Post-delivery postural headache: not always a classical post-dural puncture headache.

We report a parturient complaining of headache after spinal and epidural labour analgesia with neurological deterioration following an epidural blood patch. Further investigation revealed a medulloblastoma within the fourth ventricle. The patient underwent an operation 4 days after the diagnosis, but died 2 years later. The consequences of the use of neuraxial analgesia and epidural blood patch in the treatment of post-dural puncture headache in this kind of pathology are discussed.

Urinary bladder scanning after day-case arthroscopy under spinal anaesthesia: comparison between lidocaine, ropivacaine, and levobupivacaine.

BACKGROUND: Micturition problems after spinal anaesthesia may delay hospital discharge. The use of lidocaine has raised concerns because of the occurrence of transient neurological symptoms (TNS). This randomized double-blind study was designed to compare the newer local anaesthetics with lidocaine regarding block characteristics, micturition problems, and discharge times in day-case spinals for arthroscopy. METHODS: Ninety patients received either isobaric lidocaine 60 mg, ropivacaine 15 mg, or levobupivacaine 10 mg intrathecally. Urinary bladder volumes were measured by ultrasound imaging at regular time intervals until a post-voiding residual volume (PVRV) less than 100 ml was obtained. Micturition problems were classified in five groups ranging from no problems to those requiring catheterization. RESULTS: Times to regain a Bromage-1 and -0 motor block were similar in the three groups but sensory block regression to L2 occurred at 145 (30) min in the lidocaine group, 25-30 min (P<0.05) faster than the other groups. Lidocaine allowed voiding after 245 (65) min and hospital discharge 265 (70) min after spinal injection, 40 min faster than in the two other groups. The incidence or degree of micturition problems were not different between after discharge, three patients (10%) receiving lidocaine complained of symptoms compatible with TNS. CONCLUSIONS: Our study suggested that the three local anaesthetics behave similar regarding quality of anaesthesia and motor block but voiding and discharge occurred significantly earlier with lidocaine although the 40 min difference was not impressive considering a spinal discharge time interval of 4-5 h.

Target controlled infusion of rocuronium: analysis of effect data to select a pharmacokinetic model.

BACKGROUND: We aimed to evaluate whether area under the curve (AUC) analysis of pharmacodynamic data can be used to compare pharmacokinetic models taken from the literature, during a target controlled infusion (TCI) of rocuronium. METHODS: Seventy-two patients scheduled for orthopaedic surgery received a TCI of rocuronium (Stanpump) based on one of four pharmacokinetic models: those described by Szenohradszky, Alvarez-Gomez, Wierda, and Cooper. The resulting theoretical plasma concentration versus time curve was calculated for all patients based on all four pharmacokinetic models. Predicted effect versus time curves were calculated following the pharmacokinetic-pharmacodynamic link model (Sheiner and colleagues). Neuromuscular block was evaluated acceleromyographically. The difference between the area under the observed effect (AUC(OE)) and predicted effect (AUC(PE)) versus time curves was used for comparison. RESULTS: AUC(PE )differed significantly from AUC(OE) in the Szenohradszky and Alvarez-Gomez models, both with the reference link-pharmacodynamic data and with altered link-pharmacodynamic variables. AUC(PE )and AUC(OE) were comparable for the Wierda and Cooper models. The mean AUC(OE) was 25.1 (SD 11.9)% block x h. AUC(PE)-AUC(OE) was significantly larger in the Szenohradszky model when compared with all other pharmacokinetic models. This difference remained when link or pharmacodynamic variables were modified. The smallest AUC(PE)-AUC(OE) difference was found with the Wierda model. CONCLUSION: It was possible to use AUC analysis for identification of the pharmacokinetic model that best predicted the pharmacodynamic characteristics of our patients.

Interactions of NMDA antagonists and an alpha 2 agonist with mu, delta and kappa opioids in an acute nociception assay.

Animal and clinical studies have reported potentiation of opioid antinociception by co-administration of alpha-2 adrenoceptor agonists such as clonidine and NMDA receptor antagonists such as ketamine and dextromethorphan. The aim of this study was to compare these clinically available compounds in combination with classical morphine, fentanyl-like opioids, the delta opioid agonist SNC80 and the kappa opioid agonist U50,488H. Using a mouse hot-plate test, dose-response relationships were first determined for all compounds individually and then for opioids co-administered with fixed doses of clonidine, ketamine or dextromethorphan. Clonidine was also evaluated in combination with ketamine and dextromethorphan. ED50 values were calculated from the proportion of animals reaching a fixed cut-off criterion of 30 s. To varying degrees, all compounds produced increases in response latencies over time. Dextromethorphan produced lower ED50 values for morphine, fentanyl and sufentanil but exerted no effect on SNC80 or U50,488H. Similarly, ketamine potentiated the antinociceptive efficacy of morphine and sufentanil but not SNC80 or U50,488H. By contrast, clonidine potentiated all opioids tested. In addition, the potency of clonidine was found to increase with co-administration of ketamine but not dextromethorphan. The strongest opioid sparing interactions occurred between clonidine and the lipophilic mu opioids fentanyl and sufentanil and the delta opioid SNC80. In summary, these results suggest an important role for lipophilic opioids in combination therapies particularly with clonidine as well as possible advantages of specific delta or kappa opioid combinations with alpha-2 agonists.

