BACKGROUND: Spectral entropy of the electroencephalogram (EEG) has been proposed to monitor anaesthetic depth. We investigated the effect of nitrous oxide on response (RE) and state entropy (SE) of the EEG during lumbar disc surgery under anaesthesia with sufentanil and sevoflurane. METHODS: In an open study, anaesthesia was induced with propofol and sufentanil, and maintained with 2% end-tidal sevoflurane concentration in air/oxygen (FiO2 = 0.4) in 25 patients. During surgery, nitrous oxide was randomly administered either at 0 or at 60% end-tidal concentration in 10 (control group) and 15 patients (nitrous oxide group), respectively. RE and SE were recorded at 2.5 min intervals for 10 min before randomization and for 25 min either continuously (control) or after achieving the target nitrous oxide concentration. RESULTS: Two patients who received nitrous oxide were excluded from statistical analysis because of protocol violation. Nitrous oxide provoked a significant decrease in RE and SE from 46.2 +/- 11.1 and 44.3 +/- 11.1 to a lowest value of 27.8 +/- 8.3 and 27.1 +/- 8.9, respectively. The decrease in entropy persisted during the 25 min recording period. CONCLUSIONS: Addition of nitrous oxide during balanced anaesthesia with sufentanil and sevoflurane provokes a decrease in response and state entropy of the EEG during lumbar disc surgery.

Adult↗

PubMed2005

The cervical spine in trauma: implications for the anaesthesiologist.

In this paper, the authors review the most recent literature concerning the management of the cervical spine in trauma patients. They address the main topics of concern for the anaesthesiologist including pre-hospital care, clearance of the cervical spine, neuroprotective therapies, difficult tracheal intubation, and management during general anaesthesia, in the intensive care unit and in paediatric patients. The most widely accepted strategies are provided as well as alternative options.

Adult↗

PubMed2004

Comparative effects of ketamine on Bispectral Index and spectral entropy of the electroencephalogram under sevoflurane anaesthesia.

BACKGROUND: The Bispectral Index (BIS) and spectral entropy of the electroencephalogram can be used to assess the depth of hypnosis. Ketamine is known to increase BIS in anaesthetized patients and may confound that index as a guide to steer administration of hypnotics. We compared the effects of ketamine on BIS, response entropy (RE) and state entropy (SE) during surgery under sevoflurane anaesthesia. METHODS: Twenty-two women undergoing gynaecological surgery were enrolled in this double-blind, randomized study. Anaesthesia was induced i.v. and maintained with sevoflurane. Under stable surgical and anaesthetic conditions, patients were assigned to receive either a bolus of ketamine 0.5 mg kg(-1) or the same volume of saline. Blood pressure, heart rate, BIS, RE and SE were measured every 2.5 min from 10 min before (baseline) until 15 min after ketamine or saline administration. The maximum relative increase in BIS, RE and SE compared with baseline was calculated for each patient. Values are mean (sd). RESULTS: Baseline values were BIS 33 (4), RE 31 (5), SE 30 (5) for the ketamine patients and BIS 35 (3), RE 33 (5) and SE 32 (6) for the patients receiving saline. BIS, RE and SE increased significantly from 5 min (BIS) and 2.5 min (RE and SE) after ketamine administration, peaking at 46 (8) (BIS), 52 (12) (RE) and 50 (12) (SE) respectively. The maximum relative increase in RE [42.2 (10.4%)] and SE [41.6 (10.9)%] was higher than that of BIS [29.4 (10.4%)]. Blood pressure, heart rate and RE-SE gradient did not change in either group. CONCLUSIONS: Ketamine administered under sevoflurane anaesthesia causes a significant increase in BIS, RE and SE without modification of the RE-SE gradient. This increase is paradoxical in that it is associated with a deepening level of hypnosis.

Adult↗

PubMed2004

[Anaesthetic management of awake craniotomy].

This review article presents a detailed analysis of patients' management for awake craniotomy, at the light of the available data in the literature and the authors' experience. Indications of this type of surgery are discussed as well as anaesthetic management itself, from preoperative assessment of the patient to peroperative concerns. Anaesthetic strategy, choice of anaesthetic agents, anaesthetic technique, and management of the airway and possible complications are discussed. The authors emphasize the tricky aspect of the procedure, the necessity of rigorous patient selection and good preparation. They emphasize the need for controlled studies to validate the proposed techniques.

Anesthesia, Local↗

PubMed2004

The rationale for perioperative brain protection.

Perioperative brain protection refers to prophylactic measures instituted during the perioperative period to prevent or reduce ischaemic damage and to improve neurological outcome. In that context, strategies for protecting the brain rely on the control of physiological variables, anaesthesia, administration of non-anaesthetic pharmacological agents and preconditioning. Avoiding hyperthermia, hyperglycaemia and arterial hypotension are passive neuroprotective measures acknowledged in human beings. The protective effect of anaesthesia, compared to the awake state, is demonstrated in animals but remains to be validated in clinical practice. Laboratory studies investigating pharmacological neuroprotection have shown interesting results but most clinical trials have been disappointing except for a few drugs in specific settings. Preconditioning which results in the induction of some resistance to ischaemia appears as a promising strategy. Up to now, the translation of beneficial experimental results into clinical success is considered an entirely permissible hope but remains an unachieved objective.

