Whole-body Impedance Cardiography Research Articles

Impaired myocardial function in newly onset Type 2 diabetes associates with arterial stiffness☆

The aim of this study was to evaluate myocardial function using pulsed and color-coded tissue Doppler imaging (TDI) and vascular wall elasticity using whole-body impedance cardiography (ICG) in patients with newly diagnosed Type 2 diabetes mellitus (DM2), and to compare the measurements with those of healthy controls. Systolic (SBP) and diastolic (DBP) blood pressure and glycosylated hemoglobin (HbA1c) were measured in 49 men (mean age 52.3+/-5.6 years, duration of DM2 1.8 years), and 15 healthy male control subjects (48.3+/-7.4 years). Mitral annular peak systolic (Svm), early (Evm), and late (Avm) diastolic velocities as well as myocardial peak systolic (Sv), early (Ev) and late diastolic (Av) velocity from middle segments of the anterior, inferior and lateral wall and the inferior septum were measured by TDI. ICG at rest was used to measure cardiac index (CI) and pulse wave velocity (PWV). The patients had higher body mass index (BMI 29.1+/-3.7 vs. 25.2+/-2.4 kg/m(2), p=0.000) and SBP (142+/-15 vs. 120+/-7 mmHg, p=0.005) than the controls, CI was comparable (2.8+/-0.5 vs. 2.8+/-0.6l/min/m(2)). The patients had lower age adjusted myocardial Sv (3.8+/-1.1 vs. 4.8+/-1.1cm/s, p=0.002) and Ev (4.6+/-1.6 vs. 6.2+/-1.7 cm/s, p=0.011), and also mitral annulus peak early diastolic velocity (Evm 7.8+/-1.9 vs. 10.4+/-2.6 cm/s, p=0.001). In diabetic patients PWV (14.2+/-2.7 vs. 10.0+/-1.7 m/s, p=0.002) was higher. Age (r=-0.39, p=0.001), BMI (r=-0.44, p=0.000) and PWV (r=-0.52, p=0.000) correlated significantly with Evm. PWV correlated with age (r=0.50, p=0.000), SBP (r=0.67, p=0.000), and HBA1c (r=0.36, p=0.010). In stepwise regression analysis, PWV (beta=-0.39, p=0.000) was the major determinant of Evm. Myocardial function is impaired in asymptomatic patients with newly detected DM2 consistent with diabetic heart muscle disease. Arterial stiffness is strongly related to myocardial dynamics, and both may have the same pathophysiologic background.

Maternal Hemodynamics During Cesarean Delivery Assessed by Whole-Body Impedance Cardiography

Whole-body impedance cardiography (ICG W B ), a noninvasive procedure that provides continuous data on cardiac output, was used to assess hemodynamics and cardiovascular responses during elective cesarean section performedunder spinal anesthesia in 10 healthy women with normal pregnancies. Five of these women were nulliparous. Two pregnant women with heart disease also were studied; one had aortic valve stenosis, and one had operated tetralogy of Fallot. Mean arterial pressure (MAP), heart rate (HR), stroke index (SI), cardiac index (CI), and systemic vascular resistance index (SVRI) were recorded during surgery, as anesthesia lightened, and 2 to 5 days postpartum. There were significant changes in all hemodynamic parameters over time (Fig. 3). Preloading increased both MAP and HR, but did not alter SI or CI. Spinal anesthesia led to lower SVRI, and MAP was significantly lower than after preloading. The CI and SI, however, remained unchanged. SVRI increased significantly in hypotonic patients given an infusion of ephedrine. Immediately after delivery, CI increased 47% over baseline and 34% from predelivery values. Both HR and SI increased significantly, but the MAP was stable-presumably because of a 39% decrease in SVRI. These changes lasted approximately 10 minutes on average but continued for 30 minutes in one instance. When ephedrine was not infused, hemodynamic responses to delivery resembled those in hypotonic patients. Baseline hemodynamic values returned after spinal blockade resolved. MAP was below baseline in the early postpartum period. CI was stable and SVRI tended to decline. The woman operated on for tetralogy of Fallot had normal baseline hemodynamic values. In the woman with aortic valve stenosis, the CI and the SI did not increase after delivery and pulmonary edema developed, from which she recovered completely. This experience indicates that ICG W B may provide a useful noninvasive means of monitoring hemodynamic changes during cesarean delivery.

