Arterial Pressure Waveform Analysis Research Articles

Comparison between uncalibrated cardiac output using the femoral and radial arterial pressure waveform in critically ill patients

Cardiac output (CO) monitoring is often required to manage critically ill patients. Nominal values can be determined from analysis of arterial pressure waveforms. It is assumed that arterial waveforms from different arterial sites give similar CO values. The aim of this study was to compare the values of uncalibrated CO derived from simultaneous radial (COr) and femoral (COf) blood pressures.

Continuous Cardiac Output by using Arterial Pressure Waveform Analysis and Central Venous Oxygen Saturation during Cardiac Surgery - A case report -

TM ) in two cases of cardiac valve surgery, where placement of pulmonary artery catheter (PAC) was not applicable due to unfavorable cardiac structure (case 1) and was contraindicated due to an unstable cardiac conduction disorder and arrhythmia (case 2). In case 1, monitoring of APCO was started from the beginning of anesthesia induction and a ScvO2 monitoring central venous catheter was inserted just after anesthesia induction. APCO, ScvO2 and other hemodyanamic information such as arterial BP, CVP, and data obtained from transesophageal echocardiography (TEE) during the precardiopulmonary bypass (CPB) period were measured. APCO and ScvO2 during the post-CPB period showed a reliable correspondence with continuous cardiac output (CCO) and mixed venous O2 saturation (SvO2) as measured by PAC at the end of CPB. In case 2, APCO and ScvO2 were monitored instead of CCO and SvO2. The values of APCO showed a good correlation to intraoperative COs indirectly calculated by the velocity-time integral of the aortic outflow determined in the TEE examination. We experienced that monitoring APCO and ScvO2 is useful for anesthesia management in cardiac valve surgery and can be an alternative to CCO and SvO2 if the placement of PAC and the thermodilution method are not applicable. (Korean J Anesthesiol 2007; 53: 109～14)

Flow Trac™ cardiac output determination correlates with echocardiography

A new device may be used in intensive care to measure the cardiac output (CO) by arterial pulse pressure waveform analysis, but few studies have evaluated the reliability of this method and the correlation with other methods of CO determination. The aims of this study were to evaluate the CO obtained using the Flow Trac™ Vigileo™ and the correlation with CO obtained by transthoracic echocardiography (TTE).

Clinical evaluation of the FloTrac/Vigileo system and two established methods for continuous cardiac output monitoring in patients undergoing cardiac surgery

A new arterial pressure waveform analysis device, which does not need external calibration (FloTrac/Vigileo; Edwards Lifesciences, Irvine, CA, USA), became recently available for cardiac output (CO) measurement. However, only limited validation data for this technique are so far available [1,2].

Continuous cardiac output monitoring in humans by invasive and noninvasive peripheral blood pressure waveform analysis

We present an evaluation of a novel technique for continuous (i.e., automatic) monitoring of relative cardiac output (CO) changes by long time interval analysis of a peripheral arterial blood pressure (ABP) waveform in humans. We specifically tested the mathematical analysis technique based on existing invasive and noninvasive hemodynamic data sets. With the former data set, we compared the application of the technique to peripheral ABP waveforms obtained via radial artery catheterization with simultaneous thermodilution CO measurements in 15 intensive care unit patients in which CO was changing because of disease progression and therapy. With the latter data set, we compared the application of the technique to noninvasive peripheral ABP waveforms obtained via a finger-cuff photoplethysmography system with simultaneous Doppler ultrasound CO measurements made by an expert in 10 healthy subjects during pharmacological and postural interventions. We report an overall CO root-mean-squared normalized error of 15.3% with respect to the invasive hemodynamic data set and 15.1% with respect to the noninvasive hemodynamic data set. Moreover, the CO errors from the invasive and noninvasive hemodynamic data sets were only mildly correlated with mean ABP (rho = 0.41, 0.37) and even less correlated with CO (rho = -0.14, -0.17), heart rate (rho = 0.04, 0.19), total peripheral resistance (rho = 0.38, 0.10), CO changes (rho = -0.26, -0.20), and absolute CO changes (rho = 0.03, 0.38). With further development and successful prospective testing, the technique may potentially be employed for continuous hemodynamic monitoring in the acute setting such as critical care and emergency care.

