PURPOSE: The most common method of monitoring cardiac output (CO) is thermodilution using pulmonary artery catheter (PAC), but this method is associated with complications. Impedance cardiography (ICG) is a non-invasive CO monitoring technique. This study compared the accuracy and efficacy of ICG as a non-invasive cardiac function monitoring technique to those of thermodilution and arterial pressure contour. MATERIALS AND METHODS: Sixteen patients undergoing liver transplantation were included. Cardiac index (CI) was measured by thermodilution using PAC, arterial waveform analysis, and ICG simultaneously in each patient. Statistical analysis was performed using intraclass correlation coefficient (ICC) and Bland-Altman analysis to assess the degree of agreement. RESULTS: The difference by thermodilution and ICG was 1.13 L/min/m², and the limits of agreement were −0.93 and 3.20 L/min/m². The difference by thermodilution and arterial pressure contour was 0.62 L/min/m², and the limits of agreement were −1.43 and 2.67 L/min/m². The difference by arterial pressure contour and ICG was 0.50 L/min/m², and the limits of agreement were −1.32 and 2.32 L/min/m². All three percentage errors exceeded the 30% limit of acceptance. Substantial agreement was observed between CI of thermodilution with PAC and ICG at preanhepatic and anhepatic phases, as well as between CI of thermodilution and arterial waveform analysis at preanhepatic phase. Others showed moderate agreement. CONCLUSION: Although neither method was clinically equivalent to thermodilution, ICG showed more substantial correlation with thermodilution method than with arterial waveform analysis. As a non-invasive cardiac function monitor, ICG would likely require further studies in other settings.
Arterial Pressure ; Cardiac Output ; Cardiography, Impedance ; Catheters ; Electric Impedance ; Humans ; Liver Transplantation ; Methods ; Pulmonary Artery ; Thermodilution

Calculation of cardiac hemodynamic parameters is based on accurate detection of feature points in impedance cardiogram. According to these parameters, doctors can determine heart conditions, so it is very important to accurately detect the feature point of impedance differential signals. This article presents a process in which we used wavelet threshold method to de-noise signals, and then detected the feature points after six layers wavelet decomposition by using bior3. 7. The experimental data were collected from healthy persons in our laboratory and twenty two clinical patients in Chongqing Daping Hospital by using KF_ICG instrument. The results indicated that this method could precisely detect feature points whether it was from healthy people or clinical patients. This helps to achieve the application of noninvasive detection cardiac hemodynamic parameters in clinical treatments by using impedance method.
Cardiography, Impedance ; Electric Impedance ; Heart ; physiology ; Hemodynamics ; Humans ; Wavelet Analysis

The principle of ambulatory cardiac output (CO) measuring technique is introduced in this paper. Experimental studies about the applicability of the two-compartment coaxial cylindrical model for ambulatory measurement of cardiac output with spot-electrodes have been carried out with using our newly-developed multi-channel impedance mapping system. The key factors using a spot-electrode array instead of a conventional band-electrode array for non-invasive CO) measurement are elaborated. The variations of the electric impedance pulsatile component (deltaZ waveform) and the two kinds of typical modes of deltaZ distributions measured by six electrodes on the midsternal (midian) line from the medial portion at the level of clavicle to the portion above the xiphisternum are discussed. The applicability of the two-compartment coaxial cylindrical model for ambulatory measurement of CO with spot-electrodes is analyzed. Synthesizing the deltaZ distributions and their typical changing models on the midsternal (midian) line during blood inflowing into aorta is the optimal positions of a pair of spot-electrodes for voltage pick-up at the level of clavicle for the upper electrode and the position at the level of nipple for the lower electrode when spot-electrode is being used to measure non-invasive CO.
Biomedical Engineering ; Cardiac Output ; physiology ; Cardiography, Impedance ; instrumentation ; methods ; Electrocardiography, Ambulatory ; instrumentation ; methods ; Electrodes ; Equipment Design ; Heart ; physiology ; Humans ; Models, Cardiovascular ; Thorax

