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Acute thyroid crisis on induction of anaesthesia.

Thyroid crisis on induction of anaesthesia was treated with dantrolene, because of a mistaken diagnosis of malignant hyperthermia. There was immediate improvement after dantrolene with reduction in muscle rigidity, mental confusion and pyrexia. High circulating T4 has an effect on calcium flux across the sarcoplasmic reticulum and dantrolene may inhibit this pathological mechanism. We suggest the same dosage regimen as is used in the treatment of malignant hyperthermia.

Acute Disease↗

Hyperthermia associated with 3,4-methylenedioxyethamphetamine ('Eve').

A patient was admitted with hyperthermia, muscle rigidity, rhabdomyolysis and disseminated intravascular coagulation. He was initially thought to have taken 3,4-methylenedioxymethamphetamine (MDMA, 'Ecstasy'), but subsequent toxicology revealed the presence of 3,4-methylenedioxyethamphetamine (MDEA, 'Eve'), its sister drug, in his blood. Subsequent in vitro testing for malignant hyperthermia proved to be negative.

3,4-Methylenedioxyamphetamine↗

A comparison of remifentanil and alfentanil in patients undergoing major abdominal surgery.

The efficacy and safety of remifentanil and alfentanil for patients undergoing major abdominal surgery were compared. Premedicated patients received a loading dose of remifentanil (1.0 microgram.kg-1; n = 116) and a continuous infusion of 0.5 microgram.kg-1.min-1, or a loading dose of alfentanil (25 micrograms.kg-1; n = 118) and a continuous infusion of 1.0 microgram.kg-1.min-1. Propofol was administered (10 mg every 10 s) until loss of consciousness. Patients' lungs were ventilated with 66% nitrous oxide and 0.5% (end-tidal) isoflurane in oxygen. The study drug infusion rate was reduced by 50% 5 min after intubation. Alfentanil was discontinued 15 min before the end of surgery, whereas remifentanil was continued in the immediate postoperative period at a reduced dose. Responses to intubation (28%) and skin incision (17%) occurred approximately twice as often in the alfentanil group (15% and 8%; p = 0.014 and p = 0.037, respectively). More patients receiving alfentanil had one or more responses to surgery (72% vs. 57%; p = 0.016). The time to spontaneous respiration, adequate respiration, response to verbal command and time to recovery room discharge were similar. However, owing to decreased variability, the time to extubation was shorter with remifentanil than with alfentanil (p = 0.048). There was a similar overall incidence of adverse events in both groups, 82% and 75% of patients, respectively. Adverse events associated with remifentanil were rapidly controlled by dose reductions. The incidence of intra-operative hypotension and bradycardia was higher in the remifentanil group (p < or = 0.033). An initial remifentanil infusion rate of 0.1 microgram.kg-1.min-1 titrated to individual need provided postoperative pain relief in the presence of adequate respiration in 71% of patients. When using remifentanil in the immediate postoperative setting, rapid administration of bolus doses and infusion rate increases resulted in a relatively high incidence of muscle rigidity, respiratory depression and apnoea. Changing the postoperative regimen to avoid rapid changes in remifentanil blood concentration resulted in more effective analgesia and dramatically reduced the incidence of adverse events during this period. In patients undergoing major abdominal surgery, remifentanil appears to offer superior intra-operative haemodynamic stability during stressful surgical events compared with alfentanil without compromising recovery from anaesthesia. Remifentanil can be administered as a postoperative analgesic agent at a starting dose of 0.1 microgram-.kg-1.min-1; however, it should only be used in the presence of adequate supervision and monitoring of the patient. Administration of bolus doses is not recommended in this setting.

Abdomen↗

The effect of intravenous administration of variable-dose midazolam after fixed-dose ketamine in healthy awake cats.

