An unusual toxic reaction to axillary block by mepivacaine with adrenaline

An increase in blood pressure, accompanied by atrial fibrillation, agitation, incomprehensible shouts and loss of consciousness, was observed in an elderly, ASA classification group II, cardiovascularly medicated male, 12 min after performance of axillary block with mepivacaine 850 mg containing adrenaline 0.225 mg, for correction of Dupuytren's contracture. After intravenous administration of labetalol, metoprolol and midazolam the patient's condition improved, and 15 min later he woke up. The block was successful and surgery was conducted as scheduled despite persisting atrial fibrillation. Postoperatively, the patient refused DC cardioversion and was treated medically. Both the temporal relationship of events and the response to treatment suggest that a rapid systemic absorption of mepivacaine with adrenaline and/or interaction of these drugs with the patient's cardiovascular medications were responsible for the perioperative complications.     

Effects of CO2 and adrenaline on 1% lidocaine in axillary block]

Rates of asthma are increasing in adults and children. In some pediatric institutions, asthma is the most common admitting diagnosis. At University of Chicago Children's Hospital (UCCH), at the University of Chicago Hospitals, the use of helium-oxygen mixtures (heliox) has been explored for treatment of children in status asthmaticus. Helium has a low density, and therefore has an increased flow rate which results in less airway resistance, decreased work of breathing, minimized airway collapse, and less hyperinflation. Little research on heliox and asthma has been done with children. A small study of children with status asthmaticus at the University of Chicago Children's Hospital found heliox resulted in improved peak flow readings and reductions in dyspnea and pulsus paradoxus. Nursing care of the child receiving heliox includes the use of appropriate delivery devices; monitoring temperature and other potential side effects; educating the child and family; and regularly assessing the following: pulse oximetry readings, heart and respiratory rates, blood pressure, and pulsus paradoxus.     

Correlation between evoked motor response of the sciatic nerve and sensory blockade

OBJECTIVE: The development of collateral microvessels following therapeutic angiogenesis with vascular endothelial growth factor (VEGF) was investigated using a new system of microangiography that employs monochromatic synchrotron radiation (SR) and a high definition video system to visualize arteries with a spatial resolution of 30 microns. METHODS: Ischemia was induced in the hindlimb of 20 rats by excision of the femoral artery, followed by transfection of the plasmid (400 micrograms) encoding VEGF or beta-galactosidase (control) into limb muscles. Microangiography was used to assess the development of collaterals in the ischemic limb four weeks after treatment. RESULTS: Gene transfer of VEGF produced morphologically similar, but significantly more extensive, collateral networks at the microvascular level as compared with the naturally occurring collateral arteries in the control animals (angiographic score: 0.88 +/- 0.08 versus 0.54 +/- 0.05, p < 0.01). No adverse vascular effects such as hemangiomas and/or arteriovenous (AV) fistulae were observed following VEGF treatment. The vasodilator effect of papaverine was evident in relatively large vessels in both groups. At the microvascular level (diameter < 100 microns), however, papaverine induced significant vasodilation in the VEGF-treated animals, and almost no vasodilation in the controls. CONCLUSIONS: SR microangiography allowed us to assess the development of small collateral arteries following VEGF-gene transfer. The information obtained may provide new insights regarding the collateral microcirculation and therapeutic angiogenesis.     

Addition of fentanyl to 1.5% lidocaine does not increase the success of axillary plexus block

The stroke volume of the left ventricle (SV) was calculated from noninvasive recordings of the arterial pressure using a finger photoplethysmograph and compared to the values obtained by pulsed Doppler echocardiography (PDE). A group of 19 healthy men and 12 women [mean ages: 20.8 (SD 1.6) and 22.2 (SD 1.6) years respectively] were studied at rest in the supine position. The ratio of the area below the ejection phase of the arterial pressure wave (A(s)) to SV, as obtained by PDE, yielded a "calibration factor" dimensionally equal to the hydraulic impedance of the system (Zao = A(s).SV-1). The Zao amounted on average to 0.062 (SD 0.018) mmHg.s.cm-3 for the men and to 0.104 (SD 0.024) mmHg.s.cm-3 for the women. The Zao was also estimated from the equation: Zao = a.(d + b.HR + c.PP + e.MAP)-1, where HR was the heart rate, PP the pulse pressure, MAP the mean arterial pressure and the coefficients of the equation were obtained by an iterating statistical package. The value of Zao thus obtained allowed the calculation of SV from measurements derived from the photoplethysmograph only. The mean percentage error between the SV thus obtained and those experimentally determined by PDE amounted to 14.8 and 15.6 for the men and the women, respectively. The error of the estimate was reduced to 12.3 and to 11.1, respectively, if the factor Zao, experimentally obtained from a given heart beat, was subsequently applied to other beats to obtain SV from the A(s) measurement in the same subject.     

