Arlette Vandesteene

Effect of propofol on cerebral blood flow and metabolism in man.

Cerebral blood flow, cerebral oxygen consumption, lactate and glucose metabolism were measured in 13 patients during anaesthesia with nitrous oxide, oxygen and enflurane 0.5% and after 30 minutes infusion of propofol. The mean blood concentration of propofol was 4.06μg/ml. Cerebral blood flow decreased by 27.6% and cerebral vascular resistance by 51%. There were no changes in lactate and glucose metabolism. Cerebral oxygen consumption decreased by 18.25%. Changes in the electroencephalograph were related to the blood levels of propofol.

Combined positron emission tomography and magnetic resonance imaging for the planning of stereotactic brain biopsies in children: Experience in 9 cases

Because brain tumors can be histologically heterogeneous, stereotactic brain biopsies (SBB) may lead to inaccurate diagnosis or grading. Positron emission tomography (PET) has been used in pediatric neuro-oncology to help in the understanding and management of brain neoplasms. We combined PET and magnetic resonance (MR) imaging in the planning of SBB in 9 children (5 males and 4 females, aged 2–14 years) with infiltrative, ill-defined brain lesions. Tracers used for PET were 18F-2-fluoro-2-deoxy-D-glucose in 4 cases, 11C-methionine in 2 cases and both tracers in 3 cases. Biopsy targets were selected in hypermetabolic areas. PET-guided SBB provided accurate histological diagnosis in all patients and allowed a reduction of the number of trajectories in lesions located in functional areas. It also helped in better understanding and management of complex cases. This preliminary series suggests that combining PET and MR imaging in the planning of SBB in children (1) improves the diagnostic yield of SBB in infiltrative, ill-defined brain lesions, (2) makes it possible to reduce the sampling in high-risk/functional areas and (3) improves the quality of therapeutic management of pediatric brain tumors.

Stereotactic brain biopsy guided by positron emission tomography (PET) with [F-18]fluorodeoxyglucose and [C-11]methionine.

The aim of the present study was to compare the contribution of the labelled tracers [C-11]methionine (Met) and [F-18]-fluorodeoxyglucose (FDG) in positron emission tomography (PET)-guided stereotactic biopsy of non resectable brain lesions. Twenty-five patients underwent combined Met-PET-, FDG-PET- and computerized tomography (CT)- or magnetic resonance (MR)-guided stereotactic biopsy according to a previously described technique for stereotactic FDG-PET. Met-PET and FDG-PET images were analyzed to determine which tracer offers the best information to guide at least one stereotactic biopsy trajectory. Histological diagnosis was obtained in all patients (23 tumours and 2 non-tumorous lesions). All tumours had an area of abnormal Met uptake and were biopsied under PET-guidance. FDG uptake in the tumour was higher than in the grey matter and was used for target selection in 12 of 23 tumours. Eleven of them were located in the basal ganglia or the brainstem. Met was used for target selection in 11 of 23 tumours where there was no FDG uptake or where FDG uptake was equivalent to that of the grey matter. Ten of them were located in the cortex. Two nontumoral lesions had no Met uptake and were biopsied under CT- or MR-guidance only. Forty-three out of 53 stereotactic trajectories obtained in these 25 patients were based on PET-defined targets and had an area of abnormal Met uptake. These trajectories always yielded a diagnosis of tumour. Moreover, all tumorous trajectories had an area of abnormal Met uptake. Finally, all non-diagnostic trajectories (n = 4) were CT/MR-defined because there was no area of abnormal Met uptake. These results suggest that patients who can benefit the most from Met-PET guidance could be selected pre-operatively. In conclusion, this work shows that Met is a good alternative to FDG for target selection in PET-guided stereotactic brain biopsy.

Spinal and brain-stem SEPs and H reflex during enflurane anesthesia.

