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To the Editor:—
Dr. Barach's question as to the higher inspired CO2 values, with the Barach-Eckman meter mask than with the BLB mask, puzzled us too at the time of the study, since the Barach-Eckman mask is of a nonrebreathing type, whereas the BLB mask allows partial rebreathing. We did not state in the paper, nor do I now believe, that these differences are important considerations. These data were not included in the original manuscript but were included only after being specifically requested by the reviewer. One might speculate that the end of the sampling tube, although positioned similarly in relation to the patient's nose, may have differed in relation to the "oxygen steam" for the 2 masks, thus creating this discrepancy. Furthermore, a 6 liter per minute flow is a rather low flow rate with which to keep the Barach-Eckman breathing bag filled.Dr. Barach's second point is
Ross C. Kory. Oxygen Therapy. JAMA. 1962;182(5):594. doi:10.1001/jama.1962.03050440086028