Two years' experience with inspiration breath-hold in liver SBRT

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The workflow of inspiration breath-hold SBRT for liver metastases is described.

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Inspiration breath-hold in liver SBRT is feasible for 95% of the patients.

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An individual margin recipe for inspiration breath-hold liver SBRT is explained.

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Margin reduction of 10 mm using inspiration breath-hold compared to free breathing.

Adverse events and survival after closing- and opening-wedge high tibial osteotomy: a comparative study of 412 patients

PURPOSE

Varus medial knee osteoarthritis (OA) can be treated with a closing-wedge (CW) or opening-wedge (OW) high tibial osteotomy (HTO). Little is known about the adverse event (AE) rate of these techniques. The purpose of this study was to examine the AE rate and survival rate of a consecutive series of 412 patients undergoing CW- or OW-HTO.

METHODS

Medical records were retrospectively screened, and all patients who underwent HTO from 1993 to 2012 at the Erasmus University Medical Centre were assessed with a self-administered questionnaire. Patients filled in the intermittent and constant osteoarthritis pain score, knee injury and osteoarthritis outcome score, and a general questionnaire focusing on AE.

RESULTS

Medical records of 412 patients (354 CW- and 112 OW-HTOs) were screened. Of the 358 eligible patients, 291 (81 %) returned their questionnaire. A total of 80 AE (17 %) were found in 466 osteotomies. In the CW-group, 47 (13 %) serious adverse events (SAE) and 2 (0.6 %) AE were found. In the OW-group, 17 (15 %) SAE and 14 (13 %) AE were found. The most common AE was in 14 (4 %) patients of the CW-group sensory palsy of the common peroneal nerve. The most common AE in the OW-group was persistent pain at the iliac crest [11 (9.8 %) patients]. Hardware was removed in 48 % of the CW-osteotomies and 71 % of the OW-osteotomies (p < 0.05). The probability of survival was 75 % after 10 years in the CW-group versus 90 % in the OW-group (p < 0.05). In both groups, an equal number of patients were "in need for prosthesis" according to OARSI criteria.

CONCLUSION

OW-HTO was associated with more AE than CW-HTO. OW-HTO resulted in better survival than CW-HTO. However, in both groups an equal number of patients were in need for prosthesis.

LEVEL OF EVIDENCE

Retrospective comparative study, Level III.

Experimental neuropathy increases limbic forebrain CRF

Neuropathic pain is often accompanied by stress, anxiety and depression. Although there is evidence for involvement of corticotropin-releasing factor (CRF), the detailed neuronal basis of these pain-related mood alterations is unknown. This study shows that peripheral mononeuropathy was accompanied by changes in limbic forebrain CRF, but did not lead to changes in the functioning of the hypothalamo-pituitary-adrenal axis and the midbrain Edinger-Westphal centrally projecting (EWcp) neuron population, which play main roles in the organism's response to acute pain. Twenty-four days after chronic constriction injury (CCI) of the rat sciatic nerve, the oval bed nucleus of the stria terminalis (BSTov) contained substantially more Crf mRNA as did the central amygdala (CeA), which, in addition, possessed more CRF. In contrast, Crf mRNA and CRF contents of the hypothalamic paraventricular nucleus (PVN) were unaffected by CCI. Similarly, EWcp neurons, producing the CRF family member urocortin 1 (Ucn1) and constitutively activated by various stressors including acute pain, did not show an effect of CCI on Ucn1 mRNA or Ucn1. Also, the immediate early gene products cFos and deltaFosB in the EWcp were unaffected by CCI. These results indicate that neuropathic pain does not act via the HPA-axis or the EWcp, but includes a main role of Crf in the limbic system, which is in clear contrast to stressors like acute and chronic pain, which primarily act on the PVN and the EWcp.

The relation between skin temperature increase and sensory block height in spinal anaesthesia using infrared thermography

BACKGROUND AND OBJECTIVES

To evaluate the feasibility of determining the extent of sympathetic blockade by skin temperature measurement with infrared thermography and relate the cranial extent of the temperature increase to that of the sensory block after spinal anaesthesia.

METHODS

Before and 5, 10 and 20 min after the administration of spinal anaesthesia, skin temperatures were measured with infrared thermography at the dermatomes T2-L3, in 12 male patients scheduled for lower limb surgery. The most cephalad dermatome at which sensory blockade occurred was related to the dermatome at which the largest temperature jump (corrected for baseline temperature) occurred.

RESULTS

The baseline temperatures showed considerable variation across the dermatomes, being lower below T12 than at the thoracic dermatomes. The mean difference between the level of the cephalad skin temperature elevation front (mean 1.03 °C, SD 0.8 °C) and cranial sensory block height was 0.10 dermatomes (SD 1.16), correlation coefficient (0.88, P<0.001).

CONCLUSION

The varying baseline temperatures across the trunk, the limited sympathetic block-induced increase in skin temperature at the trunk and the difficult control of influences from the surroundings partly obscured the extent of the skin temperature increase and its correlation to sensory block height. These factors have to be controlled to improve the use of infrared cameras as an easy bedside tool for predicting the cranial extent of (sympathetic blockade during) spinal anaesthesia.

Verification measurements and clinical evaluation of the iPlan RT Monte Carlo dose algorithm for 6 MV photon energy

This study presents data for verification of the iPlan RT Monte Carlo (MC) dose algorithm (BrainLAB, Feldkirchen, Germany). MC calculations were compared with pencil beam (PB) calculations and verification measurements in phantoms with lung-equivalent material, air cavities or bone-equivalent material to mimic head and neck and thorax and in an Alderson anthropomorphic phantom. Dosimetric accuracy of MC for the micro-multileaf collimator (MLC) simulation was tested in a homogeneous phantom. All measurements were performed using an ionization chamber and Kodak EDR2 films with Novalis 6 MV photon beams. Dose distributions measured with film and calculated with MC in the homogeneous phantom are in excellent agreement for oval, C and squiggle-shaped fields and for a clinical IMRT plan. For a field with completely closed MLC, MC is much closer to the experimental result than the PB calculations. For fields larger than the dimensions of the inhomogeneities the MC calculations show excellent agreement (within 3%/1 mm) with the experimental data. MC calculations in the anthropomorphic phantom show good agreement with measurements for conformal beam plans and reasonable agreement for dynamic conformal arc and IMRT plans. For 6 head and neck and 15 lung patients a comparison of the MC plan with the PB plan was performed. Our results demonstrate that MC is able to accurately predict the dose in the presence of inhomogeneities typical for head and neck and thorax regions with reasonable calculation times (5-20 min). Lateral electron transport was well reproduced in MC calculations. We are planning to implement MC calculations for head and neck and lung cancer patients.

