Pirjo H. Manninen

Monitoring electrophysiologic function during carotid endarterectomy: a comparison of somatosensory evoked potentials and conventional electroencephalogram.

There is no consensus as to the most appropriate monitor for detecting ischemia during carotid endarterectomy. Accordingly, simultaneous 16-channel continuous electroencephalogram (EEG) and somatosensory evoked potential (SSEP) monitoring were performed in 64 normocapnic patients undergoing carotid endarterectomy and anesthetized with isoflurane or halothane-nitrous oxide (supplemented with fentanyl). Recordings were obtained before, during, and for 15 min after cross-clamping of the internal carotid artery. Internal shunt was not used in any patient, regardless of EEG and SSEP changes. Significant amplitude reduction in the cortical component of the primary negative peak (greater than 50%) in SSEP occurred in 6 patients, and an increase in central conduction time (CCT) (greater than 1 ms) occurred in 5 patients. Major EEG changes occurred in 6 patients, 4 of whom also had SSEP changes. Two patients had transient neurologic deficits postoperatively, with both having SSEP changes (amplitude reduction greater than 50%), whereas one had EEG changes. Based on these observations, the relative sensitivity and specificity for EEG and SSEP (amplitude reduction greater than 50%) in detecting postoperative neurologic deficits were 50% and 92% for EEG and 100% and 94% for SSEP, respectively, differences that were not statistically significant. Regarding SSEP, the use of latency change (CCT) as a criterion was associated with a sensitivity of 0% (P = 0.046 from sensitivity of amplitude) and a specificity of 87% (P = 0.17 from specificity of amplitude).(ABSTRACT TRUNCATED AT 250 WORDS)

Awake craniotomy for removal of intracranial tumor : Considerations for early discharge

We retrospectively reviewed the anesthetic management, complications, and discharge time of 241 patients undergoing awake craniotomy for removal of intracranial tumor to determine the feasibility of early discharge. The results were analyzed by using univariate analysis of variance and multiple logistic regression. The median length of stay for inpatients was 4 days. Fifteen patients (6%) were discharged 6 h after surgery and 76 patients (31%) were discharged on the next day. Anesthesia was provided by using local infiltration supplemented with neurolept anesthesia consisting of midazolam, fentanyl, and propofol. There was no significant difference in the total amount of sedation required. Overall, anesthetic complications were minimal. One patient (0.4%) required conversion to general anesthesia and one patient developed a venous air embolus. Fifteen patients (6%) had self-limiting intraoperative seizures that were short-lived. Of the 16 patients scheduled for ambulatory surgery, there was one readmission and one unanticipated admission. It may be feasible to discharge patients on the same or the next day after awake craniotomy for removal of intracranial tumor. However, caution is advised and patient selection must be stringent with regards to the preoperative functional status of the patient, tumor depth, surrounding edema, patient support at home, and ease of access to hospital for readmission. IMPLICATIONS It may be feasible to perform awake craniotomies for removal of intracranial tumor as an ambulatory procedure; however, caution is advised. Patient selection must be stringent with respect to the patient’s preoperative functional status, tumor depth, surrounding edema, patient support at home, and ease of access to hospital for readmission.

LONG-TERM COGNITIVE AND SOCIAL SEQUELAE OF GENERAL VERSUS REGIONAL ANESTHESIA DURING ARTHROPLASTY IN THE ELDERLY

This study compared the effects of general and regional anesthesia on cognitive and psychosocial functioning in elderly persons. Sixty-four patients between 60 and 86 yr of age undergoing knee arthroplasty were randomly assigned to receive either general or regional anesthesia. A battery of psychometric tests, including the Satz-Mogel form of the Wechsler Adult Intelligence Scale-Revised, the Wechsler Memory Scale-Revised and the Sickness Impact Profile, and various neuropsychological measures were administered by a blinded observer just before surgery and again 3 months later. Analyses of covariance revealed improvements in most measures that were equivalent between groups. The results indicated that there were no cognitive or psychosocial effects of general or regional anesthesia after 3 months in elderly persons undergoing knee arthroplasty. In this patient population, general anesthesia poses no more risk to long-term mental function than regional anesthesia.

