经肺热稀释法与肺动脉热稀释法测定猪心排血量的一致性

目的 评价经肺热稀释法与肺动脉热稀释法测定猪心排血量(CO)的一致性.方法对13只未成年猪,麻醉诱导后气管插管,机械通气,通过设定的方法依次进行血液动力学干预,于每次干预前及干预过程中血液动力学稳定至少10 min时,同时采用经肺热稀释法和肺动脉热稀释法测定CO(COTP,COPA).采用Bland-Altman法进行一致性分析,设定两种测定方法可以互换的界限为COTP 的相对误差<20%.结果 共收集205对CO数据,COTP范围为1.4～7.06 L/min,COPA范围为1.25～6.55 L/min,COTP值比COPA值高约2%;COTP的偏离度为0.07 L/min,95%可信区间(CI)为0.03～0.11 L/min;一致性范围为-0.46～0.60 L/min,其下限的95%CI为-0.53～-0.40 L/min,其上限的95%CI为0.54～0.66 L/min;COTP的相对误差为15.3%.结论 经肺热稀释法和肺动脉热稀释法测定猪CO具有良好的一致性.     

Measurement of cardiac output by transpulmonary arterial thermodilution using a long radial artery catheter. A comparison with intermittent pulmonary artery thermodilution

Cardiac output can be measured accurately by transpulmonary arterial thermodilution using the PiCCO (Pulsion Medical Systems, Munich, Germany) system with a femoral artery catheter. We have investigated the accuracy of a new 50 cm 4 French gauge radial artery catheter and the ability to use the system with a shorter radial catheter. We studied 18 patients who had undergone coronary artery surgery and made three simultaneous measurements of cardiac output by arterial thermodilution and with a pulmonary artery catheter. The radial catheter was withdrawn in 5 cm increments and the measurements were repeated. We found close agreement between arterial thermodilution and pulmonary artery thermodilution with a mean (SD) bias of 0.38 (0.77) l x min(-1). Arterial thermodilution became unreliable once the catheter had been withdrawn by more than 5 cm. We conclude that cardiac output measurement with arterial thermodilution with a radial catheter is interchangeable with that derived from a pulmonary artery catheter, and that a centrally sited arterial catheter is required for accurate determination of cardiac output by transpulmonary arterial thermodilution.     

Pulmonary artery blood temperature and the measurement of cardiac output by thermodilution

Thermodilution cardiac output measurement assumes that the temperature within the pulmonary artery is stable during the measurement period. This may not be achieved in clinical practice because of temperature changes that are not solely produced by the thermal indicator. Such temperature changes constitute thermal noise. Thermal noise and how it may interfere with measurement is discussed with reference to both the injectate and the thermal filament methods of thermodilution cardiac output measurement.     

Comparison of electrical velocimetry and transpulmonary thermodilution for measuring cardiac output in piglets

BACKGROUND: Monitoring of cardiovascular function is essential during major pediatric and pediatric cardiac surgery. Invasive monitoring of cardiac output (CO) and oxygen delivery is expensive and sometimes associated with adverse events. Therefore, we investigated the accuracy of a new noninvasive CO monitoring device using electrical velocimetry (EV) in comparison with the more invasive transpulmonary thermodilution (TPTD) method. METHODS: In five fasted, anesthetized and mechanically ventilated piglets, CO was measured simultaneously using EV and TPTD under normal conditions, volume loading, inotropic support and exsanguination. RESULTS: In five piglets, 169 measurements could be performed. The correlations between EV-CO and TPTD-CO were significant for absolute values (P < 0.0001, r = 0.82) and relative changes from baseline (P < 0.0001, r = 0.93). The receiver operating characteristic (ROC) curve analysis of the relative changes of the EV-CO values in relation to the first EV-CO measurement showed a sensitivity of 91% and specificity of 94% (AUC 0.974, 95% CI 0.96-0.99). Changes in TPTD-CO greater than 15% lead to a change of EV-CO in the same direction in 93%. Bland-Altman analysis showed a mean difference between the two methods of -0.63 l x min(-1) with an sd of 0.64 l x min(-1). The lower and upper limits of agreement were -1.88 and 0.62 l x min(-1), percentage limit of agreement was +/-82.8%. CONCLUSIONS: The results show that EV is a safe, simple, noninvasive and cost-effective method for continuous trend monitoring of CO in piglets. The agreement of the EV-CO with TPTD-CO is not good enough to replace the standard method in our animal model. A correction factor for body habitus in piglets may be beneficial.     

