Guillaume Louart

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.

An Increase in Aortic Blood Flow after an Infusion of 100 ml Colloid over 1 Minute Can Predict Fluid Responsiveness The Mini-fluid Challenge Study

Background: Predicting fluid responsiveness remains a difficult question in hemodynamically unstable patients. The authors objective was to test whether noninvasive assessment by transthoracic echocardiography of subaortic velocity time index (VTI) variation after a low volume of fluid infusion (100 ml hydroxyethyl starch) can predict fluid responsiveness. Methods: Thirty-nine critically ill ventilated and sedated patients with acute circulatory failure were prospectively studied. Subaortic VTI was measured by transthoracic echocardiography before fluid infusion (baseline), after 100 ml hydroxyethyl starch infusion over 1 min, and after an additional infusion of 400 ml hydroxyethyl starch over 14 min. The authors measured the variation of VTI after 100 ml fluid (&Dgr;VTI100) for each patient. Receiver operating characteristic curves were generated for (&Dgr;VTI100). When available, receiver operating characteristic curves also were generated for pulse pressure variation and central venous pressure. Results: After 500 ml volume expansion, VTI increased ≥ 15% in 21 patients (54%) defined as responders. &Dgr;VTI100 ≥ 10% predicted fluid responsiveness with a sensitivity and specificity of 95% and 78%, respectively. The area under the receiver operating characteristic curves of &Dgr;VTI100 was 0.92 (95% CI: 0.78–0.98). In 29 patients, pulse pressure variation and central venous pressure also were available. In this subgroup of patients, the area under the receiver operating characteristic curves for &Dgr;VTI100, pulse pressure variation, and central venous pressure were 0.90 (95% CI: 0.74–0.98, P < 0.05), 0.55 (95% CI: 0.35–0.73, NS), and 0.61 (95% CI: 0.41–0.79, NS), respectively. Conclusion: In patients with low volume mechanical ventilation and acute circulatory failure, &Dgr;VTI100 accurately predicts fluid responsiveness.

The intrathoracic blood volume index as an indicator of fluid responsiveness in critically ill patients with acute circulatory failure: a comparison with central venous pressure.

BACKGROUND: The intrathoracic blood volume index (ITBVI) and central venous pressure (CVP) are routinely used to predict fluid responsiveness in critically ill patients with acute circulatory failure (systolic blood pressure <90 mm Hg or vasopressor requirement). However, they have never been compared. METHODS: In this prospective interventional study, we included 35 (21 men) mechanically ventilated and sedated patients with acute cardiovascular failure requiring cardiac output measurement (transpulmonary thermodilution technique). Fluid responsiveness was defined as an increase in stroke index (cardiac output/heart rate/body surface area) ≥15%. Receiver operating characteristic curves were generated for ITBVI and CVP. RESULTS: Fluid challenge induced a stroke index increase ≥15% in 18 (51%) patients (responders). At baseline, no studied hemodynamic variables were different between responders and nonresponders. The areas under the receiver operating characteristic curves were 0.64 [95% CI: 0.46–0.80] for ITBVI and 0.68 [95% CI: 0.50–0.83] for CVP, without any statistical difference (P = 0.73). The best cut-off values for CVP and ITBVI were 9 mm Hg (sensitivity = 61%; specificity = 82%) and 928 mL · m−2 (sensitivity = 78%; specificity = 53%). CONCLUSION: ITBVI is similar to CVP in its ability to predict fluid responsiveness in critically ill patients with acute circulatory failure.

Reversal of bupivacaine-induced cardiac electrophysiologic changes by two lipid emulsions in anesthetized and mechanically ventilated piglets.

BACKGROUND: Accidental IV administration of bupivacaine can compromise cardiovascular function by inducing lethal arrhythmias whose hemodynamic consequences may be alleviated by lipid emulsions. However, little is known about the electrophysiologic effects of lipid emulsions. In this study, we assessed whether 2 different lipid emulsions can reverse cardiac electrophysiologic impairment induced by the IV administration of bupivacaine in anesthetized and mechanically ventilated piglets. METHODS: Bupivacaine (4 mg · kg−1) was injected over a 30-second period in 26 piglets. Thirty seconds after the end of bupivacaine injection, 1.5 mL · kg−1 saline solution for the control group, and long-chain triglyceride emulsion (LCT group) or a mixture of long-chain and medium-chain triglyceride emulsion (LCT/MCT group) were infused over 1 minute. Cardiac conduction variables and hemodynamic variables were monitored for 30 minutes after injection. RESULTS: Bupivacaine induced similar electrophysiologic and hemodynamic changes. After 3 minutes, His ventricle intervals (median and interquartiles) were 100 (85–105), 45 (35–55), and 53 (48–73) milliseconds in the control, LCT, and LCT/MCT groups, respectively (P < 0.001 between control and both lipid emulsion groups). Lipid emulsions also reversed the effects on QRS duration, atrial-His, and PQ (the onset of the P wave to the Q wave of the QRS complex) intervals. LCT/MCT emulsion restored the decrease in maximal first derivative of left ventricular pressure (P < 0.01 after 3 minutes versus control group). CONCLUSIONS: LCT and LCT/MCT emulsions reversed the lengthening of His ventricle, QRS, atrial-His, and PQ intervals induced by the IV injection of 4 mg · kg−1 bupivacaine.

