61 Reliability of cardiac output measurements during catheterisation: comparison of various commonly used formulae calculating assumed oxygen consumption
Bibliographic record
Abstract
Background Cardiac output (CO) measurement guides management of various medical conditions, including but not limited to various adult congenital heart diseases (ACHD), and pulmonary hypertension. It is mandatory to calculate patients’ oxygen consumption (VO2), to measure CO. Ideally VO2 consumption can be measured by using a facemask apparatus; however, due to complexity in their routine use, various formulae derives assumed VO2 are incorporated to obtain CO values. The most commonly used formula in catheter laboratories treating adult patients was reported by LaFarge and Miettinen (1970). However, it was based on data from paediatric population, and their use in adult population is not validated. Moreover, these individual formulae were compared with true VO2 consumption; however, limited information exploring agreement between these formulae is available. Such a comparison is very important, as individual catheter laboratories use these formulae at their discretion to derive cardiac output, influencing patients’ management. Materials and methods We sought to compare cardiac output measurement based upon four commonly used formulas, (1) LaFarge and Miettenen, (2) Dehmer, Firth and Hills, (3) Bergstra, Van Dijk, Jillege, and (4) Seckeler, Hirsch, Beekman Methodology, in 112 ACHD patients who underwent diagnostic catheterization at the Manchester Royal Infirmary, UK between 1st January 2015 to 31st March 2017. Their CO derived by using 4 different formulae were compared using a one way repeated measures ANOVA test. Results CO measured by various formulae is reported here with: LaFarge and Miettenen 4.31±1.43 L/min; Dehmer, Firth and Hills – 4.91±1.50 L/min; Bergstra, Van Dijk, Jillege, – 6.1±2.22 L/min; and Seckeler, Hirsch, Beekman Methodology – 2.96±0.88 L/min. LaFarge and Miettenen formula derived CO was lowest in comparison to all other formulae and was significantly lower than Dehmer as well as Bergstra formulae (p<0.0001 for each), whereas non-significantly lower than the Seckeler et al formula. Conclusion There is no agreement between the assumed VO2 derived cardiac output measurements, including the most commonly used LaFarge formula, when compared in a cohort of ACHD patients. Using such assumed formulae derived CO may be misleading and such values should be interpreted carefully. Every cardiologist should be cognizant of these limitations. Facemask apparatus should be routinely used in catheter laboratories to obtain true VO2, especially, when such a value is likely to influence major management decisions.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.016 | 0.067 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".