{
  "@context": "https://uofa.net/spec/context/v0.9.jsonld",
  "id": "https://uofa.net/morrison-v09/cou1",
  "type": "UnitOfAssurance",
  "conformsToProfile": "https://uofa.net/vocab#ProfileComplete",
  "name": "Morrison COU1 — CPB hemolysis credibility assessment",
  "description": "V&V 40 credibility assessment for CFD hemolysis prediction of the FDA generic centrifugal blood pump under cardiopulmonary bypass (CPB) conditions. COU1 evaluates whether the computational model can identify worst-case hemolysis operating conditions for a Class II CPB device at Model Risk Level 2. Full 13-factor assessment: 7 factors assessed (all meeting required levels), 6 factors not assessed (acceptable at MRL 2).",
  "bindsRequirement": "https://uofa.net/morrison-v09/req/hemolysis-safety",
  "bindsClaim": "https://uofa.net/morrison-v09/claim/cou1-hemolysis-adequacy",
  "bindsModel": "https://uofa.net/morrison-v09/model/ansys-cfx-15-sst-kw",
  "bindsDataset": [
    "https://uofa.net/morrison-v09/data/piv-velocity",
    "https://uofa.net/morrison-v09/data/hemolysis-invitro"
  ],
  "hasContextOfUse": {
    "id": "https://uofa.net/morrison-v09/cou/cou1-cpb",
    "type": "ContextOfUse",
    "name": "COU1: Cardiopulmonary bypass use (Class II)",
    "description": "A CFD model is used to evaluate the sensitivity of pump-induced hemolysis to variations in component dimensions for a centrifugal blood pump used during cardiopulmonary bypass surgery. Model influence is MEDIUM (testing confirms results); decision consequence is HIGH (incorrect tolerance decision could impact clinical hemolysis levels). Model Risk Level 2.",
    "intendedUse": "Use CFD to identify worst-case operating conditions for hemolysis across 5 flow-speed combinations for a Class II CPB device. Results compared against predicate device hemolysis using relative hemolysis index (RH < 1 acceptance criterion).",
    "deviceClass": "Class II",
    "modelInfluence": "Medium",
    "decisionConsequence": "High"
  },
  "hasValidationResult": [
    "https://uofa.net/morrison-v09/validation/mesh-convergence",
    "https://uofa.net/morrison-v09/validation/piv-velocity-comparison",
    "https://uofa.net/morrison-v09/validation/hemolysis-comparison-cou1"
  ],
  "wasDerivedFrom": "https://doi.org/10.1115/1.4043024",
  "wasAttributedTo": "https://uofa.net/org/FDA-CDRH",
  "generatedAtTime": "2019-02-01T00:00:00Z",
  "hash": "sha256:0000000000000000000000000000000000000000000000000000000000000000",
  "signature": "ed25519:00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000",
  "signatureAlg": "ed25519",
  "canonicalizationAlg": "json-sortkeys/v1",
  "hasCredibilityFactor": [
    {
      "type": "CredibilityFactor",
      "factorType": "Software quality assurance",
      "requiredLevel": 1,
      "achievedLevel": 1,
      "factorStatus": "assessed",
      "acceptanceCriteria": "Goal (a): commercial CFD solver commonly used by industry and academia for blood pump evaluation. No major SQA issues previously reported. User may reference SQA documentation provided by code developer. [Morrison Table 3, COU1]",
      "rationale": "ANSYS CFX v15.0 is widely used for centrifugal blood pump CFD. SQA documentation available from vendor. Low model influence for COU1 justifies minimal SQA rigor.",
      "factorStandard": "ASME-VV40-2018"
    },
    {
      "type": "CredibilityFactor",
      "factorType": "Numerical code verification",
      "requiredLevel": 3,
      "achievedLevel": 3,
      "factorStatus": "assessed",
      "acceptanceCriteria": "Goal (c): numerical solution compared to an accurate benchmark analytical solution. Comparison against Hariharan et al. verification benchmarks for the Eulerian power-law hemolysis model is mandatory due to previously reported user implementation errors. [Morrison Table 3, COU1]",
      "rationale": "Eulerian HI model benchmarked against analytical solutions from Hariharan et al. (2015). Previous literature reported user error in implementing Eulerian hemolysis models, making benchmark comparison necessary.",
      "factorStandard": "ASME-VV40-2018"
    },
    {
      "type": "CredibilityFactor",
      "factorType": "Discretization error",
      "requiredLevel": 3,
      "achievedLevel": 3,
      "factorStatus": "assessed",
      "acceptanceCriteria": "Goal (c): grid convergence performed, conservation equation balances checked, no estimation of discretization error required. Grid convergence essential because hemolysis occurs in high shear regions and shear stress estimations are grid-sensitive. [Morrison Table 3, COU1]",
      "rationale": "Three mesh densities evaluated. Velocity and hemolysis index predictions changed by less than 1% with mesh refinement. Conservation equation balances verified.",
      "factorStandard": "ASME-VV40-2018"
    },
    {
      "type": "CredibilityFactor",
      "factorType": "Test conditions",
      "requiredLevel": 2,
      "achievedLevel": 2,
      "factorStatus": "assessed",
      "acceptanceCriteria": "Goal (b): key characteristics of test conditions measured — flow rate, impeller rotational speed, viscosity and density of blood or blood-analog fluid. Experiments repeated five times per operating condition to quantify uncertainties. [Morrison Table 4, COU1]",
      "rationale": "Flow rate measured via calibrated ultrasound flow meter. Impeller speed measured via tachometer. Fluid viscosity and density measured before every experiment via rheometer and densitometer. Five repeats per condition.",
