Microcirculatory alterations in critical care: A narrative review

Microcirculatory failure is recognised as a critical pathophysiological factor in the development of multi-organ failure in critically ill patients. However, traditional resuscitative efforts have focused on macrohaemodynamic variables such as blood pressure and cardiac output. These parameters may be insensitive for detecting changes in tissue perfusion when haemodynamic coherence is disturbed in states of shock. Several clinical studies using direct visualisation of the microcirculation have revealed that microcirculatory abnormalities can persist despite optimised global haemodynamic parameters. These abnormalities are independently associated with increased mortality. As the goal of resuscitation is to restore tissue perfusion, and the microcirculation closely reflects perfusion at the tissue level, interest in the microcirculation has grown over the years. Technological advances now allow direct observation and measurement of the microcirculation. This narrative review explores the current understanding of the microcirculation and its role in critical illness, with an overview of microcirculatory monitoring and its utility in clinical decision making.