Draft

119  Ats Mini RIP

119.1 Summary

  • Common Methods of Identifying Hypercapnic Respiratory Failure Produce Meaningfully Different CohortsBrian Locke, Krishna Sundar, Jeanette Brown, Ramikiran Gouripeddi
  • Preliminary Results
  • ABG
  • For accurate determination of
  • Studies of hypercapnic respiratory failure using various definitions
  • Changes in Bicarbonate in Patients at Risk for Obesity Hypoventilation Undergoing Bariatric SurgeryBrian Locke, Conrad Addison, Somya Mishra, Krishna Sundar
  • [HCO3-] – day of surgery

119.2 Slide outline

119.2.1 Slide 1

  • TODO: No text extracted from this slide. ### Slide 2
  • Common Methods of Identifying Hypercapnic Respiratory Failure Produce Meaningfully Different CohortsBrian Locke, Krishna Sundar, Jeanette Brown, Ramikiran Gouripeddi
  • Changes in Bicarbonate in Patients at Risk for Obesity Hypoventilation Undergoing Bariatric SurgeryBrian Locke, Conrad Addison, Somya Mishra, Krishna Sundar ### Slide 3
  • Common Methods of Identifying Hypercapnic Respiratory Failure Produce Meaningfully Different CohortsBrian Locke, Krishna Sundar, Jeanette Brown, Ramikiran Gouripeddi
  • Admitted (ICU or floor) with one of the following diagnostic codes:
  • J96.02 (acute hypercapnic respiratory failure)
  • J96.22 (acute and chronic respiratory failure with hypercapnia)
  • J96.92 (respiratory failure unspecified with hypercapnia)
  • J96.12 (chronic respiratory failure with hypercapnia)
  • E66.2 (morbid obesity with hypoventilation)
  • 30d Readmission rate: 23% (2/3 recurrence)
  • ~CHF. > than MI, AECOPD, PNa
  • Admitted to hospital (Floor or ICU) with ABG showing PaCO2 over 45 mmHg and pH 7.35-7.45
  • COPD (2/3)
  • No COPD (1/3)
  • AHI Median
  • [IQR]
  • 31.9
  • [14.3, 45.6]
  • 66.0
  • [48.0, 83.8]
  • AHI > 5 present
  • 66%
  • 94%
  • AHI > 15 present
  • 51%
  • 81%
    1. Admitted to the ICU
    1. PaCO2 greater than 47.25 mmHg
    1. Procedure code for non-invasive ventilation or invasive mechanical ventilation initiation
  • 163 hospitalizations with hypercapnia per 100,000 person-years. (Roughly the same as PE)
  • ABG PaCO2 > 45 mmHg w/n 24h of admission; exclude iatrogenic, arrest… ### Slide 4
  • Common Methods of Identifying Hypercapnic Respiratory Failure Produce Meaningfully Different CohortsBrian Locke, Krishna Sundar, Jeanette Brown, Ramikiran Gouripeddi
  • Hypothesis 1: The methods used in prior studies of hypercapnic respiratory failure (billing code-, procedural code-, and blood-gas-based criteria) identify different patients.
  • Outcome: Relative Sensitivity; Positive Predictive Agreement
  • Hypothesis 2: The cohorts created by these differ methods differ in risk for outcomes of interest, which hampers interpretation of these studies.
  • Outcome: distribution of age, ethnicity, BMI, and frequency of coexisting diagnoses (OSA, opiate use disorder, COPD, CHF, and neuromuscular disease)
  • 69 Million MRNs aggregated from 50 academic medical centers
  • Deidentified patient level data, including admissions, diagnoses, medications, procedures, and lab values.
  • Missing data? ### Slide 5
  • Preliminary Results
  • ICD Group:
  • Relative sensitivity (vs ABG): 19.8%
  • Positive Predictive Agreement (vs ABG): 47.0%
  • NIV Group:
  • Relative sensitivity (vs ABG): 15.2%
  • Positive Predictive Agreement (vs ABG): 45.2%
  • Common Methods of Identifying Hypercapnic Respiratory Failure Produce Meaningfully Different CohortsBrian Locke, Krishna Sundar, Jeanette Brown, Ramikiran Gouripeddi ### Slide 6
  • ABG
  • Group
  • ICD
  • NIV
  • Age
  • 62±18
  • 65±16
  • 62±17
  • % Female
  • 46%
  • 51%
  • 42%
  • % white
  • 66%
  • 71%
  • 65%
  • % Black
  • 18%
  • 19%
  • 17%
  • BMI
  • 30.4±8.3
  • 33.1±10.3
  • 29.1±8.2
  • % with CHF
  • 37%
  • 30%
  • % with COPD
  • 31%
  • 14%
  • % Opiate UD
  • 6%
  • 3%
  • % Sleep Apnea
  • 23%
  • 24%
  • 10%
  • Remaining Analyses:
  • Stratification by time of ABG
  • Data integrity checks:
  • Require each type of info from source during admission
  • Sensitivity analysis among patients with all 3 data-types
  • Common Methods of Identifying Hypercapnic Respiratory Failure Produce Meaningfully Different CohortsBrian Locke, Krishna Sundar, Jeanette Brown, Ramikiran Gouripeddi ### Slide 7
  • For accurate determination of
  • Frequency of different comorbidities or component causes
