Normal Values for the Hypercapnic Ventilation Response: Effects of Age and the Ability to Ventilate
Why this work is in the frame
A frame that forgets how it found something cannot be audited. These are the routes that admitted this work.
Bibliographic record
Abstract
Normal values reported for the hypercapnic ventilation response (HCVR) vary considerably, but the reported normal values have come from studies containing small sample sizes and/or the subjects were young or of unidentified age. We speculated that age has a major effect on HCVR due to the generally lower maximal ventilation (V<sub>E</sub>max) of elderly subjects. Therefore, we performed a large study to more accurately define the normal range and to reveal any effects which age and sex might have on HCVR. We studied 181 normal subjects (69 males, 112 females) between the ages of 20 and 93 years. Prior to measuring HCVR we measured forced expired volume in 1 s (FEV<sub>1</sub> and forced vital capacity to establish whether lung function was normal and to obtain an estimate of V<sub>E</sub>max. Results for the entire group revealed a significant correlation between FEV<sub>1</sub> and HCVR [HCVR = 0.51 + (0.33 FEV<sub>1</sub>, r = 0.43, p < 0.001], so it is clear that the ability to ventilate can influence HCVR. We also found a significant correlation between age and HCVR [HCVR = 2.08-(0.01•age), r = 0.34, p < 0.001]. The mean HCVR for our male group (1.86 ± 0.541/min•mm Hg) was significantly higher (p < 0.001) than that for the females (1.37 ± 0.60) even though their mean ages were similar (41.3 vs. 41.7 years, respectively). We expect that this difference in HCVR was due to the higher FΕV<sub>1</sub> in males compared to females (3.82 vs. 2.83 liter, respectively). To adjust HCVR for the reduced ability of smaller and older subjects to ventilate we corrected for HCVR (CHCVR) to the subject’s predicted maximal ventilation (35 × FEV<sub>1</sub>) and expressed CHCVR as %V<sub>E</sub>max/mm Hg. CHCVR for males (1.44 ± 0.45 %V<sub>E</sub>max/mm Hg) was not different from that for females (1.39 ± 0.54). We found that the lower limit of normal for CHCVR is approximately 0.57 %V<sub>E</sub>max/mm Hg, regardless of age or gender. On the other hand the lower limit of normal for the HCVR decreased with age, falling from approximately 0.90 l/min•mm Hg for 20 year olds to 0 1/min mm Hg for 87 years olds. Therefore, CHCVR is an index of CO<sub>2</sub> sensitivity which is not age or gender dependent but it still has a large scatter for the normal population.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
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 it