Whereas cortical SEPs are altered by halogenated anesthetics, spinal and subcortical SEPs are thought to be hardly affected. In this study the spinal N13 potential (recorded with anterior neck reference) showed a significant delay with enflurane anesthesia. The P13 and P14 far-field potentials, however, remained unchanged. Our results indicate that oligosynaptic as well as polysynaptic pathways are influenced by halogenated anesthetics and that enflurane has different effects on spinal gray matter and cuneate synapses. Our data also demonstrate that earlobe reference recordings are not adequate to measure pharmacologic effects on subcortical SEPs.

Preliminary personal experiences with the application of near-infrared indocyanine green videoangiography in extracranial vertebral artery surgery.

INTRODUCTIONWe evaluated the feasibility, usefulness, and limitations of near-infrared indocyanine green (ICG) videoangiography during procedures involving the extracranial vertebral artery (VA). METHODSNine patients (2 women, 7 men; mean age, 55 years) were evaluated at 2 neurosurgical centers. Near-infrared ICG videoangiography was applied during transposition and rerouting of the first segment of VA (V1; n = 6) and during resection of neurinomas near the second (V2; n = 1) and third (V3; n = 2) segments of VA. RESULTSEarly after ICG injection, V1 fluoresced homogenously. The fluorescence of V2 and V3 varied. Without extrinsic compression, these segments appeared as noncontiguous hot spots because the VA runs freely in a periosteal sheath surrounded by a venous plexus that attenuates the fluorescent light. Hot spots corresponded to areas where the artery neared the surface. With extrinsic compression, VA enhanced homogenously because it was pushed against the periosteal layer. During the late phase, the V1 signal was attenuated, whereas the venous plexus surrounding V2 and V3 enhanced homogeneously, thereby masking the VA itself. Near-infrared ICG videoangiography helped to confirm VA patency during transposition and rerouting but was not helpful during VA exposure because the periosteal sheath must already be exposed to detect the VA or its surrounding plexus. After exposure, videoangiography can help to determine the position of the VA within its periosteal sheath. CONCLUSIONVideoangiography can be used to provide information about the patency of the VA and its location within the periosteal sheath to prevent injury during resection of tumor adherent to the periosteal sheath.

Lumbar plexus posterior approach: a catheter placement description using electrical nerve stimulation.

IMPLICATIONS The authors describe a modified technique of posterior approach to the lumbar plexus in the psoas compartment which allows nerve stimulation for the location of the plexus and catheter placement for extended-duration surgery and postoperative patient-controlled regional analgesia. A frequent incidence of total lumbar plexus block was observed.

Sciatic nerve blockade in the supine position: A novel approach

PurposeSciatic nerve block is useful for surgery below the knee both intra- and postoperatively. Several techniques to insert a catheter at the knee level or higher have been described but need mobilization (lateral decubitus) of the patient. We describe novel landmarks, using a high lateral approach, to block the sciatic nerve without moving the patient.Clinical featuresOne hundred seven ASA I, II and III ASA patients scheduled for major foot or ankle surgery were studied prospectively. With patients awake and lying in the supine position, the catheter was introduced along novel landmarks in the peri-nervous adipose space using specifically designed material and nerve stimulation (< 0.5 mA). After a negative test dose (1% lidocaine with 1/200.000 epinephrine), 10 mL of 0.5% bupivacaine and 10 mL of 2% lidocaine were injected. Thirty minutes after performance of the block, the cutaneous and dermatomal sensory blockade were assessed using cold and pinprick tests while motor block was assessed using a modified Bromage scale. Complications and incidents were recorded. The tibial and superficial peroneal nerve were always blocked, while the deep peroneal and posterofemoral cutaneous nerves were blocked in only 97% and 83% of the patients, respectively. Anesthesia, was always present in the dermatome L5 and in the S1 dermatome in 98% of the patients. No major incidents or complications were noted. Three catheters could not be inserted and the anesthestic solution was injected through the needle.ConclusionThe lateral technique for sciatic nerve anesthesia and catheter insertion allows patients to remain in the supine position for performance of the block and catheter insertion, and results in a high rate of homogeneous anesthesia and a low incidence of side effects.RésuméObjectifPlusieurs techniques de bloc du nerfsciatique avec mise en place d’un cathéter ont déjà été décrites mais elles nécessitent la mobilisation du patient. Ce rapport décrit un abord latéral haut pour bloquer le nerf sciatique sans bouger le patient et mettre en place facilement un cathéter.Eléments cliniquesCent sept patients, ASA I, II et III, opérés au pied ou à la cheville ont bénéficié de cette technique. Leur nerf sciatique a été repéré en décubitus dorsal en utilisant une technique de stimulation nerveuse classique selon une approche adaptée de la technique latérale classique et suivant une direction céphalique. Par un cathéter introduit par l’aiguille, la solution anesthésique (10 mL de bupivacaïne à 0,5 % et 10 mL de lidocaïne à 2 %) a été injectée après une dose test négative (lidocaïne à 1 % adrénalinée à 1/200000). Trente minutes après l’injection, les tests au froid et à la piqûre ont permis l’évaluation du bloc sensitif dans les territoires nerveux et dans les dermatomes correspondants, tandis que le bloc moteur était évalué grâce à un score de Bromage modifié. Toutes les complications et incidents potentiels ont été notés. Les nerfs tibiaux et péroniers superficiels étaient toujours bloqués alors que le péronier profond et le fémoro-cutané postérieur ne l’étaient que chez 97 % et 83 % des patients. Le dermatome L5 était toujours anesthésié alors que S1 l’était dans 98 %. Aucune complication majeure n’a été notée. Trois échecs d’insertion de cathéter ont, néanmoins, conduit à l’injection de la solution anesthésique par l’aiguille.ConclusionCette technique d’anesthésie du nerfsciatique par abord latéral avec insertion d’un cathéter permet de ne pas bouger le patient et cela avec une incidence élevée d’anesthésie homogène du nerfsciatique et une faible survenue d’effets secondaires.

