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The APPRAISE-HRI is a mobile health app intended to provide a means for military healthcare providers to screen U.S. Service members for hemorrhage risk after a physically traumatic event and stratify casualties who need immediate attention and emergency evacuation from those who are injured but may not be at risk for hemorrhage.

The APPRAISE-HRI is not intended to diagnose or direct treatment. Rather, it is intended to provide situational awareness and inform clinical management of potentially hemorrhagic casualties by identifying those at the greatest risk of hemorrhage.

The Automated Processing of the Physiological Registry for Assessment of Injury Severity (APPRAISE)-Hemorrhage Risk Index (HRI) is an Android application developed by the U.S. Army Medical Research and Development Command (USAMRDC) that uses vital-sign data collected from a trauma patient to provide a risk score that stratifies the patient's risk of hemorrhage. When the application runs, heart rate (HR), systolic blood pressure (SBP), and diastolic blood pressure (DBP) vital-sign data are collected from an external monitor [currently only the ZOLL Propaq M (K202375) is supported]. The ZOLL Propaq M monitor connects via Bluetooth with the Android platform running the APPRAISE-HRI application. The APPRAISE-HRI application continuously pulls data from the ZOLL Propaq M monitor to gather the required vital signs (HR, SBP, and DBP) and then runs the hemorrhage risk stratification algorithm to generate an output every one minute.

Once the vital-sign data from the ZOLL Propaq M monitor are transferred, the APPRAISE-HRI provides a stratification of hemorrhage into three Risk Level categories: Low (I), Average (II), or High (II). The APPRAISE-HRI application continuously displays both the input vital signs (HR, SBP, and DBP) and the Risk Level score to the caregiver to provide situational awareness and to inform clinical management of potentially hemorrhagic casualties by identifying those at the greatest risk of hemorrhage.

Here's a summary of the acceptance criteria and study details for the APPRAISE-HRI device, based on the provided document:

Acceptance Criteria and Device Performance

Note: The acceptance criteria were success criteria focusing on the device effectively and consistently differentiating between HRI Levels I, II, and III, and the ground truth for trauma patients tracking consistently with the algorithm results. The specific numerical targets for the Likelihood Ratios are derived from the interpretation in the document where "at least five times less likely," "almost as likely," and "nearly seven times more likely" were stated.

Study Details

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The AHI System is intended for use by healthcare professionals managing patients 18 years or older who are receiving continuous physiological monitoring with electrocardiography (ECG) in hospitals.

AHI provides a frequently updated 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 (HI) are defined as hypotension (systolic blood pressure <90 mmHg or mean arterial pressure (MAP) <70 mmHq) combined with tachycardia (heart rate ≥ 100 bpm).

AHI-PI provides the clinician with physiological insight into a patient's likelihood of a future episode of HI. An episode of HI is defined as 10 continuous minutes or more where HI is present.

The goal of this adjunctive monitoring method is to enable identification of patients who are showing HI or are likely to experience a future episode of HI, 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.

The AHI System is a multiparameter system designed to meet clinicians' need to identify patient hemodynamic status and predict patient hemodynamic instability episodes using two analytics:1. Analytic for Hemodynamic Instability (AHI): Utilizing data from a single existing lead of a non-invasive electrocardiograph (ECG), AH analyzes heart rate variability (HRV) and ECG morphology features to rapidly detect signs of hemodynamic stability and categorize each window of data as either "AHI Stable" or "AHI Unstable." Time trending of AHI outputs is also provided.

2. Analytic for Hemodynamic Instability Predictive Indicator (AH-P); Utilizing AH outputs from up to the most recent 30 minutes of EG data, AH-PI indicates the likelihood of a future episode of hemodynamic instability, defined as ten continuous minutes or more where signs of hemodynamic instability are present.

The provided text details the FDA clearance for the AHI System (v 2.2.0) and references a previous version (K212219) as the predicate device. However, the document primarily focuses on regulatory approval and equivalence, not on a detailed study proving the device meets specific acceptance criteria with performance metrics, sample sizes, expert qualifications, or ground truth establishment.

Therefore, many of the requested details about the study proving the device meets acceptance criteria are not present in the provided text. The text only vaguely refers to "Software: Software verification and validation testing were conducted and documentation was provided... Testing was conducted to ensure the AHI System works as designed." This is insufficient to populate the requested table and further study details.

Based on the provided text, here's what can be extracted and what is missing:

1. Table of Acceptance Criteria and Reported Device Performance

The provided text does not include a table of acceptance criteria or reported device performance metrics such as sensitivity, specificity, or AUC for the AHI System (v 2.2.0) or its predicate. It only states the device "works as designed" following software V&V.

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

The provided text does not specify the sample size used for any test set or the provenance (e.g., country of origin, retrospective/prospective) of the data.

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

The provided text does not mention the number or qualifications of experts used to establish ground truth for any test set.

