Hemodynamic Monitoring for the Evaluation and Treatment of Shock: What Is the Current State of the Art?

Hemodynamic monitoring has become a fundamental and ubiquitous, if not defining, aspect of critical care medicine practice. Modern monitoring techniques have changed significantly over the past few years and are now able to rapidly identify shock states earlier, define the etiology, and monitor the response to therapies. Many of these techniques are now minimally invasive or noninvasive. Basic hemodynamic monitoring and evaluation usually includes a focused physical examination and static hemodynamic vital signs: temperature, heart rate, respiratory rate, mean arterial pressure, and arterial hemoglobin oxygen saturation, typically measured with pulse photoplethysmography. When available, measurement of urinary output is often included. Advanced hemodynamic monitoring incorporates both noninvasive and invasive continuous hemodynamic monitoring. Noninvasive ultrasound has emerged as a fundamental hemodynamic evaluation tool and its use is now rapidly increasing. Invasive monitoring from arterial and central venous catheters, and occasionally pulmonary artery catheters, provides measurement of arterial pressure, intracardiac filling pressures, arterial and venous blood gases, and cardiac index. Minimally invasive and noninvasive measure of arterial pressure and cardiac output are also possible and often remain as accurate as invasive measures. Importantly, such advanced monitoring provides the foundation for goal-directed therapies for the treatment of shock. When coupled with functional hemodynamic monitoring analyses, these measures markedly extend the diagnostic and therapeutic potential of all monitoring modalities by defining preload reserve, vasomotor tone, cardiac performance, and tissue perfusion.