Pulse Contour Cardiac Output Research Articles

Helmet Noninvasive Mechanical Ventilation in Patients With Acute Postoperative Respiratory Failure

The physiological and clinical effects of noninvasive ventilation (NIV) on acute postoperative respiratory failure are relatively unknown. The aim of this study was to determine the prediction factors for failure in the use of NIV with a helmet in this context. This was a prospective observational study. The use of NIV was assessed for a period of 2 years in a postoperative ICU. Demographic data were collected, as well as acute respiratory failure (ARF) and arterial gas readings. Hemodynamic changes were assessed using pulse contour cardiac output technology, and the clinical development of subjects was recorded. All subjects who developed ARF were treated using NIV as their primary care, depending on whether the technique was successful or the subject required intubation. The risk factors that determined failure in the application of NIV were subsequently determined. Of the 99 subjects presenting with postoperative ARF treated with NIV using a helmet, 74 did not require intubation (74.7%). Following a multivariate analysis using logistic regression, we determined that there are 3 independent risk factors for the failure of NIV. Three factors were associated with respiratory failure: ARDS, pneumonia, and lack of improvement with NIV in 1 hour (increase in the P(aO(2))/F(IO(2))). NIV using a helmet could provide an effective alternative to conventional ventilation in selected patients with postoperative ARF.

Transpulmonary thermodilution for evaluating respiratory function in swine after severe acute dichlorvos poisoning

Objective In order to extrapolate the respiratory dysfunction of patients in early stage of acute organophosphorus pesticide poisoning (AOPP),transpulmonary thermodilution technique was used in swine models of severe acute dichlorvos poisoning (SADP) to evaluate respiratory function.Methods Twenty healthy female swine were randomly divided into dichlorvos ( n =7 ),atropine ( n =7 ) and control (n =6) groups.In the dichlorvos group,the swine were administered with 80％ emulsified dichlorvos (100mg/kg) via the gastric tube toinduce SADP.In the atropine group,swinewere administered with dichlorvos,and 0.5h later,atropine was injected to obtain and maintain atropinization.The swine of control group were administered with saline solution instead.Arterial and venous blood samples were collected 0,0.5,1,2,4 and 6 hours after modeling for blood gas analysis and detecting acetylcholinesterase levels.Both extravascular lung water index (EVLWI) and pulmonary vascular permeability index ( PVPI ) were measured by using PiCCO (pulse indicator continuous cardiac output ). At the termination of the experiment,the animals were sacrificed and the lung wet/dry weight ratio was determined and histopathological changes of lung tissue were also observed under microscope.Results In the dichlorvos group,EVLWI and PVPI were substantially increased from 0.5 h to 6 h after modeling but PaO2/FiO2 decreased from 0-6 h after modeling.In the atropine group,EVLWI and PVPI increased initially,but then they decreased 1 h afterwards and PaO2/FiO2 was also gradually decreased from 0-1 h.In both dichlorvos group and atropine group,the EVLWI was negatively correlated with PO2/FiO2 and positively correlated with PVPI.Compared with the control group,the lung wet/dry weight ratio increased markedly in the dichlorvos group and mildly increased in the atropine group.Meanwhile,the histopathological changes of lung tissue were obvious in the dichlorvos group and mild in the atropine group.Conclusions SADP swine experienced substantial changes in respiratory function. EVLWI was a reliable and valuable indicator for evaluating respiratory function in the early stage of AOPP. Key words: Dichlorvos poisoning; Extravascular lung water index (EVLWI); Pulmonary vascular permeability index (PVPI); Respiratory function; Transpulmonary single thermodilution; Pulse contour cardiac output (PiCCO); Acute organophosphorus pesticide poisoning (AOPP); Model

Pulse contour cardiac output monitoring is less reliable in critically ill children

Intermittent cardiac output measurement using the transpulmonary thermodilution (TPTD) method is considered to be the gold standard in young children but a validated continuous cardiac output technique is not available in these patients. We compared the continuous pulse contour cardiac output (PCCO) measurements with the TPTD method in critically ill children.

