No evidence of memory processing during propofol-remifentanil target-controlled infusion anesthesia with bispectral index monitoring in cardiac surgery.

OBJECTIVE: Auditory information presented during anesthesia can activate memory. Surgical stimulation may enhance memory formation. The authors' hypothesis is that implicit memory processing is not preserved during unconsciousness, even in the presence of a surgical stimulus. DESIGN: A double-blind randomized controlled trial. SETTING: A single-institution, university hospital. PARTICIPANTS: Thirty-eight adults undergoing cardiac surgery. INTERVENTIONS: Patients were randomized to continuously hear either disc A or B during surgery. On each disc, 20 different words were recorded. MEASUREMENTS AND MAIN RESULTS: Implicit and explicit memory were tested. The study design was that each group served as a control for the other. The responses from both groups on both lists allowed the authors to compare the likeliness of correctly identifying the words from a list whether it was heard while under anesthesia or not. During the interview, no patient had explicit recall as investigated by the free recall test, and no one reported dreaming. As for implicit memory processing, the difference between the mean rate of correct answers on the word-stem completion test for the disc the patients heard (3.42% for disc A and 13.15% for disc B) or did not hear (3.15% for disc A and 14.73% for disc B) was not statistically significant (p = 0.95 for A and p = 0.42 for B). CONCLUSIONS: Explicit and implicit memory were not detectable in patients anesthetized with an effect-site target-controlled infusion of propofol and remifentanil with bispectral index monitoring. These results suggest that there is no memory processing under anesthesia in the surgical setting.

Anesthetic considerations for awake craniotomy for epilepsy.

A variety of anesthetic methods, with and without airway manipulation, are available to facilitate awake intraoperative examinations and cortical stimulation, which allow more aggressive resection of epileptogenic foci in functionally important brain regions. Careful patient selection and preparation combined with attentive cooperation of the medical team are the foundation for a smooth awake procedure. With improved pharmacologic agents and variety of techniques at the neuroanesthesiologist's disposal, awake craniotomy has become an elegant approach to epileptic focus resection in functional cortex.

[Safety of tumescent liposuction]. / Hohe Sicherheit der Tumeszenz-Liposuktion.

Liposuction surgery is increasing in frequency and is the most commonly performed cosmetic procedure to date. Regularly, complications and fatalities are reported by tabloids. The anaesthesiogical techniques used, however, are usually not reported. Tumescent liposuction has to be clearly separated from liposuction with intravenous sedation or under general anaesthesia. In tumescent liposuction, tumescent fluid containing saline, lidocaine and adrenaline is injected into the undesired fat deposits and the pain is controlled locally. In contrast, when liposuctions are performed either with intravenous sedation or under general anaesthesia, the patient is unconscious. In this study, the different anaesthesiological techniques currently used for liposuction were compared with each other. Reported fatalities were reviewed and it was determined, whether liposuction was performed as tumescent liposuction or if systemic sedation was used. To date, no fatalities were reported when tumescent liposuction was performed and a total of 396 457 liposuctions (including own unpublished data) was counted. Fatalities, however, were reported, when either intravenous sedation or general anaesthesia was performed, and a mortality rate of 2.6-19.1 per 100000 cases was counted. Liposuctions should therefore, whenever possible be performed as tumescent liposuction. Intravenous sedation or general anaesthesia should be more carefully considered.

Premedication with gabapentin: the effect on tourniquet pain and quality of intravenous regional anesthesia.

