Determination Of Cardiac Output Research Articles

A recommendation for the use of electrical biosensing technology in neonatology.

Non-invasive cardiac output monitoring, via electrical biosensing technology (EBT), provides continuous, multi-parameter hemodynamic variable monitoring which may allow for timely identification of hemodynamic instability in some neonates, providing an opportunity for early intervention that may improve neonatal outcomes. EBT encompasses thoracic (TEBT) and whole body (WBEBT) methods. Despite the lack of relative accuracy of these technologies, as compared to transthoracic echocardiography, the use of these technologies in neonatology, both in the research and clinical arena, have increased dramatically over the last 30 years. The European Society of Pediatric Research Special Interest Group in Non-Invasive Cardiac Output Monitoring, a group of experienced neonatologists in the field of EBT, deemed it appropriate to provide recommendations for the use of TEBT and WBEBT in the field of neonatology. Although TEBT is not an accurate determinant of cardiac output or stroke volume, it may be useful for monitoring longitudinal changes of hemodynamic parameters. Few recommendations can be made for the use of TEBT in common neonatal clinical conditions. It is recommended not to use WBEBT to monitor cardiac output. The differences in technologies, study methodologies and data reporting should be addressed in ongoing research prior to introducing EBT into routine practice. IMPACT STATEMENT: TEBT is not recommended as an accurate determinant of cardiac output (CO) (or stroke volume (SV)). TEBT may be useful for monitoring longitudinal changes from baseline of hemodynamic parameters on an individual patient basis. TEBT-derived thoracic fluid content (TFC) longitudinal changes from baseline may be useful in monitoring progress in respiratory disorders and circulatory conditions affecting intrathoracic fluid volume. Currently there is insufficient evidence to make any recommendations regarding the use of WBEBT for CO monitoring in neonates. Further research is required in all areas prior to the implementation of these monitors into routine clinical practice.

Electric polarization catheter for systemic cardiac output

The electrical activity plays a vital role in the physiological functions of live organisms, electrical stimulation has been identified as a promising nonpharmacological technique that can modulate the behavior of cellular network, restore and monitoring critical functions and accelerate tissue healing in vitro and in vivo. The red blood cell (RBC) membrane contains proteins and glycoproteins embedded in a fluid lipid bilayer that confers viscoelastic behavior. Sialylated glycoproteins of the RBC membrane are responsible for a negatively charged surface which creates a repulsive electric zeta potential (ζ)between cells. These charges help prevent the interaction between RBCs and the other cells and especially between each other. The zeta potential is a physical property which is exhibited by all particles in suspension. In this context we present for the first time the invention concerns the field of measurement of physiological parameters for determining cardiac output (CO), plus specifically refers to a new apparatus for determination of cardiac output based on determination of the electrical charges induced on the membrane of the RBC (electrical polarization of red blood cells).

Determination of Cardiac Output in a Porcine Model for Ex Vivo Pulmonary Perfusion.

Due to their physiological similarities to humans, pigs are used as experimental models for ex vivo lung perfusion (EVLP). EVLP is a technique that perfuses lungs that are not suitable for transplantation via an extracorporeal circulation pump to improve their function and increase their viability. Existing EVLP protocols are differentiated by the type of perfusion solution and perfusion flow, which varies from 40%-100% of the estimated cardiac output (CO) according to the body surface area (BSA). Devices for measuring CO use simple physical principles and other mathematical models. Thermodilution in animal models continues to be the reference standard for estimating CO because of its simplicity and ease of reproduction. Therefore, the objective of this study was to reproduce the measurement of CO by thermodilution in pigs and compare its precision and accuracy with those obtained by the BSA, weight, and Fick's method, to establish perfusion flow during EVLP. In 23 pigs, a thermodilution catheter was placed in the right jugular vein, and the carotid artery on the same side was cannulated. Blood samples were obtained for gasometry, and CO was estimated by thermodilution, adjusted body surface area, Fick's principle, and per body weight. The CO obtained by the BSA was greater (p = 0.0001, ANOVA, Tukey) than that obtained by the other methods. We conclude that although the methods used in this study to estimate CO are reliable, there are significant differences between them; therefore, each method must be evaluated by the investigator to determine which meets the needs of the protocol.

