[Brain perfusion and metabolism imaging techniques]. / Imagerie de la perfusion et du métabolisme cérébral.

Due to recent efforts in improving spatial and temporal resolution in imaging techniques, it is now possible to get relevant information about brain perfusion and metabolism in humans. This information can significantly impact on brain pathophysiology, diagnosis assessment and therapy options, particularly in patients having brain ischemia. Among these imaging and metabolism techniques are dynamic perfusion computed tomography, perfusion MRI, positron emission tomography and NMR spectroscopic imaging. The goal of this article is an overview of these four techniques, with their own technical description, advantages and drawbacks. Details are provided about brain parameters given by each technique and their clinical relevance, the accessibility of the technique in the emergency setting and the optimal window to use it during the patient's evolution.

[Contribution of magnetic resonance spectroscopy in predicting severity and outcome in traumatic brain injury]. / Apport de la spectroscopie RMN à l'évaluation du traumatisme crânien.

Nuclear magnetic spectroscopy (MRS) is a useful method for noninvasively studying intracerebral metabolism. Proton MRS can identify markers of the neuronal viability (N-acetyl-aspartate, NAA), of the metabolism of cellular membranes (choline), of the cellular energy metabolism (creatine, lactate). In Phosphorus MRS, the peaks most readily identified are involved in the high-energy cellular metabolism (ATP, phosphocreatine, inorganic phosphate), and intracellular pH (pHi) can be determined using this method. MRS has been used in experimental models of traumatic brain injury (TBI), primarily to study the cellular metabolism and the relation between biochemical and histological changes after trauma. In trauma patients, significant changes in NAA, choline and pHi were found in both grey and white matter comparing with controls, and these alterations correlated with injury severity. Correlations have been reported between these biochemical changes (reduction in NAA, increase in choline) measured at 1 to 6 months after TBI and the clinical outcome of the patients. However, there are methodological issues which still impede to recommend MRS as a tool for predicting neurological outcome in the clinical setting.

Systemic vasomotor interaction between nicardipine and hypocapnic alkalosis in man.

The effects of hypocapnic alkalosis on the vasodilating action of nicardipine were studied in 6 patients after cerebral arterial aneurysm surgery. Each patient served as his/her own control during the 6 steps of the study. T0: baseline; T1: hypocapnic alkalosis alone (PaCO2: 3.5 kPa); T2: hypocapnic alkalosis and bolus injection of nicardipine (30 micrograms.kg-1 i.v.); T3: hypocapnic alkalosis and continuous 60 min infusion of nicardipine (0.5 microgram.kg-1.min-1), T4: determination of the infusion rate required to neutralize the effect of hypocapnic alkalosis; T5: same continuous dose of nicardipine as in T4 but reversal of hypocapnic alkalosis. Hypocapnic alkalosis alone caused a significant increase in the systemic vascular resistance index by 20% (T1). The bolus injection of nicardipine reversed this first effect (T2). The continuous infusion of nicardipine in T3 was insufficient to cancel the haemodynamic effect of hypocapnic alkalosis. During T4 the plasma levels required to neutralize completely the effect of hypocapnic alkalosis were twice those at T3. Normalization of the PaCO2 in step T5 induced a significant fall in the systemic vascular resistance index by 27.5% as compared with T0. In this study hypocapnic alkalosis modified the relationship between plasma levels of nicardipine and its expected vasoactive effects. This interaction was reversible.

Nosocomial pneumonia in mechanically ventilated patients, a prospective randomised evaluation of the Stericath closed suctioning system.

OBJECTIVE: To compare the ventilator-associated pneumonia (VAP) incidence rates in mechanically ventilated patients according to the type of endotracheal suctioning (closed versus open). SETTING: The Neurosurgery Intensive Care Unit of the Grenoble University Hospital, France. DESIGN: A prospective randomised study performed after a 6-month period of nursing personnel training. PATIENTS: One hundred four consecutive patients needing mechanical ventilation for more than 48 h were randomised into two groups. To be eligible, patients had to have no active infection or respiratory affection in their passes. In the Stericath group (S+, n = 54), patients were not disconnected from the ventilator during suctioning. The others were routinely managed (S-, n = 50). In both groups patterns of frequency and duration of suctioning were performed according to a standardised protocol. MEASUREMENTS: The non-adjusted incidence rate of VAP was lower for S+ than for S- (7.32 versus 15.89 per 1000 patient-days, p = 0.07). Multivariate analysis performed using the Cox model showed an adjusted risk of VAP 3.5 times higher in S- (95% CI: 11.00-12.33). The risk being 4.3 higher in patients receiving gastric acid secretion inhibitors (1.08-16.82). In non-censored cases (n = 76) length of ICU stay increased by an average of 16.8 days when VAP was present (p = 0.0008). No adverse effect due to Stericath use was noted and volume of tracheal aspirate was similar between groups (p = 0.178). CONCLUSION: The use of Stericath reduced the incidence rate of VAP without demonstrating any adverse effect.

