Mathieu Raux

Extracorporeal life support following out-of-hospital refractory cardiac arrest

IntroductionExtracorporeal life support (ECLS) has recently shown encouraging results in the resuscitation of in-hospital (IH) refractory cardiac arrest. We assessed the use of ECLS following out-of-hospital (OH) refractory cardiac arrest.MethodsWe evaluated 51 consecutive patients who experienced witnessed OH refractory cardiac arrest and received automated chest compression and ECLS upon arrival in the hospital. Patients with preexisting severe hypothermia who experienced IH cardiac arrest were excluded. A femorofemoral ECLS was set up on admission to the hospital by a mobile cardiothoracic surgical team.ResultsFifty-one patients were included (mean age, 42 ± 15 years). The median delays from cardiac arrest to cardiopulmonary resuscitation and ECLS were, respectively, 3 minutes (25th to 75th interquartile range, 1 to 7) and 120 minutes (25th to 75th interquartile range, 102-149). Initial rhythm was ventricular fibrillation in 32 patients (63%), asystole in 15 patients (29%) patients and pulseless rhythm in 4 patients (8%). ECLS failed in 9 patients (18%). Only two patients (4%) (95% confidence interval, 1% to 13%) were alive at day 28 with a favourable neurological outcome. There was a significant correlation (r = 0.36, P = 0.01) between blood lactate and delay between cardiac arrest and onset of ECLS, but not with arterial pH or blood potassium level. Deaths were the consequence of multiorgan failure (n = 43; 47%), brain death (n = 10; 20%) and refractory hemorrhagic shock (n = 7; 14%), and most patients (n = 46; 90%) died within 48 hours.ConclusionsThis poor outcome suggests that the use of ECLS should be more restricted following OH refractory cardiac arrest.

Prognostic Significance of Blood Lactate and Lactate Clearance in Trauma Patients

Background:Lactate has been shown to be a prognostic biomarker in trauma. Although lactate clearance has already been proposed as an intermediate endpoint in randomized trials, its precise role in trauma patients remains to be determined. Methods:Blood lactate levels and lactate clearance (LC) were calculated at admission and 2 and 4 h later in trauma patients. The association of initial blood lactate level and lactate clearance with mortality was tested using receiver-operating characteristics curve, logistic regression using triage scores, Trauma Related Injury Severity Score as a reference standard, and reclassification method. Results:The authors evaluated 586 trauma patients (mean age 38 ± 16 yr, 84% blunt and 16% penetrating, mortality 13%). Blood lactate levels at admission were elevated in 327 (56%) patients. The lactate clearance should be calculated within the first 2 h after admission as LC0–2 h was correlated with LC0–4 h (R2 = 0.55, P < 0.001) but not with LC2–4 h (R2 = 0.04, not significant). The lactate clearance provides additional predictive information to initial blood lactate levels and triage scores and the reference score. This additional information may be summarized using a categorical approach (i.e., less than or equal to −20 %/h) in contrast to initial blood lactate. The results were comparable in patients with high (5 mM/l or more) initial blood lactate. Conclusions:Early (0–2 h) lactate clearance is an important and independent prognostic variable that should probably be incorporated in future decision schemes for the resuscitation of trauma patients.

Electroencephalographic evidence for pre-motor cortex activation during inspiratory loading in humans

Faced with mechanical inspiratory loading, awake animals and anaesthetized humans develop alveolar hypoventilation, whereas awake humans do defend ventilation. This points to a suprapontine compensatory mechanism instead of or in addition to the ‘traditional’ brainstem respiratory regulation. This study assesses the role of the cortical pre‐motor representation of inspiratory muscles in this behaviour. Ten healthy subjects (age 19–34 years, three men) were studied during quiet breathing, CO2‐stimulated breathing, inspiratory resistive loading, inspiratory threshold loading, and during self‐paced voluntary sniffs. Pre‐triggered ensemble averaging of Cz EEG epochs starting 2.5 s before the onset of inspiration was used to look for pre‐motor activity. Pre‐motor potentials were present during voluntary sniffs in all subjects (average latency (±s.d.): 1325 ± 521 ms), but also during inspiratory threshold loading (1427 ± 537 ms) and during inspiratory resistive loading (1109 ± 465 ms). Pre‐motor potentials were systematically followed by motor potentials during inspiratory loading. Pre‐motor potentials were lacking during quiet breathing (except in one case) and during CO2‐stimulated breathing (except in two cases). The same pattern was observed during repeated experiments at an interval of several weeks in a subset of three subjects. The behavioural component of inspiratory loading compensation in awake humans could thus depend on higher cortical motor areas. Demonstrating a similar role of the cerebral cortex in the compensation of disease‐related inspiratory loads (e.g. asthma attacks) would have important pathophysiological implications: it could for example contribute to explain why sleep is both altered and deleterious in such situations.

