53. DIFFUSION CAPACITY OF THE LUNGS: MAN 



Dx is the amount of gas in ml (STPD) per min which diffuses through the whole lung, when a mean partial pressure 



rnl £cLS 

 difference of one ram He exists between alveolar air and capillary blood of the lung (Ap). D = — . — ^ r-^ ; therefore. 



the total oxygen consumption of the lungs (Q) is as follows: Q = D02 x Ap. Calculation of D02 from Dqq. D02 - 

 Deo * 1-23. Calculation of DcOz from DcO' Dco^ " ^co " 24.6. Methods: A = single breath CO method of 

 Krogh [1], or modification [ 2) ; B = oxygen method with graphical integration of mean oxygen pressure gradient [ 3]; 

 C = steady state CO method based on arterial CO2 tension; D = steady state CO method based on end tidal gas 

 sampling or assumed dead space value; E = radioactive C^^" method of Kruhoffer. Values are in most cases 

 corrected for lung volume at mid-capacity (sum of residual reserve and half the resting tidal volume) or for the 

 volume at functional residual capacity (sum of residual and reserve volume). Values in parentheses are ranges, 

 estimate "c" of the 95% range (cf Introduction). 



Part 1: AT REST AND DURING ACTIVITY 



/I/ 15% O2 in inspired air. /2/ 12% O2 in inspired air. HI 10% O2 in inspired air. /4/ 10 males, 1 female. 



Contributors : (a) Bartels, H., and Opitz. E., (b) Bates, D. V. 



References : [ 1] Krogh, M., J. Physiol., Lend. 49:271, 1914-15. [2] Forster, R. E., Cohn. J. E., Briscoe, 



W. A., Blakemore, W. S., and Riley, R. L., J. Clin. Invest. 33:1417, 1955. [3] Bohr, C, Skand. Arch. Physiol., 



Berl. 22:221. 1909. [4] B^je, O., Arbeitsphysiologie 7:1 57, 1934. [5] Kruhoffer, P., Acta physiol. scand. 32: 106, 



1954. Tb] Bartels. H., et al, Pflugers Arch. 26]^: 99, 1955. [7] Lilienthal, J. L.. Jr., Riley, R. L., Proerarael. 



D. D., and Franke, R. E., Am. J. Physiol. 147:199, 1946. [8] Filley, G. F., Macintosh, D. J., and Wright, G. W., 



J. Clin. Invest. 33:530, 1954. [9] Bates, D. V., Boucot, N. G., and Dormer, A. E., J. Physiol., Lond. 129:237, 



1955. 



Part U: EFFECT OF ACCLIMATIZATION TO ALTITUDE 



/I/ Altitude 13,000 feet at Cerro di Pasco, Peru. /2/ At 20,000 feet after 22 days in low-pressure chamber fnllow- 

 ing gradual ascent. /3/ One subject. 



Contributors : Bartels, H., and Opitz, E. 



References: [1) Barcroft, J., "The Respiratory Function of the Blood," vol 1. London: Cambridge University 

 Press, 1925. (2) Houston, C. S., and Riley, R. L., Am. J. Physiol. 149:565, 1947. 



52 



