Nitrogen Uptake During Air Diving
DUKE UNIV MEDICAL CENTER DURHAM NC
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Henrys Law prescribes that the whole-body equilibrium N2 content will change in proportion to changes in the alveolar N2 pressure delta PAN2. Thus, during air diving, increases in PAN2 cause proportionate increases in the whole-body equilibrium N2 content. The resultant respiratory N2 uptake, VN2t, may be expressed as VN2t alpha delta PAN2 ft, where alpha is the whole-body N2 solubility, delta PAN2 is computed using the alveolar gas equation, and ft is a function of time that defines the whole-body response to a unit step change in alveolar N2 pressure. The objective of present work was to quantitatively estimate the form and parameters of ft based upon experimental measurements of N2 uptake in man during diving. Such measurements have not been previously reported. A computer controlled closed-circuit breathing apparatus was developed based on our earlier work, and used to measure N2 uptake in seated resting subjects during dives from sea level to 40 fsw 2.21 ata for 250 min, 80 fsw 3.42 ata for 85 min, and 120 fsw 4.64 ata for 50 min. Each dive was followed by 60 min Of 02 decompression at 30 fsw 1.91 ata. Air-equivalent inspired 02 pressures were maintained and C02 was scrubbed. Decreases in circuit volume corresponding to N2 uptake ml STPD were measured in real-time on a breath-by-breath basis and normalized to body weight.
- Stress Physiology
- Marine Engineering
- Life Support Systems