Postoperative patient-controlled thoracic epidural analgesia: importance of dose compared to volume or concentration.

This randomised and blinded study evaluated the quality of analgesia and the incidence of side-effects of two concentrations of levobupivacaine (0.15% and 0.5%) given as an equal mg-bolus-dose (5 mg) via patient-controlled epidural analgesia after lower abdominal surgery. The patients were randomly assigned into two groups to receive either 0.15% levobupivacaine as a 3.3 ml bolus on demand, with a lockout interval of 30 minutes (n=30), or 0.5% levobupivacaine as a 1 ml bolus on demand, with a similar lockout interval (n=30). For both groups we combined the bolus on demand with a background infusion of 5 mg/hour levobupivacaine, i.e. 3.3 ml/hour 0.15% or 1 ml/hour 0.5% of levobupivacaine. The epidural catheters were inserted in a lower thoracic intervertebral space before induction of general anaesthesia. The following variables were registered in the 48 hours after surgery: upper and lower sensory block, pain scores at rest and after coughing, rescue morphine consumption, motor blockade, haemodynamic (arterial blood pressure and heart rate), nausea and vomiting, and patient satisfaction ratings. The two groups had similar sensory block, quality of analgesia, rescue morphine consumption requirement, motor blockade and side-effects, and both had a high satisfaction rate. These findings indicate that administering the same dose of levobupivacaine in either a low or high concentration via the patient-controlled epidural analgesia mode, combined with a background infusion, provides an equal quality of analgesia for low thoracic level epidurals with no difference in the incidence of side-effects.

Low vs. high concentration of levobupivacaine for post-operative epidural analgesia: influence of mode of delivery.

BACKGROUND: Although the use of continuous epidural infusion (CEI) and patient-controlled epidural analgesia (PCEA) has become commonplace in pain management, there is still controversy regarding the relative effects of mass, volume and concentration of the local anaesthetic. This prospective study evaluated the influence of two concentrations of levobupivacaine on the quality of analgesia in two modes of delivery after lower abdominal surgery. METHODS: Eighty-two patients were randomly assigned to four groups to receive combined low thoracic epidural analgesia and general anaesthesia followed by post-operative CEI or PCEA using 1.5 or 5 mg/ml levobupivacaine (15 mg/h in CEI and bolus 5 mg, lockout 20 min in PCEA). Sensory block, pain scores, levobupivacaine and rescue morphine consumption, motor blockade, haemodynamics, side-effects and patient satisfaction were registered within 48 h. RESULTS: The four groups were similar with regard to demographics, quality of analgesia, morphine consumption and satisfaction rate. No difference in the quality of analgesia was observed for the two modes of delivery with regard to the concentration of levobupivacaine, but the consumption of the local anaesthetic was higher in the CEI groups. The Bromage scores in the PCEA groups were reduced to zero for all except one patient, whereas eight patients presented scores of one or more in the CEI population. CONCLUSION: Levobupivacaine in thoracic epidurals provides an equal quality of post-operative analgesia in low and high volume independent of the delivery mode, i.e. CEI or PCEA. This is in accordance with the assumption that the total dose of the local anaesthetic determines the quality of analgesia.

Tropisetron in the prevention of postoperative nausea and vomiting.

STUDY OBJECTIVES: To evaluate the efficacy of tropisetron, a selective 5-HT(3) receptor antagonist, in preventing nausea and vomiting in high-risk inpatients undergoing various surgical procedures. DESIGN: Prospective, open, nonrandomized, observational, interventional study. SETTING: Postanesthesia care unit, and surgical wards of the University Hospital Center, Charleroi. PATIENTS: A total of 1,132 elective surgical inpatients (>15 years of age) in two separate surveys. The first prospective survey covered all surgical adult inpatients (n = 671) after various surgical procedures over a 3-month period. A new 3-month survey was performed to assess the effectiveness of the preventive measure and included another 461 patients. INTERVENTIONS: Risk factors associated with nausea and vomiting were recorded in the first survey and used to establish an antiemetic policy. This consisted in the administration of tropisetron 2 mg intravenously after anesthesia induction, if two patient-related risk factors associated with high-risk surgery and general anesthesia were present. MEASUREMENTS AND MAIN RESULTS: Nausea frequency and intensity, assessed every 4 hours using a visual analog scale (VAS), frequency and times of vomiting episodes and the need for rescue medication were recorded for 72 hours postoperatively. Nausea was experienced by 18.8% and vomiting by 9.8% of the patients in the first survey (211 high risk-patients of 671). In the second survey, 137 patients of 461, considered at high-risk received prophylactic tropisetron. The proportion of patients having nausea decreased to 11.1% (p,178 0.01) and vomiting episodes to 2.8% (p < 0.001). Twenty-six of the tropisetron-treated patients (19%) suffered subsequent postoperative nausea and vomiting (PONV). Patient satisfaction with tropisetron was high. CONCLUSION: Prophylactic tropisetron can reduce the incidence of PONV in selected high-risk inpatients undergoing various types of surgical procedures.

