Arterial Pulse Contour Analysis Research Articles

Passive leg raising: five rules, not a drop of fluid!

Passive leg raising: five rules, not a drop of fluid!

Characterization of exercise limitations by evaluating individual cardiac output patterns: a prospective cohort study in patients with chronic heart failure.

BackgroundPatients with chronic heart failure (CHF) suffer from exercise intolerance due to impaired central hemodynamics and subsequent alterations in peripheral skeletal muscle function and structure. The relative contribution of central versus peripheral factors in the reduced exercise capacity is still subject of debate. The main purpose was to investigate heterogeneity in the nature of exercise intolerance by evaluating individual cardiac output (Q) patterns. The secondary purpose was to evaluate whether patient and disease characteristics were associated with a central hemodynamic exercise limitation.MethodsSixty-four stable CHF patients performed a symptom limited incremental exercise test with respiratory gas analysis and simultaneous assessment of Q, using a radial artery pulse contour analysis method. A central hemodynamic exercise limitation was defined as a plateau or decline in Q from 90 to 100 % of exercise duration.ResultsData from 61 patients were analyzed. A central hemodynamic exercise limitation was observed in 21 patients (34 %). In these patients, a higher occurrence of a plateau/decrease in oxygen uptake (VO2) (52 % vs 23 %, p = 0.02), stroke volume (SV) (100 % vs. 75 %, p = 0.01) and chronotropic incompetence (31 % vs. 2.5 %, p = 0.01) was observed, while presence of a left bundle branch block (LBBB) occurred significantly less (19 % vs 48 %, p = 0.03) There was no difference in disease characteristics such as etiology, duration, NYHA class, mitral regurgitation or ischemia.ConclusionsThe study revealed considerable heterogeneity in the nature of exercise limitations between moderately impaired CHF patients. In one third of the study population a plateau or decrease in Q towards peak exercise was demonstrated, which is indicative of a central hemodynamic exercise limitation. A central hemodynamic exercise limitation was associated with an impairment to augment stroke volume and heart rate.

The impact of inspiratory pressure on stroke volume variation and the evaluation of indexing stroke volume variation to inspiratory pressure under various preload conditions in experimental animals.

PurposeStroke volume variation (SVV) measures fluid responsiveness, enabling optimal fluid management under positive pressure ventilation. We aimed to investigate the effect of peak inspiratory pressure (PIP) on SVV under various preload conditions in experimental animals and to ascertain whether SVV indexed to PIP decreases the effect.MethodsMild and moderate hemorrhage models were created in nine anesthetized, mechanically ventilated beagle dogs by sequentially removing 10 and then an additional 10 ml/kg of blood, respectively. In all the animals, PIP was incrementally increased by 4 cmH2O, from 5 to 21 cmH2O. SVV was measured by arterial pulse contour analysis. Stroke volume was derived using a thermodilution method, and central venous pressure and mean arterial pressure were also measured.ResultsSVV increased according to PIP with significant correlation at baseline, with mild hemorrhage and moderate hemorrhage. PIP regression coefficients at baseline and in the mild and moderate hemorrhage models were 0.59, 0.86, and 1.4, respectively. Two-way repeated-measures analysis of variance showed that PIP and the degree of hemorrhage had a significant interaction effect on SVV (p = 0.0016). SVV indexed to PIP reflected the hemorrhage status regardless of PIP changes ≥9 cmH2O.ConclusionsPIP is significantly correlated with SVV, even under hypovolemia, and the effect is enhanced with decreasing preload volumes. Compared with SVV, the indexed SVV was less susceptible to higher inspiratory pressures.