Discussion of hemodynamic optimization strategies and the canonical understanding of hemodynamics during biventricular mechanical support in cardiogenic shock: does the flow balance make the difference?

BackgroundMechanical circulatory support (MCS) devices may stabilize patients with severe cardiogenic shock (CS) following myocardial infarction (MI). However, the canonical understanding of hemodynamics related to the determination of the native cardiac output (CO) does not explain or support the understanding of combined left and right MCS. To ensure the most optimal therapy control, the current principles of hemodynamic measurements during biventricular support should be re-evaluated.MethodsHere we report a protocol of hemodynamic optimization strategy during biventricular MCS (VA-ECMO and left ventricular Impella) in a case series of 10 consecutive patients with severe cardiogenic shock complicating myocardial infarction. During the protocol, the flow rates of both devices were switched in opposing directions (+ / − 0.7 l/min) for specified times. To address the limitations of existing hemodynamic measurement strategies during biventricular support, different measurement techniques (thermodilution, Fick principle, mixed venous oxygen saturation) were performed by pulmonary artery catheterization. Additionally, Doppler ultrasound was performed to determine the renal resistive index (RRI) as an indicator of renal perfusion.ResultsThe comparison between condition 1 (ECMO flow > Impella flow) and condition 2 (Impella flow > VA-ECMO flow) revealed significant changes in hemodynamics. In detail, compared to condition 1, condition 2 results in a significant increase in cardiac output (3.86 ± 1.11 vs. 5.44 ± 1.13 l/min, p = 0.005) and cardiac index (2.04 ± 0.64 vs. 2.85 ± 0.69, p = 0.013), and mixed venous oxygen saturation (56.44 ± 6.97% vs. 62.02 ± 5.64% p = 0.049), whereas systemic vascular resistance decreased from 1618 ± 337 to 1086 ± 306 s*cm−5 (p = 0.002). Similarly, RRI decreased in condition 2 (0.662 ± 0.05 vs. 0.578 ± 0.06, p = 0.003).ConclusionsTo monitor and optimize MCS in CS, PA catheterization for hemodynamic measurement is applicable. Higher Impella flow is superior to higher VA-ECMO flow resulting in a more profound increase in CO with subsequent improvement of organ perfusion.Graphical

Decreased erythrocyte aggregation in Glenn and Fontan: univentricular circulation as a rheologic disease model.

In the Fontan palliation for single ventricle heart disease (SVHD), pulmonary blood flow is non-pulsatile/passive, low velocity, and low shear, making viscous power loss a critical determinant of cardiac output. The rheologic properties of blood in SVHD patients are essential for understanding and modulating their limited cardiac output and they have not been systematically studied. We hypothesize that viscosity is decreased in single ventricle circulation. We evaluated whole blood viscosity, red blood cell (RBC) aggregation, and RBC deformability to evaluate changes in healthy children and SVHD patients. We altered suspending media to understand cellular and plasma differences contributing to rheologic differences. Whole blood viscosity was similar between SVHD and healthy at their native hematocrits, while viscosity was lower at equivalent hematocrits for SVHD patients. RBC deformability is increased, and RBC aggregation is decreased in SVHD patients. Suspending SVHD RBCs in healthy plasma resulted in increased RBC aggregation and suspending healthy RBCs in SVHD plasma resulted in lower RBC aggregation. Hematocrit corrected blood viscosity is lower in SVHD vs. healthy due to decreased RBC aggregation and higher RBC deformability, a viscous adaptation of blood in patients whose cardiac output is dependent on minimizing viscous power loss. Patients with single ventricle circulation have decreased red blood cell aggregation and increased red blood cell deformability, both of which result in a decrease in blood viscosity across a large shear rate range. Since the unique Fontan circulation has very low-shear and low velocity flow in the pulmonary arteries, blood viscosity plays an increased role in vascular resistance, therefore this work is the first to describe a novel mechanism to target pulmonary vascular resistance as a modifiable risk factor. This is a novel, modifiable risk factor in this patient population.