Atrial fibrillation in elderly patients after cardiac surgery: Postoperative hemodynamics and low postoperative serum triiodothyronine

The purpose of this study was to evaluate serum triiodothyronine levels as a trigger of postoperative atrial fibrillation (AF) in elderly patients undergoing cardiac surgery and to study the possible association of serum triiodothyronine levels with preoperative and postoperative hemodynamics. Prospective study. University hospital. Forty-six consecutive nonemergency patients 65 years or older undergoing cardiac surgery during 1999 to 2000 in Tampere University Hospital, Tampere, Finland. Free serum T3 concentration was used as a measure of serum triiodothyronine levels. Samples were taken preoperatively, on the fourth postoperative day, and at the 3-month follow-up. The hemodynamic state of the patients was estimated by whole-body impedance cardiography preoperatively, during the intensive care unit period, daily until the fourth postoperative day, and at the 3-month follow-up. AF occurred in 43% of the patients. The patients in the AF group had significantly more grafts (3.9 v 3.1, p = 0.02), and there was a small difference in age between the AF and non-AF groups (73 years v 69 years, p = 0.06). The free T3 concentration on the fourth postoperative day was significantly lower in the AF group (3.5 nmol/L v 4.6 nmol/L, p = 0.04). In logistic regression analysis, the independent predictors of AF were age, number of grafts, and serum free T3 concentration on the fourth postoperative day. In the group with low T3 concentration, the cardiac index was lower (1.4 v 1.8, p = 0.05) and the systemic vascular resistance index was higher (4,064 v 2,969, p = 0.04) but only immediately after the operation. Although the AF mostly appeared during the second to fourth postoperative days, there were no longer any differences in the hemodynamic state at that time. In a group of elderly patients undergoing cardiac surgery, there was a strong association between a postoperative decrease of serum triiodothyronine levels and atrial fibrillation. The decrease of serum triiodothyronine levels was related to the changes of hemodynamic parameters only in the immediate postoperative period.

Maternal hemodynamics during cesarean delivery assessed by whole‐body impedance cardiography

This descriptive study was designed to evaluate maternal hemodynamics and cardiovascular responses to delivery during cesarean section (CS) under spinal anesthesia. We also assessed the feasibility of a noninvasive and continuous method of measuring cardiac output, namely whole-body impedance cardiography (ICG(WB)), during elective CS. Because of the techniques used in previous studies, only fractionated data on maternal hemodynamics during CS are available to date. We studied 10 healthy women with normal pregnancies and two pregnant women with heart disease undergoing elective CS. Mean arterial pressure (MAP), heart rate (HR), stroke index (SI), cardiac index (CI) and systemic vascular resistance index (SVRI) were recorded continuously during CS, during the period of dissipation of anesthesia and on the second to fifth postpartum day. Analysis of variance for repeated measurements (anova) and the paired sample t-test were used in statistical analysis. The hemodynamic parameters could be registered continuously during the whole procedure. At the point of delivery, a 47% increase in CI and a 39% decrease in SVRI were recorded, while MAP remained stable. These changes occurred within 2 min of delivery of the newborn and persisted on average for 10 min. Sudden and significant hemodynamic changes take place at the moment of delivery. Intact physiological cardiovascular compensation mechanisms are needed to adapt to these challenges. Whole-body impedance cardiography may offer a useful noninvasive tool to monitor hemodynamics during cesarean section.