Assessment of postoperative nausea using a visual analogue scale.

BACKGROUND: Assessment of postoperative nausea intensity is difficult because nausea is a subjective and unpleasant sensation. We propose using the Visual Analogue Scale (VAS) device to increase the efficiency and precision in the assessment of nausea. We carried out a pilot study on postoperative patients suffering from nausea to measure the degree of agreement between the VAS scores and those given on a 4-point verbal descriptive scale (VDS). METHODS: Postoperative nausea was evaluated by means of a classical VAS (0-10 cm) device and a 4-point VDS (0=no nausea, 1=mild, 2=moderate, 3=severe) in 128 surgical spontaneously complaining patients. Evaluation was repeated 45 min after rescue medication given if nausea was intractable, lasted more than 10 min or at the request of the patient. Ordinal logistic regression was used to measure the association between VAS and VDS and to determine cut-off points on the VAS. RESULTS: The VAS device was easily understood and used by patients. VAS scores decreased significantly from 5.5+/-2.3 to 1.4+/-1.8 after rescue medication (P=0.002). Application of ordinal logistic regression to pre- and post-medication data combined yielded an agreement of 86% between VAS and VDS and the cut-off points on the VAS were estimated as follows: 0-1 (no nausea), 1+/-4 (mild), 4+/-7 (moderate) and 7+/-10 (severe). CONCLUSION: The VAS method proved to be useful for assessing quantitative nausea intensity and for testing the efficacy of rescue medication. It was found that a cut-off value of 4 on the VAS may be considered as a critical threshold triggering anaesthesiologists or nurses to administer rescue medication.

Lower limb exsanguination and embolism.

We report a case of fatal pulmonary embolism during lower limb exsanguination in orthopaedic surgery. A 76-year-old woman underwent an open fixation of an external femoral condyle fracture one day after injury. Subarachnoidal anaesthesia was performed and Esmarch compression bandages were applied in preparation for tourniquet ischaemia. At this time, the patient lost consciousness, became apneic and collapsed. Resuscitation procedures were instituted and transoesophageal echocardiography revealed pulmonary embolism. In spite of haemodynamic support and thrombolytic therapy, the patient died. Postmortem examination revealed multiple thromboemboli of recent origin in the right heart cavities, in the pulmonary arteries and in the popliteal and tibial veins of the injured leg. Preventive, diagnostic and therapeutic options of this catastrophic event and indications of pulmonary embolectomy are discussed.

Assessment of the postoperative residual curarisation using the train of four stimulation with acceleromyography.

The aim of this study was to measure the incidence of patients with train of four ratio < 0.9 in the immediate postoperative period using acceleromyography. At arrival in recovery room, 257 patients were enrolled. Train of four ratio was assessed at the adductor pollicis using TOF-GUARD INMT apparatus. Patients were divided in two groups according to TOF ratio < (group 1) or > (group 2) to 0.9. Demographic variables, dose (mg), dose/weight ratio (mg.kg-1) of atracurium and surgery duration (min) were registered. There was no difference in demographic variables, duration of surgery (100.90 +/- 67.38/94.83 +/- 62.42 min), number of incidence reversal of neuromuscular block. Patients in group 1 (n = 72) received a higher dose (54.58 +/- 38.03/41.43 +/- 19.47 mg) of atracurium compared to group 2 (n = 176). Thirty percent of patients presented a train of four ratio < 0.7 and 13% < 0.9. TOF-GUARD INMT was easy to use.

Effectiveness of an acute pain service inception in a general hospital.

