[Spectral analysis of the ECG R-R interval permits early detection of vagal responses to neurosurgical stimuli]. / L'analyse spectrale de l'intervalle R-R de l'ECG permet la détection précoce des réponses vagales aux stimuli neurochirurgicaux.

OBJECTIVE: To assess the efficacy of ECG spectral analysis, compared with heart rate (HR) monitoring in the detection of vagal response to surgical stimuli. METHODS: Twenty Asa II-III patients (age: 65 +/- 13 years) scheduled for surgery of cerebellopontine angle or implantation of sacral root stimulator were examined. Target controlled infusion of propofol (2-4 microg x ml(-1)) and remifentanil (4 ng x ml(-1)) was guided by the bispectral index (Bis). Arterial pressure via a radial catheter, pulse oximetry and end tidal CO2 were continuously monitored. Spectral analysis was achieved by connecting a computer to the cardiorespiratory monitor. Online power spectrum densities were calculated from the ECG R-R interval by software based on the fast Fourier transform (LabView, National Instruments, USA). Low frequency (LF: 0.04-0.15Hz) and high frequency (HF: 0.15-0.4Hz) were associated with sympathetic and parasympathetic activities respectively. We defined vagal reaction as a decrease in FC or an increase in HF >10% of the prestimuli value. HF and FC were compared according to the detection delay (by a Student t test with p < 0.05 considered significant) and a concordance test with a kappa coefficient (kappa): -1 = total discordance to 1 = total concordance. RESULTS: Twelve vagal reactions (observed in 8 patients) were detected within 5.5 +/- 1.3 s (HF) and 12.4 +/- 1.6 (FC); p < 0.001. Concordance between the 2 parameters was 95% (kappa =0.9). CONCLUSION: The ECG spectral analysis is a non-invasive technique, which permits the detection of intra-operative vagal reactions earlier than conventional monitoring of HR.

[Cerebrospinal fluid shunting: anesthetic particularities]. / Les dérivations du liquide céphalorachidien: particularités anesthésiques.

The symptomatic treatment of hydrocephalus remains cerebrospinal fluid (CSF) drainage to an external reservoir (external CSF drainage) or to an internal cavity mainly the peritoneum or the right atrium via a unidirectional valve (internal CSF drainage) and finally by endoscopic ventriculocisternostomy. Local anaesthesia is adequate for external CSF drainage in adults and children above 10 years while general anaesthesia is required in all other cases. The main problems encountered in these patients are difficult intubation and full stomach associated with increased intracranial pressure. The anaesthetic approach should favour homeostasis. With the exception of ketamine and enflurane, the majority of anaesthetic drugs can be used. Anti-epileptic drug are mandatory. Antibioprophylaxis mainly against staphylococcus is systematic in internal CSF drainage. Rapid emergence from anaesthesia and extubation should be encouraged. Complications (infectious, mechanical and bleeding kinds) are frequent and are often the cause of reinterventions or revisions of the device, exposing the patients to iterative anaesthesia. Furthermore, patients with shunts are at risk of malfunction of the device when exposed to situations like pregnancy, magnetic resonance imaging, or laparoscopy. Under these circumstances, it is recommended to associate the neurosurgical team in the management of these patients and to verify that the shunt is working well before and after the procedure or event.

[Untreatable ventricular hemorrhage revealing cerebral metastasis of malignant melanoma]. / Hémorragie intraventriculaire incoercible révélatrice d'une métastase cérébrale d'un mélanome malin.

High levels of tissue-like plasminogen activator in cerebrospinal fluid reported in a patient with an intracerebral haemorrhage associated to cerebral metastasis of malignant melanoma could support the hypothesis of cerebral haemorrhage induced by tPA tumoral synthesis.

Dynamic cardiomyoplasty in a growing organism.

BACKGROUND: Until now cardiomyoplasty has been a treatment option for adults only. However, there may be a demand for cardiomyoplasty in children. The purpose of this study was to investigate the possibility of applying the method of cardiomyoplasty before growth is completed. METHODS: The latissimus dorsi muscle (LD) was wrapped around the heart of 20 Göttinger Minipigs (9.1 +/- 1.2 kg body weight). The LD was fixed to the pericardium in group 1 (n = 11) and to the epimyocardium in group 2 (n = 9) and stimulated with burst impulses. After 5.6 +/- 1.8 months hemodynamic and histologic follow-up-examinations were carried out in 13 surviving animals (weight 32.4 +/- 5.3 kg). RESULTS: In group 1 (n = 6) only the left ventricle was covered by the LD. In 4 animals the LD contracted strongly; in 2, the outer border of the muscle was atrophied. In group 2 (n = 7) both ventricles were covered by the LD in all animals and showed strong contractions. In 2 animals the outer border of the muscle was atrophied. In both groups the contracting parts of the LD showed an intact muscle structure, but compared with the contralateral LD, there was a higher percentage of interstitial fat and connective tissue. Hemodynamic measurements and the well-being of the animals suggest that restriction of cardiac chamber diameter did not occur. The electrical stimulation of the LD caused a minimal increase of left ventricular pressure and aortic peak flow in group 2. CONCLUSIONS: Cardiomyoplasty can be applied in a growing organism. There is growth of the LD with the heart. The muscle structure remains intact. To prevent dislocation of the LD, it seems to be important to fix the LD directly onto the epimyocardium.

[Value of hypovolemia in subarachnoid hemorrhage]. / Importance de l'hypovolémie au cours des hémorragies sous-arachnoidiennes.

Hypovolemia seems a commun state in patients with subarachnoid hemorrhage. It has been further suggested that hypovolemia could cause ischemia if vasospasm is present. Total blood volume and red blood cells volume determined in 84 consecutive patients volume of distribution (of 51Chromium labeled autologous red cells, shows an hypovolemia in 70% of these patients). Associated hypomotremia requires Na restitution with normovolemic hemodilution to facilitate cerebral blood flow.