Continuous cardiac output measured with a Swan-Ganz catheter reacts too slowly in animal experiments with sudden circulatory failure

Background : In many animal experiments, it is vital to detect sudden changes in cardiac output(CO). This porcine study compared CO that was measured with a SwanGanz pulmonary catheter with the gold standard(which was a transit-time flow probe around the pulmonary artery) during interventions that caused hemodynamic instability.Methods : In one series, 7 pigs were exposed to sudden changes in CO. In another series, 9 pigs experienced more prolonged changes in CO. All the pigs had a Swan-Ganz catheter placed into the pulmonary artery and a flow probe around the pulmonary artery. Adrenaline infusion and controlled hemorrhage were used to increase and decrease CO, respectively. The measurements of CO before and after each intervention were compared for correlation, agreement, and the time delay that it took each method to detect at least a 30% change in CO. A Bland– Altman test was used to identify correlations and agreements between the methods.Results : In the first series, there was a delay of 5– 7 min for the Swan Ganz catheter to register a 30% change in cardiac output, compared with the flow probe. However,during prolonged changes in CO in the second series, there was a good correlation between the 2 methods. Mixed venous oxygen saturation reacted faster to changes than did CO;both were measured via the Swan-Ganz catheter.Conclusions : In many animal studies, the use of Swan-Ganz catheters is suitable;however, in experiments with sudden hemodynamic instability, the flow probe is the most advantageous method for measuring CO.

Comparison of Cardiac Output and Hemodynamic Responses of Intubation among Different Videolaryngoscopies in Normotensive and Hypertensive Patients

Tracheal intubation with Macintosh laryngoscope（MAC） might result in severe cardiovascular complications. The results of conducted studies investigating the effects of videolaryngoscopies on hemodynamic response of tracheal intubation are conflicting. We know little about the effects of videolaryngoscopies on cardiac output changes during tracheal intubation. We compared cardiac output（COP） and hemodynamic responses in normal blood pressure（n=60） and hypertensive patients（n=60） among 3 intubation devices： the MAC, the UE videolaryngoscopy ？（UE）, and the UE video intubation stylet ？（VS）. Cardiac index（CI）, stroke volume index（SVI）, heart rate（HR）, systolic blood pressure（SBP） and diastolic blood pressure（DBP） were recorded using Lidco Rapid V2？ preinduction, preintubation, and every minute for the first 5 min after intubation. We assessed oropharyngeal and laryngeal structures injury as well. Intubation time was significantly shorter than MAC groups（P〈0.001） only in UE group of normotensive and hypertensive patients. In normotensive patients, there were no significant differences in any of COP variables or hemodynamic variables among the three devices. In hypertensive patients, SBP and DBP in the MAC group were significantly higher（P〈0.05 or 〈0.01） than the UE and VS groups at 1, 2 and 3 min after intubation, but there were no significant differences in CI, SVI and HR among the three devices. There was no significant difference in oropharyngeal and laryngeal structures injury among all groups. It was concluded that both the UE and VS attenuate only the hemodynamic response to intubation as compared with the MAC in hypertensive patients, but not in normotensive patients.

Crystalloid and colloid preload for maintaining cardiac output in elderly patients undergoing total hip replacement under spinal anesthesia

The aim of the present study was to compare the effects of colloid and crystalloid preload on cardiac output （CO） and incidence of hypotension in elderly patients under spinal anesthesia （SA）. A randomized, double-blinded study was conducted including 47 elderly patients undergoing scheduled total hip replacement （THR）, who were randomized to three groups： the control group （C group, n = 15）, crystalloid （RS group, n =16） and colloid group （HES group, n = 16）. An intravenous preload of 8 mL/kg of either lactated Ringer’s solution in the RS group or 6% hydroxyethyl starch in the HES group was infused within 20 min before SA induction, while no intravenous preload was given in the C group. There was a trend of decrease in CO and systolic blood pressure after SA with time in the C group. In the RS and HES groups, CO increased significantly after fluid preloading as compared with baseline （P 0.01）. Thereafter, CO remained higher than baseline until 30 min after SA in the HES group. The change of systolic blood pressure was similar to CO, but no significant difference from baseline was observed in each group. Hypotension occurred in 3 patients in the C group and one each in the RS and HES group, respec-tively （P = 0.362）. Intravascular volume preload with colloid is more effective than crystalloid solution in main-taining CO, which may be improved the hemodynamic stability in elderly patients during SA.

