Showing papers by "Benoit Vallet published in 2012"

Can Changes in Arterial Pressure be Used to Detect Changes in Cardiac Output during Volume Expansion in the Perioperative Period

Abstract: BACKGROUND Cardiac output (CO) is rarely monitored during surgery, and arterial pressure remains the only hemodynamic parameter for assessing the effects of volume expansion (VE). However, whether VE-induced changes in arterial pressure accurately reflect changes in CO has not been demonstrated. The authors studied the ability of VE-induced changes in arterial pressure and in pulse pressure variation to detect changes in CO induced by VE in the perioperative period. METHODS The authors studied 402 patients in four centers. Hemodynamic variables were recorded before and after VE. Response to VE was defined as more than 15% increase in CO. The ability of VE-induced changes in arterial pressure to detect changes in CO was assessed using a gray zone approach. RESULTS VE increased CO of more than 15% in 205 patients (51%). Areas under the receiver operating characteristic curves for VE-induced changes in systolic, diastolic, means, and pulse pressure ranged between 0.64 and 0.70, and sensitivity and specificity ranged between 52 and 79%. For these four arterial pressure-derived parameters, large gray zones were found, and more than 60% of the patients lay within this inconclusive zone. A VE-induced decrease in pulse pressure variation of 3% or more allowed detecting a fluid-induced increase in CO of more than 15% with a sensitivity of 90% and a specificity of 77% and a gray zone between 2.2 and 4.7% decrease in pulse pressure variation including 14% of the patients. CONCLUSION Only changes in pulse pressure variation accurately detect VE-induced changes in CO and have a potential clinical applicability.

Assessing the Diagnostic Accuracy of Pulse Pressure Variations for the Prediction of Fluid Responsiveness: The “Gray Zone” Approach

