Transducer Levelling Errors in Everyday ICU Practice - A Multicentre Blinded Observational Study

Invasive pressure monitoring (arterial blood pressure via arterial catheter and central venous pressure via central venous catheter) is fundamental to clinical decision-making in intensive care. Treatment with vasopressors, fluids, and nursing interventions depends on accurate measurements. Because pressure transducers are hydrostatic, even small levelling errors can produce clinically relevant deviations (approximately 1 mmHg per 1.3 cm of vertical misplacement). Such errors may contribute to inappropriate therapy, for example under-recognition of hypotension, unnecessary vasopressor escalation, or missed venous congestion. This prospective, multicenter, blinded observational study will quantify transducer levelling deviations during routine ICU care and evaluate whether clinically relevant deviations are associated with treatment decisions. Adult mechanically ventilated ICU patients with an arterial catheter, a central venous catheter, and ongoing vasopressor therapy will be included at hospitals in Västra Götalandsregionen, Sweden. Two blinded reference lines/sensors will be placed at predefined physiological zero levels for MAP and CVP and connected in parallel to the patient monitoring system. Continuous deviation (mmHg) between the clinical transducer position and the blinded reference level will be recorded for 8 hours while clinical staff remain unaware of the reference setup. MAP/CVP-related treatment decisions (e.g., vasopressor adjustments, fluid therapy, and nursing interventions) will be recorded with timestamps. The study will provide real-world data on the magnitude and frequency of invasive pressure transducer misalignment in daily ICU practice and its potential relationship to patient management.