Quantitative analysis of respiratory, motor, and sensory function after supraclavicular block

The incidence and clinical significance of hemidiaphragmatic paresis after supraclavicular block of the brachial plexus is unknown. Eight healthy volunteers received a supraclavicular block with a standard technique using 30 mL of 1.5% lidocaine. Respiratory function was assessed with ultrasound of the diaphragm, respiratory inductive plethysmography (RIP), and pulmonary function tests (PFT) every 20 min. Sensory block was assessed with pinprick and motor block with isometric force dynamometry every 20 min. Four of eight subjects demonstrated hemidiaphragmatic paresis on both ultrasound and RIP. No subject experienced changes in PFT values or subjective symptoms of respiratory difficulty. Motor and sensory blockade outlasted hemidiaphragmatic paresis. These results are contrasted to the often symptomatic, 100% incidence of hemidiaphragmatic paresis seen after interscalene block. In this study of healthy volunteers, supraclavicular block was associated with a 50% incidence (95% confidence interval 14-86) of hemidiaphragmatic paresis that was not accompanied by clinical evidence of respiratory compromise. Implications: Interscalene block is always associated with diaphragmatic paralysis and respiratory compromise. The significance of these side effects after supraclavicular block is unknown. Using sensitive measures of respiratory function, we determined that diaphragmatic paralysis occurs less often with the supraclavicular approach and is not associated with respiratory difficulties in healthy subjects.     

Genetics and pathophysiology of hereditary motor and sensory neuropathy type 1

Hereditary motor and sensory neuropathy type 1 (HMSN1) is the most common, but genetically heterogenous demyelinating peripheral neuropathy. HMSN1A is caused in most cases by a 1.5-Mb tandem duplication in chromosome 17p11.2. Hereditary neuropathy with liability to pressure palsies is caused by the reciprocal deletion of the 1.5-Mb HMSN1A region. The peripheral myelin protein22 (PMP-22) gene is located within the HMSN1A region and has a point mutation in non-duplicated HMSN1A patients. HMSN1B patients have a mutation in the protein zero (P0) gene located on chromosome 1q22-23 Point mutation in PMP-22 or P0 is also reported in patients with Dejerine-Sottas disease. In X-linked HMSN1 patients (HMSNX1) a mutation occurs in the connexin 32 gene located on chromosome Xq13. The morphological phenotype is different among the genotypes of HMSN1.     

Repeated episodes of transient radiating back and leg pain following spinal anesthesia with 1.5% mepivacaine and 2% lidocaine

Various chitinases have been identified in plants and categorized into several groups based on the analysis of their sequences and domains. We have isolated a tobacco gene that encodes a predicted polypeptide consisting of a 20-amino acid N-terminal signal peptide, followed by a 245-amino acid chitinolytic domain. Although the predicted mature protein is basic and shows greater sequence identity to basic class I chitinases (75%) than to acidic class II chitinases (67%), it lacks the N-terminal cysteine-rich domain and the C-terminal vacuolar targeting signal that is diagnostic for class I chitinases. Therefore, this gene appears to encode a novel, basic, class II chitinase, which we have designated NtChia2;B1. Accumulation of Chia2;B1 mRNA was induced in leaves in association with the local-lesion response to tobacco mosaic virus (TMV) infection, and in response to treatment with salicylic acid, but was only slightly induced by treatment with ethephon. Little or no Chia2;B1 mRNA was detected in roots, flowers, and cell-suspension cultures, in which class I chitinase mRNAs accumulate to high concentrations. Sequence comparisons of Chia2;B1 with known tobacco class I and class II chitinase genes suggest that Chia2;B1 might encode an ancestral prototype of the present-day class I and class II isoforms. Possible mechanisms for chitinase gene evolution are discussed.     