An Observational Comparative Study of Cardiac Index Estimated By FloTrac and Intermittent Thermo Dilution in Off-Pump Coronary Artery Bypass Grafting

Objective: The purpose of this study was to determine the correlation between cardiac index (CI) measurements made using intermittent thermodilution (ITD) technique by pulmonary artery catheter (PAC) and arterial pulse-contour analysis by FloTrac. Design: Prospective observational study. Setting: Cardiac surgery unit in a 350 bedded tertiary care hospital in India. Participants: 31 adult patients undergoing elective off-pump coronary artery bypass grafting (OPCABG) Interventions: CI measurements performed by the two different methods at six time points during the surgery (before skin incision, during grafting of left anterior descending artery, obtuse marginal artery and right coronary/ posterior descending artery, after protamine administration and after shifting the patient to recovery room). Measurements and results: The techniques a weak correlation at all six time points during the OPCABG. The mean bias of 0.85 L/min/m2 and precision of 0.55 was found in the study population. The percentage error calculated using Critchley s criteria was found to be 46%. Conclusion: CI measurements obtained using FloTrac showed a limited correlation with those acquired by ITD technique at different stages of OPCABG. Further studies are required in other patient populations and clinical situations.

Feasibility of common carotid artery point of care ultrasound in cardiac output measurements compared to invasive methods.

Cardiac output (CO) measurement in the intensive care unit (ICU) requires invasive devices such as the pulmonary artery (PA) catheter or arterial waveform pulse contour analysis (PCA). This study tests the accuracy and feasibility of point of care ultrasound (POCUS) of the common carotid artery to estimate the CO non-invasively and compare it to existing invasive CO measurement modalities. Patients admitted to the surgical and cardiothoracic ICU in a tertiary university-affiliated academic center during a 4-month period, with invasive hemodynamic monitoring devices for management, were included in this cohort study. Common carotid artery POCUS was performed to measure the CO and the results were compared to an invasive device. Intensivists and ICU fellows, using ultrasound of the common carotid artery, obtained the CO measurements. Images of the Doppler flow and volume were obtained at the level of the thyroid gland. Concurrent CO measured via invasive devices was recorded. The patient cohort comprised 36 patients; 52% were females. The average age was 59±13years, and 66% were monitored via PCA device and 33% via PA catheter. Intraclass correlation coefficient (ICC) analysis demonstrated almost perfect correlation (0.8152) between measurements of CO via ultrasound vs. invasive modalities. The ICC between POCUS and the invasive measurement via PCA was 0.84 and via PA catheter 0.74, showing substantial agreement between the ultrasound and both invasive modalities. Common carotid artery POCUS offers a non-invasive method of measuring the CO in the critically ill population.

Dynamic variables and fluid responsiveness in patients for aortic stenosis surgery.

Aortic stenosis is the most common valvular disease in developed countries, but it carries an increased mortality during non-cardiac surgery underscoring the importance of adequate hemodynamic management. Further, haemodynamic management of patients immediately after surgery for aortic stenosis can be challenging. Prediction of fluid responsiveness using dynamic variables has not been sufficiently studied in patients for aortic stenosis surgery. Observational study evaluating fluid responsiveness on 32 (31 analysed) patients scheduled for aortic valve replacement due to aortic stenosis on mechanical ventilation before and after valve replacement. Increase in stroke volume (oesophagus Doppler) ≥ 15% to a fluid challenge defined fluid responders. Before surgery (31 fluid loads performed in 31 patients), areas under receiver operating characteristics curves (95% confidence intervals) were stroke volume variation (from arterial pulse contour analysis) 0.77 (0.58-0.90), pulse pressure variation 0.75 (0.54-0.90) and Pleth variability index 0.51 (0.31-0.69). After aortic valve replacement (31 fluid loads performed in 23 patients) the values were stroke volume variation 0.90 (0.74-0.98), pulse pressure variation 0.95 (0.80-1.0) and Pleth variability index 0.72 (0.52-0.87). The arterial pressure-based variables had moderate predictive values before valve replacement, but it predicted fluid responsiveness well postoperatively. Pleth variability index did not predict fluid responsiveness preoperatively, and it had a moderate predictive value postoperatively. These results indicate that arterial pressure-based dynamic variables have limited potential to guide fluid therapy in patients with aortic stenosis. Their ability to guide fluid therapy after aortic valve replacement seems better.