Cardiac syndrome X: relevance of arterial pressure waveform analysis to patients with chest pain and normal coronary arteries

We report the case study of a 68-year-old female with cardiac syndrome X presenting with abnormal pressure waveforms and a hypertensive response to exercise with ST-segment depression. After amlodipine treatment, pressure waveform morphology was significantly improved, exercise testing was normal and symptoms had resolved. This case emphasizes the potential clinical value of arterial waveform analysis.

Predicting fluid responsiveness in patients undergoing cardiac surgery: functional haemodynamic parameters including the Respiratory Systolic Variation Test and static preload indicators

Prediction of the response of the left ventricular stroke volume to fluid administration remains an unsolved clinical problem. We compared the predictive performance of various haemodynamic parameters in the perioperative period in patients undergoing coronary artery bypass surgery. These parameters included static indicators of cardiac preload and functional parameters, derived from the arterial pressure waveform analysis. These included the systolic pressure variation (SPV) and its delta down component (dDown), pulse pressure variation (PPV), stroke volume variation (SVV), and a new parameter, termed the respiratory systolic variation test (RSVT), which is a measure of the slope of the lowest systolic pressure values during a standardized manoeuvre consisting of three successive incremental pressure-controlled breaths. Eighteen patients were included into this prospective observational study. Seventy volume loading steps (VLS), each consisting of 250 ml of colloid administration were performed before surgery and after the closure of the chest. The response to each VLS was considered as a positive (increase in stroke volume more than 15%) or non-response. Receiver operating characteristic curves were plotted for each parameter to evaluate its predictive value. All functional parameters predicted fluid responsiveness better than the intrathoracic blood volume and the left ventricular end-diastolic area. Parameters with the best predictive ability were the RSVT and PPV. Functional haemodynamic parameters are superior to static indicators of cardiac preload in predicting the response to fluid administration. The RSVT and PPV were the most accurate predictors of fluid responsiveness, although only the RSVT is independent of the settings of mechanical ventilation.

Comparison of arterial pressure waveform analysis with the lithium dilution technique to monitor cardiac output in anesthetized dogs

To assess agreement between arterial pressure waveform-derived cardiac output (PCO) and lithium dilution cardiac output (LiDCO) systems in measurements of various levels of cardiac output (CO) induced by changes in anesthetic depth and administration of inotropic drugs in dogs. 6 healthy dogs. Dogs were anesthetized on 2 occasions separated by at least 5 days. Inotropic drug administration (dopamine or dobutamine) was randomly assigned in a crossover manner. Following initial calibration of PCO measurements with a LiDCO measurement, 4 randomly assigned treatments were administered to vary CO; subsequently, concurrent pairs of PCO and LiDCO measurements were obtained. Treatments included a light plane of anesthesia, deep plane of anesthesia, continuous infusion of an inotropic drug (rate adjusted to achieve a mean arterial pressure of 65 to 80 mm Hg), and continuous infusion of an inotropic drug (7 microg/kg/min). Significant differences in PCO and LiDCO measurements were found during deep planes of anesthesia and with dopamine infusions but not during the light plane of anesthesia or with dobutamine infusions. The PCO system provided higher CO measurements than the LiDCO system during deep planes of anesthesia but lower CO measurements during dopamine infusions. The PCO system tracked changes in CO in a similar direction as the LiDCO system. The PCO system provided better agreement with LiDCO measurements over time when hemodynamic conditions were similar to those during initial calibration. Recalibration of the PCO system is recommended when hemodynamic conditions or pressure waveforms are altered appreciably.

Vascular stiffening and arterial compliance: Implications for systolic blood pressure

Hypertension in older persons is characterized by increased systolic blood pressure, and isolated systolic hypertension (ISH) is the most common type of hypertension in this population. It is thought that ISH results from age-associated vascular stiffening and reduced compliance that can be revealed and quantified by analysis of arterial pressure waveforms. Evaluation of pulse wave velocity and other related measures has shown that arterial stiffness increases with advancing age and other cardiovascular (CV) risk factors including hypertension, the metabolic syndrome, diabetes, obesity, hypercholesterolemia, and elevated C-reactive protein. Many of these relationships have been demonstrated in patients without clinical CV disease and are independent of patient age. Arterial stiffness is significantly and independently associated with both target organ damage and increased risk for CV morbidity and mortality. The mechanisms underlying age- and disease-related arterial stiffening are not fully understood. However, assessment of changes in gene expression associated with increased arterial stiffness and gene polymorphisms that increase the risk for vascular stiffening suggests that components of the renin-angiotensin system, matrix metalloproteinases, intracellular signaling, and extracellular matrix components may all be involved in this process. Interventions aimed at these targets may reduce vascular stiffness, lower systolic blood pressure, decrease the prevalence of ISH, and improve outcomes for patients (particularly older patients) with hypertension or other CV conditions.

