Requirement for Discharge in the Care of a Responsible Adult in Procedural Sedation in the Emergency Department: Necessity or Potential Barrier to Health Equity?

BACKGROUND

Procedural sedation is commonly practiced by emergency physicians to facilitate patient care in the emergency department (ED). Although various guidelines have modernized our approach to procedural sedation, many procedural sedation guidelines and practices still often require that patients be discharged into the care of a responsible adult.

DISCUSSION

Such requirement for discharge often cannot be met by underserved and undomiciled patients. Benzodiazepines, opioids, propofol, ketamine, "ketofol," etomidate, and methohexital have all been utilized for procedural sedation in the ED. For patients who may require discharge without the presence of an accompanying responsible adult, ketamine, propofol, methohexital, "ketofol," and etomidate are ideal agents for procedural sedation given rapid onsets, short durations of action, and rapid recovery times in patients without renal or hepatic impairment. Proper pre- and postprocedure protocols should be utilized when performing procedural sedation to ensure patient safety. Through the use of appropriate medications and observation protocols, patients can safely be discharged 2 to 4 h postprocedure.

CONCLUSION

There is no pharmacodynamic or pharmacokinetic basis to require discharge in the care of a responsible adult after procedural sedation. Thoughtful medication selection and the use of evidence-based pre- and postprocedure protocols in the ED can help circumvent this requirement, which likely disproportionally impacts patients who are of low socioeconomic status or undomiciled.

Electroconvulsive Therapy Anesthetic Choice and Clinical Outcomes

OBJECTIVE

Etomidate and methohexital are the 2 commonly used anesthetics for electroconvulsive therapy (ECT) in the United States. The objective of this study was to examine how anesthetic choice between etomidate and methohexital is associated with real-world clinical outcomes.

METHODS

This naturalistic retrospective cohort study examined longitudinal electronic health records for 495 adult patients who received 2 or more ECT treatments from 2010 to 2019 in Kaiser Permanente North California, a large integrated health care system. Study outcomes included 12-month posttreatment depression remission as measured by the 9-item Patient Health Questionnaire, psychiatric and all-cause emergency department visits, and psychiatric and all-cause hospitalizations.

RESULTS

Anesthetic choice was not significantly related to depression severity, emergency department visits, or psychiatric hospitalizations at 12 months after completing ECT. In exploratory analyses, we found that etomidate compared with methohexital was associated with higher rates of patient discomfort adverse effects-postictal agitation, phlebitis, and myoclonus (2.4% vs 0.4%; P < 0.001).

CONCLUSIONS

We present the first large comparison of etomidate and methohexital as anesthetics for ECT and their associations with real-world outcomes. Our study showed no significant difference on depression remission, emergency department visits, or hospitalizations 12-months posttreatment. Thus, clinicians should focus on other patient or treatment characteristics when deciding on anesthetics for ECT. Further investigation is needed to confirm our exploratory findings that etomidate use was correlated with a higher rate of patient discomfort adverse effects relative to methohexital.

General intravenous anesthetics - pharmacodynamics, pharmacokinetics and chiral properties

In continuation of our published review on general inhalational anesthetics, the current article presents a survey of intravenous agents for general anaesthesia. From chemical point of view these compounds belong to structurally diverse categories, such as barbiturates - thiopental (Sodium pentothal®, Trapanal®, Pentothal®), methohexital (Brevital®), and hexobarbital (Evipan®, Hexenal®, Citopan®, Tobinal®); non-barbiturate derivatives - ketamine (Ketalar® Ketaset®), esketamine (Ketanest®), and etomidate (Amidate®, Hypnomidate®), phenolic derivatives - propofol (Diprivan®); steroid derivatives - mixture of alfadolone and alfaxalone (Althesin® in human and Saffan® in veterinary anesthesia); and derivatives of phenylacetic acid - propanidid (Epontol®, Sombrevin®). Most of these compounds are chiral, with the exception of propofol and propanidid. Apart from etomidate and esketamine, they are used in the form of their racemates. Besides their characteristics and mechanism of action, attention is centred also on their chiral properties.

A Comparison of Etomidate, Ketamine, and Methohexital in Emergency Department Rapid Sequence Intubation

BACKGROUND

Rapid sequence intubation (RSI) is routinely used for emergent airway management in the emergency department (ED). It involves the use of induction, and paralytic agents help facilitate endotracheal tube placement.

OBJECTIVE

In response to a previous national drug shortage resulting in the use of alternative induction agents for RSI, we describe the effectiveness and safety of ED RSI with ketamine or methohexital compared with etomidate.

METHODS

We conducted a retrospective, single-center observational study from March 1-August 31, 2012 describing RSI with etomidate, ketamine, and methohexital. All adult patients undergoing RSI in the ED who received etomidate prior to its shortage and methohexital or ketamine during the shortage were included.