Continuous cardiac output during off-pump coronary artery bypass surgery: pulse-contour analyses vs pulmonary artery thermodilution

Background: No gold standard method exists for monitoring continuous cardiacoutput (CO). In this study, the agreement between the two mostfrequently used methods, PiCCO pulse-contour analysis (PCCO)and STAT pulmonary artery thermodilution (STAT-CO), was assessedduring multiple-vessel off-pump coronary artery bypass (OPCAB)surgery. Methods: Thirty patients were enrolled in the study. Two time periodswere defined during surgery; Period 1 included positioning ofthe heart and stabilizer device and Period 2 included the coronaryocclusion. Measurements were obtained every minute during bothperiods. The agreement for the continuous CO and the changein CO (CO) was estimated using the Bland–Altman method. Results: Significant changes in mean arterial pressure (MAP), centralvenous saturation, PCCO and STAT-CO were seen only during Period1. MAP correlated only with changes in PCCO, (P < 0.001,r = 0.60). The mean difference (2SD) between PCCO and STAT-COranged from – 0.29 (1.82) to – 0.71 (2.57) litremin^–1, and the percentage error varied from 32 to 50%.For the CO measurements, the limits of agreements did not differbetween Period 1 and Period 2. In contrast, for the CO measurements,the limits of agreements were wider in Period 1 than in themore haemodynamically stable Period 2. Conclusions: PCCO and STAT-CO show large discrepancies in CO during OPCABsurgery. Clinically acceptable agreement was seen only for trendsin CO during haemodynamically stable periods.     

A comparison of CardioQ and thermodilution cardiac output during off-pump coronary artery surgery

OBJECTIVE: To compare CardioQ esophageal Doppler cardiac output and thermodilution cardiac output during off-pump coronary artery bypass surgery. DESIGN: Prospective clinical study. SETTING: University-affiliated teaching hospital PARTICIPANTS: Adult patients (n = 20) undergoing elective coronary artery bypass surgery without cardiopulmonary bypass. MEASUREMENTS AND MAIN RESULTS: Three hundred thirty-one comparisons of simultaneous CardioQ and thermodilution cardiac outputs were made. The Pearson correlation coefficient for the pooled data was 0.62. Using a Bland-Altman approach, the overall bias was -0.56 L/min with a precision of 0.64 L/min. The 95% limits of agreement (bias +/- 2 SD) were -0.56 +/- 1.28 L/min. For individual patients, the bias ranged from -1.35 L/min to 0.27 L/min and the precision from 0.24 L/min to 0.74 L/min. CONCLUSION: Because of the wide limits of agreement and the large interpatient differences in both bias and precision, the CardioQ esophageal Doppler cardiac output cannot currently be recommended as an alternative to thermodilution cardiac output during off-pump coronary artery bypass surgery.     

Pulsed dye densitometry with two different sensor types for cardiac output measurement after cardiac surgery: a comparison with the thermodilution technique

BACKGROUND: Assessment of cardiac output (CO) by the indocyanine green (ICG) dye dilution technique (IDD) with transcutaneous signal detection may be a less invasive alternative to the pulmonary artery catheter (PAC). The aim of this study was to determine the accuracy and reliability of the DDG2001 analyzer (Nihon Kohden Corp, Tokyo, Japan) using a finger (IDDf) and a nose (IDDn) sensor as compared with the thermodilution technique by PAC. METHODS: In 31 consecutive patients after routine cardiac surgery, CO measurements were performed by IDD compared with the thermodilution technique following postoperative haemodynamic stabilization in the intensive care unit. Repeated measurements were made at 30-min intervals. CO was determined by iced water bolus (IWB: mean of three repeated injections) and IDDf or IDDn, respectively (mean of three repeated ICG injections). RESULTS: Thirty-three per cent of all measurements for IDDf and 9% for IDDn failed due to a missing signal detection. Mean bias for IDDf to IWB was -0.5 l min(-1).m(-2) (limits of agreement: -1.8/0.8 l min(-1).m(-2)) and for IDDn to IWB was -0.1 l min(-1).m(-2) (limits of agreement: -1.6/1.5 l min(-1).m(-2)). Correlation between IDDf and IWB (r = 0.2) was found to be inferior to the correlation between IDDn and IWB (r = 0.5). CONCLUSION: The IDD showed a systematic bias compared with the IWB and its performance was limited due to signal detection failure. Therefore, the DDG2001 analyzer cannot be recommended as a substitute for the PAC in routine monitoring of cardiac output after cardiac surgery.     