  • Morbidity and mortality associated with hypercapnia
  • Who should be included in future studies to determine frequency benefit from treatment
  • … method of patient identification likely matters
  • Interpretability of current research could be improved using standard case definitions (EHR Phenotype)
  • How should we identify these patients for studies?
  • ATS ASPIRE grant
  • Common Methods of Identifying Hypercapnic Respiratory Failure Produce Meaningfully Different CohortsBrian Locke, Krishna Sundar, Jeanette Brown, Ramikiran Gouripeddi ### Slide 8
  • Studies of hypercapnic respiratory failure using various definitions ### Slide 9
  • Changes in Bicarbonate in Patients at Risk for Obesity Hypoventilation Undergoing Bariatric SurgeryBrian Locke, Conrad Addison, Somya Mishra, Krishna Sundar
  • ERS 2018: Obesity-related hypoventilation paradigm ### Slide 10
  • Changes in Bicarbonate in Patients at Risk for Obesity Hypoventilation Undergoing Bariatric SurgeryBrian Locke, Conrad Addison, Somya Mishra, Krishna Sundar
  • Hypothesis 1: [HCO3-] has low enough biologic variation to functional usable surrogate for nocturnal CO2 retention peri-bariatric surgery
  • Outcome: intra-patient variability in measurement, frequency of metabolic disturbances
  • Hypothesis 2: Δ[HCO3-] has construct validity as an index of response to interventions that decrease nocturnal CO2 loading
  • Δ[HCO3-] will be higher in patients who lose more weight, who start and adhere to CPAP. ### Slide 11
  • [HCO3-] – day of surgery
  • Patients: n359 patients who underwent bariatric surgery (mostly bypass) 2011-2016 at U of U
  • Exposures: time of OSA dx, CPAP use, Maximum weight loss
  • Outcome: Change in 6-mo, 1-yr, 2-yr [HCO3-]
  • Changes in Bicarbonate in Patients at Risk for Obesity Hypoventilation Undergoing Bariatric SurgeryBrian Locke, Conrad Addison, Somya Mishra, Krishna Sundar
  • Other analyses:
  • % of patients meeting ERS II or higher OHS
  • % Excluded due to metabolic process ### Slide 12
  • Changes in Bicarbonate in Patients at Risk for Obesity Hypoventilation Undergoing Bariatric SurgeryBrian Locke, Conrad Addison, Somya Mishra, Krishna Sundar
  • Exclusions:
  • (n32,27 w/o pre-, post- data)
  • n15 on diuretic
  • n20 on topiramate
  • n 24 on chronic opiates
  • n9 on other med
  • n9 sCr over 1.3
  • 26% have reason to expect
  • 59 of 222 (26.6%) patients with ERS 2+ OHS
  • Weight loss Nadir at 12 months then weight regain [median 5kg]
  • No HCO3 ‘regain’
  • Regression to the mean ### Slide 13
  • Changes in Bicarbonate in Patients at Risk for Obesity Hypoventilation Undergoing Bariatric SurgeryBrian Locke, Conrad Addison, Somya Mishra, Krishna Sundar
  • Proposed re-analysis:
  • Missing data: multiple imputation with chained equations
  • What proportion of variability of [HCO3-] is inter-vs-intra person? Intraclass correlation coefficient
  • Multilevel (mixed effect) regression model of [HCO3-] with predictor variables: starting [HCO3-], OSA severity (or diagnosis), CPAP adherence, weight loss
  • Outputs continuous; loses interpretability of dichotomization
  • Parallel Coordinate plot (e.g. at side) ### Slide 14
  • TODO: No text extracted from this slide.

119.3 Learning objectives

  • Common Methods of Identifying Hypercapnic Respiratory Failure Produce Meaningfully Different CohortsBrian Locke, Krishna Sundar, Jeanette Brown, Ramikiran Gouripeddi
  • Preliminary Results
  • ABG
  • For accurate determination of
  • Studies of hypercapnic respiratory failure using various definitions

119.4 Bottom line / summary

  • Common Methods of Identifying Hypercapnic Respiratory Failure Produce Meaningfully Different CohortsBrian Locke, Krishna Sundar, Jeanette Brown, Ramikiran Gouripeddi
  • Preliminary Results
  • ABG
  • For accurate determination of
  • Studies of hypercapnic respiratory failure using various definitions

119.5 Approach

  1. TODO: Outline the initial assessment or decision point.
  2. TODO: Outline the next diagnostic or management step.
  3. TODO: Outline follow-up or escalation criteria.

119.6 Red flags / when to escalate

  • TODO: List red flags that require urgent escalation.

119.7 Common pitfalls

  • TODO: Capture common errors or missed steps.

119.8 References

TODO: Add landmark references or guideline citations.

119.9 Slides and assets

119.10 Source materials