A new approach to anesthesia management in myasthenia gravis: reversal of neuromuscular blockade by sugammadex

A neuromuscular blocking drug (NMBD) induced neuromuscular blockade (NMB) in patients with myasthenia gravis usually dissipates either spontaneously or by administration of neostigmine. We administered sugammadex to a patient with myasthenia gravis to reverse a rocuronium-induced profound NMB. NMBDs predispose such patients to severe postoperative residual paralysis and respiratory complications. Sugammadex binds steroidal NMBDs and, therefore reverses a rocuronium or vecuronium-induced NMB, without interfering with cholinergic transmission. A rapid and complete recovery from profound NMB was achieved and no adverse events were observed. This case suggests that sugammadex is a safe and effective antagonist of a rocuronium induced NMB blockade in patients with myasthenia gravis.

A needle guidance device compared to free hand technique in an ultrasound-guided interventional task using a phantom

In this in vitro study, a needle guidance device and a 'free hand' technique for ultrasound guided needle insertion were compared in a simulated ultrasound-guided interventional task using a porcine phantom. Residents inexperienced in using ultrasonography were asked to insert a needle, using an in-plane techniques, and to make contact with metal rods at a depth of 2 and 4 cm in the phantom. The transducer made angles of 90 degrees, 60 degrees and 45 degrees with the surface of the phantom. The times to perform the procedures were significantly shorter and the needle visualisation was significantly better when using the needle guidance device. The residents ranked their satisfaction with the needle-guidance device significantly better than the 'free-hand' technique. This device may be beneficial when performing ultrasound guided peripheral nerve blocks, especially by inexperienced operators.

Time course of action of sugammadex (Org 25969) on rocuronium-induced block in the Rhesus monkey, using a simple model of equilibration of complex formation

BACKGROUND

Reversal of neuromuscular block can be accomplished by chemical encapsulation of rocuronium by sugammadex (Org 25969), a synthetic gamma-cyclodextrin derivative. The present study determined the time course of the reversal action of sugammadex on rocuronium-induced block in the anaesthetized Rhesus monkey using train-of-four stimulation.

METHODS

A bolus injection of rocuronium 100 microg kg(-1) (about 1xED(90)) was given to determine the degree of neuromuscular block reached by this dose. After complete spontaneous recovery, a rapid bolus injection of sugammadex, 1 mg kg(-1), was given and at different time intervals (15, 30 or 60 min, in three different experiments) the effect of another rocuronium bolus injection of 100 microg kg(-1) was determined.

RESULTS

Injection of the first dose of rocuronium resulted in a mean neuromuscular block (depression of first twitch) of 93 (SEM=1.6)%. Fifteen minutes after injection of sugammadex the same rocuronium dose resulted in 17% (SEM=5.6) block. After 30 and 60 min these maximum blocks amounted to 49% (SEM=7.6) and 79% (SEM=4.2), respectively. The estimated half-life of sugammadex in Rhesus monkey is 30 (SEM=4.9) min.

CONCLUSIONS

The half-life of sugammadex (Org 25969), a new fast and efficient reversal agent for rocuronium-induced block, is relatively short in the Rhesus monkey, implying the possibility to perform neuromuscular block by rocuronium shortly after reversal of a prior block. In translation to the human situation differences in rocuronium sensitivity and kinetics should be taken into account.

An effective correlation dimension and burst suppression ratio of the EEG in rat. Correlation with sevoflurane induced anaesthetic depth

BACKGROUND AND OBJECTIVE

Anaesthesiologists need parameters that measure the depth of anaesthesia. In the context of this need, the present study investigated in rats how two variables from the electroencephalogram, the burst suppression ratio and effective correlation dimension correlated with a measure of anaesthetic depth as measured in the strength of a noxious withdrawal reflex.

METHODS

Eight rats were exposed to different inspiratory concentrations of sevoflurane, each rat in two separate experiments. In the first experiment, spontaneously breathing animals could move freely and no painful stimuli were applied. In the second experiment, in mechanically ventilated restrained anaesthetized rats, the withdrawal reflex was measured every 80 s. In both experiments the electroencephalogram was continuously recorded. The concentration in the effector compartment was estimated using a first order two compartment model. Correlation dimension was computed following the Grassberger/Procaccia/Takens approach with optimized parameter settings to achieve maximum sensitivity to anaesthetic drug effects and enable real-time computation. The Hill, equation was fitted to the data, describing the effect as a function of sevoflurane concentration.

RESULTS

Good correlations of Depth of Anaesthesia with correlation dimension as well as burst suppression ratio were established in both types of experiments. Arousal by noxious stimuli decreased burst suppression ratio and increased correlation dimension. The effective sevoflurane concentration associated with 50% of the maximum effect (C50) was higher in experiment II (stimulation) than in experiment I (no stimulation): i.e. for correlation dimension 2.18% vs. 0.60% and for burst suppression ratio 3.07% vs. 1.73%. The slope factors were: gammaCD = 4.15 vs. gammaCD = 1.73 and gammaBSR = 5.2 vs. gammaBSR = 5.4. Correlation dimension and burst suppression ratio both correlated with the strength of the withdrawal reflex with correlation coefficients of 0.46 and 0.66 respectively (P < 0.001).

CONCLUSIONS

Both correlation dimension and burst suppression ratio are related to anaesthetic depth and are affected by noxious stimuli. The relationship between anaesthetic depth and burst suppression ratio is confirmed and the potential of correlation dimension is demonstrated.

Sugammadex, a new reversal agent for neuromuscular block induced by rocuronium in the anaesthetized Rhesus monkey †

BACKGROUND

Binding of the steroidal molecule of rocuronium by a cyclodextrin is a new concept for reversal of neuromuscular block. The present study evaluated the ability of Sugammadex Org 25969, a synthetic gamma-cyclodextrin derivative, to reverse constant neuromuscular block of about 90% induced by rocuronium or the non-steroidal neuromuscular blocking drugs, mivacurium or atracurium, in the anaesthetized Rhesus monkey.

METHODS

After a bolus injection of rocuronium, mivacurium or atracurium, a continuous infusion of these drugs was started to maintain the first twitch contraction of the train-of-four at approximately 10% of its baseline value. After a steady state block of at least 10 min the infusion was stopped and the preparation was allowed to recover spontaneously. This process was repeated, but at the time the infusion was stopped, either sugammadex 0.5 or 1.0 mg kg(-1) was given in the rocuronium-induced blockade and sugammadex 1.0 mg kg(-1) was given in the mivacurium- and atracurium-induced blockade.