Anesthesia↗

PubMed2004

Monitoring depth of anaesthesia: is it worth the effort?

In this review paper, the authors critically analyse the use of a number of depth of anaesthesia monitors in light of the most recent literature and their own clinical experience. There appears to be increasing evidence that anaesthesia depth monitors reduce the incidence of unexpected intraoperative awareness and also that they improve the quality of anaesthesia. Proper use of these monitors necessitates background knowledge about the physiology of the loss of consciousness, the type of variable recorded and processed by the monitoring devices, the factors that might interfere with recording and the limits of use. The information provided by anaesthesia depth monitors is detailed and relationships with clinical practice are established to provide the reader with key features for optimal use of those monitors and correct interpretation of data. Practitioners and patient's knowledge and expectations regarding this matter, as well as the cost-benefit relationship are also discussed.

Anesthesia, General↗

PubMed2004

Recovery from neuromuscular block after an intubation dose of cisatracurium and rocuronium in lumbar disc surgery.

BACKGROUND AND OBJECTIVE: Residual muscle paralysis remains a concern for anaesthesiologists. This study investigated the recovery from neuromuscular block (NMB) after an intubation dose of cisatracurium (C) or rocuronium (R) in 32 patients undergoing lumbar disc surgery. METHODS: Anaesthesia was induced with propofol and sufentanil, and maintained with sevoflurane in nitrous oxide/oxygen. Patients were randomised to receive twice the ED95 of either cisatracurium (GC) or rocuronium (GR) before tracheal intubation. After placement in prone position, neuromuscular transmission was monitored at the wrist by accelerometry. NMB was antagonised when the TOF ratio (TOFR) was < 0.75 at muscle closure. The time from muscle relaxant to muscle closure, and to TOFR of 0.25 and of 0.50 were recorded. Data were analysed using Student's t-tests, chi-squared tests and two-way mixed-designed ANOVA's. The prediction probability (Pk) of the times from muscle relaxant to muscle closure, and to TOFR of 0.25 for the necessity to antagonize NMB was calculated in both groups. P < 0.05 was considered statistically significant. RESULTS: NMB was antagonized in 8 (GC) and 6 (GR) patients, respectively. The time from muscle relaxant to muscle closure was shorter in patients whose NMB was antagonized. The Pk of this time was significant in GC (0.85) but not in GR (0.69). In GR contrarily to GC, the times to a TOFR of 0.25 and 0.50 were longer in patients whose NMB was antagonized. The Pk of the time to TOFR of 0.25 was significant in GR (0.95) but not in GC (0.64). CONCLUSIONS: A single dose of cisatracurium or rocuronium may be associated to some degree of NMB at the end of lumbar surgery, depending on the duration of surgery and on the duration of action of the muscle relaxant which is more variable for rocuronium than for cisatracurium.

Adult↗

PubMed2003

Muscle relaxants in neurosurgical anaesthesia: a critical appraisal.

The use of muscle relaxants, considered until recently as common practice in current neurosurgical anaesthesia protocols, becomes increasingly more questionable today. The reasons rely on the evolution of neurosurgery including the advent of new surgical techniques, the evolution of anaesthesia having the benefit of new drugs and devices, and the rationale for using muscle relaxants balanced against their potential side-effects and possible pharmacodynamic alterations in neurosurgical patients.

Anesthesia, General↗

PubMed2003

Effect of intra-operative magnesium sulphate on pain relief and patient comfort after major lumbar orthopaedic surgery.

The effects of intra-operative magnesium sulphate on pain relief after major lumbar surgery were investigated in 24 patients. Patients were randomly allocated to receive either an infusion of 50 mg x kg(-1) magnesium sulphate or an equivalent volume of saline at induction of anaesthesia. Anaesthesia was induced with propofol and remifentanil. Tracheal intubation was facilitated using rocuronium. Maintenance was achieved with remifentanil and sevoflurane in nitrous oxide/ oxygen. Intra-operative monitoring included standard equipment and neuromuscular transmission. During surgery, neuromuscular block recovery was longer in the magnesium group. Postoperative opioid consumption and pain scores were lower in the magnesium group. The first night's sleep and the global satisfaction scores were better in the magnesium group. The results of the study support magnesium sulphate as a useful adjuvant for postoperative analgesia after major lumbar surgery.

Adult↗

PubMed2002

[Perioperative management of blood loss during surgical treatment for craniosynostosis].

