The Effect of Orthostatic Hypotension Detected Pre-Operatively on Post-Operative Outcome

Exacerbation of or new onset orthostatic hypotension in perioperative patients can occur. There is complex underlying pathophysiology with further derailment likely caused by acute cardiovascular changes associated with surgery. The implications for post-operative recovery are unclear, particularly in frail and older patients. We retrospectively explored patient notes for evidence of post-operative orthostatic intolerance in relation to pre-operative orthostatic hypotension.

Supine and 1-minute and 3-minute standing blood pressure measures obtained from adult patients before mainly general, orthopedic or uro/gynecology surgery were compared to post-operative outcome, specifically, evidence in patient notes about falls, feeling dizzy/unsteady and/or fearful to stand. Orthostatic hypotension was defined as a 20 mmHg or more and/or 10 mmHg or more fall in systolic and diastolic blood pressure, respectively, within ~3 minutes of standing after lying supine for an electrocardiogram.

Whilst all patients included had a 1-minute standing blood pressure assessment (N = 170), 3-minute assessment was performed less commonly (N = 113). Nevertheless, one-quarter (23.5%; N = 40) of 170 patients had pre-operative orthostatic hypotension. This was not clearly explained by cardiac or neurological disease or by common medications, but did occur more frequently in older patients and in those aged 65 years or more with higher clinical frailty scale scores. The COVID-19 pandemic reduced the number of patients progressing to surgery within the planned study timescale (N = 143/170; 84.1%). Nevertheless, patients with orthostatic hypotension stayed longer in hospital post-operatively and were more likely to have an episode of fall, unsteadiness and/or dizziness documented (un-prompted) in their notes.

These data provide further impetus for research into modifiable perioperative risk factors associated with orthostatic hypotension. These risks are not confined to those with a pre-existing dysautonomia diagnosis.