BACKGROUND: Gabapentin, an oral non-opioid analgesic, has been used to decrease pain after a variety of surgical procedures. We hypothesized that premedication with gabapentin would minimize tourniquet-related pain in patients receiving IV regional anesthesia (IVRA). METHODS: Patients undergoing elective hand surgery with IVRA were randomly assigned to one of two study groups using a double-blind study design. The control group (n = 20) received placebo capsules 1 h before the surgery, and the gabapentin group (n = 20) received gabapentin 1.2 g p.o. before the operation. IVRA was achieved in all patients with lidocaine, 3 mg/kg, diluted with saline to a total volume of 40 mL. Fentanyl, 0.5 microg/kg IV, was administered as a rescue analgesic during surgery. Sensory and motor block onset and recovery times, tourniquet pain, and quality of anesthesia were assessed at specific time intervals during the perioperative period. Visual analog scale pain scores (0-10) were recorded during the 24 h follow-up period, and patients received diclofenac, 75 mg IM, if their pain score was >4. RESULTS: The onset of the sensory and motor block did not differ between the two study groups. However, tourniquet pain scores at 30, 40, 50, and 60 min after cuff inflation were lower in the gabapentin group (P < 0.05). The time to intraoperative analgesic rescue was prolonged in the gabapentin group (35 +/- 10 min vs 21 +/- 13 min, P < 0.05), and less supplemental fentanyl was required (35 +/- 47 microg vs 83 +/- 73 microg, P < 0.05). The quality of anesthesia, as independently assessed by the anesthesiologist and the surgeon, was significantly better in the gabapentin (versus control) group. In the gabapentin group, the time to requesting a rescue analgesic after surgery was prolonged (135 +/- 25 min vs 85 +/- 19 min, P < 0.05), and postoperative pain scores at 60 min (3.8 +/- 0.9 vs 2.2 +/- 0.5) and 120 min (3.2 +/- 1.4 vs 1.8 +/- 0.8), as well as diclofenac consumption (30 +/- 38 mg vs 60 +/- 63 mg), were reduced after surgery. CONCLUSIONS: Premedication with oral gabapentin (1.2 g) decreased tourniquet-related pain and improved the quality of anesthesia during hand surgery under IVRA. Gabapentin also reduced pain scores in the early postoperative period.

Vocal cord dysfunction: a case report.

Vocal cord dysfunction (VCD) is a respiratory condition characterized by the paradoxical closure of the vocal cords. This condition results in a myriad of symptoms that would be expected from an upper airway obstruction including anxiety, hyperventilation, wheezing, stridor, shortness of breath, dyspnea, and suprasternal and neck muscle retraction. with known VCD who underwent local anesthesia with intravenous sedation for perianal skin tag removal. Postoperatively, the patient experienced respiratory distress, prompting interventions and investigation. A review of the literature revealed limited information on VCD, and no anesthesia literature was found regarding this entity.

Short-term low-dose propofol anaesthesia associated with severe metabolic acidosis.

Propofol-induced metabolic acidosis is well recognised in the paediatric literature, but the existence of such a syndrome in adults remains contentious. In most reported cases, metabolic acidosis complicated prolonged administration of propofol in critically ill patients. We present a case of severe non-fatal reversible metabolic acidosis, without ventilatory depression or hypoxia, related to short-term propofol infusion in an adult during and after coronary artery bypass grafting. We suggest that lactic acidosis occurred in a genetically susceptible patient with an abnormality of mitochondrial function. This report discusses an unusual adverse effect of propofol anaesthesia and sedation and highlights the need for further investigation to define propofol toxicity.

Anaesthesia and the acute phase protein response in children undergoing circumcision.

Concentrations of acute phase proteins (CRP: C-reactive protein, albumin) change during surgery. We investigated the acute phase response to circumcision and the effects of anaesthesia on this response. The children were divided into four groups; group 1 (intratracheal general anaesthesia, n=40), group 2 (general anaesthesia with mask, n=20), group 3 (ketamine, n=20), group 4 (local anaesthesia, n=35). Blood samples were obtained, 24 hours before circumcision, after premedication, and 24 hours after circumcision. CRP and albumin before circumcision were comparable for all groups. There was no increase in CRP, and albumin remained steady throughout the study. No difference was observed among the groups, and related to anaesthesia. No responsiveness may be explained with the size of injured tissue or anatomical and histological type of preputium.

