Validation of Davson's equation in patients suffering from idiopathic normal pressure hydrocephalus.

INTRODUCTION: The so-called Davson's equation relates baseline intracranial pressure (ICP) to resistance to cerebrospinal fluid outflow (Rout), formation of cerebrospinal fluid (If) and sagittal sinus pressure (PSS) There is a controversy over whether this fundamental equation is applicable in patients with normal pressure hydrocephalus (NPH). We investigated the relationship between Rout and ICP and also other compensatory, clinical and demographic parameters in NPH patients. METHOD: We carried out a retrospective study of 229 patients with primary NPH who had undergone constant-rate infusion studies in our hospital. Data was recorded and processed using ICM+ software. Relationships between variables were sought by calculating Pearson product correlation coefficients and p values. RESULTS: We found a significant, albeit weak, relationship between ICP and Rout (R = 0.17, p = 0.0049), Rout and peak-to-peak amplitude of ICP (AMP) (R = 0.27, p = 3.577e-05) and Rout and age (R = 0.16, p = 0.01306). CONCLUSIONS: The relationship found between ICP and Rout provides indirect evidence to support disturbed Cerebrospinal fluid circulation as a key factor in disturbed CSF dynamics in NPH. Weak correlation may indicate that other factors-variable PSS and formation of CSF outflow-contribute heavily to linear model expressed by Davson's equation

Étude de l'impact des variations de capnie sur la microcirculation chez le patient réalisant un test d'hypercapnie

Introduction: La restauration de la perfusion tissulaire est un enjeu majeur de la réanimation. La microcirculation participe très largement à maintenir l'oxygénation tissulaire. Ces déterminants connus sont, la macrocirculation (PAM et DC) et l'état de cette microcirculation (thrombose, vasoconstriction...). Une étude précédemment réalisée dans le service de réanimation cardiaque, nous laisse penser que le CO2 a un effet propre sur la régulation du débit microcirculatoire. Le but de notre étude est d'évaluer l'impact des variations de la capnie sur le débit microcirculatoire. Matériel et Méthodes: 15 patients, à microcirculation saine, venant réaliser un test d'hypercapnie ont été inclus dans notre étude, après le recueil de leur consentement. Le débit microcirculatoire a été analysé grâce à la microscopie confocale, la NIRS, le laser doppler et le gradient veino-artériel en CO2. L'étude de la microcirculation a été faite lors de 4 temps (basal 1, hypo/hvpercapnie, basal 2 puis hyper/hypocapnie) après randomisation des épreuves d'hypo et d'hypercapnie. L'hypercapnie était obtenue par l inhalation d'un mélange gazeux enrichi en CO2 à 7 %. Tandis que, l hypocapnie était obtenue par une hyperventilation en air ambiant. Résultats: La réalisation d'épreuves d hypocapnie et d'hypercapnie chez15 sujets à microcirculation saine nous a permis de montrer un impact de la capnie sur les débits microcirculatoires et sur le gradient veino-artériel en CO2 (GvaCO2). On observe en microscopie confocale une diminution des débits microcirculatoires (p < 0,0003), passant de 60 cellules/min à 54 cellules/min pendant l hypocapnie, soit 10%. Dans le même temps, le GvaCO2 varie quant à lui de près de 400 %. Alors qu'il est en moyenne de 2.4 mmHg à l état basal, il est de 14 mmHg en hypocapnie [6 - 20,8 mmHg], (p < 0,0001). Ce travail plaide pour un impact probable de la capnie sur le débit. Ces variations de débit microcirculatoire expliquent probablement en partie les variations GvaCO2 induites par les modifications de la capnie. Cette diminution visualisée en microscopie confocale n est pas contredite par les résultats obtenus avec la NIRS lors de la phase d'hypocapnie. La très large augmentation du GvaCO2 en hypocapnie n'est probablement pas complètement expliquée par cette modeste diminution du débit microcirculatoire. Ces modifications ne sont pas plus expliquées par les effets Bohr et Haldane. Pour tenter de comprendre cette forte augmentation du GvaCO2, en hypocapnie et l effet inverse en hypercapnie, nous évoquons une hypothèse d hibernation cellulaire en hypercapnie. Cet état de repos des cellules pourrait être la conséquence d'une inhibition des processus enzymatiques de la glycolyse acidose nécessaire à la production d'énergie. A l'inverse, l'augmentation de l'activité enzymatique en alcalose respiratoire expliquerait l'augmentation du gradient et des lactates en hypocapnie. Conclusion : En somme, notre étude montre grâce à la microscopie confocale, une diminution du débit microcirculatoire en hypocapnie. Cependant l'augmentation du GvaCO2 semble incomplètement expliquée par les modifications microcirculatoires. Nous proposons une hypothèse métabolique pour tenter d'expliquer les variations de GvaCO2. De ce fait, de nouvelles études sont nécessaires pour confirmer nos résultats et tester cette hypothèse.ST ETIENNE-BU Médecine (422182102) / SudocSudocFranceF

The effect of cardiac output variation on pulsatility index of middle cerebral artery (an exercise model)

