BACKGROUND There is no consensus on how to define haemodynamic instability during general anaesthesia. Patients are often classified as stable or unstable based solely on blood pressure thresholds, disregarding the degree of instability. Vasoactive agents and volume therapy can directly influence classification but are usually not considered.
OBJECTIVE To develop and validate a scoring tool to quantify the overall degree of haemodynamic instability.
DESIGN Retrospective observational study.
SETTING University hospital.
PATIENTS The development cohort consisted of 50 patients undergoing high-risk surgery with a control group of 50 undergoing video-assisted thoracoscopic surgery. In the validation cohort, there were 153 high-risk surgery patients and 78 controls.
MAIN OUTCOME MEASURES The haemodynamic instability score (HI-score) was calculated as a weighted continuous measure ranging from 0 to 160 points, intended to reflect deviations of blood pressure and heart rate from predefined thresholds, and infusion rates of vasoactive agents and fluids. Thresholds were first determined in a development cohort and subsequently tested in a validation cohort. Results are presented as median [interquartile range].
RESULTS In the validation cohort the HI-score was 59 [37 to 96] in the high-risk surgery group compared with 44 [24 to 58] in the control group (P
CONCLUSION We developed the HI-score and demonstrated that it can appropriately quantify the degree of intra-operative haemodynamic instability. The HI-score provides a clinical tool which, after further external validation, may have future applications in both patient management and clinical research.