EVs derived from physiologically loaded myocardial slices affect remodelling of overloaded myocardial slices

Abstract Introduction Mechanical load is an important determinant of cardiac output, and excessive mechanical load can lead to heart remodelling, and ultimately failure. Cardiac intercellular communication is partially mediated by extracellular vesicles (EVs), which are 30-200 nm sized nanoparticles acting as shuttles of many bioactive cargoes that modulate cell behaviour, such as microRNAs. Living myocardial slices are an ideal platform to study how mechanical load affect intercellular communication through EVs, as they can be manipulated to obtain different degrees of preload and are an organotypic multicellular platform that retains the electrophysiology and extracellular matrix of the adult myocardial tissue. Purpose The aim of the study is to investigate how EVs derived from physiologically-loaded slices modulate the myocardial remodelling of overloaded slices. Methods 300 µm slices were obtained from the left ventricle of 300-350 g male Sprague Dawley rats. Mechanical load was applied by stretching the slices to either 2.2 or 2.4 µm of their sarcomere length, to recapitulate physiological and overloaded condition, respectively. Following 48-hours of biomimetic culture, force-stretch relationship of the slices was assessed, the tissue collected for RNA and protein extraction and the media of physiological slices was harvested for EVs isolation by size exclusion chromatography. Physiological EVs were then applied onto overloaded slices (1x108 EVs/slice) and cultured for 48-hours to assess force-stretch relationship, and protein and mRNA expression associated with cardiac remodelling. Physiological and overloaded EVs content was analysed through a microRNA array. Results Physiological slices had a significantly higher contractility (P < 0.05), higher blood vessel density (P < 0.0001) and lower apoptosis (P<0.01) compared to overloaded slices. Application of physiological EVs on overloaded slices restored their contractility (P<0.05), attenuated apoptosis by reducing protein PARP-1 expression (P<0.05) and reduced blood vessels density loss (P< 0.01), as shown by Isolectin B4 staining and increased mRNA levels of VEGF. microRNAs analysis showed significant downregulation of miR-346 and miR-16-5p and upregulation of miR-143-3p miR-378a-3p in physiological EVs, compared to overloaded. The upregulation or downregulation of these microRNAs was positively associated with cardiac apoptosis and migration of vascular smooth muscle cells. Conclusions Physiological EVs affect remodelling in overloaded slices. This is likely due to an effect on apoptosis or to an indirect effect on endothelial cells. Further validation and mechanistic studies with miRNAs selected candidates may reveal interesting therapeutic targets for heart failure.

Hemodynamic Determinants of Elevated Blood Pressure and Hypertension in the Middle to Older-Age UK Population: A UK Biobank Imaging Study.

Increased systemic vascular resistance and, in older people, reduced aortic distensibility, are thought to be the hemodynamic determinants of primary hypertension but cardiac output could also be important. We examined the hemodynamics of elevated blood pressure and hypertension in the middle to older-aged UK population participating in the UK Biobank imaging studies. Cardiac output, systemic vascular resistance, and aortic distensibility were measured from cardiac magnetic resonance imaging in 31 112 (distensibility in 21 178) participants (46.3% male, mean age±SD 63±7 years). Body composition including visceral adipose tissue volume and abdominal subcutaneous adipose tissue volume were measured in 19 645 participants. Participants with higher blood pressure had higher cardiac output (higher by 17.9±26.6% in hypertensive compared with those with optimal blood pressure) and higher systemic vascular resistance (higher by 11.4±27.9% in hypertensive compared with those with optimal blood pressure). These differences were little changed after adjustment for body size and adiposity. The contribution of cardiac output relative to systemic vascular resistance was more marked in younger compared with older subjects. Aortic distensibility decreased with age and was lower in participants with higher compared with lower blood pressure but with a greater difference in younger compared with older subjects. In the middle to older-aged UK population, cardiac output plays an important role in contributing to elevated mean arterial blood pressure, particularly in younger compared with older subjects. Reduced aortic distensibility contributes to a rise in pulse pressure and systolic blood pressure at all ages.

Cardiac output estimated from an uncalibrated radial blood pressure waveform: validation in an in-silico-generated population.