Blood saving is the major challenge during the surgical repair of craniofacial deformities. Treated patients have a low reserve volume and the techniques available to lower homologous blood transfusions are limited or insufficiently evaluated in this particular case. The most important factor determining blood loss is the quality of the surgical haemostasis. Blood saving begins with early preoperative evaluation of the patient's bleeding risk, which is a function of the type of surgery, of the surgical technique, of the number of sutures involved, of the length of surgery, and of the patients age, weight and physical status. Elaborated blood saving techniques such as preoperative autologous blood donation, erythropoietin administration, normovolaemic haemodilution, and peroperative autologous blood saving and reinfusion have revealed disappointing where used alone. These techniques require a heavy setup and still need to be evaluated extensively. They should be used in selected cases such as in patients with a very high risk of bleeding or face to Jehovah Witnesses. Monitoring during surgery should include precise evaluation of blood losses and haematocrit measurements at regular intervals. The haematocrit threshold allowing homologous blood transfusion should be set at 21%, provided that any other source of autologous blood is exhausted. Postoperative monitoring should also include precise evaluation of blood losses and haematocrit measurements. The 21% threshold should remain the reference during that period.

Blood Loss, Surgical↗

PubMed2002

[How I treat ... facial paralysis by hypoglosso-facial anastomosis].

Thirteen patients underwent a hypoglosso- or a spino-facial nerve anastomosis between 1990 and 1996. Facial palsy was the result of surgery in 12 cases and of radiosurgery in 1 case. The mean interval between facial palsy and anastomosis was 12 months. Facial nerve function is determined on the basis of clinical examination according to the classification of House-Brackmann and our own evaluation. According to House, 10 patients are classified grade III and 3 grade IV. Our evaluation defines in 10 grade III, 7 good results and 3 fair results. As far as the good results are concerned, the mean interval between palsy and anastomosis is short (< 3 months). The permanent eating and swallowing dysfunctions are consecutive to multiple cranial nerve deficits. The post-paralysis hemifacial spasm is facilitated by prolongated electric stimulations.

Adult↗

PubMed2002

[Arterial aneurysm within a tumor in a pediatric patient].

A middle cerebral artery aneurysm, completely enclosed in a large frontotemporal anaplastic astrocytoma, is demonstrated in a 11-month-old girl admitted for intracranial hypertension. Clipping of the aneurysm along with radical resection was successfully performed. Five years later, follow-up neurological examination is normal, aneurysm occlusion and no evidence of tumor recurrence are demonstrated by angiogram and MRI. The association of brain tumor and aneurysm is discussed, and documented with the only two cases of a neoplasm surrounding on aneurysm reported in the literature.

Astrocytoma↗

PubMed2001

[Hypernatremia in neurosurgical pathology].

Hypernatraemia is defined as an increase in extracellular sodium concentration, associated with plasma hyperosmolality and cellular dehydration. It can result from excessive water loss, from an increase in the total sodium content or from both mechanisms. As far as neurosurgical pathology is concerned, hypernatraemia due to excessive water loss may be observed in patients who do not sense thirst or are unable to ingest water. Urinary water loss is seen in diabetes insipidus and osmotic diuresis. Extrarenal water losses from pulmonary origin may be observed in intubated or tracheotomized patients. Hypernatraemia with sodium and water retention may be encountered in patients suffering from Cushing diseases or syndromes, or more frequently in those who are given excessive amounts of sodium (hypertonic saline, sodium salts). Clinical manifestations of hypernatraemia consist of neurologic symptoms related to cellular dehydration; their severity is correlated with the rapidity of the onset of the electrolytic disorder. Depending on the pathophysiological mechanism, treatment of hypernatraemia involves stopping sodium intake, restoring normovolaemia and administering hypotonic fluids. Treatment of diabetes insipidus relies on the administration of the antidiuretic hormone and of drugs that increase its secretion rate or its responsiveness in the kidneys.

Diabetes Insipidus↗

PubMed2001

Effect of nitrous oxide on the bispectral index and the 95% spectral edge frequency of the electroencephalogram during surgery.

We studied the effect of nitrous oxide on the bispectral index and 95% spectral edge frequency of the electroencephalogram in 20 patients undergoing lumbar surgery under general anaesthesia combined with epidural administration of 5 mg morphine. Anaesthesia was induced with propofol and sufentanil, and maintained with sevoflurane in air/oxygen adjusted to keep the bispectral index between 40 and 60. One and a half hours after the start of surgery, nitrous oxide was administered in a randomised sequence of concentrations (20, 40 and 60% end-expired). Under steady-state conditions, mean (SD) bispectral index and spectral edge frequency decreased as end-tidal concentration of nitrous oxide increased, from 47.7 (4.3) and 15.6 (1.3) at 0% nitrous oxide to 39.8 (6.3) and 14.3 (1.8) at 60% nitrous oxide. A negative correlation was found between nitrous oxide concentration and bispectral index (r = -0.48; p < 0.01) and spectral edge frequency (r = -0.39; p < 0.05). We conclude that this dose-dependent decrease in bispectral index and spectral edge frequency induced by nitrous oxide may reflect the level of analgesia associated with the anaesthetic regimen.

Adult↗