Maternal hemodynamics during cesarean delivery assessed by whole-body impedance cardiography

Background. This descriptive study was designed to evaluate maternal hemodynamics and cardiovascular responses to delivery during cesarean section (CS) under spinal anesthesia. We also assessed the feasibility of a noninvasive and continuous method of measuring cardiac output, namely whole-body impedance cardiography (ICGWB), during elective CS. Because of the techniques used in previous studies, only fractionated data on maternal hemodynamics during CS are available to date. Methods. We studied 10 healthy women with normal pregnancies and two pregnant women with heart disease undergoing elective CS. Mean arterial pressure (MAP), heart rate (HR), stroke index (SI), cardiac index (CI) and systemic vascular resistance index (SVRI) were recorded continuously during CS, during the period of dissipation of anesthesia and on the second to fifth postpartum day. Analysis of variance for repeated measurements (anova) and the paired sample t-test were used in statistical analysis. Results. The hemodynamic parameters could be registered continuously during the whole procedure. At the point of delivery, a 47% increase in CI and a 39% decrease in SVRI were recorded, while MAP remained stable. These changes occurred within 2 min of delivery of the newborn and persisted on average for 10 min. Conclusion. Sudden and significant hemodynamic changes take place at the moment of delivery. Intact physiological cardiovascular compensation mechanisms are needed to adapt to these challenges. Whole-body impedance cardiography may offer a useful noninvasive tool to monitor hemodynamics during cesarean section.

The Vasodilatory Effect of Alfuzosin and Tamsulosin in Passive Orthostasis: A Randomised, Double-Blind, Placebo-Controlled Study

Objective: To compare in details the effects of urologically used α 1-blockers alfuzosin and tamsulosin on the cardiovascular responses to passive orthostasis. Methods: The responses to passive orthostasis (tilt provocation at 60° for 8 min) were measured in normotensive healthy volunteers with finger blood pressure method and whole-body impedance cardiography prior to the administration of the drugs as well as three days after the beginning of the randomised, double-blind medications. The parallel treatments were standard clinically used doses of α 1-blockers alfuzosin (5 mg twice daily, n = 10), tamsulosin (0.4 mg once daily, n = 10), or placebo ( n = 11). Results: When measured prior to the head-up tilt test in supine position, neither alfuzosin nor tamsulosin significantly changed any of the cardiovascular variables. During the passive orthostasis, however, both tamsulosin and alfuzosin reduced systemic vascular resistance index compared to pre-drug responses (−540 and −462 dyn s/cm 5 m 2, respectively, p < 0.05). Both drugs also augmented orthostatic responses of heart rate (11 and 9 bpm, respectively, p < 0.05) and cardiac index (0.50 and 0.40 l/min/m 2, respectively, p < 0.05) but not those of stroke index when compared to the responses during placebo or before the administration of the drugs. The alfuzosin and tamsulosin groups did not significantly differ from each other in terms of any parameter. Conclusions: Both alfuzosin and tamsulosin have clear cardiovascular effects, which are most strikingly evident in the influences on systemic vascular resistance and cardiac output.

Cardiac output measurement after coronary artery bypass grafting using bolus thermodilution, continuous thermodilution, and whole-body impedance cardiography

Objective: To test the feasibility of continuous cardiac output (CO) monitoring with whole-body impedance cardiography after coronary artery bypass grafting and to compare the values obtained with those measured using the bolus and continuous thermodilution methods. Design: A prospective study. Setting: Intensive care unit in a university hospital. Patients: Twenty patients after coronary artery bypass grafting. Interventions: CO was measured intermittently using the bolus thermodilution method, and continuously using the continuous thermodilution method, and whole-body impedance cardiography immediately after transfer to the intensive care unit. Measurements and Main Results: Bolus thermodilution CO was measured in triplicate at up to 14 time points overnight. Continuous thermodilution CO and whole-body impedance cardiography CO values were recorded simultaneously. During the study period, the bias in CO values between bolus thermodilution and whole-body impedance cardiography ranged from 0.07 to 1.05 L/min and the precision (standard deviation of differences) ranged from 0.82 to 1.31 L/min. The bias between the bolus and continuous thermodilution methods ranged from 0.06 to 0.58 L/min and the precision from 0.43 to 1.02 L/min. Pulmonary artery temperature and CO level were the major determinants of the bias and precision in both comparisons. Conclusions: Agreement between whole-body impedance cardiography and bolus thermodilution is slightly inferior to that between the bolus and continuous thermodilution methods but not to the extent that it hampers the use of whole-body impedance cardiography for the continuous monitoring of CO after coronary artery bypass surgery. © 2003 Elsevier Inc. All rights reserved.

Simultaneous non-invasive assessment of arterial stiffness and haemodynamics - a validation study.