Postoperative analgesia with i.v. patient-controlled morphine: effect of adding ketamine.

We have studied the effect of adding ketamine to i.v. morphine patient-controlled analgesia (PCA) for the treatment of pain after laparotomy. Thirty patients were allocated randomly to receive PCA with saline or ketamine in a double-blind, randomized study. Analgesia was started in the recovery room when visual analogue scale (VAS) scores were > 4. A bolus dose of morphine 3 mg was given to all the patients followed by i.v. PCA. Simultaneously, an infusion of ketamine 2.5 micrograms kg-1 min-1 or saline was started. Pain scores, morphine consumption and side effects were noted for up to 48 h after the start of PCA. VAS scores decreased significantly with time (P = 0.0001) and were similar (P = 0.3083) in both groups. Cumulative morphine consumption at 48 h was significantly lower in the ketamine group (28 mg) than in the control group (54 mg) (P = 0.0003). Nausea was less frequent in the ketamine group (P = 0.03).

Posterior epidural space depth: safety of the loss of resistance and hanging drop techniques.

We have compared skin to epidural space distance (SED) and tip to tip distance (TTD), a measure of posterior epidural space depth (PESD), in 40 patients with a 27-gauge Whitacre needle after identification of the epidural space using the hanging drop (HD) or loss of resistance (LOR) to air technique. After the LOR technique, TTD was found to be 2 mm greater than that after the HD technique, whereas SED was the same. We conclude that identification of the epidural space can be performed successfully with both techniques, but with a diminished risk of dural damage after LOR compared with the HD technique.

Small-dose hyperbaric versus plain bupivacaine during spinal anesthesia for cesarean section.

UNLABELLED: In a double-blind, randomized trial, 98 parturients undergoing cesarean section received either hyperbaric or plain bupivacaine 6.6 mg combined with sufentanil 3.3 microg as part of a combined spinal-epidural procedure. To prevent hypotension, 1000 mL of lactated Ringer's solution, 500 mL of hydroxyethyl starch 6%, and ephedrine 5 mg were administered i.v. The height of the block was equal in both groups, but more patients in the plain group had blocks that were either too high or too low (P < 0.01). The number of patients requiring epidural supplementation was equal in both groups. Strict criteria were used to treat hypotension. The overall incidence of systolic blood pressure (<90 mm Hg) was 13%, whereas it was more pronounced in the plain group (21% vs 6% in the hyperbaric group, P < 0.05), which required more ephedrine (P < 0.05) and in which a greater incidence of nausea was noticed (P < 0.05). We conclude that the use of a small dose of intrathecal bupivacaine combined with sufentanil plus our described preloading regimen resulted in a lower incidence of hypotension. Further, we conclude that the use of hyperbaric bupivacaine in this manner provides a more reliable block and a lower incidence of hypotension than plain bupivacaine. IMPLICATIONS: A small dose of hyperbaric bupivacaine 0.5% combined with sufentanil used intrathecally during cesarean section offered a more reliable cephalad spread of the spinal block than the glucose-free combination, which was reflected in a lower incidence of hypotension and nausea.

Addition of bupivacaine to sufentanil in patient-controlled epidural analgesia after lower limb surgery in young adults: effect on analgesia and micturition.

BACKGROUND AND OBJECTIVES: The usefulness of adding bupivacaine to an opioid administered by the epidural route is controversial. This study examines both the quality of pain relief and side effects, in particular urinary retention, during patient-controlled epidural analgesia (PCEA) with sufentanil alone or in combination with two different concentrations of bupivacaine. METHODS: In a double-blind randomized study, 60 healthy young adults undergoing open knee or ankle surgery with combined spinal-epidural anesthesia received postoperative analgesia via PCEA with sufentanil alone or with 0.06% or 0.12% bupivacaine. In addition to pain scores at rest and during mobilization, bladder function was evaluated. Strict criteria were respected in scoring the occurrence of problems suggestive of urinary retention. The 24-hour analgesic consumption and the incidence of other side effects were also recorded. RESULTS: Patients receiving bupivacaine had better pain relief than those receiving only the opioid, but this difference was more pronounced when measuring dynamic pain scores. The consumption of sufentanil was significantly higher in the group receiving the opioid alone than in the group receiving 0.06% bupivacaine. The bupivacaine dose requirements were twice as high with the 0.12% concentration. Bladder problems occurred significantly more frequently in patients treated with the highest bupivacaine concentration. Motor impairment was not a major problem. CONCLUSIONS: A 0.06% bupivacaine-sufentanil combination offered the best results in terms of analgesic quality and lower side effects, mainly micturition problems, which may be explained by the higher consumption of local anesthetic at the higher bupivacaine concentration. Analgesic quality could not be improved by increasing the bupivacaine concentration.

