anesthesia and successful treatment of an alpaca, which developed respiratory arrest 2 hours after intrathecal injection of morphine and bupivacaine.

CASE SUMMARY

A 10-day-old female alpaca weighing 7.3 kg was presented to our hospital with a fractured right tibia. The cria was anesthetized to repair the fracture with a dynamic compression plate. Anesthesia was induced with IV propofol and maintained with sevoflurane in 100% oxygen. Prior to the start of surgery the alpaca received an unintended intrathecal injection of 0.6 mL of a solution of 0.5 mg morphine (0.068 mg/kg) and 1.5 mg bupivacaine (0.2 mg/kg), after an attempted lumbo-sacral epidural. The alpaca developed respiratory arrest 120 minutes after the intrathecal injection was administered. Adequate hemoglobin-oxygen saturation was maintained despite minimal intermittent manual ventilation, but marked hypercapnia developed (PaCO2 of 17.3 KPa [130 mm Hg]). Delayed respiratory depression resulting from cephalad migration of intrathecal morphine was suspected. Ventilation was supported until the end of surgery when sevoflurane was discontinued. The trachea remained intubated, 100% oxygen was supplied, and ventilation was supported at 2-4 breaths/min for the next 60 minutes, but no attempts to breathe spontaneously were detected. Intravenous naloxone (0.3 mg [0.04 mg/kg]) was administered slowly to effect until adequate spontaneous ventilation and full consciousness returned. The anesthetic recovery of the alpaca was rapid and uneventful after the opioid antagonist was given.

NEW INFORMATION PROVIDED

Delayed respiratory depression is a potential complication after intrathecal administration of morphine. Careful dose-adjustment may reduce the risk, and close monitoring will result in early detection and treatment of this complication.

Bupivacaine-sufentanil versus bupivacaine-fentanyl in spinal anesthesia of patients undergoing lower extremity surgery

BACKGROUND

The addition of intrathecal opioids to local anesthetics seems to improve the quality of analgesia and prolong the duration of analgesia, when using a subarachnoid block in Iranian patients with their specific pain tolerance.

OBJECTIVES

The aim of this study was to evaluate the effects of adding fentanyl or sufentanil, to intrathecal bupivacaine, in terms of the onset and duration of; sensory block, motor block, hemodynamic effects and postoperative pain relief.

PATIENTS AND METHODS

This randomized clinical trial included 90 patients who underwent orthopedic lower limb surgeries. Subjects were divided into experimental groups; intrathecal fentanyl 25 µg (F), and sufentanil 2.5 µg (S), along with a placebo 0.5 mL normal saline (C) group, which were added to bupivacaine 0.5%, 15 mg. Duration of complete and effective analgesia was recorded (by a visual analogue scale-VAS). The pain scores were assessed postoperatively. Intraoperative mean arterial pressure (MAP), heart rate and oxygen saturation (SPO(2)) were recorded. The incidence of side effects such as; nausea, vomiting, pruritus, shivering, bradycardia and hypotension were also recorded.

RESULTS

MAP and heart rate results showed no significant changes at the designated time points among the three groups (P > 0.05). However, SPO2 and VAS showed significant changes at the designated time points among the three groups (P < 0.05). The duration of complete and effective analgesia was also significantly longer in the sufentanil group (P < 0.05). Motor block did not exhibit any significant difference (P = 0.67). Only pruritus as a side effect was significantly higher in the sufentanil group (P < 0.05), while all other evaluated side effects were significantly lower in the sufentanil group (P < 0.05).

CONCLUSIONS

The addition of 2.5-3 mcg sufentanil to 15 mg 0.05% bupivacaine maintained the patient's hemodynamic stability similar to fentanyl. Intrathecal sufentanil added to bupivacaine,when compared with fentanyl, may lead to prolonged duration of analgesia, facilitate the spread of the sensory block, increase mean SPO2 levels, and reduce overall side effects.

The effect of gabapentin versus intrathecal fentanyl on postoperative pain and morphine consumption in cesarean delivery: a prospective, randomized, double-blind study

PURPOSE

Pain after cesarean delivery is a leading cause of chronic pain and there are many attempts to reduce it without total success. Gabapentin is effective in reducing acute and chronic pain with little experience in parturient. The purpose of this study is to compare the effect of pre-emptive gabapentin with intrathecal fentanyl on reducing postoperative pain and morphine consumption in cesarean surgery.

METHODS

Seventy-eight primiparous women who scheduled for non-emergency cesarean delivery were enrolled in the study and separated into two groups. The control group received 12.5 mg of heavy bupivacaine 0.5 % plus 10 μg of fentanyl intrathecally and the case group received 300 mg of gabapentin orally 2 h before surgery and 12.5 mg of heavy bupivacaine 0.5 % intrathecally. Data collection including blood pressure, heart rate, neonate sedation, Apgar score, visual analogous scale at several hours, at first, need to analgesic postoperatively.

