SMART-Height: Smartphone-based Measurement for Accurate and Reproducible Assessment of patient Height in the ICU

Background: Accurate measurement of patient height is critical in intensive care units (ICUs) for calculating ideal body weight, which directly guides weight-based interventions such as lung-protective ventilation settings and tidal volume adjustments. Currently, height estimation by ICU physicians and nursing staff is often unreliable, potentially leading to medical errors and suboptimal patient care. To overcome the challenges of measuring highly instrumented or immobile patients, contactless smartphone-based distance-measurement applications could offer a reliable, safe, and practical alternative in clinical practice.

Study Aim: first, to investigate whether the visual height estimations by nursing staff and physicians at the intensive care unit of the University Hospital Basel are indeed unreliable when compared to standard tape-measure readings with patient contact; second, to evaluate whether contactless height measurement using smartphone distance-measuring apps can provide a reliable and accurate assessment of patient height from a distance; and third, to determine whether this app-supported height measurement remains stable and reliable when performed by different healthcare professionals from various imaging heights and distances.

Methods This prospective observational study will be conducted in the intensive care unit of the University Hospital Basel. In the first phase, ICU physicians and nurses will visually estimate the height of a sample of ICU patients, and these subjective estimates will be compared against actual patient height measured using a standard manual tape measure. In the second phase, staff will use designated smartphone distance-measurement apps to evaluate patient height from a distance without direct patient contact. In the third phase, to test the robustness and inter-rater reliability of the digital tool, height measurements will be repeated by different healthcare professionals and systematically varied by altering the camera angle, height, and distance from the patient bed.