Brachial-to-Radial Pressure Gradient in Critically Ill Patients Treated With Vasoactive Agents: A Prospective Observational Study

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Objectives: To determine the incidence of a significant noninvasive brachial-to-radial arterial pressure gradient (NIBR-APG) and its clinical associations in critically ill patients receiving vasoactive agents. Design: Prospective, multicenter, observational study. Setting: Thirteen ICUs in Poland. Patients: Adult ICU patients with radial arterial catheters receiving vasoactive agents hospitalized between April 2025 and July 2025. Interventions: None. Measurements and Main Results: Invasive radial mean arterial pressure (MAP) and noninvasive brachial MAP were measured twice and averaged. A NIBR-APG greater than 11 mm Hg was predefined as clinically significant. Baseline characteristics, hemodynamic variables, and outcomes were recorded. Among 303 patients, 49.5% were surgical admissions and 33.3% had septic shock. The median NIBR-APG was 4.5 mm Hg (interquartile range, 0.0–10.0 mm Hg). Fifty-six patients (18.4%) exhibited a NIBR-APG greater than 11 mm Hg. Compared with patients without a significant gradient, these patients received higher norepinephrine-equivalent doses (0.23 vs. 0.10 µg/kg/min), had higher Sequential Organ Failure Assessment scores (11 vs. 10), prolonged capillary refill time (3.0 vs. 2.5 s), and higher lactate concentrations (2.7 vs. 1.3 mmol/L). In multivariable analysis, only vasoactive drug dose was independently associated with NIBR-APG greater than 11 mm Hg (odds ratio, 1.68; 95% CI, 1.12–2.52). ICU mortality was higher in patients with significant gradients (48.0% vs. 30.1%). Conclusions: Nearly one in five critically ill patients receiving vasoactive agents demonstrated a clinically significant NIBR-APG. The presence of this gradient was independently associated with higher vasoactive drug requirements and was accompanied by greater illness severity and higher ICU mortality.