Assessment of cardiac output in liver transplantation recipients

BACKGROUND:Liver cirrhosis causes peculiar systemic hemodynamics,and accurate evaluation of systemic hemodynamic state is important for cirrhotic recipients who underwent living donor liver transplantation(LDLT). We investigated the clinical advantages of a novel non- invasive method for measuring systemic hemodynamic parameters using indocyanine green(ICG). METHODS:Twenty-eight LDLT recipients were evaluated. Simultaneous measurements of cardiac output(CO)using Swan-Ganz catheters and pulse dye densitometry(PDD) were performed every 12 hours after LDLT.A total of 155 sets of simultaneous CO measurements were obtained. RESULTS:The CO values obtained by PDD correlated well with those obtained by the invasive catheter technique.In addition,none of the recipients developed any side-effects, and we verified the safety of repeated ICG injections.ICG is safe,even for repeated use over time in the same recipient. Moreover,PDD can measure the blood volume(BV).CONCLUSIONS:Since the cirrhotic systemic hemody- namics characterized by high CO and large BV remains, even after LDLT,the ability to measure CO and BV in a non-invasive,simple and real-time manner using PDD has advantages for cirrhotic LDLT recipients.

Continuous versus bolus cardiac output monitoring during orthotopic liver transplantation

BACKGROUND: Cardiac output monitoring is important for critical patients. This study aimed to determine the delayed response of continuous cardiac output (CCO) thermodilution measurement, whether CCO and bolus cardiac output (BCO) thermodilution agree sufficiently to be used interchangeably, and whether CCO monitoring is reliable for patients undergoing liver transplantation. METHODS: Thirteen patients undergoing liver transplantation without veno-venous bypass were studied (37-66 years old, weight 46-75 kg). Continuous and bolus thermodilution measurements were performed at predefined time points using an 'Opti-Q' SvO(2)/CCO monitor (Abbott Laboratories, North Chicago, IL, USA). Bias and 95% limits of agreement were calculated according to Bland and Altman analysis. The limits of agreement by which two methods are judged to be interchangeable were defined in advance as +/-(13%X BCO(mean)) L/min. The repeatability and relative error of CCO, and the differences between CCO and the mean of the two measurements were calculated. RESULTS: Cardiac output measurements yielded 196 data pairs with ranges of 1.9 to 17.9 L/min for CCO and 2.1 to 18.3 L/min for BCO. The response time of CCO was delayed in the early phases after caval clamping and after reperfusion. At most of the measurement points, bias and 95% limits of agreement were -0.18 +/- 1.91 L/min. 95% limits of agreement did not fall within the predetermined limits of agreement of +/- 1.14 L/min. The repeatability coefficient of CCO was 0.36 L/min and the relative error was 4.6 +/- 4.7%. The mean difference between CCO and the average of the two methods was -0.09 L/min (0.49 L/min). CONCLUSIONS: In patients undergoing liver transplantation, the delayed response of CCO limits its application during the early phases after caval clamping and after reperfusion of the graft. The two methods are not interchangeable even in hemodynamic stability. Continuous thermodilution monitoring, however, is reliable or acceptable for clinical purposes.

