Comparison of the ability of two continuous cardiac output monitors to measure trends in cardiac output: estimated continuous cardiac output measured by modified pulse wave transit time and an arterial pulse contour-based cardiac output device

Estimated continuous cardiac output (esCCO), a noninvasive technique for continuously measuring cardiac output (CO), is based on modified pulse wave transit time, which in turn is determined by pulse oximetry and electrocardiography. However, its trending ability has never been evaluated in patients undergoing non-cardiac surgery. Therefore, this study examined esCCO’s ability to detect the exact changes in CO, compared with currently available arterial waveform analysis methods, in patients undergoing kidney transplantation. CO was measured using an esCCO system and arterial pressure-based CO (APCO), and compared with a corresponding intermittent bolus thermodilution CO (ICO) method. Percentage error and statistical methods, including concordance analysis and polar plot analysis, were used to analyze results from 15 adult patients. The difference in the CO values between esCCO and ICO was ?0.39 ± 1.15 L min^?1 (percentage error, 35.6 %). And corrected precision for repeated measures was 1.16 L min^?1 (percentage error for repeated measures, 36.0 %). A concordance analysis showed that the concordance rate was 93.1 %. The mean angular bias was ?1.8° and the radial limits of agreement were ±37.6°. The difference between the APCO and ICO CO values was 0.04 ± 1.37 L min^?1 (percentage error, 42.4 %). And corrected precision for repeated measures was 1.37 L min^?1 (percentage error for repeated measures, 42.5 %). The concordance rate was 89.7 %, with a mean angular bias of ?3.3° and radial limits of agreement of ±42.2°. This study demonstrated that the trending ability of the esCCO system is not clinically acceptable, as judged by polar plots analysis; however, its trending ability is clinically acceptable based on a concordance analysis, and is comparable with currently available arterial waveform analysis methods.     

Evaluation of a new continuous thermodilution cardiac output monitor in cardiac surgical patients: a prospective criterion standard study

OBJECTIVE: To evaluate the accuracy of a new continuous cardiac output monitor in critically ill patients. DESIGN: Criterion standard study. SETTING: Cardiac surgery intensive care unit in a university hospital. PATIENTS: Twenty cardiac surgical patients requiring intensive care treatment with pulmonary artery catheters after surgery. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Cardiac output was monitored continuously with a modified pulmonary artery catheter that has a heating filament on the outside of the catheter. Four modes of data processing with different response times ("Normal," "Fast," "FastFilter," and "Urgent" modes) used by the monitoring system. A total of 240 determinations of cardiac output were performed using conventional bolus thermodilution technique; these results were compared with those obtained using three of the four continuous measuring modes available ("Normal," "FastFilter," and "Urgent"). Cardiac output ranged from 3.47 to 15.77 L/min (bolus thermodilution). The mean (bias) +/- SD of differences (precision) for all measurements was 0.40+/-1.26 L/min in the Normal mode (cardiac output <10 L/min: 0.34+/-0.66 L/min), 0.53+/-1.27 L/min in the FastFilter-mode (cardiac output <10 L/min: 0.60+/-0.75 L/min), and 0.63+/-1.34 L/min in the Urgent mode (cardiac output <10 L/min: 0.57+/-0.82 L/min). CONCLUSIONS: Continuous cardiac output measurement using the thermodilution technique is reasonably accurate, reliable, and applicable in routine clinical practice. The values obtained using the Normal mode of the monitor agreed significantly better with the conventional thermodilution method than the results of the two other modes studied (FastFilter and Urgent). In addition, measurements in two patients with cardiac output values of >10 L/min did not agree with the results of the bolus thermodilution method.     

The use of a cardiac output monitor to guide the initial fluid resuscitation in a patient with burns

A case of initial resuscitation of a patient with severe burns is described. Such patients can have hypotension and reduced organ perfusion for a number of reasons, and can remain in the emergency department for many hours while awaiting transfer to specialist centres. The case provides a comparison between resuscitation using traditional burns formulae and a relatively new and simple-to-use cardiac output (CO) monitor--the Vigileo monitor (Edwards Lifesciences, Irvine, California, USA). The case demonstrates that relying on fluid regimes alone can lead to insufficient resuscitation. We suggest that using technologies such as those mentioned in this article, which have the potential to be used in the emergency department, could improve the initial resuscitation of patients with burns.     

