bluuebunny/crossref_metadata_2025 huggingface dataset:
Alveolar gas exchange during submarine escape
Authors: DuBois Arthur B. , Bond George F. , Schaefer Karl E.
Published: December 2017

Solution of an equation for alveolar gas exchange during underwater ascent indicates that alveolar carbon dioxide tension should remain constant and normal during ascent owing to the expansion of gases in the lungs. Alveolar gas samples were obtained before and at the end of buoyant ascent from a depth of 90 ft of water. The partial pressure of alveolar carbon dioxide at the end was approximately equal to that at the beginning, as predicted, and the partial pressure of oxygen indicated that the arterial saturation would be almost normal. These findings indicate that buoyant ascents can be made from a depth of at least 90 ft without breathing and without urgency to breathe. Extrapolation of these findings indicates that during ascents from much greater depths there should be little or no urgency to breathe.

Submitted on August 8, 1962
Pulmonary circulation and oxygen transport in lambs at high altitude
Authors: Reeves John T. , Grover Estelle B. , Grover Robert F.
Published: December 2017

The oxygen transport and pulmonary hemodynamics of lambs native to low altitude were evaluated in Denver and on Mount Evans (12,700 ft.). Because the Hb-O2 dissociation curve is placed well to the right of most other mammals, markedly depressed arterial O2 saturations (59%) occurred at high altitude. However, the lambs adapted remarkably well and showed normally rapid growth. The mixed venous Po2 was relatively well maintained, primarily by a narrowing of the A-V Po2 gradient to 11 mm Hg. Despite the marked hypoxemia, elevation of the pulmonary artery pressure was not a consistent finding, and when it occurred it was neither marked nor sustained.

Submitted on June 6, 1962
Compliance of the chest wall in chronic bronchitis and emphysema
Authors: Cherniack R. M. , Hodson A.
Published: December 2017

The respiratory rate was found to be faster and the tidal volume lower than normal in patients with chronic bronchitis and emphysema. The compliance of the total respiratory system, the lungs, and the chest wall was measured in 11 normal subjects and 13 patients with chronic bronchitis, 11 of whom had also developed emphysema. The compliance of the total respiratory system was lower than in the normals in the patients with chronic bronchitis. This was entirely attributable to a reduction in the compliance of the chest wall, that of the lungs being similar to that of the normals. The vital capacity appeared to be related to the compliance of the total respiratory system and was reduced in the patients with chronic bronchitis and emphysema largely because of a diminished distensibility of the chest wall. It is suggested that the low chest wall compliance may explain the paradoxical finding of rapid shallow respirations in these patients with airway obstruction who theoretically would have been expected to breathe slowly and deeply. It is further suggested that the diminished distensibility of the chest wall in patients with chronic bronchitis and emphysema would necessitate an increase in the amount of work done in order to breathe and, therefore, likely contributes to the disability in this disease.

Submitted on April 18, 1962
Influence of temperature on olfactory sensitivity
Authors: Stone Herbert
Published: December 2017

The olfactory response to acetic acid was studied at six experimental temperatures (12.5, 15, 20, 25, 30, and 35 C) for a trained panel of ten subjects. Determination of the 50% thresholds indicated no significant differences in olfactory sensitivity at the various environmental temperatures. Further analysis of the data indicated two significantly different groups of differing absolute sensitivity; however, no influence of temperature on olfactory sensitivity was noted. The 50% threshold for acetic acid was found to be 39.0 x 10-4 mg/liter air (0.65 x 10-7 moles/liter air) for the pooled data. Temperature recordings of inhaled and exhaled air in the nasal cavity suggested inspired air was rapidly equilibrated with body temperature by heat provided by the conchae. These data corroborate the conclusions of the sensory tests and explain the lack of change in odor threshold at different environmental temperatures. The inspired air stream is rapidly warmed to body temperature and any apparent changes in olfactory sensitivity would appear to be physical phenomena and not response to a true olfactory stimulus.