Abstract: Background: Respiratory arterial pulse pressure variations (PPV) are the best predictors of fluid responsiveness in mechanically ventilated patients during general anesthesia. However, previous studies were performed in a small number of patients and determined a single cutoff point to make clinical discrimination. The authors sought to test the predictive value of PPV in a large, multicenter study and to express it using a gray zone approach. Methods: The authors studied 413 patients during general anesthesia and mechanical ventilation in four centers. PPV, central venous pressure, and cardiac output were recorded before and after volume expansion (VE). Response to VE was defined as more than 15% increase in cardiac output after VE. The following approaches were used to determine the gray zones: resampled and two-graph receiver operator characteristic curves. The impact of changes in the benefit-risk balance of VE on the gray zone was also evaluated. Results: The authors observed 209 responders (51%) and 204 nonresponders (49%) to VE. The area under receiver operating characteristic curve was 0.89 (95% CI: 0.86– * Associate Professor, Department of Anesthesiology & Perioperative Care, School of Medicine, University of California, Irvine, Irvine, California. † Associate Professor, Department of Anesthesiology and Critical Care Medicine, Centre Hospitalier Universitaire Pitié-Salpêtrière, Paris, France, and Centre for Statistics in Medicine, Wolfson College, University of Oxford, Oxford, United Kingdom. ‡ Associate Professor, Institute of Anesthesiology and Intensive Care Medicine, Triemli City Hospital, Zurich, Switzerland. § Associate Professor, Department of Anesthesiology and Critical Care Medicine, Centre Hospitalier Universitaire Pitié-Salpêtrière. Professor, Department of Anesthesiology and Critical Care, Hôpital Louis Pradel, Lyon, France. # Professor, Department of Anesthesiology and Critical Care Medicine, Centre Hospitalier Universitaire de Lille, Lille, France. Received from the Department of Anesthesiology & Perioperative Care, School of Medicine, University of California, Irvine, Irvine, California. Submitted for publication December 7, 2010. Accepted for publication May 6, 2011. Support was provided solely from institutional and/or departmental sources. Dr. Cannesson is a consultant for Edwards Lifesciences (Irvine, California), Covidien (Boulder, Colorado), Masimo Corp. (Irvine, California), ConMed (Irvine, California), Philips Medical System (Suresnes, France), CNsystem (Vienna, Austria), BMeye (Amsterdam, The Netherlands), and Fresenius Kabi (Sèvres, France). Dr. Le Manach is a consultant for Air Liquide Santé (Paris, France) and received lecture/travel fees from Masimo Corp. and Fresenius Kabi. Dr. Hofer is a consultant for Pulsion Medical Systems (Munchen, Germany), Edwards Lifesciences, and CSL Behring (King of Prussia, Pennsylvania). Dr. Vallet received lecture/travel fees from Masimo Corp., Edwards Lifesciences, Fresenius Kabi, and Baxter Corp. (Deerfield, Illinois). Dr. Tavernier received lecture/travel fees from Masimo Corp. and Fresenius Kabi. Address correspondence to Dr. Cannesson: Department of Anesthesiology and Perioperative Care, University of California, Irvine, 333 City Boulevard West Side, Orange, California 92868-3301. maxime_ cannesson@hotmail.com. This article may be accessed for personal use at no charge through the Journal Web site, www.anesthesiology.org. Copyright © 2011, the American Society of Anesthesiologists, Inc. Lippincott Williams & Wilkins. Anesthesiology 2011; 115:231–41 What We Already Know about This Topic • Applying a gray zone statistical approach to decision-making may increase the utility of diagnostic measures, including pulse pressure variation to predict fluid responsiveness What This Article Tells Us That Is New • Despite a strong predictive value, the gray zone approach applied to pulse pressure variation may be inconclusive in approximately 25% of patients for prediction of fluid responsiveness in mechanically ventilated patients during general anesthesia This article is accompanied by an Editorial View. Please see: De Hert SG: Assessment of fluid responsiveness: Insights in a “gray zone.” ANESTHESIOLOGY 2011; 115:229–30. Anesthesiology, V 115 • No 2 August 2011 231 Downloaded From: http://anesthesiology.pubs.asahq.org/pdfaccess.ashx?url=/data/journals/jasa/931110/ on 01/03/2019 0.92) for PPV, compared with 0.57 (95% CI: 0.54–0.59) for central venous pressure (P 10 ). The gray zone approach identified a range of PPV values (between 9% and 13%) for which fluid responsiveness could not be predicted reliably. These PPV values were seen in 98 (24%) patients. Changes in the cost ratio of VE moderately affected the gray zone limits. Conclusion: Despite a strong predictive value, PPV may be inconclusive (between 9% and 13%) in approximately 25% of patients during general anesthesia. D YNAMIC variables relying on cardiopulmonary interactions have been shown to be the best predictors of fluid responsiveness in patients during general anesthesia and mechanical ventilation. Today, these variables can be continuously monitored using dedicated devices and they can be derived noninvasively from the pulse oximeter waveform. Several studies have suggested that these variables could be used for intraoperative goal-directed fluid management and that this approach may have a beneficial impact on patients’ outcome in terms of a reduction in postoperative complications resulting in a decrease in length of hospital stay. Thus far, studies evaluating the ability of respiratory arterial pulse pressure variations (PPV) to predict fluid responsiveness have been conducted in small samples of selected patient groups from single centers, using a receiver operating characteristic (ROC) curve approach. However, most quantitative tests do not perfectly discriminate between subjects with and without a given status (i.e., fluid responder or nonresponder in the current case), and their results do not allow certainty in the determination of this status for screening purposes. The “gray zone” approach has been proposed to avoid the binary constraint of a “black-or-white” decision of the ROC curve approach that often does not fit the reality of clinical or screening practice. The gray zone technique proposes two cutoffs that constitute the borders of the gray zone. The first cutoff allows exclusion of the diagnosis (fluid responsiveness in the current case) with near certainty (i.e., privilege sensitivity and negative predictive value), whereas the second cutoff is chosen to include the diagnosis with near certainty (i.e., privilege specificity and positive predictive value). Intermediate values included in the gray zone correspond to a prediction not precise enough for diagnostic decision. A second potential limitation of the ROC curve analysis for evaluation of dynamic variables is that most previous studies indicate it necessitates a fixed definition of fluid responsiveness (an increase of more than 10% or 15% in stroke volume [SV] or cardiac output [CO]) after a 250or 500-ml fluid challenge, whereas according to the FrankStarling curve, the response to a given volume load is actually a continuum of values ranging from “no increase” (or even a decrease) to a “large increase” in SV and/or CO. In addition, the benefit-risk balance of fluid administration may vary between patients, and this has never been taken into account in previous analyses of prediction of fluid responsiveness. The application of these approaches to a large population of patients would allow knowing: (1) the proportion of cases within the gray zone, (2) the range of changes in SV or CO that can be expected in these patients when a fluid challenge is presented, and (3) refinement of the definition of thresholds that should be used for PPV-guided management protocols. Thus, the aim of our study was to assess the diagnostic accuracy of PPV for prediction of fluid responsiveness in a large, multicenter study of mixed groups of patients in the perioperative period and to express its predictive value using a gray zone approach. We also studied the impact of fluid responsiveness definition and a model for benefit-risk assessment of fluid administration on the predictive value of PPV. Materials and Methods Institutional review board (Comité de Protection des Personnes Hospices Civils de Lyon, Lyon, France; Comité de Protection des Personnes Paris-Ile de France, France; Comité de Protection des Personnes Nord Ouest, Lille, France; and Institutional Review Board, Triemli City Hospital, Zurich, Switzerland) approvals were obtained. Patients were included either as part of clinical trials (for whom written and informed consents were obtained) or as part of routine clinical care (for whom no randomization and only routine care was performed, so waived informed consent was authorized). Data Collection Four European institutions (Hôpital Louis Pradel, Lyon, France; Hôpital La Pitié-Salpêtrière, Paris, France; Triemli City Hospital, Zurich, Switzerland; and Centre Hospitalier Universitaire de Lille, Lille, France) participated in this study. We defined preload responsiveness evaluation as an intravenous volume load of 500 ml colloid solution given over 10–20 min, immediately preceded and followed (2–5 min later) by hemodynamic measurements, including PPV and CO (or SV), performed with the aim of measuring the change in CO (or SV) induced by volume expansion. Each investigator collected every sequence of preload responsiveness evaluation that was prospectively recorded and available in his own database, provided that (1) the patient was an adult, with no history of arrhythmia, right ventricular failure, valvular heart disease, or intracardiac shunt, (2) he was undergoing general anesthesia, muscle paralysis, and mechanical ventilation in the controlled volume mode, (3) measurements and volume loading were performed in the operati