Early recognition of low cardiac output after cardiac surgery by using the arterial pressure waveform analysis

ICU of Cardiothoracic Surgery, University of Siena, Dept. of Surgery and Bioengineering, Siena, Italy

PULSECO??? VALIDATION FOR CARDIAC OUTPUT MONITORING

Introduction: Recent technology for cardiac output (CO) measurement is inadequate for analysis of short-term effects of acute interventions such as biventricular pacing (BiVP). Arterial pressure (AP) waveform analysis has potential, but no controlled flow validations have been reported. Our initial observations in 10 patients during BiVP are promising, however in some cases mean AP changes are seen with no change in CO. Accordingly, we validated the PulseCO™ system (PC) in a controlled flow study. Methods: Using right-to-left heart bypass in an anesthetized pig (n=l), flow was varied from 3 to 1 L/min and then back to 3 in 0.5 L/min increments using 60 sec intervals (INT). CO was measured by ultrasonic aortic flow probe (FP) and PC. Interventions included: INT reduction to 30 and 10 sec and atrial pacing rate (HR) increase from 110 to 140 bpm. Beat-to-beat CO from PC and FP was compared by linear regression and Bland-Altman analysis. RESULTS: PC and FP correlated well initially (R2=0.86), with slope close to unity (y=l.06x+0.09). Bland-Altman analysis showed good agreement with bias=0.20 L/min (mean difference) and precision=±0.49 L/min (22 SD). However, as INT was reduced, the correlation and precision worsened (30 sec: R2=0.85, precision = ±0.52; 10 sec: R2=0.79, precision=±0.64). When HR increased, PC falsely indicated increased CO, while FP showed no change. Conclusion: PC is promising for monitoring CO during cardiac interventions. However, it requires 10 sec for stabilization and is confounded by changes in HR. Additional controlled flow experiments are needed to better define the capabilities of the PC system.

Preoperative partitioning of pulmonary vascular resistance correlates with early outcome after thromboendarterectomy for chronic thromboembolic pulmonary hypertension.

Pulmonary thromboendarterectomy (PTE) is the preferred treatment for chronic thromboembolic pulmonary hypertension (CTEPH), but persistent pulmonary hypertension after PTE, as a result of either inaccessible distal thrombotic material or coexistent intrinsic small-vessel disease, remains a major determinant of poor outcome. Conventional preoperative evaluation is unreliable in identifying patients at risk for persistent pulmonary hypertension or predicting postoperative hemodynamic outcome. We postulated that pulmonary arterial occlusion pressure waveform analysis, a technique that has been used for partitioning pulmonary vascular resistance, might identify CTEPH patients with significant distal, small-vessel disease. Twenty-six patients underwent preoperative right heart catheterization before PTE. Pulmonary artery occlusion waveform recordings were performed in triplicate. Postoperative hemodynamics after PTE were compared with preoperative partitioning of pulmonary vascular resistance derived from the occlusion data. Preoperative assessment of upstream resistance (Rup) correlated with both postoperative total pulmonary resistance index (R2=0.79, P<0.001) and postoperative mean pulmonary artery pressure (R2=0.75, P<0.001). All 4 postoperative deaths occurred in patients with a preoperative Rup <60%. Pulmonary arterial occlusion pressure waveform analysis may identify CTEPH patients at risk for persistent pulmonary hypertension and poor outcome after PTE. Patients with CTEPH and Rup value <60% appear to be at highest risk.

Hemodynamic and neurohumoral responses to head-up tilt in patients with chronic fatigue syndrome.