Postoperative intrathecal patient-controlled analgesia with bupivacaine, sufentanil or a mixture of both.

In a randomised double-blind study, 45 patients, scheduled for major orthopaedic surgery under continuous spinal anaesthesia, received for relief of postoperative pain patient-controlled analgesia with either sufentanil 2 micrograms.ml-1, bupivacaine 0.0625% or a mixture of both by the intrathecal route. The mean (SD) consumption of sufentanil and bupivacaine during the first 12 h was 65.5 (27.1) micrograms and 18.2 (4.8) mg, respectively. Combining bupivacaine and sufentanil reduced the consumption of both to approximately 40% as compared to the administration of each component separately. Pain relief was very good in all subjects, although this was obtained faster with the combined regimen. Moreover, more patients in this group remained completely painfree during the entire observation period (p < 0.05). The incidence of hypotension was low and not significantly different when the plain bupivacaine group was compared with the two other groups. Nausea and vomiting were significantly more frequently observed in both groups treated with sufentanil. Motor block was not a major problem and was noticed during the first 2 h of treatment only. Tachyphylaxis did not occur. It was concluded that the groups receiving plain bupivacaine and sufentanil alone experienced pain relief of good quality. The use of a mixture, however, accelerated the onset of analgesia, improved the analgesic quality and reduced the doses for both components by 60% but at the expense of a higher incidence of nausea and vomiting.

A new combined spinal-epidural apparatus: measurement of the distance to the epidural and subarachnoid spaces.

A new combined spinal-epidural anaesthesia apparatus with a 27G lockable spinal needle was used in 151 patients. Two groups could be created, based on whether dural perforation was felt or not (group 1: with dural click; group 2: no dural click). Measurements of the epidural space depth and of the protrusion of the spinal needle from the epidural needle (tip-to-tip distance) were made. The mean depth of the epidural space was 5.59 cm. Correlations were found with body weight, weight-to-height ratio and body mass index (p < 0.001). The mean tip-to-tip distance measured was 7.0 mm in the patients of group 1, whereas in group 2 a distance of 8.9 mm was found. This difference was statistically significant. Correlations were found between the epidural space width and the patient's height, weight-to-height ratio and body mass index. Four patients felt paraesthesia during placement of the spinal needle and, in another four patients, aspiration was necessary to detect cerebrospinal fluid. Two patients needed epidural top-ups due to insufficient level of anaesthesia. The lockable spinal needle provides safe and stable conditions during injection and a high rate of success in reaching the subarachnoid space.

Ausência de anticorpos contra o vírus da doença de Aujeszky em suínos no Estado do Rio Grande do Sul / Absence of antibodies to Aujeszky virus in swine in the State of Rio Grande do Sul, Brazil

A serological survey was carried out on 16.305 swine sera collected over a eight year period (1987-1994) from various municipalities of the State of Rio Grande do Sul, Brazil, in search for antibodies to Aujeszky's disease virus (ADV), using ELISA and serum neutraliozation tests. All sera examined were negative for ADV antibodies. These results suggest that ADV is not present in an enzootic form in swine in that State

Central-to-peripheral arterial pressure gradient during cardiopulmonary bypass: relation to pre- and intra-operative data and effects of vasoactive agents.

A significant central-to-peripheral arterial pressure gradient may exist during and after cardiopulmonary bypass (CPB). The etiology and mechanisms of this phenomenon remain controversial. We studied the pressure gradient between aorta, brachial artery and radial artery in 68 patients, scheduled for elective coronary artery bypass surgery. We evaluated whether choice of cardioprotection during CPB (use of cold cardioplegic solution or use of intermittent crossclamping under protection with lidoflazine), and choice of pulsatile or nonpulsatile flow during the course of CPB, affected the magnitude and duration of the systolic pressure gradient. We also studied whether central-to-peripheral pressure gradient was influenced by administration on CPB of different vasoactive drugs with different mode of action: sodium nitroprusside (direct action on the vessels), droperidol (alpha-adrenergic blocking action), ketanserin (5-hydroxytryptamine antagonist) and phenylephrine (selective alpha 1-agonist). It appeared that central-to-peripheral gradient occurred early during CPB and remained constant throughout the course of CPB. The gradient disappeared within 60 min after weaning from CPB. We found the main pressure gradient to occur between the brachial and the radial artery. There was no relation between magnitude of the gradient and sex, weight, length or age of the patient. There was also no relation between magnitude of the pressure gradient and type of cardioprotection, choice of pulsatile vs nonpulsatile flow on CPB and duration of CPB. We also found no relation between pressure gradients and changes in temperature, haematocrit and systemic vascular resistance. The pressure gradient was not affected by any of the vasoactive drugs.