Negative- versus positive-pressure ventilation in intubated patients with acute respiratory distress syndrome

IntroductionRecent experimental data suggest that continuous external negative-pressure ventilation (CENPV) results in better oxygenation and less lung injury than continuous positive-pressure ventilation (CPPV). The effects of CENPV on patients with acute respiratory distress syndrome (ARDS) remain unknown.MethodsWe compared 2 h CENPV in a tankrespirator ("iron lung") with 2 h CPPV. The six intubated patients developed ARDS after pulmonary thrombectomy (n = 1), aspiration (n = 3), sepsis (n = 1) or both (n = 1). We used a tidal volume of 6 ml/kg predicted body weight and matched lung volumes at end expiration. Haemodynamics were assessed using the pulse contour cardiac output (PiCCO) system, and pressure measurements were referenced to atmospheric pressure.ResultsCENPV resulted in better oxygenation compared to CPPV (median ratio of arterial oxygen pressure to fraction of inspired oxygen of 345 mmHg (minimum-maximum 183 to 438 mmHg) vs 256 mmHg (minimum-maximum 123 to 419 mmHg) (P < 0.05). Tank pressures were -32.5 cmH2O (minimum-maximum -30 to -43) at end inspiration and -15 cmH2O (minimum-maximum -15 to -19 cmH2O) at end expiration. NO Inspiratory transpulmonary pressures decreased (P = 0.04) and airway pressures were considerably lower at inspiration (-1.5 cmH2O (minimum-maximum -3 to 0 cmH2O) vs 34.5 cmH2O (minimum-maximum 30 to 47 cmH2O), P = 0.03) and expiration (4.5 cmH2O (minimum-maximum 2 to 5) vs 16 cmH2O (minimum-maximum 16 to 23), P =0.03). During CENPV, intraabdominal pressures decreased from 20.5 mmHg (12 to 30 mmHg) to 1 mmHg (minimum-maximum -7 to 5 mmHg) (P = 0.03). Arterial pressures decreased by approximately 10 mmHg and central venous pressures by 18 mmHg. Intrathoracic blood volume indices and cardiac indices increased at the initiation of CENPV by 15% and 20% (P < 0.05), respectively. Heart rate and extravascular lung water indices remained unchanged.ConclusionsCENPV with a tank respirator improved gas exchange in patients with ARDS at lower transpulmonary, airway and intraabdominal pressures and, at least initially improving haemodynamics. Our observations encourage the consideration of further studies on the physiological effects and the clinical effectiveness of CENPV in patients with ARDS.

Abstract 8110: Dobutamine versus Mirlinone for Intensive Hyperdynamic Therapy to Relieve Focal Cerebral Ischemia Caused by Vasospasm after Subarachnoid Hemorrhage

Therapeutic hemodynamic augmentation by increasing cardiac output (CO) is a valuable method of elevating cerebral blood flow and oxygenation in the dysautoregulated vascular territories affected by vasospasm after subarachnoid hemorrhage (SAH). We prospectively assessed the effect of hyperdynamic therapy with dobutamine (DOB) or milrinone (MIL) on regional cerebral oxygenation (rSO 2 ) for reversing vasospasm-induced cerebral ischemia, using an integrative monitoring incorporated with uncalibrated pulse contour CO analysis and multi-channel near-infrared spectroscopy. One-hundred ten SAH patients diagnosed to have clinical deterioration due to vasospasm were assigned to receive hemodynamic augmentation with DOB or MIL (n=55 per each group). For hyperdynamic therapy, each inotrope was initiated at low dose (DOB: 3 μg/kg/min; MIL 0.15 μg/kg/min) and then increased in each dose increment until resolution of the symptoms unless any adverse effects occur during the therapy, based on our predefined hemodynamic regimen to induce similar dose-related increase in CO. Real-time CO and rSO 2 changes in conjunction with the assessment of neurological improvements were compared. A total of 418 dose increment challenges (DOB, n=192; MIL, n=226) were performed. In spasm-affected territories, decreased and/or fluctuating rSO 2 was detected compared with recordings in other brain region. Patients who exhibited rapid elevation of CO by each challenge had subsequent uptake and stabilization of rSO 2 . The responses (total number and degree of neurological improvements) were more significant in patients treated with DOB than those treated with MIL ( P &lt; 0.05), although tachycardia that may affect stroke volume depression during the DOB therapy was more evident (DOB 27% vs. MIL 9%). Area under the ROC curve to predict rSO 2 elevation or neurological improvement for both drug groups were significant ( P &lt; 0.0001) and the values were significantly greater in DOB than in MIL ( P &lt; 0.05). In conclusion, DOB can provide more effective hemodynamic augmentation in relieving focal cerebral ischemia in patients suffering from vasospasm after SAH. MIL is also effective in the hyperdynamic therapy but may be used as a second line in a patient subgroup where DOB was contraindicated.

