Randomized, double-blind comparison of patient-controlled epidural infusion vs nurse-administered epidural infusion for postoperative analgesia in patients undergoing colonic resection

BACKGROUND: There is little published evidence of the analgesic efficacyof patient-controlled epidural analgesia (PCEA) for postoperativepain relief. The aim of this study was to compare the analgesicefficacy of epidural infusion of bupivacaine 0.125% and fentanyl4 µg ml^–1 administered by either PCEAwith a background infusion or nurse-administered continuousepidural infusion (CEI) after major intra-abdominal surgery. METHODS: In a double-blind, randomized clinical trial, 205 adult patientsundergoing colonic resection by laparotomy received either PCEAor CEI. Pain scores were recorded via a four-point verbal ratingscale at 1, 2, 3, 4, 8, 12, 24, 48, and 72 h after surgery.The administration of epidural top-ups and systemic analgesiaover the same period was also recorded, and patient satisfactionquestionnaires completed. RESULTS: The median area under the curve of pain against time was significantlylower in the PCEA group (2 vs 24, P<0.001) as were mediansummary pain scores on movement (0.67 vs 1.33, P<0.001).Significantly fewer patients in the PCEA group received oneor more epidural top-ups (13 vs 36%, P = 0.0002) or any systemicanalgesics (41 vs 63%, P = 0.0021). Patients in the PCEA groupwere significantly more likely to be very satisfied than inthe CEI group (76 vs 43%, P<0.0001). CONCLUSIONS: PCEA provides greater analgesic efficacy than CEI for postoperativeanalgesia after major intra-abdominal surgery, and a decreasedrequirement for physician or nurse intervention.     

Responsive Contingency Planning: a novel system for anticipated difficulty in airway management in dental abscess

BACKGROUND: This study is of a novel system for management of anticipated difficult airway (Responsive Contingency Planning). It is based on the notion that almost all problems in airway management have already been experienced, so they can be anticipated and prepared for using 'worst case' planning. METHODS: Anaesthetic colleagues were introduced to the new system. Thirty-two patients with dental abscess were recruited for anaesthetic airway management based around the new scheme. Data collection involved a preoperative assessment of problems specific to dental abscess, fascia-spaces involved, details of the contingency planning process, laryngoscopy grade, and comments regarding the efficacy of the new system. RESULTS: No problems were encountered that had not been anticipated during planning and colleagues' comments about using the system were generally favourable. Examples are highlighted to suggest how the planning may have avoided certain complications (e.g. abscess rupture) and helped in dealing with others when they occurred. If trismus (2 cm) after induction of anaesthesia. In contrast, difficult laryngoscopy (grade 3 or 4) occurred in 6/15 cases of floor of mouth infection. CONCLUSIONS: The system fulfilled expectations for its use at this stage of development. It can be easily updated for refinements, alternative techniques, and tailoring to any difficult airway scenario. Computerization should make it easier to use and flag-up inconsistencies. Floor of mouth infections in the presence of trismus are easily underestimated and require careful assessment.     

An isobolographic analysis of diamorphine and levobupivacaine for epidural analgesia in early labour

Background: Few data describe the pharmacological interactions between localanaesthetics and opioids. The aim of this study was to measurethe median effective concentration (MEC) of diamorphine andlevobupivacaine when given separately and as mixtures for epiduralanalgesia, and determine whether the combination is additiveor synergistic. Methods: One hundred and twenty patients were enrolled in this prospectiverandomized, two-phase, double-blind study. In the first phase,60 women were randomized to receive a fixed 20 ml volumeof either levobupivacaine or diamorphine epidurally . Dosingwas determined using up-down sequential allocation with testingintervals, respectively, of 0.01%w/v and 12.5 µg ml^–1.After estimations of the MEC of levobupivacaine and diamorphine,a further 60 patients were randomized in the second phase toone of the three mixtures: (a) diamorphine 70 µg ml^–1(fixed) and levobupivacaine (testing interval 0.004%w/v, startingat 0.044%w/v); (b) levobupivacaine 0.044%w/v (fixed) and diamorphine(testing interval 7 µg ml^–1, startingat 70 µg ml^–1); and (c) bivariate diamorphineand levobupivacaine (testing intervals of 7 µg ml^–1and 0.004%w/v starting at 70 µg ml^–1 and0.044% w/v respectively). Results: The MEC estimates from the first phase were 143.8 µg ml^–1(95% CI 122.2–165.3) for diamorphine and 0.083%w/v (95%CI 0.071–0.095) for levobupivacaine. In the second phase,the MEC and interaction index () of the three combinations were:diamorphine 65.5 µg ml^–1 (56.8–74.2), = 0.99; levobupivacaine 0.041%w/v (0.037–0.049), = 0.98;and for the fixed combination diamorphine 69.5 µg ml^–1(60.5–78.5) and levobupivacaine 0.044%w/v (0.039–0.049), = 1.02. Conclusion: The combination of diamorphine and levobupivacaine is additiveand not synergistic when used for epidural analgesia in thefirst stage of labour.     