RESULTS

The study included 47, 9, and 26 patients in the etomidate, ketamine, and methohexital groups, respectively. Successful intubation on the first attempt occurred in 74.5%, 55.6%, and 73.1% of the etomidate, ketamine, and methohexital groups, respectively. The mean number of intubation attempts and time to intubation seemed to be similar in all groups. At least three intubation attempts were required in 22.2% and 7.7% of the ketamine and methohexital groups, respectively, compared with none in the etomidate group. Two aspirations were observed in the etomidate group.

CONCLUSION

Methohexital and etomidate had similar rates of successful intubation on the first attempt and seem to be more effective than ketamine. Etomidate may reduce the need for three or more intubation attempts. Larger, prospective studies are needed to determine if ketamine or methohexital are more effective than etomidate for RSI.

Transcranial motor evoked potential changes induced by provocative testing during embolization of cerebral arteriovenous malformations in patients under total intravenous anesthesia

Cerebral motor evoked potential (MEP) monitoring during arteriovenous malformation (AVM) embolization is not well studied (Söderman et al. 2003). Alterations of cerebral blood flow (CBF) during cerebral embolization could cause ischemia/infarction to the cerebral cortex. Permanent loss of MEPs is correlated with a permanent motor deficit. We report a case of a patient undergoing AVM embolization during which transcranial electrical motor evoked potentials (TCeMEP) reliably predicted changes to CBF induced by selective methohexital testing. Our finding demonstrated that MEPs are a useful means of intraoperative monitoring of motor pathway integrity and predicting changes. The loss of MEP predicted and prevented severe postoperative motor deficits. Intraoperative neuromonitoring with SSEP, TCeMEP and continuous EEG revealed no changes until the posterior cerebral artery (PCA), but not the anterior cerebral artery (ACA), was injected. TCeMEP may be superior to somatosensory evoked potential (SSEP) and EEG monitoring in predicting motor impairment during AVM surgery.

Hippocampal memory function as reflected by the intracarotid sodium methohexital Wada test

The intracarotid amobarbital procedure (IAP) determines lateralization of memory function for predicting the risk of amnesia after epilepsy surgery. Shortages of amobarbital led to its substitution with sodium methohexital in the intracarotid methohexital procedure (IMP). We compared IAP scores (32 patients) with IMP scores (20 patients). Wada ipsilateral and contralateral memory scores were analyzed and compared, as was the relationship of these scores to the results of standard neuropsychological memory tests. There was no significant difference in Wada contralateral memory scores (first injection) between the IAP and IMP. Differences between the IAP and IMP in memory scores for the hemisphere ipsilateral to the epileptogenic focus (second injection) were significant (P=0.01), patients who underwent the IMP manifesting a higher ipsilateral memory reserve. IAP scores related better to standard neuropsychological memory test scores than did IMP scores. The anesthetic drug used in Wada testing may affect lateralized memory assessment and prediction of postsurgical memory changes.

Effects of propofol vs methohexital on neutrophil function and immune status in critically ill patients

PURPOSE

Patients with severe brain injury often require long-term sedation and have a high incidence of nosocomial infections, causing an increased mortality rate. However, whether anesthetic drugs might contribute to immunosuppressive effects remains unclear.

METHODS

In this prospective study, we investigated the effects of propofol (4-6 mg x kg(-1) x h(-1)) and methohexital (1-3 mg x kg(-1) x h(-1)) on neutrophil leukocyte function and immune status in 21 patients with brain injury who either received propofol (n = 12; 9 male, 3 female; mean age, 51 +/- 15 years) or methohexital (n = 9; 8 male, 1 female; mean age, 48 +/- 17 years) after admission to the intensive care unit (ICU). Both sedatives were administered over 7 days and individual dosage was adapted according to clinical requirements. Neutrophil leukocyte function was assessed as phagocytosis and respiratory oxidative burst activity. Furthermore, leukocyte subpopulations, and surface markers of lymphocytes and monocytes (CD3; CD4; CD45RO; CD4/CD45RO; CD25; CD4 and CD25; CD54; CD69; CD14/HLA-DR; CD8; CD3/HLA-DR; CD4 : CD8 ratio) were assessed. Blood samples were drawn on ICU admission, and on days 3, 7, and 14. Patients' demographics were compared by Wilcoxon test and laboratory results were compared by analysis of variance (ANOVA) for repeated measurements, with an all pairwise multiple comparison procedure.

RESULTS

There were no significant differences in neutrophil oxidative burst and phagocytosis within or between the two groups at the different time points. With respect to cellular markers of lymphocytes and monocytes, all values throughout remained in the normal range.

CONCLUSION

Methohexital and propofol exhibited no significant effects on neutrophil function and immune status in patients with severe brain injury requiring long-term sedation.