RESULTS

Sugammadex caused a rapid and complete reversal of rocuronium-induced neuromuscular block. The recovery time to train of four ratio=0.9 after spontaneous recovery was 14.4 min (sd=3.4 min; n=14). This was reduced significantly (P<0.001) to 3.7 min (sd=3.3 min; n=4) with sugammadex 0.5 mg kg(-1) and to 1.9 min (sd=1.0 min; n=4) with sugammadex 1.0 mg kg(-1). Signs of residual blockade or re-curarization were not observed. Reversal of mivacurium- or atracurium-induced neuromuscular block (n=2 in each experiment) by sugammadex (1.0 mg kg(-1)) was not effective. In all experiments, injection of sugammadex had no effects on blood pressure or heart rate.

CONCLUSIONS

Sugammadex is effective in reversing rocuronium, but not mivacurium- or atracurium-induced neuromuscular block.

Chemical encapsulation of rocuronium by synthetic cyclodextrin derivatives: reversal of neuromuscular block in anaesthetized Rhesus monkeys †

BACKGROUND

At present, reversal of neuromuscular block induced by steroidal neuromuscular blocking agents (NMBAs) is achieved by administration of cholinesterase inhibitors. Chemical encapsulation of steroidal NMBAs, such as rocuronium, by a cyclodextrin is a new concept in neuromuscular block reversal. The present study evaluates the capacity of nine synthetic cyclodextrin derivatives (Org 25288, Org 25289, Org 25467, Org 25168, Org 25169, Org 25555, Org 25166, Org 26142, and Org 25969) to reverse constant neuromuscular block of approximately 90%, induced by rocuronium infusion in the Rhesus monkey, using single twitch stimulation. The ability of these cyclodextrin derivatives to reverse neuromuscular block was compared with the reversal of the same neuromuscular block by the commonly used combination of neostigmine and atropine.

METHODS

After a bolus injection of rocuronium, continuous infusion was started to reduce twitch contractions to approximately 10% of baseline values. After a steady state block of at least 10 min the infusion was stopped and the preparation was allowed to recover spontaneously. This process was repeated, but at the time the infusion was stopped, either one of the nine cyclodextrin derivatives or a combination of neostigmine and atropine was given.

RESULTS

Recovery with cyclodextrin derivatives Org 26142 and Org 25969 was faster than after a combination of neostigmine and atropine (P<0.05). Injection of these cyclodextrin derivatives did not affect blood pressure or heart rate. Signs of residual block or recurarization were not observed in any of these experiments. In the experiments in which a combination of neostigmine and atropine was given, two animals showed signs of abdominal discomfort as frequently seen after the administration of neostigmine and significant changes in circulatory variables.

CONCLUSIONS

Chemical encapsulation or chelation of rocuronium is a new concept in reversing neuromuscular block induced by rocuronium.

Do diagnostic segmental nerve root blocks in chronic low back pain patients with radiation to the leg lack distinct sensory effects? A preliminary study

BACKGROUND

The present preliminary study documents the effects of a selective nerve root block (SNB) with short or long acting local anaesthetic compared with baseline measurements in patients with chronic low back pain radiating to the leg with maximum pain in one dermatome (L4).

METHODS

Ten consecutive patients underwent 20 controlled SNBs at L4 with ropivacaine 0.25% and lidocaine 1% in a prospective, randomized, double blind, crossover fashion. Baseline measurements included sensory function (assessed by pinprick on both unaffected and painful leg) and pain (Verbal Numeric Rating Scale; VNRS, 0-10). A change in size of areas with altered sensory function >10% and a VNRS change of 2 points were considered clinically significant. P-values<0.05 were considered statistically significant.

RESULTS

Asymptomatic hypoaesthesia, variable in extent and non-dermatomal in distribution, was present in seven patients at baseline. It appeared to be more extensive and distal with longer duration of pre-existing pain. SNB produced no consistent changes in extent and distribution of hypoaesthetic areas. Change in VNRS did not correlate with the extent of pre-block or post-block hypoaesthesia. No differences in effects were found between lidocaine and ropivacaine.

CONCLUSIONS

Pre-block assessment of sensory function is essential to assess the net effect of SNBs. In this small study group, SNBs failed to demonstrate uniform or distinct effects on sensory function.

Depth of the thoracic epidural space in children

Thoracic epidural anaesthesia in anaesthetized children requires a meticulous technique and may have an increased success rate when the distance between skin and epidural space is known. The objective of this observational study was to measure the skin to epidural distance (SED) during thoracic epidural puncture in 61 children. The epidural puncture was performed using the loss of resistance technique with saline 0.9%. The distance from the needle tip to the point where the needle emerged from the skin was measured. The post-operative analgesia parameters were also measured. Skin to epidural distance correlated significantly with the age and weight of the children. The equation for the relation between SED (cm) and age was 2.15 + (0.01 x months) and for SED vs weight was 1.95 + (0.045 x kg). Despite considerable variability among individuals, the observed correlation of SED with both age and weight shows that this parameter may be helpful to guide thoracic epidural puncture in anaesthetized children.

Electromyographic assessment of blink and corneal reflexes during midazolam administration: useful methods for assessing depth of anesthesia?

BACKGROUND

There are at least three components of the anesthetic state: loss of consciousness, amnesia and obtundation of reflex responses to noxious stimuli. To investigate the third component, we used a standard electrical stimulus to evoke a blink reflex, which was electromyographically recorded. These data may give information on the anesthetic state.

METHODS

The relation between the electrically evoked blink and corneal reflexes and the depth of sedation and anesthesia induced with intravenous midazolam was investigated. Ten patients received i.v. increments of midazolam (1 mg, 2 mg, 3 mg, 3 mg, 3 mg, etc., until a 21-mg total dose) to create a step-wise deepening of sedation and anesthesia. Depth of anesthesia was assessed by the Observer's Assessment of Alertness/Sedation (OAAS) scale, ranging from 5 ( = awake and alert) to 0 ( = no motor response to tetanic stimulation).

RESULTS

Latency of the first (R1) and second (R2) blink components and the corneal (C) reflex component increased, whereas duration and area decreased with increasing depth of sedation and anesthesia. R1 was last seen at an OAAS score [mean (SD)] of 1.8 (0.8), R2 at a score of 3.1 (1.1), C at a score of 3.8 (0.8), and R3 at 4.8 (0.5). These end-points were all statistically different from each other, except R2 vs. C.

CONCLUSIONS

Our results suggest that the differential sensitivity of the components of the blink reflex could be useful to monitor depth of sedation and light levels of anesthesia during the administration of midazolam.

A blind spot for secondary gain affecting therapy outcomes

BACKGROUND

A study to determine whether the expectation for secondary gain held by psychiatric outpatients was associated with therapy outcomes.

METHODS

The study was conducted at a Dutch psychiatric outpatient department. Our investigation set out to explore the expectation of obtaining secondary gain by directly asking the patient and clinician via questionnaires whether the patient anticipated to get specific "benefits" from being in therapy.