[Addition of clonidine to 0.5% lidocaine for intravenous locoregional anesthesia]. / Adjonction de clonidine à la lidocaïne à 0,5% pour anesthésie locorégionale intraveineuse.

OBJECTIVE: Evaluate the effect of the addition of clonidine to lidocaine on postoperative pain after intravenous regional anaesthesia. STUDY DESIGN: Double blind prospective study. PATIENTS AND METHODS: Forty-five patients were randomly allocated to two groups: group 1 (n = 25) receiving 3 mg.kg-1 of lidocaine 0.5% added to saline and group 2 (n = 20) receiving 3 mg.kg-1 of lidocaine 0.5% added to clonidine (150 micrograms). Postoperative analgesia was assessed using a visual analogue pain score (VAPS) and the time to first analgesic request. The incidence of side effects after tourniquet release was noted. Analysis of variance, Kruskall Wallis and chi 2 tests were used for statistical analysis. A p-value of < 0.05 was considered significant. RESULTS: Age, ASA class, duration and type of surgery, tourniquet time and sensory block duration were comparable for the two groups. The time to first antalgic request after deflation of tourniquet was similar in the two groups (38 +/- 15 min versus 44 +/- 19 min), while VAPS score was lower (p < 0.05) in the clonidine group (5.2 versus 6.8). The incidence of side effects was comparable in the two groups. CONCLUSION: The addition of clonidine (150 micrograms) to lidocaine for intravenous regional anaesthesia improved postoperative analgesia but in a limited and short-lasting manner.

Presentación de un caso de hipertermia maligna con diagnóstico ratificado por el puntaje de NAMHR (North American Malignant Hyperthermia Registry) / Presentation of a case of malignant hyperthermia ratified by NAMHR's (North American Malignant Hyperthermia Registry) score

Introducción: Desarrollo de cuadro clínico de hipertermia maligna en un paciente anestesiado con anestesia endovenosa total. Diagnóstico a través del puntaje del North American Malignant Hyperthermia Registry. Caso clínico: Se presenta un caso clínico de hipertermia maligna acontecido en nuestro servicio, con la particularidad de haberse desencadenado durante el intraoperatorio de una cirugía bajo anestesia intravenosa total. Paciente de 30 años, con diagnóstico de hidronefrosis; se anestesió con midazolam, remifentanilo y mivacurio. Luego de 1 hora de cirugia y sin causa clínica aparente, comenzó con hipotensión. Simultánea y progresivamente, se taquicardizó alcanzando valores de 155'. Se tomó 37.8 §C de temperatura axilar. La ETCO2 era de 75 mmHg. Luego, la temperatura se elevó a 43 §C y se decidió tratar con dantrolene. Discusión: La carencia de un método precoz de diagnóstico de HM, sumada a cambios metabólicos rápidos, hipermetabolismo marcado y excesiva producción de calor, nos enfrenta al dilema de iniciar el tratamiento específico -dantrolene-, que evite secuelas irreversibles o la muerte. Conclusiones: Creemos que la clasificación con el puntaje del North American Malignant Hyperthermia Registry, por la simplicidad de su diseño y facilidad de aplicación, puede ser un método útil e indispensable como método de screening en aquellos pacientes en que por alguna causa se sospecha una susceptibilidad o un cuadro de HM.