Anesthetics management of a renal angiomyolipoma using pulse pressure variation and non-invasive cardiac output monitoring: A case report

BACKGROUND Hypovolemic shock can lead to life-threatening organ dysfunction,and adequate fluid administration is a fundamental therapy.Traditionally,parameters such as vital signs,central venous pressure,and urine output have been used to estimate intravascular volume.Recently,pulse pressure variation(PPV)and non-invasive cardiac monitoring devices have been introduced.In this case report,we introduce a patient with massive active bleeding from giant renal angiomyolipoma(AML).During emergent nephrectomy,we used non-invasive cardiac monitoring with CSN-1901(Nihon Kohden,Tokyo,Japan)and PPV to evaluate the patient's intravascular volume status to achieve optimal fluid management.CASE SUMMARY A 30-year-old male patient with giant AML with active bleeding was referred to the emergency room complaining of severe abdominal pain and spontaneous abdominal distension.AML was diagnosed by computed tomography,and emergent nephrectomy was scheduled.Massive bleeding was expected so we decided to use non-invasive cardiac monitoring and PPV to assist fluid therapy because they are relatively easy and fast compared to invasive cardiac monitoring.During the surgery,6000 mL of estimated blood loss occurred.Along with the patient's vital signs and laboratory results,we monitored cardiac output,cardiac output,stroke volume,stroke volume index with a non-invasive cardiac monitoring device,and PPV using an intra-arterial catheter to evaluate intravascular volume status of the patient to compensate for massive bleeding.CONCLUSION In addition to traditional parameters,non-invasive cardiac monitoring and PPV are useful methods to evaluate patient's intravascular volume status and provideguidance for intraoperative management of hypovolemic shock patients.

Effect of cardiac output-guided hemodynamic management on acute lung injury in pediatric living donor liver transplantation

BACKGROUND Acute lung injury(ALI)after liver transplantation(LT)may lead to acute respiratory distress syndrome,which is associated with adverse postoperative outcomes,such as prolonged hospital stay,high morbidity,and mortality.Therefore,it is vital to maintain hemodynamic stability and optimize fluid management.However,few studies have reported cardiac output-guided(CO-G)management in pediatric LT.AIM To investigate the effect of CO-G hemodynamic management on early postoperative ALI and hemodynamic stability during pediatric living donor LT.METHODS A total of 130 pediatric patients scheduled for elective living donor LT were enrolled as study participants and were assigned to the control group(65 cases)and CO-G group(65 cases).In the CO-G group,CO was considered the target for hemodynamic management.In the control group,hemodynamic management was based on usual perioperative care guided by central venous pressure,continuous invasive arterial pressure,urinary volume,etc.The primary outcome was early postoperative ALI.Secondary outcomes included other early postoperative pulmonary complications,readmission to the intense care unit(ICU)for pulmonary complications,ICU stay,hospital stay,and in-hospital mortality.RESULTS The incidence of early postoperative ALI was 27.7%in the CO-G group,which was significantly lower than that in the control group(44.6%)(P<0.05).During the surgery,the incidence of postreperfusion syndrome was lower in the CO-G group(P<0.05).The level of intraoperative positive fluid transfusions was lower and the rate of dobutamine use before portal vein opening was higher,while the usage and dosage of epinephrine during portal vein opening and vasoactive inotropic score after portal vein opening were lower in the CO-G group(P<0.05).Compared to the control group,serum inflammatory factors(interleukin-6 and tumor necrosis factor-α),cardiac troponin I,and N-terminal pro-brain natriuretic peptide were lower in the CO-G group after the operation(P<0.05).CONCLUSION CO-G hemodynamic management in pediatric living-donor LT decreases the incidence of early postoperative ALI due to hemodynamic stability through optimized fluid management and appropriate administration of vasopressors and inotropes.

Application and Nursing of Pulse Index Continuous Cardiac Output (PiCCO) Volume Monitoring in Early Fluid Resuscitation in Patients with Septic Shock

