Primary aim: Determine feasibility of investigating IOH using continuous beat-to-beat blood pressure measurement during a standardised mobilisation protocol i) preoperatively and ii) postoperatively at 6 and 24 hours following THA/TKA.
Secondary aim: Assess incidence of IOH and OI-type events i) preoperatively and ii) postoperatively at 6 and 24 hours following THA/TKA.
Prospective observational feasibility study of 20 TKA and 20 THA participants. Baseline assessments occurred within two weeks preoperatively and included i) sociodemographics and anthropometrics, ii) two tests for orthostatic intolerance including an active stand test, and a standardised mobilisation protocol with continuous blood pressure monitoring using the Finapres NOVA®. Postoperatively, the standardised mobilisation protocol was implemented with continuous blood pressure measurement at 6 hours and 24 hours by a physiotherapist. Feasibility outcomes included recruitment and retention rates, time for data collection, and fidelity of data collection. OI-type events were defined as the percentage of patients who were unable to complete the standardised mobilisation protocol due to symptoms of orthostatic intolerance.
We screened 61 potential participants, recruited 43 participants, and present complete data for 36 participants (recruitment rate 71%), with an 84% retention rate. Preoperatively, the time for data collection was 64 mins (SD 14). Postoperatively, the time taken for data collection during the standardised mobilisation protocol at 6 and 24 hours was 28 mins (SD 12) and 27min (SD 8) respectively. We observed good data fidelity with 79-100% of valid data points collected at all stages of the standardised mobilisation protocol.
Preoperatively, 33% of participants experienced symptoms of orthostatic intolerance during the active stand test, indicating a positive test. The incidence of OI-type events during standardised mobilisation protocol was i) 0% preoperatively and ii) 40% and 26% postoperatively at 6 and 24 hours respectively.
Incidence of IOH was i) 44% during the preoperative active stand test and ii) 24% preoperatively and 47% and 34% at 6 and 24 hours respectively during standardised mobilisation protocol.
There was a significant association between IOH during preoperative standardised mobilisation protocol with symptoms of orthostatic intolerance during standing up (Likelihood-ratio chi-square=4.244, p=0.039).
Continuous blood pressure measurement using the Finapres NOVA® in patients undergoing THA/TKA is feasible and can identify IOH irrespective of patient symptoms. Future studies need to explore monitoring approaches for physiotherapists to identify OI-type events and IOH during early postoperative mobilisation.
Physiotherapists need to consider preoperative orthostatic intolerance assessment to improve identification and management of orthostatic intolerance after THA/TKA.
Blood pressure
Arthroplasty