Postoperative Admission to a Dedicated Geriatric Unit Decreases Mortality in Elderly Patients with Hip Fracture

Background Elderly patients with hip fracture have a 5 to 8 fold increased risk of death during the months following surgery. We tested the hypothesis that early geriatric management of these patients focused on co-morbidities and rehabilitation improved long term mortality. Methods and Findings In a cohort study over a 6 year period, we compared patients aged >70 years with hip fracture admitted to orthopedic versus geriatric departments in a time series analysis corresponding to the creation of a dedicated geriatric unit. Co-morbidities were assessed using the Cumulative Illness Rating Scale (CIRS). Each cohort was compared to matched cohorts extracted from a national registry (n = 51,275) to validate the observed results. Main outcome measure was 6-month mortality. We included 131 patients in the orthopedic cohort and 203 in the geriatric cohort. Co-morbidities were more frequent in the geriatric cohort (median CIRS: 8 vs 5, P<0.001). In the geriatric cohort, the proportion of patients who never walked again decreased (6% versus 22%, P<0.001). At 6 months, re-admission (14% versus 29%, P = 0.007) and mortality (15% versus 24%, P = 0.04) were decreased. When co-morbidities were taken into account, the risk ratio of death at 6 months was reduced (0·43, 95%CI 0·25 to 0·73, P = 0.002). Using matched cohorts, the average treatment effects on the treated associated to early geriatric management indicated a reduction in hospital mortality (−63%; 95% CI: −92% to −6%, P = 0.006). Conclusions Early admission to a dedicated geriatric unit improved 6-month mortality and morbidity in elderly patients with hip fracture.

The concept of damage control: extending the paradigm in the prehospital setting.

OBJECTIVE The purpose of this review is to present the progressive extension of the concept of damage control resuscitation, focusing on the prehospital phase. ARTICLE TYPE Review of the literature in Medline database over the past 10 years. DATA SOURCE Medline database looking for articles published in English or in French between April 2002 and March 2013. Keywords used were: damage control resuscitation, trauma damage control, prehospital trauma, damage control surgery. Original articles were firstly selected. Editorials and reviews were secondly studied. DATA SYNTHESIS The importance of early management of life-threatening injuries and rapid transport to trauma centers has been widely promulgated. Technical progress appears for external methods of hemostasis, with the development of handy tourniquets and hemostatic dressings, making the crucial control of external bleeding more simple, rapid and effective. Hypothermia is independently associated with increased risk of mortality, and appeared accessible to improvement of prehospital care. The impact of excessive fluid resuscitation appears negative. The interest of hypertonic saline is denied. The place of vasopressor such as norepinephrine in the early resuscitation is still under debate. The early use of tranexamic acid is promoted. Specific transfusion strategies are developed in the prehospital setting. CONCLUSION It is critical that both civilian and military practitioners involved in trauma continue to share experiences and constructive feedback. And it is mandatory now to perform well-designed prospective clinical trials in order to advance the topic.

Unrecognized suffering in the ICU: addressing dyspnea in mechanically ventilated patients.

BackgroundIntensive care unit (ICU) patients are exposed to many sources of discomfort. Although increasing attention is being given to the detection and treatment of pain, very little is given to the detection and treatment of dyspnea (defined as “breathing discomfort”).MethodsPublished information on the prevalence, mechanisms, and potential negative impacts of dyspnea in mechanically ventilated patients are reviewed. The most appropriate tools to detect and quantify dyspnea in ICU patients are also assessed. Results/ConclusionsGrowing evidence suggests that dyspnea is a frequent issue in mechanically ventilated ICU patients, is highly associated with anxiety and pain, and is improved in many patients by altering the ventilator settings.ConclusionsFuture studies are needed to better delineate the impact of dyspnea in the ICU and to define diagnostic, monitoring and therapeutic protocols.

