Electrical modulation of neuronal networks in brain-injured patients with disorders of consciousness: a systematic review.

Six clinical studies of chronic electrical modulation of deep brain circuits published between 1968 and 2010 have reported effects in 55 vegetative or minimally conscious patients. The rationale stimulation was to activate the cortex through the reticular-thalamic complex, comprising the tegmental ascending reticular activating system and its thalamic targets. The most frequent intended target was the central intralaminar zone and adjacent nuclei. Hassler et al. also proposed to modulate the pallidum as part of the arousal and wakefulness system. Stimulation frequency varied from 8Hz to 250Hz. Most patients improved, although in a limited way. Schiff et al. found correlations between central thalamus stimulation and arousal and conscious behaviours. Other treatments that have offered some clinical benefit include drugs, repetitive magnetic transcranial stimulation, median nerve stimulation, stimulation of dorsal column of the upper cervical spinal cord, and stimulation of the fronto-parietal cortex. No one treatment has emerged as a gold standard for practice, which is why clinical trials are still on-going. Further clinical studies are needed to decipher the altered dynamics of neuronal network circuits in patients suffering from severe disorders of consciousness as a step towards novel therapeutic strategies.

[Resuscitation after three hours of cardiac arrest with severe hypothermia following a toxic coma]. / Récupération sans séquelle après trois heures d'arrêt cardiaque en hypothermie à 22 degrees C au décours d'un coma toxique.

We report the case of a 37-year-old woman who survived from severe hypothermia (rectal temperature: 22 degrees C) and prolonged cardiac arrest with asystole after benzodiazepine and tricyclic antidepressant poisoning. Basic-cardiopulmonary resuscitation and mechanical ventilation was started by a French Mobile Intensive-Care unit. Spontaneous circulation was restored at 25 degrees C under epinephrin after three hours of chest compression from home to the intensive-care unit and rewarming with extracorporeal circulation. The patient was discharged at day 13 without any neurological deficit. The discussion focuses on the benefit of extracorporeal-membrane oxygenation (ECMO) as extracorporeal circulation device through femoral access, the differential diagnosis between death and recoverable cardiac arrest and neuroprotection.

Comparison of tolerance of facemask vs. mouthpiece for non-invasive ventilation.

This prospective, single centre, randomised, cross-over study compares patient tolerance of the facemask and mouthpiece for delivery of non-invasive ventilation in an intensive care unit. Twenty-seven patients with acute respiratory failure were scheduled for two 45-min sessions of non-invasive ventilation with facemask and mouthpiece. The order of the sessions was chosen at random. Nurses and patients assessed the tolerance of both techniques using a visual analogue scale. The time spent by nurses and the changes in respiratory parameters were recorded. The facemask was better tolerated than the mouthpiece; all the cases of non-invasive ventilation withdrawal (n = 5) occurred with mouthpieces (p = 0.026). Less nursing time was required using the facemask for the 22 patients who underwent both procedures (p = 0.01). However, the difference in tolerance scores was not significant. Non-invasive ventilation with both facemask and mouthpiece improved the P(a)o(2)/F(i)o(2) ratio, increased the pH and decreased the P(a)co(2). Only non-invasive ventilation with the facemask lowered the respiratory rate. The facemask appears to be a better initial choice for non-invasive ventilation when compared to mouthpiece, but both can be effective.

[Effect of bronchial drainage on the improvement in gas exchange observed in ventral decubitus in ARDS]. / Influence du drainage bronchique dans l'amélioration des échanges gazeux observée en décubitus ventral au cours du SDRA.

