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The Analytic for Hemodynamic Instability (AHI) software is intended for use by healthcare professionals managing in-hospital patients 18 years or older who are receiving continuous physiological monitoring with electrocardiography (ECG).

AHI provides a frequently undated binary output over time based on pattern analysis of a lead-II ECG waveform intended to describe a patient's hemodynamic status and indicate if a patient is showing signs of hemodynamic stability or instability. Signs of hemodynamic instability are defined as hypotension (systolic blood pressure <90 mmHg or mean arterial pressure (MAP) <70 mmHg) combined with tachycardia (heart rate ≥ 100 bpm).

The goal of this adjunctive monitoring method is to enable identification of patients who are showing signs of hemodynamic instability and to allow clinicians an opportunity to increase vigilance. This device is intended for adjunctive use with other physical vital sign parameters and patient information and is not intended to independently direct therapy.

Analytic for Hemodynamic Instability (AHI) is a software as a medical device (SaMD) that analyzes Lead-II ECG signals to identify patients who are showing signs of hemodynamic instability. Signs of hemodynamic instability are defined as low blood pressure (BP) and high heart rate (HR). The device processes 5 minutes of continuously recorded Lead II ECG data to determine the presence of a combination of HR ≥ 100 bpm and SBP < 90 mmHg/MAP < 70 mmHg within a 2-minute sliding window as shown in the figure below. The system normalizes input signals and assesses signal quality prior to data analysis.

Here's a breakdown of the acceptance criteria and the study proving the device meets them, based on the provided text:

1. Table of Acceptance Criteria and Reported Device Performance

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

• Test Set Sample Size: 222 patients contributed data for the primary analysis. These patients generated a large, unspecified number of "windows" of 5-minute ECG data, with (b) (4) windows containing valid paired data for comparison. Each patient contributed at most data from 150 windows.
• Data Provenance: Retrospective, single-center, observational study. The data was collected from November 26, 2019, through January 29, 2020, at the University of Michigan Medical Center. The data was "privately collected" and "IRB approved."

3. Number of Experts Used to Establish Ground Truth and Qualifications

The document does not explicitly state the number of experts used to establish the ground truth for the test set or their qualifications. Instead, the ground truth was established by:

• Continuous ECG monitoring.
• Continuous arterial line blood pressure monitoring.

The definition of hemodynamic instability used for ground truth (SBP < 90 mmHg or MAP < 70 mmHg combined with HR ≥ 100 bpm) is based on "medical literature references," implying consensus from existing clinical guidelines and research rather than real-time expert adjudication of each data point.

4. Adjudication Method for the Test Set

No formal human adjudication method (e.g., 2+1, 3+1) was used for the test set. The ground truth was established using objective physiological measurements (continuous ECG and continuous invasive arterial blood pressure).

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

No MRMC comparative effectiveness study was described. The study primarily evaluated the standalone performance of the AHI algorithm against objective physiological measurements. The device is intended for adjunctive use, meaning it assists human healthcare professionals, but the study did not quantify how much human readers improve with AI vs. without AI assistance.

6. Standalone Performance

Yes, a standalone performance study (algorithm only without human-in-the-loop performance) was conducted. The sensitivity and specificity reported (95.6% and 84.9% respectively) are for the AHI algorithm's performance in detecting hemodynamic instability compared to the established vital sign-based reference standard.

7. Type of Ground Truth Used

The ground truth used was objective physiological measurements and a vital-signs based definition of hemodynamic instability. Specifically:

• Heart Rate: Derived from continuous ECG monitoring. Ground truth for instability: HR ≥ 100 bpm.
• Blood Pressure: Derived from continuous invasive arterial line blood pressure monitoring. Ground truth for instability: SBP < 90 mmHg or MAP < 70 mmHg.

The combined ground truth for hemodynamic instability was defined as (SBP < 90 mmHg or MAP < 70 mmHg) combined with (heart rate ≥ 100 bpm). This definition is explicitly stated to be based on medical literature and widely accepted clinical criteria for hemodynamic distress.

8. Sample Size for the Training Set

The document does not specify the sample size used for the training set. It only mentions limitations based on "the limitations of the underlying dataset that AHI was trained on" but provides no details about this dataset.

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

The document does not provide details on how the ground truth for the training set was established. It only discusses the ground truth for the test set (clinical validation study), which was based on continuous ECG and arterial line blood pressure measurements.

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