Monitoring in the intensive care.

Abstract: In critical care, the monitoring is essential to the daily care of ICU patients, as the optimization of patient's hemodynamic, ventilation, temperature, nutrition, and metabolism is the key to improve patients' survival. Indeed, the decisive endpoint is the supply of oxygen to tissues according to their metabolic needs in order to fuel mitochondrial respiration and, therefore, life. In this sense, both oxygenation and perfusion must be monitored in the implementation of any resuscitation strategy. The emerging concept has been the enhancement of macrocirculation through sequential optimization of heart function and then judging the adequacy of perfusion/oxygenation on specific parameters in a strategy which was aptly coined "goal directed therapy." On the other hand, the maintenance of normal temperature is critical and should be regularly monitored. Regarding respiratory monitoring of ventilated ICU patients, it includes serial assessment of gas exchange, of respiratory system mechanics, and of patients' readiness for liberation from invasive positive pressure ventilation. Also, the monitoring of nutritional and metabolic care should allow controlling nutrients delivery, adequation between energy needs and delivery, and blood glucose. The present paper will describe the physiological basis, interpretation of, and clinical use of the major endpoints of perfusion/oxygenation adequacy and of temperature, respiratory, nutritional, and metabolic monitorings.

Impact of a prophylactic strategy on the incidence of nausea and vomiting after general surgery

Abstract: Background This study aimed to evaluate the implementation of a strategy to prevent postoperative nausea and vomiting (PONV) in patients undergoing general surgery. Study design Prospective observational study. Methods A first period was observational. During a second period, a strategy to prevent PONV was based on five risk factors (RF) identified after the first phase. From two RF, antiemetic treatment was given according to the number of RF. The incidence of PONV was recorded in postoperative anaesthesic care unit (PACU) and at the 24th postoperative hour (24 h). Results We prospectively enrolled 823 patients. Implementation of a prophylactic PONV strategy was associated with a decrease of nausea in PACU from 29.9 to 9.8% ( P P P Conclusion Prophylaxis of PONV by the administration of antiemetic treatment according to a strategy based on a local risk score was efficient and associated with a significant decrease of PONV.

