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The Cardiac Power Index during Abdominal Open Aortic Surgery: Intraoperative Insights into the Cardiac Performance-A
Fulvio Nisi1, Enrico Giustiniano1, Massimo Meco2
1Department of Anesthesia, Intensive Care Unit and Pain Therapy, IRCCS Humanitas Clinical and Research Center, Via Manzoni 56, 20089 Milan, Italy.
Insights
The Cardiac Power Index (CPI) significantly increases after aortic unclamping during open aortic surgery, indicating its role in monitoring heart function. Lower baseline CPI may predict the need for inotropic support in these patients.
Area of Science:
- Cardiology
- Cardiovascular Surgery
- Hemodynamics
Background:
- The Cardiac Power Index (CPI) quantifies heart energy output and is linked to cardiogenic shock mortality.
- Open aortic surgery involves significant hemodynamic shifts due to aortic clamping and unclamping, potentially impairing cardiac function.
- Understanding these hemodynamic changes is crucial for patient outcomes.
Purpose of the Study:
- To investigate the impact of aortic cross-clamping (Ao-XC) and unclamping (Ao-UC) on the Cardiac Power Index (CPI) during open aortic surgery.
- To assess secondary hemodynamic parameters including cardiac index (CI), mean arterial pressure (MAP), heart rate, and lactate levels.
- To explore the potential of CPI as a real-time indicator of cardiac performance and impairment during surgery.
Main Methods:
- Retrospective analysis of 67 patients undergoing open surgical aortic repair.
- Intra-operative hemodynamic monitoring using the EV1000-FloTrac System™.
- Calculation of CPI as (CI × MAP)/451 and analysis of variations during basal, Ao-XC, and Ao-UC phases.
Main Results:
- CPI showed a significant increase after aortic unclamping (basal: 0.39 ± 0.1 W/m², after Ao-UC: 0.44 ± 0.2 W/m², p < 0.05).
- Cardiac index (CI) varied significantly during both clamping and unclamping (p < 0.0001), while MAP and heart rate remained stable.
- Patients requiring inotropic support post-clamping had a lower baseline CPI (0.31 ± 0.11 W/m²) compared to the general cohort.
Conclusions:
- CPI effectively reflects cardiac function adaptation to hemodynamic changes during aortic cross-clamping and unclamping.
- CPI offers a minimally invasive method for real-time cardiac performance assessment and prediction of intraoperative cardiac impairment.
- CPI may serve as a valuable tool analogous to ventriculo-arterial coupling parameters in surgical settings.
Abstract:
Background: The Cardiac Power Index (CPI) measures the rate of energy output generated by the heart and correlates this with in-hospital mortality due to cardiogenic shock. In open aortic surgery, both aortic clamping and unclamping expose the heart to abrupt variations of the left ventricle afterload, preload, and contractility, with possible hemodynamic impairment. We investigated how aortic-cross clamping (Ao-XC) and unclamping (Ao-UC) procedures affect the CPI during open aortic surgery. Methods: We retrospectively analyzed our surgical database of 67 patients submitted to open surgical aortic repair at Humanitas Research Hospital, Milan. Patients were monitored by an EV1000-FloTrac SystemTM (Edwards Lifescience, Irvine, CA, USA) beyond the standard intra-operative hemodynamic monitoring. The primary outcome was the variation of basal CPI after aortic clamping and unclamping. Secondary outcomes were variations of the cardiac index (CI), mean arterial pressure (MAP), heart rate, and lactate during aortic clamping and after unclamping. The CPI was computed as: (CI × MAP)/451. Results: The CPI changed significantly after aortic unclamping. CPI: basal = 0.39 ± 0.1 W/m2, after Ao-XC = 0.39 ± 0.1 W/m2, and after Ao-UC = 0.44 ± 0.2 W/m2, p < 0.05. The CI changed during both cross-clamping and unclamping (p < 0.0001), whilst the MAP and heart rate did not during any phase of the surgery. Five subjects (8.3%) needed inotropic support after cross-clamping. Their basal CPI was lower than the general population: 0.31 ± 0.11 W/m2 vs. 0.39 ± 0.1 W/m2. Conclusions: The CPI describes the adaptation of the cardiac function to the changes in preload, contractility, and afterload occurring during aortic cross-clamping and unclamping. It may be used to explore the cardiac performance in real-time and predict cardiac impairment in the intraoperative period in a minimally invasive way, similar to ventriculo-arterial coupling parameters.
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