The effects of intravenous administration of variable-dose midazolam and ketamine (3 mg/kg) were studied in twelve healthy unmedicated cats from time of administration until full recovery. A range of midazolam doses (0.0, 0.05, 0.5, 1.0, 2.0 and 5.0 mg/kg) was chosen, so that beneficial and/or detrimental effects could be documented and the therapeutic window for further study determined. One minute after administration of ketamine, all cats had assumed a lateral position, mostly with head up. Muscle tone was increased (100%), apneustic breathing pattern evident in 92% of cats, chewing without stimulation of the oropharyngeal area was observed in most cats (97%), but most cats did not salivate (87%). At 2.5 min after completion of ketamine injection and 1 min after administration of saline, a similar picture was observed, except that salivation was evident. All cats chewed or swallowed in response to a finger or laryngoscope placed in the oropharyngeal area and, while most cats were not aware of a noxious stimulus to the tail, some cats were aware of a noxious stimulus to the paw. Recovery from ketamine alone was rapid and smooth with cats rolling into sternal recumbency and then cautiously walking with ataxia. Recovery to walking without incoordination was also rapid (< 2 h) and no abnormal behavioural patterns were observed during recovery. Administration of midazolam after ketamine, had beneficial effects and the therapeutic window for midazolam was found to lie between 0.05 mg/kg and 0.5 mg/kg. Administration of any dose of midazolam after ketamine caused a greater proportion of cats to assume a laterally recumbent position with head down compared with ketamine alone, however, the time period of recumbency was only significantly longer with a midazolam dose of 2.0 mg/kg or above. Doses of midazolam of 0.5 mg/kg or above decreased muscle rigidity but did not affect salivation or respiratory pattern observed in cats which received ketamine alone. A significantly greater proportion of cats which received ketamine and midazolam 0.5 mg/kg or above did not swallow in response to a finger or a laryngoscope placed in the mouth compared with that which received ketamine alone. The length of time in which cats did not swallow was only significantly longer at midazolam doses of 1.0 mg/kg and above. At midazolam doses of 0.5 mg/kg or above, the proportion of cats without a nociceptive response to a tail or paw clamp was significantly greater than cats which received ketamine alone. The time period without nociceptive response, however, was not influenced by midazolam administration. The time taken for cats which received ketamine and midazolam 0.05 mg/kg or 0.5 mg/kg to assume sternal position, walk with ataxia, walk without ataxia, behave normally when approached or restrained and recover normal arousal state was not significantly different from cats which received ketamine alone. Ketamine and midazolam 5.0 mg/kg significantly prolonged all recovery times compared with ketamine alone. Unfortunately, a greater proportion of cats which received ketamine and midazolam 0.5 or 5.0 mg/kg exhibited detrimental behavioural effects. These were more likely to be adverse and included restlessness, vocalization and difficulty approaching and restraining cats. In this study, an effect of sex of the cats was found, with male cats taking a significantly longer to recover to sternal recumbency and walk with ataxia, while female cats took longer to recover to a normal arousal state.

Anesthetics, Dissociative↗

Fulminant metoclopramide induced neuroleptic malignant syndrome rapidly responsive to intravenous dantrolene.

We report a case of fulminant neuroleptic malignant syndrome in a man aged 70 developing within 12 hours of starting six-hourly intravenous metoclopramide. The muscle rigidity and hyperpyrexia were unresponsive to intravenous benztropine but resolved within one hour of intravenous dantrolene 2 mg/kg. Within six hours the patient had a partial relapse which resolved completely following further intravenous dantrolene 2 mg/kg. This case demonstrates that the rapid effect of intravenous dantrolene can be life saving in fulminant neuroleptic malignant syndrome.

Aged↗

Low doses of rocuronium during remifentanil-propofol-based anesthesia in children: comparison of intubating conditions.

BACKGROUND: In this prospective double-blind study, intubation conditions were compared at 90 s following two different low doses of rocuronium during remifentanil and propofol anesthesia in children undergoing ambulatory procedures. METHODS: Forty-four children (ASA I-II, aged 3-12 years) undergoing day case ENT surgery were premedicated with midazolam 0.5 mg x kg(-1). Following atropine 10 microg x kg(-1), remifentanil infusion 0.5 microg x kg(-1) x min(-1) was started. After 60 s, anesthesia was induced with propofol 2.5 mg x kg(-1). Immediately after a bolus dose of propofol, the children received rocuronium doses of 0.15 mg x kg(-1) (group I, n = 22) or 0.3 mg x kg(-1) (group II, n = 22) in a randomized manner, after which an infusion of propofol 6 mg x kg(-1) h(-1) was added to the infusion of remifentanil 0.5 microg x kg(-1) min(-1) for maintenance of anesthesia. Intubating conditions were evaluated 90 s after rocuronium administration applying the Copenhagen Scoring System which included components of laryngoscopy, vocal cord movement and reaction to intubation. Hemodynamic values were recorded at predetermined time intervals. RESULTS: Excellent, good and poor intubation conditions were 18.2, 40.9 and 40.9% in group I and 40.9, 54.5 and 4.5% in group II. Clinically acceptable intubating conditions (excellent and good) were significantly higher in group II (95.5%) than in group I (59.1%) (P = 0.004). Mean values of heart rate and blood pressure did not differ significantly between groups. No children required any intervention for hemodynamic instability and/or muscle rigidity. CONCLUSIONS: The results suggest that 0.3 mg x kg(-1) of rocuronium may be a better low dose than 0.15 mg x kg(-1) of rocuronium for clinically acceptable intubating conditions in pediatric ambulatory surgery during remifentanil-propofol-based anesthesia at the doses used in the study.