Submitted on January 10, 1963
Aerobic working capacity of Eskimos
Authors: Andersen K. Lange , Hart J. S.
Published: December 2017

The aerobic working capacity was measured in eight young Eskimos. Their maximal oxygen uptake averaged 2.6 liter/min. This is considerably lower than that found in young Caucasian men. The heart rate-oxygen uptake relationship also indicates a lower physiological capacity of the Eskimos. Expressing maximal oxygen uptake on a body weight basis brings about substantial agreement with results of experiments on sedentary-living Scandinavian students. The heart rate taken at the end of the maximal work averaged 173 min for the Eskimos which is about 10% lower than found in Caucasian men, indicating that the work test (bicycling) did not activate the circulatory system of the Eskimos maximally. By assuming a linear correlation between heart rate and O2 consumption up to its maximal value, the maximal O2 uptake would have to be 20% greater to give a maximal heart rate similar to that observed in Caucasian men. The pulmonary ventilation efficiency during exercise was found to be lower in Eskimos than in Caucasian men.

Submitted on February 7, 1963
Effect of exercise on Na and K concentrations in human saliva and serum
Authors: Salminen Simo , Konttinen Aarne
Published: December 2017

The effect of exercise on the salivary Na, K, and protein concentrations and on the serum Na and K concentrations has been studied in young men. The exercise consisted of a march of 2-hr duration. The exercise had no marked effect on the serum Na and K. The salivary Na concentration increased nearly twofold during exercise, and had decreased to its initial value within 2-hr recovery. No noteworthy changes in the salivary K concentration occurred during the experiment. The salivary protein concentration increased during exercise, and this increase was positively correlated with the increase in the salivary Na/K ratio in the same man. These results are ascribed to the increased permeability of the plasma-saliva barrier during the exercise.

Submitted on September 4, 1962
Validation of insorption by blood analysis with comparisons of systemic and portal venous disappearances of D2O, Na24, and K42
Authors: Code Charles F. , Moll Johann C. , Orvis Alan L.
Published: December 2017

The rates of disappearance D2O, Na22/24 and K42 from the arterial blood were determined in 17 dogs following rapid injection of the isotopes into the femoral and portal veins. Differences between systemic and portal venous injections were significant during the early phases of the disappearance of the isotopes (P < 0.05). Systemic insorption was simulated by continuous intravenous injection of D2O, Na22, and K42 at known rates into the femoral vein. The appearance of the isotopes in the arterial blood was determined repeatedly during and after their injection. The rate of injection (simulated insorption) was calculated using the mean systemic arterial disappearance rate. The differences between the calculated and actual rates of injection were insignificant. When portal insorption was simulated by constant injection of the isotope into the portal vein, the calculated rate of injection was not significantly different from the actual rate if the mean portal arterial disappearance curve was used in the calculation. When the systemic arterial disappearance curve was utilized, the calculated rate of injection was slightly faster than the actual rate.

Submitted on July 11, 1962
Cardiopulmonary manifestations with high O2 tensions at atmospheric pressure
Authors: Smith Charles W. , Lehan Patrick H. , Monks James J.
Published: December 2017

Dogs inhaled 95–98% oxygen at atmospheric pressures until they succumbed of respiratory failure after an average of 54.6 hr. At autopsy the lungs were dark red, hemorrhagic, edematous, and congested. Blood gas contents and cardiovascular parameters were maintained essentially normal until approximately 2–3 hr before death. Tidal volume increased, respiratory rate slowed, and intrapleural pressures changed markedly. Pulmonary compliance decreased late in exposure, presumably due to increased turgor of the lungs. Maintenance of normal left atrial pressures was judged to show that left ventricular function was not responsible for the pulmonary edema and congestion.

oxygen toxicity

Submitted on January 14, 1963
Body temperature as a determinant in maze acquisition by mice
Authors: Sudak Frederick N. , Essman Walter B.
Published: December 2017