Background: Cardiac output is essential for patient management in critically ill patients. The state-of-the-art for cardiac output monitoring bears limitations that pertain to the invasive nature of the method, high costs, and associated complications. Hence, the determination of cardiac output in a non-invasive, accurate, and reliable way remains an unmet need. The advent of wearable technologies has directed research towards the exploitation of wearable-sensed data to improve hemodynamical monitoring. Methods: We developed an artificial neural networks (ANN)-enabled modelling approach to estimate cardiac output from radial blood pressure waveform. In silico data including a variety of arterial pulse waves and cardiovascular parameters from 3,818 virtual subjects were used for the analysis. Of particular interest was to investigate whether the uncalibrated, namely, normalized between 0 and 1, radial blood pressure waveform contains sufficient information to derive cardiac output accurately in an in silico population. Specifically, a training/testing pipeline was adopted for the development of two artificial neural networks models using as input: the calibrated radial blood pressure waveform (ANNcalradBP), or the uncalibrated radial blood pressure waveform (ANNuncalradBP). Results: Artificial neural networks models provided precise cardiac output estimations across the extensive range of cardiovascular profiles, with accuracy being higher for the ANNcalradBP. Pearson's correlation coefficient and limits of agreement were found to be equal to [0.98 and (-0.44, 0.53)L/min] and [0.95 and (-0.84, 0.73)L/min] for ANNcalradBP and ANNuncalradBP, respectively. The method's sensitivity to major cardiovascular parameters, such as heart rate, aortic blood pressure, and total arterial compliance was evaluated. Discussion: The study findings indicate that the uncalibrated radial blood pressure waveform provides sample information for accurately deriving cardiac output in an in silico population of virtual subjects. Validation of our results using in vivo human data will verify the clinical utility of the proposed model, while it will enable research applications for the integration of the model in wearable sensing systems, such as smartwatches or other consumer devices.

Modification of a Transvalvular Microaxial Flow Pump for Instantaneous Determination of Native Cardiac Output and Volume

The current Impella CP pump used for mechanical circulatory support (MCS) in patients with cardiogenic shock (CS) cannot assess native cardiac output (CO) and left ventricular (LV) volumes. This data is valuable in facilitating device management and weaning. Admittance technology allows for accurate assessment of cardiac chamber volumes. This study tested the ability to engineer admittance electrodes onto an existing Impella CP pump to assess total and native CO in an instantaneous manner, as well as LV chamber volumes. Impella CP pumps were fitted with four admittance electrodes and placed in the LV of adult swine (n=9) subjected to three different hemodynamic conditions including Impella CP speed adjustments, administration of escalating doses of dobutamine, and microsphere injections into the left main artery to result in cardiac injury. CO by admittance electrodes was calculated from LV volumes and heart rate. In addition, CO was calculated in each instance via thermodilution, continuous CO (CCO) measurement, Fick's principle and aortic velocity-time integral (VTI) by echocardiography. Modified Impella CP pumps were placed in swine LV successfully. CO as determined by admittance electrodes was similar by trend with other methods of CO assessment, corrected for pump speed to calculate native CO, and calculated LV chamber volumes trended as expected in each experimental protocol. We report for the first time that an Impella CP pump can be fitted with admittance electrodes and used to determine total and native CO in various hemodynamic situations. Transvalvular mechanical circulatory support (MCS) devices such as the Impella CP do not have the ability to provide real-time information on native cardiac output (CO) and left ventricular (LV) volumes. This information is critical in device management and weaning in patients with cardiogenic shock (CS). We demonstrate for the first time, an Impella CP pump coupled with admittance electrodes are able to determine native CO, and left ventricle (LV) chamber volumes in multiple different hemodynamic situations such as Impella pump speed adjustments, escalating dobutamine administration, and cardiac injury from microsphere injection.

Advantages and limitations of noninvasive devices for cardiac output monitoring: a literature review.