RESULTS

In the fentanyl group, the need for analgesic drug was earlier, total dose of morphine in 24 h and patient satisfaction was higher than the gabapentin group. The mean visual analogous scale at several hours postoperatively in the fentanyl groups was significantly higher than the gabapentin groups (P = 0.001).

CONCLUSION

Preemptive use of gabapentin is a safe and effective way to reduce postoperative pain and morphine consumption in parturients after cesarean surgery.

The effect of addition of intrathecal clonidine to hyperbaric bupivacaine on postoperative pain after lower segment caesarean section: A randomized control trial

Background:

Intrathecal clonidine prolongs spinal anesthesia but the optimum dose to be used in cesarean delivery is not yet known. We evaluated the effect of addition of intrathecal clonidine to hyperbaric bupivacaine on postoperative pain after lower segment caesarean section.

Methods:

A total of 105 parturients carrying a singleton fetus at term, scheduled to undergo elective LSCS under spinal anesthesia were randomized in a double blind fashion to one of the three groups. Group BF (n=35) received 2 ml of 0.5% hyperbaric bupivacaine+25 μg fentanyl, Group BC₅₀ (n=35) received 2 ml of 0.5% hyperbaric bupivacaine+50 μg clonidine, Group BC₇₅ (n=35) received 2 ml of 0.5% hyperbaric bupivacaine+75 μg clonidine.

Results:

The duration of postoperative analgesia was 184.73±68.64 min in group BF, 360.71±86.51 min in group BC₅₀ and 760.50±284.03 min in group BC₇₅, P<0.001. The incidence of hypotension was comparable, P=0.932, whereas the incidence of nausea and pruritis was significantly lower in groups BC₅₀ and BC₇₅ as compared to group BF, P<0.001. No other side effects of intrathecal clonidine were detected. Neonatal outcome was similar in all the three groups.

Conclusions:

Addition of 75 μg clonidine to hyperbaric bupivacaine in spinal anesthesia for LSCS significantly prolongs the duration of postoperative analgesia without any increase in maternal side effects. There was no difference in neonatal outcome.

A clinical approach to neuraxial morphine for the treatment of postoperative pain

Opioids are considered a “gold standard” in clinical practice for the treatment of postoperative pain. The spinal administration of an opioid drug does not guarantee selective action and segmental analgesia in the spine. Evidence from experimental studies in animals indicates that bioavailability in the spinal cord biophase is negatively correlated with liposolubility, and is higher for hydrophilic opioids, such as morphine, than lipophilic opioids, such as fentanyl, sufentanil and alfentanil. Epidural morphine sulphate has proven analgesic efficacy and superiority over systemically administered morphine for improving postoperative pain. However, pain relief after a single epidural injection of morphine could last less than 24 hours. Techniques used to administered and prolong opioid epidural analgesia, can be costly and inconvenient. Moreover, complications can arise from indwelling epidural catheterization, particularly in patients receiving anticoagulants. Clinical trials have shown that epidural morphine in the form of extended-release liposome injections (EREM) gives good analgesia for a period of 48 hours, with no need for epidural catheterisation. Intrathecal morphine produces intense analgesia for up to 24 hours with a single shot, and clinical recommendation is to choose the minimum effective dose and do not exceed 300 μg to prevent the delay respiratory depression.

[Postoperative analgesia: comparing continuous epidural catheter infusion of local anesthetic and opioid and continuous wound catheter infusion of local anesthetic]

BACKGROUND AND OBJECTIVES

Continuous wound infusion has been investigated as a method of postoperative pain control and its efficacy has been demonstrated when compared to saline infusion. The objective of this study was to compare the quality of postoperative analgesia, the use of opioids as rescue analgesia, patient satisfaction, and the incidence of complications between epidural catheter infusion of local anesthetic and opioids and continuous wound infusion of local anesthetic.

METHODS

Thirty-eight patients undergoing elective laparotomy under general anesthesia, randomly divided into two groups, participated in this study. Group I (GI) received postoperative patient-controlled epidural analgesia (PCEA) with continuous infusion of ropivacaine and fentanyl, while Group II (GII) receive postoperative patient-controlled continuous wound catheter infusion of ropivacaine. In the postoperative period, the following parameters were assessed: quality of analgesia through the Visual Analogue Scale; use of rescue opioids; and adverse effects driving patient satisfaction.

RESULTS

Decreased pain at rest and with movements (p < 0.05) and lower consumption of rescue opioids (p < 0.05) were observed in GI in all intervals evaluated, as well as greater patient satisfaction in the post anesthesia care unit (PACU). The incidence of complications was similar in both groups except for pruritus which prevailed in GI between 6 (p < 0.05) and 24 (p < 0.001) postoperative hours.

CONCLUSIONS

Postoperative analgesia with opioids and local anesthetics via PCEA was superior to the patient-controlled local anesthetic infusion into surgical wound. The incidence of side effects was similar in both groups.