The evaluation of the effect of body positioning on intra-abdominal pressure measurement and the effect of intra-abdominal pressure at different body positioning on organ function and prognosis in critically ill patients

PurposeCurrent literatures confirmed the widespread and frequent development of both intra-abdominal hypertension (IAH) and abdominal compartment syndrome (ACS) among the critically ill with a significant associated risk of organ failure and increased mortality. The 2004 International ACS Consensus Conference committee proposed that intra-abdominal pressure (IAP) be measured in complete supine position; however, the supine position of intensive care unit (ICU) patients (<30° of bed increase) presented a significant risk for ventilator-associated pneumonia. Therefore, the potential contribution of head of bed (HOB) position in elevating IAP should be considered. The purpose of this study was to evaluate the effect of body positioning on IAP measurement and the effect of IAP at different body positions on organ function and prognosis in critically ill patients. Materials and MethodsA prospective cohort study to investigate the effect of different patient positioning on IAP, organ function, and prognosis was conducted on 88 patients admitted to a medical-surgical ICU. On admission, patients' epidemiological data and risk factors for IAH were studied; daily mean IAPs, abdominal perfusion pressure, filtration gradient, Acute Physiology and Chronic Health Evaluation II score, sequential organ failure assessment score, and multiple organ dysfunction scores were registered; next, conventional hemodynamic variables, intrathoracic blood volume index, global end-diastolic volume index and extravascular lung water using the pulse contour cardiac output system were recorded. Intra-abdominal pressures were recorded through a bladder catheter every 4 hours on the first day. Intra-abdominal pressure was measured with the patient HOB increases from 0° to 45°. Mean arterial pressure was recorded simultaneously, whereas abdominal perfusion pressure and filtration gradient (FG) were also calculated simultaneously. ResultsThe main results of this study were the incidence of IAH (28.4%) and ACS (2.3%) in ICU patients; the significant and independent relationship between IAP and HOB increases. Considering the absolute numbers of IAP, the HOB of 10° and 20° showed slight differences, whereas that of 30° and 45° showed clinically significant differences; HOB elevation was associated with clinically significant decreases in abdominal perfusion pressure and FG; patients with IAH were prone to the development of shock and multiple organ dysfunction syndrome and exhibited significantly lower intrathoracic blood volume index and global end-diastolic volume index and higher extravascular lung water. ConclusionsThere is a significant and independent relationship between IAP and HOB positioning in critically ill patients, with the HOB of 30° and 45° showing significant difference. Abdominal perfusion pressure and FG are significantly decreased when the patient's HOB is elevated. The potential contribution of body position in elevating IAP should be considered in critically ill patients with the risk of IAH and ACS.

Disagreement between pulse contour analysis and transpulmonary thermodilution for cardiac output monitoring after routine therapeutic interventions in ICU patients with acute circulatory failure

The present prospective study was aimed at assessing the reliability of the pulse contour method for measuring cardiac output (CO) after different routinely used therapeutic interventions that can influence vascular compliance and systemic vascular resistances in ICU patients (fluid challenges, changes in norepinephrine or dobutamine infusion rates and changes in ventilatory settings). In ICU patients requiring CO monitoring, transpulmonary thermodilution CO (COTD) and pulse contour CO (COPC) were measured with a PiCCO device after therapeutic manoeuvre-free periods (≤ and >1 h) and after therapeutic interventions without recalibration. Three hundred fifty-two sets of CO measurement pairs in 63 ICU patients were performed. The biases (and percentage errors) between COPC and COTD for the overall paired measurement, therapeutic manoeuvre-free periods and therapeutic manoeuvres were 0.20 ± 1.09 (33%), -0.01 ± 0.93 (29%) and 0.37 ± 1.18 (34%), respectively. The percentage errors were 36 and 39% for fluid challenges and changes in norepinephrine infusion rate, respectively. In ICU patients requiring therapeutic interventions, COPC is frequently in disagreement with COTD.