Cardiac output--pulse contour analysis vs. pulmonary artery thermodilution

BACKGROUND: The aims of this study were to determine the agreement between pulmonary artery thermodilution (PA-TD), transpulmonary thermodilution (TP-TD) and the pulse contour method, and to test the ability of the pulse contour method to track changes in cardiac output. METHODS: Cardiac output was determined twice before cardiac surgery with both PA-TD and TP-TD. The precision (two standard deviations of the difference between repeated measurements) and agreement of the two methods were calculated. Post-operatively, cardiac output was determined with the PA-TD and pulse contour methods, and the bias and limits of agreement were again calculated. Finally, in patients with heart rates below 60 beats/min or a cardiac index of less than 2.5 l/min/m2, atrial pacing was started and the haemodynamic consequences were monitored with the PA-TD and pulse contour methods. RESULTS: Twenty-five patients were included. The precisions of PA-TD and TP-TD were 0.41 l/min [95% confidence interval (CI), +/- 0.07] and 0.48 l/min (95% CI, +/- 0.08), respectively. The bias and limits of agreement between PA-TD and TP-TD were - 0.46 l/min (95% CI, +/- 0.11) and +/- 1.10 l/min (95% CI, +/- 0.19), respectively. Post-operatively, the bias and limits of agreement between the PA-TD and pulse contour methods were 0.07 l/min and +/- 2.20 l/min, respectively. The changes in cardiac output with atrial pacing were in the same direction and of the same magnitude in 15 of the 16 patients. CONCLUSION: The precision of cardiac output measurements with PA-TD and TP-TD was very similar. The transpulmonary method, however, overestimated the cardiac output by 0.46 l/min. Post-operatively, cardiac output measurements with the PA-TD and pulse contour methods did not agree, but the pulse contour method reliably tracked pacing-induced changes in cardiac output.     

Transoesophageal echocardiography is unreliable for cardiac output assessment after cardiac surgery compared with thermodilution

This randomised, single-blind, double-control study compared and established prospectively the best transoesophageal echocardiography methods for determining cardiac output in patients after cardiac surgery. Thirty patients undergoing coronary artery bypass grafting were included. Measurements were taken postoperatively, after stabilisation in the intensive care unit. Cardiac output was determined by transoesophageal echocardiography in randomised order through the aortic, mitral, and pulmonary valves, right and left ventricular outflow tracts, transgastric surface areas of the left ventricle and left ventricle two-dimensional volumes (Simpson's rules). 'Eyeball guessing' was done off-line. The best results were transaortic measurements using the triangular shape assumption of valve opening, but some values deviated considerably, and none of these approaches reached the limit of agreement set at 30% when compared to thermodilution. Eyeball guessing was comparable to the best transoesophageal echocardiography measurements. We conclude that transoesophageal echocardiography is an unreliable tool for determination of cardiac output in intensive care after cardiac surgery.     

Measurement of cardiac output: a comparison between transpulmonary thermodilution and uncalibrated pulse contour analysis

