Hervé Quintard

Respiratory variations of inferior vena cava diameter to predict fluid responsiveness in spontaneously breathing patients with acute circulatory failure: need for a cautious use

IntroductionTo investigate whether respiratory variation of inferior vena cava diameter (cIVC) predict fluid responsiveness in spontaneously breathing patients with acute circulatory failure (ACF).MethodsForty patients with ACF and spontaneous breathing were included. Response to fluid challenge was defined as a 15% increase of subaortic velocity time index (VTI) measured by transthoracic echocardiography. Inferior vena cava diameters were recorded by a subcostal view using M Mode. The cIVC was calculated as follows: (Dmax - Dmin/Dmax) × 100 and then receiver operating characteristic (ROC) curves were generated for cIVC, baseline VTI, E wave velocity, E/A and E/Ea ratios.ResultsAmong 40 included patients, 20 (50%) were responders (R). The causes of ACF were sepsis (n = 24), haemorrhage (n = 11), and dehydration (n = 5). The area under the ROC curve for cIVC was 0.77 (95% CI: 0.60-0.88). The best cutoff value was 40% (Se = 70%, Sp = 80%). The AUC of the ROC curves for baseline E wave velocity, VTI, E/A ratio, E/Ea ratio were 0.83 (95% CI: 0.68-0.93), 0.78 (95% CI: 0.61-0.88), 0.76 (95% CI: 0.59-0.89), 0.58 (95% CI: 0.41-0.75), respectively. The differences between AUC the ROC curves for cIVC and baseline E wave velocity, baseline VTI, baseline E/A ratio, and baseline E/Ea ratio were not statistically different (p = 0.46, p = 0.99, p = 1.00, p = 0.26, respectively).ConclusionIn spontaneously breathing patients with ACF, high cIVC values (>40%) are usually associated with fluid responsiveness while low values (< 40%) do not exclude fluid responsiveness.

Improvement of Neuroenergetics by Hypertonic Lactate Therapy in Patients with Traumatic Brain Injury Is Dependent on Baseline Cerebral Lactate/Pyruvate Ratio

Abstract Energy dysfunction is associated with worse prognosis after traumatic brain injury (TBI). Recent data suggest that hypertonic sodium lactate infusion (HL) improves energy metabolism after TBI. Here, we specifically examined whether the efficacy of HL (3h infusion, 30–40 μmol/kg/min) in improving brain energetics (using cerebral microdialysis [CMD] glucose as a main therapeutic end-point) was dependent on baseline cerebral metabolic state (assessed by CMD lactate/pyruvate ratio [LPR]) and cerebral blood flow (CBF, measured with perfusion computed tomography [PCT]). Using a prospective cohort of 24 severe TBI patients, we found CMD glucose increase during HL was significant only in the subgroup of patients with elevated CMD LPR >25 (n = 13; +0.13 [95% confidence interval (CI) 0.08–0.19] mmol/L, p < 0.001; vs. +0.04 [–0.05–0.13] in those with normal LPR, p = 0.33, mixed-effects model). In contrast, CMD glucose increase was independent from baseline CBF (coefficient +0.13 [0.04–0.21] mmol/L when global CBF was <32.5 mL/100 g/min vs. +0.09 [0.04–0.14] mmol/L at normal CBF, both p < 0.005) and systemic glucose. Our data suggest that improvement of brain energetics upon HL seems predominantly dependent on baseline cerebral metabolic state and support the concept that CMD LPR – rather than CBF – could be used as a diagnostic indication for systemic lactate supplementation following TBI.

Influence of Diaphragmatic Motion on Inferior Vena Cava Diameter Respiratory Variations in Healthy Volunteers