Individualized hemodynamic optimization often requires cardiac output monitoring, mostly for goal-directed therapy in the operating room and fluid responsiveness assessment in the intensive care unit. Different technologies for noninvasive cardiac output determination have become available over the recent years. It is therefore crucial for care providers to be made aware of the advantages and limitations of those different devices for an appropriate use at the bedside. Nowadays, different noninvasive technologies exist, each with their advantages and limitations, but none are considered interchangeable with bolus thermodilution. Different clinical studies however, emphasize that the trending ability of such devices allows to guide decisions from care providers, and that their use may be associated with improved prognosis, especially in the operating room. Recent studies have also reported their potential use for hemodynamic optimization in specific populations. Noninvasive cardiac output monitoring may have a clinical impact on patient outcomes. Further studies are required to evaluate their clinical relevance, notably in the intensive care unit. Noninvasive monitoring opens up the possibility for hemodynamic optimization in specific or low-risk populations, the benefit of which remains to be assessed.

Quantification of left ventricular ejection fraction and cardiac output using a novel semi-automated echocardiographic method: a prospective observational study in coronary artery bypass patients

BackgroundEchocardiographic quantification of ejection fraction (EF) by manual endocardial tracing requires training, is time-consuming and potentially user-dependent, whereas determination of cardiac output by pulmonary artery catheterization (PAC) is invasive and carries a risk of complications. Recently, a novel software for semi-automated EF and CO assessment (AutoEF) using transthoracic echocardiography (TTE) has been introduced. We hypothesized that AutoEF would provide EF values different from those obtained by the modified Simpson’s method in transoesophageal echocardiography (TOE) and that AutoEF CO measurements would not agree with those obtained via VTILVOT in TOE and by thermodilution using PAC.MethodsIn 167 patients undergoing coronary artery bypass graft surgery (CABG), TTE cine loops of apical 4- and 2-chamber views were recorded after anaesthesia induction under steady-state conditions. Subsequently, TOE was performed following a standardized protocol, and CO was determined by thermodilution. EF and CO were assessed by TTE AutoEF as well as TOE, using the modified Simpson’s method, and Doppler measurements via velocity time integral in the LV outflow tract (VTILVOT). We determined Pearson’s correlation coefficients r and carried out Bland–Altman analyses. The primary endpoints were differences in EF and CO. The secondary endpoints were differences in left ventricular volumes at end diastole (LVEDV) and end systole (LVESV).ResultsAutoEF and the modified Simpson’s method in TOE showed moderate EF correlation (r = 0.38, p < 0.01) with a bias of -12.6% (95% limits of agreement (95%LOA): -36.6 – 11.3%). AutoEF CO correlated poorly both with VTILVOT in TOE (r = 0.19, p < 0.01) and thermodilution (r = 0.28, p < 0.01). The CO bias between AutoEF and VTILVOT was 1.33 l min−1 (95%LOA: -1.72 – 4.38 l min−1) and 1.39 l min−1 (95%LOA -1.34 – 4.12 l min−1) between AutoEF and thermodilution, respectively. AutoEF yielded both significantly lower EF (EFAutoEF: 42.0% (IQR 29.0 — 55.0%) vs. EFTOE Simpson: 55.2% (IQR 40.1 — 70.3%), p < 0.01) and CO values than the reference methods (COAutoEF biplane: 2.30 l min−1 (IQR 1.30 - 3.30 l min−1) vs. COVTI LVOT: 3.64 l min−1 (IQR 2.05 - 5.23 l min−1) and COPAC: 3.90 l min−1 (IQR 2.30 - 5.50 l min−1), p < 0.01)).ConclusionsAutoEF correlated moderately with TOE EF determined by the modified Simpson’s method but poorly both with VTILVOT and thermodilution CO. A systematic bias was detected overestimating LV volumes and underestimating both EF and CO compared to the reference methods.Trial registrationGerman Register for Clinical Trials (DRKS-ID DRKS00010666, date of registration: 08/07/2016).