Does the type of fluid affect rapidity of shock reversal in an anaesthetized-piglet model of near-fatal controlled haemorrhage? A randomized study

BACKGROUND The optimal resuscitation fluid for the early treatment of severe bleeding patients remains highly debated. The objective of this experimental study was to compare the rapidity of shock reversal with lactated Ringer (LR) or hydroxyethyl starch (HES) 130/0.4 at the early phase of controlled haemorrhagic shock. To assess the influence of vascular permeability in this model, we measured plasma vascular endothelial growth factor (VEGF) levels during the experiment. METHODS Thirty-six anaesthetized and mechanically ventilated piglets were bled (<30 ml kg(-1)) to hold mean arterial pressure (MAP) at 40 mm Hg for more than 30 min and were resuscitated in two randomized groups: LR (n=14) or HES (n=14) at 1 ml kg(-1) min(-1) until MAP reached its baseline value of ±10%. MAP was maintained at its baseline value for 1 h. The time and fluid volume necessary to restore the baseline MAP value were measured. RESULTS The time to restore the baseline MAP value of ±10% was significantly lower in the HES group (P<0.001). During the initial resuscitation phase, the infused volume was 279 (119) ml in the HES group and 1011 (561) ml in the LR group (P<0.0001). During the stabilization phase, the infused volume was 119 (124) ml in the HES group and 541 (506) ml in the LR group. Biological data and plasma VEGF levels were similar between the groups. CONCLUSIONS Restoration of MAP was four times faster with HES than with LR in the early phase of controlled haemorrhagic shock. However, there was no evidence of increased vascular permeability.

Could B-type Natriuretic Peptide (BNP) plasma concentration be useful to predict fluid in critically ill patients with acute circulatory failure?

BACKGROUND AND OBJECTIVES As B-type Natriuretic Peptide (BNP) is a marker of ventricular wall stress, the present study was aimed at determining whether plasma BNP concentration could predict fluid responsiveness in critically ill patients with acute circulatory failure. METHODS This prospective and non randomized interventional study included 33 sedated, mechanically ventilated patients, with acute circulatory failure requiring cardiac output measurement and fluid challenge. Plasma BNP concentration was measured before and after fluid challenge (250 to 500 ml with infusion rate=999 ml/h). An increase in stroke index (SI) greater than or equal to 15% allowed separation of responders from nonresponders. Receiver operating characteristic (ROC) curves were generated for BNP and compared to that of central venous pressure (CVP) that is routinely considered as a marker of cardiac preload. RESULTS Among 33 patients, there were 24 responders. At baseline, BNP plasma values were less in responders (328 [35-1190] pg/ml versus 535 [223-5000] pg/ml, p<0.03). The area under the ROC curves was 0.74+/-0.11, that was similar to the area under the ROC curve for CVP (0.77+/-0.10). The best cut-off value of plasma BNP level for predicting fluid responsiveness was 193 pg/ml (sensitivity: 38%, specificity: 100%, positive predictive value: 100%, negative predictive value: 38%, accuracy: 55%). Fluid challenge did not increase plasma BNP concentrations in responders and nonresponders. CONCLUSION In critically ill patients with acute circulatory failure, BNP does not accurately predict fluid responsiveness.

Acidose lactique sur intoxication volontaire à l'acide valproïque

98 %, tandis que la pression artérielle et la fréquence cardiaque variaient de moins de 10 % par rapport aux valeurs mesurées avant l’induction. La fréquence respiratoire restait autour de 10 c/min. Au cours des 45 minutes de procédure, 280 mg de propofol ont été administrés. Lors du réveil, le patient restait peu réactif, justifiant l’analyse des gaz du sang artériel (Tableau 1). Le patient était alors intubé et ventilé mécaniquement pendant deux heures, la radiographie thoracique ne retrouvait ni pneumothorax ni atélectasie. Le retour à domicile était possible deux jours après la colonoscopie, sans séquelle. Le transfert de compétence aux non-anesthésistes a été [1] et continue d’être discuté [2]. Le transfert de charges vers des infirmiers formés est évoqué dans le « Rapport Berland » (http://www.sante. gouv.fr/htm/actu/berland/rapport_complet.pdf) à l’image d’expériences américaine et britannique. Il repose sur le caractère rapidement réversible du propofol, le monitorage de la SpO2 et l’apport systématique d’oxygène. Notre observation montre que ces trois éléments n’éliminent pas tout risque respiratoire. La diminution de la réponse aiguë à l’hypoxie est connue, y compris après de faibles doses de propofol [3]. Les désaturations en oxygène observées en pratique sont habituellement réversibles après stimulation et administration d’oxygène nasal. Cependant, une série de plus de 9000 patients a retrouvé 40 cas de nécessité de ventilation assistée, neuf intubations endotrachéales et 28 surveillances prolongées après la procédure. Quatre patients sont décédés, la sédation ayant été en cause dans trois cas [4].