Patient satisfaction with awake craniotomy for tumor surgery: a comparison of remifentanil and fentanyl in conjunction with propofol.

In this study we compared the effectiveness of the use of remifentanil to fentanyl in conjunction with propofol in providing conscious sedation for awake craniotomy for tumor surgery and to assess patient satisfaction with both techniques. The ability to maintain appropriate levels of sedation, adequate analgesia, and hemodynamic stability was assessed in 50 patients randomized to receive either fentanyl or remifentanil. All complications were documented. Patients were interviewed at 1 h, 4 h, and 24 h after surgery to note their recall of procedure and pain and their overall satisfaction. There were no differences in sedation and pain scores or in hemodynamic and respiratory variables between the two groups. The incidence of intraoperative complications was not different (fentanyl, 14; remifentanil, 16). Respiratory complications occurred in 9 (18%) patients (fentanyl 6, remifentanil 3). The recall and satisfaction scores were not different; 93% of all patients were completely satisfied at all interview times. The use of remifentanil infusion in conjunction with propofol is a good alternative to fentanyl and propofol for conscious sedation for the awake craniotomy and these techniques are both well accepted by the patient.

Early postoperative complications following neurosurgical procedures.

PurposeTo assess the incidence and characteristics of early postoperative complications in patients following neurosurgical procedures.MethodsAll patients undergoing neurosurgery during a four month period were followed postoperatively for up to four hours in the post anesthetic care unit or intensive care unit. Patient information and all complications were documented by the investigators on a standardized form. Complications were classified as respiratory, cardiovascular, nausea and vomiting, shivering and other. Risk factors analyzed for the occurrence of complications included age, sex, ASA status, type of surgery, elective or emergency surgery and postoperative placement.ResultsFour hundred eighty six adult patients were followed, but in 55 patients the trachea remained intubated during the four hour study period and they were eliminated from the analysis of postoperative complications. At least one complication occurred in 54.5% of the remaining 431 patients. Respiratory problems occurred in 2.8%, trauma to the airway in 4.4%, cardiovascular complications in 6.7%, neurological in 5.7% and nausea and/or vomiting in 38%. The highest incidence of patients with complications was during spine (65%) and vascular (66%) surgery, compared with tumour (47%) and other (43%) surgery, P < 0.05. Other risk factors included age < 70 yr for nausea and vomiting (P < 0.02), and elective surgery for spine and vascular surgery (P < 0.001 ).ConclusionThere was a high incidence of early postoperative complications in neurosurgical patients. The most common problem was nausea and vomiting especially in the younger patient undergoing elective spine surgery.RésuméObjectifÉvaluer les caractéristiques et l’incidence de complications postopératoires précoces chez des patients qui ont subi une intervention neurochirurgicale.MéthodePendant quatre mois, tous les patients qui avaient subi une neurochirurgie ont été suivis, pendant une période pouvant aller jusqu’à quatre heures, à la salle de réveil ou à l’unité des soins intensifs. Les chercheurs ont noté sur un formulaire standardisé les informations recueillies auprès du patient et toutes les complications. Ces dernières ont été classées en complications respiratoires, cardiovasculaires, nausées et vomissements, frissons et autres. Les facteurs de risques analysés selon la survenue des complications comprenaient l’âge, le sexe, l’état ASA, le type de chirurgie, l’aspect prévisible ou non de la chirurgie et le placement postopératoire.RésultatsQuatre cent quatre-vingt six patients adultes ont été suivis, mais on a exclu 55 patients de l’analyse des complications postopératoires puisqu’ils ont eu besoin d’intubationpendant les quatre heures de l’expérience. Une complication au moins est survenue chez 54,5 % des 431 autres patients. Des complications respiratoires sont survenues chez 2,8 % des patients, cardiovasculaires chez 6,7 %, neurologiques chez 5,7 %; un traumatisme des voies aériennes chez 4,4 % et des nausées et/ou des vomissements chez 38 %. La plus forte incidence de complications a été enregistrée pendant la chirurgie rachidienne (65 %) et vasculaire (66 %), comparativement à la chirurgie pour une tumeur (47 %) ou à d’autres chirurgies (43 %),P < 0,05. Les autres facteurs de risque comprenaient l’âge < 70 ans pour les nausées et les vomissements (P < 0,02) et le caractère non urgent de la chirurgie rachidienne et vasculaire (P < 0,001 ).ConclusionIl y a eu une forte incidence de complications postopératoires précoces chez les patients admis en neurochirurgie. Les nausées et les vomissements se sont présentés le plus souvent et surtout chez les jeunes patients subissant une chirurgie rachidienne.

