Threshold-level repetitive transcranial electrical stimulation for intraoperative monitoring of central motor conduction.

OBJECT: The authors conducted a study to evaluate repetitive transcranial electrical stimulation (TES) to assess spinal cord motor tract function in individuals undergoing spine surgery, with emphasis on safety and efficacy. METHODS: Somatosensory evoked potentials (SSEPs) were elicited using standard technique. Muscle electromyographic values were measured in response to a three- or four-pulse train of stimulation delivered to the motor cortex via subdermal electrodes. They also evaluated whether changes in the minimum stimulus intensity (that is, threshold level) needed to elicit a response from a given muscle predict motor status immediately postoperatively, as well as whether changes in SSEP response amplitude and latency predict sensory status immediately postoperatively. Anesthesia was routinely induced with intravenous propofol and remifentanil, supplemented with inhaled nitrous oxide. Use of neuromuscular block was avoided after intubation. Satisfactory monitoring of muscle response to threshold-level repetitive TES was achieved in all but nine of the 194 patients studied. In contrast, cortical SSEP responses could not be elicited in 42 of 194 individuals. In cases in which responses were present, TES-based evoked responses proved to be extremely accurate for predicting postoperative motor status. Somatosensory evoked potential monitoring was nearly as accurate for predicting postoperative sensory status. There were frequent instances of postoperative motor or sensory deficit that were not predicted by SSEP- and TES-based monitoring, respectively. There were no adverse events attributable to TES-based monitoring, although since this study ended we have had a single adverse event attributable to threshold-level repetitive TES. CONCLUSIONS: Intraoperative threshold-level repetitive TES-based monitoring of central motor conduction has proven to be a simple, safe, and highly accurate technique for the prevention or minimization of inadvertent motor deficit during surgery involving the spine or spinal cord.

Anesthesia in the patient with parkinsonism.

Medical control of parkinsonism has resulted in a longer life expectancy and better quality of life for these patients, who are now presenting for surgical treatment of a variety of conditions. In addition to the risks associated with age, these patients are more prone to restrictive pulmonary problems. General anesthesia should be avoided when possible.

Alphadione (Althesin): a new induction agent.

The use of Althesin for induction of anaesthesia in 57 patients showed that it is a satisfactory induction agent. However, with the exception of rapid recovery with minimal after-effects, it has no major advantages over the commonly used barbiturates.

[Clinical evaluation of the new anesthetic "Ethrane"]. / Evaluation clinique d'un nouvel agent anesthésique "l'éthrane"

Seventy-four patients aged 14 months to 71 years, classified as ASA I and II were anesthetised with Ethrane for surgical interventions of mean duration 117 minutes. With the exception of 5 patients who were directly anesthetised with Ethrane, the others received Ethrane after induction with Penthiobarbitone. Maintenance of anesthesia was ensured with 1 to 4p. 100 concentrations of Ethrane and 33p. 100 oxygen and 66p. 100 nitrous oxide. Tracheal intubation was facilitated by injection of 1 mg/kg of succinylcholine. Induction with enflurane is rapid with no phenomena of excitation or irritation of the ear passages. The cardiovascular apparatus is stable with no arrythmia but an increase in heart rate of 11 to 50p. 100 is noted and in 41p. 100 of the cases hypotension of 35p. 100 of the intitial value. During spontaneous ventilation, a type of rapid and superficial respiration is observed with a flow volume of 5.3 ml/kg for an average frequency of 25/min. The arterial blood gases show slight hypercapnia. Myorelaxation is significant and better than that obtained with halothane. Coming round poses few problems apart from agitation in adolescents. Response to simple orders appears at 13 minutes. Trembling and rigidity occur in 41p. 100 of the cases for 5 to 30 minutes. From the hepatic point of view, no lastin enzyme changes were noted and no renal toxicity was demonstrated. Ethrane appears to be a good anesthetic agent but the few advantages mentioned means that it does not fulfil ideal conditions.

Anaesthetic complications in surgical out-patients.

This study reports retrospectively the post-anaesthetic complications in surgical out-patients. We have studied the incidence and severity of these complications during the first five post-operative days in 500 female patients who underwent tubal ligation by laparoscopy. The report shows that post-anaesthetic complications in surgical out-patients are frequent but of mild severity. Although they produced some discomfort for the patients most of them were of the opinion that the advantages of having the operation as out-patients made up for the discomfort.

PIP: The safety of outpatient surgery depends mainly on patient selection, the type of operation, and the anesthetic technique. Subjects of this study were 500 women who as outpatients underwent tubal electrocoagulation through a laparoscope. After an interval of 1 week to 4 months postoperatively, each was sent a questionnaire regarding postanesthetic complications. The questionnaire was returned by 418 patients (83.6%). Several anesthetic agents had been used. Premedication was given only to very nervous patients (18%). Atropine .4 mg was given to all just before the operation. The trachae of all patients were untubated after a dose of succinylcholine and in 60% of cases 3-6 mg of D-tubocurare. There were no immediate anesthetic complications. Most patients were discharged within 3 hours. Postanesthetic complications were common. Muscle pains occurred in 45%, many lasting 2-5 days. Sore throat followed in 28.2% but was usually mild. Headache, nausea, vomiting, cough, and sputum were noted in 8-17%. A mild dizziness was sometimes a complaint. Inability to concentrate was experienced by 30% of patients for over 2 days. In 32.9 %, return to usual work took up to 48 hours; in 57.9%, it was 2-5 days w hile the others required over 5 days. 81% of the patients reported that they would accept the procedure again, while 16.7% would refuse. Return to preoperative mental status usually took several days and in a few over 5 days. Too early use of alcoholic beverages or driving an automob ile were warned against. Most patients considered that the advantage of having the operation as outpatients made up for the discomforts.

Response to hypercapnia under ketamine anaesthesia.

The respiratory response to hypercapnia in dogs anaesthetized with ketamine was increased. This respiratory stimulation was most probably due to a direct effect of the drug on the medullary respiratory neurones. This effect was not modified by preanaesthetic medication pentobarbitone 5 mg/kg or morphine 0.1 mg/kg. Catecholamine response to hypercapnia was essentially the same as that reported by hypercapnic dogs anaesthetized with thiopentone.