1例人感染H7N9禽流感重症患者应用脉搏指示连续心排血量监测的护理

<正>人感染H7 N9禽流感是由H7 N9亚型禽流感病毒引起的急性呼吸道传染病,其重症患者病情发展迅速,可快速进展为急性呼吸窘迫综合征[1]。血管外肺水与急性呼吸窘迫综合征关系密切[2]。脉搏指示连续心排血量(pulse-induced continuous cardiac output,PICCO)监测已经被证明可以对高通透性肺水肿和高静水压性肺水肿进行诊断和鉴别,并可以对肺水肿的严重程度进行量化从而指     

Intraoperative validation of a new system for invasive continuous cardiac output measurement

Objective  Although bolus thermodilution technique for cardiac output (CO) measurement has widespread acceptance, new systems are currently available. We evaluated a continuous CO system (TruCCOMS, Aortech International Inc.) that operates on the thermal conservation principle and we compared it with the reference standard transit time flow measurement (TTFM). Materials and methods  Nine consecutive cardiac surgery patients were evaluated. After general anesthesia and intubation, a TruCCOMS catheter was percutaneously placed in the pulmonary artery (PA). After median sternotomy and pericardiotomy, a TTFM probe was placed around the main PA. Right ventricular (RV) CO measurements were recorded with both TruCCOMS and TTFM at different times: before cardiopulmonary bypass (CPB) (T0), during weaning from CPB (T1), and prior to sternal closure (T2). Data analysis included paired student t test, Pearson correlation test, and Bland–Altman plotting. Results  TruCCOMS CO values were significantly lower at T0 (TruCCOMS 4.0 ± 1.0 vs. TTFM 4.5 ± 1.0 L/min; P < 0.0001) and T1 (TruCCOMS 3.6 ± 0.5 vs. TTFM 4.2 ± 0.7 L/min; P < 0.0001), and comparable at T2 (TruCCOMS 4.5 ± 0.7 vs. TTFM 4.6 ± 0.8 L/min; P = 0.4). Pearson test showed a significant correlation between TruCCOMS and TTFM CO measurements (RT0 = 0.9, RT1 = 0.8, RT2 = 0.6; P < 0.0001). Bland–Altmann plotting showed a bias of −0.53 ± 0.43 L (−12%) at T0, −0.64 ± 0.43 L (−14.5%) at T1, and −0.1 ± 0.66 L (−0.8%) at T2. Conclusion  Although TruCCOMS may significantly underestimate CO, measurement trends correlate with TTFM. For this reason, a negative trend in RV output should trigger more specific diagnostic procedures.     

Validation of a new method based on ultrasound velocity dilution to measure cardiac output in paediatric patients

Purpose

To validate a novel method of ultrasound dilution (COstatus^®; Transonic Systems, Ithaca, NY) for measuring cardiac output in paediatric patients after biventricular repair of congenital heart disease.

Methods

Children undergoing biventricular repair of congenital heart disease were prospectively identified. Patients with significant intracardiac shunts were excluded. Postoperative cardiac output was measured by ultrasound dilution (COud) and concurrently calculated by the Fick equation (COrms) using measured oxygen consumption by respiratory mass spectrometry.

Results

Thirty-five patients were studied generating 66 individual data sets. Subjects had a median (interquartile range) age of 147 days (11, 216), weight of 4.98 kg (3.78, 6.90) and body surface area of 0.28 m² (0.22, 0.34). Of the patients, 66 % had peripheral arterial catheters and 34 % had femoral cannulation; peripheral arterial lines accounted for 6/8 of unsuccessful studies due to inability to generate sufficient flow. The site of the central venous cannula did not impact the feasibility of completing the study. A mean bias of 0.00 L/min [2 standard deviation (SD) ± 0.76 L/min] between COud and COrms was found with a percentage error of 97 %. When comparing cardiac index, bias increased to 0.13 L/min/m² (2SD ± 2.16 L/min/m²).

Conclusions

Cardiac output by ultrasound dilution showed low bias with wide limits of agreement when compared to measurement derived by the Fick equation. Although measurements through central and peripheral arterial lines were completed with minimal difficulties in the majority of patients, the application of COstatus^® in neonates with low body surface area may be limited.     

Capability of a new paediatric oesophageal Doppler monitor to detect changes in cardiac output during testing of external pacemakers after cardiac surgery

Background  

The Cardio QP™ oesophageal Doppler monitor measures the velocity time integral of the blood flow in the descending aorta. Based on system integrated normograms of the aortic cross-sectional area of a paediatric population, the cardiac output is calculated and displayed.     

