Tourniquet Hyperpnea and Its Modification by Agents Which Alter Cerebral Blood Flow*

Abstract

When CO2 is added to the inspired gas of a normal resting subject, the PCO2 of arterial blood rises quickly, but the ventilation rate increases gradually. The lag of ventilation behind change in arterial Pco2 has been ascribed to the time required for the tissues of the respiratory center to come into balance with the altered Pco2 of the perfusing blood (1-3). The response of ventilation to change in arterial Po2 is more prompt, presumably because the peripheral chemoreceptors are more richly perfused (2, 4-7). These relationships have been well established, but there is little information about factors which can affect the rate at which ventilation responds to a bloodborne stimulus.It is possible to produce an abrupt increase in arterial Pco2, as well as other arterial blood changes, by releasing tourniquets which have occluded blood flow through the legs for several minutes (8)(9)(10)(11). A few seconds after the rise in arterial PCO2 begins, there is an abrupt increase in ventilation rate (Figure 1). It is found that the time of onset and the magnitude of this ventilation increase can be markedly altered by a variety of procedures which also have the common property of changing the rate of cerebral blood flow. It is, however, difficult to explain all of the observations satisfactorily in terms of our present understanding of the control of ventilation. It is the purpose of this report to present data on the production and modification of tourniquet hyperpnea with particular reference to apparent variations in the stimulus-response time of ventilation, and to speculate on the meaning of these data.* This work was supported by Research Grant H-4080 from the National Heart Institute, National Institutes of Health, U. S. Public Health Service. This work was presented in part at the Cardiovascular Section of the Joint Sessions of the American Society for Clinical Investigation and the American Federation for Clinical Research, Atlantic City, N. J., May, 1959. METHODSThe subj ects were untrained normal male medical students with an age range of 21 to 31 years. They were not fasting and came to the experiment directly from their work.In outline, the technique consisted of occluding circulation to the legs for 15 minutes by applying arterial tourniquets to the thighs and then releasing the tourniquets suddenly while the subj ect was breathing into a recording spirometer. Multiple arterial blood samples were withdrawn from an indwelling brachial artery needle before and after tourniquet release for analysis of the pH, CO2, and 02 changes produced by this procedure.In detail, the experimental procedure was as follows. The subj ect was placed in the supine position and a Cournand needle was inserted into a brachial artery. The needle was attached by plastic tubing to a manifold with a series of three-way stopcocks to which syringes were attached for rapid withdrawal of small blood samples. Wrap-around blood pressure cuffs, 8 inches in width, were placed on the upper thighs. The cuffs were inflated rapidly to a pressure ...

Clinical, Bronchographic, Radiological, and Physiological Observations in Ten Cases of Asbestosis

“…The well-marked reduction of diffusing capacity in asbestosis confirms the finding of Marks et al (1957), and of Bader et al (1957) and justifies the deductions of Baldwin et al (1949), Wright (1955) and Sartorelli (1957), especially as it was recorded in the presence of excessive ventilation, which is known to increase the Dco (Ross, Frayser, and Hickam, 1958). It will be noted that although the changes in compliance and in Dco are both presumably due to pulmonary fibrosis there is no demonstrable correlation between the two.…”

Observation and Simulation of the Circulation, Acid-Base Balance, and Response to CO 2 in Cheyne-Stokes Respiration

“…Circulation, Volume XXXVII, March 1968 Determinants of Periodic Respiration When the disorders of the cardiorespiratory system in all patients with congestive heart failure reported here are compared, certain similarities and differences appear significant. Reduction in cardiac output, alteration of the CO2 threshold and response and arterial pH and PaC02 are similar in the two groups.…”

“…Circulation, Volume XXXVII, March 1968 Maximum and minimum values for ventilation were obtained over a 10-sec period. Corrections for CO2 sampling were made.…”

“…Circulation, Volume XXXVII, March 1968 Results of CO2 Breathing: Prototype and Model For many years, the effect of inhalation of low percentage of CO2 on the prevention of apnea has been known and its effect is rather uniform. Investigators have applied this method in their studies of periodic breathing since the early part of this century.'…”

“…Detailed derivations have been published by Horgan and Lange and associates.12' 15 The parameters expressed are based upon reasonable estimates of coefficients and dynamic response characteristics obtained in human and animal investigation. Following the development reported previously,9 the chemoreceptor block relates Pco2, pH, and Po2 to alveolar ven-Circulation, Volume XXXVII, March 1968 Since Paco,0 is desired, the following expression of the CO2 dissociation curve is applied8: Ca0O2 = 48 + 0.45 (Paco2-39). (5) The following mathematical approximation of the oxygen dissociation curve at expected Sao2 allowed Ca02 to be expressed as Pa02.…”