Assessment of neutrophil gelatinase-associated lipocalin in the brain-dead organ donor to predict immediate graft function in kidney recipients: a prospective, multicenter study.

Background:Delayed graft function is a major determinant of long-term renal allograft survival. Despite considerable efforts to improve donor selection and matching, incidence of delayed graft function remains close to 25%. As neutrophil gelatinase-associated lipocalin (NGAL) has been shown to predict acute renal failure, the authors tested the hypothesis that NGAL measurement in brain-dead donors predicts delayed graft function in kidney recipients. Methods:In a prospective, multicenter, observational study, serum NGAL was measured in donors at the time of transfer to operating room. The primary endpoint was the delayed graft function, defined as the need for renal replacement therapy during the first week posttransplantation. Results:Among 159 included brain-dead donors, 146 were analyzable leading to 243 renal transplantations. Of these, 56 (23%) needed renal replacement therapy. Donors’ NGAL values were similar in case of both delayed and normal graft function in recipients. The area under the receiver-operating curve for NGAL to predict the need for renal replacement therapy before day 8 was 0.50 (95% CI, 0.42 to 0.59). The area under curve for NGAL to predict failure to return to a normal graft function at day 8 was 0.51 (95% CI, 0.44 to 0.59). Using multivariate analysis, NGAL was not associated to the need for renal replacement therapy (odds ratio, 0.99; 95% CI, 0.98 to1.00) or failure to return to a normal graft function at day 8 (odds ratio, 1.00; 95% CI, 0.99 to 1.00). Conclusion:NGAL measurement in brain-dead donors at the time of recovery failed to predict delayed or normal graft function in kidney recipients.

Does the infusion rate of fluid affect rapidity of mean arterial pressure restoration during controlled hemorrhage

OBJECTIVE This study aimed to compare 2 fluid infusion rates of lactated Ringer (LR) and hydroxyethyl starch (HES) 130/0.4 on hemodynamic restoration at the early phase of controlled hemorrhagic shock. METHODS Fifty-six anesthetized and ventilated piglets were bled until mean arterial pressure (MAP) reached 40 mm Hg. Controlled hemorrhage was maintained for 30 minutes. After this period, 4 resuscitation groups were studied (n=14 for each group): HES infused at 1 or 4mL/kg per minute or LR1 infused at 1 or 4mL/kg per minute until baseline MAP was restored. Hemodynamic assessment using PiCCO monitoring and biological data were collected. RESULTS Time to restore baseline MAP ±10% was significantly lower in LR4 group (11±11 minutes) compared to LR1 group (41±25 minutes) (P=.0004). Time to restore baseline MAP ±10% was significantly lower in HES4 group (4±3 minutes) compared to HES1 (11±4 minutes) (P=.0003). Time to restore baseline MAP ±10% was significantly lower with HES vs LR whatever the infusion rate. No statistically significant difference was observed in cardiac output, central venous saturation, extravascular lung water, and arterial lactate between 4 and 1 mL/kg per minute groups. CONCLUSIONS In this controlled hemorrhagic shock model, a faster infusion rate (4 vs 1mL/kg per minute) significantly decreased the time for restoring baseline MAP, regardless of the type of infused fluid. The time for MAP restoration was significantly shorter for HES as compared to LR whatever the fluid infusion rate.

Élargissement des plages horaires de visites dans une unité de réanimation : l’avis des proches

OBJECTIVE The present study was aimed at assessing the opinion of the patients relatives concerning the visiting hours in the ICU. METHOD The visiting relatives were questioned about the information delivered in the Unit (assessed as 0 for minimal and 10 for maximal assessments, respectively) and the hypothesis to extend the Units visiting hours. The responses were given independently by the relatives. RESULTS Eighty-seven out of 64 relatives responded (63% females). The delivered information was assessed by a median note=10 (interquartile: [8-10]). The current visiting times (2h per day during the week, 6h in weekend) were assessed as sufficient by 48 closest (58%). Fifty-four (67%, CI95%=[56-77]) requested more liberal visiting times and 38 (46%, CI95%=[36-57]) requested 24h visiting policy. Five relatives (6%, CI95%=[1-11]) would like to be present during patients care. Most relatives do not wish to assist to patients care to avoid interfering with caregivers workload (81%), to respect the patients intimacy (49%) and by fear of being impressed by the care (23%). Forty percent of the relatives would like to help feeding the patient. CONCLUSION Most of the relatives wish for more liberal visiting times without interfering with patients care.