Background:The collapsibility index of inferior vena cava (cIVC) is widely used to decide fluid infusion in spontaneously breathing intensive care unit patients. The authors hypothesized that high inspiratory efforts may induce false-positive high cIVC values. This study aims at determining a value of diaphragmatic motion recorded by echography that could predict a high cIVC (more than or equal to 40%) in healthy volunteers. Methods:The cIVC and diaphragmatic motions were recorded for three levels of inspiratory efforts. Right and left diaphragmatic motions were defined as the maximal diaphragmatic excursions. Receiver operating characteristic curves evaluated the performance of right diaphragmatic motion to predict a cIVC more than or equal to 40% defining the best cutoff value. Results:Among 52 included volunteers, interobserver reproducibility showed a generalized concordance correlation coefficient (&rgr;c) above 0.9 for all echographic parameters. Right diaphragmatic motion correlated with cIVC (r = 0.64, P < 0.0001). Univariate analyses did not show association between cIVC and age, sex, weight, height, or body mass index. The area under the receiver operating characteristic curves for cIVC more than or equal to 40% was 0.87 (95% CI, 0.81 to 0.93). The best diaphragmatic motion cutoff was 28 mm (Youden Index, 0.65) with sensitivity of 89% and specificity of 77%. The gray zone area was 25 to 43 mm. Conclusions:Inferior vena cava collapsibility is affected by diaphragmatic motion. During low inspiratory effort, diaphragmatic motion was less than 25 mm and predicted a cIVC less than 40%. During maximal inspiratory effort, diaphragmatic motion was more than 43 mm and predicted a cIVC more than 40%. When diaphragmatic motion ranged from 25 to 43 mm, no conclusion on cIVC value could be done.

Effect of N-acetylcysteine pretreatment of deceased organ donors on renal allograft function: a randomized controlled trial.

Background Antioxidant donor pretreatment is one of the pharmacologic strategy proposed to prevent renal ischemia-reperfusion injuries and delayed graft function (DGF). The aim of the study was to investigate whether a donor pretreatment with N-acetylcysteine (NAC) reduces the incidence of DGF in adult human kidney transplant recipients. Methods In this randomized, open-label, monocenter trial, 160 deceased heart-beating donors were allowed to perform 236 renal transplantations from September 2005 to December 2010. Donors were randomized to receive, in a single-blind controlled fashion, 600 mg of intravenous NAC 1 hr before and 2 hr after cerebral angiography performed to confirm brain death. Primary endpoint was DGF defined by the need for at least one dialysis session within the first week or a serum creatinine level greater than 200 &mgr;mol/L at day 7 after kidney transplantation. Results The incidence of DGF was similar between donors pretreated with or without NAC (39/118; 33% vs. 30/118; 25.4%; P = 0.19). Requirement for at least one dialysis session was not different between the NAC and No NAC groups (17/118; 14.4% vs. 14/118; 11.8%, P = 0.56). The two groups had comparable serum creatinine levels, estimated glomerular filtration rates, and daily urine output at days 1, 7, 15, and 30 after kidney transplantation as well as at hospital discharge. No difference in recipient mortality nor in 1-year kidney graft survival was observed. Conclusion Donor pretreatment with NAC does not improve delayed graft function after kidney transplantation.

The pharmacokinetic profile of voriconazole during continuous high-volume venovenous hemofiltration in a critically ill patient.

In critically ill patients, dosage adjustment of voriconazole could be helpful when high-volume continuous venovenous hemofiltration is needed. Voriconazole pharmacokinetics were studied in an anuric critically ill patient, under high-volume continuous venovenous hemofiltration, over an interval period after a 4-mg/kg dose of voriconazole. Arterial and effluent voriconazole concentrations were measured after liquid phase extraction using a high-pressure liquid chromatography. The extrapolate area under the curve0-12h of voriconazole was 65 mg/h/L. The total body clearance of voriconazole was 5.4 L/h with a half-life of 16.5 hours and a distribution volume of 128.6 L. The estimated sieving coefficient was 0.58 and the filtration clearance 1.39 L/h. High-volume continuous venovenous hemofiltration could affect voriconazole disposition in contrast with other techniques. Besides, we observed voriconazole accumulation consequence of the saturation of the metabolic clearance resulting from multiple organ failure. Dosage adjustment seems to be required in these conditions, but this observation must be confirmed by a clinical study.

