Monitoring Macro- and Microcirculation in the Critically Ill: A Narrative Review

Abstract

Circulatory shock is a common and important diagnosis in the critical care environment. Hemodynamic monitoring is quintessential in the management of shock. The currently used hemodynamic monitoring devices not only measure cardiac output but also provide data related to the prediction of fluid responsiveness, extravascular lung water, and also pulmonary vascular permeability. Additionally, these devices are minimally invasive and associated with fewer complications. The area of hemodynamic monitoring is progressively evolving with a trend toward the use of minimally invasive devices in this area. The critical care physician should be well-versed with current hemodynamic monitoring limitations and stay updated with the upcoming advances in this field so that optimal therapy can be delivered to patients in circulatory shock.

Keywords: circulatory shock; fluid responsiveness; hemodynamic monitoring; personalized hemodynamic monitoring.

Fig. 1

Frank-Starling curve. Patient at point 1 (steep part of curve) is more fluid responsive than patient at point B (flat part of curve).

Fig. 2

Systolic pressure variation (SPV). dDown, delta down; dUP, delta UP.

Fig. 3

Stroke volume variation (SVV). SVmax, maximum stroke volume; SVmin, minimum stroke volume.

Fig. 4

Pulse pressure variation (PPV). PPmax, maximum pulse pressure; PPmin, minimum pulse pressure.

Fig. 5

Algorithm for guiding fluid resuscitation in patients with shock on the basis of fluid responsiveness. SPV, systolic pressure variation; SVV, stroke volume variation; PPV, pulse pressure variation; PLR-cCO, passive leg raising-induced change in cardiac output; FoCUS, focus cardiac ultrasound; Lung USG, lung ultrasonography.

Fig. 6

Hemodynamic monitoring devices in intensive care unit (ICU) settings. ECG, electrocardiography; NIBP, noninvasive blood pressure; SpO2, oxygen saturation; CVP, central venous pressure; IABP, invasive arterial blood pressure; SVV, stroke volume variation; EEOT, end-expiratory occlusion test; PLR, passive leg raising; TPTD, transpulmonary thermodilution; EVLW, extravascular lung water; PVPI, pulmonary vascular permeability index; CO, cardiac output; RV, right ventricle; PAH, pulmonary artery hypertension; LV, left ventricle; ARDS, acute respiratory distress syndrome; PAC, pulmonary artery catheter.