Background: Recently, continuous monitoring of cardiac output (CO) basedon pulse contour analysis (Vigileo^®) has been introducedinto practice. In this clinical study, we evaluated the accuracyof this system by comparing it with the transpulmonary thermodilutiontechnique (TPID) in septic patients. Methods: We studied 24 mechanically ventilated patients with septic shock(16 male, 8 female, age 26–77 yr) receiving treatmentwith norepinephrine who for clinical indication underwent haemodynamicmonitoring by the transpulmonary thermodilution technique usinga PiCCO^®plus system (Pulsion Medical Systems, Munich, Germany).In parallel, arterial pulse contour was applied using the femoralarterial pressure curve (FloTrac^® pressure sensor, Vigileo^®monitor, Edwards Lifesciences, Irvine, USA). After baselinemeasurement, mean arterial pressure was elevated by increasingnorepinephrine dosage, and CO was measured again before meanarterial pressure was reduced back to baseline levels. Fluidstatus and ventilator settings remained unchanged throughout.At each time point, CO by transpulmonary thermodilution wascalculated from three central venous bolus injections of 15ml of saline (<8°C). Linear regression and the Bland–Altmanmethod were used for statistical analysis. Results: Overall, CO was 6.7 (SD 1.8) (3.2–10.1) litre min^–1for CO(TPID) and 6.2 (2.4) (3.0–17.6) litre min^–1for CO(Vigileo^®). Linear regression revealed: CO(Vigileo^®)= 1.54 + 0.72 x CO(TPID) litre min^–1, r² = 0.26 (P <0.0001). Mean bias between techniques [CO(TPID)–CO(Vigileo^®)]was 0.5 litre min^–1 (SD 2.3 litre min^–1). Correlationcoefficients at the three time points were not significantlydifferent from each other. Conclusions: Pulse contour analysis-derived CO (Vigileo^® system) underestimatesCO(TPID) and is not as reliable as transpulmonary thermodilutionin septic patients.     

肝移植术中连续温度稀释法监测心排血量的准确性

目的 评价肝移植术中连续温度稀释法监测心排血量(CO)的准确性.方法 13例非静脉-静脉转流原位肝移植术病人,术中采用Abbott Opti-Q CCO/SvO2连续心排血量仪监测CO(CCO);并于麻醉诱导后20、40、60、90、120 min、下腔静脉阻断5、15、25、35、45 min和下腔静脉开放5、15、25、60、90、120min时采用单次温度稀释法监测CO(BCO),连续测定3次,取其平均值;于BCO测定前后取两次CCO的平均值为该时点的CCO.计算各时点CCO与BCO间的相关系数,采用Bland-Altman法进行一致性检验.结果 共收集196对CO数据,CCO范围为1.9～17.9 L/min,BCO范围为2.1～18.3L/min.与其余时点比较.下腔静脉阻断5 min和下腔静脉开放5 min时CCO和BCO间的相关系数较低,偏离度较大,CCO监测存在明显的响应时间延迟现象;其他时点CCO和BCO间的偏离度为-0.18L/min,95%可信区间为-0.32～-0.03 L/min,一致性界限为-2.09～1.73 L/min,其下限的95%可信区间为-2.34～-1.84 L/min,其上限的95%可信区间为1.48～1.99 L/min.CCO和BCO的重复系数分别为0.36和0.86 L/min.CCO与BCO的平均值与CCO的差值为(0.09±0.49)L/min,CCO的相对误差为4.6%±1.7%.结论 肝移植术中血液动力学改变显著时,CCO存在明显的响应时间延迟现象;而在血液动力学相对稳定时,CCO和BCO之间缺乏良好的一致性,但CCO监测在临床上是可接受的.     

Pulse contour analysis versus thermodilution in cardiac surgery patients

BACKGROUND: Previous studies have demonstrated that there is a lack of agreement between intermittent cold bolus thermodilution (ICO) and a semicontinuous method with dilution of heat (CCO) in cardiac surgical patients following hypothermic extracorporeal circulation (HCPB). Therefore, the aim of the present study was to compare both ICO and CCO with continuous pulse contour analysis (PCCO): a method based on a fundamentally different principle of determining cardiac output (CO). METHODS: A prospective criterion standard study of 25 cardiac surgery patients undergoing HCPB. Cardiac output was determined using the three methods (ICO, CCO, and PCCO) before and after HCPB up to 12 h after arrival on the ICU. Bias and precision were evaluated. RESULTS: A total of 380 triple determinations of CO could be analyzed. During the entire study period bias PCCO-ICO was -0.14 l*/min (precision 1.16 l*/min) and bias CCO-ICO was -0.40 l*/min (precision 1.25 l*/min). Up to 45 min after bypass PCCO agreed with ICO (bias -0.21 l*/min, precision 1.37 l*/min), while bias CCO-ICO was -1.30 l*/min (precision 1.45 l*/min). CONCLUSION: The agreement between PCCO and ICO in contrast to CCO in the first 45 min after HCPB indicates that CCO underestimates CO during this period.     