Bilateral bispectral index monitoring during suppression of unilateral hemispheric function

Bispectral Index (BIS) has been used to monitor level of "sedation" based on the electroencephalogram (EEG). Patients evaluated for surgery to control a seizure disorder undergo Wada testing, during which one hemisphere is rendered functionally inactive after injecting a short-acting barbiturate. We surmised that the BIS values would reflect these functional changes. Eight epileptic patients were enrolled. A full array of 21 EEG electrodes and 2 BIS XP (Quatro) strips over each frontal region of the scalp were applied. The EEG was continuously recorded. BIS values from each hemisphere were recorded every minute. Angiography was performed by advancing a catheter into each internal carotid artery. Amobarbital or methohexital was injected until the patient developed a hemiparesis. The EEG confirmed a significant lateralized cortical effect of the barbiturate. Repeated measures analysis of variance was used to analyze the differences between the BIS values from monitor electrode strips placed on the left (left BIS) and the right (right BIS) sides of the head as well as the differences in the left and right BIS values before and after each injection of the barbiturate. Injection of barbiturate into either the left or right internal carotid artery produced a significant change on the 21-electrode EEG. However, there was no difference between left BIS to right BIS values (P = 0.84). With repeated injections of barbiturates, some patients became sedated. At these times, both left BIS and right BIS values decreased together before and after injection of barbiturate. The BIS monitor was unable to distinguish significant hemispheric EEG and clinical functional changes except when the patient became sedated.

Randomized clinical trial of propofol versus methohexital for procedural sedation during fracture and dislocation reduction in the emergency department

Although methohexital has been well studied for use in emergency department (ED) procedural sedation (PS), propofol has been evaluated less extensively for ED use.

OBJECTIVE

The authors hypothesized that there is no difference in the depth of sedation and the rate of respiratory depression (RD) between propofol and methohexital in PS during the reduction of fractures and dislocations in the ED.

METHODS

This was a randomized prospective study of nonintoxicated adult patients undergoing PS for fracture or dislocation reduction in the ED between July 2001 and March 2002. Patients were randomized to receive either propofol or methohexital, 1 mg/kg intravenously, followed by repeat boluses of 0.5 mg/kg every 2 minutes until adequate sedation was achieved. Doses, vital signs, end-tidal CO(2) (ETCO(2)) by nasal cannulae, pulse oximetry, and bispectral electroencephalogram analysis (BIS) scores were recorded. RD was defined as an ETCO(2) greater than 50 torr, an oxygen saturation less than 90% at any time, or an absent ETCO(2) waveform. After returning to baseline mental status, patients completed three 100-mm visual analog scales (VASs) regarding pain associated with the procedure, recall of the procedure, and satisfaction. RD rates and VAS outcomes were compared with chi-square tests.

RESULTS

There were 109 patients enrolled; six were excluded for study protocol violations. Of the remaining 103 patients, 52 received methohexital (reduction successful in 94%) and 51 received propofol (98% successful). No cardiac rhythm abnormalities or significant decline in systolic blood pressure (>20%) was detected. Six patients required bag-valve-mask-assisted ventilations during the procedure, all for less than 1 minute; four of these patients received methohexital, and two received propofol. By the authors' definition, RD was seen in 25 of 52 (48%) patients receiving methohexital and 25 of 51 (49%) patients receiving propofol (p = 0.88). The mean minimum recorded BIS score was 66.2 (95% confidence interval [CI] = 62 to 70) for methohexital and 66 (95% CI = 60 to 71) for propofol. VAS results showed similar rates of reported pain, recall, and satisfaction for the two agents.

CONCLUSIONS

The authors were unable to detect a significant difference in the level of subclinical RD or the level of sedation by BIS between the two agents. The use of either agent seems to be safe in the ED.

Can the bispectral index be used to predict seizure time and awakening after electroconvulsive therapy?

The electroencephalogram (EEG) bispectral index (BIS) measures the hypnotic component of the anesthetic state and correlates with emergence from general anesthesia. Therefore, we hypothesized that the BIS would be useful in predicting electroconvulsive therapy (ECT)-induced seizure times and awakening from methohexital anesthesia. Twenty-five consenting patients with major depressive disorders underwent 100 maintenance ECT treatments. All patients were premedicated with glycopyrrolate 0.2 mg IV, and anesthesia was induced with methohexital 1 mg/kg IV. The BIS was monitored continuously, and the values were recorded at specific end-points, including before anesthesia (baseline), after the induction of anesthesia (pre-ECT), at the end of ECT (peak), after ECT (suppression), and on awakening (eye opening). The pre-ECT BIS value correlated with the duration of both the motor (r = 0.3) and EEG (r = 0.4) seizure activity (P < 0.05). The peak post-ECT BIS value correlated with the duration of the EEG seizure activity (r = 0.5) (P < 0.05). A positive correlation was also found between the EEG seizure duration and the time to eye opening (r = 0.4) (P < 0.05). However, the BIS values on awakening from methohexital anesthesia varied from 29 to 97 and were <60 in 75% of the cases. We conclude that the BIS value before the ECT stimulus is applied could be useful in predicting the seizure time. However, the BIS values on awakening were highly variable, suggesting that it reflects both the residual depressant effects of methohexital and post-ictal depression.