The Influence of Methods for Cardiac Output Determination on the Diagnosis of Precapillary Pulmonary Hypertension: A Mathematical Model.

precapillary pulmonary hypertension (PH, PcPH) is now defined as a mean pulmonary artery pressure (mPAP) &gt; 20 mmHg, a pulmonary artery wedge pressure (PAWP) ≤ 15 mmHg and a pulmonary vascular resistance (PVR) &gt; 2 WU. For PVR calculation, the measurement of cardiac output (CO) is necessary. It is generally measured using thermodilution. However, recent data showed that the agreement with direct Fick method, historically the gold standard, is less than previously reported. We aimed to create a mathematical model that calculated the probability of being classified differently (PcPH or unclassified PH) if CO measured by direct Fick was used instead of thermodilution for any individual patients with a mPAP &gt; 20 mmHg and a PAWP ≤ 15 mmHg. The model is based on Bland and Altman analysis with a normally distributed difference of cardiac output, fixed 1.96 standard deviation of bias, bias and physiological cardiac output limits. Following a literature review of the studies comparing CO measured with direct Fick and thermodilution, we fixed the 1.96 standard deviation of bias at 2 L/min, bias at 0 L/min and physiological resting CO limits between 1.3 L/min and 10.2 L/min. This model can help the clinician to evaluate the potential benefit of measuring CO using direct Fick during the diagnostic work-up and its utility in confirming or ruling out a diagnosis of PcPH in any given patient with a mPAP &gt; 20 mmHg and a PAWP ≤ 15 mmHg.

Association of low mechano-energetic efficiency and prognosis in liver cirrhosis.

In cirrhosis, cardiac systolic dysfunction as part of cirrhotic cardiomyopathyaffects prognosis. Myocardial mechano-energetic efficiency (MEE) is an estimate of left ventricular performance. In this study we investigated the relation of MEE to patient characteristics and its impact on survival in patients with cirrhosis. We included 283 patients with cirrhosis of different severity according to the Child-Pugh classifications (A/B/C: 106/87/90). All patients had a liver vein catheterization and a hemodynamic investigation performed including determination of cardiac output (CO), stroke volumeand heart rate (HR). These data were used to assess MEE, which was defined as (stroke volume/HR) × 1.666. Eighty-nine percent of patients had portal hypertension (hepatic venous pressure gradient >5 mmHg) and 80% indications of hyperdynamic circulatory state (increased CO and HR). There was no difference in MEE in Child-Pugh class C patients (2.03) versus Child-Pugh class A (1.98) and B (2.05) patients. In Child-Pugh class C patients, low MEE was associated with a poorer prognosis. In our study, MEE does not seem to be associated with severity of the liver disease, but in patients with advanced disease low MEE is associated with a poorer prognosis. The prognostic impact of MEE should be further investigated.

TCT-67 Modification of the Impella Device for Instantaneous Determination of Native Left Ventricular Cardiac Output and Volume

TCT-67 Modification of the Impella Device for Instantaneous Determination of Native Left Ventricular Cardiac Output and Volume

Non-Invasive Cardiac Output Determination Using Magnetic Resonance Imaging and Thermodilution in Pulmonary Hypertension.

Magnetic resonance imaging (MRI) can be used to measure cardiac output (CO) non-invasively, which is a paramount parameter in pulmonary hypertension (PH) patients. We retrospectively compared stroke volume (SV) obtained with MRI (SVMRI) in six localisations against SV measured with thermodilution (TD) (SVTD) and against each other in 24 patients evaluated in our PH centre using Bland and Altman (BA) agreement analyses, linear correlation, and intraclass correlation (ICC). None of the six tested localisations for SVMRI reached the predetermined criteria for interchangeability with SVTD, with two standard deviations (2SD) of bias between 24.1 mL/beat and 31.1 mL/beat. The SVMRI methods yielded better agreement when compared against each other than the comparison between SVMRI and SVTD, with the best 2SD of bias being 13.8 mL/beat. The inter-observer and intra-observer ICCs for COMRI were excellent (inter-observer ICC between 0.889 and 0.983 and intra-observer ICC between 0.991 and 0.999). We could not confirm the interchangeability of SVMRI with SVTD based on the predetermined interchangeability criteria. The lack of agreement between MRI and TD might be explained because TD is less precise than previously thought. We evaluated a new method to estimate CO through the pulmonary circulation (COp) in PH patients that may be more precise than the previously tested methods.

