Table 1.

Advanced hemodynamic monitoring in neonates.

Assessment of CO and intravascular volume
Method	Hemodynamic variables	Limitations	Invasiveness and monitoring frequency	Applicability
Neonatologist performed echocardiography (NPE)	CO, vena cava superior flow, shunts, structural and functional abnormalities Left ventricular end-diastolic volume Vena cava collapsibility	Intensive training Intra-/interobserver variability 20% Error in assessment of VTI (angle of insonation) and CSA	Non-invasive Intermittent	Clinical use (absolute values of CO) Preload assessment limited for clinical use
Transcutaneous doppler (USCOM®)	CO	Large interobserver variability Error in assessment of VTI (angle of insonation) and CSA No anatomical verification of sample area Low precision	Non-invasive Intermittent	Limited clinical use (trend monitoring)
Thoracic electrical bio-impedance (ICON®, NICOM®)	CO	Influenced by position of surface electrodes, changes in tissue water content (pulmonary edema, pleural effusion), alterations in heart rate and motion artifacts	Non-invasive Continuous	Clinical use (trend monitoring)
Arterial pulse contour analysis (APCA)	CO	Influenced by changes in vascular compliance, vasomotor tone, medication, irregular heart rate, and motion artifacts	Invasive	Research setting
	PPV, SVV, HRV	Influenced by physiological aliasing Frequent calibration necessary	Continuous	Research setting
TPTD	CO Hemodynamic volumes (GEDV, ITV)	Use of ice-cold saline Thermistor-tipped catheter needed Arterial (femoral) and central venous catheter needed Fluid overload after multiple injections	Invasive Continuous	Only >3 kg Research setting
TPUD	CO, shunt detection and quantification Continuous COHemodynamic volumes (TEDV, CBV, ACV)EVLW	Arterial and central venous catheter needed Risk of fluid overload after multiple injections	Invasive Intermittent Continuous measurement possible (APCA)	Clinical use (absolute values of CO)APCA as trend monitoring Research setting
Stop flow method	Mean systemic filling pressure	Venous and arterial access in the same extremity Influenced by physiological factors (higher thoracic and arterial compliance and low tidal volumes compared to adults) and physiological aliasing	Invasive Intermittent	Research setting
Plethysmograph variability index	Perfusion index Fluid responsiveness		Non-invasive Continuous	Research setting
Assessment of organ perfusion and oxygen delivery
Laser doppler flowmetry	Microcirculation (flow velocity)	Signal processing limitations Calibration problems Motion artifacts and probe pressure effects Influenced by skin temperature and vasopressors	Non-invasive Intermittent	Research setting
OPS, SDF, IDF	Microcirculation	Signal processing limitations (time-consuming) Effects of probe pressure Influenced by skin temperature, hemoglobin levels, and vasopressors	Non-invasive Intermittent	Research setting
NIRS	Regional blood flow, regional tissue oxygenation, and fractional tissue extraction	Lack of validation Considerable probe bias Different methods with different mathematical models Multiple assumptions Accuracy and precision questionable	Non-invasive Continuous	Clinical use (trend monitoring)

CO, cardiac output; VTI, velocity-time integral; CSA, cross-sectional area; PPV, pulse pressure variation; SVV, stroke volume variation; HRV, heart rate variability; TPTD, transpulmonary thermodilution; GEDV, global end-diastolic blood volume; ITBV, intrathoracic blood volume; TPUD, transpulmonary ultrasound dilution; TEDV, total end-diastolic volume; CBV, central blood volume; ACV, active circulating volume, EVLW, extra vascular lung water; OPS, orthogonal polarization spectral; SDF, sidestream darkfield imaging; IDF, incident dark field imaging; NIRS, near infrared spectroscopy.