IMPLICATIONS

The bispectral index (BIS) value immediately before the electroconvulsive therapy (ECT) stimulus correlates with the duration of the motor and electroencephalogram (EEG) seizure activity during methohexital anesthesia. In addition, the increase in the BIS value during the ECT-induced seizure was proportional to the duration of EEG seizure activity. However, the BIS value on awakening from anesthesia varied widely, from 29 to 97.

Safety and effectiveness of methohexital for procedural sedation in the emergency department

Use of methohexital as an agent for moderate procedural sedation in the Emergency Department (ED) recently has increased. As a barbiturate, potential complications include respiratory and myocardial depression. We conducted a retrospective review of medical records and procedural flow charts for all use of methohexital in our ED during a 31-month period. We collected data on medication use, adjunctive medications, indications, procedural success, and complications. Overall, there were 114 orthopedic procedures performed using methohexital (mean dose of 1.43 mg/kg) for sedation on 104 patients. Procedures included shoulder dislocation reduction (26.3%), hip dislocation reduction (25.4%), elbow dislocation reduction (15.2%), and fracture reduction (25.4%). There was an 80.8% success rate with the first dose of methohexital. Complications occurred in 20.2% of patients and included oxygen desaturation, hypotension, hypoventilation, vomiting, tremor, and airway obstruction. All complications were transient and managed without sequelae. Use of concurrent parenteral opioid medications had no significant impact on success or complications.

A study of the Bispectral Index Monitor during procedural sedation and analgesia in the emergency department

STUDY OBJECTIVE

The Bispectral Index Monitor has been validated as an objective measure of sedation depth in the operating room; however, its value for states other than general anesthesia remains unclear. We hypothesized that bispectral index monitoring would reliably correlate with traditional definitions of sedation depth in emergency department patients undergoing procedural sedation and analgesia.

METHODS

In this prospective observational study we measured the Bispectral Index score and a modified Ramsay Sedation Scale score every 5 minutes in a convenience sample of adult ED patients undergoing procedural sedation and analgesia. Investigators and treating physicians were blinded to Bispectral Index scores, which were later correlated with modified Ramsay Sedation Scale scores. We constructed receiver operating characteristic curves to determine the most discriminatory Bispectral Index score thresholds for sedation depth.

RESULTS

Two hundred seventy paired readings were obtained from 37 patients. Despite being statistically significant (P <.0005), the correlation between the Bispectral Index Monitor and modified Ramsay Sedation Scale scores was only moderate (Spearman rho=-0.690) and displayed wide variability. A modified Ramsay Sedation Scale score consistent with mild-to-moderate sedation corresponded to Bispectral Index scores of 34 (general anesthesia) to 98 (fully awake), whereas a modified Ramsay Sedation Scale score consistent with deep sedation corresponded to Bispectral Index scores of 40 to 98. Areas under receiver operating characteristic curves demonstrated moderate (0.83 to 0.86) discriminatory power at all modified Ramsay Sedation Scale thresholds, with the exception of a modified Ramsay Sedation Scale score of 7 or less, which demonstrated high discriminatory power (0.95). A Bispectral Index score of greater than 83 reliably excluded general anesthesia, and a Bispectral Index score of 70 or less reliably identified general anesthesia.

CONCLUSION

Bispectral index monitoring reliably predicted patients undergoing procedural sedation and analgesia who were sedated to the point of general anesthesia from those with lesser degrees of sedation but did not discriminate mild-to-moderate sedation or moderate-to-deep sedation, as measured by the Ramsay Sedation Scale score for the patients undergoing procedural sedation and analgesia in our ED.

The timing of electroconvulsive therapy and bispectral index after anesthesia induction using different drugs does not affect seizure duration

STUDY OBJECTIVE

To determine the association between bispectral index (BIS) and seizure duration obtained by electroconvulsive therapy (ECT) administered sooner or later after anesthetic induction.

DESIGN

Prospective, randomized, crossover study.

SETTING

University-affiliated medical center.

PATIENTS

Nine ASA physical status I, II, and III patients undergoing a total of 31 ECTs.

INTERVENTIONS

ECT was administered soon (<210 sec) or later (between 210 sec and 360 sec) after anesthetic induction. In each individual patient, drug regimens and ECT machine settings were identical.

MEASUREMENTS

BIS immediately before the start of the ECT and the duration of the EEG seizure were recorded, as well as the time period between loss of consciousness and ECT administration.

MAIN RESULTS

There was no relationship between BIS level and seizure duration. Moreover, seizure duration was not dependent on the time of ECT administration in the time window between one and 6 minutes after loss of consciousness.

CONCLUSION

The hypnotic drug effect measured by the BIS is not correlated to the seizure duration obtained by ECT.

The use of methohexital during neonatal cardioversion

We report on the use of methohexital during elective neonatal direct current cardioversion. In contrast with the available data on cardiac management in neonates with supraventricular tachycardia and the guidelines on anaesthetic management during cardioversion in adults, data on anaesthetic management in neonates are still lacking. Methohexital might be an option for procedural sedation and anaesthesia during elective cardioversion in neonates.