BACKGROUND: The device-guided breathing (DGB) exercise is a non-pharmacological treatment of high blood pressure (BP). Changes in hemodynamic variables after DGB remain to be defined. This study evaluated the hemodynamic effects of DGB in hypertensive patients. METHODS: Fifty-nine hypertensive individuals (male, 56%; age, 44 +/- 10 years) with systolic BP (SBP) in the range of 140 to169 mm Hg and diastolic BP (DBP) < 105 mm Hg were divided into two group: control group (n = 17) vs. DGB group (n = 42) who slowed respiratory rate by using 15 minutes daily DBG (RESPeRATE) over 8 weeks. Heart rate, BP and hemodynamic parameters including cardiac index (CI), thoracic fluid content (TFC), systemic vascular resistance index (SVRI) and total arterial compliance index (TACI) were measured using the ICG Monitor (CardioDynamics) at baseline and study end. RESULTS: Baseline characteristics were not different between the two groups. Office BP (SBP/DBP) was reduced from baseline to end value by 13.2 +/- 11.1/6.9 +/- 7.5 mm Hg in DGB group and 2.2 +/- 6.9/0.5 +/- 6.6 mm Hg in control group (p = 0.001, p = 0.004, respectively). Heart rate, CI, stroke index, and TFC were not changed in both groups. However, the SVRI was lower and the TACI was higher in DGB group than control group (SVRI: 2,728 +/- 599 vs. 3,141 +/- 714 dyne sec m2/cm5, p = 0.002; TACI: 0.845 +/- 0.194 vs. 0.761 +/- 0.184 mm Hg/mL/m2, p = 0.041). CONCLUSIONS: Daily device-guided breathing exercise for 8 weeks lowers the BP mediated by reducing the systemic vascular resistance and increasing the total arterial compliance without changes in heart rate and CI.
Breathing Exercises ; Cardiography, Impedance ; Heart Rate ; Hemodynamics* ; Humans ; Hypertension ; Respiratory Rate ; Vascular Resistance

BACKGROUNDThe Medtronic InSync Sentry is the first available cardiac resynchronization therapy defibrillator (CRT-D) which can monitor fluid status by measuring intrathoracic impedance. This study was designed to observe the effectiveness of intrathoracic impedance monitoring on detecting aggravation of heart failure.

METHODSWe retrospectively analyzed the clinical data of 14 consecutive patients. Patients were regularly followed up every 3 - 6 months after the implantation. At each visit, interrogation of the device was done. Patients were instructed to inform the researcher on hearing the device alert, and to take extra 40 milligrams of furosemidum if they had aggravated symptoms later. If the symptoms could not be relieved, they were asked to see a doctor. Data about heart failure hospitalization were collected from the medical record.

RESULTSDuring 18 - 48 months follow-up, a total of 7 patients encountered 28 alert events. On one hand, alert events appeared before all deteriorated symptoms and heart failure hospitalizations. On the other hand, there were 23 alerts followed by deterioration of heart failure symptoms, and 2 alerts related to 2 hospitalizations caused by pulmonary infection in one patient. Only 5 patients were hospitalized 10 times for deterioration of cardiac function.

CONCLUSIONThe function of intrathoracic impedance monitoring is reliable in predicting deterioration of heart failure.

Adult ; Aged ; Aged, 80 and over ; Cardiac Resynchronization Therapy ; Cardiography, Impedance ; methods ; Female ; Heart Failure ; pathology ; therapy ; Humans ; Male ; Middle Aged ; Retrospective Studies

Principle of ambulatory cardiac output (CO) measuring technique is introduced in this paper. A lot of experimental studies of the current distribution on the thorax under the condition that the current injection electrodes were adhered to different positions were carried out by using a developed multi-channel impedance mapping system. The static impedance contour maps (Zo-map) and its pulsatile component contour maps (deltaZ-map) under different measuring conditions were analyzed, and the applicability of a two-compartment coaxial cylindrical model using a spot-electrode array instead of the conventional band-electrode array for ambulatory CO measurement, as well as the optimal spot-electrode array, were discussed. Based on the experimental results and the daily use of the ambulatory CO measuring technique, the optimal spot-electrode array meeting the condition of the two-compartment coaxial cylindrical model was determined as that a pair of spot-electrodes for current injection was located on the positions behind the ears and on the right lower abdomen, and a pair of spot-electrodes for voltage pick-up places on the medial portion at the level of clavicle and on the portion above the xiphisternum.
Cardiac Output ; physiology ; Cardiography, Impedance ; methods ; Electric Impedance ; Electrodes ; Equipment Design ; Humans