4. Adjudication Method for the Test Set

The provided text does not describe any adjudication method (e.g., 2+1, 3+1, none) for a test set.

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

The provided text does not indicate that an MRMC comparative effectiveness study was done, nor does it provide any effect size for human reader improvement with or without AI assistance.

6. Standalone Performance Study

While the device's function (AHI and AHI-PI) is described as "pattern analysis of a lead-II ECG waveform" to indicate hemodynamic status and predict instability, the document does not provide the results of a standalone (algorithm only) performance study with specific metrics. It states "Testing was conducted to ensure the AHI System works as designed," which is a high-level statement without data.

7. Type of Ground Truth Used for the Test Set

The "Signs of hemodynamic instability (HI)" are defined within the Indications for Use as "hypotension (systolic blood pressure <90 mmHg or mean arterial pressure (MAP) <70 mmHg) combined with tachycardia (heart rate ≥ 100 bpm)." This operational definition of HI serves as the clinical definition/outcome data that the AHI system aims to detect or predict. It's likely this definition would form the basis of the ground truth if a study were conducted, but the document does not explicitly state how this ground truth was used or established in a specific test set or if it was verified by experts.

8. Sample Size for the Training Set

The provided text does not specify the sample size for any training set used for the algorithm.

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

The provided text does not explain how the ground truth for any training set was established.

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The AHI System is intended for use by healthcare professionals managing patients 18 years or older who are receiving continuous physiological monitoring with electrocardiography (ECG) in hospitals.

AHI provides a frequently updated 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 (HI) are defined as hypotension (systolic blood pressure <90 mmHg or mean arterial pressure (MAP) <70 mmHg) combined with tachycardia (heart rate ≥ 100 bpm).

AHI-PI provides the clinician with physiological insight into a patient's likelihood of a future episode of HI. An episode of HI is defined as 10 continuous minutes or more where HI is present.

The goal of this adjunctive monitoring method is to enable identification of patients who are likely to experience a future episode of HI, 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.

The AHI System is a multiparameter system designed to meet clinicians' need to identify patient hemodynamic status and predict patient hemodynamic instability episodes using two analytics:

1. Analytic for Hemodynamic Instability (AHI) (as granted in DEN200022): Utilizing data from a single existing lead of a non-invasive electrocardiograph (ECG), AHI analyzes heart rate variability (HRV) and ECG morphology features to rapidly detect signs of hemodynamic stability or instability and categorize each window of data as either "AHI Stable" or "AHI Unstable." Time trending of AHI outputs is also provided.

2. Analytic for Hemodynamic Instability Predictive Indicator (AHI-PI): Utilizing AHI outputs from up to the most recent 30 minutes of ECG data, AHI-PI indicates the likelihood of a future episode of hemodynamic instability, defined as ten continuous minutes or more where signs of hemodynamic instability are present.

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

• Sample Size: 65,969 "windows" (data points representing a period of time for which an AHI-PI indicator was generated). The exact number of patients is not explicitly stated, but the note mentions: "The unit of analysis here is at the windows level and not the patient level." The study used bootstrapping to account for multiple measurements per subject.
• Data Provenance: Prospectively collected from consecutive patients at Michigan Medicine. This indicates the data is from the United States and is prospective.
• Targeted Patient Population: Hospitalized patients 18 years or older who are receiving continuous physiological monitoring with electrocardiography (ECG) and are not contraindicated. Due to study design considerations, the primary study population was limited to patients who were invasively monitored with an arterial line.

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

• The document does not mention the use of experts to establish the ground truth for the test set.

4. Adjudication Method for the Test Set

• The document does not mention an adjudication method for the test set.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was done, If so, what was the effect size of how much human readers improve with AI vs without AI assistance

• No MRMC comparative effectiveness study is mentioned for the AHI-PI system. The study focuses on the standalone performance of the AHI-PI algorithm. The device is intended for "adjunctive use" meaning it supports human healthcare professionals, but specific studies on human improvement with AI assistance are not described here.

6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) was done

• Yes, a standalone performance study was done for the AHI-PI. The reported data in the table directly reflects the algorithm's ability to predict hemodynamic instability without human intervention in the prediction process itself. The study compared AHI-PI outputs to a vital signs reference standard.

7. The Type of Ground Truth Used (expert consensus, pathology, outcomes data, etc.)

• Outcomes Data/Physiological Reference Standard: The ground truth for hemodynamic instability (HI) was defined using a "hemodynamic vital signs reference standard" based on continuous vital signs:
  • Hypotension (systolic blood pressure <90 mmHg or mean arterial pressure (MAP) <70 mmHg) combined with
  • Tachycardia (heart rate ≥ 100 bpm)
• An "episode of HI" was further defined as 10 continuous minutes or more where these HI conditions are present.

8. The Sample Size for the Training Set

• The document does not specify the sample size used for the training set. It only describes the validation data.

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

• The document does not specify how the ground truth for the training set was established. It only describes the ground truth for the validation set.

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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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