Role of medical management of cardiogenic shock in the era of mechanical circulatory support.

The goal of this review is to summarize the current knowledge on the role of medical management of cardiogenic shock in the era of mechanical circulatory support based on important lessons from clinical trials and routine clinical practice, with a focus on providing practical recommendations that can improve contemporary in-hospital management. Despite an increasing number of invasive therapies being used to manage cardiogenic shock, evidence-based treatment regimens known to improve outcomes are limited. Medical management of cardiogenic shock includes pharmacological interventions aimed at optimizing determinants of cardiac output-contractility, preload, afterload, and heart rate. In this regard, inotropes and vasopressors remain cornerstone therapies for the management of cardiogenic shock. Norepinephrine has shown potential vasopressor advantage with compared with dopamine, and although milrinone and dobutamine are both considered appropriate first-line inotropes, there is limited data to guide selection, and a recent randomized clinical trial found no significant differences in the treatment of cardiogenic shock. In the absence of an evidence-based management approach to cardiogenic shock, clinical guidelines are based on expert opinion and routine clinical practice patterns. Further studies focusing on clinical outcomes among specific cardiogenic shock phenotypes are needed to better assess the clinical efficacy of these agents.

COMPARISON OF PERIOPERATIVE SEDATION WITH DEXMEDETOMIDINE AND PROPOFOL IN PATIENTS ON MECHANICAL VENTILATION WITH THORACIC AND ABDOMINAL SURGERY

Background: Sedatives used during thoracic and abdominal surgery may affect hemodynamics, patient extubation time, length of stay in the intensive care unit, and the incidence of delirium.&#x0D; Aim: Perioperative assessment of the level sedation with propofol and dexmedetomidine, their effect on hemodynamics with determination of non-invasive cardiac output (esCCO), extubation time, duration of stay in ICU department and frequency of postoperative delirium.&#x0D; Methods: The study included 121 patients over 18 years of age who underwent thoracic and abdominal surgery and received dexmedetomidine or propofol infusion for sedation in the perioperative period. The main result of the study was the determination of extubation time and indicators of non-invasive monitoring of hemodynamics with measurement of cardiac output (esCCO) using the Nihon Kohden monitor. Secondary results of the study were the length of stay in the intensive care unit and hospital, the frequency of delirium.&#x0D; Results. Dexmedetomidine usage (n=52) as an intraoperative and postoperative sedative as opposed to propofol (n=69) was associated with a higher probability of extubation (HR=1.65, 95% CI =1.23–2.21, P=0.001). The longer duration of the operation was associated with a decrease in the probability of extubation (HR=0.83, 95% CI=0.62-0.94, P=0.029), and elderly patients were less likely to rapid extubation (HR=0.73; 95% CI=0.62-0.94, P=0.005). Baseline noninvasive cardiac output parameters of propofol and dexmedetomidine patients were 5.9±1.1 l/min and 6.1±0.6 l/min, respectively. At the end of the operation, the CO values were lower than baseline in patients in the propofol and dexmedetomidine groups by 11.9 % and 6.6 %, respectively. There was no significant association between dexmedetomidine use and length of stay in intensive care, or discharge from hospital (P=0.99 and P=0.54, respectively) and the incidence of delirium in ICU department (P=0.25).&#x0D; Conclusion: Perioperative use of dexmedetomidine was associated with earlier extubation in patients who underwent thoracic and abdominal surgery, without affecting the length of stay in the intensive care unit and hospital. The duration of the operation, old age and the appearance of delirium are the leading factors that contributed to the prolongation of ventilation time. Given the less pronounced depressant effect on noninvasive cardiac output, dexmedetomidine-based perioperative sedation regimens may be an alternative to propofol-based regimens to reduce extubation time

Changes in stroke volume variation and cardiac index during open major bowel surgery.