The anterior combined approach via a single skin injection site allows lower limb anesthesia in supine patients

PurposeLower limb anesthesia (LLA) requires the combination of, at least, three-in-one and sciatic nerve (SCN) blocks. Anterior approaches are easier to perform with minimal discomfort in supine patients, specially for traumatology. Feasibility of a single needle entry combined approach is reported.Clinical featuresThe combined landmark was applied in 119 ASA I and II patients (32–68 yr) scheduled for surgery below the knee. Needle (nerve stimulation applied through a single 150-mm long b-bevelled insulated needle) was inserted at the midpoint between the two classical approaches. Thirty and 15 mL of 0.5% ropivacaine were injected close to the femoral and the SCN, respectively. During the following 45 min, the extent of sensory block and knee and ankle motor block were assessed. Landmarks were determined within 1.7 min (0.7–2.2 min). The entire procedure was performed within 4.2 min (2.9–7.1 min) from the determination of the landmark to the SCN infiltration. The three-in-one technique was successful in 89.9% while SCN was successful in 94.9%. Femoral and tibial nerves were always blocked. Blockade of the posterior cutaneous femoral nerve was observed in 78% of patients. The extent and the quality of the sensory block always allowed surgery. Additional iv sedation was needed in 32.6% of patients. Motor block (adapted Bromage’s scale > 2) was observed in the femoral (98.3%), the obturator (84.8%), the tibial (97.4%) and the common peroneal (85.7%) nerve distributions. No important adverse effects were recorded.ConclusionThe anterior combined approach via a single needle entry represents a technically easy and reliable technique to perform LLA in the supine patient.RésuméObjectifL’anesthésie des membres inférieurs (AMI) exige la combinaison, au moins, d’un bloc trois-en-un et d’un bloc du nerf sciatique (NSC). L’abord antérieur est plus facile et n’entraîne qu’un inconfort minimal chez des patients en décubitus dorsal, surtout en traumatologie. Nous présentons l’application d’une technique combinée comportant un seul site d’injection.Éléments cliniquesLes repères combinés ont été utilisés chez 119 patients d’état physique ASA I et II, de 32 à 68 ans, devant subir une opération sous le genou. L’aiguille (stimulation nerveuse appliquée avec une aiguille isolée, biseautée, de 150 mm) a été insérée au centre des deux points d’abord habituels. Des doses de 30 et 15 mL de ropivacaïne à 0,5 % ont été respectivement injectées près du nerf fémoral et du NSC. Pendant les 45 min suivantes, l’étendue du bloc sensitifet du bloc moteur au genou et à la cheville a été évaluée. Les repères ont été déterminés en 1,7 min (0,7–2,2 min). L’application de la technique a demandé 4,2 min (2,9–7,1 min) à partir de l’identification du repère jusqu’à l’infiltration du NSC. La technique du troisen-un a été réussie dans 89,9 % des cas et celle du NSC dans 94 %. Les nerfs fémoral et tibial ont été aussi anesthésiés. Le bloc du nerf cutané fémoral postérieur a été observé chez 78 % des patients. L’étendue et la qualité du bloc sensitif ont permis l’opération dans tous les cas. Une sédation iv complémentaire a été nécessaire chez 32,6 % des patients. Le bloc moteur (échelle de Bromage > 2) a été observé pour les territoires des nerfs suivants : fémoral (98,3 %), obturateur (84,8 %), tibial (97,4 %) et sciatique poplité externe (85,7 %). Aucun effet indésirable important n’a été enregistré.ConclusionLa méthode antérieure combinée comportant un seul site d’injection est une technique facile et fiable pour réaliser une AMI chez le patient en décubitus dorsal.