Background: Septic shock is a rapidly changing and fatal syndrome that can cause comprehensive deterioration of cardiopulmonary and renal function and multiple organ failure. At the same time, septic shock has the complex clinical manifestations and hemodynamics. PiCCO can accurately monitor blood flow, physical and volume indicators, and active and effective fluid resuscitation are important measures to reduce the fatality rate of septic shock and improve the prognosis of patients. Objectives: To explore the application and nursing of PiCCO in early fluid resuscitation in patients with septic shock. Methods: This was a retrospective observational study. The observation group and the control group each had 30 cases. The observation group used PiCCO to guide fluid resuscitation;the control group used conventional methods to guide fluid resuscitation. The changes in CVP, HR, MAP, and urine volume per hour were observed in the two groups. The changes of various indicators before and after fluid resuscitation, the length of stay in ICU and the mortality rate were compared between the two groups. All the outcomes were collected from the electronic medical case system after patients’ discharge from the hospital. Results: APACHE II, CVP, HR, MAP were compared between the observation group and the control group, and the differences were statistically significant (P < 0.05). The blood volume of patients in the observation group was significantly improved after fluid supplementation (P < 0.05). Compared with the control group, the length of stay in ICU in the observation group was significantly shorter, and the mortality rate was also significantly reduced (P < 0.05). Conclusion: PiCCO can be better used in early fluid resuscitation of patients with septic shock.

Development of Surface Grating Distributed Feedback Quantum Cascade Laser for High Output Power and Low Threshold Current Density

We report on the room-temperature cascade laser （QCL） at λ -4.7μm. cw operation of a surface grating Both grating design and material distributed feedback （DFB） quantum optimization are used to decrease the threshold current density and to increase the output power. For a high-reflectivity-coated 13-μm-wide and 4- mm-long laser, high wall-plug efficiency of 6% is obtained at 20℃ from a single facet producing over I W of ew output power. The threshold current density of DFB QCL is as low as 1.13kA/cm^2 at 10℃ and 1.34kA/cm2 at 30℃ in cw mode. Stable single-mode emission with a side-mode suppression ratio of about 30 dB is observed in tile working temperature range of 20-50℃.

Application of pulse index continuous cardiac output system in elderly patients with acute myocardial infarction complicated by cardiogenic shock: A prospective randomized study

BACKGROUND Cardiogenic shock (CS) secondary to acute myocardial infarction (AMI) complicates management of the condition, and often leads to poor prognosis. Prompt and accurate monitoring of cardiovascular and accompanying hemodynamic changes is crucial in achieving adequate management of the condition. Advances in technology has availed procedures such as pulse index continuous cardiac output (PiCCO), which can offer precise monitoring of cardiovascular functions and hemodynamic parameters. In this study, PiCCO is evaluated for its potential utility in improving management and clinical outcomes among elderly patients with AMI complicated by CS. AIM To assess whether use of the PiCCO system can improve clinical outcomes in elderly patients with AMI complicated by CS.METHODS Patients from emergency intensive care units (EICU) or coronary care units (CCU) were randomized to receive PiCCO monitoring or not. The APACHE II score, SOFA score, hs-TnI, NT-proBNP, PaO2/FiO2 ratio and lactate levels on day 1, 3 and 7 after treatment were compared. The infusion and urine volume at 0-24 h, 24-48 h and 48-72 h were recorded, as were the cardiac index (CI), extravascular lung water index (EVLWI), intrathoracic blood volume index (ITBVI) and global end diastolic volume index (GEDVI) at similar time intervals. RESULTS Sixty patients with AMI complicated by CS were included in the study. The PiCCO group had a significantly lower APACHE II score, SOFA score, hs-TnI and NT-proBNP levels on day 1, 3 and 7 after treatment. The infusion and urine volume during 0-24 h in the PiCCO group were significantly greater, and this group also showed significantly higher ADL scores. Furthermore, the PiCCO group spent lesser days on vasoactive agents, mechanical ventilation, and had a reduced length of stay in EICU/CCU. Additionally, the CI was significantly higher at 48 h and 72 h in the PiCCO group compared with that at 24 h, and the EVLWI, ITBVI and GEDVI were significantly decreased at 48 h and 72 h. CONCLUSION Applying the PiCCO system could improve the clinical outcomes of elderly patients with AMI complicated by CS.

