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The Edwards Lifesciences Acumen Hypotension Prediction Index (HPI) feature provides the clinician with physiological insight into a patient's likelihood of future hypotensive events (defined as mean arterial pressure < 65 mmHg for at least one minute in duration) and the associated hemodynamics. The Acumen HPI feature is intended for use in operating room (OR) patients receiving advanced hemodynamic monitoring. The Acumen HPI feature is considered to be additional quantitative information regarding the patient's physiological condition for reference only and no therapeutic decisions should be made based solely on the Hypotension Prediction Index (HPI) parameter.

The Acumen Hypotension Prediction Index Feature ("the device") consists of software running on the Edwards Lifesciences EV1000 Platform (previously cleared under K100709, K110597, K131892. K140312, and K160552) paired with the FloTrac IQ extravascular blood pressure transducer (K152980) and a radial arterial catheter. The device includes the Hypotension Prediction Index (HPI), the Dynamic Arterial Elastance Parameter (Eagyn), the Left Ventricular Contractility Parameter (dP/dt), and additional graphical user interface features.

HPI is an index related to the likelihood of a patient experiencing a hypotensive event (defined as mean arterial pressure (MAP) <65 mmHg for one minute in duration) within fifteen minutes, where zero (0) indicates low likelihood and one hundred (100) indicates high likelihood. The EV1000 Platform initiates a high priority alarm (red) when HPI exceeds 85. The Hypotension Prediction Index, HPI, should not be used exclusively to treat the patients. A review of the patient's hemodynamics is recommended prior to initiating treatment.

HPI is not defined by a single equation. HPI uses features extracted from FloTrac IQ measurements, some compared to an initial base value determined over the first 10 minutes of the patient monitoring session, to a data-driven model developed from retrospective analysis of an arterial waveform database collected from ICU and OR patients containing annotated hypotensive (defined as MAP <65 mmHG for at least 1 minute) and non-hypotensive events.

Eadm is a physiologic parameter related to left ventricular afterload relative to the left ventricular elastance. It is calculated by dividing Pulse Pressure Variation (PPV) by Stroke Volume Variation (SVV), or Eadyn = PPV/SVV.

dP/dt is a physiologic parameter related to the change in contractility of the left ventricle. It is calculated as the maximal first derivative of the arterial pressure waveform with respect to time.

Additional graphical user interface features include the HPI High Alert Popup, which displays when HPI exceeds 85 for two consecutive 20-second updates or reaches 100 at any time, and the HPI Secondary Screen, which consolidates hemodynamic parameters into a single screen.

1. Table of Acceptance Criteria and Reported Device Performance

Note: The document does not explicitly state numerical acceptance criteria for sensitivity, specificity, and AUC. However, the reported performance metrics from the clinical validation studies demonstrate a level of accuracy deemed acceptable by the FDA for de novo classification. The high specificities and AUC values, along with the detailed performance table for different HPI ranges, suggest that the device's ability to predict hypotension within the 15-minute timeframe was considered sufficient. The acceptance criteria for usability testing (at least 80% of participants agree or strongly agree) are explicitly stated in the Usability Testing section.

2. Sample Size Used for the Test Set and Data Provenance

The "test set" for the HPI algorithm's performance evaluation was derived from two retrospective patient databases:

• First Database (Edwards Lifesciences):
  • Sample Size: 52 subjects (OR patients)
  • Data Provenance: Global clinical sites, collected via prospective, IRB/EC approved clinical protocols with informed consent for each patient. (Retrospective analysis of prospectively collected data).
• Second Database (University Hospital):
  • Sample Size: 204 subjects (OR patients)
  • Data Provenance: From a university hospital, includes OR patients. (Retrospective analysis of an arterial waveform database).

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts

The document does not specify the "number of experts" or their "qualifications" used to establish the ground truth for the test set.

Instead, the ground truth for hypotensive events was defined objectively: "mean arterial pressure (MAP) < 65 mmHg for at least one minute in duration." The databases used for validation contained "annotated hypotensive (defined as MAP <65 mmHG for at least 1 minute) and non-hypotensive events." This implies that the ground truth was established based on these objective physiological measurements rather than expert consensus on individual cases.

4. Adjudication Method for the Test Set

Not applicable. The ground truth was based on objective physiological measurements (MAP < 65 mmHg for at least one minute), not expert adjudication requiring consensus or multiple readings.

5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study

No, a multi-reader multi-case (MRMC) comparative effectiveness study was not reported. The device is intended as an adjunctive predictive cardiovascular indicator, providing quantitative information, not as a diagnostic aid that directly replaces or assists human readers in interpreting complex images or clinical scenarios requiring reader performance comparison. The study focused on the algorithm's standalone performance.

6. Standalone Performance Study (Algorithm Only Without Human-in-the-Loop Performance)

Yes, a standalone performance study was done. The reported sensitivity, specificity, and AUC values (83.7%, 99.8%, 0.95 for N=52 study; 65.8%, 99.4%, 0.88 for N=204 study) represent the performance of the HPI algorithm itself in predicting hypotensive events from extracted FloTrac IQ measurements. The device is explicitly stated as an "adjunctive predictive cardiovascular indicator" and "not intended to independently direct therapy," but its performance metrics are presented in a standalone context.

7. Type of Ground Truth Used

The type of ground truth used was objective physiological outcomes data, specifically:

• Hypotensive event: Defined as mean arterial pressure (MAP) < 65 mmHg for at least one minute in duration.

This objective definition was used to annotate the events in the retrospective arterial waveform databases.

8. Sample Size for the Training Set

The document states: "HPI uses features extracted from FloTrac IQ measurements... to a data-driven model developed from retrospective analysis of an arterial waveform database collected from ICU and OR patients containing annotated hypotensive... and non-hypotensive events."

However, it does not explicitly state the sample size of the training set. It only mentions that the model was "developed from retrospective analysis" of the overall databases, and the reported clinical validation results (N=52 and N=204 studies) were presumably used as test sets to evaluate the performance of this already developed model. The training and test sets might have been derived from the same larger pool of data.

9. How the Ground Truth for the Training Set Was Established

The ground truth for the model development (training) "was established" in the same manner as the validation ground truth:

• Hypotensive event: Defined as mean arterial pressure (MAP) < 65 mmHg for at least one minute in duration.

The training data came from "an arterial waveform database collected from ICU and OR patients containing annotated hypotensive (defined as MAP <65 mmHG for at least 1 minute) and non-hypotensive events." This indicates that the ground truth for both training and testing was based on these objective, physiologically defined annotations of hypotensive events.

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