Intraoperative somatosensory evoked potentials to facilitate peripheral nerve release

PurposeThe significance of intraoperative somatosensory evoked potentials (SSEP) monitoring is well known during spinal surgery. This technology could be beneficial during peripheral nerve surgery as well. In order to illustrate potential applications, two cases of successful peripheral nerve release demonstrated by on-line, intraoperative, SSEP are reported.Clinical and technical featuresThe first case presents a complex brachial plexus lesion involving two mixed sensorymotor nerves: median and ulnar. The second case involved an entrapment neuropathy of the lateral femoral cutaneous nerve, a pure sensory nerve (meralgia paresthetica). For each patient we elicited specific peripheral nerve SSEP (recorded using bipolar cephalic montage) by stimulating each nerve independently. In each case, during difficult nerve dissection and after having excluded other possible factors of intraoperative SSEP variations, an increase of the SSEP amplitude was observed, and later correlated with favourable patient clinical outcome.ConclusionsTw o cases demonstrate that intraoperative SSEP monitoring may provide an effective tool to guide surgical dissection during peripheral nerve release. This technique has potentially beneficial clinical applications and warrants further investigation.RésuméObjectifLa valeur du monitorage par les potentiels évoqués somesthésiques (PES) pendant une opération de la colonne vertébrale est bien connue. Il peut offrir des avantages pendant la chirurgie des nerfs périphériques. Pour illustrer ses applications possibles, nous présentons deux cas de libération réussie de nerfs périphériques démontrée par les PES peropératoires en ligne.Caractéristiques cliniques et techniquesLe premier cas concerne une lésion complexe du plexus brachial touchant deux nerfs mixtes sensori-moteurs: médian et cubital. Le second cas porte sur une neuropathie de compression du nerf cutané fémoral latéral, un nerf sensitif (méralgie paresthésique). Pour chaque patient, nous avons suscité les PES du nerf périphérique concerné (enregistrés selon un montage céphalique bipolaire) en stimulant chaque nerf séparément. Dans chaque cas, pendant la dissection difficile du nerf et aprs avoir exclu tout autre facteur possible de variation des PES peropératoires, une hausse de ľamplitude des PES a été observée et corrélée ensuite avec ľévolution clinique favorable du patient.ConclusionLes cas présentés montrent que le monitorage peropératoire par les PES peut guider efficacement la dissection chirurgicale pendant la libération ďun nerf périphérique. Il a des applications cliniques potentiellement bénéfiques et devrait être étudié plus avant.