Assessment of Stroke Volume Variation Perioperatively by Using Arterial Pressure with Cardiac Output

Objective To observe the sensitivity of stroke volume variation(SVV) for assessing volume change during induction period of general anesthesia. Methods Patients who underwent orthopaedic surgery under general anesthesia and mechanical ventilation were divided into two groups randomly. Patients in the group Ⅰwere subjected to progressive central hypovolemia and correction of hypovolemia sequentially; patients in the Group Ⅱ were exposed to hypervolemia alone. Each step was implemented after 5 minutes when the hemodynamics was stable. SVV and cardiac index(CI) were recorded, and Pearson's product-moment correlation was used to analyze correlation between SVV and CI. Results Forty patients were included in this study, 20 cases in each group. For group Ⅰ patients, SVV was increased significantly along with blood volume reduction, and changes in CI were negatively correlated with changes in SVV(r=-0.605, P<0.01); SVV decreased significantly along with correction of blood volume; changes in CI were negatively correlated with changes in SVV(r=-0.651, P<0.01). For group Ⅱ patients, along with blood volume increase, SVV did not change significantly; changes in CI revealed no significant correlation with changes in SVV(r=0.067, P>0.05). Conclusion SVV is a useful indicator for hypovolemia, but not for hypervolemia.

Correlation of Electric Cardiometry and Continuous Thermodilution Cardiac Output Monitoring Systems

Purpose: Impedance Cardiography (ICG) with its drawbacks to reliably estimate cardiac output (CO) when compared to reference methods has led to the development of a novel technique called Electrical Cardiometry (EC). The purpose of this study was to compare EC-CO with the Continuous CO (CCO) derived from Pulmonary Artery Catheter (PAC). Methods: 60 patients scheduled to undergo coronary artery surgery necessitating the placement of PAC were studied in the operating room. Standard ECG electrodes were used for EC-CO measurements. Simultaneous CO measurement from EC and PAC was done at three predefined time points and were correlated. Results: A significant high correlation was found between the EC-CO and CCO at the three time points. Bland and Altman analysis revealed a bias of 0.08 L/min, a precision of 0.15 L/min, with a narrow limit of agreement (-0.13 to 0.28 L/min). The percentage error between the methods was 3.59%. Conclusion: The agreement between EC-CO and CCO is clinically acceptable and these two techniques can be used interchangeably. Mediastinal opening has no effect on the correlation between these two modalities.

Newer methods of cardiac output monitoring

Cardiac output(CO) is the volume of blood ejected by each ventricle per minute and is the product of stroke volume and heart rate. CO can thus be manipulated by alteration in heart rate or rhythm, preload, contractility and afterload. Moreover it gives important information about tissue perfusion and oxygen delivery. CO can be measured by various methods and thermodilution method using pulmonary artery catheter(PAC) is till date considered as gold standard method. Complications associated with PAC led to development of newer methods which are minimally or non-invasive. Newer methods fulfil other properties like continuous and reproducible reading, cost effective, reliable during various physiological states and have fast response time. These methods are validated against the gold standard with good level agreement. In this review we have discussed various newer methods of CO monitoring and their effectiveness in clinical use.

Comparison of Cardiac Output Measurement by Noninvasive Method with Electrical Cardiometry and Invasive Method with Thermodilution Technique in Patients Undergoing Coronary Artery Bypass Grafting

Objective: This study was conducted to compare the cardiac output by using Electrical Cardiometry (EC), a noninvasive method of continuous cardiac output monitoring during cardiac surgery with pulmonary artery catheter (PAC) derived cardiac output. Design: Prospective observational clinical study. Setting: Cardiac surgery operating room of a tertiary care cardiac center. Participants: Twenty five patients undergoing coronary artery bypass surgery with cardiopulmonary bypass. Measurements and Main Results: A total of 150 double data of cardiac output were compared with Thermodilution Cardiac Output (TDCO) and Thoracic Electrical Bioimpedance (TEBCO). The TDCO value ranges from 1.8-6.9 litre·min-1 with a mean of 4.39 ± 1.16 litre·min-1 and TEBCO ranges from 1.8-7.1 litre·min-1 with a mean of 4.21 ± 1.16 litre·min-1. The averaged Bland-Altman analysis for TDCO and TEBCO revealed that a mean bias was 0.18 and limit of agreement was -1.25 - 0.89 litre·min-1 and the percentage error (PE) ranged from 22%-32%. The precision for the TDCO was measured to be ±16.2% and the precision for TEBCO was ±19.6%. Receiver Operating Characteristic (ROC) curve analysis between TDCO and TEBCO with a cutoff of 15% shows a sensitivity of 84% and specificity of 63 and area under ROC curve of 0.80. Mountain plot between TDCO and TEBCO shows that a median percentile is 0.25 and value of 97.5 percentile is 1.525. Conclusions: The present study indicates that the electric cardiometry device yields numerically comparable results to cardiac outputs derived from the PAC during the cardiac surgery. Therefore, electrical cardiometry can be used to evaluate haemodynamic variables with clinically acceptable accuracy, when invasive methods are to be avoided or not available.