Ambulatory Surgical Procedures↗

Influence of different sitting positions and abduction orthoses on leg muscle activity in children with cerebral palsy.

A surface electromyogram (EMG) was recorded from four leg muscles to measure the effects of various seat inclinations and an abduction orthosis on eight children with cerebral palsy and controls during performance of an upper-extremity task and while listening to a story. EMG responses were lowest in the forward-leaning and horizontal positions with the abduction orthosis, and highest in reclined and horizontal positions without the orthosis for both groups of children during the performance of an upper-extremity task. While listening to a story, there was no median EMG activity in any muscles of the controls, but there were wide variations in those of the children with cerebral palsy. The results indicate that the use of an abduction orthosis and horizontal and forward-leaning seats decrease lower-extremity muscle activity, and so it is possible that it might also improve upper-extremity function.

Adolescent↗

Slowly progressive limb-kinetic apraxia with a decrease in unilateral cerebral blood flow.

We report two patients with slowly progressive motor disorders, whose principal manifestations were asymmetric limb-kinetic apraxia and muscle rigidity. In both patients MRI revealed no responsible lesion, whereas single photon emission computed tomography (SPECT) showed a decrease in cerebral blood flow (CBF) in the unilateral hemisphere. One patient with mainly right-sided apraxia had a decreased CBF in the left central region between the frontal and parietal cortices, and the other patient with left-sided apraxia in the right parietal cortex. In agreement with asymmetric clinical symptoms, the regional CBF decrease in the unilateral cortical areas including the frontal and parietal cortices may suggest a degenerative disease, presumably diagnosed as having cortico-basal degeneration.

Aged↗

The effects of neuromuscular stimulation on muscle tone at the knee in paraplegia.

Resting muscle tone of the leg was measured in terms of thigh muscle stiffness and knee resonant frequency in muscles of spinal cord injured subjects who had been involved in an electrical neuromuscular stimulation training programme of the thigh muscles over at least 2 months. The thigh circumference of these patients was 6.6% larger than before training commenced (P less than 0.001) and showed increased muscle stiffness and resonant frequency compared to a similar group of paralysed subjects who had not used any neuromuscular stimulation. Resonant frequency and stiffness after the long-term training were similar to those of non-injured controls and therefore the stimulation programme seemed to reverse the effects of paralysis on muscle tone. Short periods of rest (30 min) caused increased muscle stiffness in non-injured controls and paralysed muscles trained by neuromuscular stimulation. Additional 15 min periods of neuromuscular stimulation further increased muscle stiffness in the trained muscles but also in the muscles of paralysed subjects who had no long-term neuromuscular training. In contrast, 15 min sessions of passive movement of the knee decreased muscle stiffness in long-term trained paralysed muscles and untrained paralysed muscles. Knee resonant frequency was also significantly decreased in the trained paralysed muscles. Results show that muscle tone varies depending on the amount of previous movement or rest and that although neuromuscular stimulation of paralysed muscles increases muscle stiffness and knee resonant frequency, it is in fact restoring such properties of the muscle to a state approaching that of non-injured controls.

Adult↗

Identification of time-varying stiffness, damping, and equilibrium position in human forearm movements.