A double-blind comparison of ropivacaine, bupivacaine, and mepivacaine during sciatic and femoral nerve blockade

Antineoplastons A10 and AS2-1 exhibit growth inhibition of cancer cells by diverse modes of action. We observed antitumor responses within 2-3 weeks of a combination treatment of chemoradiation therapy and antineoplastons A10 and AS2-1 in phase I clinical study being conducted in Kurume University Hospital. We reviewed 3 clinical cases of advanced cancer (multiple metastatic lung cancer, thalamic glioma and primary lung cancer) in which we believed antineoplaston A10 and AS2-1 may be contributing to the rapid antitumor response. The possible use of this combination for induction therapy in advanced cancer is discussed.     

Gastric motor and sensory function testing

Structural properties of an equilibrium intermediate formed upon urea-induced unfolding of more ordered staphylococcal nuclease A-forms (A2 and A3) are studied. The effect of association on the structural properties and conformational stability of this unfolding intermediate is also considered. A close structural similarity (including tendency for association) is shown between this intermediate and the least ordered A1-form, induced in the acid-unfolded nuclease by moderate sulfate or chloride concentrations.     

A comparison of 2% and 1% formulations of propofol for the induction and maintenance of anaesthesia in surgery of moderate duration

This study, conducted in 110 patients undergoing surgery of moderate duration, compared the pharmacodynamic equivalence, efficacy and safety of 1% and 2% formulations of propofol. Anaesthesia was induced with propofol 2 mg.kg-1 given over 40 s and supplementary bolus injections of propofol were given if needed. There were no significant differences between the groups in mean induction times, total induction doses of propofol, frequency and mean duration of apnoea, fentanyl requirements or mean recovery times (times to eyes opening and to orientation). Isolated statistically significant group differences in systolic and diastolic blood pressures and heart rates during induction were not considered clinically significant. Discomfort on injection occurred in 40% and 52% of those given 1% (n = 55) and 2% (n = 55) propofol, respectively; there was no statistically significant group difference in severity. No major adverse effects were reported. This study showed that the 2% formulation has a similar safety and pharmacodynamic profile to the 1% formulation.     

Naloxone blockade of morphine analgesia: a dose-effect study of duration and magnitude

The thioxanthene neuroleptic, cis-chlorprothixene, was approximately 200 times more potent than its transisomer as an inhibitor of the aggregation of human blood platelets induced by 5-hydroxytryptamine (5HT). Against the active uptake of 5HT by these cells, however, trans-chlorprothixene was twice as inhibitory as its cisisomer, and this inhibition was found to be competitive. It is suggested that 5HT adopts different conformations for binding to its two platelet receptors.     

Timing of skilled motor performance: Tests of the proportional duration model.

Historically, theories of motor control have been based on either central or peripheral mechanisms. This article examines a current, explicit, central theory accounting for the observed flexibility in motor performance: the generalized motor program with a multiplicative rate parameter. Reanalysis of data from a variety of motor skills reported in the literature and a detailed study of skilled typewriting show that a generalized motor program with a multiplicative rate parameter generally does not fit observed performance. Instead, the data support a composite model of motor control in which performance is determined by both central and peripheral mechanisms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Symmetry of normal motor and sensory nerve conduction measurements

Nerve conduction measurements in normal subjects are assumed to be symmetric, but the normal limits of symmetry have not been determined. Full data on the limits of symmetry for commonly studied nerves are important in the clinical interpretation of nerve conduction data. We selected normal electrodiagnostic studies from archived electromyographic laboratory reports that included bilateral measurements of motor and sensory nerves. Symmetry of nerve conduction measures was confirmed, and only the median and ulnar sensory nerves had significant deviations from symmetry, supporting subclinical nerve damage in the most common dominant hand. The limits of symmetry were determined by calculating the 95th percentile for the differences between sides. For motor and sensory nerves, the range of 95th percentile limits was narrower for measures in upper extremity nerves compared to lower extremity nerves. Several reasons are offered for the wider limits of symmetry in lower extremity nerves.     