Intrathecal tramadol added to bupivacaine as spinal anesthetic increases analgesic effect of the spinal blockade after major gynecological surgeries

The analgesic effect of the centrally acting opioid, tramadol, is well-known. It has been shown in clinical studies that using tramadol epidurally can provide longer duration of analgesia, without the common side effects of opioids. The study was undertaken to evaluate the duration of analgesia and/or pain free period produced by intrathecal tramadol added to bupivacaine in patients undergoing major gynecological surgery in a randomized double blind placebo controlled protocol. Fifty patients ASA I & II scheduled for Wardmayo's operation and Fothergill's operation were randomly allocated to two equal groups. Group A (n=25) received 3 ml of 0.5% hyperbaric bupivacaine (15 mg) with 0.2 ml of normal saline and Group B (n=25) received 3 ml 0.5% hyperbaric bupivacaine and 0.2 ml (20 mg) tramadol by intrathecal route at L3-4 inter space. Standard monitoring of the vital parameters was done during the study period. Levels of sensory block and sedation score were recorded every two minutes for the first 20 minutes, and then every ten minutes for the rest of the surgical procedure. Assessment of pain was done using Visual Analogue Scale (VAS). The study was concluded when the VAS was more than 40 mm, postoperatively. The patient was medicated and the time was recorded. Duration of analgesia or pain free period was estimated from the time of completion of spinal injection to administration of rescue analgesic or when the VAS score was greater than 40 mm. In Group B patients, the VAS score was significantly lower, as compared to Group A patients. The duration of analgesia was 210 ± 10.12 min in Group A; whereas, in Group B, it was 380 ± 11.82 min, which was found to be significant.

Headache attributed to non-vascular intracranial disorder

This chapter deals with non-vascular intracranial disorders resulting in headache. Headache attributed to high or low cerebrospinal fluid pressure is separated into headache attributed to idiopathic intracranial hypertension (IIH), headache attributed to intracranial hypertension secondary to metabolic, toxic, or hormonal causes, headache attributed to intracranial hypertension secondary to hydrocephalus, post-dural puncture headache, cerebrospinal fluid (CSF) fistula headache, headache attributed to spontaneous (or idiopathic) low CSF pressure. Headache attributed to non-infectious inflammatory disease can be caused by neurosarcoidosis, aseptic (non-infectious) meningitis or lymphocytic hypophysitis. Headache attributed to intracranial neoplasm can be caused by increased intracranial pressure or hydrocephalus caused by neoplasm or attributed directly to neoplasm or carcinomatous meningitis. Other causes of headache include hypothalamic or pituitary hyper- or hyposecretion and intrathecal injection. Headache attributed to epileptic seizure is separated into hemicrania epileptica and post-seizure headache. Finally headache attributed to Chiari malformation type I (CM1) and the syndrome of transient headache and neurological deficits with cerebrospinal fluid lymphocytosis (HaNDL) are described.

Inhibitory effect of fentanyl on phenylephrine-induced contraction of the rat aorta

PURPOSE

Fentanyl was reported to inhibit the alpha(1)-adrenoceptor agonist-induced contraction. The goal of this in vitro study was to identify the alpha(1)-adrenoceptor subtype primarily involved in the fentanyl-induced attenuation of phenylephrine-induced contraction in isolated endothelium-denuded rat aorta.

MATERIALS AND METHODS

Aortic rings were suspended in order to record isometric tension. Concentration-response curves for phenylephrine (10(-9) to 10(-5) M) were generated in the presence or absence of one of the following drugs: fentanyl (3 x 10(-7), 10(-6), 3 x10(-6) M), 5-methylurapidil (3 x10(-8), 10(-7), 3 x 10(-7) M), chloroethylclonidine (10(-5) M) and BMY 7378 (3 x 10(-9), 10(-8), 3 x 10(-8) M). Phenylephrine concentration-response curves were generated in the presence or absence of fentanyl in rings pretreated with either 3 x10(-9) M prazosin, 10(-9) M 5-methylurapidil or 3 x 10(-9) M BMY 7378.

RESULTS

Fentanyl (10(-6), 3 x 10(-6) M) attenuated phenylephrine-induced contraction in the rat aorta. 5-Methylurapidil and BMY 7378 produced a parallel rightward shift in the phenylephrine concentration-response curve. The pA(2) values for 5-methylurapidil and BMY 7378 were estimated to be 7.71 +/- 0.15 and 8.99 +/- 0.24, respectively. Fentanyl (10(-6) M) attenuated phenylephrine-induced contraction in rings pretreated with 10(-9) M 5-methylurapidil, but did not alter the rings when pretreated with 3 x 10(-9) M BMY 7378. Pretreatment of the rings with chloroethylclonidine showed a 72.9 +/- 2.3% reduction in phenylephrine-induced maximal contraction.

CONCLUSION

The results suggest that fentanyl attenuates phenylephrine-induced contraction by inhibiting the pathway involved in the alpha(1D)-adrenoceptor-mediated contraction of the rat aorta.