In Vitro Study of Hydrodynam ics at DifferentSimulated Cardiac Output for a Newly JiulingBileaflet Heart Valve Prostheses

Objective:To assess the hydrodynamic function of a newly China-made Jiuling bileaflet heart valve prosthesis at different simulated cardiac output.Methods:Jiuling valve,CarboMedics valve and C-L tilting disc valve have been tested in the aortic position of the pulsatile flow simulator.The testing condition is set at the simulated cardiac output of 2.0,3.0,4.0,and 5.0 L/min and a constant pulsatile frequency of 75 beats/min.The mean pressure difference(ΔP),leakage volume(LEV)and closing volume(CLV)across each valve,and the effective orifice area(EOA)have been analyzed.Results:The mean ΔP of all the Jiuling valves is in the range of below 10 mmHg and decreases with increasing the tissue annulus diameter.The ΔP of 25 mm CarboMedics is about 1.5 times of the same sized Jiuling valve and 27mm C-L tilting disc valve is about 71.8% higher than the same sized Jiuling valve.The EOA of the Jiuling mechanical valves increases with increasing the given cardiac output or the tissue annulus diameter,but 25 mm CarboMedics and 27 mm C-L tilting disc valve is similar to 21 mm and 23 mm Jiuling heart valve.The CLV of the Jiuling prosthetic cardiac valve is in the range of below 11%(normalized by stroke volume),25 mm Jiuling valve is about 56.4% lower than 25 mm CarboMedics and 27 mm Jiuling valve is about 11.4% higher than 27 mm C-L tilting disc valve.The LEV of the Jiuling prosthetic cardiac valves is in the range of below 28.9% (normalized by stroke volume),25 mm Jiuling prosthetic valve is about lower 27.3% than 25 mm CarboMedics and 27 mm Jiuling valve is about lower 11.2% than 27 mm C-L tilting disc valve.Conclusion:For a given tissue diameter,the newly Jiuling heart valve prostheses show more satisfactory hemodynamic characteristics at different cardiac output.

An Ultra-Low Quiescent Current CMOS Low-Dropout Regulator with Small Output Voltage Variations

An ultra-low quiescent current low-dropout regulator with small output voltage variations and improved load regulation is presented in this paper. It makes use of dynamically-biased shunt feedback as the buffer stage and the LDO regulator can be stable for all load conditions. The proposed structure also employs a momentarily current-boosting circuit to reduce the output voltage to the normal value when output is switched from full load to no load. The whole circuit is designed in a 0.18 μm CMOS technology with a quiescent current of 550 nA. The maximum output voltage variation is less than 20 mV when used with 1 μF external capacitor.

Comparison of the reproducibility of 2D doppler and 3D STIC in the measurement of fetal cardiac output