Assessment of the postoperative discomfort of intra-auricularly hypophysectomized rats

Rats subjected to hypophysectomy make up one of the largest groups of experimental animals in Europe, since there is a legal demand for batch testing of industrially produced growth hormones. To describe the clinical performance of rats having undergone hypophysectomy, animals were examined postoperatively by monitoring behaviour, body temperature and food intake. Behavioural changes were observed in rats that had only been anaesthetized, as well as in sham-operated rats, while no behavioural deviations could be shown in hypophysectomized rats. On the first day after surgery all rats had declining body temperature and food intake; and this change was not reversed by treatment with carprofen, buprenorphine or oxytetracycline. The mortality rate in rats treated with buprenorphine was increased, as was the mortality rate in rats hypophysectomized when weighing more than 100 g. As there seemed to be no differences whether methohexital or a combination of fentanyl, fluanison and midazolam was used, the latter anaesthesia is recommended due to its analgesic potential. For post-surgical analgesic treatment, carprofen is recommended rather than buprenorphine. At best, the use of hypophysectomized rats should be replaced in industrial batch testing by an existing in vitro method.

Effects of combined methohexitone-remifentanil anaesthesia in electroconvulsive therapy

BACKGROUND

Methohexitone is widely used to provide anaesthesia for patients undergoing electroconvulstive therapy (ECT). Short seizure duration, high blood pressures (BP) and heart rates (HR) are usual in elderly patients. In this study, elderly patients undergoing ECT received low dose methohexitone with remifentanil or methohexitone alone and motor seizure duration, haemodynamic response and recovery time were compared.

METHODS

Ten patients, of mean age 74.3 years, were enrolled in this double-blind, randomised crossover trial, receiving a total of 38 ECTs. Each patient was given the following two i.v. regimens in random order: A) methohexitone 0.5 mg kg(-1) combined with remifentanil 1.0 microg kg(-1) and B) methohexitone 0.75 mg kg(-1). Additional methohexitone was given, if needed, until loss of consciousness, and then suxamethonium 1.0 mg kg(-1) for muscular paralysis.

RESULTS

Mean motor seizure duration was significantly longer with methohexitone-remifentanil (37.6 s (SD 12.0)) than with methohexitone alone (27.1 (SD11.5)) (P=0.0009). Recovery time, time to spontaneous breathing, peak postictal changes in BP and HR were similar with both regimens.

CONCLUSION

A reduced dose of methohexitone combined with remifentanil allows prolonged duration of motor seizures in ECT. We conclude that low dose methohexitone combined with a short-acting opioid is a reasonable alternative for elderly patients undergoing ECT, and for other patients with short seizure duration.

Post-ECT agitation and plasma lactate concentrations

This prospective study evaluated the hypothesis that emergence agitation after electroconvulsive therapy (ECT) could be caused by lactate-induced panic secondary to insufficient neuromuscular blockade. Plasma lactate levels were measured before and after 245 consecutive ECT sessions in 37 patients monitored for evidence of post-ECT agitation. ECT was administered using a brief-pulse, rectangular, constant-current device through bilaterally placed electrodes under general anesthesia and neuromuscular blockade. Agitation was observed in 7% of all ECT sessions. No significant difference could be found in pre-ECT lactate levels. However, mean post-ECT lactate levels in agitated sessions were significantly greater than those in nonagitated sessions (4.77 versus 2.54 mmol/l, p < 0.05). An increase (+27%) in the pre-ECT succinylcholine dose for those patients who previously had repeated post-ECT agitation resulted in cessation of post-ECT agitation and return of the formerly high post-ECT lactate levels to normal (1.61 versus 2.07 mmol/l). Although the number of patients who had post-ECT agitation was small, the data support the hypothesis that post-ECT agitation might be a manifestation of lactate-induced panic.

Proprioception more impaired distally than proximally in subjects with hemispheric dysfunction

Holmes noted that with hemispheric injuries proprioceptive disturbances were more marked in the distal than proximal limb segments and proposed that this difference was related to the size of cortical sensory representations. An alternative hypothesis is that sensation from distal segments projects to the contralateral hemisphere and sensation from proximal segments projects to both hemispheres. Selective hemispheric anesthesia was used to test these alternative hypotheses and revealed a decrement in distal but not proximal proprioception with hemispheric anesthesia, thereby supporting the bilateral projection hypothesis.

Acute detoxification of opioid-addicted patients with naloxone during propofol or methohexital anesthesia: a comparison of withdrawal symptoms, neuroendocrine, metabolic, and cardiovascular patterns

OBJECTIVE

Mu-Opioid receptor blockade during general anesthesia is a new treatment for detoxification of opioid addicted patients. We assessed catecholamine plasma concentrations, oxygen consumption, cardiovascular variables, and withdrawal symptoms after naloxone and tested the hypothesis that variables are influenced by the anesthetic administered during detoxification.