OBJECTIVES: A bronchial secretion draining effect is frequently suggested as a mechanism for oxygenation improvement during prone positioning (PP) in patients with acute respiratory distress syndrome (ARDS). Nevertheless, it has never really been evaluated. The aim of this study was to search for an interrelationship between the volume of the bronchial secretion and the improvement of the PaO2/FIO2 ratio during prone positioning, with NO inhalation or not. STUDY DESIGN: Open prospective clinical study. PATIENTS: The study included 15 consecutive patients with severe ARDS (PaO2/FIO2 < 200 after alveolar recruitment, Murray score > 2.5). METHODS: They were returned to the prone position for 4 hours (h0-h4) combined with an inhalation of 5 ppm NO during 1 hour (h2-h3). Tracheal suction were performed hourly between h-2 and h6 and weighed on a precision scale from h-1 to h6. Haemodynamic, blood gas and respiratory compliance were recorded at h0, h2, h3, h4 and h6. RESULTS: No significant haemodynamic changes were observed in the various phases. Compared with the baseline condition at h0, PP and PP + NO respectively improved PaO2/FIO2 by 102 +/- 62% at h2 (P < 0.005) and 156 +/- 79% at h3 (P < 0.005/h0 and < 0.01/h2). 14/15 patients responded to PP and 15/15 to PP + NO (gain in PaO2/FIO2 > 10%). Concerning secretions, we collected 3.0 +/- 7.5 g, 4.4 +/- 6.1 g, 1.7 +/- 1.4 g and 1.7 +/- 1.6 between h-2 and h0, h0 and h2, h2 and h4, h4 and h6. Individual assessments showed no relationship between the PaO2/FIO2 evolution at any time and the quantity of secretions obtained during the first 2 hours in the prone position. Six patients presented secretions of less than 1 g between h0 and h2, and for whom the improvement in oxygenation was higher than average (115 +/- 53% at h2). CONCLUSION: In patients with little or moderate secretions, the improvement observed in oxygenation, with or without NO, does not depend on their volume.

Lidocaine plus ropivacaine versus lidocaine plus bupivacaine for peribulbar anesthesia by single medical injection.

UNLABELLED: This study was designed to compare the effects of ropivacaine and bupivacaine, each combined with lidocaine, during peribulbar anesthesia by single medial injection for cataract surgery. One hundred patients were included and randomly divided into two groups of 50, given a mixture of 50% bupivacaine (0.5%) and 50% lidocaine (2%) or 50% ropivacaine (1%) and 50% lidocaine (2%), and 25 U hyaluronidase per mL with each combination. After the first injection, patients given ropivacaine exhibited significantly better akinesia than those given bupivacaine, and significantly fewer were reinjected (19/50 vs 31/50). Among the patients reinjected, peroperative akinesia and analgesia proved satisfactory in both groups. We observed three cases of diplopia caused by retraction of the internal rectus muscle and two cases of moderate ptosis after superonasal reinjection. Hemodynamic profiles were similar in the two groups, and no major side effects were noted during the observation. One percent ropivacaine may be a more appropriate agent than 0.5% bupivacaine for peribulbar anesthesia by single medial injection. IMPLICATIONS: One percent ropivacaine may be a more appropriate agent than 0.5% bupivacaine for peribulbar anesthesia by single medial injection. Combined with lidocaine, it provides better akinesia and similar analgesia.

The effects of volume and speed of injection in peribulbar anaesthesia.

We have evaluated the effects of the volume and speed of administration of local anaesthetic during peribulbar anaesthesia. One hundred and forty patients scheduled for cataract surgery were randomly allocated to one of four groups of 35. Each patient received an injection of the same mixture of lignocaine, bupivacaine and hyaluronidase. Patients in group A were given 9 ml at a speed of 5 ml.min-1, group B were given the same volume at 12 ml.min-1, group C were given 13.5 ml at 5 ml.min-1 and group D were given 13.5 ml at 12 ml.min-1. A significantly higher incidence of satisfactory akinesia was found in group D, whose pain score at injection was no higher than for the other groups. Large volumes of local anaesthetic significantly affected intra-ocular pressure. The incidences of early and late ptosis or diplopia were not affected by either the rate of injection or the volume of local anaesthetic.

Combined nitric oxide inhalation, prone positioning and almitrine infusion improve oxygenation in severe ARDS.