RESULTS

From 166 patients, 70 (42.2%) reported to expect secondary gain while in therapy. We found a significant relation between expectation for secondary gain and treatment outcomes. Patients with expectations for secondary gain were significantly more prone to poor therapy outcome. Only in nine of 147 cases (6%) did patients explicitly express their expectations for secondary gain towards a psychiatrist. Moreover, expectations for secondary gain did not appear to be related to Axis I and Axis II diagnoses.

DISCUSSION

Secondary gain appeared to be a "veiled motive" for getting therapy: patients did not express their expectations for secondary gain explicitly towards a psychiatrist. This aspect of veiled motives is of particular relevance in regard to the fact that expectations for secondary gain appeared to affect therapy results.

Non-depolarizing neuromuscular blocking activity of bisquaternary amino di- and tripeptide derivatives

Herein we describe the synthesis of novel di- and tripeptide derivatives with two quaternary nitrogen groups attached and the biological testing of these compounds for neuromuscular blocking (NMB) activity in vitro and in vivo. The short peptide scaffold was selected because it offers potential for desired distance between the two pharmacophoric quaternary nitrogen groups, short duration of action, straightforward synthesis, and compatibility with an injectable formulation. From a small series of compounds 20c,e are identified as effective non-depolarizing NMB agents in vitro and in vivo in anesthetized cats and Rhesus monkeys with potencies similar to those of the clinical reference compounds rocuronium (4) and suxamethonium (2) (monkey ED(90) = 0.68, 0.23, 0.16, 5.04 micromol/kg, respectively). These new peptide derivatives 20c,e have similar potency and onset time but longer duration and slower recovery than the clinically used reference compounds. The structure-activity relationships described for this chemical series lead to the conclusion that the di- or tripeptide fragment can be regarded as an alternative template to the steroid or aliphatic ester of previously reported NMBs and within this tripeptide-derived series clog P correlates well with in vitro NMB activity.

The influence of diazepam on the electroencephalogram-evoked potential interrelation in rats

Though being a sedative, diazepam increases beta-activity in the electroencephalogram (EEG). Diazepam also affects auditory evoked potentials (AEPs). We investigated if the effect of diazepam on AEPs could be ascribed to its beta-increasing effect. Eight rats received vehicle and diazepam counterbalanced. AEPs were ranked in ten categories according to the percentages of beta-activity in the pre-stimulus electroencephalogram (EEG). With vehicle, the P(29), N(51) and P(67) AEP components increased and cross-correlation coefficients (CCCs) declined with increasing beta-activity. With diazepam AEP components and CCCs remained unchanged. All AEPs with diazepam closely resembled the AEP of the lowest beta-category obtained with vehicle. We conclude that the effect of diazepam on AEPs can not be ascribed to its beta-enhancing effect. Diazepam disrupts the normal AEP-EEG relation such that diazepam-effects on AEPs seem to reflect the sedative effects of diazepam and not its beta-increasing effects.

Correlation dimension of the human electroencephalogram corresponds with cognitive load

This study aimed at assessing the effects of cognitive activity and mental task load on the correlation dimension of the human electroencephalogram (EEG). Three experimental conditions were created: a baseline condition and two cognitive task conditions, a calculation task and a time estimation task. The calculation task was supposed to induce a higher mental load than the time estimation task, which is regarded as a less complex one. This was verified by a subjective rating scale. All conditions differed significantly in subjective estimated task load. The correlation dimension appeared to be higher in both task conditions compared to the baseline condition. A comparison of the two tasks indicated that the difference in correlation dimension between calculation and time estimation was also significant, with the highest value for calculation. It is concluded that cognitive and mental activity is associated with a higher correlation dimension in the EEG. This implies that the correlation dimension is a sensitive parameter in the analysis of electrical brain activity.

Elevated detection thresholds for mechanical stimuli in chronic pain patients: support for a central mechanism

OBJECTIVE

To investigate the relation between pain provoking cervical segments identified by diagnostic dorsal root blockades and elevation of detection thresholds in patients suffering from chronic cervicobrachialgia (CCB).

DESIGN

Quantitative sensory testing (light touch) of the cervical dermatomes using Semmes-Weinstein monofilaments.

SETTING

A university pain clinic.

SUBJECTS

Thirty-nine patients with CCB, with no clinical or diagnostic evidence of radiculopathy or surgically treatable bony lesion and with one main pain-provoking cervical segment identified by diagnostic dorsal root blockades.

OUTCOME MEASURES

Detection thresholds with 95% confidence intervals (95% CI) of pain-provoking segments, compared with surrounding and contralateral segments and with normal values for cervical dermatomes.

RESULTS

Patients' detection thresholds were significantly (p < .001) higher than those for normal subjects: 3.51 (95% CI, 2.71-4.31) and 3.10 (95% CI, 2.34-3.86), respectively. No significant differences existed between the segments. The elevations were systematic. However, thresholds on the painful side were consistently, slightly higher than those on the contralateral side.

CONCLUSION

Supporting earlier studies, results from CCB patients in the present study showed systematic elevation of detection thresholds (low threshold mechanoreceptors), an adaptation in contrast with, but not contradictory to, central sensitization of high threshold neurons in chronic pain.

Contractures in skeletal muscle of malignant hyperthermia susceptible patients after in vitro exposure to sevoflurane

BACKGROUND

Sevoflurane, a potent inhalational anaesthetic agent that is structurally similar to halothane, has some favourable characteristics, but may also be able to trigger malignant hyperthermia (MH) in susceptible patients. The diagnosis of malignant hyperthermia susceptibility relies on the in vitro contracture test on skeletal muscle. The present study was undertaken to investigate whether exposure to sevoflurane of muscles of malignant hyperthermia susceptible (MHS) patients would also cause an abnormal contracture.

METHODS

Muscle fascicles obtained from three MHS patients, one malignant hyperthermia non-susceptible (MHN) patient, two control patients and one malignant hyperthermia equivocal (MHE) patient were exposed to sevoflurane instead of halothane in the in vitro contracture test, carried out according to the protocol of the European Malignant Hyperthermia Group. The muscle fascicles were surplus to diagnostic requirements. Sevoflurane concentrations in the testbath were measured using a headspace gas chromatographic technique.

RESULTS

The kinetics of sevoflurane concentration in the testbath were similar to those of halothane. An in vitro contracture response of 2 mN or more was seen in all four MHS/MHE patients with sevoflurane but not in the three control/MHN patients. The magnitude of muscle contracture in the sevoflurane test was less than in the conventional halothane test at comparable testbath concentrations.

CONCLUSIONS

Sevoflurane can trigger an abnormal contracture in human muscle in vitro. This is indicative of malignant hyperthermia susceptibility. Exposure to sevoflurane should be avoided in patients thought to be susceptible to malignant hyperthermia.

Evaluation of the electroencephalographic bispectral index during fentanyl-midazolam anaesthesia for cardiac surgery. Does it predict haemodynamic responses during endotracheal intubation and sternotomy?