The effect of increasing the number of training trials and spacing training sessions on acquisition of a simple water-escape response was investigated in mice during a moderate reduction in colonic temperature. Hypothermia was produced by treatment of the animals with 50 mg/kg 2,4-dichlorophenoxyacetic acid (2,4-D) (i.p.) and a 30-min exposure to cold air (2.0 ± 0.5 C). Control animals received 2,4-D and were maintained in a thermoneutral environment (32.0 ± 1 C) to preclude loss of body temperature. Following these procedures, all animals were given four training trials spaced at 15-min intervals. Two days later, the procedures were repeated and four more training trials were given. Acquisition of the escape response occurred within five training trials for animals in which colonic temperatures were reduced 2.6–4.8 C during training. Control animals demonstrated acquisition of the maze habit within two training trials. These data suggest that extending the training trials over an expanded period of time was effective in allowing for acquisition in hypothermic mice and that a reduction in body temperature affects acquisition rate.

animal behavior; learning in hypothermic animals; hypothermia and maze acquisition

Submitted on March 6, 1963
Frequency-dependent compliance at different levels of inspiration in normal adults
Authors: Mills R. J. , Cumming G. , Harris P.
Published: December 2017

Measurements of pulmonary compliance have been made at different respiratory frequencies in 11 normal adults. The observations have been carried out at three levels of inspiration, the constancy of the volume of air in the lungs being checked by body plethysmography. Compliance decreased with an increasing respiratory frequency at each level of inspiration. The effect was greatest at the lowest lung volume, and least at the middle lung volume. Variations in respiratory frequency had no significant effect on the pulmonary resistance.

lung plethysmograph

Submitted on January 31, 1963
Respiratory acclimatization to carbon dioxide
Authors: Schaefer K. E. , Hastings B. J. , Carey C. R. , Nichols G.
Published: December 2017

Twenty-one subjects were exposed to 1.5% CO2 in 21% O2 for 42 days with pre- and postexposure periods on air for 9 days. Respiratory minute volume (Ve) and alveolar pCO2 were increased throughout the exposure to CO2. After transition to air Ve decreased, while pCO2 remained elevated for 9 days. CO2 retention with uncompensated respiratory acidosis lasted for 23 days. CO2 excretion was increased during the 9-day recovery period indicating release of CO2 from the CO2 stores. Oxygen consumption did not change significantly during the experiment. Respiratory acclimatization to CO2 involved a continuous increase in tidal volume while the respiratory rate declined slowly after an initial increase. Changes in respiratory pattern were associated with an increase in physiological and anatomical dead space. A significant increase in the arterial-alveolar pCO2 and alveolar-arterial pO2 gradient indicated the development of an alveolar dead space. The ventilatory response to 5% CO2 was markedly reduced at the end of CO2 exposure.

chronic CO2 exposure; chronic hypercapnia; chronic respiratory acidosis

Submitted on August 31, 1961
Effect of partial immersion in water on response of healthy men to headward acceleration
Authors: Wood Earl H. , Lindberg Evan F. , Code Charles F. , Baldes Edward J.
Published: December 2017

Protection against the effects of headward acceleration afforded by immersion in water has been assayed in the human centrifuge on 15 trained subjects. Immersion in water to the xyphoid afforded an average protection of 1.1 ± 0.1 G for vision and ear opacity and of 1.6 ± 0.2 G for ear pulse and heart rate. Deeper immersion, to the level of the third rib at the sternum increased the protection to 1.8 ± 0.1 G for vision and ear opacity and to 2.8 ± 0.2 G for ear pulse and heart rate. The protection afforded the various physiologic variables increased with the magnitude of acceleration tested. Protection against loss of consciousness may be greater than protection against blackout and is probably similar to the protection afforded the ear pulse and heart rate. The cardiovascular reactions produced by headward acceleration are qualitatively similar with and without water immersion. This finding does not support the concept that impediment to venous return is the primary determinant of man's tolerance to headward acceleration. Visual symptoms occurred at greater amplitudes of ear pulse, and presumably also at greater blood pressures at head level, during water immersion than during control runs.

vision; arterial pressure; heart rate; venous return; arterial pulse in ear

Submitted on May 13, 1963
Effect of temperature on sensitivity of the finger
Authors: Irving Laurence
Published: December 2017