Quantitative assessment of differential sensory blockade after lumbar epidural lidocaine

A cutaneous current perception threshold (CPT) sensory testing device measures both large and small diameter sensory nerve fiber function and may be useful in evaluating differential neural blockade. Eight subjects received both lumbar epidural saline and lumbar epidural lidocaine. Five milliliters of normal saline was administered and the CPTs were measured. After the saline, 10 mL of 2% plain lidocaine was administered. CPTs, and sensation to touch, pinprick, and cold were subsequently measured. Saline had no effect on any measurements. Lidocaine caused an increase in all CPTs at the umbilicus and the knee reaching a statistical significance at 5 Hz for the umbilicus only. The great toe showed a slight increase of the 5 Hz stimulus and no increase of the 2000 or 250 Hz stimulus. There was a significant decrease in touch, pinprick, and cold sensation at the umbilicus and knee and a significant decrease in the cold sensation at the great toe. There was no effect on any measurements made at the mastoid. Epidural lidocaine resulted in a differential neural blockade as measured by a CPT monitor but not with crude sensory measurements.     

Electrophysiological evidence of developmental changes in the duration of auditory sensory memory

In behavioral studies, children's memory for tonal frequency has been found to persist for less time than adults' (T. A. Keller & N. Cowan, 1994). The present study was done to evaluate the argument that this effect is due to changes in auditory sensory memory and not to attentional mechanisms. This question was investigated using mismatch negativity (MMN), an auditory event-related potential considered to be insensitive to attention. Participants were 6-7-, 8-10-, and 11-12-year-old children and adults. They were presented with trains of stimuli, beginning with either a standard (1000 Hz) or a deviant (1200 Hz) tone with trains separated by either 1 s or 8 s. All 4 groups exhibited MMNs after delays of 1 s, but only the adults and oldest children exhibited MMNs after 8 s, indicating that there are maturational changes in the duration of auditory sensory memory.     

Hyperventilation alters colonic motor and sensory function: effects and mechanisms in humans

BACKGROUND & AIMS. Hyperventilation-induced hypocapnia affects hemodynamic function and enhances colonic motility. The aims of this study were to determine the effects of hypocapnic hyperventilation on colonic motility and sensation in health and to explore the putative neurohumoral mechanisms. METHODS: In experiment 1, colonic tone, sensation, plasma levels of cortisol, beta-endorphin, selected gut neuropeptides, norepinephrine, epinephrine, and splanchnic blood volume were measured during two sequences of hypocapnic hyperventilation. In experiment 2, colonic tone and sensation were assessed during eucapnic hyperventilation and abdominal compression. RESULTS: Hypocapnic hyperventilation, but not eucapnic hyperventilation or abdominal compression, significantly increased colonic tone and sensitivity to balloon distention (P = 0.017) without altering humoral mediators or splanchnic blood volume. Plasma norepinephrine level increased (P = 0.017) and splanchnic blood volume decreased (P = 0.028) during 5 minutes after hyperventilation, consistent with homeostatic responses. CONCLUSIONS: Increased colonic tone and sensation during hypocapnic hyperventilation are not caused by colonic compression. These effects of hyperventilation are not mediated humorally but may result from direct metabolic effects of hypocapnia on colonic muscle or from changes in central autonomic control of colonic smooth muscle.     

Alkalinization of lidocaine does not hasten the onset of axillary brachial plexus block

We assessed the onset of sensory and motor blockade as well as the distribution of sensory blockade after axillary brachial plexus block with 1.5% lidocaine hydrochloride 1:200,000 epinephrine with and without sodium bicarbonate in 38 patients. The onset of analgesia and anesthesia was recorded over the distributions of the median, ulnar, radial, and medial cutaneous nerves of the forearm, medial cutaneous and lateral cutaneous nerves of the arm, and musculocutaneous nerve. The onset of motor blockade of elbow and wrist movements was also recorded. Data were analyzed by using survival techniques and compared by using log rank tests. Only the onset of analgesia in the medial cutaneous nerves of the arm and forearm, and the onset of anesthesia in the medial cutaneous nerve of the arm were significantly faster (P < 0.05) with alkalinization of lidocaine. Our study showed that alkalinization of lidocaine does not significantly hasten block onset in most terminal nerve distributions. IMPLICATIONS: We examined whether alkalinizing a local anesthetic would quicken the onset of a regional upper limb nerve blockade. We found that alkalinization of lidocaine did not offer a significant clinical advantage in axillary brachial plexus blockade.     