The bispectral index, a value derived from the electroencephalogram, has been proposed as a measure of anaesthetic effect. The aim of the present study was to evaluate the bispectral index during midazolam-fentanyl anaesthesia for cardiac surgery for its possible role as a predictor of increases in systolic blood pressure during endotracheal intubation and sternotomy. After institutional approval 15 consenting patients, scheduled for elective cardiac surgery, were selected for the study. Anaesthesia was induced in all patients with a loading dose of fentanyl 7.5-10 micrograms kg-1, midazolam 0.15 mg kg-1 and pancuronium 0.1 mg kg-1. After a further bolus dose of fentanyl 10-12.5 micrograms kg-1 prior to the start of incision and sternotomy, maintenance infusion rates of fentanyl 4-6 micrograms kg-1 h-1 and midazolam 0.1 mg kg-1 h-1 were started and continued through surgery at the discretion of the anaesthetist and guided by the presenting clinical and haemodynamic responses. The control of anaesthesia was never based on the value of the bispectral index. The mean bispectral index value decreased from 95.7 (3.1) at base-line to 59.5 (12.0) after induction of anaesthesia and then remained below 70 throughout surgery. However, there was an important interindividual variability in bispectral index values despite standardized dosages of fentanyl and midazolam. There was no significant correlation between the bispectral index values in the pre-intubation and pre-incision period and the changes in systolic blood pressure during endotracheal intubation and sternotomy, respectively. In conclusion, the large intersubject variability in the bispectral index values should be investigated further in the light of the great variability in the clinical effects of midazolam and fentanyl. The lack of significant correlation between the bispectral index values and the haemodynamic responses suggest that the bispectral index, which is a helpful monitor of anaesthetic depth, is not a very reliable monitor of global anaesthetic adequacy during total intravenous anaesthesia with a combination of midazolam and fentanyl in cardiac surgical patients.

Intrathecal coadministration of bupivacaine diminishes morphine dose progression during long-term intrathecal infusion in cancer patients

OBJECTIVE

To determine the difference in intrathecal morphine dose progression between a continuous intrathecal infusion of a morphine/bupivacaine mixture and morphine for pain relief in patients with cancer.

DESIGN

Patients were treated with intrathecal drugs in a randomized study and followed prospectively until death.

SETTING

Institute for Anesthesiology, Department of Pain Treatment, University Hospital Nijmegen, St Radboud, The Netherlands.

PATIENTS

Twenty patients with cancer were selected for intrathecal treatment because of either side effects or inadequate relief during conventional pain treatment.

INTERVENTIONS

Intrathecal drug infusion rates and medication were adjusted according to pain relief and side effects.

OUTCOME MEASURES

Progression of intrathecal morphine dose during a phase of adequate analgesia in both groups following regression analysis and analysis of possible treatment related side effects.

RESULTS

The combination of intrathecal morphine and bupivacaine resulted in a diminished progression of the intrathecal morphine dose (slope of regression line = 0.0003 vs. 0.005, p = 0.0001) during a phase of stable analgesia in comparison with the morphine group. No serious side effects presented.

CONCLUSION

The diminished intrathecal morphine dose increase in the combination group is considered to be due to a synergistic effect of bupivacaine on the intrathecal morphine-induced antinociception. A dose increment during long-term intrathecal infusion in cancer patients appears to be related to both disease progression and tolerance phenomena.

Effects of polytherapy compared with monotherapy in antiepileptic drugs: an animal study

Although monotherapy in epilepsy treatment is frequently advocated, this is not based on studies with equal drug loads. This study was performed to investigate the experimental background of polytherapy with standardized drug loads. Dose-dependent effects on grip strength, accelerod performance, and spontaneous behavior of rats was used to study the effect of combining valproate and ethosuximide. The potency of the drugs (combination) was obtained by fitting the sigmoid Emax equation to the data. Drug interaction was assessed using the isobologram method and quantified by comparing equivalent drug loads with their 95% confidence intervals. We found that the effects of valproate and ethosuximide combine in a simple additive way in the grip strength experiment as well as in the accelerod experiment. In the behavioral studies, however, a higher drug load of the combination was needed to obtain the same amount of sedation, signifying infra-additivity. Infra-additivity of sedative effects is an important finding because this is by far the most frequent side effect mentioned in human studies. However, assessment of the therapeutic effect of the combination will have to be completed before a preference for mono- or polytherapy, based on the balance of adverse effects and efficacy, can be expressed.

Normal values for sensory thresholds in the cervical dermatomes: a critical note on the use of Semmes-Weinstein monofilaments

In many healthy subjects, sensory thresholds for touch using Semmes-Weinstein monofilaments appear to be higher than the 2.83 filament, which some authors have suggested as a screening instrument. The currently proposed normal values, the interpretation of results, as well as the calibration of the filaments are questioned. A normative study of 20 normal subjects using Semmes-Weinstein monofilaments was undertaken at a pain clinic in a university hospital. The main outcome measures were sensory thresholds (touch) in dermatomes C3 to C8. Per subject, 24 sites were tested and 50 sites in dermatome C5 left of one subject. The threshold distribution patterns were analyzed. The mean threshold expressed in log (10 x F; with F = force in milligrams) of all sites (n = 480) in normal subjects was 3.10 (95% confidence interval, 2.34-3.86). The mean threshold per subject was 3.10 (range, 2.70-3.50). The mean threshold of 50 sites in dermatome C5 left of one healthy subject was 3.22 (range, 2.42-4.02). In the study contained herein, sensory thresholds in the cervical dermatomes have been shown to be higher than the generally proposed normal values. The cervical dermatomes show thresholds from 0.13 to 8.47 mN. This concurs with other authors. Results depend on the testing method, which in this study was different from previous studies. The testing method must be described accurately. The distribution of thresholds within all tested sites, dermatomes, subjects, or even within one dermatome in one subject are comparable. Individual results have to be related to the mean of the subject to determine abnormality. Calibration of the monofilaments is important. When these terms are met, testing with Semmes-Weinstein monofilaments is an easy, reliable, and relatively inexpensive method of quantitative sensory testing and can be a useful tool in the process of rehabilitation.

