Point of care venous Doppler ultrasound: Exploring the missing piece of bedside hemodynamic assessment

Table 1 Advantages and limitations of the Doppler evaluation of various veins

	Advantages	Limitations
Hepatic vein	Easy to acquire images from the same window used to assess IVC.	Prone to erroneous interpretation without simultaneous EKG tracing.
		Influenced by arrhythmias (e.g., S-wave can be smaller in atrial fibrillation), right ventricular systolic dysfunction.
		May never normalize in chronic pulmonary hypertension, structural tricuspid regurgitation irrespective of fluid status.
Portal vein	Easy to assess without EKG.	Not reliable in cirrhosis.
	Reliably changes with decongestive therapy - can monitor response to diuresis/ultrafiltration in real time.	Can be pulsatile in young, thin individuals without raised RAP.
	Tends to improve with decongestion, if not normalize even in chronic pulmonary hypertension.
Renal parenchymal vein	Simultaneous arterial tracing functions as a built-in EKG.	Difficult to obtain optimal images.
		Not studied in chronic kidney disease/patients with structural renal abnormalities.
		Interstitial edema may hamper improvement with decongestive therapy in real time (improves but lags behind decongestion).
		May never normalize in chronic pulmonary hypertension, structural tricuspid regurgitation irrespective of fluid status.
Femoral vein	Technically easier to acquire images of the vein.	Susceptible to excessive transducer pressure.
		Dependent on correct Doppler angle if measuring absolute velocities (pattern evaluation is less angle dependent).

IVC: Inferior vena cava; RAP: Right atrial pressure; EKG: Electrocardiogram.