Anatomic basis of continuous axillary block of the brachial plexus with thoracic reservoir

Although continuous axillary block is effective for periods of up to four to six weeks, pain clinic patients with severe chronic pain in the upper extremities, mainly resulting from neuropathic disease, can require continuous drug delivery by catheter-reservoir for up to three months or longer. We studied possible locations for implanting reservoirs or catheters from the perivascular axillary space in fresh cadavers, checking for possible vascular or nerve damage after applying the usual technique for reservoir implantation. The ideal location for the reservoir is the subcutaneous tissue of the homolateral infraclavicular space of the anterior side of the thorax. The customary procedures for inserting the catheter along the subcutaneous route that extends from the perivascular axillary space to the reservoir carry no risk of damaging vascular or nerve structures.     

Calcium channel subtypes in lamprey sensory and motor neurons

Pharmacologically distinct calcium channels have been characterized in dissociated cutaneous sensory neurons and motoneurons of the larval lamprey spinal cord. To enable cell identification, sensory dorsal cells and motoneurons were selectively labeled with fluorescein-coupled dextran amine in the intact spinal cord in vitro before dissociation. Calcium channels present in sensory dorsal cells, motoneurons, and other spinal cord neurons were characterized with the use of whole cell voltage-clamp recordings and specific calcium channel agonist and antagonists. The results show that a transient low-voltage-activated (LVA) calcium current was present in a proportion of sensory dorsal cells but not in motoneurons, whereas high-voltage-activated (HVA) calcium currents were seen in all neurons recorded. The different components of HVA current were dissected pharmacologically and similar results were obtained for both dorsal cells and motoneurons. The N-type calcium channel antagonist omega-conotoxin-GVIA (omega-CgTx) blocked >70% of the HVA current. A large part of the omega-CgTx block was reversed after washout of the toxin. The L-type calcium channel antagonist nimodipine blocked approximately 15% of the total HVA current. The dihydropyridine agonist (+/-)-BayK 8644 markedly increased the amplitude of the calcium channel current. The BayK-potentiated current was not affected by omega-CgTx, indicating that the reversibility of the omega-CgTx effect is not due to a blockade of L-type channels. Simultaneous application of omega-CgTx and nimodipine left approximately 15% of the HVA calcium channel current, a small part of which was blocked by the P/Q-type channel antagonist omega-agatoxin-IVA. In the presence of the three antagonists, the persistent residual current (approximately 10%) was completely blocked by cadmium. Our results provide evidence for the existence of HVA calcium channels of the N, L, and P/Q types and other HVA calcium channels in lamprey sensory neurons and motoneurons. In addition, certain types of neurons express LVA calcium channels.     

Effects of sex steroids on sensory and motor spinal mechanisms

The male copulatory pattern uses muscles in the penis for erection and penile insertion, the lower trunk for pelvic thrusting, and the sex accessory organs for seminal emission. Organization of the nuclei controlling penile muscles is achieved through cell growth, dendritic arborization, and synaptogenesis, actions dependent on androgen but not estrogen. Testosterone (T) and dihydrotestosterone (DHT) but not estradiol (E2), stimulate pelvic thrusting vigor by synchronizing discharge of motoneurons innervating pelvic muscles. Pelvic thrusting rhythmicity, regulated by spinal interneurons, is produced in female rabbits by E2 or T but not by DHT. Reflex contraction of the seminal vesicles, due to penile insertion, is facilitated by androgen presumably by its effect on preganglionic neurons of the hypogastric nerve, located in the dorsal commissural nucleus.