Combination of Ultra-Low Dose Bupivacaine and Fentanyl for Spinal Anaesthesia in Out-Patient Anorectal Surgery

This study investigated whether the addition of 25 μg fentanyl to an ultra-low (sub-anaesthetic) dose of intrathecal bupivacaine provides adequate anaesthesia for out-patient anorectal surgery, without increasing side-effects or delaying hospital discharge. Patients were randomly allocated to receive 2.5 mg 0.5% bupivacaine plus 25 μg fentanyl (group BF, n = 18) or 5 mg 0.5% bupivacaine alone (group B, n = 17). There were no significant differences in intra-operative outcomes, but mean recovery and discharge times were significantly shorter in group BF. There were no between-group differences in hypotension, bradycardia or respiratory depression and post-operative complications were comparable, apart from pruritus which was significantly more frequent in group BF. Fewer patients requested analgesic medication in the early post-operative period in group BF than in group B. In conclusion, 25 μg intrathecal fentanyl added to ultra-low dose (2.5 mg) bupivacaine provided good-quality spinal anaesthesia and reduced post-operative analgesic requirement in patients undergoing ambulatory anorectal surgery.

Respiratory depression after neuraxial opioids in the obstetric setting

Neuraxial opioids have contributed significantly to improved labor and postcesarean delivery analgesia. In the obstetric population, epidural and intrathecal opioids are associated with a very low risk of clinically significant respiratory depression. Although rare, respiratory depression is a serious risk; patients may die or suffer permanent brain damage as a consequence. This review discusses the mechanism and incidence, as well as the prevention, detection, and management of respiratory depression with morphine, extended-release epidural morphine, and lipophilic opioids in the labor and cesarean delivery setting.

Survey of intrathecal opioid usage in the UK

BACKGROUND AND OBJECTIVE

Intrathecal opioids are now used routinely in the UK for intra- and postoperative analgesia. The opioids of choice have altered over recent years and the dosage regimens used can vary between institutions. Concerns over safety have been reduced probably because much lower doses of opioids are now being used. This survey explored the practice of intrathecal opioid usage in the UK.

METHODS

We sent a questionnaire survey to 270 anaesthetic departments and received 199 replies, a response rate of 73.7%.

RESULTS

Intrathecal opioids were used in 175 (88.4%) departments. Of these departments, 107 (61.1%) had local guidelines or protocols in place. Opioids such as diamorphine (used in 136 (78.2%) of departments) and fentanyl (129 (74.1%)) with a shorter duration of action are now more commonly used than morphine (37 (21.3%)) for intrathecal analgesia. In 96 (54.5%) departments, patients were nursed on regular surgical wards following administration of spinal opioids.

CONCLUSIONS

The use of low-dose lipophilic intrathecal opioids for postoperative analgesia is widespread in the UK. Patients are commonly nursed in low-dependency post-anaesthetic care areas. The low incidence of adverse events reported by the respondents along with the popularity of the technique suggests that low-dose spinal opioid administration is safe.

Intrathecal sufentanil (1.5 microg) added to hyperbaric bupivacaine (0.5%) for elective cesarean section provides adequate analgesia without need for pruritus therapy

PURPOSE

We compared the effects of different doses of intrathecal sufentanil when administered together with hyperbaric bupivacaine for elective caesarean section.

METHODS

This was a prospective, randomized, double-blind, controlled trial involving 100 pregnant women, American Society of Anesthesiologists (ASA) I-II, who were scheduled for elective caesarean section under spinal anesthesia. The patients were assigned to four groups according to the dose of sufentanil used: no sufentanil (group I; placebo) or 1.5, 2.5, or 5.0 microg sufentanil (groups 2-4, respectively). In every group, the local anesthetic used was hyperbaric bupivacaine 0.5% (12.5 mg), and the total volume of the solution was 3.5 ml. The duration of complete analgesia, maternal side effects, and maternal/fetal outcomes were recorded. The duration of complete analgesia was defined as the time from intrathecal injection to a vernal analogue score (VAS) of more than 0.

RESULTS

No patient experienced intraoperative pain. The duration of complete analgesia was prolonged in all groups receiving opioids. The duration of the analgesia and the 0- to 6-h intravenous analgesic requirements were similar in the sufentanil groups. Moreover, the sufentanil groups had longer durations of complete analgesia than the placebo group. Pruritus was more frequent in the 2.5- and 5-microg sufentanil groups than in the 1.5-microg sufentanil and placebo groups. There were no differences among the groups in umbilical cord blood gases on in neonatal Apgar scores.

CONCLUSION

The addition of sufentanil 1.5 and 2.5 microg to hyperbaric bupivacaine provided adequate anesthesia for caesarean delivery and good postoperative analgesia. In addition, the incidence of pruritus was significantly lower in the 1.5-microg sufentanil group when compared with that in the 2.5- and 5-microg groups.

