A Shout Instead of a Whisper: Let's Get the Graphics Right—Reply

In reply:

After politely conceding to his original objections back in 2013, and thanking him for “his compulsion for accuracy and obsession to detail,”^1,2 I am now amused and a bit annoyed by Mr Chatburn's letter, which expresses his incessant intellectual banter and expert opinion on how the axis of the volumetric capnogram should be labeled in a peer-reviewed publication.³

In the pure technical sense, Mr Chatburn is absolutely correct in that fractional CO₂ is essential to the accuracy of the volumetric CO₂ calculation and for the calculation of areas representing the dimension of volumes of CO₂. However, I would like to point out to Mr Chatburn that there are numerous examples of journal articles, presentations at educational meetings, ventilator graphics, and volumetric capnography monitors that depict or display the vertical axis of the volumetric capnogram in the manner that appears throughout my paper³ in Figures 4, 5, 6, 13, 14, 15, 18, and 19.

Certainly, a scientist or engineer studying, designing, or building a volumetric capnography device would understand this and create the appropriate calculations. However, for the rest of us folks, it makes more sense to view the vertical axis labeled P_CO2 because that is how it is normally seen in the real world.

Maybe it would help if Mr Chatburn could imagine that everywhere P_CO2 appears in the vertical axis of the figures in question, inside invisible brackets next to P_CO2 is the equation, [P_CO2 = F_CO2 × (P_B − 47)], where F_CO2 = fractional concentration of CO₂, P_B = barometric pressure, and 47 = water vapor pressure at 37°C. I should hope this might be enough to justify my author's prerogative instead of being seen as an egregious and confusing violation of depicting dimensionless and erroneous graphic illustrations.

To his credit, if not for Mr Chatburn's scrutiny, I would have overlooked the error in the lower right corner of Figure 13 that was missed during the review and editing process. In place of the infinity symbol (∞) should have been the proportional to symbol (∝).³ I am surprised that this missed Mr Chatburn's scope of intense review and his quest for policing perfection and that I wasn't reprimanded again for another error.²

Perhaps instead of shouting about getting the graphics right, Mr Chatburn should put some thought into the maxims of professional etiquette in constructive criticism.

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