Profound motor blockade with epidural ropivacaine following spinal bupivacaine

Ropivacaine, a relatively new amide local anaesthetic, reputedly produces less motor block than equivalent doses of bupivacaine, potentially combining high-quality analgesia with the ability to ambulate. We report two cases of prolonged, profound motor block with patient-controlled epidural analgesia using 0.1% ropivacaine, following spinal bupivacaine for Caesarean section. As there was no evidence of inadvertent intrathecal ropivacaine administration or of any neurological injury, we hypothesise that epidural ropivacaine may interact with intrathecal bupivacaine to prolong its effect.     

Topical bupivacaine and etidocaine analgesia following fallopian tube banding

The purpose of this study was to compare the effectiveness and safety of etidocaine and bupivacaine for postoperative analgesia after laparoscope sterilization. The study was performed in 22 healthy patients who received either one per cent etidocaine, 2 mg.kg-1, or bupivacaine 1.5 mg.kg-1 in a double-blind, randomized fashion. The local anaesthetic was dropped onto the fallopian tubes from uterus to fimbriae before tubal occlusion. To establish safety, blood concentrations of the parent drug and its metabolites were measured before application and at 1, 3, 6, 10, 15, 30, 60 and 120 min. The mean peak concentrations were 501.8 +/- 71.3 (SEM) for etidocaine with a range of 225 to 905 ng.ml-1. For bupivacaine, the mean peak concentration was 468 +/- 73.8 SEM with a range from 191 to 1005 ng.ml-1. The mean values are one eighth of the toxic convulsive dose for humans. Etidocaine was metabolized at a faster rate than bupivacaine with a rapid appearance of 2-amino-2'-butyroxylidide (ABX). The bupivacaine metabolite 2,6-pipecoloxylidide (PPX) was detected in low concentrations in the 60-minute samples. We conclude that the topical application of either etidocaine or bupivacaine is a safe procedure in the doses and concentrations used during general anaesthesia for laparoscopic tubal banding.     

Local Anaesthetics Modifying the Dermal Response of Irradiation: An experimental study

In a series of experiments in rabbits the dermal reaction, provoked by a single dose or intermittent doses of irradiation, was prevented or modified by topical or parenteral administration of local anaesthetics, compared to irradiated control animals. The topical application of a eutectic lidocaine/prilocaine cream, EMLA 5%, was found to be more effective than intravenously injected lidocaine (Xylocain 1%).     

Intervertebral epidural anaesthesia in paediatric surgery: success rate and adverse effects in 650 consecutive procedures

The success rate and occurrence of adverse effects are reported in a retrospective study of 650 (99 sacral, 468 lumbar, 76 thoracic and seven cervical) paediatric epidurals performed, mostly (91%) under light general anaesthesia, by several anaesthetists. Seventeen-gauge Tuohy and 20-gauge (Potts-Cournand® and Tuohy) needles were used. Anaesthetic solutions used were 1% lignocaine, 0.5% bupivacaine and a mixture of equal volumes of 0.5% bupivacaine with either 1% lignocaine or 1% etidocaine, all containing 1:200 000 adrenaline. The epidural space was identified by loss-of-resistance technique (LORT) with normal saline, air or CO₂. Up to five attempts were occasionally necessary. LORT using fluid resulted in more subarachnoidal penetrations than the LORT using air (P < 0.05) which was easy and reliable but produced patchy anaesthesia (‘painful gaps') in 4.2% of patients. CO₂-LORT was as easy and reliable as air-LORT and did not result in painful gaps. Lateral and mid-line insertion routes were equally suitable whatever the level of approach. Twenty-gauge needles, especially Tuohy needles, resulted in significantly less dural punctures in young children. The spread of the local anaesthetic correlated with the volume injected and the height of the epidural approach. Epidural anaesthesia had little haemodynamic effects. Administration of epidural morphine improved the duration of postoperative pain relief but undesirable effects occurred in up to 50% of patients. Low doses of naloxone (2–5 μg?kg^?1.h^?1) counteracted most adverse effects, avoiding urinary retention and delayed apnoea. Anaesthetists and residents without experience in paediatric anaesthesia had a good success rate in performing the techniques (under supervision of an experienced anaesthetist). At the same time, experience in regional anaesthesia would significantly boost the confidence of the anaesthetist in managing such cases. The authors recommend using CO₂ instead of air in the LORT.     

