(28 days)
Indicated for use in adults only.
The PhysioFlow Q-Link noninvasively measures cardiac output and other related cardiac parameters. These parameters include:
CI Cardiac Index
CO Cardiac Output
CTI Contractility Index
dZ / dt max Maximum value dZ / dt
EDV End Diastolic Volume
EF Ejection Fraction
HR Heart Rate
LCWI Left Cardiac Work Index
PEP Pre-Ejection Period
SV Stroke Volume
SVR Systemic Vascular Resistance
SVRI Systemic Vascular Resistance Index
TFI Thoracic Fluid Index
VET Ventricular Ejection Time
ZO Base Impedance
The PhysioFlow Q-Link is intended for use under the direct supervision of a licensed healthcare practitioner or personnel trained in its proper use within a hospital or facility providing healthcare.
The PhysioFlow Q-Link is a noninvasive, hemodynamic monitor that utilizes thoracic electrical bioimpedance technology to measure cardiac output and related cardiac parameters. It consists of a small, portable, lightweight electronic unit that attaches to the patient via a six lead, patient cable using commercially available silver/silver chloride skin electrodes. Monitor data is transmitted to a host computer running the PhysioFlow PF107 software. Communication to the host computer is via USB wired technology. The PhysioFlow PF107 software performs multiple tasks including signal processing and analysis, measured parameter computation, user interface display and control, measurement process control, event marker management, and output display/report generation. Available accessories include the patient and USB cables.
Here's an analysis of the provided text regarding the acceptance criteria and study for the PhysioFlow Q-Link device:
The provided document (a 510(k) summary) is very limited in its description of specific acceptance criteria and detailed study data. It primarily focuses on demonstrating substantial equivalence to a predicate device rather than providing a standalone validation study report for the new device.
Here's what can be extracted and what is explicitly not available from the text:
1. Table of Acceptance Criteria and Reported Device Performance
Based on the provided text, specific numerical acceptance criteria (e.g., accuracy +/- X%) and corresponding reported performance metrics are NOT available.
The document states:
"Design verification tests were performed on representative samples of the PhysioFlow Q-Link as a result of a comprehensive product development and risk management plan. All tests were verified to meet the pre-specified acceptance criteria."
This confirms that acceptance criteria exist internally, and the device met them, but the criteria themselves and the detailed performance results are not reported in this summary. The summary implies the acceptance criteria were met by comparison to the predicate device's performance, as the core argument for substantial equivalence.
2. Sample Size for the Test Set and Data Provenance
- Test Set Sample Size: Not explicitly stated. The document refers to "representative samples" for design verification tests, but the number of devices or subjects is not quantified.
- Data Provenance: Not explicitly stated. The nature of the tests ("design verification tests") suggests these were likely bench tests or in-house engineering evaluations rather than clinical studies with human subjects. The comparison is made to the previous device's performance, but no information is given about the original predicate device's data provenance either in this document.
3. Number of Experts Used to Establish Ground Truth for the Test Set and Their Qualifications
Not applicable/Not stated. This type of information (experts, their qualifications) is typically associated with studies involving human interpretation (e.g., radiologists reviewing images) or clinical trials requiring expert assessment. The "design verification tests" described here do not involve such expert review for ground truth establishment in the way typically seen in diagnostic AI/medical imaging devices. For a hemodynamic monitor, "ground truth" often refers to a reference standard (e.g., invasive cardiac catheterization) which is not mentioned here.
4. Adjudication Method for the Test Set
Not applicable/Not stated. As no expert review process for ground truth establishment is described, no adjudication method would be relevant.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
No, an MRMC comparative effectiveness study was not done.
This type of study is relevant for devices where human readers interpret data (e.g., images) and the AI aims to assist or replace that interpretation. The PhysioFlow Q-Link is a non-invasive hemodynamic monitor that provides objective physiological parameters. There is no human "reading" of the data in the sense that an MRMC study would apply. Therefore, no effect size for human readers improving with AI assistance is applicable or reported.
6. Standalone (Algorithm Only Without Human-in-the-Loop Performance) Study
Yes, in essence, a standalone performance assessment was done, but the details are minimal.
The "design verification tests" assess the device's ability to measure physiological parameters. Since it's a direct measurement device, its "standalone" performance is its fundamental operation. The summary does not describe a human-in-the-loop component in the measurement or calculation process that would necessitate a distinction between standalone and assisted performance. However, specific performance metrics for this standalone operation are not detailed in the summary.
7. Type of Ground Truth Used
Not explicitly stated, but inferred to be a reference standard or validated measurement method.
For a device measuring cardiac output and related parameters, the "ground truth" in a comprehensive validation study would typically be established using an invasive, gold-standard method (e.g., thermodilution via pulmonary artery catheter) or another well-validated non-invasive method. The summary does not specify how the "pre-specified acceptance criteria" were derived or validated, nor what reference method was used to establish the true values of the parameters being measured during the verification tests. Given the context of a 510(k) for a modification (Q-Link compared to Enduro PF-07), the implicit "ground truth" for the Q-Link's performance would be its agreement with the predicate device's measurements.
8. Sample Size for the Training Set
Not applicable/Not stated.
This device is not an AI/Machine Learning algorithm that undergoes a distinct "training" phase. It uses established thoracic electrical bioimpedance technology. Therefore, there is no "training set" in the context of an AI model. Its operational algorithms are based on physiological principles, not on learning from a dataset.
9. How the Ground Truth for the Training Set Was Established
Not applicable/Not stated.
As there is no training set for an AI/ML model, the concept of establishing ground truth for a training set does not apply. The device's underlying physical models and algorithms would have been developed using established physiological principles and prior research in bioimpedance.
Summary of what's provided for acceptance criteria and studies:
The provided 510(k) summary for the PhysioFlow Q-Link is brief and focuses on demonstrating substantial equivalence to its predicate device (PhysioFlow Enduro Model PF07) due to being a modification rather than a fundamentally new device. It asserts that "Design verification tests were performed on representative samples... All tests were verified to meet the pre-specified acceptance criteria." However, it does not provide the following crucial details:
- The specific numerical values for the "pre-specified acceptance criteria."
- Detailed quantitative performance data for the PhysioFlow Q-Link against those criteria.
- The sample size of items or subjects used in the verification tests.
- The method or reference standard used to establish "ground truth" for these tests, beyond implied comparison to the predicate.
- Any information regarding expert review, adjudication methods, or MRMC studies, as the device type does not involve human interpretation in that manner.
- Information about training sets or how ground truth was established for a training set, as it is not an AI/ML device relying on trained models.
Essentially, the document states that tests were done and criteria were met, but it does not reveal what those criteria or results were in this public summary. This level of detail is typically found in the full 510(k) submission or an internal design verification report, not usually in the summary provided.
§ 870.2770 Impedance plethysmograph.
(a)
Identification. An impedance plethysmograph is a device used to estimate peripheral blood flow by measuring electrical impedance changes in a region of the body such as the arms and legs.(b)
Classification. Class II (special controls). The device, when it is a body composition analyzer which is not intended to diagnose or treat any medical condition, is exempt from the premarket notification procedures in subpart E of part 807 of this chapter subject to the limitations in § 870.9.