Hemodynamic monitoring by transpulmonary thermodilution and pulse contour analysis in critically ill children

To summarize the physiologic principles underlying the hemodynamic monitoring using the PiCCO device (Pulsion, Munich, Germany) incorporating the transpulmonary thermodilution technique, the pulse contour cardiac output, and estimation of the arterial pressure variation method. Analysis and review of the current literature. A MEDLINE-based literature search using the key words transpulmonary thermodilution, pulse contour analysis, cardiac output, animal models, and child. The bias and precision of cardiac output measured by transpulmonary thermodilution are reliable. The reproducibility for repeated measurements is approximately 5% and the percentage error is approximately 15%. Transpulmonary thermodilution may adequately track changes in cardiac output in animals submitted to hypovolemic conditions and during volume loading. Conversely, data from experimental and clinical studies suggest that continuous monitoring of cardiac output using pulse contour analysis requires careful interpretation because periodic recalibration with transpulmonary thermodilution is necessary. Transpulmonary thermodilution-derived static indicator of cardiac preload (global end-diastolic volume, intrathoracic blood volume) may be more sensitive than conventional measurements of vascular filling pressure. However, the value of stroke volume variation or pulse pressure variation have not been evaluated in pediatric patients. Further studies are needed to determine whether theoretical assumptions underlying the measurement of extravascular lung water are valid in children. The PiCCO device may be a useful adjunct for hemodynamic monitoring in critically ill children. Further studies are needed to clarify the reliability and clinical value of pulse contour method and extravascular lung water measurement.

Evaluation of a New Software Version of the FloTrac/Vigileo (Version 3.02) and a Comparison with Previous Data in Cirrhotic Patients Undergoing Liver Transplant Surgery

Reliable cardiac output monitoring is particularly useful in the cirrhotic patient undergoing liver transplant surgery, because cirrhosis of the liver is associated with a vasodilated and high output state, known as cirrhotic cardiomyopathy, that challenges the reliability of pulse contour cardiac output technology. The contractility of the ventricle in cirrhosis is impaired, which is tolerated even though the ejection fraction and cardiac output are elevated because of the low peripheral resistance. However, during surgery the cirrhotic patient can decompensate because of the physiological changes and stress of surgery. Recently, we showed that the FloTrac/Vigileo™ failed to perform in cirrhotic patients undergoing transplant surgery. In response, the company upgraded their software. Therefore, we have assessed the accuracy and reliability of this new third-generation (version 3.02) FloTrac/Vigileo algorithm software in the same setting. The cardiac index was measured simultaneously by single-bolus thermodilution (CI(TD)), using a pulmonary artery catheter, and pulse contour analysis, using the FloTrac/Vigileo (CI(V)). Readings were made at 10 time points during and after liver transplant surgery in 21 patients. Comparisons with data from our 2009 study, which used second-generation (version 01.10) software, were also made. Our new data show that version 3.02 software significantly reduced the adverse effect on pulse contour cardiac output reading bias in low peripheral resistance states, and thus improves the overall precision and trending ability of the system. Regression analysis between CI(TD) and CI(V) showed that the correlation was moderate (r =0.67, 95% confidence interval, 0.40 to 0.86). The Bland and Altman analysis showed that bias was 0.4 L.min(-1) · m(-2), and the percentage error was 52% (95% confidence interval, 49% to 55%). Trending ability of the new software also was improved but was still well below the current benchmarks. The new software (version 3.02) provided substantial improvements over the previous versions with better overall precision and trending ability. Further algorithm refinements will increase this technology's reliability to be extensively used in the highly complex setting of cirrhotic patients undergoing liver transplantation.

Evaluation of mean systemic filling pressure from pulse contour cardiac output and central venous pressure

The volemic status of a patient can be determined by measuring mean systemic filling pressure (Pmsf). Pmsf is obtained from the venous return curve, i.e. the relationship between central venous pressure (Pcv) and blood flow. We evaluated the feasibility and precision of Pmsf measurement. In ten piglets we constructed venous return curves using seven 12 s inspiratory holds transiently increasing Pcv to seven different steady state levels and monitored the resultant blood flow, by pulse contour (COpc) and by flow probes around the pulmonary artery (COr) and aorta (COl). Pmsf is obtained by extrapolation of the venous return curve to zero flow. Measurements were repeated to evaluate the precision of Pmsf. During the inspiratory holds, 133 paired data points were obtained for COr, COl, COpc and Pcv. Bland-Altman analysis showed no difference between COr and COl, but a small significant difference was present between COl and COpc. All Pcv versus flow (COl or COpc) relationships were linear. Mean Pmsf was 10.78 with COl and 10.37 mmHg with COpc. Bland-Altman analysis for Pmsf with COl and with COpc, showed a bias of 0.40 ± 0.48 mmHg. The averaged coefficient of variation for repeated measurement of Pmsf with COl was 6.2% and with COpc 6.1%. During an inspiratory hold pulmonary flow and aortic flow equilibrate. Cardiac output estimates by arterial pulse contour and by a flow probe around the aorta are interchangeable. Therefore, the venous return curve and Pmsf can be estimated accurately by pulse contour methods.