Influence of xenon on pulmonary mechanics and lung aeration in patients with healthy lungs

Background

The anaesthetic xenon shows potent organ-protective properties. Due to high density and dynamic viscosity, peak inspiratory pressure (P_max) increases during xenon application. Thus, barotrauma may counteract organ protection. Accordingly, we investigated the influence of xenon on lung mechanics and lung aeration in patients with normal and reduced thoracic wall compliance.

Apoptotic insults to human HepG2 cells induced by S-(+)-ketamine occurs through activation of a Bax-mitochondria-caspase protease pathway

Background: Ketamine is widely used as an i.v. anaesthetic agent and asa drug of abuse. Hepatocytes contribute to the metabolism ofendogenous and exogenous substances. This study evaluated thetoxic effects of S-(+)-ketamine and possible mechanisms usinghuman hepatoma HepG2 cells as the experimental model. Methods: HepG2 cells were exposed to S-(+)-ketamine. Cell viability andthe release of lactate dehydrogenase (LDH) and -glutamyl transpeptidase(GPT) were measured to determine the toxicity of S-(+)-ketamineto HepG2 cells. Cell morphology, DNA fragmentation, and apoptoticcells were analysed to evaluate the mechanism of S-(+)-ketamine-inducedcell death. Amounts of Bax, an apoptotic protein, and cytochromec in the cytoplasm or mitochondria were quantified by immunoblotting.Cellular adenosine triphosphate levels were analysed using abioluminescence assay. Caspases-3, -9, and -6 were measuredfluorometrically. Results: Exposure of HepG2 cells to S-(+)-ketamine increased the releaseof LDH and GPT, but decreased cell viability (all P<0.01).S-(+)-Ketamine time-dependently caused shrinkage of HepG2 cells.Exposure to S-(+)-ketamine led to significant DNA fragmentationand cell apoptosis (P=0.003 and 0.002). S-(+)-Ketamine increasedtranslocation of Bax from the cytoplasm to mitochondria, butdecreased the mitochondrial membrane potential and cellularadenosine triphosphate levels (all P<0.01). Sequentially,cytosolic cytochrome c levels and activities of caspases-9,-3, and -6 were augmented after S-(+)-ketamine administration(all P<0.001). Z-VEID-FMK, an inhibitor of caspase-6, alleviatedthe S-(+)-ketamine-induced augmentation of caspase-6 activity,DNA fragmentation, and cell apoptosis (all P<0.001). Conclusions: This study shows that S-(+)-ketamine can induce apoptotic insultsto human HepG2 cells via a Bax-mitochondria-caspase proteasepathway. Thus, we suggest that S-(+)-ketamine at a clinicallyrelevant or an abused concentration may induce liver dysfunctionpossibly due to its toxicity to hepatocytes.     

Effect of low-dose ketamine on inflammatory response in off-pump coronary artery bypass graft surgery

Background: Off-pump coronary artery bypass graft surgery (OPCAB) is stillassociated with a marked systemic inflammatory response. Theaim of this study was to investigate whether pre-emptive, lowdose of ketamine, which has been reported to have anti-inflammatoryactivity in on-pump coronary artery bypass surgery, could reduceinflammatory response in low-risk patients undergoing OPCAB. Methods: In this prospective randomized-controlled trial, 50 patientswith stable angina and preserved myocardial function undergoingOPCAB were randomly assigned to receive either 0.5 mg kg^–1of ketamine (Ketamine group, n=25) or normal saline (Controlgroup, n=25) during induction of anaesthesia. Inflammatory markersincluding C-reactive protein (CRP), interleukin (IL)-6, tumournecrosis factor- (TNF-), and cardiac enzymes were measured previousto induction (T1), 4 h after surgery (T2), and the first andsecond days after the surgery (T3 and T4). Results: There were no significant intergroup differences in the serumconcentrations of the CRP, IL-6, and TNF- and cardiac enzymes.Pro-inflammatory markers and cardiac enzymes, except TNF-, wereall increased after the surgery compared with baseline valuesin both groups. Conclusions: Low-dose ketamine administered during anaesthesia inductiondid not exert any evident anti-inflammatory effect in termsof reducing the serum concentrations of pro-inflammatory markersin low-risk patients undergoing OPCAB.