Understanding hypotension in surgical and critically ill patients From definitions to detection and prediction

This thesis examines the occurrence, detection, and prediction of hypotension in patients undergoing surgery or admitted to the Intensive Care Unit (ICU), a condition associated with postoperative complications, organ dysfunction, and mortality. Although hypotension is common and potentially preventable, its definition, monitoring, and management vary widely across clinical practice.
The thesis first reviews current definitions, incidence, and treatment strategies for hypotension in critical care settings. International survey data suggest that hypotension affects more than half of ICU patients and is often considered underdiagnosed. Despite its perceived impact on organ function and outcomes, many institutions do not use standardized treatment protocols.
Subsequent studies focus on postinduction hypotension (PIH), a common and largely iatrogenic event occurring after induction of general anesthesia. The findings show that PIH incidence depends strongly on the definition used and the monitoring approach. Modifiable factors, including anesthetic strategy and preemptive vasopressor administration, influence its occurrence, while routine fluid loading appears ineffective in preventing PIH.
The thesis also evaluates emerging approaches for predicting and detecting hypotension. Validation studies of the Hypotension Prediction Index, a machine-learning algorithm, show good predictive performance in both surgical and ICU populations, although its impact on clinical outcomes remains unclear. In addition, continuous noninvasive blood pressure monitoring devices show acceptable accuracy for mean and diastolic pressure and may detect hypotensive episodes that are missed with intermittent monitoring.
Overall, this work highlights the relevance of hypotension in perioperative and critical care medicine and supports efforts to improve consistency in definitions, monitoring, and management, with the aim of improving patient care.