Validation of cardiac output measurement with the LiDCOTM pulse contour system in patients with impaired left ventricular function after cardiac surgery*

After cardiac surgery, patients with low left ventricular ejection fraction probably benefit the most from accurate monitoring of continuous cardiac output. Thirty patients with impaired ventricular function were studied, and intermittent bolus thermodilution and continuous pulse contour (LiDCO plus™) cardiac output compared. Following lithium dilution calibration, a total of 220 paired results were recorded. Thermodilution and LiDCO measurements ranged from 2.3 to 11.0 and 2.6 to 10.8 l.min(-1), respectively. Corresponding means (SD) were 6.1 (1.6) and 6.2 (1.9) l.min(-1), with coefficients of variance of 26 and 31%, respectively. The correlation coefficient was 0.82, bias 0.28 l.min(-1) with upper and lower limits of agreement 1.96 and -1.41 l.min(-1); the percentage error was 27%. LiDCO showed good correlation, marginal bias and acceptable limits of agreement and percentage error. It could therefore potentially replace thermodilution as a means of measuring cardiac output in the ICU, particularly when determination of pulmonary artery pressure is not required.

Selected Abstracts Presented at the 21st Meeting of The European Society for Computing and Technology in Anaesthesia and Intensive Care (ESCTAIC)

SELECTED ABSTRACTS PRESENTED AT THE 21ST MEETING OF THE EUROPEAN SOCIETY FOR COMPUTING AND TECHNOLOGY IN ANAESTHESIA AND INTENSIVE CARE (ESCTAIC) Amsterdam, The Netherlands, 6th–9th October, 2010 Edited by: A. A. van Dusseldorp, C. Boer, D. S. Karbing, L. Krummreich, S. E. Rees, S. A. Loer LIST OF ABSTRACTS Soraya Abbasi: The Role of Physiological Models in Critiquing Mechanical Ventilation Treatments Gracee Agrawal: Real-time Detection of Suppression in EEG Christa Boer: Clinical Experience with Perioperative Non-invasive Beat-to-beat Arterial Blood Pressure Monitoring Nadja Bressan: Infusion Rate Control Algorithm for Target Control Infusion using Optimal Control Chih-Yen Chiang: Rule-based Evaluation for the Patientcontrolled Analgesia Clinical Effectiveness Wolfgang Friesdorf: Professional Design of Clinical Working Systems According to Human Factors Fred de Geus: CAROLA: An Open Source PDMS, After 25 Years Still Experimental? Yori Gidron: The Effects of Stress and Hemispheric Lateralization on Managerial Decisions Johan Groeneveld: Value of Central or Mixed Venous O2 Saturation in Guiding Treatment in the Intensive Care Unit Gabriel M. Gurman: Professional Stress and the Anesthesiologist-how Evident is it? Eliahu Heldman: Salivary Cortisol as a Measure of Professional Stress; An Overview and a Description of a Study with Paramedics Martin Hurrell: Implementation of a Standards-based, CDA-Compliant Anesthesia Record Mathieu Jeanne: Analgesia Nociception Index Online Computation and Preliminary Clinical Test During Cholecystectomy Under Remifentanil-Propofol Anaesthesia Christian Jeleazcov: Pharmacodynamic Modeling of Changes in Pulse Waveform During Induction of Propofol Anaesthesia in Volunteers: Comparison between Invasive and Continuous Non-invasive Measurements of Pulse Pressure Pierre Kalfon: Assessing Performances of Glucose Control Algorithms on a set of Virtual ICU Patients Cor Kalkman: Automation and Automation Surprises: Lessons from Aviation. Should Health Care Brace Itself. Dan S Karbing: Use of the INVENT System for Standardized Quantification of Clinical Preferences Towards Mechanical Ventilator Settings Talma Kushnir: Moods and Burnout Among Physicians: Associations with Prescribing Medications Communicating with Patients, and Referrals for Specialists and Diagnostic Tests Johannes J van Lieshout: Non-invasive Pulse Contour Cardiac Output by Nexfin Technol Egbert Mik: Monitoring Mitochondrial Oxygenation Journal of Clinical Monitoring and Computing (2011) 25:3–43 DOI: 10.1007/s10877-011-9276-2 Springer 2011