      "factorStandard": "ASME-VV40-2018"
    },
    {
      "type": "CredibilityFactor",
      "factorType": "Output comparison",
      "requiredLevel": 2,
      "achievedLevel": 2,
      "factorStatus": "assessed",
      "acceptanceCriteria": "Quantity goal (b): two outputs compared — velocity and relative hemolysis (RH). Rigor goal (c): experimental uncertainty quantified and used in comparison; CFD uncertainty quantification not required for COU1 (model influence Low). Agreement goal (b): difference between CFD and experimental RH small relative to safety threshold (RH < 1). [Morrison Table 4, COU1]",
      "rationale": "Velocity comparison: CFD peak velocity matched PIV data within ~15%. Hemolysis comparison: CFD predicted RH fivefold lower than safety threshold at validation point, so ~40% model error still acceptable.",
      "factorStandard": "ASME-VV40-2018"
    },
    {
      "type": "CredibilityFactor",
      "factorType": "Relevance of the quantities of interest",
      "requiredLevel": 2,
      "achievedLevel": 2,
      "factorStatus": "assessed",
      "acceptanceCriteria": "Hemolysis is directly applicable to the question of interest. Relative hemolysis (RH) is an acceptable validation metric — measures hemolysis relative to a predicate device threshold. [Morrison Results, COU1 Applicability]",
      "rationale": "RH compares subject device hemolysis to commercially available predicate device. RH < 1 means subject device causes less hemolysis than predicate. Directly addresses the question of interest.",
      "factorStandard": "ASME-VV40-2018"
    },
    {
      "type": "CredibilityFactor",
      "factorType": "Relevance of the validation activities to the COU",
      "requiredLevel": 2,
      "achievedLevel": 2,
      "factorStatus": "assessed",
      "acceptanceCriteria": "Goal (b): partial overlap between validation points and COU conditions. Since model influence is Low (COU1), partial overlap is acceptable — validation point (condition 1) lies within the COU operating range. [Morrison Table 4, COU1]",
      "rationale": "Validation at condition 1 (2.5 lpm, 2500 rpm) lies within the COU operating range. Model used to identify worst-case conditions, which are then confirmed by in vitro testing. Partial overlap sufficient because model influence is Low.",
      "factorStandard": "ASME-VV40-2018"
    },
    {
      "id": "https://uofa.net/morrison-v09/cou1/factor/numerical-solver-error",
      "type": "CredibilityFactor",
      "factorType": "Numerical solver error",
      "factorStatus": "not-assessed",
      "factorStandard": "ASME-VV40-2018"
    },
    {
      "id": "https://uofa.net/morrison-v09/cou1/factor/use-error",
      "type": "CredibilityFactor",
      "factorType": "Use error",
      "factorStatus": "not-assessed",
      "factorStandard": "ASME-VV40-2018"
    },
    {
      "id": "https://uofa.net/morrison-v09/cou1/factor/model-form",
      "type": "CredibilityFactor",
      "factorType": "Model form",
      "factorStatus": "not-assessed",
      "factorStandard": "ASME-VV40-2018"
    },
    {
      "id": "https://uofa.net/morrison-v09/cou1/factor/model-inputs",
      "type": "CredibilityFactor",
      "factorType": "Model inputs",
      "factorStatus": "not-assessed",
      "factorStandard": "ASME-VV40-2018"
    },
    {
      "id": "https://uofa.net/morrison-v09/cou1/factor/test-samples",
      "type": "CredibilityFactor",
      "factorType": "Test samples",
      "factorStatus": "not-assessed",
      "factorStandard": "ASME-VV40-2018"
    },
    {
      "id": "https://uofa.net/morrison-v09/cou1/factor/equivalency-of-input-parameters",
      "type": "CredibilityFactor",
      "factorType": "Equivalency of input parameters",
      "factorStatus": "not-assessed",
      "factorStandard": "ASME-VV40-2018"
    }
  ],
  "hasWeakener": [],
  "hasDecisionRecord": {
    "id": "https://uofa.net/morrison-v09/decision/cou1-overall",
    "type": "DecisionRecord",
    "actor": "https://uofa.net/org/FDA-CDRH",
    "role": "Credibility assessment team",
    "outcome": "Accepted",
    "rationale": "Model deemed sufficiently credible for COU1. All verification goals achieved at or above target gradation levels. Validation comparison at all 5 operating conditions shows hemolysis index below CPB predicate threshold (RH < 1). No formal CFD uncertainty quantification performed for COU1 (addressed by W-AL-01 weakener).",
    "decidedAt": "2019-02-01T00:00:00Z",
    "decisionProvenance": "extracted",
    "decisionAnchor": {
      "type": "SourceAnchor",
      "anchorLocator": "archive://morrison/source/decision_rationale_cou1.pdf",
      "anchorSha256": "sha256:01190eb07629faf0b83aa29c3dd2829d599137f70f1f9446c87c1970bb7eb211"
    }
  },
  "assuranceLevel": "Medium",
  "criteriaSet": "https://uofa.net/criteria/ASME-VV40-2018",
  "credibilityIndex": {
    "@value": "1.00",
    "@type": "xsd:decimal"
  },
  "traceCompleteness": {
    "@value": "0.71",
    "@type": "xsd:decimal"
  },
  "verificationCoverage": {
    "@value": "0.60",
    "@type": "xsd:decimal"
  },
  "validationCoverage": {
    "@value": "0.50",
    "@type": "xsd:decimal"
  },
  "uncertaintyCIWidth": {
    "@value": "0.0",
    "@type": "xsd:decimal"
  },
  "modelRiskLevel": 2,
  "deviceClass": "Class II",
  "couName": "CPB use",
  "decision": "Accepted",
  "hasUncertaintyQuantification": false
}