Neurally adjusted ventilatory assist improves patient–ventilator interaction during postextubation prophylactic noninvasive ventilation*

Objectives:To compare the respective impact of pressure support ventilation and naturally adjusted ventilatory assist, with and without a noninvasive mechanical ventilation algorithm, on patient–ventilator interaction. Design:Prospective 2-month study. Setting:Adult critical care unit in a tertiary university hospital. Patients:Seventeen patients receiving a prophylactic postextubation noninvasive mechanical ventilation. Interventions:Patients were randomly mechanically ventilated for 10 mins with: pressure support ventilation without a noninvasive mechanical ventilation algorithm (PSV-NIV–), pressure support ventilation with a noninvasive mechanical ventilation algorithm (PSV-NIV+), neurally adjusted ventilatory assist without a noninvasive mechanical ventilation algorithm (NAVA-NIV–), and neurally adjusted ventilatory assist with a noninvasive mechanical ventilation algorithm (NAVA-NIV+). Measurements and Main Results:Breathing pattern descriptors, diaphragm electrical activity, leak volume, inspiratory trigger delay, inspiratory time in excess, and the five main asynchronies were quantified. Asynchrony index and asynchrony index influenced by leaks were computed. Peak inspiratory pressure and diaphragm electrical activity were similar for each of the four experimental conditions. For both pressure support ventilation and neurally adjusted ventilatory assist, the noninvasive mechanical ventilation algorithm significantly reduced the level of leakage (p < .01). Inspiratory trigger delay was not affected by the noninvasive mechanical ventilation algorithm but was shorter in neurally adjusted ventilatory assist than in pressure support ventilation (p < .01). Inspiratory time in excess was shorter in neurally adjusted ventilatory assist and PSV-NIV+ than in PSV-NIV– (p < .05). Asynchrony index was not affected by the noninvasive mechanical ventilation algorithm but was significantly lower in neurally adjusted ventilatory assist than in pressure support ventilation (p < .05). Asynchrony index influenced by leaks was insignificant with neurally adjusted ventilatory assist and significantly lower than in pressure support ventilation (p < .05). There was more double triggering with neurally adjusted ventilatory assist. Conclusions:Both neurally adjusted ventilatory assist and a noninvasive mechanical ventilation algorithm improve patient–ventilator synchrony in different manners. NAVA-NIV+ offers the best compromise between a good patient–ventilator synchrony and a low level of leaks. Clinical studies are required to assess the potential clinical benefit of neurally adjusted ventilatory assist in patients receiving noninvasive mechanical ventilation. Trial Registration:Clinicaltrials.gov Identifier NCT01280760.

Scalene muscle activity during progressive inspiratory loading under pressure support ventilation in normal humans

We hypothesized that (1) in healthy humans subjected to intermittent positive pressure non-invasive ventilation, changes in the ventilator trigger sensitivity would be associated with increased scalene activity, (2) if properly processed - through inspiratory phase-locked averaging - surface electromyograms (EMG) of the scalenes would reliably detect and quantify this, (3) there would be a correlation between dyspnea and scalene EMG. Surface and intramuscular EMG activity of scalene muscles were measured in 10 subjects. They breathed quietly through a face mask for 10min and then were connected to a mechanical ventilator. Recordings were performed during three 15-min epochs where the subjects breathed against an increasingly negative pressure trigger (-5%, -10% and -15% of maximal inspiratory pressure). With increasing values of the inspiratory trigger, inspiratory efforts, dyspnea and the scalene activity increased significantly. The scalene EMG activity level was correlated with the esophageal pressure time product and with dyspnea intensity. Inspiration-adjusted surface EMG averaging could be useful to detect small increases of the scalene muscles activity during mechanical ventilation.

Perioperative management of elderly patients with hip fracture.