Uncalibrated pulse power analysis fails to reliably measure cardiac output in patients undergoing coronary artery bypass surgery

IntroductionUncalibrated arterial pulse power analysis has been recently introduced for continuous monitoring of cardiac index (CI). The aim of the present study was to compare the accuracy of arterial pulse power analysis with intermittent transpulmonary thermodilution (TPTD) before and after cardiopulmonary bypass (CPB).MethodsForty-two patients scheduled for elective coronary surgery were studied after induction of anaesthesia, before and after CPB respectively. Each patient was monitored with the pulse contour cardiac output (PiCCO) system, a central venous line and the recently introduced LiDCO monitoring system. Haemodynamic variables included measurement of CI derived by transpulmonary thermodilution (CITPTD) or CI derived by pulse power analysis (CIPP), before and after calibration (CIPPnon-cal., CIPPcal.). Percentage changes of CI (ΔCITPTD, ΔCIPPnon-cal./PPcal.) were calculated to analyse directional changes.ResultsBefore CPB there was no significant correlation between CIPPnon-cal. and CITPTD (r2 = 0.04, P = 0.08) with a percentage error (PE) of 86%. Higher mean arterial pressure (MAP) values were significantly correlated with higher CIPPnon-cal. (r2 = 0.26, P < 0.0001). After CPB, CIPPcal. revealed a significant correlation compared with CITPTD (r2 = 0.77, P < 0.0001) with PE of 28%. Changes in CIPPcal. (ΔCIPPcal.) showed a correlation with changes in CITPTD (ΔCITPTD) only after CPB (r2 = 0.52, P = 0.005).ConclusionsUncalibrated pulse power analysis was significantly influenced by MAP and was not able to reliably measure CI compared with TPTD. Calibration improved accuracy, but pulse power analysis was still not consistently interchangeable with TPTD. Only calibrated pulse power analysis was able to reliably track haemodynamic changes and trends.

The uncalibrated pulse contour cardiac output during off-pump coronary bypass surgery: performance in patients with a low cardiac output status and a reduced left ventricular function

BackgroundWe compared the continuous cardiac index measured by the FloTrac/Vigileo™ system (FCI) to that measured by a pulmonary artery catheter (CCI) with emphasis on the accuracy of the FCI in patients with a decreased left ventricular ejection fraction (LVEF) and a low cardiac output status during off-pump coronary bypass surgery (OPCAB). We also assessed the influence of several factors affecting the pulse contour, such as the mean arterial pressure (MAP), the systemic vascular resistance index (SVRI) and the use of norepinephrine.MethodsFifty patients who were undergoing OPCAB (30 patients with a LVEF ≥ 40%, 20 patients with a LVEF < 40%) were enrolled. The FCI and CCI were measured and we performed a Bland-Altman analysis. Subgroup analyses were done according to the LVEF (< 40%), the CCI (≤ 2.4 L/min/m), the MAP (60-80 mmHg), the SVRI (1,600-2,600 dyne/s/cm5/m2) and the use of norepinephrine.ResultsThe FCI was reliable at all the time points of measurement with an overall bias and limit of agreement of -0.07 and 0.67 L/min/m2, respectively, resulting in a percentage error of 26.9%. The percentage errors in the patients with a decreased LVEF and in a low cardiac output status were 28.2% and 22.3%, respectively. However, the percentage error in the 91 data pairs outside the normal range of the SVRI was 40.2%.ConclusionsThe cardiac output measured by the FloTrac/Vigileo™ system was reliable even in patients with a decreased LVEF and in a low cardiac output status during OPCAB. Acceptable agreement was also noted during the period of heart displacement and grafting of the obtuse marginalis branch.