LYON1-BU Santé (693882101) / SudocSudocFranceF

Impact d'une augmentation du débit cardiaque sur le débit sanguin cérébral chez le traumatisé crânien grave

LYON1-BU Santé (693882101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Exercise and colorectal cancer: a systematic review and meta-analysis of exercise safety, feasibility and effectiveness

BACKGROUND: This meta-analysis evaluated the safety, feasibility and effect of exercise among individuals with colorectal cancer. METHODS: A database search (CINAHL, Ebscohost, MEDLINE, Pubmed, ProQuest Health and Medical Complete, ProQuest Nursing, Science Direct) for randomised, controlled, exercise trials involving individuals with colorectal cancer, published before January 1, 2020 was undertaken. Safety (adverse events), feasibility (withdrawal and adherence rates) and effect data (health outcomes including quality of life, QoL) were abstracted. Risk difference (RD) and standardised mean differences (SMD) were calculated to compare safety and effects between exercise and usual care (UC). Subgroup analyses were conducted to assess whether outcomes differed by exercise mode, duration, supervision and treatment. Risk of bias was assessed using the Physiotherapy Evidence Database tool. RESULTS: For the 19 trials included, there was no difference in adverse event risk between exercise and UC (RD = 0.00; 95% CI:-0.01, 0.01, p = 0.92). Median withdrawal rate was 12% (0-22%) and adherence was 86% (42-91%). Significant effects of exercise compared to UC were observed for QoL, fatigue, aerobic fitness, upper-body strength, depression, sleep and reduced body fat (SMD = 0.21-0.66, p

Are Females More Resistant to Extreme Neuromuscular Fatigue?

Purpose - Despite interest in the possibility of females outperforming males in ultraendurance sporting events, little is known about the sex differences in fatigue during prolonged locomotor exercise. This study investigated possible sex differences in central and peripheral fatigue in the knee extensors and plantar flexors resulting from a 110-km ultra-trail-running race. Methods - Neuromuscular function of the knee extensors and plantar flexors was evaluated via transcranial magnetic stimulation (TMS) and electrical nerve stimulation before and after an ultra-trail-running race in 20 experienced ultraendurance trail runners (10 females and 10 males matched by percent of the winning time by sex) during maximal and submaximal voluntary contractions and in relaxed muscle. Results - Maximal voluntary knee extensor torque decreased more in males than in females (−38% vs −29%, P = 0.006) although the reduction in plantar flexor torque was similar between sexes (−26% vs −31%). Evoked mechanical plantar flexor responses decreased more in males than in females (−23% vs −8% for potentiated twitch amplitude, P = 0.010), indicating greater plantar flexor peripheral fatigue in males. Maximal voluntary activation assessed by TMS and electrical nerve stimulation decreased similarly in both sexes for both muscle groups. Indices of knee extensor peripheral fatigue and corticospinal excitability and inhibition changes were also similar for both sexes. Conclusions - Females exhibited less peripheral fatigue in the plantar flexors than males did after a 110-km ultra-trail-running race and males demonstrated a greater decrease in maximal force loss in the knee extensors. There were no differences in the magnitude of central fatigue for either muscle group or TMS-induced outcomes. The lower level of fatigue in the knee extensors and peripheral fatigue in the plantar flexors could partly explain the reports of better performance in females in extreme duration running races as race distance increases

Comparison of strategies for monitoring and treating patients at the early phase of severe traumatic brain injury: the multicentre randomised controlled OXY-TC trial study protocol

International audienceIntroduction: Intracranial hypertension is considered as an independent risk factor of mortality and neurological disabilities after severe traumatic brain injury (TBI). However, clinical studies have demonstrated that episodes of brain ischaemia/hypoxia are common despite normalisation of intracranial pressure (ICP). This study assesses the impact on neurological outcome of guiding therapeutic strategies based on the monitoring of both brain tissue oxygenation pressure (PbtO2) and ICP during the first 5 days following severe TBI.Methods and analysis: Multicentre, open-labelled, randomised controlled superiority trial with two parallel groups in 300 patients with severe TBI. Intracerebral monitoring must be in place within the first 16 hours post-trauma. Patients are randomly assigned to the ICP group or to the ICP + PbtO2 group. The ICP group is managed according to the international guidelines to maintain ICP≤20 mm Hg. The ICP + PbtO2 group is managed to maintain PbtO2 ≥20 mm Hg in addition to the conventional optimisation of ICP. The primary outcome measure is the neurological status at 6 months as assessed using the extended Glasgow Outcome Scale. Secondary outcome measures include quality-of-life assessment, mortality rate, therapeutic intensity and incidence of critical events during the first 5 days. Analysis will be performed according to the intention-to-treat principle and full statistical analysis plan developed prior to database freeze.Ethics and dissemination: This study has been approved by the Institutional Review Board of Sud-Est V (14-CHUG-48) and from the National Agency for Medicines and Health Products Safety (Agence Nationale de Sécurité du Médicament et des produits de santé) (141 435B-31). Results will be presented at scientific meetings and published in peer-reviewed publications.The study was registered with ClinTrials NCT02754063 on 28 April 2016 (pre-results)