Presentación de un caso de hipertermia maligna con diagnóstico ratificado por el puntaje de NAMHR (North American Malignant Hyperthermia Registry) / Presentation of a case of malignant hyperthermia ratified by NAMHRs (North American Malignant Hyperthermia Registry) score

Introducción: Desarrollo de cuadro clínico de hipertermia maligna en un paciente anestesiado con anestesia endovenosa total. Diagnóstico a través del puntaje del North American Malignant Hyperthermia Registry. Caso clínico: Se presenta un caso clínico de hipertermia maligna acontecido en nuestro servicio, con la particularidad de haberse desencadenado durante el intraoperatorio de una cirugía bajo anestesia intravenosa total. Paciente de 30 años, con diagnóstico de hidronefrosis; se anestesió con midazolam, remifentanilo y mivacurio. Luego de 1 hora de cirugia y sin causa clínica aparente, comenzó con hipotensión. Simultánea y progresivamente, se taquicardizó alcanzando valores de 155. Se tomó 37.8 ºC de temperatura axilar. La ETCO2 era de 75 mmHg. Luego, la temperatura se elevó a 43 ºC y se decidió tratar con dantrolene. Discusión: La carencia de un método precoz de diagnóstico de HM, sumada a cambios metabólicos rápidos, hipermetabolismo marcado y

[Locoregional intravenous anesthesia]. / Anesthésie locorégionale intraveineuse.

OBJECTIVE: To analyse current data on intravenous regional anaesthesia (IVRA), its benefits and drawbacks. DATA SOURCES: Articles were obtained from a Medline search using the following search terms: 'intravenous regional anaesthesia', alone or combined with 'local anaesthetic agents', 'toxicity'. STUDY SELECTION: Following articles in English and in French have been selected: main articles, original articles, update and review articles, letters to the editor and recent editorials. DATA EXTRACTION: Physiopathological and pharmacological data were extracted for involved mechanisms and means for improving this technique. DATA SYNTHESIS: IVRA is a reliable and efficient technique with a lower cost than general anaesthesia and well adapted for limb surgery in the ambulatory patient. Depending on the site of the surgical field, the pneumatic tourniquet is set either on the arm, forearm or wrist for the upper limb or thigh, calf or ankle for the lower limb. When set in periphery, less local anaesthetic agent is required. A wide tourniquet requires a lower inflation pressure than a double cuff tourniquet. A single cuff is as efficient as a dual cuff if shape, size and inflating pressure are appropriate. The limb occlusion pressure (LOP) is the minimal pressure required to occlude blood flow. It is assessed with either a pulse oximeter or Doppler for determination of the lowest cuff inflating pressure. The cuff is inflated to 50 mmHg above LOP. Oozing in the surgical field can be decreased by the re-exsanguination technique. Currently, lidocaine is the only local anaesthetic released in France for IVRA. Addition of a muscle relaxant, a NSAID or clonidine allows the dose of local anaesthetic agent to be decreased and improves postoperative analgesia.

Where there is no anaesthetist: a study of 282 consecutive patients using intravenous, spinal and local infiltration anaesthetic techniques.

Two hundred and eighty-two consecutive surgical operations were performed over a period of 11 months, February-September, 1991, December 1991-February 1992 at two private medical centres. Anaesthesia was conducted by the surgeon assisted by the theatre nurses. Intravenous ketamine was given in 72% of operations, xylocaine infiltration in 12.8%, spinal anaesthesia in 11.3% and intravenous thiopentone anaesthesia in 4% of the patients. Major and minor surgical operations were performed on 180 (63.9%) and 102 (36.2%) patients, respectively. With ketamine anaesthesia side effects included transient intra-operative hypertension in 76.8%, delirium/confusion in 56.7% and dreams in 5.4% of the patients. Hypotension at induction and postoperative headache/neck stiffness were the principal side effects in spinal anaesthesia occurring in 59.2% and 12.8%, respectively. Reversible apnoea occurred in three patients and cardiac arrest in one patient of those who had intravenous thiopentone. It appeared, therefore, that where there is no anaesthetist as is often the case in under-doctored areas, after careful patient selection, intravenous ketamine, spinal and local infiltration anaesthetic techniques are safe and useful for many surgical procedures. There is the need to avoid intravenous thiopentone by untrained personnel and in settings poorly equipped for cardiopulmonary resuscitations.