The role of intrathecal drugs in the treatment of acute pain

Intrathecal opioids are widely used as useful adjuncts in the treatment of acute and chronic pain, and a number of non-opioid drugs show promise as analgesic drugs with spinal selectivity. In this review we examine the historical development and current use of intrathecal opioids and other drugs that show promise for treating pain in the perioperative period. The pharmacology and clinical use of intrathecal morphine and other opioids is reviewed in detail, including dosing guidelines for specific surgical procedures and the incidence and treatment of side effects associated with these drugs. Available data on the use of non-opioid drugs that have been tested intrathecally for use as analgesics are also reviewed. Evidence-based guidelines for dosing of intrathecal drugs for specific surgical procedures and for the treatment of the most common side effects associated with these drugs are presented.

The effect of adding intrathecal magnesium sulphate to bupivacaine-fentanyl spinal anaesthesia

BACKGROUND

The addition of intrathecal (IT) magnesium to spinal fentanyl prolongs the duration of spinal analgesia for vaginal delivery. In this prospective, randomized, double-blind, controlled study, we investigated the effect of adding IT magnesium sulphate to bupivacaine-fentanyl spinal anaesthesia.

METHODS

One hundred and two ASA I or II adult patients undergoing lower extremity surgery were recruited. They were randomly allocated to receive 1.0 ml of preservative-free 0.9% sodium chloride (group S) or 50 mg of magnesium sulphate 5% (1.0 ml) (group M) following 10 mg of bupivacaine 0.5% plus 25 microg of fentanyl intrathecally. We recorded the following: onset and duration of sensory block, the highest level of sensory block, the time to reach the highest dermatomal level of sensory block and to complete motor block recovery and the duration of spinal anaesthesia.

RESULTS

Magnesium caused a delay in the onset of both sensory and motor blockade. The highest level of sensory block was significantly lower in group M than in group S at 5, 10 and 15 min (P < 0.001). The median time to reach the highest dermatomal level of sensory block was 17 min in group M and 13 min in group S (P < 0.05). The mean degree of motor block was also lower in group M at 5, 10 and 15 min (P < 0.001). The median duration of spinal anaesthesia was longer in group M (P < 0.001).

CONCLUSION

In patients undergoing lower extremity surgery, the addition of IT magnesium sulphate (50 mg) to spinal anaesthesia induced by bupivacaine and fentanyl significantly delayed the onset of both sensory and motor blockade, but also prolonged the period of anaesthesia without additional side-effects.

Comparison of Lumbar Epidural Tramadol and Lumbar Epidural Morphine for Pain Relief After Thoracotomy: A Repeated-Dose Study

OBJECTIVE

The purpose of this study was to compare lumbar epidural morphine and lumbar epidural tramadol with respect to onset and duration of analgesia, analgesic efficacy, and drug-related side effects after muscle-sparing thoracotomy.

DESIGN

Prospective, randomized, double-blind, clinical study.

SETTING

Single university hospital.

PARTICIPANTS

Forty patients who underwent elective muscle-sparing thoracotomy.

INTERVENTIONS

Before anesthesia induction, an epidural catheter was placed in the L2-3 or L3-4 interspace using the loss-of-resistance technique. On arrival at the intensive care unit, patients were randomized to receive doses of either 100 mg of tramadol (group T) or 4 mg of morphine (group M) via the lumbar epidural catheter. Each dose was diluted in 10 mL of normal saline. On awakening from anesthesia, if the patient's pain score on a 0- to 100-mm visual analog scale was above 40 mm, the initial epidural drug dose was administered. The initial injection in each case was taken as time 0. Subsequent pain scores above 40 mm were considered indications for epidural dosing; each patient was allowed 2 doses in the first 12 hours postoperatively and 2 more in the second 12 hours.

MEASUREMENTS AND MAIN RESULTS

The groups' analgesia onset times were similar, but duration of analgesia was significantly shorter in group T than in group M (p < 0.01). There were no differences between the groups with respect to pain scores at rest or during coughing at any of the time points investigated. Sedation scores were lower in group T than in group M at 1, 2, 3, 4, and 8 hours (p value range, 0.0001-0.05). Compared with group T, group M showed significantly greater drops in arterial oxygen tension from baseline at 3, 4, 8, and 12 hours (p value range, 0.0001-0.05). The group means for arterial carbon dioxide tension and respiratory rate were similar at all time points investigated.

CONCLUSION

The study revealed that the quality of analgesia achieved with repeated doses of lumbar epidural tramadol after muscle-sparing thoracotomy is comparable to that achieved with repeated doses of lumbar epidural morphine. Compared with morphine, lumbar epidural tramadol results in less sedation and a less-pronounced decrease in oxygenation.

Differential respiratory effects of [Dmt1]DALDA and morphine in mice

H-Dmt-D-Arg-Phe-Lys-NH(2) ([Dmt(1)]DALDA, dDAL), a highly selective mu-opioid peptide, produces potent analgesia without respiratory depression after intrathecal administration. Despite carrying 3+ net charge, dDAL is also a potent analgesic after systemic administration. We compared the respiratory effects of dDAL and morphine after subcutaneous administration in mice using whole body plethysmography. Analgesic doses of 3 and 10 times ED(50) were examined. Both drugs dose-dependently decreased respiratory frequency and minute volume in room air. Tidal volume was increased by the lower dose of morphine, while it was decreased by the higher dose of dDAL. The decrease in minute volume by dDAL and morphine was completely reversed by naloxone. No difference in ventilatory response to CO(2) was observed between dDAL and morphine at three times ED(50). Ventilatory response to hypoxia was significantly diminished by dDAL compared to morphine and saline, and this effect of dDAL was naloxone-irreversible. Thus dDAL likely reduces the sensitivity of the peripheral chemoreflex loop through a non-opioid action.