Estimation of cardiac output in patients with congestive heart failure by analysis of right ventricular pressure waveforms

BackgroundCardiac output (CO) is an important determinant of the hemodynamic state in patients with congestive heart failure (CHF). We tested the hypothesis that CO can be estimated from the right ventricular (RV) pressure waveform in CHF patients using a pulse contour cardiac output algorithm that considers constant but patient specific RV outflow tract characteristic impedance.MethodIn 12 patients with CHF, breath-by-breath Fick CO and RV pressure waveforms were recorded utilizing an implantable hemodynamic monitor during a bicycle exercise protocol. These data were analyzed retrospectively to assess changes in characteristic impedance of the RV outflow tract during exercise. Four patients that were implanted with an implantable cardiac defibrillator (ICD) implementing the algorithm were studied prospectively. During a two staged sub-maximal bicycle exercise test conducted at 4 and 16 weeks of implant, COs measured by direct Fick technique and estimated by the ICD were recorded and compared.ResultsAt rest the total pulmonary arterial resistance and the characteristic impedance were 675 ± 345 and 48 ± 18 dyn.s.cm-5, respectively. During sub-maximal exercise, the total pulmonary arterial resistance decreased (Δ 91 ± 159 dyn.s.cm-5, p < 0.05) but the characteristic impedance was unaffected (Δ 3 ± 9 dyn.s.cm-5, NS). The algorithm derived cardiac output estimates correlated with Fick CO (7.6 ± 2.5 L/min, R2 = 0.92) with a limit of agreement of 1.7 L/min and tracked changes in Fick CO (R2 = 0.73).ConclusionsThe analysis of right ventricular pressure waveforms continuously recorded by an implantable hemodynamic monitor provides an estimate of CO and may prove useful in guiding treatment in patients with CHF.

Pulse Contour Analysis to Assess Hemodynamic Response to Passive Leg Raising

The authors evaluated the ability of 2 pulse contour cardiac output (CO) techniques to track CO changes during passive leg raising (PLR) to assess fluid loading responsiveness. A prospective study. An intensive care unit in a university hospital. Twenty mechanically ventilated postoperative cardiac surgery patients. Thirty-degree PLR. The authors estimated CO by 3 techniques: thermodilution (COtd), arterial pulse power (Coli; LiDCO, London, UK), and pulse contour method (Com; FMS, Amsterdam, The Netherlands) based on uncalibrated Modelflow. The authors measured heart rate (HR), central venous pressure, arterial pulse pressure (PP), systolic pressure (SP), and mean arterial pressure (MAP). Stroke volume (SV), SP, PP, and SV variation (PPV and SVV, respectively) were calculated over 5 breaths. SVV was measured by both LiDCO (SVVli) and Modelflow (SVVm) devices. PLR-induced changes in COtd correlated with COli (p < 0.001) and COm (p < 0.001). Preload dependence was predicted with an area under the ROC curve of 0.968 for ΔCOm, 0.841 for ΔCOli, 0.825 for SVVm, 0.873 for SVVli, 0.808 for PPV, 0.778 for ΔSP, 0.714 for ΔPP, and 0.873 for ΔMAP. Changes in COm, COli, SVV, and PPV track COtd changes during PLR with a high degree of accuracy in sedated, ventilated, postoperative cardiac surgery patients. Changes in pulse contour CO after PLR can be used to predict fluid loading responsiveness.

PiCCO (Pulse Contour Cardiac Output) catheter: The new gold standard for monitoring core temperature during mild hypothermia?

Purpose of the study: Mild hypothermia after cardiac arrest improves neurologic outcome. The temperature site best reflecting core temperature is considered to be the pulmonary artery, yet it is limited by invasiveness. In recent years a femoral arterial thermodilution catheter (PiCCO—Pulse Contour Cardiac Output) has been introduced in clinical practice as a safe and accurate hemodynamic monitoring system, which is able to measure blood temperature.