Subjects reported the detection of impacts from objects falling upon the ball of the finger. At a given point on the skin a falling weight of 1 mg might be detected after falling 10 mm, and twice the weight would then be detected after falling 5 mm. Droplets of mercury expelled by a Scholander micrometer burette afforded one series of measurements. On 6 days for one subject the threshold of perceptible impact was least at about 35 C. It increased rapidly as the finger was cooled with Q10 = 4.5 from 35 C to 30 C and with Q10 = 2.5 from 30 C to 20 C. In five other subjects falling droplets of mercury and falling steel ball bearings showed the threshold for detection to increase rather regularly for each individual as the skin was cooled, but on various individual rates with Q10 from 2 to 10. The variation in threshold sensation for impact with temperature raises the question of how heterothermous organisms can estimate and react suitably to some peripheral conditions which must be assessed on absolute scales by means of neural processes that are so thermolabile.

impact tests; sensitivity of finger skin; thermolabile sensation and integration; nervous integration

Submitted on May 20, 1963
Dual purpose pressure chamber with automatic safety devices for animal studies
Authors: Brubach Howard F. , Altland Paul D.
Published: December 2017

The construction and operation of a chamber with positive (up to 500 psi) or negative (simulated altitude to 50,000 ft) pressure with small animals is described. Special regulatory and safety features for low-pressure studies include a barometer connected electrically with a ventilation valve which automatically prevents a pressure drop (less than 100 ft simulated altitude) below a predetermined point, and a valve to prevent backflow of water from the vacuum pump in case of power or equipment failure. A means of controlling the temperature within 1 C is described. For low-pressure work, the chamber is also provided with clear Lucite doors, one of which opens automatically when the pressure is equalized.

altitude; anoxia; aviation medicine; decompression; atmospheric pressure

Submitted on March 26, 1963
Alveolar-arterial oxygen gradient in Andean natives at high altitude
Authors: Kreuzer F. , Tenney S. M. , Mithoefer J. C. , Remmers J.
Published: December 2017

The A-a Do2 (alveolar-arterial oxygen tension difference) was determined at three levels of oxygenation in three groups of subjects: 1) normal persons at sea level, 2) normal Andean natives at high altitude, 3) Andean natives with chronic mountain sickness. The values of A-a Do2 in the Andean natives were uniformly higher than in normal sea-level residents at all levels of oxygenation. These findings were accentuated in patients with chronic mountain sickness. It is concluded that there is no decrease in diffusion barrier for oxygen, and there may be increased veno-arterial shunting in the lung and wider distribution of ventilation-perfusion ratios in the high-altitude residents than in normal subjects at sea level; and that part, at least, of the condition of chronic mountain sickness is an accentuation of these changes.

tissue hypoxia; acclimatization; chronic mountain sickness; secondary polycythemia; pulmonary O2 diffusion barrier; pulmonary veno-arterial shunt; pulmonary ventilation perfusion ratio

Submitted on April 3, 1963
An electronic system for cardiac and metabolic evaluation
Authors: Kubicek W. G. , Patterson R. P.
Published: December 2017

An electronic system was developed that: computes the oxygen consumption rate of a human subject while breathing room air; measures the flow rate of the expired air, expired air minute volume, tidal volume, arterial blood pressure, and pulse rate; and records the electrocardiogram. The flow rate of the expired air and the fraction concentrations of the CO2 and O2 in the expired air are measured with electronic gas analyzers and then electronically computed to give a continuous analog record of the oxygen consumption rate. All of the variables are continuously recorded in analog form. The average values of oxygen consumption rate, arterial blood pressure, or expired air minute volume and pulse rate are recorded in digital form with print out every minute.

analog computer analysis of O2 consumption; continuous analog recording of expired airflow rate and minute volume, tidal volume, arterial blood pressure, and pulse rate; analog-to-digital conversion of O2 consumption, arterial blood pressure, pulse rate, and expired air minute volume; continuous recording of O2 consumption for subject breathing air; continuous electronic computation of O2 consumption