1336 December 2014 W ORLDWIDE 1.6 million patients suffer from hip fracture every year, and this number has increased by 25% every decade as the population continues to grow.1 Nevertheless, a decrease in hip fracture rate has been recently observed, particularly in women (up to −24% in women older than 85 yr), owing to several factors including awareness about osteoporosis and the danger of falls.2 Hip fracture has devastating consequences in the elderly patients and thus is associated with a poor outcome. This contrasts markedly with the relatively simple surgical procedures needed for treatment. One third of elderly patients with hip fracture are dead 1 yr later and, in surviving patients, hip fractures have a negative effect on daily life activities and quality of life.1–3 The elderly patients with hip fracture remain a medical challenge for the anesthesiologist, mainly because of the frequent and numerous comorbidities encountered; moreover, the incidence of these comorbidities has increased during the past years.2 Many improvements have been introduced in the care of these patients, including improved surgical devices, earlier mobilization, prophylactic administration of antibiotics and anticoagulant, as well as increased rate of admission into rehabilitation unit. Nevertheless, the mortality rate has plateaued since 1998.2 Given the magnitude of the problem, some effective strategies have been recently proposed to prevent mortality after hip fracture.3,4 This Clinical Concept and Commentary summarizes these strategies and explain the future directions for research, but focuses on specific issues related to hip fracture and not to more general aspect related to anesthesia in elderly patients.5 Morbidity and Mortality After hip fracture, in-hospital mortality ranges from 2.3 to 13.9%, but the risk persists beyond the immediate surgical period with 6-month mortality rates ranging from 12 to 23%.3 The mortality risk increases within 6 months and thereafter decreases, and is higher in men. When compared to elective hip replacements, patients presenting with hip fracture have a 6to 15-fold mortality risk.6 This difference is explained by the high prevalence of preexisting medical conditions in this population: 75% of patients are older than 70 yr,1 and 95% of patients present with at least one major preoperative comorbidity (fig. 1).7 Three in four hip fracture-associated deaths may be causally related to preexisting medical conditions rather than the fracture itself.8 This indicates that the hip fracture destabilizes a frail elderly population with a high burden of preexisting morbidities, thereby resulting in excess mortality. Some new acute conditions (stroke and cardiac events) may have also provoked falling and thus hip fracture. Frailty should be understood as a vulnerability and a decline of physiologic age-related functional capacities to confront an acute stress such as hip fracture. To summarize, it can be considered in the presence of at least one of the following conditions: (1) advanced age, the “oldest old” (i.e., >90 yr); (2) presence of several comorbidities; and (3) new acute medical conditions. Any of these conditions can weaken elderly patients with hip fracture.

Cerebral cortex activation during experimentally induced ventilator fighting in normal humans receiving noninvasive mechanical ventilation.

Background:Mechanical ventilation is delivered to sedated patients during anesthesia, but also to nonsedated patients (ventilator weaning, noninvasive ventilation). In these circumstances, patient–ventilator asynchrony may occur, provoking discomfort and unduly increasing work of breathing. In certain cases, it is associated with an increased inspiratory load. Inspiratory loading in awake humans activates the premotor cortical regions, as illustrated by the occurrence of electroencephalographic premotor potentials. In normal humans during noninvasive ventilation, the authors used an experimental model of patient–ventilator asynchrony to determine whether premotor cortical activation occurs in this setting. Methods:Noninvasive pressure support ventilation was administered to seven healthy volunteers aged 22–27 yr with continuous electroencephalographic recordings in Cz. The ventilator settings were first adjusted to make the subjects feel comfortable (“comfort”), and then modified to induce respiratory “discomfort” (evaluated on a 10-cm visual analog scale). This was achieved by setting the ventilator to a higher trigger level, reducing the slope of the pressure support rise, and reducing the level of pressure support. The settings were finally brought back to their initial values. To identify a respiratory-related premotor activity, a minimum of 80 preinspiratory electroencephalographic epochs were averaged. Results:Altering ventilator settings induced respiratory discomfort (average visual scale 4 [1.5–6.0] vs. 0 [0–1.0] cm during “comfort”; P < 0.0001). This was associated with premotor potentials in all cases, which disappeared upon return to “comfort.” Conclusions:This study indicates that “ventilator fighting” in healthy humans is associated with an activation of higher cerebral areas. Premotor potentials could thus be markers of patient–ventilator asynchrony at the brain level. Both corroboration in patients and the elucidation of the causative or reactive nature of the association are needed before determining clinical implications.