Epidural analgesia associated with a fatal outcome in a patient with an unrecognized brain tumour

A fatality associated with epidural analgesia in a patient with an unsuspected brain tumour has not been reported in the literature. We describe a case of postoperative lumbar epidural analgesia in a 54-year-old female patient who had an undiagnosed brain tumour and a fatal outcome postoperatively. The factors that potentially contributed to this mishap and the possible alternative management of this patient are discussed.

Spinalan�sthesie bei der Arthroskopie des Kniegelenks

BACKGROUND AND OBJECTIVE

Intrathecal morphine provides effective postoperative analgesia but is associated with the risk of respiratory depression. A dose of only 0.1 mg has been shown to be optimal for effective and safe pain relief after abdominal surgery. This study was designed to determine whether the addition of 0.1 mg of morphine to the local anesthetic for spinal anesthesia produces adequate analgesia following arthroscopic knee joint surgery.

METHODS

A prospective, randomized, placebo-controlled, double-blind clinical trial was performed. Forty ASA I/II patients undergoing knee arthroscopy under spinal anesthesia were randomized to receive either mepivacaine 4% with 0.1 mg of morphine or mepivacaine 4% with saline (placebo) intrathecally. Postoperative analgesia consisted of intravenous morphine delivered by patient-controlled analgesia (bolus: 2 mg, lockout time: 5 min). During the study period of 24 h, pain intensity at rest and on movement (visual analogue scale, 0: no pain, 100: maximum pain), vigilance, and vital parameters were recorded every hour.

RESULTS

There were no statistically significant differences between the two groups in postoperative pain scores, morphine requirements, vigilance, blood pressure, heart rate, and breathing frequency. The patients of the morphine group required 12.3+/-10.2 mg (mean+/-SD) and those of the placebo group 11.6+/-8.4 mg of intravenous morphine from patient-controlled analgesia. The pain scores at rest and on movement were 10.0+/-8.1 and 16.0+/-12.6 in the morphine group and 8.2+/-7.9 and 11.7+/-11.3 in the placebo group. We did not observe severe side effects in any of the patients.

CONCLUSION

Intrathecal administration of 0.1 mg of morphine does not contribute to postoperative analgesia after arthroscopic knee joint surgery.

Definitions of "respiratory depression" with intrathecal morphine postoperative analgesia: a review of the literature

PURPOSE

To review the postoperative intrathecal morphine (ITM) analgesia literature for their definitions of "respiratory depression" (RD).

SOURCE

Medline (1966 - June Week 5 2001) and reference lists were searched for original studies involving bolus-dose ITM for postoperative analgesia, which used "respiratory depression" or similar terms.

PRINCIPLE FINDINGS

The search identified 209 studies. These were included if ITM use was appropriate (bolus dose, postoperative analgesia) and the term "respiratory depression" was used, which left 96 studies remaining. Forty-four (46%) did not define "RD" despite using this term. A further 24 (25%) defined RD with respiratory rate (RR) alone. Only 28 (29%) defined RD with more than RR alone. There was no statistically significant association between the presence of a definition for RD with study design, study size or publication period. Also, no significant association existed between rigorousness of RD definitions and the above factors.

CONCLUSION

The term "respiratory depression" has no clear definition from a review of the literature on ITM use for postoperative analgesia. While defining RD with bradypnea is superior to having no definition, this is still inadequate. In future research, the consistent use of terms with specific meanings will facilitate understanding the true incidence of ITM's respiratory effects. If "respiratory depression" is used, then an explicit definition of its meaning should be provided. Future research must also address what is clinically significant respiratory impairment from intrathecal opioids, and how to optimally monitor for this. Further delineating their risks vs benefits will allow for more optimal dosing.

Perineal analgesic actions of epidural clonidine in cattle

OBJECTIVE

To determine the analgesic, sedative, motor, cardiac and respiratory effects of epidural clonidine in cattle.

STUDY DESIGN

Prospective randomized study.

ANIMAL POPULATION

Six healthy male cattle weighing between 236 and 365 kg.

METHODS

To investigate the effect of epidural clonidine, the animals received 2 and 3 μg kg^-1 of clonidine diluted to 8 mL with 0.9% saline. Two treatments were utilized as controls. The animals from the first control treatment received 2% lidocaine (0.4 mg kg^-1) and those from the second received an equal volume of 0.9% saline. Each animal received each treatment in random order. Evaluations of analgesia, sedation, muscle relaxation, heart rate, respiratory rate and rectal temperature were obtained at 0 (basal), 2, 5, 10, 15 and 30 minutes after epidural injection, and then at 30-minute intervals until loss of analgesia occurred. All the animals received a standard noxious stimulus consisting of needle insertion into the skin and deep muscle; a 4-point scale was used to score the response. A second scale was used to score sedation and a third for muscle relaxation.