DESIGN

Prospective randomized clinical study.

SETTING

Intensive care unit of a university hospital and psychiatric ward.

PATIENTS

Twenty-five mono-opioid addicted patients with mild to moderate systemic disease (ASA II classification) in a methadone substitution program.

INTERVENTION

General anesthesia with either propofol (129+/-7 microg x kg(-1) x min(-1), mean +/- SEM) or methohexital (74+/-14 microg x kg(-1). min(-1)), mu-opioid receptor blockade by naloxone in a stepwise fashion (increasing doses of 0.4 mg, 0.8 mg, 1.6 mg, 3.2 mg, and 6.4 mg at 15 min intervals followed by 0.8 mg x hr(-1) for 24 hrs) and naltrexone 50 mg x day(-1) orally for > or =4 wks. Clonidine was started 180 mins after the first naloxone dose and its infusion rate was individually adjusted to mitigate withdrawal symptoms during weaning and after extubation.

MEASUREMENTS AND MAIN RESULTS

During propofol and methohexital anesthesia, naloxone induced a 30-fold increase in epinephrine and a significant three-fold increase in norepinephrine plasma concentrations without a significant difference between groups. This increase in catecholamine plasma concentrations was associated with increased oxygen consumption and marked cardiovascular stimulation with both anesthetics, as shown by increased cardiac index, heart rate, and systolic atrial pressure whereas diastolic pressure remained unchanged. Patients receiving propofol could be extubated significantly earlier after discontinuation of the anesthetics. Although the maximum degree of withdrawal symptoms (Short Opioid Withdrawal Scale) on the day after detoxification was similar with both anesthetics, subsequent withdrawal symptoms decreased significantly more rapidly after propofol anesthesia.

CONCLUSIONS

Naloxone treatment, in opioid-addicted patients, induced a marked increase in catecholamine plasma concentrations, metabolism, and cardiovascular stimulation during anesthesia with both propofol and methohexital. Although both anesthetics appear suitable for detoxification treatment, the use of propofol is associated with earlier extubation and, surprisingly, a shortened period of long-term withdrawal symptoms during detoxification.

Pharmacological activation

Despite the disparate results in clinical studies a few conclusions can be made. Pharmacologic activation during ECoG serves a minor role in determining the limits of a cortical excision during surgical treatment for intractable partial epilepsy. The extensive preoperative evaluation including long-term EEG monitoring to assess the electroclinical correlation and MRI are of primary importance. There is sufficient information at some epilepsy centers demonstrating a putative beneficial effect of ECoG that its continued use can be justified. Pharmacologic activation of epileptiform discharges is never preferred to spontaneous alterations occurring in the pre-excision ECoG. It would seem reasonable to consider pharmacologic activation at the time of the pre-excision ECoG if no discharges are present. Further studies will be needed to decide on the 'drug of choice', but for now methohexital would be most reasonable given the enormous amount of information regarding its induction properties. One must keep in mind the clear limitations associated with the use of these drugs especially the possibility of 'misleading' informations as documented by Fiol et al. (1990). The use of post-excision ECoG in general is sufficiently dubious that the practice of pharmacologic activation during this recording cannot be recommended. Perhaps the most reasonable view of pharmacologic activation is the position articulated by our Dr. Norman So (1995): 'There are many who advocate the injection of a short-acting barbiturate like methohexital to activate spiking during ECoG, but given the difficulty already encountered in interpreting the spontaneous ECoG it seems foolhardy to complicate the picture with potentially non-specific drug effects'.

[The comparison of ketamine with methohexital and thiopental in the intraoperative EEG in drug-resistant epilepsy]

The acute (ECoG) was examined in 291 patients with intractable epilepsy, without structural brain lesion--from 1971 to 1997. Temporal lobectomy was performed in 198 cases and extratemporal (frontal, parietal or occipital) in remaining 93 cases to achieve seizure control. Epileptic foci was activated during acute ECoG by i.v. administration of ketamine (154 cases) or short-acting barbiturates--methohexital (110 cases) and thiopental (27 cases).

RESULTS

Ketamine significantly more often caused ECoG identified electrographic seizures than methohexital: p = 0, 00001 or thiopental, which in no cases resulted in seizures. Also electrographic seizures occurred more frequently after administration of ketamine in patients with the extratemporal seizure focus localisation in comparison with temporal focus (p < 0.05). Electrographic seizures provoked after administration of ketamine improved the localisation of the area to be resected, more often in extratemporal epileptic foci.

CONCLUSIONS

The results of our investigations indicate that ketamine more effectively activated epileptic focus than short-acting barbiturates.

Profound increase in epinephrine concentration in plasma and cardiovascular stimulation after mu-opioid receptor blockade in opioid-addicted patients during barbiturate-induced anesthesia for acute detoxification

BACKGROUND

Acute displacement of opioids from their receptors by administration of large doses of opioid antagonists during general anesthesia is a new approach for detoxification of patients addicted to opioids. The authors tested the hypothesis that mu-opioid receptor blockade by naloxone induces cardiovascular stimulation mediated by the sympathoadrenal system.

