Learning Objectives: Intraosseous (IO) pressure monitoring has not been explored as a potential invasive monitoring option. The objective of this study was to describe IO pressure measurements and their relationship to blood pressure obtained via external blood pressure cuff in ICU patients. Methods: This is a prospective, convenience sample, proof of concept pilot study conducted in the medical and surgical ICUs at an urban, Level I trauma center. Patients were identified in the Emergency Department and enrolled under a waiver of informed consent. Inclusion criteria included: age >= 18 year old, presence of an IO placed by EMS or in the Emergency Department, and planned admission to the Medical or Surgical Intensive Care Unit. External cuff pressure readings were recorded every 15 min, and IO pressure data obtained via pressure transducer was recorded continuously for up to 12 hr. IO systolic, diastolic, and mean pressure (IO SBP, IO DBP, IO Mean) readings were summarized for the minute before and minute following an external cuff pressure reading. The ratios of IO pressures to external cuff pressures (IO Systolic Blood Pressure / Cuff SBP; IO DBP / Cuff DBP; IO Mean / Cuff Mean) were calculated. Results: Twenty patients were enrolled between January 2014 and May 2015. Average patient age was 60 (range = 45–81), and 80% were male. Primary diagnoses were mostly medical in nature. The average IO SBP, IO DBP, and IO mean were 35.41 ± 14.10 mm Hg, 30.51 ± 8.99 mm Hg, and 34.26 ± 9.98 mm Hg respectively. The ratio of IO SBP to cuff SBP, IO DBP to cuff DBP, and IO mean to cuff mean are 28.4 ± 11.7%, 31.9 ± 23.5%, and 32.3 ± 20.7% respectively. The correlation of determination (R2) for IO SBP to cuff SBP was higher than the relationship between diastolic and mean IOP to cuff pressure (range 0.05 – 0.66). There were no adverse events reported during the monitoring period. Conclusions: IO pressure was reliably obtained at roughly 30% of external blood pressure cuff readings. This method of pressure monitoring may be an alternative to invasive central monitoring in the future.