Extension of sensory blockade after thoracic epidural administration of a test dose of lidocaine at three different levels

To evaluate the relationship between the level of thoracic epidural injection and the extension of sensory blockade, we inserted radiopaque epidural catheters in 87 patients at the high (C7-T2, n = 28), mid (T3-5, n = 29) or low (T7-9, n = 30) thoracic levels. Fifteen minutes after the epidural administration of 60 mg of lidocaine, the mean (+/- SD) sensory block extension varied from 5.4 +/- 3.1 to 7.7 +/- 1.8 segments. The level of epidural puncture was a statistically significant factor in determining the cranial and caudal borders of sensory blockade (P = 0.0001, analysis of variance), but in determining for the total number of segments blocked. The number of blocked dermatomes located cranially of the puncture level increased significantly with descending injection site (P = 0.0001). We acquired chest radiographs in 61 patients to determine epidural catheter tip position. Direction of the epidural catheter tip was not a significant factor in determining the extension or borders of sensory blockade. We conclude that the extension of sensory blockade in thoracic epidural anesthesia is not influenced by the level of epidural puncture or catheter tip direction. There is, however, a more cranial spread of sensory blockade in the low thoracic region compared with the high thoracic region.

IMPLICATIONS

After evaluating the extension and pattern of sensory blockade in high, mid, and low thoracic epidural analgesia, the authors suggest that it is safe to use similar dosage regimens in all three regions, and that in high thoracic epidural analgesia, it is important to insert the epidural catheter at the level of the intended cranial border of blockade.

Responses to propofol in relation to GABA functionality of discrete parts of the brain of rats

Genetically-determined regional differences in the GABA-ergic make-up of the brain exist in two lines of Wistar rats viz apomorphine-susceptible (APO-SUS) and apomorphine-unsusceptible (APO-UNSUS) Wistar rats, Propofol is a GABA-mimetic general anesthetic. This study compared the responses to propofol in APO-SUS and APO-UNSUS rats. Propofol induced a higher incidence of involuntary muscular contractions and oral movements, but a lower incidence of grooming, in APO-SUS rats than in APO-UNSUS rats. Reflex inhibition and narcosis, being defined as the behavior marked by both full absence of purposeful movements and by complete loss of righting reflexes, after propofol did not differ between the two lines. APO-SUS rats had less variation of the heart rates and greater variations of diastolic arterial pressures in response to electrical stimulation than the APO-UNSUS rats, and these variations were reduced by increasing doses of propofol. Arterial pressures in APO-SUS rats were higher than in APO-UNSUS rats. Propofol caused a biphasic change in intra-arterial pressures and had the greatest effect in APO-SUS rats. Differences in cerebral GABA transmission, especially in the striato-nigro-collicular pathway, did not give rise to differences in the effect of propofol on narcosis and hindlimb withdrawal reflex. In contrast, these differences in GABA transmission were accompanied by line-specific differences in effect of propofol on certain behavioral and cardiovascular parameters.

Monitoring during cryosurgery of bone tumors

BACKGROUND

Cryosurgery is used in orthopaedic oncology as adjuvant treatment after intralesional excision of bone tumors to induce cell death at and beyond the surgical margin. Monitoring freeze/thaw cycles during cryosurgery is beneficial in controlling a cryosurgical procedure and in preventing an unwarranted local extent of the freeze.

METHOD

We conducted a study of 15 cryosurgical procedures with the use of a protocolized temperature measuring system wit peroperative graphic visualization.

RESULTS

Using a liquid nitrogen spray, intralesional temperatures of -150 degrees C were achieved, which are, according to the literature, associated with cell death. Extralesional temperature measurements showed no sub-zero temperatures of surrounding important tissues.

CONCLUSIONS

Temperature recordings in and outside the lesion during cryosurgery in orthopaedic oncology are of importance to monitor the freeze/thaw cycles and are helpful in facilitating an effective cryosurgical procedure and in controlling the extent of the freeze, avoiding local complications.

Evaluation of thoracic epidural catheter position and migration using radio-opaque catheters

Migration of thoracic epidural radio-opaque catheters was evaluated in 25 patients scheduled for thoracic surgery in the supine position (n = 5) or in the lateral position with lateral extension of the thoracic spine (n = 20). Chest radiography was performed daily for 3 days after operation. Eighty-nine per cent of catheter tips were visualised in the epidural space. The catheter tip position was unchanged in all patients operated upon in the supine position. In the group operated upon in the lateral position, the catheter tip retracted from day 1 to day 2 by an average of 0.69 cm (SD 1.08; p < 0.05); from day 2 to day 3 the average retraction was 0.35 cm (SD 0.67; p < 0.05).

Intravenous regional anesthesia with 0.5% articaine, 0.5% lidocaine, or 0.5% prilocaine. A double-blind randomized clinical study

BACKGROUND AND OBJECTIVES

The purpose of this study was to compare the effectiveness of three local anesthetic agents for intravenous regional anesthesia in the upper limb. Side effects and plasma concentrations of the drugs in the doses administered for IVRA were also studied.

METHODS

Thirty patients in ASA groups I and II received intravenous regional anesthesia for surgery of the upper limb. In a double-blind prospective study, they were randomly allocated to receive one of three local anesthetics: articaine, lidocaine, or prilocaine. Patients received 40 mL of a 0.5% solution of the local anesthetic. The onset time of sensory block was assessed by pinprick and the extent of motor block was was scored as 0-3. Plasma concentrations of local anesthetics were determined in all patients from serial arterial blood samples drawn at predetermined times before and after tourniquet release.

RESULTS

The onset time of sensory block was significantly shorter (2.5 minutes) in the articaine group than in the lidocaine group (11.1 minutes) or the prilocaine group (10.9 minutes) (Scheffe, P < .05). Development of motor block was equal in all three groups (score 2). Estimation of plasma concentrations by high performance liquid chromatography showed that the peak level in all 30 patients was reached immediately after release of the tourniquet; plasma concentrations thereafter gradually declined. Maximum concentrations of articaine, lidocaine, and prilocaine were, 1.85, 8.5, and 4.4 micrograms/mL, respectively. No signs of local anesthetic toxicity of the cardiovascular or central nervous systems were seen.

CONCLUSION

Articaine had the fastest onset of sensory block and the lowest peak plasma concentration of the three local anesthetics when used for intravenous regional anesthesia.

Effect of isoflurane and sevoflurane on the magnitude and time course of neuromuscular block produced by vecuronium, pancuronium and atracurium

We have compared the ability of equipotent concentrations of isoflurane and sevoflurane to enhance the effect of non-depolarizing neuromuscular blocking drugs. Ninety ASA I and II patients of both sexes, aged 18-50 yr, were stratified into three blocker groups (Vec, Pan and Atr), to undergo neuromuscular block with vecuronium (n = 30), pancuronium (n = 30) or atracurium (n = 30), respectively. Within each group, patients were allocated randomly to one of three anaesthetic subgroups to undergo maintenance of anaesthesia with: (1) alfentanil-nitrous oxide-oxygen (n = 10); (2) alfentanil-nitrous oxide-oxygen-isoflurane (n = 10); or (3) alfentanil-nitrous oxide-oxygen-sevoflurane (n = 10) anaesthesia. During maintenance of anaesthesia, end-tidal concentrations of isoflurane, sevoflurane and nitrous oxide were 0.95, 1.70 and 70%, respectively. Both the evoked integrated electromyogram and mechanomyogram of the adductor pollicis brevis muscle were measured simultaneously. In the Vec and Pan groups, a total dose of 40 micrograms kg-1 of vecuronium or pancuronium, respectively, was given, and in the Atr group a total dose of atracurium 100 micrograms kg-1. Each blocker was given in four equal doses and administered cumulatively. We showed that 0.95% isoflurane and 1.70% sevoflurane (corresponding to 0.8 MAC of each inhalation anaesthetic, omitting the MAC contribution of nitrous oxide) augmented and prolonged the neuromuscular block produced by vecuronium, pancuronium and atracurium to a similar degree.