Reducing pain during propofol injection: the role of the solvent.

We hypothesized that the concentration of propofol in the aqueous phase may be the most important variable responsible for the pain experienced during injection of the drug. The concentration of propofol in the aqueous phase (18.57 micrograms/mL) can be decreased by increasing the fat content of the solvent. To test this hypothesis, 36 patients were randomly allocated to one of three groups, each receiving a different formulation of propofol. Group A received 20 mL of propofol alone in a commercial preparation (Diprivan(R) with 10 mL of saline); Group B, 20 mL of propofol to which 5 mL of long-chain triglyceride (LCT) fat emulsion and 5 mL of saline and been added; and Group C, 20 mL of propofol and 10 mL of LCT fat emulsion. The propofol emulsion was injected over 30-60 s into a dorsal vein of the hand. Patients reported pain during injection as none, mild, moderate, or severe (almost intolerable). In Group A, 8 of 12 patients reported moderate or severe pain upon injection whereas in Group C only mild pain was reported by 6 of 12 patients. Our results suggest that a smaller concentration of propofol in the aqueous phase of the emulsion reduces pain on injection. With the addition of more lipid (10 mL), a higher percentage of propofol is absorbed by fat particles. If solvents that permit a smaller concentration of the drug in the aqueous phase of oil-in-water emulsions were used for propofol and other drugs that cause pain on injection, pain would be reduced and patient satisfaction may be increased.

Pain on injection of propofol.

A controlled randomized double-blinded clinical study was undertaken to evaluate and compare the efficacy of three methods of preventing pain during injection of propofol on induction of anesthesia. Patients were randomly allocated to six groups: saline pretreatment, followed by induction with propofol at room temperature plus saline; lidocaine pretreatment, followed by induction with propofol at room temperature plus saline; saline pretreatment, followed by induction with propofol at a temperature of 4 degrees C plus saline; lidocaine pretreatment, followed by induction with propofol at a temperature of 4 degrees C plus saline; saline pretreatment, followed by induction with propofol at room temperature plus lidocaine 40 mg; saline pretreatment, followed by induction with propofol at a temperature of 4 degrees C plus lidocaine 40 mg. Pretreatment with lidocaine reduced the incidence of pain and discomfort significantly compared with unpretreated groups. Groups which received propofol mixed with lidocaine also showed a significant reduced incidence of pain. induction with cold 4 degrees C propofol showed no significant difference in reduction of injection pain.

Morbidity and mortality with outpatient anesthesia: the Massachusetts experience.

All 147 active members of the Massachusetts Society of Oral and Maxillofacial Surgeons responded to an anesthesia survey. They had treated 416,561 patients during 1989. This article reports the results of the survey and specific untoward anesthetic events as recalled by these practitioners. Use of various anesthetic agents in 1989 and 1984 are compared.

The minimum effective dose of lignocaine to prevent injection pain due to propofol in children.

In a single-blind study of 100 children aged 1 to 10 years, the minimum effective dose of lignocaine required to prevent injection pain due to propofol was 0.2 mg.kg-1 when veins on the dorsum of the hand were used. This is more than twice the adult value. We concluded that injection pain should not limit the use of propofol in children if an adequate amount of lignocaine is mixed immediately prior to injection.

Oxygen saturation during third molar removal with local anaesthetic alone and in combination with intravenous sedation.

Oxygen saturation was recorded in 96 adults undergoing removal of third molar teeth in the dental surgery. Half the patients received local anaesthetic alone; the remainder received, in addition, intravenous midazolam. Patients receiving sedation sustained the greatest falls in oxygen saturation. However, in 10 out of 48 patients undergoing third molar removal with LA alone, oxygen saturations in the range of 93-89% were recorded. The results of this study suggest that all patients undergoing removal of third molars are at risk of hypoxia. Short episodes of hypoxia may be of little consequence in healthy patients, but in compromised patients early detection may avoid serious complications.