Severe head injuries: an outcome prediction and survival analysis.

OBJECTIVE: To identify the predictors determined early after admission and associated with unfavorable outcome or early (within 48 h) death after severe head injury. DESIGN: Prospective cohort study. SETTING: A neurosurgical intensive care unit in a university hospital. PATIENTS: 198 consecutive comatose patients hospitalized from 1989 to 1992. RESULTS: Logistic regression showed that a combination of age, best motor response score from the Glasgow Coma Scale, and hypoxia provided a good prediction model of unfavorable outcome (sensitivity = 0.93). The length of participation of survivors was 6 to 61 months (median 27.1). The Cox model demonstrated age, motor score less than 3, mydriasis, and hypoxia as poor prognosis factors. CONCLUSIONS: Clinicians can determine the odds of a good outcome from the combination of three easily measurable factors using a simple diagram constructed from logistic regression. Survival analysis showed that motor score adjusted values greater than 3 had the same prognosis.

[Axillary-subclavian injuries. Apropos of 11 cases. Procedural problems]. / Les traumatismes axillo-sous-claviers. A propos de 11 observations. Problèmes tactiques.

Tactical problems raised by treatment of injuries involving the axillary-subclavicular region were studied by analysis of 11 cases treated in a Grenoble hospital since 1975. The majority of patients had multiple injuries, and it was possible to perform pre-operative angiography in all cases. Lesions involving the mobile post-vertebral segment of the subclavian artery were treated by pre-sternocleidomastoid cervicotomy through a deltopectoral approach enlarged in L. Functional prognosis was related to the frequency and severity of associated neurological lesions.

[Four cases of tracheoesophageal fistulas in adults in intensive care units]. / Quatre cas de fistules oeso-trachéales chez l'adulte en réanimation.

Four cases of tracheo-oesophageal fistulae following mechanical ventilation are reported. The determining factors, revealing signs, and palliative and curative treatment are discussed based on a review of the literature. In this series, the tracheotomy cannula provided good protection of the upper airways in three cases of upper fistulae. In the other case, the fistula was too close to the carena, requiring the use of high frequency jet ventilation. The management of low, large fistulae is more problematic concerning the choice of technique and timing of the operation.

[Brain oedema following blood-brain barrier disruption: mechanisms and diagnosis]. / Oedème cérébral par lésion de la barrière hématoencéphalique: mécanismes et diagnostic.

Brain oedema following blood-brain barrier (BBB) disruption, or vasogenic oedema, is present in most cases of brain oedema. According to the Starling's law, water, ions and plasma proteins cross the BBB toward the interstitium if the driving forces for transmural bulk flow are excessive (mechanical origin) and/or if the BBB permeability is enhanced (chemical origin). Both mechanisms coexist in most cases. Excessive elevation of the gradient of hydrostatic pressure with lost of cerebral autoregulation has been proved in ischaemia/reperfusion and trauma, and suggested in acute mountain sickness and eclampsia. The BBB permeability can be enhanced by immediate (chemical mediators) or delayed (cellular infiltration) inflammatory response, or by alteration of the membrane integrity. This later can be transient (hyperosmolar BBB disruption), or permanent by activation of matrix metalloproteinase or by neovascularization with BBB breakdown. The reference method for the diagnosis of vasogenic oedema is the MRI diffusion-weighted imaging.

[Peripheral venous catheterization: influence of catheter composition on the occurrence of thrombophlebitis]. / Cathétérisme veineux périphérique: influence de la composition du cathéter dans l'apparition de thrombophlébites.

Infusion thrombophlebitis is a common troublesome complication of intravenous therapy. This study compared peripheral intravenous Teflon and Vialon catheters. The incidence of phlebitis, bacterial adherence and mechanical resistance (distortion) were assessed on 170 catheters, 85 of each type. The Vialon catheter resulted in less phlebitis than the Teflon one (18 vs. 35; p less than 0.01). During the period 49 to 72 h after the insertion of the catheter, the risk of phlebitis in the Teflon group was twice that in the Vialon group. The study of bacterial adherence using a semi-quantitative culture method demonstrated that 9.0% of the catheters were infected with Staphylococcus epidermidis. There was no statistically significant difference between the two groups (5.7% Vialon group vs. 12.5% Teflon group). The Teflon catheters were much more distorted than vialon catheters: 1.7% vs. 55.7% in the macroscopic study; 1.75% vs. 8.2% in the microscopic study. As Vialon softens at body temperature, it would seem likely that it generates a lesser degree of endothelial injury, explaining the lower rate of phlebitis with Vialon catheters.