STUDY OBJECTIVES: To assess the effects of an Acute Pain Service (APS) inception on postoperative pain management in a general teaching hospital using pain indicators as performance measures. DESIGN: Open, prospective, nonrandomized, observational study. SETTING: Postanesthesia Care Unit, surgical wards of University Hospital Center of Charleroi. PATIENTS: 1304 patients in the pre-APS inception phase and 671 patients after its implemention who have undergone various types of surgery (orthopedics, gynecology, urology, neurosurgery, stomatology, ear, nose, and throat, ophthalmic, abdominal, vascular-thoracic, plastic, and maxillofacial). INTERVENTIONS: An APS, nurse-based, anesthesiologist-supervised model was devised, based on the concept that postoperative pain relief can be greatly improved by providing in-service training for surgical nursing staff and optimal use of systemic analgesics. MEASUREMENTS AND MAIN RESULTS: Postoperative pain was assessed using a visual analog scale (VAS) every 4 hours for 72 hours in the two phases. Analgesic consumption was registered at the same time. Time-related VAS scores were summarized using several pain indicators. There was an overall improvement in the pain scores after APS inception. The differences were most pronounced, around 50%, in patients undergoing vascular, maxillofacial, gynecologic, and urologic surgeries, and stomatology. Regular administration of paracetamol and nonsteroidal antiinflammatory drugs decreased morphine consumption in the second phase. CONCLUSION: This study validates the benefits of a formal APS, using continuous monitoring of rest pain intensity and analgesic consumption in the postoperative period. Results not only support previous research findings but also offer outcome-based tools to evaluate current practices as compared with desired outcomes.

Clinical features and echocardiography of embolism during cemented hip arthroplasty.

PURPOSE: In previous studies the degree of embolization detected by transoesophageal echocardiography (TEE) during cemented total hip arthroplasty (THA) did not correlate with changes in haemodynamic variables nor did it result in persistent ventilation-perfusion mismatching. The aim of this study was to record evidence of embolism and to relate the findings to demographic data and the subsequent clinical course of the patients during THA. METHOD: Forty-eight patients scheduled to undergo elective cemented THA during general anaesthesia were monitored. A TEE probe was inserted with special attention to the right atrium (RA), the right ventricle (RV) Haemodynamic (heart rate, arterial blood pressure, central venous pressure) and blood-gas variables were measured repeatedly during the operative procedure (after induction, placement of the acetabular component, placement of the femoral component, relocation of the hip joint). Grading of venous embolism at these times was based on the size of particles detected by TEE (three-minutes video segments of each periods) and correlated with demographic, haemodynamic and blood-gas data. RESULTS: The TEE monitoring revealed showers of echogenic material traversing the RA and RV in all but one patients during reaming and cementing of the acetabular and femoral components, and during relocation of the hip joint. No correlation was observed between frequency or size of embolic particles and demographic or blood-gas and haemodynamic variables studied at the same times. CONCLUSION: This study failed to show any clinical impact of TEE detected emboli during cemented THA.

Use of liposome-associated bupivacaine in a cancer pain syndrome.

Bupivacaine 0.25% encapsulated by multilamellar liposomes was administered epidurally to a patient suffering pain associated with lung cancer and the effect compared with a plain bupivacaine solution of the same concentration. Complete analgesia was produced for 4 h with the plain solution and 11 h with the liposomal formulation. No motor blockade or haemodynamic instability was observed with the liposome-associated bupivacaine.

Biodistribution of liposomes after extradural administration in rodents.

We have mapped over 24 h the biodistribution of 99mTc-labelled multilamellar and small unilamellar liposomes in rabbits and rats by scintigraphic imaging after extradural injection. Multilamellar vesicles formed a depot at the site of injection; small unilamellar vesicles spread immediately along the extradural space and entered the systemic compartment 30 min after injection. Well-delineated liver and kidney labellings were seen after 24 h. The use of 3H-cholesterol-labelled small unilamellar vesicles suggested hepatic capture of intact liposomes with sizes averaging 0.05 microns drained unmodified into the systemic circulation through the extradural lymphatics. These results have led to the selection of multilamellar vesicles (0.1-15 microns size range) for clinical trials using liposome-associated local anaesthetics.

Biodistribution of liposome-associated bupivacaine after extradural administration to rabbits.

After one extradural injection of 0.25% bupivacaine 0.3 ml and 3H-bupivacaine 0.005 mCi in multilamellar liposomes, no systemic radioactivity (plasma, liver, heart muscle) was obtained for 1 h, and the labelling was less than that of systemic distribution of plain bupivacaine for the following 3 h. In contrast, radioactivity in the lumbar spinal nerves peaked in the first hour and remained higher than that of plain bupivacaine for 4 h. No radioactivity was measured in cerebrospinal fluid. Small unilamellar vesicles incorporating 3H-cholesterol did not significantly label spinal nerves and central nervous structures indicating that the mode of action of liposomal bupivacaine did not involve uptake by nerve structures. Rapid uptake of radioactivity by spinal nerves suggested exchange of bupivacaine between liposomes and nerve sheaths.