Stroke volume variation (SVV) is a dynamic indicator of preload, which is a determinant of cardiac output. Aims: Aim of this study was to evaluate the relationship between changes in SVV and cardiac index (CI) in patients with normal left ventricular function undergoing major open abdominal surgery. Patients undergoing major open abdominal surgery were monitored continuously with FloTrac® to measure SVV and CI along with standard monitoring. Both SVV and CI were noted at baseline and every 10 min thereafter till the end of surgery and were observed for concurrence between the measurements. 1800 pairs of measurement of SVV and CI were obtained from 60 patients. Mean SVV and CI (of all patients) measured at different time points of measurement showed that as SVV increased with time, the CI dropped correspondingly. When individual readings of CI and SVV were plotted against each other, the scatter was found to be wide, reiterating the lack of agreement between the two parameters (R2 = 0.035). SVV >13% suggesting hypovolemia was found at 207 time points. Of these, 175 had a CI >2.5 L/min/m2 and only 32 patients had a CI <2.5 L/min/m2. SVV, a dynamic index of fluid responsiveness can be used to monitor patients expected to have large fluid shifts during major abdominal surgery. It is very specific and has a high negative predictive value. When SVV increases, CI is usually maintained. Since many factors affect SVV and CI, any increase in SVV >13%, must be correlated with other parameters before administration of the fluid challenge.

Perioperative Hemodynamic Monitoring: An Overview of Current Methods.

Perioperative hemodynamic monitoring is an essential part of anesthetic care. In this review, we aim to give an overview of methods currently used in the clinical routine and experimental methods under development. The technical aspects of the mentioned methods are discussed briefly. This review includes methods to monitor blood pressures, for example, arterial pressure, mean systemic filling pressure and central venous pressure, and volumes, for example, global end-diastolic volume (GEDV) and extravascular lung water. In addition, monitoring blood flow (cardiac output) and fluid responsiveness (preload) will be discussed.

Renal Function and Pulmonary Fluid Balance in Porcine Models of Acute Lung Injury

Managing pulmonary edema is critical to maintaining blood oxygenation and perfusion for adequate tissue oxygen delivery after acute lung injury. While it is well recognized that renal failure often leads to complications of nephrogenic pulmonary edema, how the regulation of lung fluid is changed during altered renal function in conditions of traumatic injury is poorly understood. We hypothesized that control of lung water balance after a traumatic blunt force lung injury accompanied by a renal response to hemorrhage and hypotension would be different than after simple disruption of the alveolar-capillary liquid barrier interface. Hence, we compared the changes in effective lung water index (ELWI, measured by the Pulse Ion Contour Cardiac Output (PICCO), Getinge) method in a pig model of Traumatic Acute Lung Injury (TALI, n=9), and a model of diffuse alveolar-capillary barrier disruption with oleic acid (OA, n=5), versus a control group (n=10). Anesthetized, mechanically ventilated, Yorkshire cross male and female pigs (body weight 27.0 +/- 0.6 kg) were catheterized with a Swan Ganz catheter for measurement of pulmonary artery pressure and cardiac output determination by thermodilution. Pulmonary function, hemodynamics, and urinary output were examined before and after localized blunt right chest trauma (TALI), or oleic acid injection into the main pulmonary artery (OA 0.3 ml in 50% w/v ethanol). Pulmonary vasoconstriction was induced in the acute lung injury groups as indicated by an increase in pulmonary to systemic vascular resistance ratios in TALI (0.37 +/- 0.03) and OA (0.34 +/-0.08) compared to controls (0.21+/-0.02). TALI resulted in a decrease in mean arterial pressure (MAP, 46+/-4 mmHg) compared to controls (60 +/-2 mmHg) or OA (62+/-3 mm Hg). In all groups ELWI remained steady compared to pre-injury baseline. In the OA and control groups, circulating vasopressin decreased over the time course of the experiment (p<0.01) but did not decrease in the TALI group in accordance with the injury-induced hemorrhage and decreased MAP. Accordingly, urine flow decreased in the TALI group compared to OA and controls. Fractional excretion of water decreased in the OA and control groups, (p<0.01) but remained unchanged in TALI, indicating retention of water in OA and controls compared to TALI. The overall maintenance of ELWI despite differences in renal water handling in TALI compared to controls suggest that protection against pulmonary edema needs to be considered in treatment of hypotension with fluid resuscitation in traumatic lung injury.