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ORIGINAL ARTICLE   Free accessfree

Minerva Anestesiologica 2019 July;85(7):724-30

DOI: 10.23736/S0375-9393.18.12620-4


language: English

Discrimination and calibration properties of the hypotension probability indicator during cardiac and vascular surgery

Marco RANUCCI 1 , Luigi BARILE 1, Federico AMBROGI 2, Valeria PISTUDDI 1 Surgical and Clinical Outcome Research (SCORE) Group

1 Department of Cardiothoracic and Vascular Anesthesia and ICU, San Donato IRCCS Policlinic, Milan, Italy; 2 Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy

BACKGROUND: Hypotension during surgery is linked to postoperative complications. Recently, a new hemodynamic algorithm intended to predict hypotensive events (hypotension probability indicator [HPI]) has been developed. The aim of the present study is to test the discrimination and calibration properties of the HPI.
METHODS: The intraoperative files of 23 patients undergoing cardiac and major vascular surgery receiving the HPI-based hemodynamic monitoring were retrospectively investigated for prediction of hypotensive events (mean arterial pressure <65 mmHg). The HPI was available at 20 seconds intervals; the values of HPI five to seven minutes before a hypotensive event (HPI5-7) were tested for discrimination and calibration.
RESULTS: The HPI5-7 has a fair level of discrimination (area under the curve 0.768) and a poor calibration, due to overestimation of the hypotensive risk. At the observed prevalence, a cut-off value of 85% carries a sensitivity of 62.4% and a specificity of 77.7%, a negative predictive value (NPV) of 97.8% and a positive predictive value (PPV) of 12.6%; a value of 98% has a PPV of 64% and an NPV of 95.3%.
CONCLUSIONS: The HPI5-7 may offer some useful insights. Values ≤85% carry a clinically acceptable NPV for hypotensive events at the observed prevalence and may represent a “safe zone” during surgery. Values >85% do not carry enough PPV to trigger hemodynamic interventions, but represent a warning signal. Values >98% are highly suggesting a hypotensive event after 5-7 minutes. Further studies exploring the predictive ability of the HPI at different times are needed.

KEY WORDS: Arterial pressure; Hypotension; Surgery; Hemodynamic monitoring

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