PURPOSE: Invasive determination of cardiac output (CO) is possible via a pulmonary artery catheter but catheter implantation has risks. Clinicians can assess CO safely using a non-invasive cardiac output device such as a commercially available doppler system (ultrasonic cardiac output monitor, USCOM, USCOM Ltd, Australia) or using impedance cardiography (ICG). The purpose of this study was to investigate the consistency of hemodynamic measurements between ICG and USCOM in shock patients. METHODS: From June 2007 to October 2007, we prospectively evaluated 21 patients with shock, who visited our emergency center. We measured CO and systemic vascular resistance (SVR) using ICG and USCOM on arrival, and at 30, 60, 90, and 120 minutes. RESULTS: The mean difference in CO between ICG and USCOM was 1.08+/-2.13 L/min. The percent limits of agreement (LOA) were -60.0 to 84.7% between ICG and USCOM. The correlation coefficient for CO between ICG and USCOM was 0.76 (p<0.01). CO values measured by ICG and USCOM were 4.3+/-1.7 vs 5.9+/-3.9 initially, 4.8+/-2.2 vs 6.0+/-3.9 at 30 min, 4.3+/-1.6 vs 5.1+/-2.9 at 60 min, 4.2+/-1.6 vs 4.9+/-2.7 at 90 min, and 4.1+/-1.6 vs 5.0+/-2.9 at 120 min, respectively. Statistical significance was observed within each modalities (p=0.03) but we did not find statistical significances between the two modalities. SVR (dynes*sec/cm5) values were measured by ICG and USCOM on arrival, and at 30, 60, 90, and 120 minutes. No statistical significance was seen within and between study groups. CONCLUSION: ICG and USCOM do not show clinically acceptable agreement.
Cardiac Output ; Cardiography, Impedance ; Catheters ; Emergencies ; Hemodynamics ; Humans ; Organothiophosphorus Compounds ; Prospective Studies ; Pulmonary Artery ; Shock ; Ultrasonography, Doppler ; Vascular Resistance

PURPOSE: While the use of coupling material (CM) during defibrillation is known to decrease transthoracic impedance more so than other materials elsewhere, the situation in Korea is unclear. The study assessed the use of paddleskin CM during defibrillation in South Korean emergency institutes (EIs) and measured the impedances. METHODS: From October 15 to October 19, 2009, 112 EIs (all of regional emergency medical centers (EMCs), specialized care centers, and local EMCs) were surveyed. Institute members were queried about their current use of paddleskin CMs during defibrillation. Indications for use were studied by means of a World Wide Web search, descriptions on the CM packaging, and telephone conversations with CM manufacturers and related people. Impedance measurements were recorded from April 13 to August 3, 2009. RESULTS: During defibrillation, 27 different CMs were used in the 108 EIs. Only nine institutes used CMs directly for defibrillation. Impedence of nine CMs could not be measured. The impedance values were 1.69, 1.71, 2.00, and 6.12 ohm for four CMs used for defibrillation; 6.66 and 11.94 ohm for two CMs used for electrodes; 9.71, 9.82, 11.57, 13.68, 13.89, 14.36, 18.31, and 19.66 ohm for eight CMs used for ultrasonography; and 14.05, 17.71, 35.44, and 41.15 ohm for four other CMs. CONCLUSION: More education and public information about the use of CMs for defibrillation are needed.
Academies and Institutes ; Cardiography, Impedance ; Electric Countershock ; Electric Impedance ; Emergencies ; Emergency Service, Hospital ; Internet ; Korea ; Product Packaging ; Republic of Korea ; Telephone

BACKGROUND: Thiopental sodium and propofol are commonly used to induce anesthesia. This study was conducted to compare the hemodynamic effects of propofol and thiopental sodium during the induction of general anesthesia in elderly patients. METHODS: Forty patients undergoing general anesthesia were randomly divided into two groups. In group T, thiopental sodium was used to induce anesthesia, whereas propofol was used in group P. Hemodynamic changes in the mean blood pressure, heart rate, cardiac index (as determined using a NICCOMO monitor) and bispectral index (BIS) during induction were then compared between the two groups. In addition, the dosage of induction agent, time required until loss of response to verbal order (LOV) and eyelid reflex were compared between groups. RESULTS: The mean blood pressure was significantly lower in group P than in group T during the 1-5 min following LOV and during the 2, 3 min following intubation (P < 0.05). However, the heart rate did not differ significantly between the two groups. The cardiac index also did not differ significantly between groups, except during the first 3 min following LOV. Finally, the BIS value were significantly lower than the baseline values in both groups during induction. CONCLUSIONS: In elderly patients, the heart rate, cardiac index and BIS value did not differ significantly between the two groups. But the mean blood pressure was significantly lower in propofol than in thiopental sodium.
Aged ; Anesthesia ; Anesthesia, General ; Blood Pressure ; Cardiography, Impedance ; Eyelids ; Heart Rate ; Hemodynamics ; Humans ; Intubation ; Propofol ; Reflex ; Thiopental

Age Factors ; Cardiac Output ; physiology ; Cardiography, Impedance ; methods ; Child ; Child, Preschool ; Electric Impedance ; Female ; Heart ; physiology ; Humans ; Male ; Stroke Volume ; physiology ; Tomography ; methods