Rocuronium with alfentanil and propofol allows intubation within 45 seconds

Following induction with alfentanil (20 micrograms kg-1) and propofol (2.0-2.5 mg kg-1), four groups of patients were given rocuronium to determine conditions for rapid sequence intubation. Two groups received 0.9 mg kg-1 and two groups received 0.6 mg kg-1. In one of each dose groups, intubation was attempted after 45 s and in the other after 60 s. Intubating conditions were scored on a four point scale but all were rated as excellent or good. Almost all intubating conditions were excellent in the 0.9 mg kg-1 groups.

Asymmetric fundus flavimaculatus/Stargardt's disease, associated with unilateral myopia

An unusual asymmetric pattern of fundus flavimaculatus was observed in a unilateral myopic patient. Although electrophysiologic testing was similar for both eyes, fundus lesions were different and less pronounced in the myopic eye.

High thoracic epidural sufentanil with bupivacaine: continuous infusion of high volume versus low volume

The purpose of the study was to investigate whether continuous infusion of a high volume of a sufentanil/bupivacaine mixture at a high thoracic level improves the analgesic effect of the mixture, compared with a dose-equivalent continuous low-volume infusion. In a prospective, observer-blind study, 60 patients scheduled for thoracic surgery received a thoracic epidural catheter for 3 days. The patients were randomly assigned by lot to one of two groups: a low-volume (LV) group (bupivacaine 0.75% with sufentanil 4 micrograms/mL, 1.0-1.3 mL/h), or a high-volume (HV) group (bupivacaine 0.125% with sufentanil 0.7 microgram/mL, 6-8 mL/h). On the first postoperative day significantly more patients in the LV group needed one or more epidural bolus injections because they experienced pain at rest (P < 0.05). On the second and third postoperative days there were no differences in bolus injections. Significantly more patients in the HV group did not require an extra epidural bolus injection (P < 0.05). There were no differences in the number of patients experiencing pain at exercise or in the incidence of side effects. A difference was found between both groups in the mean preoperative PaCO2 value (P < 0.05) and also for the PaCO2 values on Day 1 versus the preoperative values within the group (P < 0.05). On the first postoperative day the analgesic effects of a sufentanil/bupivacaine mixture at a high thoracic epidural level can be improved when injected at a continuous high-volume rate compared with a dose-equivalent continuous low-volume rate. This is true for pain at rest; for pain at exercise, there were no differences.

Irradiation and responsiveness to pain stimuli in rats

This study evaluates whether irradiation inhibits responses to pain in an animal model. We found that irradiation with doses of 10 Gy, 15 Gy and 17.5 Gy of the lumbar enlargement of the spinal cord inhibits the behavioural responses to the stimulus of the hot-plate. These doses were otherwise without effects. This data is discussed in view of the effects of irradiation of living cells, and we propose that a modification of pain signal processing is accomplished. Similar considerations apply to the human condition.

Accuracy and reproducibility of 30 devices for self-measurement of arterial blood pressure

Thirty commercially available noninvasive devices for self-measurement of blood pressure were tested for accuracy and reproducibility against intraarterial measurement in 15 normotensive and 15 hypertensive subjects. For reference to outpatient measurements, a standard sphygmomanometer was included. Analysis of the data for any device was performed according to a statistical model in which two types of errors, representing accuracy and reproducibility, were distinguished: offset (mean difference between intraarterial measurement and device) and standard deviation (comprising intraindividual and interindividual variability). Linearity of the devices was analyzed by linear regression with intraarterial measurement as independent variable. The average offset of all tested devices amounted to 11.7 mm Hg (ranging from -0.2 to 21.4 between instruments) for systolic blood pressure and -1.6 mm Hg (range -11.4 to 8.1) for diastolic blood pressure. The standard deviation between instruments ranged from 7.0 to 15.4 mm Hg for systolic and from 3.3 to 16.0 mm Hg for diastolic blood pressure. Except for the devices based on the oscillometric principle, most (semi-) automated devices demonstrated a variability similar to the mercury sphygmomanometer (offset = 14.3 for systolic and 0.1 mm Hg for diastolic pressure; standard deviation = 7.5 for systolic and 5.6 mm Hg for diastolic blood pressure). Devices based on the oscillometric principle had a significantly larger variability. It is concluded that new devices should be tested for accuracy and reproducibility before application for clinical use. Blood pressure measurements from instruments with larger offset are only comparable to values from other instruments after rescaling in accordance with their offset.

Interaction of antibiotics on pipecuronium-induced neuromuscular blockade

STUDY OBJECTIVE

To measure the interaction of two antibiotics (clindamycin and colistin) on neuromuscular blockade induced by pipecuronium bromide (a new long-acting, steroidal, nondepolarizing neuromuscular blocking drug).

DESIGN

Prospective, randomized, placebo-controlled study.

SETTING

Inpatient gynecologic and gastroenterologic service at a university medical center.

PATIENTS

Three groups of 20 ASA physical status I and II patients with normal kidney and liver function, taking no medication, and undergoing elective surgery under general anesthesia.

INTERVENTIONS

Anesthesia was induced with propofol and alfentanil intravenously (IV) and maintained with a propofol infusion and 60% nitrous oxide in oxygen. Pipecuronium bromide 50 micrograms/kg was administered after reaching a stable baseline of single-twitch response. At 25% recovery of pipecuronium-induced neuromuscular blockade, patients received one of two antibiotics, clindamycin 300 mg or colistin 1 million IU, or a placebo.

MEASUREMENTS AND MAIN RESULTS

The recovery index (RI, defined as time from 25% to 75% recovery of neuromuscular blockade) was measured using the single-twitch response of the adductor pollicis muscle with supramaximal stimulation of the ulnar nerve at the wrist. RI after administration of an antibiotic (given at 25% recovery) was measured and compared with RI of the control group using Student's unpaired t-test. Statistical analyses of the results showed a significant prolongation of the recovery time (from 25% to 75% recovery) of 40 minutes for colistin.

CONCLUSIONS

When this type of antibiotic is used during anesthesia with pipercuronium as a muscle relaxant, one must be aware of a significant prolongation of an already long-acting neuromuscular blockade and (although not observed in this study) possible problems in antagonism.