Neuroenergetic Response to Prolonged Cerebral Glucose Depletion after Severe Brain Injury and the Role of Lactate

Lactate may represent a supplemental fuel for the brain. We examined cerebral lactate metabolism during prolonged brain glucose depletion (GD) in acute brain injury (ABI) patients monitored with cerebral microdialysis (CMD). Sixty episodes of GD (defined as spontaneous decreases of CMD glucose from normal to low [<1.0 mmol/L] for at least 2 h) were identified among 26 patients. During GD, we found a significant increase of CMD lactate (from 4 ± 2.3 to 5.4 ± 2.9 mmol/L), pyruvate (126.9 ± 65.1 to 172.3 ± 74.1 μmol/L), and lactate/pyruvate ratio (LPR; 27 ± 6 to 35 ± 9; all, p < 0.005), while brain oxygen and blood lactate remained normal. Dynamics of lactate and glucose supply during GD were further studied by analyzing the relationships between blood and CMD samples. There was a strong correlation between blood and brain lactate when LPR was normal (r = 0.56; p < 0.0001), while an inverse correlation (r = -0.11; p = 0.04) was observed at elevated LPR >25. The correlation between blood and brain glucose also decreased from r = 0.62 to r = 0.45. These findings in ABI patients suggest increased cerebral lactate delivery in the absence of brain hypoxia when glucose availability is limited and support the concept that lactate acts as alternative fuel.

Influence of acute preload changes on mitral annulus velocity measured by tissue Doppler echocardiography in critically ill patients

The assessment of diastolic function remains difficult in critical care patients because of unstable preload conditions. Described as fairly insensitive to preload changes, tissue Doppler velocity measurement at the lateral mitral annulus (e′ lat) may help evaluate diastolic function. Our aim was to prospectively evaluate e′ lat changes in relation to fluid expansion in critically ill patients.

Adult neurogenesis and brain remodelling after brain injury: From bench to bedside?

OBJECTIVE Brain trauma and stroke cause important disabilities. The mechanisms involved are now well described, but all therapeutics developed thus far for neuro-protection are currently unsuccessful at improving neurologic prognosis. The recently studied neuro-restorative time following brain injury may point towards a promising therapeutic approach. The purpose of this paper is to explain the mechanisms of this revolutionary concept, give an overview of related knowledge and discuss its transfer into clinical practice. DATA SOURCES AND SYNTHESIS An overview of the neurogenesis concept using MEDLINE, EMBASE and CENTRAL databases was carried out in May 2014. The clinicaltrials.gov registry was used to search for ongoing clinical trials in this domain. CONCLUSION The concept of brain remodelling upset fundamental ideas concerning the neurologic system and opened new fields of research. Therapies currently under evaluation hold promising results and could have a real prognostic impact in future years, but the translation of these therapies from the laboratory to the clinic is still far from completion.

ICU specialists facing terrorist attack: the Nice experience

Introduction On the night of 14 July 2016, the city of Nice suffered a terrorist attack. A truck drove through a crowd causing initially 84 deaths and 372 injured victims. Most of them suffered multiple crush trauma resulting in brain, thoraco-abdominal and lower limbs injuries. These initial casualties were transferred as follows: 183 to the Nice university level 1 trauma center, 102 to other public and private hospitals in Nice, and 87 to regional public and private hospitals. Among them, 98 were hospitalized in these facilities, most in the Nice trauma center. Of these 98 patients, 18 had surgery during the first night and 11 the following day. During the first hours, 20 victims considered as absolute emergencies were admitted to our ICU.

Fluid therapy in neurointensive care patients: ESICM consensus and clinical practice recommendations

ObjectiveTo report the ESICM consensus and clinical practice recommendations on fluid therapy in neurointensive care patients.DesignA consensus committee comprising 22 international experts met in October 2016 during ESICM LIVES2016. Teleconferences and electronic-based discussions between the members of the committee subsequently served to discuss and develop the consensus process.MethodsPopulation, intervention, comparison, and outcomes (PICO) questions were reviewed and updated as needed, and evidence profiles generated. The consensus focused on three main topics: (1) general fluid resuscitation and maintenance in neurointensive care patients, (2) hyperosmolar fluids for intracranial pressure control, (3) fluid management in delayed cerebral ischemia after subarachnoid haemorrhage. After an extensive literature search, the principles of the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system were applied to assess the quality of evidence (from high to very low), to formulate treatment recommendations as strong or weak, and to issue best practice statements when applicable. A modified Delphi process based on the integration of evidence provided by the literature and expert opinions—using a sequential approach to avoid biases and misinterpretations—was used to generate the final consensus statement.ResultsThe final consensus comprises a total of 32 statements, including 13 strong recommendations and 17 weak recommendations. No recommendations were provided for two statements.ConclusionsWe present a consensus statement and clinical practice recommendations on fluid therapy for neurointensive care patients.