A new closed-system using partially frozen injectate for thermodilution cardiac output determinations

The FI (partially frozen injectate) system, a new closed-system devised by the authors for thermodilution cardiac output determinations, has two major features: 1) it needs no ice-filled receptacle to keep injectate cold because it uses partially frozen injectate, and 2) it can go without monitoring the injectate temperatures during the whole process of cardiac output determinations. The author evaluated the accuracy and reproducibility of cardiac output determinations with the FI system in 10 critically ill patients, as compared with another closed-system (which is commercially available) and the standard open method. The injectate temperatures in the FI system were also measured in vitro. The mean injectate temperature in the FI system was 0.71 ± 0.26°C and 80% of the injectate temperatures were lower than 1.0°C. Even when no monitoring of injectate temperatures was made, the predicated error in the calculated cardiac output resulted as low as 2% with the FI system. The mean cardiac output values were not statistically different between the FI system and the other two systems.(Maruta H, Usuda Y, Okutsu Y et al.: A new closed-system using partially frozen injectate for thermodilution cardiac output determinations. J Anesth 3: 35–39, 1989)     

Precision of bolus thermodilution cardiac output measurements in patients with atrial fibrillation

Background: The precision of bolus thermodilution cardiac output measurements in patients with atrial fibrillation (AF) has not previously been determined. A priori we suspected that the precision would be lower in patients with AF than in patients with sinus rhythm (SR). Consequently, we also determined if the precision could be improved by injecting the thermal indicator into the right ventricle instead of the right atrium. Methods: Cardiac output was determined as the average result of four injections of 10 ml of iced saline. Replicate measurements were performed with thermal indicator injections into the right atrium and ventricle. The coefficients of variation and the precisions were calculated. Results: In the 25 patients with AF, mean cardiac output was 3.96 l min^?1 (range 2.4–7.4), the coefficient of variation 0.073 (95% CI ± 0.011), and the precision 0.38 l min^?1 (95% CI ± 0.14) with injection into the right atrium. In the 25 patients with SR, mean cardiac output was 4.73 l min^?1 (range 2.4–7.3), the coefficient of variation 0.047(95% CI ± 0.006), and the precision 0.38 l min^?1 (95% CI ± 0.14). In both groups, an agreement analysis demonstrated that the injection of indicator into the right ventricle resulted in a significantly higher cardiac output [AF+0.25 (95% CI ± 0.15) l min^?1, SR+0.29 ( ± 0.20) l min^?1]. Conclusion: The coefficient of variation for cardiac output determinations is 55% higher in patients with AF. Two measurements, separated by time or intervention, must differ by 15% in AF patients and 9% in SR patients before one can be 95% confident that a real change has taken place.     

Low cardiac output syndrome in children

Clinicians caring for critically ill children will commonly encounter low cardiac output states, especially after cardiac surgery. Anticipation and prevention can go some way to reducing morbidity and mortality. This article outlines the causes and assessment of this syndrome. Management strategies are discussed aimed at improving cardiac output by optimisation of left- and right-ventricle preload and afterload. Pharmacological strategies utilising well-established as well as new agents are outlined. Non-pharmacological strategies are presented, as well as methods of reducing the adverse effects of low cardiac output on the child.     

部分二氧化碳重复吸入法与温度稀释法测定心排血量的相关性研究

目的　研究部分二氧化碳重复吸入法和温度稀释法监测心排血量 (CO)的相关性。方法　重症监护病房 (ICU) 1 5例危重患者 ,在呼吸机辅助控制通气条件下 ,采用美国无创心肺功能监测仪 (NICO)用部分二氧化碳重复吸入法 (RB)连续监测无创心排血量 (RBco) ,并同时采用温度稀释法测定心排血量 (TDco) ,两种方法所测CO值进行自体配对相关性研究。结果　配对t检验示两种方法测定的CO值无显著性差异 (P >0 0 5 ) ,相关回归分析示相关系数为 0 90 ,回归方程为RBco =0 81TDco +1 2 5 ,偏离为 0 2 0 ,精确度为 0 78。结论　部分二氧化碳重复吸入是一种简便、快捷、连续、无创的CO测定方法 ,该法与温度稀释法有良好的相关性 ;在无条件行肺动脉漂浮导管插入有创心功能监测的医院 ,这种无创CO监测是一种安全可靠的选择     