La séedation et i’anesthésie pour i’endoscopie digestive

RésuméEn Belgique, la majorité des sédations pour endoscopies digestives est effectuée par l’endoscopiste. L’anesthésiste n’est généralement requis que pour des examens spéciaux, longs ou douloureux.L’utilisation correcte des benzodiazépines (BZD) et des opiacés nécessite la connaissance de leur pharmacologic Le diazepam (D) et le midazolam (M) procurent le même degré de sédation et de cooperation de la part du patient. Lorsqu’une seule dose équivalente est injectée, la recouvrance se fait dans un temps similaire, dépendant du temps de distribution (T 1/2 α D: 15-25 min; M: 14-18 min). Le M est 1,7 à 2 fois plus puissant que D, agit plus vite et est plus vite éliminé (T 1/2 β D: 25-50 H; M: 2-4 H). A doses répétées, le D agit plus longtemps, la recouvrance et les tests psychomoteurs sont davantage et plus longtemps perturbes. Son metabolite actif, le desméthyldiazepam a une longue 1/2 vie d’élimination (T 1/2 β 36-200 h). La dépression respiratoire est semblable pour les 2 drogues, trés marquee et de longue durée chez les patients souffrant d’affection respiratoire obstructive chronique. Le M déprime davantage le systéme cardiovasculaire. L’amnesie de type antérograde est plus marquée avec M.La péthidine est l’opiacé le plus communément utilisé par les endoscopistes. Elle déprime la respiration et le systéme cardiovasculaire de facon marquee. Son métabolite la norpéthidine, est un psychostimulant et un convulsivant.L’âge, le sexe, les antécédents, l’etat général (insuffisance hépatique, rénale, hypoprotéinémie, hypovolémic...) peuvent influencer la pharmacocinétique et la pharmacodynamic des BZD et des opiacés. La bonne connaissance du dossier du patient est done indispensable. Dans ce but, une solution concernant les patients ambulants est suggérée.Les antagonistes flumazénil et naloxone sont efficaces, mais donnent un sentiment de fausse sécurité, vu leur courte durée d’action.Certains opiacés puissants et de courte durée d’action (fentanyl, alfentanil), les anesthésiques généraux intraveineux (barbituri-ques, étomidate, propofol) ou par inhalation sont du domaine exclusif des anesthésiologistes. Parmi ces drogues, le propofol, par sa maniabilité et la qualité du réveil, est une drogue de choix, mais non dépourvue d’effets secondaires (apnée, dépression cardiovascu-laire). Les régies de sécurité appliquées au bloc opératoire doivent être respectées en salle d’endoscopie: surveillance du patient par une personne compétente, appareillage adéquat, source d’oxygéne, monitoring, matériel et drogues de réanimation cardiorespiratoire.Après ’intervention, le patient doit pouvoir bénéficier d’une surveillance dans une salle de réveil ou de repos avant que son retour en salle ou á domicile ne soit autorisé. Il ne peut ni conduire, ni manipuler de machines pendant 24 h. La responsabilité médico-légale de ’endoscopiste et de l’anesthesiste est rappelee.SummaryIn Belgium the great majority of sedations for GI endoscopies are performed by the endoscopist himself. The anesthesiologist is generally required for special, long or painful procedures.The proper use of benzodiazepines (BZD) and opiates depends on the knowledge of their pharmacology. Diazepam (D) and Midazolam (M) provide the same degree of sedation and cooperation from the patient.When one bolus of an equipotent dose is injected, recovery time is similar for both drugs, depending on the time of distribution (T 1/2 α D: 15-25 min; M: 14-18 min). M is 1.7 to 2 times more potent than D, its onset of action is shorter and it is rapidly eliminated ( T 1/2 β D: 25-50 H; M: 2-4 H). When larger or repeated doses of D are injected, recovery time is longer and psychomotor tests are more affected and delayed. Its active metabolite desmethyldiazepam has a long elimination half-line (T 1/2 36-200 h).Respiratory depression exists for both drugs, more pronounced and of greater duration in the COPD patient. Cardiovascular system is more depressed with M. Anterograde amnesia is more marked with M.Pethidine is the most commonly used opioid by endoscopists. Both respiration and cardiovascular system are markedly depressed. Its metabolite norpethidine is a psychostimulant and convulsivant drug.Age, sex, the