Data on the prevalence of orthostatic intolerance (OI) in patients with chronic fatigue syndrome (CFS) are limited and controversial. We tested the hypothesis that a majority of CFS patients exhibit OI during head-up tilt. Hemodynamic and neurohumoral responses to 40 minutes of head-up tilt were studied in 36 CFS patients and 36 healthy controls. Changes in stroke volume, cardiac output and peripheral vascular resistance were estimated from finger arterial pressure waveform analysis (Modelflow). Blood samples were drawn before and at the end of head-up tilt for measurement of plasma catecholamines. At baseline, supine heart rate was higher in CFS patients (CFS: 66.4 +/- 8.4 bpm; controls: 57.4 +/- 6.6 bpm; p < 0.001) as was the plasma epinephrine level (CFS: 0.11 +/- 0.07 nmol/l; controls: 0.08 +/- 0.07 nmol/l: p = 0.015). An abnormal blood pressure and/or heart rate response to head-up tilt was seen in 10 (27.8 %) CFS patients (6 presyncope, 2 postural tachycardia, 2 tachycardia and presyncope) and 6 (16.7 %, p = 0.26) controls (5 presyncope, 1 tachycardia, 2 tachycardia and presyncope). Head-up tilt-negative CFS patients showed a larger decrease in stroke volume during tilt (-46.9 +/- 10.6) than head-up tilt-negative controls (-40.3 +/- 13.6 %, p = 0.008). Plasma catecholamine responses to head-up tilt did not differ between these groups. Head-up tilt evokes postural tachycardia or (pre)syncope in a minority of CFS patients. The observations in head-up tilt-negative CFS patients of a higher heart rate at baseline together with a marked decrease in stroke volume in response to head-up tilt may point to deconditioning.

Left ventricular preload and function during graded haemorrhage and retranfusion in pigs: analysis of arterial pressure waveform and correlation with echocardiography

Arterial pressure waveform analysis is a new method for assessment of cardiac preload. Despite the close correlation of parameters derived by its use with the degree of blood loss, their relationship with more precise estimates of cardiac preload remains controversial. Systolic pressure variation (SPV), delta up (dUp), and delta down (dDown), which are the changes in the arterial blood pressure (BP) during mechanical ventilation, were measured during graded haemorrhage and retransfusion in seven pigs under light halothane anaesthesia, and compared with changes in cardiac filling pressures and left ventricular end-diastolic volume (LVEDV), measured by echocardiography. Significant changes in preload parameters and stroke volume (SV) but not in BP and heart rate occurred. SPV, dDown, and cardiac filling pressures correlated significantly with LVEDV. Following retransfusion, LVEDV returned to baseline values but the SV and left ventricular ejection fraction were significantly low. This deterioration in myocardial performance was associated with elevated dUp. During mechanical ventilation, dDown and the SPV may serve as minimally invasive indicators of preload. The retransfusion stage that follows significant blood loss may be associated with deterioration in LV function.

Pulmonary artery pulse pressure and wave reflection in chronic pulmonary thromboembolism and primary pulmonary hypertension

OBJECTIVESThe purpose of this time-domain study was to compare pulmonary artery (PA) pulse pressure and wave reflection in chronic pulmonary thromboembolism (CPTE) and primary pulmonary hypertension (PPH).BACKGROUNDPulmonary artery pressure waveform analysis provides a simple and accurate estimation of right ventricular afterload in the time-domain. Chronic pulmonary thromboembolism and PPH are both responsible for severe pulmonary hypertension. Chronic pulmonary thromboembolism and PPH predominantly involve proximal and distal arteries, respectively, and may lead to differences in PA pressure waveform.METHODSHigh-fidelity PA pressure was recorded in 14 patients (7 men/7 women, 46 ± 14 years) with CPTE (n = 7) and PPH (n = 7). We measured thermodilution cardiac output, mean PA pressure (MPAP), PA pulse pressure (PAPP = systolic − diastolic PAP) and normalized PAPP (nPAPP = PPAP/MPAP). Wave reflection was quantified by measuring Ti, that is, the time between pressure upstroke and the systolic inflection point (Pi), ΔP, that is, the systolic PAP minus Pi difference, and the augmentation index (ΔP/PPAP).RESULTSAt baseline, CPTE and PPH had similar cardiac index (2.4 ± 0.4 vs. 2.5 ± 0.5 l/min/m2), mean PAP (59 ± 9 vs. 59 ± 10 mm Hg), PPAP (57 ± 13 vs. 53 ± 13 mm Hg) and nPPAP (0.97 ± 0.16 vs. 0.89 ± 0.13). Chronic pulmonary thromboembolism had shorter Ti (90 ± 17 vs. 126 ± 16 ms, p < 0.01) and higher ΔP/PPAP (0.26 ± 0.01 vs. 0.09 ± 0.07, p < 0.01).CONCLUSIONSOur study indicated that: 1) CPTE and PPH with severe pulmonary hypertension had similar PA pulse pressure, and 2) wave reflection is elevated in both groups, and CPTE had increased and anticipated wave reflection as compared with PPH, thus suggesting differences in the pulsatile component of right ventricular afterload.