Mesure semi-invasive du débit cardiaque basé sur le contour du pouls: étude et analyse

The aim of this review was to provide a meta-analysis of all five of the most popular systems for arterial pulse contour analysis compared with pulmonary artery thermodilution, the established reference method for measuring cardiac output (CO). The five investigated systems are FloTrac/Vigileo(®), PiCCO(®), LiDCO/PulseCO(®), PRAM/MostCare(®), and Modelflow. In a comprehensive literature search through MEDLINE(®), Web of Knowledge (v.5.11), and Google Scholar, we identified prospective studies and reviews that compared the pulse contour approach with the reference method (n=316). Data extracted from the 93 selected studies included range and mean cardiac output, bias, percentage error, software versions, and study population. We performed a pooled weighted analysis of their precision in determining CO in various patient groups and clinical settings. Results of the majority of studies indicate that the five investigated systems show acceptable accuracy during hemodynamically stable conditions. Forty-three studies provided adequate data for a pooled weighted analysis and resulted in a mean (SD) total pooled bias of -0.28 (1.25) L·min(-1), percentage error of 40%, and a correlation coefficient of r=0.71. In hemodynamically unstable patients (n=8), we found a higher percentage error (45%) and bias of -0.54 (1.64) L·min(-1). During hemodynamic instability, CO measurement based on continuous arterial pulse contour analysis shows only limited agreement with intermittent bolus thermodilution. The calibrated systems seem to deliver more accurate measurements than the auto-calibrated or the non-calibrated systems. For reliable use of these semi-invasive systems, especially for critical therapeutic decisions during hemodynamic disorders, both a strategy for hemodynamic optimization and further technological improvements are necessary.

Monitoring the treatment of myocardial stunning syndrome after acute carbon monoxide poisoning using arterial pulse wave analysis: a case report

Myocardial injury due to acute carbon monoxide intoxication is often refractory to standard resuscitation methods. Levosimendan is a new inotropic agent that is used in the treatment of acute and chronic heart failure. We report a case of severe cardiopulmonary compromise after exposure to carbon monoxide in a 40-year-old woman who was monitored using transthoracic echocardiography and the arterial pulse contour analysis system (FloTrac) and successfully treated with levosimendan.

Accuracy and precision of calibrated arterial pulse contour analysis in patients with subarachnoid hemorrhage requiring high-dose vasopressor therapy: a prospective observational clinical trial

IntroductionCalibrated arterial pulse contour analysis has become an established method for the continuous monitoring of cardiac output (PCCO). However, data on its validity in hemodynamically instable patients beyond the setting of cardiac surgery are scarce. We performed the present study to assess the validity and precision of PCCO-measurements using the PiCCO™-device compared to transpulmonary thermodilution derived cardiac output (TPCO) as the reference technique in neurosurgical patients requiring high-dose vasopressor-therapy.MethodsA total of 20 patients (16 females and 4 males) were included in this prospective observational clinical trial. All of them suffered from subarachnoid hemorrhage (Hunt&Hess grade I-V) due to rupture of a cerebral arterial aneurysm and underwent high-dose vasopressor therapy for the prevention/treatment of delayed cerebral ischemia (DCI). Simultaneous CO measurements by bolus TPCO and PCCO were obtained at baseline as well as 2 h, 6 h, 12 h, 24 h, 48 h and 72 h after inclusion.ResultsPCCO- and TPCO-measurements were obtained at baseline as well as 2 h, 6 h, 12 h, 24 h, 48 h and 72 h after inclusion. Patients received vasoactive support with (mean ± standard deviation, SD) 0.57 ± 0.49 μg · kg-1 · min-1 norepinephrine resulting in a mean arterial pressure of 103 ± 13 mmHg and a systemic vascular resistance of 943 ± 248 dyn · s · cm-5. 136 CO-data pairs were analyzed. TPCO ranged from 5.2 to 14.3 l · min-1 (mean ± SD 8.5 ± 2.0 l · min-1) and PCCO ranged from 5.0 to 14.4 l · min-1 (mean ± SD 8.6 ± 2.0 l · min-1). Bias and limits of agreement (1.96 SD of the bias) were −0.03 ± 0.82 l · min-1 and 1.62 l · min-1, resulting in an overall percentage error of 18.8%. The precision of PCCO-measurements was 17.8%. Insufficient trending ability was indicated by concordance rates of 74% (exclusion zone of 15% (1.29 l · min-1)) and 67% (without exclusion zone), as well as by polar plot analysis.ConclusionsIn neurosurgical patients requiring extensive vasoactive support, CO values obtained by calibrated PCCO showed clinically and statistically acceptable agreement with TPCO-measurements, but the results from concordance and polar plot analysis indicate an unreliable trending ability.