METHODS

Heart rate, cardiac index, and intravascular pressures were measured in 10 patients addicted to opioids (drug history; mean +/- SD, 71 +/- 51 months) during a program of methadone substitution (96 +/- 57 mg/day). Cardiovascular variables and concentrations of catecholamine in plasma were measured in the awake state, during methohexital-induced anesthesia (dose, 74 +/- 44 microg x kg(-1) x min(-1)) before administration of naloxone, and repeatedly during the first 3 h of mu-opioid receptor blockade. Naloxone was administered initially in an intravenous dose of 0.4 mg, followed by incremental bolus doses (0.8, 1.6, 3.2, and 6.4 mg) at 15-min intervals until a total dose of 12.4 mg had been administered within 60 min; administration was then continued by infusion (0.8 mg/h).

RESULTS

Concentration of epinephrine in plasma increased 30-fold (15 +/- 9 to 458 +/- 304 pg/ml), whereas concentration of norepinephrine in plasma only increased to a minor extent (76 +/- 44 to 226 +/- 58 pg/ml, P < 0.05). Cardiac index increased by 74% (2.7 +/- 0.41 to 4.7 +/- 1.7 min(-1) x m(-2)), because of increases in heart rate (89 +/- 16 to 108 +/- 17 beats/min) and stroke volume (+44%), reaching maximum 45 min after the initial injection of naloxone. In parallel, systemic vascular resistance index decreased (-40%). Systolic arterial pressure significantly increased (113 +/- 16 to 138 +/- 16 mmHg), whereas diastolic arterial pressure did not change.

CONCLUSIONS

Despite barbiturate-induced anesthesia, acute mu-opioid receptor blockade in patients addicted to opioids induces profound epinephrine release and cardiovascular stimulation. These data suggest that long-term opioid receptor stimulation changes sympathoadrenal and cardiovascular function, which is acutely unmasked by mu-opioid receptor blockade. Because of the attendant cardiovascular stimulation, acute detoxification using naloxone should be performed by trained anesthesiologists or intensivists.

Localisation of epileptic foci with electric, magnetic and combined electromagnetic models

We compare the localisation of epileptic foci by means of (1) EEG, (2) magnetoencephalography (MEG) and (3) combined EEG/MEG data in a group of patients suffering from pharmaco-resistant focal epilepsy. Individual epileptic events were localised by means of a moving dipole model in a 4-shell spherical head approximation. A patient's epileptic activity was summarised by calculating the spatial density distribution (DD) of all localised events, and the centre of gravity of DD was considered the most likely locus of seizure generation. To verify these loci a subgroup of 6 patients was selected, in which seizures could be related to a clearly identifiable lesion in MRI. On average, the combined EEG/MEG approach resulted in the smallest error (1.8 cm distance between calculated locus and the nearest lesion border); using only MEG yielded the largest error (2.4 cm), while EEG resulted in an intermediate value (2.2 cm). In the individual patients, EEG/MEG would also rank intermediate, but never worst. In summary, combining EEG/MEG appears to be a more robust approach to localisation than using only EEG or only MEG. Finally, we also report on the use of the barbiturate methohexital as a safe method of increasing the number of spike events during an EEG/MEG recording session.

7-Nitro indazole enhances methohexital anesthesia

7-nitro indazole, a selective inhibitor of the neuronal nitric oxide (NO) synthase dose-dependently prolongs the duration of methohexital narcosis in the rat. This effect can be antagonized stereoselectively by the NO-synthase substrate l-arginine (l-Arg). The results support the assumption that the potentiation of the anesthetic state by NO-synthase inhibitors is due to a specific effect on brain NO-synthase and a disruption of synaptic NO signalling pathways. These results are also in accordance with predictions that follow from recent hypotheses proposing that a modification of the NMDA receptor function is the final common pathway of anesthetic action.

Propofol and methohexital as anesthetic agents for electroconvulsive therapy (ECT): a comparison of seizure-quality measures and vital signs

In a randomized crossover study, the influence of the anesthetics methohexital and propofol on EEG seizure parameters, seizure-quality measures, vital signs, and oxygen saturation (SpO2) and end-tidal carbon dioxide tension (ETCO2) was investigated; 146 treatments of 31 patients were analyzed. Significant differences were observed between agents for mean postictal pulse and blood pressure values. With methohexital, there was a clear postictal increase of mean blood pressure from 126/78 mm Hg to 161/102 mm Hg, whereas there was no increase with propofol (p = 0.00), and with methohexital, a postictal increase of the mean pulse rate from 81 to 90 beats/min and a slight decrease with propofol (79 to 78 beats/min). There were no differences in the SpO2 and ETCO2. The mean seizure duration for unilateral treatments was significantly longer with methohexital (52.7 s) compared with propofol (34.1 s; p = 0.000), but there was no difference for the seizure-quality measures: postictal suppression index (propofol 79.7%, methohexital 77.4%) and mean integrated amplitude (30.2/31.8) were the same for both anesthetic agents. The results show that differences in seizure duration are unrelated to seizure-quality measures.