Submitted on June 24, 1963
Electromotive force of transfer systems containing membranes
Authors: Nims Leslie F. , Kuo Jean
Published: December 2017

Reversible Ag-AgCl electrodes have been inserted in the phases of a unit transfer system, phase agr, membrane, phase β, and the electromotive force of the chemical source of electromotive force so produced has been determined in the presence of varying material flows through the membrane. The measured electromotive force was found to be a linear function of the ion-pair chemical potential difference between the phases when the concentration of the salt in the more concentrated phase was less than 0.5 M. This relation implies that an electric transport number, a mutual property of the ion and the membrane, is constant over a wide concentration range when a single salt is present in the system. When the system is in a stationary state, the emf is a linear function of the flow rate of water over the concentration range studied. Two membranes whose electric transport numbers are different, a millipore filter and a cellophane membrane, were used to construct a closed circuit containing two aqueous homogeneous phases of different concentrations. Evidence is presented which demonstrates that a spontaneous electric current flows in such a closed circuit.

membrane phenomena; electric transport number; nonequilibrium systems; electrochemical source of emf in closed circuits

Submitted on June 6, 1963
Evaluation by dye dilution of the pressure-slope method for peripheral run-off
Authors: Pieper Heinz P. , Leverett Sidney D.
Published: December 2017

The reliability of the pressure-slope method for the calculation of peripheral run-off rate has been demonstrated using the dye-dilution technique. The pressure-slope method yields a plot of peripheral run-off rate versus arterial pressure, for a given set of cardiovascular conditions. Under steady-state conditions, the peripheral runoff rate (total arterial outflow) must equal the cardiac output. Thus, a dye-dilution value for cardiac output was correlated with the mean arterial pressure at which it was determined, and then compared to the peripheral run-off rate at the same pressure. The results support the application of the pressure-slope method for the calculation of peripheral run-off rate (and also for the determination of cardiac output) in intact anesthetized dogs.

total arterial outflow; cardiac output determination; pressure-flow relationships in the arterial system

Submitted on December 17, 1962
Gas chromatography in determination of pulmonary diffusing capacity
Authors: Sasahara Arthur A. , Burleson Virginia A.
Published: December 2017

Measurements of pulmonary diffusing capacity (Dco) were made using gas chromatography. The standard breath-holding technic was employed with the modification of using neon instead of helium for the dilution-reference gas. The two basic columns, silica gel, and 13 x molecular sieves were arranged in series on a dual-column chromatograph. All analyses were performed isothermally between 75–85 C with a carrier gas flow rate of 50–60 ml/min. Quantitation of the gas components was made simply and accurately by peak height measurements of the deflection curves on the chromatogram. The normal values for Dco by this method fall well within the range of normals determined by standard technics. The eminent suitability of gas chromatography for the determination of diffusing capacity derives from its simplicity, accuracy, and rapidity of gas analysis and its use of very small volumes of alveolar gas.

breath-holding technic; neon; silica gel; 13 x molecular sieves; isothermic analysis; peak height measurements; dual-column chromatography

Submitted on September 6, 1963
Quantitative evaluation of fibrinolytic enzymes in a simulated human system
Authors: Munson Albert E. , Back Nathan , Ambrus Clara M. , Lassman Howard , Lippschutz Eugene , Ambrus Julian L.
Published: December 2017

A simple in vitro system for the assay of fibrinolytic enzymes intended for therapeutic use has been described. The system employs small quantities of human plasma from outdated bank blood as perfusing medium and purified human fibrin clots labeled with radioactive iodine. Thus, it is possible to follow the dissolution of a human clot without the intervention of reactions of the vascular system (e.g., release of activators). It was shown that the simulated system compares favorably with the in vivo assay. In the assay of a urokinase-activated human plasmin preparation, substitution of human plasma with dog plasma as a perfusing medium resulted in a decrease of the fibrinolytic response. In the case of two preparations, data from the simulated human system correlated well with results of preliminary clinical testing. In using this system as an initial screen for fibrinolytic agents, one must be aware of the fact that in vitro systems represent only part of the mechanisms involved in physiologic or pathologic processes.