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Introduction: Advancements in critical care have extended the use of point of care ultrasound (POCUS) exponentially in the hands of the experienced Intensivist. Current methods for measuring the cardiac output (CO) in the Intensive Care Unit (ICU) require invasive devices such as the Pulmonary Artery (PA) catheter or the arterial waveform pulse contour analysis (PCA). Each of these methods is an invasive technique with some inherent risks. This study was designed to test the accuracy and feasibility of carotid artery Doppler Flow Volume measurements and compare it to other existing invasive CO measurement modalities. Methods: A prospective observational cohort study conducted in an urban, academic tertiary care center. An IRB approval was obtained for the study. Patients were selected from the surgical or cardiothoracic ICU when invasive monitoring was already initiated via either a PA catheter or PCA. Patients with possible cerebral and carotid pathology were excluded. Physicians performing the Doppler study were experts in POCUS. Patients were placed in the semi-fowler position at 30 degrees with head rotated away from the site of measurement. Using the Sonosite edge with linear 38xi transducer 5-10MHz (Seattle, WA) images of the common carotid artery were obtained at the level of the thyroid gland. The Doppler flow volume was measured in different cycles (beats) and an average of 3 cycles was taken. Concurrent vital signs and measured cardiac output via invasive devices was recorded. Results: Patient cohort comprised 39 patients; 52% were females. Average age was 59+/- 13 years, and 66% were monitored by PCA device and 33% by PA. Intra class correlation (ICC) analysis was used to analyze the data. A perfect agreement was defined as ICC of 0.81–1.00 and substantial agreement was 0.61–0.80. The results demonstrated almost perfect correlation (0.8152) between measurements of CO by ultrasound versus invasive modalities. The ICC was 0.84 when compared to measurements by the PCA and 0.74 when compared to PA Catheter, showing substantial agreement between ultrasound and the invasive modalities. Conclusions: Using POCUS, Carotid Doppler flow volume can help estimate the CO in ICU patients with no carotid disease or apparent change in the cerebral circulation, and may limit the need for invasive monitoring for CO estimation.

Ability of the Third-Generation FloTrac/Vigileo Software to Track Changes in Cardiac Output in Cardiac Surgery Patients: A Polar Plot Approach

To evaluate the ability of the third-generation (3.01) of FloTrac/Vigileo monitor (Edwards Lifesciences, Irvine, CA) to follow variations in cardiac output (∆CO) using the new polar plot approach. Prospective interventional study. Single hospital university study. Twenty-five patients referred for cardiac surgery. CO was measured simultaneously by 3 to 5 bolus thermodilution (COtd measurements), using a pulmonary artery catheter and by arterial pulse contour analysis, using the FloTrac/Vigileo (COvi). Data were collected at eight time points: before incision, after sternotomy, before and after protamine sulfate infusion, at the start of sternal closure, at the end of surgery, on arrival to intensive care unit, and after a standardized volume expansion with 500 mL of hetastarch 6%. One-hundred thirty-five pairs of CO data were collected; the mean bias of all CO measurements corrected for repeated measures was 0.2 L/min with limits of agreements of -3.3 L/min and +2.9 L/min. The percentage error was 66.5%. The polar plot analysis included 71 significant ∆CO and showed a mean polar angle of -3.4 degrees with 95% polar percentage error equivalent limits of -61 to 55; 69% of analysed data points fell within the 30-degree limits and provided a correct polar concordance rate. Third-generation FloTrac/Vigileo software still lacks the accuracy to reliably detect changes in cardiac output (∆CO) in cardiac surgery. Improvements to FloTrac/Vigileo CO algorithm and software still are needed in this particular setting.

