Cross et al identified many clinicians who don’t feel they have time to detect orthostatic hypotension (OH).1 Sixty-seven per cent took measurements within a minute of standing. This is in keeping with advice given by Juraschek et al, who found readings taken this soon correlate best with long-term adverse outcomes.2 The finding that many clinicians prefer to focus on a fall in systolic blood pressure (SBP)3 is also hard to criticise as there don’t appear to be much data about the prognostic significance of postural changes in diastolic blood pressure without an accompanying fall in SBP.
Cross et al also mention that many clinicians do not allow their patients a prolonged sitting period before standing. Although this period might allow a patient’s heart rate (HR) to settle, are we sure it is needed? If, instead, we paid attention to changes in a patient’s heart rate (HR) we might simply be able to ignore a fall in SBP when there is also a similar percentage fall in HR. Conversely, no study has ever looked at whether OH carries a worse prognosis when accompanied by orthostatic tachycardia.
One way to assess postural changes in both SBP and HR is to use the formula (SBP resting/SBP standing) × (HR standing/HR resting). Michael Witting, a professor of emergency medicine, first came up with it in 2003 as a means to detect hypovolaemia and called it Ratio of Orthostatic Shock Indices (ROSI).
Unlike most OH diagnosed in the community, Juraschek et al found 69.2% of hospital-diagnosed OH could be explained by potentially reversible conditions such as hypovolaemia and cardiovascular disease.4 One explanation might be that community clinicians prefer not to make a diagnosis of OH in patients who are acutely unwell. However, this might change if guidelines stated their patients didn’t have to stand for so long, and allow potential causes of shock, such as sepsis, to be detected at an earlier stage.5
- © British Journal of General Practice 2025
References
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