Focused Real-Time Ultrasonography for Nephrologists

Table 4

Comparison of techniques to assess intravascular volume and predict response to volume administration or removal.

Method	Circuit	Intervention	Threshold	“Gold standard”			Advantages	Disadvantages
Mean CVP [41]	Venous; “static”	Central line; Invasive	Mean CVP; mmHg	Increase of cardiac index 10–15%	76	62	None	Poor predictor of volume responsiveness [42]
Mean PAOP [43]	Pulmonary artery; “static”	Central line; Invasive	Mean PAOP; mmHg	Increase of cardiac index 15%	77	51	None	Poor predictor of volume responsiveness [42]
Right atrial pressure [44]	Venous; “dynamic”	Central line; Invasive	RAP variation mmHg	Increase in CO 250 mL/min			“Dynamic” RAP predicts volume responsiveness	Not routinely; available
IVC CI [41]	Venous; “dynamic”	Ultrasonography; Noninvasive		Increase of cardiac index 10–15%			Can differentiate overt volume depletion from overt overload. Ventilated or nonventilated patients.Readily available	Requires further validation. Operator dependent. Requires practice. Intermittent monitoring
Ventilated Tidal volume >8 mL/kg			IVC DI % = IVC CI %		77	85
Spontaneous breathing			IVC CI		31, 70	97, 80
IVC CI [45]	Venous; “dynamic”	Ultrasonography; Noninvasive	IVC CI %	Removal of >1 L by UF	64	64	As above	As above
IVCmax + IVC CI [46]	Venous; “dynamic”	Ultrasonography; Noninvasive	IVCmax cm + IVC CI %	Mean RAP >10 mmHg	82	67	As above	As above
RUSH exam [5]	Heart/venous; “dynamic”	Ultrasonography; Noninvasive	Cardiac function IVCmax + IVC CI	Final diagnosis of type of shock	88	96	As above	As above
Arterial line wave form analysis [41]	Arterial; “dynamic”	Arterial line with standard multiparameter monitor; Invasive		Increase of cardiac index 10–15%			Minimally invasive.; Continuous monitoring	Only validated with mechanical ventilation, no spontaneous breaths, and no arrhythmias.; Less reliable in automated systems [47].; Not validated in hypervolemia [48, 49]
Tidal volume <7 mL/kg			PPV %		72	91
Tidal volume 7 mL/kg					84	84
Controlled ventilation			SVV %		82 [48]	84–86 [41, 48]
Bioreactance + passive leg raising [50]	Arterial; “dynamic”	NICOM/ Cheetah^&apparatus; Noninvasive	Increase of SVI % after PLR	Increase of SVI >10% after volume administration	94	100	Continuous monitoring. Ventilated or nonventilated patients	Not validated in hypervolemia. Equipment may not be readily available

Sensitivity and specificity to predict response to volume administration or removal. Summary values for data from meta-analysis from Bentzer et al. [41] unless otherwise referenced.
After volume administration.
Only 13 of 14 data points for nonresponders and 17 of 19 data points for responders were extractable from the figure.
No sniff or valsalva.
Heterogeneous population with ventilated and nonventilated, pressors or no pressors, multiple comorbidities.
Cheetah Medical Inc., Portland, OR, USA.
SN = sensitivity, SP = specificity, CVP = central venous pressure, = number of studies from Bentzer et al. [41], PAOP = pulmonary artery occlusion pressure, CO = cardiac output, RAP = right atrial pressure, IVC CI = inferior vena cava collapsibility index, IVC DI = inferior vena cava distensibility index, UF = ultrafiltration, IVCmax = inferior vena cava maximum diameter, RUSH = rapid ultrasound in shock, PPV = pulse pressure variation, SVV = stroke volume variation, NICOM = noninvasive cardiac output monitor, SVI = stroke volume index, and PLR = passive leg raising.