Comparison of an advanced minimally invasive cardiac output monitoring with a continuous invasive cardiac output monitoring during lung transplantation

The aim of this study was to compare a continuous non-calibrated left heart cardiac index (CI) measurement by arterial waveform analysis (FloTrac^®/Vigileo^®) with a continuous calibrated right heart CI measurement by pulmonary artery thermodilution (CCOmbo-PAC^®/Vigilance II^®) for hemodynamic monitoring during lung transplantation. CI was measured simultaneously by both techniques in 13 consecutive lung transplants (n = 4 single-lung transplants, n = 9 sequential double-lung transplants) at distinct time points perioperatively. Linear regression analysis and Bland–Altman analysis with percentage error calculation were used for statistical comparison of CI measurements by both techniques. In this study the FloTrac^® system underestimated the CI in comparison with the continuous pulmonary arterial thermodilution (p < 0.000). For all measurement pairs we calculated a bias of ?0.55 l/min/m² with limits of agreement between ?2.31 and 1.21 l/min/m² and a percentage error of 55 %. The overall correlations before clamping a branch oft the pulmonary artery (percentage error 41 %) and during the clamping periods of a branch oft the pulmonary artery (percentage error 66 %) failed to reached the required percentage error of less than 30 %. We found good agreement of both CI measurements techniques only during the measurement point “15 min after starting the second one-lung ventilation period” (percentage error 30 %). No agreement was found during all other measurement points. This pilot study shows for the first time that the CI of the FloTrac^® system is not comparable with the continuous pulmonary-artery thermodilution during lung transplantation including the time periods without clamping a branch of the pulmonary artery. Arterial waveform and continuous pulmonary artery thermodilution are, therefore, not interchangeable during these complex operations.     

Evaluation of a new invasive continuous cardiac output monitoring system: the truCCOMS system

Objective To compare measurements of cardiac output using a new pulmonary artery catheter with those obtained using two " gold standard " methods: the periaortic transit time ultrasonic flow probe and the conventional pulmonary artery thermodilution.Design Prospective clinical trial.Setting Cardiac surgery operating room and surgical ICU in a university hospital.Material and methods In the operating room, a new pulmonary artery catheter (truCCOMS system) was inserted in eight patients. A periaortic flow probe was inserted in four of them. Measurements of cardiac output obtained with the truCCOMS catheter and with the flow probe were compared at different phases of the surgical procedure. In the intensive care unit, the cardiac output displayed by the truCCOMS monitor was compared with the value obtained after bolus injection performed subsequently.Results In the operating room (70 measurements), the coefficient of correlation between cardiac output measured by the flow probe and the truCCOMS system was r² = 0.79, the bias was +0.11 l/min with a precision of 0.47 l/min, and limits of agreement –0.83 to +1.05 l/min. In the intensive care unit (108 measurements), the coefficient of correlation between cardiac output measured by thermodilution and the truCCOMS system was r² = 0.56, the bias was –0.07 l/min, the precision was 0.66 l/min, and the limits of agreement were –1.39 to +1.25 l/min.Conclusion The truCCOMS system is a reliable method of continuous cardiac output measurement in cardiac surgery patients.     

Laser Doppler velocimetry as a monitor of cardiac output changes in dogs

Cutaneous blood flow may be measured utilizing a continuous, noninvasive technique, laser Doppler velocimetry (LDV). Monitoring of cutaneous blood flow by LDV might be a useful method to monitor cardiac output. To test this hypothesis, sequential measurements of cardiac output, LDV, and transcutaneous oxygen (PtcO2) were made on 10 anesthetized dogs during experimental shock. There was significant correlation between LDV and cardiac output, while PtcO2 reflected cardiac output only at low flow states. These results show that, in the animal model, cutaneous LDV is a sensitive and specific method for monitoring cardiac output changes.     

Planning for purchase and implementation of an automated hospital information system: a nursing perspective

Planning for purchase, implementation, and use of an automated hospital information system is critical to its success. The planning process involves assessing needs, evaluating alternatives, selecting a system, and implementation support. Although an evaluation of costs and benefits of alternative systems is useful in planning for and selecting a system, the assessment can be very complex, and the assumptions used in the analysis are critical. Most benefits of automated systems are the result of improved timeliness, accuracy, and access to information, and these are difficult to value in dollars.     

A new approach to the noninvasive measurement of cardiac output using an annular array Doppler technique--II. Practical implementation and results

An experimental Doppler flowmeter system has been developed which can noninvasively measure blood flow volume rate in a vessel. It is based on the attenuation compensated technique and does not require knowledge of the vessel size or beam-vessel angle. In vitro results have shown that the measurement of volume flow rate is independent of vessel angle to within +/- 4%, and independent of vessel diameter to within +/- 5%. Flow rate linearity is better than +/- 3%. A good comparison has been obtained, in vivo, of aortic diameters measured by an imaging system and with this flowmeter; the r value was 0.98. The noninvasive measurement of cardiac output using this flowmeter has been compared with conventional dilution techniques in 54 patients, with a resulting correlation coefficient of r = 0.96.     