The effect of high-dose mannitol on serum and urine electrolytes and osmolality in neurosurgical patients.

The effect of mannitol on serum and urine electrolytes and osmolality was investigated intraoperatively in neurosurgical patients. Patients in Group A (n = 7) received 1 gm·kg-1 of 20 per cent mannitol (“low”-dose) and in Group B, (n = 7) 2 gm·kg-1 (“high”-dose). There was a significant decrease in serum sodium and bicarbonate, and a significant increase in serum osmolality in both groups after mannitol administration. The decrease in serum sodium and the increase in serum osmolality were significantly greater in patients receiving the larger dose of mannitol. The infusion of low-dose mannitol resulted in a slight decrease in serum potassium, in contrast, after highdose mannitol there was a significant rise in serum potassium reaching a maximum mean increase of 1 .5 mmolľ1-1. Urine electrolyte concentration and osmolality showed a similar decrease in both groups. The significant changes that occurred with the administration of mannitol were of short duration in these patients with normal cardiac and renal function. The clinically most important change is the increase in serum potassium with high-dose manitol. The exact mechanism of this increase remains unclear.RésuméOn a examiné ľeffet du mannitol sur les électrolytes et ľosmotalité sériques et urinaires en période intraopératoire chez les patients neurochirurgicaux. Les patients du groupe A (n = 7) ont reçu 1 g·kg-1 de 20 pour cent de mannitol (“faible” dose) et ceux du groupe B (n = 7), ont reçu 2 g·kg-1 (dose “élevée”). Une diminution significative du sodium et du bicarbonnate sêrique, et une augmentation significative de ľosmolalité sêrique s’est produite dans les deux groupes après ľadministration du mannitol. La diminution du sodium sêrique et ľaugmentation de V osmolalité sêrique étaient beaucoup plus élevées chez les patients recevant une dose importante de mannitol. Ľinfusion ďune faible dose de mannitol a entraîné une légère diminution du potassium sêrique. Par contre, après ľadministration ďune dose élevée de mannitol, le potassium sêrique a augmenté de façon significative atteignant une augmentation maximum moyenne de 1.5 mmol·L-1. La concentration électrolytique et ľosmolalité urinaire ont démontré une diminution semblable dans les deux groupes. Les changements significatifs qui se sont produits avec ľadministration de mannitol étaient de courte durée chez les patients ayant une fonction cardiaque et une fonction rénale normales. Le changement clinique le plus important est ľaugmentation du potassium sêrique en présence ďune dose élevée de mannitol. On ne comprend pas encore clairement le mécanisme exact de cette augmentation.

Comparison of fentanyl, sufentanil and alfentanil during awake craniotomy for epilepsy