RESULTS

Both doses of clonidine were effective in producing analgesia of the tail, perineum, and upper hindlimb. Complete analgesia was present before (mean ± SE = 9 ± 4 vs. 19 ± 9 minutes) and lasted longer (311 ± 33 vs. 192 ± 27 minutes) for the 3 μg kg^-1versus the 2 μg kg^-1 dose, respectively. A dose-dependent sedative effect of clonidine was also observed, with a peak effect between 60 and 180 minutes. No effects on heart or respiratory rates were observed with either dose of clonidine.

CONCLUSIONS

Epidural administration of 2 and 3 μg kg^-1 of clonidine in cattle in this study provided bilateral perineal analgesia/anesthesia with a dose-dependent onset and duration of action.

CLINICAL RELEVANCE

Further studies are required to determine whether the analgesia is sufficient for surgery.

Hypercarbic and hypoxic ventilatory responses after intrathecal administration of bupivacaine and sameridine

Sameridine is a new compound with both local anesthetic and opioid properties (partial micro -opioid receptor agonist). It was intended for intrathecal administration to provide anesthesia for surgery and extended postoperative analgesia. In this double-blinded pharmacodynamic study with a two-parallel-group design, we investigated, during a 24-h period, the effects of intrathecal sameridine and bupivacaine on ventilation at rest and at ventilatory challenges during hypercarbia and hypoxia. Twenty-four healthy volunteers received either 25 mg of sameridine or 15 mg of bupivacaine intrathecally. Ventilation was measured by pneumotachography and in-line capnography. Sedation was rated by a visual analog scale. Segmental spread and development of motor and sensory block were similar in both groups. There was a decrease in tidal volume 2.5 to 6 h after injection in the bupivacaine group. This was seen only at 4 h in the sameridine group. There were no other major ventilatory differences between sameridine and bupivacaine during resting ventilation. Hypercarbic (tidal volume, mean inspiratory flow) and hypoxic (mean inspiratory flow) ventilatory responses were slightly decreased in the sameridine group, but not in the bupivacaine group. We conclude that intrathecal administration of sameridine or bupivacaine in healthy volunteers produces similar, minor effects on ventilatory responses over a 24-h observation period.

Continuous epidural infusion of racemic methadone results in effective postoperative analgesia and low plasma concentrations

PURPOSE

To compare two protocols of epidural administration of racemic methadone for postoperative analgesia (continuous infusion and intermittent bolus), focussing on plasma concentration, analgesic efficacy and side effects.

METHODS

Ninety patients undergoing abdominal or lower-limb surgery were randomly assigned to two groups in a prospective double-blind design. The continuous infusion patients (n=60) received initial doses of 3 to 6 mg followed by 6 to 12 mg by continuous infusion over 24 hr. The bolus administration patients (n=30) received repeated boluses of 3 to 6 mg of racemic methadone every eight hours. Pain intensity was assessed on a visual analog scale. Amount of supplementary analgesia was recorded, as was the incidence of side effects. Plasma methadone concentrations were determined by high performance liquid chromatography. Treatment was continued for 72 hr.

RESULTS

Pain relief was good and comparable in both groups throughout the three days of treatment. No accumulation of plasma racemic methadone was observed in either group, although the concentrations were significantly higher in the bolus group. Miosis was significantly more frequent in the bolus group.

CONCLUSION

Plasma methadone concentrations were significantly lower with continuous infusion. Plasma methadone accumulation, which is considered the main disadvantage for its purported influence on the incidence of side effects, did not occur at the doses used over the three days of treatment that we report.

The use of bupivacaine and fentanyl for spinal anesthesia for urologic surgery

We evaluated the effect of 25 microg of fentanyl added to bupivacaine on sensory and motor block. By using a double-blinded study design, 80 men undergoing urologic surgery were randomized into the following four groups: Group I, bupivacaine 10 mg; Group II, bupivacaine 10 mg + fentanyl 25 microg; Group III, bupivacaine 7.5 mg + fentanyl 25 microg; Group IV, bupivacaine 5 mg + fentanyl 25 microg. The final volume of intrathecal injectate was adjusted to 2. 5 mL with sterile distilled water. Spinal anesthesia was administered with the 27-gauge Whitacre needle at the L2-3 interspace with the patient in the sitting position. Neural block was assessed by using pinprick and a modified Bromage scale. The degree of motor block was more profound in Group II compared with Group I at the end of operation. In Group IV, there was no motor block at the end of operation in any of the patients. The median level of the upper limit of the sensory block was higher than T(7) in all groups before the start of surgery. The addition of 25 microg of fentanyl to 5 mg of bupivacaine resulted in short-acting motor block. When 25 microg of fentanyl was added to 10 mg of bupivacaine, it increased the intensity and duration of motor block. Only 5 (6. 3%) of the patients needed supplemental analgesia during the operation. ¿abs¿

Effects of intrathecal morphine on the ventilatory response to hypoxia

BACKGROUND

Intrathecal administration of morphine produces intense analgesia, but it depresses respiration, an effect that can be life-threatening. Whether intrathecal morphine affects the ventilatory response to hypoxia, however, is not known.

