Mean arterial pressure differences between cuff oscillometric and invasive blood pressure

Differences between automated cuff oscillometric blood pressure (BP) and invasive measurements are well described, but the causes are not fully understood. Automated BP devices record cuff oscillometric mean arterial pressure (MAP) as a key measurement step that is presumed to be accurate, but if not, could create error in cuff systolic (SBP) and diastolic BP (DBP) estimations. This has never been determined and was the aim of the study. Data from five studies with similar protocols were analysed (N = 262 patients undergoing coronary angiography, 61 +/- 11 years, 65% male). Cuff oscillometric MAP was measured using five different models of automated cuff BP devices simultaneous to invasively measured MAP (fluid-filled or solid-state catheters). Cuff SBP and DBP were estimated by device-specific algorithms. Differences (triangle) were calculated as cuff-invasive aortic BP. There were significant associations between triangle MAP and triangle SBP in four out of five devices (unstandardised beta range = 0.42-1.04). The triangle MAP explained 6-52% of the variance in triangle SBP. In the same four devices, there were significant associations between triangle MAP and triangle DBP (unstandardised beta range = 0.57-0.97) and triangle MAP explained 35-52% of the variance in triangle DBP. In conclusion, there are differences between cuff oscillometric MAP and invasive MAP which are associated with triangle SBP and triangle DBP. Further research is required to improve cuff oscillometric BP and greater transparency needed to understand algorithms used in these devices.