Effects of acupuncture and transcutaneous stimulation analgesia on plasma hormone levels during and after major abdominal surgery

The effects of acupuncture and transcutaneous electrical stimulation (TES) on plasma adrenaline (A) and noradrenaline (NA), adrenocorticotropic hormone (ACTH), beta-endorphin (beta E), anti-diuretic hormone (ADH) and hydrocortisone (cortisol) were evaluated during and, for four days after surgery in 42 male patients submitted to a standardized major abdominal operation in a comparative study of three different anaesthetic techniques. Group 1 received acupuncture and transcutaneous stimulation as the main non-pharmacological analgesic during surgery. Group 2 received moderate-dose fentanyl (initial bolus of 10 micrograms kg-1 followed by continuous infusion of 5 micrograms kg-1 h-1 for the first hour, and then 4 micrograms kg-1 h-1. Group 3 received a combination of both methods. In all three groups analgesia was supplemented, if necessary, by small bolus injections of 50 micrograms fentanyl. Anaesthesia was induced in all groups with thiopentone 5 mg kg-1 and vecuronium 0.1 mg kg-1 and patients were ventilated (N2O:O2 = 2:1) to achieve normocapnia without the use of a halogenated agent. Pre-operatively acupuncture plus TES in Groups 1 and 3 led to a rise in beta E (P < 0.05) without changes of haemodynamics. After intubation beta E did not increase further. Intubation in Group 2 led to an increase of beta E (P < 0.05) also, and to a rise in pulse rate and blood pressure (P < 0.05) in all three groups. Per-operatively acupuncture plus TES in Group 1 showed a response of circulating NA and cortisol similar to that in Groups 2 and 3, whereas the responses of the circulating A, ACTH, beta E and ADH in Group 1 were more pronounced (P < 0.01). Post-operatively no differences in the hormonal profiles could be discerned between the groups with or without acupuncture plus TES (Group 2 vs. Group 3) nor between those with or without moderate-dose fentanyl anaesthesia (Group 1 vs. Group 3). It is concluded that acupuncture and TES have no effect on the cardiovascular response to laryngoscopy and intubation. They can replace moderate-dose fentanyl anaesthesia in major abdominal surgery at the cost of a more enhanced per-operative neuroendocrine stress response, which does not, however, influence the postoperative hormonal profiles nor the rapidity of return to pre-operative values.

Natural history and visual outcome in patients with APMPPE

We undertook a retrospective study of the files of 21 patients (42 affected eyes) with acute posterior multifocal placoid pigment epitheliopathy to obtain details on the natural history of the disease and on the functional and visual outcome (mean follow up: 17 months). The final visual acuities were 8/10 or better in 34 eyes (81.0%), 7/10 to 2/10 in 6 eyes (14.2%) and 1/10 in two eyes (4.8%). Although the final visual acuity was good in most eyes, 24 eyes (57.2%) were still symptomatic due to scotomas (33.3%), metamorphosia (21.4%), decreased vision (16.6%), floaters (4.8%) and chronic redness (2.4%). Recurrences did not occur in this group of patients. Electrophysiological and color vision tests were performed in the initial phase of the disease, but we found no correlation between the test results and the final visual acuity.

Factors affecting magnitude and time course of neuromuscular block produced by suxamethonium

This study was designed to identify factors that significantly alter the magnitude and duration of suxamethonium-induced neuromuscular block in patients with an apparently normal genotype for pseudocholinesterase. One hundred and fifty-six adults (ages 18-65 yr) were allocated to 13 subgroups. Patients in each subgroup received suxamethonium 50-2000 micrograms kg-1. The mechanographic response of the adductor pollicis brevis muscle to ulnar nerve stimulation was recorded. The ED50 was found to be 167 micrograms kg-1, ED90 was 316 micrograms kg-1 and ED95 was 392 micrograms kg-1. The duration of action (delta t) was in agreement with earlier published results. The magnitude of block was dose-related and decreased with increasing onset time (ton) and pseudocholinesterase activity (PChA). Neither age nor gender affected the degree of suxamethonium-induced block. Delta t was dose-related, decreased with increasing PChA, and was shorter for women. Age and ton had no effect on delta t.

Coronary artery bypass grafting using two different anesthetic techniques: Part 3: Adrenergic responses

Twenty patients were studied during and after coronary artery bypass grafting (CABG). The patients were randomly assigned to two groups. In 10 patients, intraoperative general anesthesia (GA) was based on a combination of intravenous (IV) sufentanil and midazolam. In 10 other patients, thoracic epidural analgesia (TEA) with 0.375% bupivacaine plus sufentanil, 1:200,000 (5 micrograms/mL), and intraoperative GA with midazolam/N2O were used. During the prebypass period, lower heart rates (HR), less variability in mean arterial pressure (MAP), and systemic vascular resistance (SVR) was accompanied by less variability in plasma norepinephrine (NE) concentrations in the TEA group. Although no differences were observed between the groups in perfusion pressure and the amount of vasoactive drugs used during the bypass period, variability in SVR was less in the TEA group. This was accompanied by less increase in NE and less variability in epinephrine (E) plasma concentrations. However, cortisol (Co) release was higher during this period in the TEA group. Weaning from bypass was accompanied by higher MAP and SVR in the TEA group at a lower HR, whereas no differences were observed in the E, NE, and Co plasma concentrations between the groups. During the first and second postoperative days, better pain relief and lower E and Co plasma concentrations were found in the TEA group. It can be concluded that better hemodynamic stability during the prebypass and bypass periods was accompanied by less E and NE release during these periods. Co release in the TEA group was higher during the bypass period. Weaning from bypass was characterized by better hemodynamics in the TEA group.(ABSTRACT TRUNCATED AT 250 WORDS)

Acupuncture and transcutaneous stimulation analgesia in comparison with moderate-dose fentanyl anaesthesia in major surgery. Clinical efficacy and influence on recovery and morbidity

The efficacy of acupuncture and transcutaneous stimulation analgesia, supplemented by small doses of fentanyl (mean 1.2 micrograms/kg, SD 1.7) was compared with moderate-dose fentanyl anaesthesia (mean 22.9 micrograms/kg, SD 2.8) in 29 patients who underwent surgery for retroperitoneal lymph node dissection. The present study describes the anaesthetic techniques and comparison of haemodynamics, demand for analgesics after surgery, recovery and blood gases, restoration of urinary and bowel functions, convalescence in terms of self-reliance and the postoperative course in respect of fatigue and morbidity. A more rapid return of consciousness, an absence of hypercapnia and a smaller decrease in pH were observed in patients who received acupuncture and transcutaneous stimulation (p less than 0.05). No clinically relevant disadvantages attributable to the method were demonstrated.