Cardiac Output Measured by Transthoracic Impedance Cardiography at Rest, during Exercise and at Various Lung Volumes

1982 ◽  
Vol 63 (2) ◽  
pp. 107-113 ◽  
Author(s):  
A. T. Edmunds ◽  
S. Godfrey ◽  
Marion Tooley

1. Cardiac output measured by transthoracic impedance cardiography has been compared with simultaneous measurements made by the indirect Fick CO2 rebreathing method in nine adults and 14 children. All were healthy normal volunteers. Sixty-six comparisons were made at rest and during steady exercise at work loads up to 100 W. 2. Impedance measurements of cardiac output were consistently higher than indirect Fick measurements of cardiac output, but after application of a correction factor related to packed cell volume there was close correlation between the results obtained by the two methods (r = 0·94). 3. The mean coefficient of variation of impedance measurements of cardiac output was 13% at rest and 5% during steady-state exercise. 4. Changes of lung volume due to breath holding or resulting from addition of an expiratory resistance did not affect the measurement of cardiac output by impedance. 5. Transthoracic impedance cardiography is a rapid, non-invasive technique for measurement of cardiac output. It requires very little active co-operation from the subject. The method would probably give reliable results for patients with respiratory illnesses such as acute asthma or bronchiolitis, during which changes of lung volume may be expected to occur.

1995 ◽  
Vol 18 (9) ◽  
pp. 499-503 ◽  
Author(s):  
F. Pizzarelli ◽  
P. Dattolo ◽  
M. Piacenti ◽  
M.A. Morales ◽  
T. Cerrai ◽  
...  

We studied in 13 hemodialysis patients intradialytic variations of blood volume (BV) and cardiac output, by means of non-invasive methods. We found a weak correlation, r 0.2 or less, between BV variations and intradialysis blood pressure variations. The sensitivity of the former in describing the variations of the latter was only 32%. During the 30 min preceeding the hypotensive crisis the percent BV variations did not show any predictive trend. On the contrary, refilling increased as blood pressure dropped and a weak inverse relation (r -0.35) was found between these two parameters. Unstable patients had predialytic blood volume values significantly lower than stable ones and comparable to healthy subjects. On the contrary, the correlation between percent variations of cardiac output index and MAP was 0.68 with a sensitivity and specificity of 90% and 59%, respectively. Unfortunately these promising results were obtained only with an estimate of cardiac output obtained by echocardiography and not by transthoracic impedance cardiography, which is much more feasible than the former as on-line monitoring of cardiac output. On-line monitoring of hemodynamic parameters is an appealing but still unsolved task.


2021 ◽  
Vol 224 (2) ◽  
pp. S182-S183
Author(s):  
Zaid Diken ◽  
Antonio F. Saad ◽  
Sema Hajmurad ◽  
Rakesh Vadhera ◽  
Michelle Simon ◽  
...  

2021 ◽  
Author(s):  
Oya Köksal ◽  
Erdem Haberal

Abstract Purpose Simultaneous monitoring of ECG and thoracic electrical bioimpedance (TEB) is important in evaluating cardiovascular performance. TEB is a non-invasive technique based on measuring the impedance value that changes in the chest area depending on the heartbeat. Within the framework of this study, it can be used in home monitoring and biotelemetry applications to measure thoracic electrical bioimpedance (TEB), ECG and ICG. Methods Within the scope of this study, a four-electrode TEB measurement system was designed and built using the Raspberry Pi single board computer and its original monitor, ESP32 and EVAL-ADAS1000SDZ evaluation board. With the designed system, ECG and thoracic impedance measurements at 50 kHz current frequency were taken as real-time over a single channel. Delta_Z and ICG signals were created from thoracic impedance values with the developed software.ResultsWhile the thoracic impedance value varies between 15-45 Ω, the 67 thoracic impedance value measured with the designed system is approximately 1000 times the 68 reference value. The impedance change in the thoracic region was measured with the designed 69 system between 0.1-0.2 Ω values, and the compatibility of these values with reference values was 70 determined. While the reference value of the dZ / dt signal is 0.8 - 3.5 Ω / s, this value is between 2.3 - 71 5.3 Ω / s in the measurements taken with the designed system.Conclusion The prototype is achieved in detecting small changes in the thoracic impedance signal. The prototype is cheap, portable, small-sized and medically safe, so it is suitable for home care services and clinics. In addition, the developed system can be adapted to wearable technology. In order to increase the success of the system, the impedances values added to the thoracic impedance value should be determined and a calibration procedure should be established.


2019 ◽  
Vol 10 (1) ◽  
pp. 34-39
Author(s):  
Mohammad Karimi Moridani ◽  
Fatemeh Choopani ◽  
Mandana Kia

Abstract The purpose of this paper is to identify differences between abnormal and normal lung signals gathered by an EIT device, which is a new, non-invasive system that seeks the electrical conductivity and permittivity inside a body. Lung performances in patients are investigated using Phase Space Mapping technique on Electrical EIT signals. The database used in this paper contains 82 registered records of 52 individuals with proper lung volume. The results of this paper show that as the delay parameter (τ) increases, the SD1 parameter of phase space mapping indicates a significant difference between normal and abnormal lung volumes. The value of the SD1 parameter with τ = 6 in the case that the lung volume is in a normal condition is 342.57 ± 32.75 while it is 156.71 ± 26.01 in non-optimal mode. This method can be used to identify the patients’ lung volumes with chronic respiratory illnesses and is an accurate assessment of the diverse methods to treat respiratory system illnesses in addition to saving various therapeutic costs and dangerous consequences that are likely to occur by using improper treatment methods. It can also reduce the required treatment durations.