medical history, the general status (hepatic and renal failure, hypoproteinemia, hypovolemia...) can influence the pharmacokinetics and the pharmacodynamics of BZD and opiates. The good knowledge of the patients record is thus mandatory. In this respect a solution for out- patients scheduled for endoscopy is suggested.The antagonists flumazenil and naloxone are effective but can give a false sense of security because of their short half-life. Some potent and short-acting opioids (fentanyl, alfentanil), general intravenous anesthetics (barbiturates, etomidate, propofol) or inhalational anesthetics are strictly reserved to anesthesiologists. Among these drugs, propofol seems to be a drug of choice: it can be used as repeated bolus or as a continuous infusion which can be easily modulated according to the desired depth of anesthesia. It is not devoid of adverse effects (apnea and cardiovascular depression). As the forensic responsability of the endoscopist and the anesthesiologist is involved, the safety rules recommended in the operating theater must be of application in the endoscopy room, which must be equipped with oxygen, suction, a good monitoring (EKG, pulseoxymeter, capnometer) a blood pressure monitor, all the material and drugs for CPR ressuscitation, an anesthesia machine if necessary, and first of all a trained person must take care of the patient during the procedure.After the procedure, the patient must be watched closely in a recovery or rest room before he is allowed to return to the ward or to leave the hospital. He is not authorized to drive or to operate machinery for 24 h.ResumenEn Belgica, la mayoria de les sedaciones en endoscopia digestiva son realizadas por los endospistas. El anesthesiologo es requerido en procedimientos especiales, largos o dolorosos.Para usar correctamente las Benzodiacepinas (BZD) y opiáceos es necesario el conocimiento de su farmacologiá. Diacepam (D) y Midazolam (M) tienes mismo-grado de sedatión y de cooperatión por parte del paciente. Quando se inyecta una sola dosis equivalente, la recuperatión es en tiempo similar, de-pendiendo del tiempo de distributión (t 1/2 α D: 15-25 min; M: 14-18 min). El MMZ es 1,7 a 2 veces mas potente que el D, actua mas rápido y es eliminado también más rapidamente (t 1/2 β D: 25-50 H; M: 2–4 H). Cuando se dan dosis repetidas, el D act mas tiempo, los test psicomotores tardan más en normalizarse. El desmethydiace-pam (metabolito activo de D) tiene una 1/2 vida eliminacion muy larga (T 1/2 β 36-200 H). La depresión respiratoria es identica para las dos drogas; mucho más marcada en aquellos pacientes afectos de BNCO. EI M deprime más el sisteme cardiovascular asi como tiene mayor poder de amnesia anterograda.La pethidina es el mórfico mas utilizado por los endoscopistas. Tiene una accion depresiva cardiovascular y respiratoria importante. La norpethidina (su metabolito) es psicoestimulante y convulsivante.La edad, sexo, antecedentes, estado general (Insuf. hepatica, renal, hipoproteinemia, hipovolemia...) pueden influenciar la farmacocinetica y farmacodinamica de las BZD y opiáceos. El buen conocimiento del dossier del paciente es indispensable. Con este objetivo hay que tomar soluciones con los pacientes ambulatorios.Los antagonistas flumazenil y naloxona son eficaces; pero dan la impresión de falsa seguridad en relatión con su corta acción.Algunos mórficos potentes y de corta acción (Fentanyl, alfentanil), los anesthesicos grales. Intravenosos (barbituricos, etomidato, propofol) ó inhalatorios son de uso exclusivo de los anesthesistes. Entre todas estas drogas, el propofol, por su manejabilidad, calidad del despertar, es de electión. Sin embargo no esta desprovista de efectos secundarios (apnéa, depression cardiovascular). Las reglas de seguridad aplicadas en quirofano tienen que serlo tambien en la sala de endoscopia: vigilancia por personal competente, monitorage adecuado, fúente O2, material y drogas para reanimación cardiorespiratoria.Al finalizar la interventión el patiente debe ser controlado en una sala de despertar antes de su vuelta a la habitatión o domicilio. Se le desautoriza a conducir o manipular máquinas durante 24 h. A tener en cuenta la responsabilidad médico-legal del anesthesiólogo y del endoscopista.