Table III.

Selected major impedance comparison studies of band electrode cardiac output measurement

Study setting	Eligibility criteria and patient group	Sample size	Method	R	Results and conclusions
Heart failure ICU18	Stable clinical condition: no respiratory distress, no increase in drug therapy	33	TD vs ICG	0.89	ICG gave good correlation with TD, but 21% of interpatient CO measurements differed by >15%.
Heart failure catheterization laboratory53	Ischemic and nonischemic cardiomyopathy	59	TD vs ICG Fick vs ICG (n = 28)	0.76 0.73	ICG correlates with TD and Fick for CO and CI, but ICG gives no correlation between thoracic fluid and PA wedge pressure. 62% sensitivity, 79% specificity to CO by TD.
Catheterization laboratory54	Pulmonary artery hypertension, clinically stable	39	TD vs ICG Fick vs ICG	0.8 0.84	Similar 3-way correlation of ICG with TD and Fick. 1.01 L/min precision, −0.43 L/min bias to CO by TD.
ICU university hospital14	NYHA stage IV, LVEF <30%, ischemic and dilated cardiomyopathy, transplant evaluation, no pacemaker, no renal failure	44	TD vs ICG	0.51	Only 31% of CO measurements were within ±0.5 L/min to TD, large interpatient variation from 0.2% to 133% difference. Caused by larger body size, more dyspnea, mitral/tricuspid valve regurgitation, not dependable for severe heart failure.
Heart hospital55	Ischemic cardiomyopathy, no pulmonary disease, no hypertension, no NYHA class IV (n = 25)	25	TD vs ICG	0.89	Similar high correlation to CO at rest and during exercise, hemodynamic changes in high-intensity exercise may reduce precision. Low 0.9% interpatient variation.
Hospital ICU56	Acute heart failure	31	TD vs ICG	0.85	Similar good correlation to CI at baseline and follow-up with vasodilation therapy. High correlation for whole-body impedance, 1.4 L/min precision.
Heart surgery ICU10	Within 24 h of post-CABG surgery	53	TD vs ICG	0.81	ICG agrees with TD for CO, better intrapatient correlation than TD.
Hospital ICU57	Post-CABG or valve surgery	20	TD vs ICG	0.93	All ICG data correlate to TD within ±20%, 0.4 L/(min m2) precision.
ICU university hospital58	Post-CABG or mitral valve surgery, no aortic valve defect	34	TD vs ICG	0.34	Good agreement preoperative CI measurement (R = 0.88), poor correlation for postoperative (R = 0.34). Large interpatient variation in bias (0.02–0.21 L/[min m2]) and precision (1.06–1.52 L/[min m2]). Variations caused by low flow, low mean arterial pressure, increased fluid and SVR.
Hospital ICU59	Post-CABG	50	TD vs ICG	0.49	Very high −0.33 L/min bias and 6.2 L/min precision. Better agreement with normal body dimensions and without mechanical ventilation (R = 0.65), worse correlation with deviation from normal anatomy and poor timing with ECG.

ICU, Intensive care unit; CABG, coronary artery bypass graft; TD, thermodilution; CO, cardiac output; CI, cardiac index; NYHA, New York Heart Association; LVEF, left ventricular ejection fraction; PA, pulmonary artery.