Neurolept anaesthesia is used during awake craniotomy for epilepsy surgery. This study compares analgesia, sedation and the side effects of the newer opioids sufentanil and alfentanil, with those of fentanyl in patients undergoing awake craniotomy. Thirty patients were randomized into three groups, each received droperidol, dimenhydrinate and the chosen opioid as a bolus followed by an infusion. The opioid doses used were fentanyl 0.75 μg · kg−1 plus 0.01 μg · kg−1 · min−1; sufentanil 0.075 μg · kg−1 plus 0.0015 μg · kg−1 · min−1, and alfentanil 7.5 μg · kg−1 plus 0.5 μg · kg−1 · min−1. There were no differences in the requirements for droperidol, dimenhydrinate or in the incidence of complications among the three groups. The total doses of the opioids required were fentanyl 4.9 ±1.3 μg · kg−1, sufentanil 0.6 ±0.2 μg · kg−1 and alfentanil 149 ±36 μg · kg−1. Two patients became uncooperative requiring general anaesthesia. The conditions for surgery, electrocorticography and for stimulation testing were satisfactory in all other patients. We conclude that the newer opioids did not offer any benefit over fentanyl.RésuméLe traitement chirurgical de l’épilepsie par craniotomie se fait souvent à l’état vigile sous neuroleptanalgésie. Cette étude vise à comparer l’analgésie, la sédation et les effets secondaires des nouveaux morphiniques sulfentanil et alfentanil avec le fentanyl chez des malades en cours de cranitomie vigile. Trente patients sont distribués au hasard en trois groupes, chacun recevant dropéridol, dimenhydrinate et un des morphiniques en bolus suivi d’un perfusion. La posologie est pour le fentanyl de 0,75 μg · kg−1 et par la suite de 0,01 μg · kg−1 · min−1; pour le sufentanil de 0,075 μg · kg−1 et par la suite de 0,0015 μg · kg−1 · min−1 et pour l’alfentanil de 7,5 μg · kg−1 et par la suite de 0,5 μg · kg−1 · min−1. Les besoins de dropéridol et de dimenhydrinate et l’incidence de complication ont été les mêmes pour les trois groupes. La dose totale est pour le fentanyl 4,9 ±1,3 μg · kg−1, Ie sufentanil, 0,6 ±0,2 μg · kg−1 et l’alfentanil de 149 ±36 μg · kg−1. Deux malades qui ont cessé de collaborer, doivent être anesthésiés. Les conditions de la chirurgie, de l’électrocorticographie et des tests de stimulation sont satisfaisantes pour tous les autres patients. Nous concluons que les nouveaux morphiniques n’offrent aucun avantage sur le fentanyl.

Evoked potential monitoring during posterior fossa aneurysm surgery : a comparison of two modalities

The purpose of this study was to compare and assess the ability of two different evoked potential (EP) modalities, median nerve somatosensory evoked potentials (SSEP) and brainstem auditory evoked potentials (BAEP) in monitoring for cerebral ischaemia and in predicting neurological outcome during posterior fossa aneurysm surgery. During 70 procedures, patients were monitored with both SSEP and BAEP Temporary occlusion of an artery was used in 52 patients and permanent occlusion in 21 patients. A change was defined as a greater than 50% decrease in amplitude and/or an increase in latency greater than 1 msec of the N20 (cortical waveform) for SSEP monitoring and of the fifth peak for BAEP monitoring. Neurological assessment of the patient was performed immediately on emergence, after 24 hr and at the time of discharge. In total, 14 patients had an SSEP change which predicted a neurological deficit in eight patients (57%). Ten patients had a change in BAEP; six had a neurological deficit (60%). Five patients had a change in both, two had a deficit (40%). The incidence of false negative results (a neurological deficit but no EP change) for both modalities was 20% (SSEP 47%, BAEP 60%). The incidence of false positive results (an EP change but no deficit) was 13% overall (SSEP 11%, BAEP 7%). All patients who had a permanent EP change developed a neurological deficit. We did not find a difference in the ability of SSEP compared with BAEP in predicting neurological deficits but, using both modalities, the incidence of false negative results was decreased. In conclusion, dual modality monitoring should be used whenever possible as neither modality alone was better than the other in detecting cerebral ischaemia and in predicting neurological deficits.RésuméCette étude vise à évaluer et comparer la capacité de deux méthodes de mesure des potentiels évoqués (EP) pour le monitorage de l’ischémie cérébrale et pour la prédiction du pronostic neurologique pendant la chirurgie de la fosse postérieure: les potentiels évoqués somatosensoriels du nerf médian (SSEP) et les potentiels évoqués auditifs du tronc cérébral. Au cours de 70 interventions, on monitorise à la fois les SSEP et les BAEP. L’occlusion temporaire d’une artère est réalisée chez 52 patients et l’occlusion permanente chez 21 patients. Un changement est défini comme une baisse de l’amplitude de plus de 50% avec ou sans une augmentation de la latence de 1 msec de N20 (forme d’onde corticale) pour le moniteur de SSEP et du cinquième pic pour le moniteur de BAEP. Une évaluation neurologique est faite dès le réveil, après 24 h et au moment du congé. Au total, 14 patients ont montré des SSEP altérés qui ont permis la prédiction d’un déficit neurologique chez huit patients (57%). Dix patients ont montré des altérations de BAEP; six avaient un déficit neurologique (60%). Cinq patients avaient des altérations des deux; deux patients avaient un déficit (40%). L’incidence de faux négatifs (un de’ficit neurologique sans alteration dEP) pour les deux méthodes était de 13% (SSEP 11% BAEP 7%). Tous les patients avec un changement permanent de l’EP ont eu un déficit neurologique. Nous n’avons pas trouvé de différence entre la capacité des SSEP comparativement aux BAEP, pour la prédiction des déficits neurologiques, mais l’utilization concomitante des deux méthodes permet de diminuer l’incidence des faux négatifs. En conclusion, pour détecter l’ischémie cérébrale, comme une des méthodes seule est meilleure que l’autre, les deux méthodes devraient être associées lorsque possible.