Embolism detected by transoesophageal echocardiography during hip arthroplasty.

This case report demonstrates embolization of echogenic material detected by transoesophageal echocardiography during a cemented total hip arthroplasty in a 76-yr-old woman without patent foramen ovale. During the placement of the acetabular and femoral components, and during relocation of the hip joint, a "snow flurry" appearing in the right atrium was followed by several highly echogenic and mobile emboli of various sizes, some of them with a vermiform shape 1 to 5 cm long. At skin closure, echogenic material was seen in the right branch of the pulmonary artery adherent to the vascular wall of the bifurcation of the main pulmonary artery. No changes were observed in any haemodynamic variable monitored (heart rate, systemic and right atrial pressures). Also, no desaturation was detected by pulse oximetry and blood gases at the time of embolism and there was no decrease in PETCO2. This case report is in line with other studies which failed to show a haemodynamic impact of TEE detected emboli during THA.

Epidural administration of liposome-associated bupivacaine for the management of postsurgical pain: a first study.

STUDY OBJECTIVES: To explore the influence of liposomes on the pharmacodynamic action of bupivacaine and to determine whether postsurgical analgesic advantages can be obtained from epidural delivery of liposomal bupivacaine compared with the current formulation. DESIGN: Open, nonrandomized study. SETTING: Physiopathology laboratory, general operating theaters, and intensive care units of Reine Fabiola Hospital and Institut Médical de Traumatologie et Revalidation. PATIENTS: 26 ASA physical status II and III patients who had undergone major surgery (abdominal, vascular, urologic, thoracic, orthopedic). INTERVENTIONS: After completion of the operation, the patients were divided into 2 groups to receive 1 of 2 bupivacaine preparations epidurally for postsurgical pain: Group 1 (n = 12) received plain 0.5% bupivacaine with 1:200,000 epinephrine; Group 2 (n = 14) received liposomal 0.5% bupivacaine. MEASUREMENTS AND MAIN RESULTS: The following observations were made: onset and quality of analgesia, quality of motor block according to the Bromage scale, and sympathetic block. Onset time of sensory block averaged 15 minutes in both groups. Pain relief durations were 3.2 +/- 0.4 hours with plain bupivacaine and 6.25 +/- 1.13 hours with the liposomal preparation (p < 0.05). In the liposomal bupivacaine group, no motor block was recorded. Low sympathetic block occurred in all patients. Analgesia in a subset of patients following abdominal aortic surgery increased from 2.4 +/- 0.35 hours to 10.6 +/- 1.4 hours by encapsulation of bupivacaine (p < 0.01). There was no neurotoxicity or cardiotoxicity. CONCLUSIONS: The liposomal formulation of bupivacaine increased duration of analgesia without motor block or adverse side effects.

Plasma concentrations of bupivacaine after brachial plexus administration of liposome-associated and plain solutions to rabbits.

Bupivacaine has been associated to multilamellar liposomes with the aim of altering circulating plasma concentrations after injection into the rabbit brachial plexus. Plasma concentrations of bupivacaine have been compared after administration of free drug (BP) or bupivacaine associated to multilamellar liposomes (BP-MLV) made of phosphatidylcholine and cholesterol (molar ratio 4:3). Under light general anaesthesia, one group of six rabbits received an axillary injection of 2.5 mg BP (1 ml, 0.25%), and a second received the same dose of BP-MLV. In both groups 3H bupivacaine was used as a marker. The brachial plexus was located using a nerve stimulator. Injection of the anaesthetic solutions invariably prevented the motor response of the paw. The arterial plasma concentrations of bupivacaine were determined after 5 to 240 min and after 24 hr by beta counting. In the MLV population, additional measurements were performed after 48 and 72 hr. The two plasma curves showed a plateau (0.2 microgram.ml-1) which was reached after five minutes in the BP group and after 90 min using BP-MLV. In the BP-MLV group, the plasma concentrations of bupivacaine were lower during the first ten minutes (P < 0.05), and higher after 24 hr (P < 0.05). Radioactivity decreased between 4 and 24 hr in the BP group and between one and two days in the BP-MLV population. It is concluded that elevated plasma drug concentrations were maintained for longer with BP-MLV than with BP. This could prolong the action of the local anaesthetic through a slow release.