Semi-invasive monitoring of cardiac output by a new device using arterial pressure waveform analysis: a comparison with intermittent pulmonary artery thermodilution in patients undergoing cardiac surgery

BACKGROUND: Thermodilution technique using a pulmonary artery catheter (PAC)is a widely used method to determine cardiac output (CO). Itis increasingly criticized because of its invasiveness and itsunclear risk–benefit ratio. Thus, less invasive techniquesfor measuring CO are highly desirable. We compared a new, semi-invasivedevice (FloTrac/Vigileo^TM) using arterial pressure waveformanalysis for CO measurement in patients undergoing cardiac surgerywith bolus thermodilution measurements. METHODS: Forty patients undergoing coronary artery bypass grafting orvalve repair were enrolled. A PAC was inserted and routine radialarterial access was used for semi-invasive determination ofCO with the Vigileo. CO was measured simultaneously by bolusthermodilution and the Vigileo technique after induction ofanaesthesia (T1), before cardiopulmonary bypass (CPB) (T2),after CPB (T3), after sternal closure (T4), on arrival in theintensive care unit (ICU) (T5), and 4 h (T6), 8 h(T7), and 24 h after surgery (T8). CO was indexed to thebody surface area (cardiac index, CI). RESULTS: A total of 244 pairs of CI measurements were analysed. Biasand precision (1.96 SD of the bias) were 0.46 litre min^–1m^–2 and ± 1.15 litre min^–1 m^–2 (r =0.53) resulting in an overall percentage error of 46%. Subgroupanalysis revealed a percentage error of 51% for data pairs obtainedintraoperatively (T1–T4), 42% in ICU (T5–T8), and56% for values obtained during low CI (T1–T8). CONCLUSIONS: In cardiac surgery patients, CO measured by a new semi-invasivearterial pressure waveform analysis device showed only moderateagreement with intermittent pulmonary artery thermodilutionmeasurement.     

Epidural magnesium reduces postoperative analgesic requirement

Background: Magnesium has antinociceptive effects in animal and human modelsof pain. Our hypothesis was that the addition of magnesium topostoperative epidural infusion of fentanyl may decrease theneed for fentanyl. Methods: Fifty patients undergoing hip surgery were enrolled to receiveeither fentanyl (Group F) or fentanyl plus magnesium sulphate(Group FM) for 24 h for epidural analgesia. All patients wereequipped with a patient-controlled epidural analgesia deviceand the initial settings of a demand bolus dose of fentanyl25 µg. In Group FM, patients received 50 mg magnesiumsulphate epidurally as an initial bolus dose followed by a continuousinfusion of 100 mg day^–1. Ventilatory frequency, heartrate, blood pressure, pain assessment using a visual analoguescale (VAS), sedation scores and fentanyl consumption were recordedin the postoperative period. Results: There was no significant difference between groups in the timeto first analgesic requirement. Compared with Group F, patientsin Group FM received smaller doses of epidural fentanyl (P <0.05). The cumulative fentanyl consumption in 24 h was 437 (SD110)µg in Group F and 328 (121) µg in Group FM (P <0.05). Patients in Group F showed a higher VAS score in thefirst hour of the postoperative period (P < 0.05). The groupswere similar with respect to haemodynamic and respiratory variables,sedation, pruritis, and nausea. Conclusion: Co-administration of magnesium for postoperative epidural analgesiaresults in a reduction in fentanyl consumption without any side-effects.     

Effects of intrathecal and i.v. small-dose sufentanil on the median effective dose of intrathecal bupivacaine for Caesarean section

Background: Spinal anaesthesia with bupivacaine combined with sufentanilhas been widely used for Caesarean section. However, the mainsite of action (spinal vs central) of intrathecal (IT) sufentanilis controversial. The aim of this study was to examine the predominantmechanism of action of IT, small-dose sufentanil when addedto bupivacaine for Caesarean section, by comparing the effectsof IT and i.v. sufentanil 2.5 µg on the median effectivedose (ED₅₀) of bupivacaine. Methods: Ninety parturients undergoing elective Caesarean section witha combined spinal–epidural technique were enrolled intothis prospective, double-blind, up-down sequential allocationstudy. According to the up-down sequential allocation, parturientsreceived varying doses of bupivacaine alone (C group) or co-administeredwith i.v. sufentanil 2.5 µg group (IVS group; n = 30)or IT sufentanil 2.5 µg group (ITS group; n = 30). Thepossible maternal or neonatal adverse effects were also recorded. Results: The ED₅₀ of bupivacaine was 6.3 mg (95% CI 6.2–6.5) inthe C group, 5.2 mg (95% CI 5.1–5.4) in the IVS group,and 3.0 mg (95% CI 2.9–3.1) in the ITS group. The ED₅₀in the ITS group was significantly lower as compared with theother two groups (P < 0.0005). With the exception of pruritusthat exclusively occurred in the ITS group (P = 0.011, comparedwith the other two groups), no significant differences amonggroups were observed regarding the frequencies of the maternalor neonatal adverse effects. Conclusions: Compared with an equal dose of sufentanil i.v., intrathecallyadministered sufentanil 2.5 µg has a significant localanaesthetic-sparing effect via a predominantly spinal mechanismfor Caesarean section.     

