Cardiac Output Assessed by Invasive and Minimally Invasive Techniques

Table 1

Comparison of minimally invasive cardiac output monitoring techniques (CI: cardiac index, HR: heart rate, and ECG: electrocardiogram).

Technique	Advantages	Additional variables	Invasiveness	Limitations
LiDCO plus	Continuous CO measurement	SV	Arterial line	Requires good fidelity of arterial waveform
	Useful in goal-directed therapy	SVV	Peripheral or central venous line	Calibration affected by neuromuscular blockers
				Contraindicated in lithium therapy
				Requires transpulmonary lithium dilution calibration
PiCCO plus	Continuous CO measurement	GEDV	Arterial line	Requires good fidelity of arterial waveform
		EVLV		Requires transpulmonary thermodilution calibration
		SVV
		PPV
FloTrac/Vigileo	Continuous CO measurement	SVV	Arterial line	Requires good fidelity of arterial waveform
	No calibration required
NICO	Ease of use	Shunt	Endotracheal intubation	Affected by changes in dead space or V/Q matching
		Ventilatory variables	Valid only with PaCO2 > 30 mmHg
Bioimpedance	Noninvasive		Cutaneous electrodes	Affected by electrical noise, movement
	Continuous CO measurement			Electrode contact affected by temperature and humidity
				Requires hemodynamic stability
				Not useful in dysrhythmias
Bioreactance	Noninvasive Continuous CO measurement		Cutaneous electrodes
ECOM		SV	Endotracheal intubation	Coronary blood flow not recorded
		CI		Electrocautery produces interference
		SVR		No fully validated human studies
		HR, ECG
Ultrasound dilution	Measures flow in ECMO and hemodialysis circuits		Arterial line	Fluid overload with saline injection in sensitive patients
			Central venous catheterization	Errors from indicator loss in inadequate lung perfusion
				Errors in the presence of septal defects
TEE	Used to evaluate cardiac	SV	Esophageal probe	Mainly used perioperatively
	anatomy and function, preload, and myocardial ischemia
Esophageal Doppler	Useful in goal-directed therapy	SV	Esophageal probe	Measures only descending aortic flow
				Assumptions about aortic size may be erroneous