[A protocol for the cessation of sedation in brain-injured patients]. / Évaluation d'un protocole d'arrêt de la sédation chez le patient cérébrolésé

OBJECTIVES: The cessation of sedation in brain-injured patients may result in severe agitation and/or acute withdrawal syndrome related to the prolonged administration of large doses of benzodiazepines and/or opioids. The aim of the present study was to assess the clinical efficacy of a written protocol to withdraw sedation for these patients. STUDY DESIGN: Observational prospective study. PATIENTS AND METHODS: After approval by the Institutional Review Board, 40 severely brain-injured patients were included. They had received continuous administration of midazolam and sufentanil or fentanyl for median 15 days. On cessation of midazolam infusion, patients were given clorazepate for 3 days. On cessation of opioid infusion and clorazepate, clinical data were collected for 48 hours: heart rate, systolic blood pressure, respiratory rate, agitation, and pupil diameter. If an opioid withdrawal syndrome occurred, patients received a 48-hour continuous infusion of buprenorphine. RESULTS: Of 40 patients, there were 10 who did not require buprenorphine. An agitation occurred 5 hours (1-21) after cessation of opioid, associated with tachycardia, arterial hypertension, and tachypnea. After 6 hours buprenorphine treatment, these parameters were normalized. No patient needed the reintroduction of the initial sedation. CONCLUSION: The cessation of sedation in severely brain-injured patients can be successfully managed with the use of clorazepate, associated with buprenorphine in the presence of agitation.

[Sedation in neurointensive care unit]. / Neurosédation en réanimation.

The objectives for using sedation in neurointensive care unit (neuroICU) are somewhat different from those used for patients without severe brain injuries. One goal is to clinically reassess the neurological function following the initial brain insult in order to define subsequent strategies for diagnosis and treatment. Another goal is to prevent severely injured brain from additional aggravation of cerebral blood perfusion and intracranial pressure. Depending on these situations is the choice of sedatives and analgesics: short-term agents, e.g., remifentanil, if a timely neurological reassessment is required, long-term agents, e.g., midazolam and sufentanil, as part of the treatment for elevated intracranial pressure. In that situation, a multimodal monitoring is needed to overcome the lack of clinical monitoring, including repeated measurements of intracranial pressure, blood flow velocities (transcranial Doppler), cerebral oxygenation (brain tissue oxygen tension), and brain imaging. The ultimate stop of neurosedation can distinguish between no consciousness and an alteration of arousing in brain-injured patients. During this period, an elevation of intracranial pressure is usual, and should not always result in reintroducing the neurosedation.

[Long-term outcome of patients after aneurysmal SAH]. / Devenir à long terme des patients après une HSA anévrismale.

Adequate instruments for measuring patient outcome after subarachnoid aneurysmal haemorrhage (SAH) are required to interpret results of clinical trials before making clinical recommendations. Graded measures are generally used, e.g. Glasgow Outcome Scale (GOS) and the modified Rankin Scale (mRS). However, these scales are inappropriate to measure cognitive dysfunction, particularly in patients with good outcome. We investigated the most frequent complains, the working status and the self-assessment of handicap (quality of life) in GOS-5 patients after their surgical treatment of a ruptured aneurysm. A questionnaire was sent to 126 patients one year following their discharge from hospital. The questionnaire assessed their motor activity, vitality and psychological troubles and handicap. Over 84 patients with GOS-5, 55 (65%) had persistent cognitive and psychological troubles including memory deficit, vitality and depressive troubles. Providing the use of combined scales to assess handicap and quality of life, these results suggest that SAH can result in a persistent alteration of cognitive function in patients, even in those classified as having a good outcome using the routine graded scales.

Combined effects of hypocapnia and nicardipine on airway resistance: a pilot study.

OBJECTIVE: The aim of this study was to investigate the modification of the resistive inspiratory properties of the respiratory system associated with hypocapnia in the presence of nicardipine. METHODS: The resistance of the respiratory system, Rrsmin, was studied in two groups of patients who needed mechanical hyperventilation. Group 1 (n = 14; 47 years) was the control group (head injuries); group 2 (n = 12; 53.5 years) included patients treated over a 3 week period with nicardipine (0.5 microgram.kg-1.min-1 i.v.) to prevent arterial vasospasm after subarachnoid haemorrhage. RESULTS: There was no statistical difference between the groups concerning anthropometric and basal respiratory characteristics. In group 1, hypocapnia caused a 20.9% increase in Rrsmin, but no significant increase was observed in group 2. CONCLUSION: Hypocapnic alkalosis had a significant bronchial constrictory effect, which was eliminated in the presence of nicardipine hydrochloride.