The effect of 6% hydroxyethyl starch 130/0.42 vs lactated Ringerʼs preload on the haemodynamic status of parturients undergoing spinal anaesthesia for elective caesarean delivery using arterial pulse contour analysis

Matsota, P.; Karakosta, A.; Pandazi, A.; Niokou, D.; Christodoulaki, K.; Kostopanagiotou, G. Author Information

Further Studies Should Evaluate Cardiac Output Measurement by the Nexfin Device

We read the article “Is Arterial Pulse Contour Analysis (PCA) Using Nexfin a New Option in the Noninvasive Measurement of Cardiac Output? —A Pilot Study” by Trinkmann et al1 with great interest. They aimed to evaluate the accuracy and precision of noninvasive cardiac output (CO) measurements using the new digital photoplethysmographic device (Nexfin, BMEYE, Amsterdam, The Netherlands) compared with cardiac magnetic resonance imaging (CMR). They reported that the noninvasive PCA allows the safe and economic measurement of CO, yet it still has major limitations.

Associations of Aortic Distensibility and Arterial Elasticity With Long-Term Visit-to-Visit Blood Pressure Variability: The Multi-Ethnic Study of Atherosclerosis (MESA)

Although higher visit-to-visit variability (VVV) of blood pressure (BP) is associated with increased cardiovascular disease risk, the physiological basis for VVV of BP is incompletely understood. We examined the associations of aortic distensibility (assessed by magnetic resonance imaging) and artery elasticity indices (determined by radial artery pulse contour analysis) with VVV of BP in 2,640 and 4,560 participants, respectively, from the Multi-Ethnic Study of Atherosclerosis. Arterial measures were obtained at exam 1. BP readings were taken at exam 1 and at 3 follow-up visits at 18-month intervals (exams 2, 3, and 4). VVV was defined as the SD about each participant's mean systolic BP (SBP) across visits. The mean SDs of SBP were inversely associated with aortic distensibility: 7.7, 9.9, 10.9, and 13.2mm Hg for quartiles 4, 3, 2, and 1 of aortic distensibility, respectively (P trend < 0.001). This association remained significant after adjustment for demographics, cardiovascular risk factors, mean SBP, and antihypertensive medication use (P trend < 0.01). In a fully adjusted model, lower quartiles of large artery and small artery elasticity (LAE and SAE) indices were also associated with higher mean SD of SBP (P trend = 0.02 for LAE; P trend < 0.001 for SAE). In this multiethnic cohort, functional alterations of central and peripheral arteries were associated with greater long-term VVV of SBP.

Stroke volume determination using transcardiopulmonary thermodilution and arterial pulse contour analysis in severe aortic valve disease

Transcardiopulmonary thermodilution (TPTD, SVTD) as well as calibrated (SVPC CAL) and uncalibrated (SVPC UNCAL) arterial pulse contour analysis (PC) are increasingly promoted as less-invasive technologies to measure stroke volume (SV) but their reliability in aortic valve disease was unknown. The objective of this prospective study was to investigate the validity of three less-invasive techniques to assess SV in conditions involving aortic stenosis (AS) and valvuloplasty-induced aortic insufficiency (AI) compared with transesophageal echocardiography. In 18 patients undergoing transcatheter aortic valve implantation, SVTD and SVPC CAL were determined using a central pressure signal via the brachial artery and SVPC UNCAL using a peripheral radial signal. In aortic valve dysfunction TPTD achieved adequate reproducibility (concordance correlation coefficient (CCC): AS 0.84; AI 0.82) and agreement (percentage error (PE): AS 26.3 %; AI 26.2 %) with the reference technique. In severe AS, SVPC CAL (PE 25.7 %; CCC 0.85) but not SVPC UNCAL (PE 50.4 %; CCC 0.38) was reliable. Neither calibrated nor uncalibrated PC (SVPC CAL: PE 51.5 %; CCC 0.49; SVPC UNCAL: PE 61.9 %; CCC 0.22) was valid in AI. Trending ability to hemodynamic changes, quantified by the ΔSV vector and the angle θ, was acceptable for each measurement modality. Transcardiopulmonary thermodilution is valid in aortic valve dysfunction. Calibration of PC substantially improves reliability in aortic valve disease. Calibrated PC is valid in severe AS. Valvuloplasty-induced AI seriously confounds PC measurements. In uncalibrated PC approaches, the relative SV trend is superior to single absolute values.