Objectives: Two methods have been described to assess fetal cardiac output (CO). It has usually been calculated by using 2D ultrasound to measure the diameter of outflow valves and Doppler ultrasound to measure flow velocity through the valves. Recently CO has been assessed using 3D spatio-temporal image correlation (STIC) to measure stroke volume. We aimed to compare the reproducibility of these techniques. Methods: In 27 women with singleton pregnancies, examinations were performed in three gestational age groups: 13 - 15, 19 - 21 and >30 weeks of gestation. Each mother was scanned once. Using 2D pulsed wave Doppler the duration of flow and average flow velocity in systole were measured through aortic and pulmonary valves. We averaged values from three consecutive Doppler complexes. The outlet valve diameters were measured and the cardiac output was calculated for each valve. The measurements were repeated to assess reproducibility. In the same women, we acquired STIC volumes of the fetal heart. The volume measurements were made using the 3D Slice method by one observer. Using 2 mm slices the circumference of the ventricles was traced at the end of systole and diastole to calculate ventricular volume before and after contractions to calculate stroke volume and hence cardiac output. The measurements were repeated to assess reproducibility. Results: The root mean square difference of log (CO) of repeat measurements ranged between 0.12 and 0.21 using Doppler compared to 0.7 to 1.47 using STIC. The differences in reproducibility reached statistical significance for both sides of the heart at all but one gestation. Conclusions: We found that Doppler assessment of fetal cardiac output was more reproducible than measurement using STIC.

Targeting PPARαin low ambient temperature exposure-induced cardiac dysfunction and remodeling

The present study demonstrates that the down-regulation of peroxisome proliferator-activated receptor-α(PPARα)results in chronic low ambient temperature(LT)exposure-induced cardiac dysfunction and remodeling,emphasizing the therapeutic potential of PPARαactivation strategies(e.g.,fenofibrate treatment)in LT-associated cardiac injury.

Validation of a Novel Method for Cardiac Output Estimation by CT Coronary Angiography

Background: Cardiac output can be estimated during retrospectively gated CT coronary angiography by anatomically determining left ventricular volumes;prospective triggering to minimize radiation precludes this methodology. We propose an alternative method for cardiac output estimation based on preclinical models suggesting that cardiac output may be inversely related to contrast washout from the aortic root during timing bolus scanning, as measured by peak aortic root contrast attenuation. Methods: 34 patients had CT coronary angiography timing bolus performed with 20 ml iodixanol at 5.5 ml/s followed by 20 ml normal saline at 5.5 ml/s through an 18-Ga antecubital catheter. Peak aortic root contrast attenuation was correlated to cardiac output calculated by echocardiography using heart rate stroke volume from biplane Simpson’s method.Results: Mean age was 58 ± 13 years;body surface area, 2.0 ± 0.5 m2. 53% were women. Stroke volume, cardiac output and cardiac index were 67 ± 19 ml, 4.5 ± 1.6 L/min, and 2.2 ± 0.7 L/min/m2, respectively. Peak aortic root contrast attenuation was 207 ± 46 HU and correlated to cardiac output and cardiac index with r = –0.64, p Conclusion: This novel method for cardiac output estimation by CTCA appears feasible. The CT physiologic parameters using the timing test-bolus data moderately correlated with echocardiographic assessment of cardiac output. The calculation of cardiac output adds important hemodynamic data to anatomic information provided by CTCA, and further development of this method may preserve assessment of left ventricular performance in prospective triggering.

Validation of the use of foreign gas rebreathing method for non-invasive determination of cardiac output in heart disease patients

Objective: To compare a new device (Innocor) for non-invasive measurement of cardiac output (CO) by foreign gas rebreathing method with conventional techniques used in the measurements of cardiac function. Methods: Cardiac outputs measured by Innocor (CORB) were compared with CO obtained by echocardiography (COEC), Swan-Ganz thermodilution (COTD), and left ventricle radiography (COLVR) in 34 patients subjected to cardiac catheterization. Values obtained from the four methods were analyzed by linear regression and paired values were compared by the method of Bland and Altman in SPSS. Results: There was strong positive correlation (r=0.94) between Innocor cardiac output values and the corresponding values obtained by ther-modilution and between COEC and COLVR values. Thermodilution appears to overestimate cardiac output when compared to the values obtained with Innocor by (0.66±0.22) L/min (P<0.0001). There was no correlation between data obtained by Innocor and the corresponding COEC and COLVR values. Conclusion: Innocor CORB is an easy, safe and well established method for non-invasive measurement of cardiac output with good prospects for clinical application in heart disease patients.