Knowledge of how stiffness, damping, and the equilibrium position of specific limbs change during voluntary motion is important for understanding basic strategies of neuromotor control. Presented here is an algorithm for identifying time-dependent changes in joint stiffness, damping, and equilibrium position of the human forearm. The procedure requires data from only a single trial. The method relies neither on an analysis of the resonant frequency of the arm nor on the presence of an external bias force. Its validity was tested with a simulated forward model of the human forearm. Using the parameter estimations as forward model input, the angular kinematics (model output) were reconstructed and compared to the empirically measured data. Identification of mechanical impedance is based on a least-squares solution of the model equation. As a regularization technique and to improve the temporal resolution of the identification process, a moving temporal window with a variable width was imposed. The method's performance was tested by (a) identifying a priori known hypothetical time-series of stiffness, damping, and equilibrium position, and (b) determining impedance parameters from recorded single-joint forearm movements during a hold and a goal-directed movement task. The method reliably reconstructed the original angular kinematics of the artificial and human data with an average positional error of less than 0.05 rad for movement amplitudes of up to 0.9 rad, and did not yield hypermetric trajectories like previous procedures not accounting for damping.

Acceleration↗

Pharmacokinetics of morphine infusion in premature neonates.

Morphine pharmacokinetics were studied in 17 premature neonates (26-34 weeks' gestation) after intravenous infusion during the first 24 hours of life. Infants received either standard dose morphine that comprised of a 100 micrograms/kg/hour loading infusion for 2 hours followed by a maintenance infusion of 12.5 micrograms/kg/hour, or a high dose of 200 micrograms/kg/hour for 2 hours followed by 50 micrograms/kg/hour. Mean plasma concentrations of morphine (SD) after 2 and 24 hours were 99 (12.9) and 96.4 (3.2) ng/ml, and 184.2 (37.7) and 319 (71.2) ng/ml for the standard and high dose regimens, respectively. Morphine-3-glucuronide plasma concentrations achieved about 20% and 80% of morphine values at 2 and 24 hours respectively. Morphine-6-glucuronide could not be detected at 2 hours, but attained 20-25% of morphine plasma concentrations by 24 hours. The population mean morphine clearance was 2.4 ml/min/kg, the elimination half life was 8.75 hours and the volume of distribution was 1.82 1/kg. High plasma concentrations of morphine appeared to be well tolerated. Although mean arterial blood pressure decreased during the first six hours of treatment, this was not statistically significant; two infants experienced transient muscle rigidity, but no evidence of seizures was noted. There appears to be no clinical advantage in using the high dose regimen.

Blood Pressure↗

Interactions of L-dopa and amantadine in patients with Parkinsonism.

Twenty-seven patients with Parkinson's disease participated in a double-blind crossover trial of L-dopa and amantadine. Each drug was given for six weeks, and six weeks were allowed to elapse between the two periods of treatment. Marked improvement occurred in patients given L-dopa first, whereas no clinical effect was observed in those patients treated first with amantadine. L-dopa was less beneficial to patients who had previously received amantadine, whereas amantadine became effective in patients who had previously taken L-dopa. The effect of pre-treatment with one drug on the therapeutic effectiveness of the other drug is reflected in changes of homovanillic acid levels in the cerebrospinal fluid.

Amantadine↗

An analysis of six patients with Parkinson's disease who have been unresponsive to L-dopa therapy.

Six patients diagnosed as Parkinson's disease on a clinical basis alone are described, and their response to L-dopa and to alpha methyl dopa hydrazine (MK 486) and L-dopa. They are compared with 239 other patients with Parkinson's disease treated in the same time period. These six patients were unusual in that they did not have a clinical response to L-dopa, nor did they develop dyskinesias on L-dopa or on L-dopa with MK 486, although they showed high blood levels of L-dopa and high homovanillic acid levels in the spinal fluid. Unresponsiveness to L-dopa is attributed to a specific brain mechanism and not to problems of transport of L-dopa to the brain or to abnormal peripheral metabolism of L-dopa. The term `motor unresponsiveness to L-dopa' may be useful to describe such patients who may eventually be shown to be suffering from diseases other than Parkinsonism.

Aged↗

Stiff-man syndrome associated with nocturnal myoclonus and epilepsy.

A case of stiff-man syndrome associated with primary generalised epilepsy is reported. In addition, nocturnal polygraphic recording revealed a nocturnal myoclonus. Detailed examination of the central nervous system did not show specific changes. There is no direct proof as to a spinal or supraspinal origin of the stiff-man syndrome. The absence of specific anatomical lesions may indicate a functional rather than a structural disturbance in its physiopathogenesis.

Brain↗