Methods and apparatuses for assessment and management of hemodynamic status
Inventors
Robinson, Mark Ries • Allen, Elena A
Assignees
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Publication Number
US-11363956-B2
Publication Date
2022-06-21
Expiration Date
Abstract
Embodiments of the present invention provide reliable, convenient, and cost-effective methods and apparatuses to determine the hemodynamic status of the patent. The methods and apparatuses provide for the noninvasive determine of hemodynamic status by using systematic perturbations of venous return or trend observation over time. Embodiments do not require invasive pressure monitoring or the use of ventilator but instead can be an entirely noninvasive system.
Core Innovation
The invention provides a method for determining the volume status of a patient by causing the patient to perform a breathing protocol through a resistance breathing device having one or more flow-independent pressure valves. The device allows inhalation airflow after inhalation pressure exceeds a first inhale pressure threshold and allows exhalation airflow after exhalation pressure exceeds a first exhale pressure threshold. While the patient performs the breathing protocol, the method noninvasively determines one or more time intervals within the patient's cardiac cycle over a first plurality of heartbeats, where each time interval corresponds to the time between predetermined events in the systolic phase of the cardiac cycle.
The method determines a first variance of the systolic-phase time intervals over the first plurality of heartbeats and determines intravascular volume status from the first variance. The approach integrates the controlled breathing perturbation with cardiac-cycle systolic time-interval variability computed from noninvasive measurements, to estimate fluid-related volume state through measured changes in cardiac timing.
According to the disclosed implementation, the time intervals can be determined using one or more of an electrocardiogram, a photoplethysmogram, and a phonocardiogram. The systolic-phase time intervals are selected from named interval types including PAT, PEP, LVET, PTT, EMAT, and ICT, and the variance-based mapping is used to derive volume status. The document also describes noninvasive hemodynamic assessment in which venous return is perturbed by controlled breathing and/or positional changes, followed by phase-aware processing that separates inhale and exhale and uses transition-based metrics.
Claims Coverage
The patent family includes one independent method claim focused on deriving intravascular volume status from the variance of noninvasively measured systolic-phase cardiac-cycle time intervals during a controlled breathing protocol using a resistance breathing device with flow-independent pressure valves. In total, the independent claim includes multiple inventive features that dependent claims further delimit.
Flow-independent valve resistance breathing protocol
Causing a patient to perform a breathing protocol through a resistance breathing device having one or more flow-independent pressure valves that allow inhalation airflow after inhalation pressure exceeds a predetermined first inhale pressure threshold and allow exhalation airflow after exhalation pressure exceeds a predetermined first exhale pressure threshold.
Noninvasive systolic-phase time-interval determination across heartbeats
While the patient is performing the breathing protocol, noninvasively determining one or more time intervals within the patient's cardiac cycle over a first plurality of heartbeats, where each time interval corresponds to the time between predetermined events in the systolic phase of the cardiac cycle.
Variance of systolic-phase cardiac time intervals
Determining a first variance of the time intervals over the first plurality of heartbeats.
Deriving intravascular volume status from interval variance
Determining the intravascular volume status of the patient from the first variance.
Noninvasive sensing modalities for time intervals
Determining the time intervals using at least one of an electrocardiogram, a photoplethysmogram, or a phonocardiogram.
Selected systolic time-interval types
Selecting the one or more time intervals from PAT, PEP, LVET, PTT, EMAT, and ICT.
Repeated measurement with second inhale/exhale thresholds
Repeating the method using a breathing protocol comprising a second plurality of heartbeats, determining a second heartbeat-interval variance, and determining the patient's volume status from both the first and second variances.
Increased second pressure thresholds
Setting the second inhale and/or exhale pressure threshold(s) greater than the corresponding first inhale and exhale pressure threshold(s).
Minimum exhalation pressure threshold constraint
Limiting the method such that the exhale pressure threshold is at least 5 cm H2O.
Overall, the claim set centers on perturbed breathing using a flow-independent valve resistance device, noninvasive determination of systolic-phase cardiac-cycle time intervals over a plurality of heartbeats, computing a variance of those intervals, and deriving intravascular volume status from that variance, with dependent claims further specifying measurement modalities, allowable interval types, repeated threshold configurations, and minimum threshold constraints.
Stated Advantages
Enables determination of intravascular volume status from noninvasive measurement of systolic-phase cardiac-cycle time-interval variance during a controlled breathing protocol.
Detects earlier hemodynamic congestion than clinical signs.
Improves sensitivity compared to conventional variance processing as described in demonstration datasets.
Documented Applications
Hemodynamic assessment in contexts including dialysis.
Hemodynamic assessment using lower body negative pressure (LBNP).
Hemodynamic assessment using positional changes.
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