2013 ◽  
Vol 13 (3) ◽  
pp. 157-164 ◽  
Author(s):  
E. Pinheiro ◽  
O. Postolache ◽  
P. Girão

Impedance cardiography is a technique developed with the intent of monitoring cardiac output. By inspecting a few properties of the obtained signal (impedance cardiogram (ICG), the left ventricular ejection time can be derived with certainty, and an estimate of cardiac output is available. This signal is nowadays used in non-invasive monitoring, requiring the placement of electrodes over the subject’s skin, either ECG-type or in the form of encircling bands. The work here reported describes the implementation steps and the results obtained when embedding the ICG circuitry in a wheelchair’s backrest. The subject is seated normally, is normally dressed, and is completely unaware that monitoring is taking place. That means that the variation of tenths of ohm produced due to the cardiac cycle has to be detected with electrodes having substantial coupling impedance. Contactless ICG with embedded sensors was developed and tested on fourteen healthy subjects. The signal was always acquired, although respiratory activity is also important, constituting a noteworthy innovation in the area.


2021 ◽  
Vol 23 (Supplement_G) ◽  
Author(s):  
Gaetano Ruocco ◽  
Guido Pastorini ◽  
Mauro Feola

Abstract Aims Despite new therapeutic options, patients with heart failure (HF) still progress to advanced stage. Among new therapeutic options, Levosimendan was recently approved in order to treat patients hospitalized for acute decompensated heart failure (ADHF) with severe systolic dysfunction. The pharmacological effects of Levosimendan consist of inotropy, vasodilatation, and cardioprotection through the increase of calcium sensitivity. These effects should be monitored with echocardiography and in particular with speckle tracking and tri-dimensional echocardiography which appear to be useful in LV systolic function detection and monitoring. In this study we aim to evaluate the effect of slow infusion of Levosimendan on the non-invasive measurement of cardiac output, the speckle tracking parameters and the tri-dimensional echocardiography measurements in advanced ADHF patients. Methods and results This is a prospective observational study evaluating Levosimendan efficacy through advanced echocardiography. We enrolled 11 patients with diagnosis of ADHF who respect the recent ESC criteria of ‘advanced heart failure’. Patients underwent to blood sample examination to measure electrolytes, creatinine, and NTproBNP. Patients underwent to advanced echocardiography examination (performed for each patient pre- and post-Levosimendan infusion) with tri-dimensional echocardiography and global longitudinal strain assessment. Furthermore patients underwent to non-invasive cardiac output and cardiac index collection through impedance cardiography pre- and post-Levosimendan infusion. All patients were followed for 30 days after discharge for all cause of mortality and HF re-hospitalization. A total of 11 patients affected by advanced ADHF were included in this study. Mean age was 73.8 ± 4.7 years. 72.7% (n 8) patients were men. 81.9% (n 9) of patients recognize ischaemic heart disease as HF etiology. At admission mean systolic arterial pressure was 100 ± 17 mmHg, mean NTproBNP was 24 445 ± 12 194 pg/ml and mean serum creatinine was 1.55 ± 0.84 mg/dl. At tri-dimensional echocardiography mean LV ejection fraction (LVEF) was 19.7 ± 5.7% and at bi-dimensional echocardiography mean tricuspid anular plane systolic excursion (TAPSE) and pulmonary arterial systolic pressure (PASP) were, respectively, 12.5 ± 2.7 mm and 48 ± 16 mmHg. Mean LV global longitudinal strain (GLS) was −3.0 ± 1.8. Mean furosemide in-hospital infusion was 306 ± 102 mg/die and mean urine output 1436 ± 496 ml. None developed significant ventricular or supraventricular arrhythmias. All patients were treated with betablockers during infusion. At 30 days of follow-up two patients died and 1 patient was re-hospitalized. Evaluating the differences among our variables pre- and post-Levosimendan infusion, we found that NTproBNP was significantly reduced post-Levosimendan infusion (P = 0.01). Among ICG non-invasive measurement, we found significant differences in stroke volume (SV) and cardiac output (CO) in terms of significant improvement (P = 0.001 for both). Analysing tri-dimensional echocardiography variables, we observed a significant improvement of LVEF (P = 0.003), SV (P = 0.03) and 3-D LV GLS (P = 0.002). Furthermore, we observed a significant reduction in end-systolic volume (ESV) post-Levosimendan infusion (P = 0.02). Among bi-dimensional echocardiography measurements, there was a significant reduction in end-diastolic diameter of right ventricle (EDDRV) and in B-lines count (respectively, P = 0.02 and P = 0.002). Moreover, we observed a significant improvement in TAPSE (P = 0.003) and in LV GLS (P = 0.004). Conclusions Our study showed that slow Levosimendan infusion (12.5 mg at velocity of 0.05–1 mcg/kg/min) without bolus could be considered in advanced ADHF patients to improve cardiac performance without severe adverse events. ICG and echocardiography in-hospital evaluation seemed to be necessary to understand treatment success and patients status improvement as well as cardiac function benefit.


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