Pulse contour cardiac output derived from non‐invasive arterial pressure in cardiovascular disease

Pulse contour methods determine cardiac output semi-invasively using standard arterial access. This study assessed whether cardiac output can be determined non-invasively by replacing the intra-arterial pressure input with a non-invasive finger arterial pressure input in two methods, Nexfin CO-trek and Modelflow , in 25 awake patients after coronary artery bypass surgery. Pulmonary artery thermodilution cardiac output served as a reference. In the supine position, the mean (SD) differences between thermodilution cardiac output and Nexfin CO-trek were 0.22 (0.77) and 0.44 (0.81) l.min(-1) , for intra-arterial and non-invasive pressures, respectively. For Modelflow, these differences were 0.70 (1.08) and 1.80 (1.59) l.min(-1) , respectively. Similarly, in the sitting position, differences between thermodilution cardiac output and Nexfin CO-trek were 0.16 (0.78) and 0.34 (0.83), for intra-arterial and non-invasive arterial pressure, respectively. For Modelflow, these differences were 0.58 (1.11) and 1.52 (1.54) l.min(-1) , respectively. Thus, Nexfin CO-trek readings were not different from thermodilution cardiac output, for both invasive and non-invasive inputs. However, Modelflow readings differed greatly from thermodilution when using non-invasive arterial pressure input.

Short-term effectiveness of different volume replacement therapies in postoperative hypovolaemic patients

To examine the kinetics of volume loading with crystalloid and colloid infusions in critically ill patients after major surgery, using the pulse contour cardiac output (PiCCO) monitoring technique. This prospective, randomized, multicentre study of 11 ICUs involved 200 mixed postoperative hypovolaemic patients (50 patients per group) in Hungary. Patients received 10 ml kg of lactated Ringer's solution, succinylated gelatin 4% w/v, 130/0.4 hydroxyethyl starch 6% w/v (HES) or human albumin 5% w/v over 30 min. A complete haemodynamic profile was obtained at 30, 45, 60, 90 and 120 min after baseline. The peak haemodynamic effects, the 120 min changes compared with baseline, the area under the curve (AUC) for the haemodynamic parameters over 120 min and the haemodilution effect of the solutions were analysed. The primary outcome was to compare the AUCs and the secondary outcome was to evaluate the haemodynamic changes at 120 min. There were significant differences in the AUCs of the haemodynamic parameters between colloids and lactated Ringer's solution in the cardiac index and global end-diastolic volume index (GEDVI); human albumin vs. lactated Ringer's solution in stroke volume variation (SVV); and succinylated gelatin, HES vs. lactated Ringer's solution in the oxygen delivery index (DO2I). Colloid infusions (mainly HES and human albumin) at 120 min caused significant changes in central venous pressure, cardiac index, GEDVI, SVV, DO2I and central venous oxygen saturation compared with baseline. The haemodilution effect was significantly greater in colloids vs. lactated Ringer's solution. In postoperative hypovolaemic patients, lactated Ringer's solution can significantly improve haemodynamics at the end of volume loading, but this effect completely disappears at 120 min. Ten millilitres per kilogram of colloid bolus (especially HES) improved the haemodynamics at 120 min; however, this was by only 5-25% compared with baseline. The colloids caused significantly larger AUCs than lactated Ringer's solution, but only in the cardiac index, GEDVI and DO2I, plus human albumin in the SVV.

Tracheal gas insufflation with partial liquid ventilation to treat LPS‐induced acute lung injury in juvenile piglets

Partial liquid ventilation (PLV) with perfluorocarbons (PFC) seems not superior to conventional ventilation clinically. We hypothesized that a combination of continuous tracheal gas insufflation (TGI) with protective strategy of PLV (low dose of PFC, low inflation pressure, moderate inhalation of oxygen and moderate anesthesia) would improve cardiopulmonary function in acute lung injury. Twenty-four healthy juvenile piglets were anesthetized and mechanically ventilated at PEEP of 2 cmH(2)O with a peak inspiratory pressure of 10 cmH(2)O and FIO(2) of 0.4. The piglets were challenged with lipopolysaccharide and randomly assigned to four groups (n = 6 each): (1) mechanical ventilation alone (MV); (2) PLV with perfluorodecalin (10 ml/kg); (3) TGI with continuous airway flow 2 L/min; and (4) combination of PLV and TGI. The outcome was assessed functionally and histologically. All treatments except MV improved pH, PaO(2)/FIO(2), PaCO(2), ventilation efficacy index (VEI) and tidal volume. Both PLV-associated treatments also improved heart rate, respiratory rate, pulse contour cardiac output, systemic vascular resistance, dynamic lung compliance, mean airway resistance and mean airway pressure. The combination group resulted in higher PaO(2)/FIO(2), VEI and a better lung histology score than any other treatments. The new protective strategy may provide a better treatment for sepsis-induced acute lung injury.