Fluid Therapy LiDCO Controlled Trial—Optimization of Volume Resuscitation of Extensively Burned Patients through Noninvasive Continuous Real-Time Hemodynamic Monitoring LiDCO

This pilot trial aims at gaining support for the optimization of acute burn resuscitation through noninvasive continuous real-time hemodynamic monitoring using arterial pulse contour analysis. A group of 21 burned patients meeting preliminary criteria (age range 18-75 years with second- third- degree burns and TBSA ≥10-75%) was randomized during 2010. A hemodynamic monitoring through lithium dilution cardiac output was used in 10 randomized patients (LiDCO group), whereas those without LiDCO monitoring were defined as the control group. The modified Brooke/Parkland formula as a starting resuscitative formula, balanced crystalloids as the initial solutions, urine output of 0.5 ml/kg/hr as a crucial value of adequate intravascular filling were used in both groups. Additionally, the volume and vasopressor/inotropic support were based on dynamic preload parameters in the LiDCO group in the case of circulatory instability and oligouria. Statistical analysis was done using t-tests. Within the first 24 hours postburn, a significantly lower consumption of crystalloids was registered in LiDCO group (P = .04). The fluid balance under LiDCO control in combination with hourly diuresis contributed to reducing the cumulative fluid balance approximately by 10% compared with fluid management based on standard monitoring parameters. The amount of applied solutions in the LiDCO group got closer to Brooke formula whereas the urine output was at the same level in both groups (0.8 ml/kg/hr). The new finding in this study is that when a fluid resuscitation is based on the arterial waveform analysis, the initial fluid volume provided was significantly lower than that delivered on the basis of physician-directed fluid resuscitation (by urine output and mean arterial pressure).

Perioperative goal-directed hemodynamic therapy based on radial arterial pulse pressure variation and continuous cardiac index trending reduces postoperative complications after major abdominal surgery: a multi-center, prospective, randomized study

IntroductionSeveral single-center studies and meta-analyses have shown that perioperative goal-directed therapy may significantly improve outcomes in general surgical patients. We hypothesized that using a treatment algorithm based on pulse pressure variation, cardiac index trending by radial artery pulse contour analysis, and mean arterial pressure in a study group (SG), would result in reduced complications, reduced length of hospital stay and quicker return of bowel movement postoperatively in abdominal surgical patients, when compared to a control group (CG).Methods160 patients undergoing elective major abdominal surgery were randomized to the SG (79 patients) or to the CG (81 patients). In the SG hemodynamic therapy was guided by pulse pressure variation, cardiac index trending and mean arterial pressure. In the CG hemodynamic therapy was performed at the discretion of the treating anesthesiologist. Outcome data were recorded up to 28 days postoperatively.ResultsThe total number of complications was significantly lower in the SG (72 vs. 52 complications, p = 0.038). In particular, infection complications were significantly reduced (SG: 13 vs. CG: 26 complications, p = 0.023). There were no significant differences between the two groups for return of bowel movement (SG: 3 vs. CG: 2 days postoperatively, p = 0.316), duration of post anesthesia care unit stay (SG: 180 vs. CG: 180 minutes, p = 0.516) or length of hospital stay (SG: 11 vs. CG: 10 days, p = 0.929).ConclusionsThis multi-center study demonstrates that hemodynamic goal-directed therapy using pulse pressure variation, cardiac index trending and mean arterial pressure as the key parameters leads to a decrease in postoperative complications in patients undergoing major abdominal surgery.Trial registrationClinicalTrial.gov, NCT01401283.

Nexfin noninvasive continuous hemodynamic monitoring: validation against continuous pulse contour and intermittent transpulmonary thermodilution derived cardiac output in critically ill patients.