Response time of the Opti-Q continuous cardiac output pulmonary artery catheter in the urgent mode to a step change in cardiac output

Objectives.This study was conducted to determine the response timeof the Opti-Q continuous cardiac output (CCO) device to a step change incardiac. Design.Prospective study. Setting.University hospitalanimal lab. Model.Female sheep. Interventions.In ten animals,cardiac output was altered suddenly by opening and closing a peripheralarteriovenous shunt to test the response time of the CCO system.Measurements and main results.Cardiac output was measured continuouslyby thermodilution and ultrasonic techniques while an arteriovenous shunt wasopened and closed. A total of 53 dynamic observations were made (5–6 peranimal). The mean response time of the continuous cardiac output device was86 seconds and was unaffected by the magnitude or direction of the change incardiac output. It was also unaffected by the animal's weight. CCOvalues were not statistically different from standard thermodilutionmeasurement (p= 0.895). Shunt flow ranged from 430 to 1730 ml/minand averaged 812 ml/min. The mean CCO with the shunt closed was 4.62 L/min.There was 1.5 to 2 minutes under or overshoot in cardiac output in 11% of themeasurements. Conclusions.Continuous cardiac output measurement wasas accurate as those made by standard bolus thermodilution. The averageresponse time to acute changes in cardiac output was approximately 1.5 minutesor ten times faster than previously reported systems. Response time isindependent of animal mass, shunt volume and the direction of cardiac outputperturbations.     

脉搏指示连续心排血量监测在感染性休克早期液体复苏中的应用

目的 探讨脉搏指示连续心排血量(PICCO)监测技术在感染性休克患者液体复苏中的应用价值.方法 2010年1月至2011年12月58例感染性休克患者根据治疗过程中是否应用PICCO监测技术将患者分为PICCO组(28例)和对照组(30例),对比分析两组患者治疗后早期目标导向治疗的液体复苏(EGDT)达标率、乳酸水平、中心静脉压(CVP)、氧合指数,72 h内液体入量、液体平衡、ICU内呼吸机应用时间、ICU住院时间、ICU内72 h后多脏器功能不全(MODS)发生率、28 d病死率.结果 (1)与对照组比较,PICCO组72 h内总的液体入量[(9565±1623) ml与(12 245 ±2253)ml,t=2.673,P=0.021]及正平衡[(3656±1904) ml与(5465±2765) ml,t=2.357,P=0.012]较对照组明显减少.(2)PICCO组72 h氧合指数较对照组明显增高(252.6±87.4与226.8±69.4,P＜0.05),呼吸机应用时间较对照组明显缩短[(134.7±42.8)h与(193.3±92.4)h,t=1.356,P=0.023].(3)两组在相同时间段乳酸水平、CVP值、6 hEGDT达标率、ICU住院时间、72 h后ICU内MODS发生率、28 d病死率方面比较差异均无统计学意义(P均＞0.05).结论 与CVP指导的常规液体复苏相比,PICCO监测技术可以更准确地对感染性休克患者进行容量管理,指导早期液体复苏.     

An alternative thermodilution method to measure cardiac output in a rat model of stagnant hypoxia

Rats are often used to study hemodynamics in animal research. We have established an alternative method to measure cardiac output in a conscious rat using a thermodilution technique via a left ventricular injection. The validity of this method was evaluated in conscious rats and compared with the results obtained using the radiolabeled microspheres (reference sample method). Using 20 male Sprague-Dawley rats, a baseline cardiac index was measured by thermodilution to determine the baseline cardiac index and to evaluate between animal variability. The baseline cardiac index was compared to the reference sample method with 6 rats. Following baseline measurements, an intra-atrial balloon was inflated in a stepwise manner to create 2 to 3 different cardiac outputs, and the cardiac index was computed. For each measurement, the cardiac index was first measured by thermodilution and immediately followed by the reference sample method. A total of 21 measurements were obtained, and the results were analyzed by a Bland-Altman plot and the correlation coefficient was calculated. Although the agreement between the two methods was poor, both methods had a good correlation (r2 = 0.59). With the thermodilution technique, we demonstrated a small coefficient of variation in each measurement, with a low intra-animal and inter-animal variability. As there is no gold standard method to measure cardiac output in rats, we believe that left ventricular thermodilution is a reliable method, and overcomes several technical difficulties such as heat loss, one of the significant limitations of the conventional thermodilution method (via right atrial injection). This new thermodilution technique (via the left ventricle) is therefore an attractive alternative method to measure cardiac output in rats.