The purpose of the study was to estimate the reliability of whole-body impedance cardiography (ICGWB)-derived pulse wave velocity (PWV) and stroke volume index to pulse pressure (SI/PP) measurements. The repeatability and reproducibility of ICGWB parameters were also determined. Agreement between the impedance and Doppler ultrasound-based PWV measurements was estimated in 25 healthy subjects in two consecutive measurements. Impedance-derived SI/PP (SIICG/PP) estimates were compared with simultaneously measured SI/PP based on thermodilution (SITD/PP) and direct Fick (SIFICK/PP) methods in 30 surgical patients. PWV measured between the aortic arch and popliteal artery using the impedance technique with selective electrode configuration (PWVIS) agreed well with the Doppler ultrasound method (PWVDOPP), the bias (PWVDOPP - PWVIS) and precision (+/- SD of differences) being 0.00 and 0.79 m s-1, respectively. PWV derived from the whole-body and popliteal impedance plethysmograms (PWVICG) overestimated slightly PWVDOPP values. The repeatability value for PWVIS was excellent, being 0.54 m s-1. The reproducibility values for PWVDOPP and PWVIS were very similar (2.17 and 2.42 m s-1, respectively). Changes in PWVIS correlated strongly with changes in PWVDOPP (r=0.74; P<0.0001), indicating that both methods reflected the true physiological variation in PWV. The agreement between SIICG/PP and SITD/PP or SIFICK was almost identical to the agreement between the SITD/PP and SIFICK/PP. In conclusion,whole-body impedance cardiography provides handy and reliable means of evaluating arterial stiffness on the basis of PWV and SI/PP simultaneously with conventional haemodynamic parameters. The method is highly repeatable and reproducible.

Effects of hypertonic saline (7.5%) on extracellular fluid volumes compared with normal saline (0.9%) and 6% hydroxyethyl starch after aortocoronary bypass graft surgery

Objective: To compare the effects of hypertonic (7.5%) saline (HS), normal (0.9%) saline (NS), and 6% hydroxyethyl starch (HES) on extracellular fluid volumes in the early postoperative period after cardiopulmonary bypass. Design: A prospective, randomized, double-blind study. Setting: University teaching hospital. Participants: Forty-eight patients scheduled for elective coronary artery bypass graft surgery. Interventions: Patients were randomly allocated to receive 4 mL/kg of HS, NS, or HES during 30 minutes when volume loading was needed during the postoperative rewarming period in the intensive care unit. Plasma volume was measured using a dilution of iodine-125-labeled human serum albumin. Extracellular water and cardiac output were measured by whole-body impedance cardiography. Measurements and Main Results: Plasma volume had increased by 19 ± 7% in the HS group and by 10 ± 3% in the NS group (p = 0.001) at the end of the study fluid infusion. After 1-hour follow-up time, the plasma volume increase was greatest (23 ± 8%) in the group receiving HES (p < 0.001). The increase of extracellular water was greater than the infused volume in the HS and HES groups at the end of the infusion. One-hour diuresis after the study infusion was greater in the HS group (536 ± 280 mL) than in the NS (267 ± 154 mL, p = 0.006) and HES groups (311 ± 238 mL, p = 0.025). Conclusion: The effect of HS on plasma volume was short-lasting, but it stimulated excretion of excess body fluid accumulated during cardiopulmonary bypass and cardiac surgery. HS may be used in situations in which excess free water administration is to be avoided but the intravascular volume needs correction. Copyright © 2001 by W.B. Saunders Company

Non-invasive cardiac output determination: state of the art

This review deals with recent developments in non-invasive cardiac output measurement. In the past few years significant progress has been made with semi-invasive transoesophageal echocardiography; the method now provides advanced facilities to measure cardiac output and other important characteristics of cardiac function. The method is, however, operator-dependent and the equipment used is expensive, which means that large-scale use on intensive care patients is not feasible. Whole-body impedance cardiography has recently shown good accuracy and flexibility in use, and seems to be the most promising method for the non-invasive measurement of cardiac output.

An advanced non-invasive method to study the cardiovascular system: The whole-body impedance cardiography (ICG WB)

An advanced non-invasive method to study the cardiovascular system: The whole-body impedance cardiography (ICG WB)