Septic shock, a prevalent critical condition in intensive care units (ICU) and a major cause of patient mortality, is fundamentally attributed to microcirculatory dysfunction. Traditional macrocirculatory parameters are often insufficiently sensitive to reflect microcirculatory status. Consequently monitoring peripheral microcirculatory function holds crucial significance for assessing disease progression and evaluating therapeutic efficacy in septic shock. The peripheral perfusion index (PPI), obtained from a standard pulse oximeter, is based on photoplethysmography (PPG). It calculates the differential absorption of red and infrared light emitted by the sensor between pulsatile arterial blood and non-pulsatile tissue, enabling real-time reflection of peripheral perfusion and thus providing non-invasive, continuous monitoring of microcirculatory function. Although often overlooked compared to other ICU monitoring parameters, PPI has demonstrated notable clinical advances in septic shock management. Specifically, in early identification, PPI combined with sequential organ failure assessment (SOFA) predicts disease progression, with its dynamic changes further aiding prognosis assessment. During fluid resuscitation, it guides fluid responsiveness evaluation and serves as a therapeutic target to optimize strategies. In circulatory support, it assists in determining vasoactive drug initiation timing and dosage titration. Additionally, PPI aids mechanical ventilation weaning and organ dysfunction evaluation. This article reviews the principles, influencing factors, and clinical application advances of PPI in septic shock, aiming to provide clinicians with a basis for individualized intervention, improved patient outcomes, and the advancement of precision medicine in septic shock management.
Humans ; Shock, Septic/therapy* ; Microcirculation ; Perfusion Index ; Prognosis ; Photoplethysmography