Anosognosia and confabulation during the Wada test

Feinberg et al. proposed that right-hemisphere-damaged stroke patients with anosognosia for hemiplegia (AHP) confabulate seeing stimuli on the left side but those without AHP admit to having inadequate visual information. This study examines the relationship between AHP and confabulation using selective anesthesia of the cerebral hemispheres. Seventeen patients with intractable epilepsy were tested during intracarotid methohexital infusion. For half of the trials, subjects were stimulated on their paretic hand with a material (sandpaper, metal, or cloth), and for the remaining trials they were not stimulated. The subjects were trained to use a pointing response to indicate if they been stimulated and the type of material they had felt. Admission of uncertainty was defined as pointing to a question mark. Confabulation was defined as any material response to a no-touch trial. During anesthesia of either hemisphere, subjects with and without AHP confabulated responses. The AHP and non-AHP groups did not differ in admission of uncertainty. Our results support the postulate that confabulation and AHP are independent disorders, and therefore confabulation cannot fully account for AHP.

Use of methohexital for elective intubation in neonates

The effectiveness and safety of a short acting barbiturate, methohexital, was assessed for its use at the time of elective intubation in 18 newborn infants with severe respiratory or cardiac conditions. Evaluation included the speed of action and the degree of relaxation, sedation, and sleep in the first five minutes after administration. All newborn infants were intubated in a fully relaxed and somnolent state. In most infants recovery was completed within five minutes. A slight to moderate oxygen saturation drop was observed during the period of intubation, especially in patients with cyanotic heart disease. The side effects of the drug were twitching and a slight drop in blood pressure. In conclusion, methohexital seems to be a useful drug for short term anaesthesia in neonates, during which, short procedures like elective intubation can be safely performed.

ECT for the treatment of intractable mania in two prepubertal male children

We provide case reports of the successful use of electroconvulsive therapy (ECT) for intractable mania in two prepubertal male children. Both children responded well to ECT without significant complications. The report focuses in particular on the procedure and technique of doing ECT in this patient population.

Ketamine anesthesia in electroconvulsive therapy

The use of ketamine anesthesia in electroconvulsive therapy (ECT) has been limited by its effects on blood pressure and concerns about untoward psychological reactions. However, because its effect on seizures is presumably less than that of methohexital, ketamine is listed as an alternative method to prolong seizure length. In this case series, 10 patients were given ketamine anesthesia during ECT. Whereas blood pressures were elevated above those seen with methohexital, seizure lengths actually decreased nonsignificantly with ketamine. There were no adverse psychological reactions noted with ketamine, which was generally well tolerated. It is concluded that ketamine anesthesia with the doses used in this series is unlikely to be associated with longer seizures in ECT. However, for theoretical reasons discussed, ketamine may be worth studying further in ECT.

Total i.v. anaesthesia for transcranial magnetic evoked potential spinal cord monitoring

Continuous intraoperative monitoring of transcranial magnetic motor evoked potentials (TcMMEP) can warn the surgeon of motor tract damage more effectively than somatosensory evoked potentials. As a non-invasive technique it is especially useful during post-traumatic internal fixation and is applicable whatever the level of the spinal cord at risk. Inhalation and many i.v. anaesthetics block the single pulse TcMMEP but a total i.v. anaesthetic regimen based on methohexitone, alfentanil and ketamine was effective in seven patients undergoing post-traumatic internal fixation. Consistent TcMMEP of 100-1000 mcV were obtained in all patients, with a latency change of only 2 ms above preoperative values. Good cardiovascular stability was maintained during operation.

Landau-Kleffner syndrome. Treatment with subpial intracortical transection

Landau-Kleffner syndrome (LKS) is an acquired epileptic aphasia occurring in childhood and associated with a generally poor prognosis for recovery of speech. It is thought to be the result of an epileptogenic lesion arising in speech cortex during a critical period of development. Utilizing a new surgical technique designed to eliminate the capacity of cortical tissue to generate seizures while preserving the normal cortical physiological function, we have treated 14 children with aphasia, seizures and a severely abnormal EEG by multiple subpial transection of the epileptogenic cortex. Seven of the 14 patients (50%) have recovered age-appropriate speech, are in regular classes in school and no longer require speech therapy. Four of the 14 (29%) have shown marked improvement, are speaking and understanding verbal instruction but are still receiving speech therapy. Thus, 11 of the 14 (79%), none of whom had used language to communicate for at least 2 years, are now speaking--a rate of sustained improvement considered unusual in this disorder. This study documents the value of a treatment modality not previously used in LKS. Success depends on selection of cases having severe epileptogenic abnormality that can be demonstrated to be unilateral in origin despite a bilateral electrographic manifestation.