METHODS

We randomly assigned 30 men to receive one of three study treatments in a double-blind fashion: intravenous morphine (0.14 mg per kilogram of body weight) with intrathecal placebo; intrathecal morphine (0.3 mg) with intravenous placebo; or intravenous and intrathecal placebo. The selected doses of intravenous and intrathecal morphine produce similar degrees of analgesia. The ventilatory response to hypercapnia, the subsequent response to acute hypoxia during hypercapnic breathing (targeted end-tidal partial pressures of expired oxygen and carbon dioxide, 45 mm Hg), and the plasma levels of morphine and morphine metabolites were measured at base line (before drug administration) and 1, 2, 4, 6, 8, 10, and 12 hours after drug administration.

RESULTS

At base line, the mean (+/-SD) values for the ventilatory response to hypoxia (calculated as the difference between the minute ventilation during the second full minute of hypoxia and the fifth minute of hypercapnic ventilation) were similar in the three groups: 38.3+/-23.2 liters per minute in the placebo group, 33.5+/-16.4 liters per minute in the intravenous-morphine group, and 30.2+/-11.6 liters per minute in the intrathecal-morphine group (P=0.61). The overall ventilatory response to hypoxia (the area under the curve) was significantly lower after either intravenous morphine (20.2+/-10.8 liters per minute) or intrathecal morphine (14.5+/-6.4 liters per minute) than after placebo (36.8+/-19.2 liters per minute) (P=O.003). Twelve hours after treatment, the ventilatory response to hypoxia in the intrathecal-morphine group (19.9+/-8.9 liters per minute), but not in the intravenous-morphine group (30+/-15.8 liters per minute), remained significantly depressed as compared with the response in the placebo group (40.9+/-19.0 liters per minute) (P= 0.02 for intrathecal morphine vs. placebo). Plasma concentrations of morphine and morphine metabolites either were not detectable after intrathecal morphine or were much lower after intrathecal morphine than after intravenous morphine.

CONCLUSIONS

Depression of the ventilatory response to hypoxia after the administration of intrathecal morphine is similar in magnitude to, but longer-lasting than, that after the administration of an equianalgesic dose of intravenous morphine.

Applications of intrathecal catheters in children

Access to the intrathecal space may be required for sampling of cerebrospinal fluid for diagnostic purposes, for the administration of pharmacological agents, or for cerebrospinal fluid (CSF) drainage to lower intracranial pressure. The current report details five children in whom a percutaneously placed lumbar intrathecal catheter was used: (i) to provide intraoperative surgical anaesthesia instead of general anaesthesia (ii); to deliver intrathecal fentanyl to provide postoperative analgesia (iii); to provide chronic pain control during the terminal stages of metastatic malignancy; (iv) to allow repeated doses of intrathecal chemotherapy; and (v) to allow CSF drainage and prevent CSF leakage following frontal encephalocele repair. The indications and applications of intrathecal catheters in the paediatric aged patient are reviewed.

Thoracic epidural anaesthesia and analgesia: United Kingdom practice

BACKGROUND

Thoracic epidural analgesia has become increasingly practised in recent years. Complications are rare but potentially serious and, consequently, careful evaluation is required before undertaking this technique. The practice surrounding this procedure varies widely amongst anaesthetists.

METHODS

A postal survey to examine the practice of thoracic epidural analgesia was sent to all Royal College of Anaesthetists tutors in the United Kingdom.

RESULTS

Responses were received from 240 tutors, representing a return rate of 83%. When obtaining consent for thoracic epidural cannulation, 42% of respondents mentioned risk of a dural tap complication and 11% mentioned neurological damage. Fifty percent of respondents performed epidural cannulation following induction of general anaesthesia. The practice of epidural insertion in patients with abnormal coagulation varied, although over 80% of respondents did not consider concurrent treatment with either aspirin or non-steroidal anti-inflammatory drugs a contraindication. Sterile precautions for epidural insertion also varied between anaesthetists. Postoperatively, 95% of respondents used an opioid-based bupivacaine solution for epidural infusions, and these were most commonly nursed on general surgical wards (63%). Seventy-eight percent of hospitals provided an acute pain team to review epidural analgesia.

CONCLUSION

In the United Kingdom, there is little consensus in the practice of thoracic epidural analgesia relating to the issues of informed consent, epidural cannulation in patients with deranged clotting and the sterile precautions taken prior to performing epidural insertion. Most respondents use an opioid-based bupivacaine solution to provide postoperative epidural analgesia. Most hospitals in the UK now provide an acute pain service for thoracic epidural follow-up.