RESPIRATORY REGULATION OF THE CO, CAPACITY 
OF THE BLOOD. 
Ill. THE EFFECTS OF EXCESSIVE PULMONARY VENTILATION. 
By YANDELL HENDERSON anv H. W. HAGGARD. 
(From the Physiological Laboratory, Yale Medical School, New Haven.) 
(Received for publication, December 31, 1917.) 
Pain causes excessive breathing: abnormally intense pulmonary 
ventilation. What part does this ventilation play as an inter- 
mediary between pain and its end results; e.g., the characteristic 
alterations of the CO, capacity of the blood, of venous and ar- 
terial pressure, of oxygen consumption, etc.? For an answer to 
this question we need experiments which afford excessive pul- 
monary ventilation but none of the other conditions of pain. In 
man this test may be made experimentally (so far as one dares 
and is physically able) by prolonged voluntary forced breathing.! 
In animals the problem may be attacked by means of excessive 
artificial respiration. In this paper we shall report some experi- 
ments on the latter line of attack. 3 
There seems to be a misapprehension as to what we mean by excessive 
breathing. One observer writes us from a casualty clearing station in 
France as follows: 
‘*As to excessive breathing, we have made careful observations on 
freshly wounded men both in the trenches and in the casualty clearing 
station, and have found that 7t does not occur. A man was brought in a 
few minutes after he had been hit by a small splinter of a bomb which had 
penetrated his wrist. He was suffering intense pain and was breathing, 
each expiration a grunt, twelve times a minute.” 
We have tried breathing in this way ourselves and find that after doing 
so for 40 seconds an apnea of 20 seconds followed. Quantitatively this 
indicates that, at least as we did it, such breathing involves a 50 per cent 
overventilation. The same writer says, ‘‘The severely wounded com- 
monly testify to feeling no pain.”’ This, we think, corresponds with the 
1 Henderson, Y., Am. J. Physiol., 1909-10, xxv, 321; Bull. Johns Hop- 
kins Hosp., 1910, xxi, 236; J. Pharm. and Exp, Therap., in press. 
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THE JOURNAL OF BIOLOGICAL CHEMISTRY, VOL. XXXIII, NO. 2 