Intraoperative localization of an epileptogenic focus with alfentanil and fentanyl

We evaluated the effectiveness of alfentanil and fentanyl in stimulating epileptogenic activity during surgery for intractable temporal lobe epilepsy under general anesthesia. Ten patients received a standardized anesthetic induction with IV fentanyl 5 mg/kg, propofol 3‐5 mg/kg, and atracurium 0.5 mg/kg. Maintenance was with isoflurane, 70% N2O/30% O2, and an atracurium infusion. After dural opening, droperidol 0.02 mg/kg was administered IV. Both inhaled anesthetics were discontinued and verified to be at 0 endtidal concentration before the study. Baseline electrocorticography over the surface of the temporal lobe and depth electrode recordings in the amygdala and hippocampus were obtained, followed by 10 min of recording before and after the IV administration of both alfentanil 50 mg/kg and fentanyl 10 mg/kg. Any changes in cardiovascular variables were documented. The number of interictal epileptiform spikes at the most active site for each patient was tabulated before and after the administration of each drug. Both alfentanil and fentanyl induced an increase in spike activity in all patients. Alfentanil was more potent, increasing the median number of spikes per epoch from 18 to 58, compared with fentanyl (20 to 42 spikes) (P , 0.05). Alfentanil had a shorter duration of action (4.9 6 1.3 min) compared with fentanyl (8.5 6 2 min) (P , 0.009). In nine patients, the most active site was the hippocampus or amygdala. There was a decrease in mean blood pressure, but only after the administration of alfentanil (P , 0.05). Two patients had electrographic evidence of seizure activity. These opioids can be used to assist in the localization of the epileptogenic focus during surgery. Implications: Both alfentanil and fentanyl activate epileptiform activity in patients with temporal lobe epilepsy. These opioids can be used to assist in the localization of the epileptogenic focus during surgery.

The effects of isoflurane and isoflurane-nitrous oxide anesthesia on brainstem auditory evoked potentials in humans.

Monitoring of brainstem auditory evoked potentials (BAEP) during neurological surgery can provide useful information. However, in order to interpret intraoperative BAEP changes, it is necessary to delineate the influence of anesthesia, including inhalation agents. In this study, we examined the influence of isoflurane and isoflurane-nitrous oxide anesthesia on BAEP in ten healthy volunteers during normothermic, normocapnic, and normotensive conditions. isoflurane significantly increased the latencies of peaks III, IV, and V at all end-tidal concentrations studied (1.0%, 1.5%, and 2.0%). Addition of 50% nitrous oxide did not influence these findings. The increase in latencies with isoflurane anesthesia, however, was nonlinear and appeared to plateau after 1.5%. We suggest that during isoflurane anesthesia, an intraoperative increase in peak V latency beyond 1.0 msec is best explained by factors other than direct effect of isoflurane.