Room C, 10/16/2000 2: 00 PM - 4: 00 PM (PS) Hemodynamic Monitoring during Cardiac Surgery: Improved Arterial Pressure Waveform Analysis - The PulseCO System

<b>Room C, 10/16/2000 2: 00 PM - 4: 00 PM (PS) Hemodynamic Monitoring during Cardiac Surgery: Improved Arterial Pressure Waveform Analysis - The PulseCO System</b>

A System for Analysis of Arterial Blood Pressure Waveforms in Humans

Recent developments in arterial hemodynamics have indicated that the human arterial pressure waveform contains more information than is available from conventional sphygmomanometry. This information includes indices describing left ventricular systolic function and arterial properties. A cheap and reliable system was designed and implemented using readily available hardware for recording, analysis, and storage of arterial pressure waveforms. The system embodies an online technique for synthesizing ascending aortic pressure waveform from recordings made at different peripheral sites of the human arterial system. Eighteen indices are then derived from arterial pressure waveforms. This system can be used in an outpatient clinic for assisting in current pharmacological management of cardiovascular disease. It can also be extended to the critical care area, where the extra information provided aid in assessing the patient's condition.

Arterial Pressure Waveform Analysis During Hypovolemia

Arterial Pressure Waveform Analysis During Hypovolemia

Arterial Pressure Waveform Analysis During Hypovolemia

In Response: We thank Dr. Perel for his comments on our study. He raises important issues concerning the effect of volume status on Delta up and the difficulty in applying analysis of systolic pressure variation during spontaneous ventilation. We, too, were surprised to find a statistically significant relationship between Delta up and volume status in mechanically ventilated humans. Our study provides no obvious clues as why this was so, but we do think that species differences cannot be dismissed. All the articles concerning Delta up cited by Dr. Perel were studies performed on dogs [1-4], including the study by Brower et al. [4]. It seems plausible that the lungs of our subjects remained in Zone III throughout the study, given that they remained supine and were never profoundly hypovolemic. Assuming our patients had a typical compliance under anesthesia of 85 mL/cm H2 O [5], static pressure should not have exceeded 8 mm Hg for a typical tidal volume of 900 mL. Extremely low pulmonary artery pressures would have been required to place much of these human lungs into Zone II. The other possible explanations mentioned for the correlation between Delta up and volume status appear unlikely. None of our subjects had any suggestion of cardiac dysfunction, and so we doubt that Delta up was exaggerated on that basis. Failure to achieve a true equilibration of systolic pressure by the end of the expiratory period would indeed shift some of the systolic pressure variation from Delta down to Delta up. Although we did not use a full 5 s of apnea, our records show an unchanging systolic pressure, usually for several beats, prior to the onset of the next inspiration. Regardless of the mechanism behind the correlation between Delta up and volume status, the magnitude of the change was much smaller than for Delta down, and therefore Delta down is clearly the better of the two indices for the assessment of volume status in humans. The remaining issue brought up by Dr. Perel concerned the definitions of Delta up and Delta down during spontaneous ventilation. The physiological mechanisms responsible for Delta up and Delta down are clearly different during mechanical versus spontaneous ventilation; however, we felt constrained by our interpretation of the definitions of Delta up and Delta down. We agree that the distinction between Delta up and Delta down is probably meaningless during spontaneous ventilation and that such compartmentalization of systolic pressure ventilation should be limited to mechanical ventilation. Perhaps it was fortuitous that we could not adequately divide systolic pressure variation into a Delta up and a Delta down during spontaneous ventilation. In summary, we suspect, but cannot prove, that the relationship we observed between Delta up and intravascular volume status was due to differences in the anatomy between dogs and humans, with Zone III dominating the lungs of humans but not dogs. G. Alec Rooke, MD, PhD Howard A. Schwid, MD Department of Anesthesiology University of Washington School of Medicine Seattle, WA 98195

Arterial Pressure Waveform Analysis During Hypovolemia

Arterial Pressure Waveform Analysis During Hypovolemia