Do established prognostic factors explain the different mortality rates in ICU septic patients around the world

Abstract: Background. The aim of this paper was to clarify if previously established prognostic factors explain the different mortality rates observed in ICU septic patients around the world. Methods. This is a sub-study from the PROGRESS study, which was an international, prospective, observational registry of ICU patients with severe sepsis. For this study we included 10930 patients from 24 countries that enrolled more than 100 patients in the PROGRESS. The effect of potential prognostic factors on in-hospital mortality was examined using univariate and multivariate logistic regression. The complete set of data was available for 7022 patients, who were considered in the multivariate analysis. Countries were classified according to country income, development status, and in-hospital mortality terciles. The relationship between countries' characteristics and inhospital mortality was evaluated using linear regression. Results. Mean in-hospital mortality was 49.2%. Severe sepsis in-hospital mortality varied widely in different countries, ranging from 30.6% in New Zealand to 80.4% in Algeria. Classification as developed or developing country was not associated with in-hospital mortality (P=0.16), nor were levels of gross national product per capita (P=0.15). Patients in the group of countries with higher in-hospital mortality had a crude OR for in-hospital death of 2.8 (95% CI 2.5-3.1) in comparison to those in the lower risk group. After adjustments were made for all other independent variables, the OR changed to 2.9 (95% CI 2.5-3.3). Conclusion. Severe sepsis mortality varies widely in different countries. All known markers of disease severity and prognosis do not fully explain the international differences in mortality. Country income does not explain this disparity either. Further studies should be developed to verify if other organizational or structural factors account for disparities in patient care and outcomes. © 2012 EDIZIONI MINERVA MEDICA.

Comment on Rubulotta et al.: Intensive care medicine: finding its way in the “European labyrinth”

Abstract: Dear Editor, We read with interest the Special Article by Rubulotta et al. [1] on the development and future of intensive care medicine (ICM) in Europe. In our view, some of the statements made in the article need clarification. Although we agree that there is wide variability in the duration, quality, and consistency of training, which impedes free movement of specialists between European countries, this has never been shown to have a negative impact on the outcome, quality, or effectiveness of care. The Multidisciplinary Joint Committee in Intensive Care Medicine (MJCICM) was created ‘to harmonise training programmes and achieve minimum standards of training and expertise among the member European Union states’ [2]. It was not created with the aim of facilitating the recognition of ICM as a primary speciality. An important reason why harmonisation is desirable is to ensure the quality, safety, and effectiveness of care. In addition, it should facilitate the free movement of specialists among European countries. This goal can be achieved by harmonising the acquisition of competencies through the Competency-Based Training in Intensive Care Education (CoBaTrICE) programme, and by evaluation at the end of training the competences through a formal examination. The aim of the CoBaTrICE is to optimise care for the critically ill patient by developing common standards of training, independently of the primary speciality. The MJCICM therefore unanimously decided to request that the European authorities should incorporate ICM as a ‘particular qualification’ in the revision of European Directive 2005/36/EC in 2012. A ‘‘particular qualification’’ is an area of expertise in addition to a primary speciality qualification in which extra expertise outside the domain of the primary speciality is required to provide high-quality patient care. The MJCICM has always clearly pleaded for multidisciplinary access to ICM and does not support the idea of ICM becoming a primary speciality. Instead, ICM should be as a particular qualification open to all specialities involved in ICM, as it is already the case in many European countries [3]. Primary speciality status for the discipline, which currently exists in Spain and the UK (UK), is neither necessary nor desirable. In the UK, however, a dual pathway is possible; this means that a qualification in ICM can be obtained either as a primary speciality or as a particular qualification on top of another primary speciality (e.g., anaesthesiology, surgery, or internal medicine). The reasons for this are clear and obvious: firstly, ICM appears to be too complex to be covered by a single medical speciality alone; secondly, separating ICM as a primary speciality would tend to impede mutual communication and collaboration among different professionals with specific knowledge, expertise, and skills; and thirdly, ICM is extremely demanding physically and mentally. Establishing ICM as a primary speciality would disqualify intensivists from working in another specialisation, whereas the ‘particular qualification’ approach allows them to return to their ‘mother disciplines’, rotate back there for a period or allow those working in the mother discipline to participate in the on call system. All parties involved in ICM in European countries should seek an open-minded discussion with the aim of harmonising the required competencies in order to develop ICM and achieve better treatment and safety for future patients in intensive care.

Optimization of oxygen delivery during high-risk surgery: keeping the concept but refining goals for inotrope infusion?

Abstract: We read with great interest the recent study by Lobo and colleagues stating that fluid restriction during optimization of oxygen delivery (DO2) using dobutamine improves patient outcome after major surgery. Previous studies have shown that haemodynamic optimization using either an individualized goal-directed fluid substitution or inotrope to maximize DO2 reduces postoperative morbidity and hospital length of stay. Although the study brings important new insights, we believe however that some limits should be pointed.