Effect of epinephrine on epidural, intrathecal, and plasma pharmacokinetics of ropivacaine and bupivacaine in sheep

BACKGROUND: Local vasoconstriction induced by epinephrine added to epidural local anaesthetics has been shown to improve their quality and duration of action in several clinical reports. There are several assumptions on the mechanisms. This study was designed to evaluate the influence of epinephrine on transmeningeal uptake of epidurally administered ropivacaine and bupivacaine by measuring local anaesthetic concentrations in the epidural and intrathecal spaces and in plasma. METHODS: Ropivacaine (50 mg) and bupivacaine (30 mg) were administered epidurally in sheep with and without epinephrine (75 microg). A microdialysis technique was used to simultaneously measure epidural and intrathecal drug concentrations. Resulting dialysate and plasma concentrations were used to calculate pharmacokinetic parameters for ropivacaine and bupivacaine. RESULTS: Co-administration of epinephrine decreased epidural clearance for ropivacaine [0.6 (sd 0.1) vs 0.4 (0.1) ml min(-1)] but not significantly for bupivacaine [1.2 (0.4) vs 0.8 (0.3) ml min(-1)]. The resultant increase in epidural area under the concentration-time curves (31% for ropivacaine and 52% for bupivacaine) was also observed in the intrathecal space (21% increase for ropivacaine and 37% for bupivacaine). There was no significant influence of epinephrine on ropivacaine plasma pharmacokinetics. Plasma Cmax for bupivacaine was decreased. CONCLUSIONS: These results show that epinephrine decreases the clearance and distribution processes involved in epidural disposition of ropivacaine and bupivacaine, leading to an increased uptake into the intrathecal space with an apparent more pronounced effect for bupivacaine.     

Measurement of cardiac output: a comparison between transpulmonary thermodilution and uncalibrated pulse contour analysis

Background: Recently, continuous monitoring of cardiac output (CO) basedon pulse contour analysis (Vigileo^®) has been introducedinto practice. In this clinical study, we evaluated the accuracyof this system by comparing it with the transpulmonary thermodilutiontechnique (TPID) in septic patients. Methods: We studied 24 mechanically ventilated patients with septic shock(16 male, 8 female, age 26–77 yr) receiving treatmentwith norepinephrine who for clinical indication underwent haemodynamicmonitoring by the transpulmonary thermodilution technique usinga PiCCO^®plus system (Pulsion Medical Systems, Munich, Germany).In parallel, arterial pulse contour was applied using the femoralarterial pressure curve (FloTrac^® pressure sensor, Vigileo^®monitor, Edwards Lifesciences, Irvine, USA). After baselinemeasurement, mean arterial pressure was elevated by increasingnorepinephrine dosage, and CO was measured again before meanarterial pressure was reduced back to baseline levels. Fluidstatus and ventilator settings remained unchanged throughout.At each time point, CO by transpulmonary thermodilution wascalculated from three central venous bolus injections of 15ml of saline (<8°C). Linear regression and the Bland–Altmanmethod were used for statistical analysis. Results: Overall, CO was 6.7 (SD 1.8) (3.2–10.1) litre min^–1for CO(TPID) and 6.2 (2.4) (3.0–17.6) litre min^–1for CO(Vigileo^®). Linear regression revealed: CO(Vigileo^®)= 1.54 + 0.72 x CO(TPID) litre min^–1, r² = 0.26 (P <0.0001). Mean bias between techniques [CO(TPID)–CO(Vigileo^®)]was 0.5 litre min^–1 (SD 2.3 litre min^–1). Correlationcoefficients at the three time points were not significantlydifferent from each other. Conclusions: Pulse contour analysis-derived CO (Vigileo^® system) underestimatesCO(TPID) and is not as reliable as transpulmonary thermodilutionin septic patients.     

Sciatica: a review of history, epidemiology, pathogenesis, and the role of epidural steroid injection in management

Radicular pain in the distribution of the sciatic nerve, resultingfrom herniation of one or more lumbar intervertebral discs,is a frequent and often debilitating event. The lifetime incidenceof this condition is estimated to be between 13% and 40%. Fortunately,the majority of cases resolve spontaneously with simple analgesiaand physiotherapy. However, the condition has the potentialto become chronic and intractable, with major socio-economicimplications. This review discusses the history, epidemiology,pathophysiology, and natural history of sciatica. A Medlinesearch was performed to obtain the published literature on thesciatica, between 1966 and 2006. Hand searches of relevant journalswere also performed. Epidemiological factors found to influenceincidence of sciatica included increasing height, age, geneticpredisposition, walking, jogging (if a previous history of sciatica),and particular physical occupations, including driving. Theinfluence of herniated nucleus pulposus and the probable cytokine-mediatedinflammatory response in lumbar and sacral nerve roots is discussed.An abnormal immune response and possible mechanical factorsare also proposed as factors that may mediate pain. The ongoingissue of the role of epidural steroid injection in the treatmentof this condition is also discussed, as well as potential hazardsof this procedure and the direction that future research shouldtake.