PURPOSE: To determine the efficacy and side effects of prone positioning (PP) and nitric oxide (NO) inhalation, alone, associated, or combined with i.v. almitrine for the treatment of hypoxaemia in severe acute respiratory distress syndrome (ARDS). METHODS: Over a period of 20 months, 27 consecutive critically ill patients with severe ARDS (Murray score > 2.5, PaO2/FiO2 < 170 after alveolar recruitment) were prospectively and randomly included. They inhaled NO for two hours at concentrations of 5 and 10 ppm for one hour each (H0-H2). One hour later, they were returned to the prone position for four hours (H3-H7). During the last two hours in this position (H5-H7), they were assigned to further inhalation of 10 ppm NO (Group B, n = 9) or to no further inhalation (Group A, n = 9). In group C (n = 9), the procedure for group B was combined with perfusion of 16 mg.kg-1.min-1 almitrine throughout the study. RESULTS: Compared with control values, two hours NO inhalation improves PaO2/FiO2 and shunt effect by +28% and -9%, PP by +88% and -27%, PP + almitrine by +132% and -28%, NO + almitrine by +153 and -28%, PP + NO by +94% and -29%, NO + PP + almitrine by +327 and -48%. NO inhalation reduces pulmonary vascular resistance. Other haemodynamic parameters remain unchanged, whatever the treatment. NO inhalation improves PaO2/FiO2 by over 20% in 50% of the patients and PP is effective in 78% of the cases. CONCLUSION: Prone Position improves PaO2/FiO2 significantly more than NO alone but less than PP + almitrine or NO + almitrine. The best results are obtained with the association of NO + Prone position + Almitrine.

Haemodynamic conditions enhancing gas embolism after venous injury during laparoscopy: a study in pigs.

This study was designed to determine the conditions that promote carbon dioxide embolism after venous injury during laparoscopy in pigs. Injury to an iliac vein was filmed during laparoscopy in the presence of a pneumoperitoneum created at increasing pressures from 0 to 30 mm Hg in 5-mm Hg increments. At intraperitoneal pressures less than 20 mm Hg, there was a parallel increase in femoral venous pressures, resulting in haemorrhage, with persistent blood flow to the inferior vena cava. At intraperitoneal pressures of 20-30 mm Hg, there was collapse of the femoral vein, occurring earlier in the presence of hypovolaemia. Between these two states (haemorrhage and collapse), there was a point of equilibrium which allowed retrograde venous penetration of carbon dioxide bubbles. During release of the pneumoperitoneum, these bubbles were exteriorized through the area of the injury, but some passed into the inferior vena cava where their presence was detected by an oesophageal Doppler probe.

Effect of injection pressure on the success rate of peribulbar block.

The aim of this prospective double-blind study was to evaluate the effect of the pressure on injection of local anaesthetic during peribulbar anaesthesia. Fifty patients scheduled for cataract surgery under peribulbar anaesthesia, with a two injection site technique, were randomly assigned to receive a mixture of 5 ml of etidocaine 1%, 4 ml of bupivacaine 0.5% and hyaluronidase 50 IU, injected under a constant pressure of either 140 g.cm-2 (group 1) or 250 g.cm-2 (group 2). After orbital compression, the degree of akinesia of the extra-ocular and orbicular muscles was graded by clinical assessment. A significantly higher rate of satisfactory akinesia of the extra-ocular muscles was found in group 2 (72% vs 28% in group 1) (p < 0.01). No significant relationship was found between the time taken to administer the anaesthetic mixture at constant pressure and the quality of the block.

Pulmonary interstitial edema after probable carbon dioxide embolism during laparoscopy.

Carbon dioxide embolism is a well-known complication of laparoscopy that can be lethal. We describe a patient who showed signs of pulmonary interstitial edema revealing a probable gas embolism. This event occurred during a gynecologic laparoscopy performed for uterine perforation after a curettage.