Introduction. Nexfin (Bmeye, Amsterdam, Netherlands) is a noninvasive cardiac output (CO) monitor based on finger arterial pulse contour analysis. The aim of this study was to validate Nexfin CO (NexCO) against thermodilution (TDCO) and pulse contour CO (CCO) by PiCCO (Pulsion Medical Systems, Munich, Germany). Patients and Methods. In a mix of critically ill patients (n = 45), NexCO and CCO were measured continuously and recorded at 2-hour intervals during the 8-hour study period. TDCO was measured at 0–4–8 hrs. Results. NexCO showed a moderate to good (significant) correlation with TDCO (R 2 0.68, P < 0.001) and CCO (R 2 0.71, P < 0.001). Bland and Altman analysis comparing NexCO with TDCO revealed a bias (± limits of agreement, LA) of 0.4 ± 2.32 L/min (with 36% error) while analysis comparing NexCO with CCO showed a bias (±LA) of 0.2 ± 2.32 L/min (37% error). NexCO is able to follow changes in TDCO and CCO during the same time interval (level of concordance 89.3% and 81%). Finally, polar plot analysis showed that trending capabilities were acceptable when changes in NexCO (ΔNexCO) were compared to ΔTDCO and ΔCCO (resp., 89% and 88.9% of changes were within the level of 10% limits of agreement). Conclusion. we found a moderate to good correlation between CO measurements obtained with Nexfin and PiCCO.

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Introduction: A variety of less-invasive devices such as Edwards Lifescience’s FloTrac, which uses arterial pulse contour analysis, may be used to assess cardiac output. Hypothesis: We measured cardiac output using both the Edwards Vigilance Swan-Ganz Continuous Cardiac Output (CCO) and the Edwards FloTrac in a swine model of septic shock to determine the agreement between the measurements. Methods: Four domestic swine weighing 50-60kg were anesthetized, intubated, and ventilated. Arterial and venous lines were placed via femoral cutdown, a Swan-Ganz catheter was placed into the pulmonary artery, and placements were confirmed by waveform. The abdomen was opened via midline incision, the cecum was identified, 2-3 vessels were ligated to create an ischemic insult, and the cecum was perforated with a one cm incision using electrocautery. The peritoneum was inoculated with 1 g/kg of fresh feces. Swine were observed until the onset of hypotension (MAP<60) and were then given a fluid bolus and pressor agents to keep MAP 50-60 mmHg. Animals were observed until SvO2 reached 50-60%, at which time they were resuscitated using a modified Rivers protocol. Vital signs were recorded every 10 minutes. Animals were euthanized at the end of the experiment. Results: All animals developed septic shock. A total of 87 measurements were performed. Mean cardiac output for the Vigilance CCO system was 6.80 L/min (range 1.94-14.2 L/min). Mean cardiac output for the FloTrac system was 6.90 L/min (range 2.3-15.6 L/min). Bland-Altman analysis revealed mean difference of 6.84+/-2.27 L/min, with Limits of Agreement of (2.30, 11.4). Values were increasingly divergent when cardiac output was greater than 10 L/min. All animals survived to the end of the experiment. Conclusions: Cardiac output estimates from the FloTrac Vigileo system were significantly higher than those using the Edwards Vigilance CCO system in this swine model of septic shock. Funding: Emergency Medicine Departmental Pilot Grant

Evaluation of arterial waveform derived variables for an assessment of volume resuscitation in mechanically ventilated burn patients

ObjectiveThe purpose of this study was to assess the usefulness of stroke volume variations to monitor the early fluid resuscitation in mechanically ventilated burn ICU patients. Methods and resultsData of 29 burn patients (APACHE II – 9.8±3.6, SAPS II – 29±5, TBSA – 39.5±14) were prospectively included in this observational study. Hemodynamic parameters were determined using arterial pressure wave analysis for up to 36h after burn. Statistically significant changes in cardiac index (CI), systemic vascular resistance index (SVRI), stroke volume variation (SVV) were recorded during the observation period. There were significant correlations between CI and SVV (r=−0.454, p=0.03), SVV and SVRI (r=0.482, p=0.02) at 16h postburn; CI and SVV (r=−0.513, p=0.012), SVV and SVRI (r=0.480, p=0.02) at 24h postburn, CI and SVV at 36h postburn (r=−0.478, p=0.021). Significant changes in CI (1.9±1 vs. 3.4±0.9), p=0.02 and in SVV (24.9±3 vs. 14.6±2, p=0.01) were observed in patients with low cardiac output state after administration of 10ml/kg of Ringer lactate. ConclusionOur results suggest that measurement of stroke volume variations by arterial pulse contour analysis is valuable in monitoring volume administration and in predicting volume responsiveness during the early postburn period.