A comparison of cardiac output derived from the arterial pressure wave against thermodilution in cardiac surgery patients

In three clinical centres, we compared a new method for measuringcardiac output with conventional thermodilution. The new methodcomputes beat-to-beat cardiac output from radial artery pressureby simulating a three-element model of aortic input impedance,and includes non-linear aortic mechanical properties and a self-adaptingsystemic vascular resistance. We compared cardiac output bycontinuous model simulation (MF) with thermodilution cardiacoutput (TD) in 54 patients (18 female, 36 male) undergoing coronaryartery bypass surgery. We made three or four conventional thermodilutionestimates spread equally over the ventilatory cycle. In 490series of measurements, thermodilution cardiac output rangedfrom 2.1 to 9.3, mean 5.0 litre min^–1. MF differed +0.32(1.0) litre min^–1 on average with limits of agreementof –1.68 and +2.32 litre min^–1. Differences decreasedwhen the first series of measurements in a patient was usedto calibrate the model. In 436 remaining series, the mean differencebecame –0.13 (0.47) litre min^–1 with limits of agreementof –1.05 and +0.79 litre min^–1. When consecutivemeasurements were made, the change was greater than 0.5 litremin^–1, on 204 occasions. The direction of change was thesame with both methods in 199. The difference between the methodsremained near zero during surgery suggesting that a single calibrationper patient was adequate. Aortic model simulation with radialartery pressure as input reliably monitors changes in cardiacoutput in cardiac surgery patients. Before calibration, themodel cannot replace thermodilution, but after calibration themodel method can quantitatively replace further thermodilutionestimates. Br J Anaesth 2001; 87: 212–22     

Level of agreement between cardiac output measurements using Nexfin® and thermodilution in morbidly obese patients undergoing laparoscopic surgery

Morbidly obese patients are at increased risk of intra‐operative haemodynamic instability, which may necessitate intensive monitoring. Non‐invasive monitoring is increasingly used to measure cardiac output; however, it is unknown whether the weight‐based algorithm utilised in these devices is applicable to patients with morbid obesity. We compared the level of agreement and trending ability of non‐invasive cardiac output measurements (Nexfin^®) with the gold‐standard thermodilution technique in 30 morbidly obese patients undergoing laparoscopic surgery. Bland–Altman analysis revealed a mean (SD) bias of 0.60 (1.62) l.min^?1 (limits of agreement ?2.67 to 3.86 l.min^?1) and the precision error was 46%. Polar plot analysis resulted in an angular bias of 2.61°, radial limits of agreement of ?60.08° to 49.82° and angular concordance rate was 77%. Both agreement and trending were outside the Critchley criteria for the comparison of cardiac output devices with a gold‐standard. Nexfin has an unacceptable level of agreement compared with thermodilution for cardiac output measurement in morbidly obese patients.     

Impedance cardiography in cardiac surgery patients: abnormal body weight gives unreliable cardiac output measurements

Background: To study the accuracy of cardiac output measurement by means of Electrical Impedance Cardiography (EIC) in post-cardiac surgery patients.
Methods: In a prospective study, we compared cardiac output measurements by means of thermodilution (COTD) with impedance cardiographic-derived values (CO^EIC) in 37 mechanically ventilated patients after cardiac surgery. Both methods were used simultaneously.
Results: CO^EIC values were weakly correlated with CO^TD in the total group when the equation of Sramek-Bernstein was employed to calculate CO^EIC (r=0.60, P < 0.001, mean difference and standard deviation: -0.06±1.25 l-min^-1). After exclusion of the 12 patients whose body weight differed >15% from their ideal body weight, no significant difference was found between the mean values (5.40±1.80 l-min^-1 (CO^EIC) vs 5.31±1.69 l-min^-1, n=25) while the correlation coefficient increased substantially (r=0.85, P < 0.001, mean difference and standard deviation: 0.09±0.96 l-min^-1).
Conclusions: The results of this study indicate that weight is a very important factor in unreliable measurement of CO by impedance cardiography in cardiac surgery patients. The calculation equation as proposed by Sramek and Bernstein is not accurate enough in patients with more than 15% of weight deviation. Therefore, the use of impedance cardiography in these patients is of limited value until an accurate correction factor has been developed.