fibrinolysin system; plasmin; urokinase; thrombolysis; plasma

Submitted on December 6, 1963
Calibrated vessel for one-step transfer decompression of fluids for gas analysis
Authors: Goodman M. W. , Barnwell G.
Published: December 2017

This report describes a volumetrically calibrated (“to deliver”) glass vessel which has been devised to solve the following fluid-sampling and handling problem: an accurately measured aliquot of the liquid phase of a hyperbaric gas-liquid equilibration system was to be removed from a tonometer located inside a pressurized recompression chamber, decompressed to atmospheric pressure, and displaced into a vacuum extraction chamber for subsequent gas chromatographic analysis of inert gases. It was felt that the pressure change and the manipulative techniques occurring between the original equilibration and the final analysis comprised a constant and significant risk to the entire experiment. This anaerobic fluid-sample transfer vessel limits the entire decompression-transfer phase to a single step, and therefore minimizes opportunities for sample contamination or loss of evolved gas due to anaerobic handling accidents.

hyperbaric exposure; liquid samples; blood-inert gas solubility; gas chromatographic sampling; vacuum extraction of dissolved gases

Submitted on September 4, 1963
Cerebrovascular response to PaCOCO2 during halothane anesthesia in man
Authors: Alexander S. C. , Wollman H. , Cohen P. J. , Chase P. E. , Behar M.
Published: December 2017

Twenty-four measurements of cerebral blood flow (CBF) were made with Kr85 in 13 normal unpremedicated male subjects during halothane anesthesia. Mean end-tidal halothane concentration was 0.98%. Ve was maintained constant in each subject at about 12 liters/min and inhaled co2 concentration was varied so that PaCOCO2 ranged between 19–56 mm Hg. Mean cerebral perfusion pressure varied from 41.0 to 76.4 mm Hg and tended to be lower at PaCOCO2 levels >47 mm Hg. CBF varied linearly with PaCOCO2 under the conditions of this study. The response of the cerebral circulation to change in PaCOCO2 during halothane anesthesia is compared with changes observed by others in awake man and in anesthetized animals. The shape of the PaCOCO2 response curve was observed to be altered by the vasodilatation which occurred during halothane anesthesia. The Kr85 method of calculating CBF is superior to the nitrous oxide technique because of krypton's lower blood solubility and more rapid equilibration.

cerebral blood flow; general anesthesia; carbon dioxide

Submitted on December 23, 1963
Heat reactions of Caucasians and Bantu in South Africa
Authors: Wyndham C. H. , Strydom N. B. , Morrison J. F. , Williams C. G. , Bredell G. A. G. , Von Rahden M. J. E. , Holdsworth L. D. , Van Graan C. H. , Van Rensburg A. J. , Munro A.
Published: December 2017

Heat reactions of 20 Caucasian and 22 Bantu males were compared, first in the unacclimatized state and then in the acclimatized state. The study was conducted at temperatures of 90 F wet-bulb and 93 F dry-bulb at a work rate of 1 liter O2/min consumption. The performances of the unacclimatized Bantu were superior to those of the Caucasians. All 22 Bantu completed the 4-hr experiment, while 10 Caucasians failed. The mean rectal temperature of the Bantu was significantly lower than that of the Caucasians, but not the mean heart rate and mean sweat rate. When both groups were highly acclimatized all men from both groups completed the 4-hr experiment, and their reactions to heat were significantly different from their reactions in the unacclimatized state. Sweat rates, particularly, increased very much. The differences between the two highly acclimatized groups in rectal temperatures, heart rates, and sweat rates (except the 4th hr) were not significant. Although superior in the unacclimatized state, the Bantu does not appear to have an inherent advantage in the ability to regulate the body temperature.

Caucasians versus Bantu in reactions to heat; physiological reactions in exposure to heat

Submitted on August 19, 1963
Heat reactions of Caucasians in temperate, in hot, dry, and in hot, humid climates
Authors: Wyndham C. H. , Strydom N. B. , Munro A. , MacPherson R. K. , Metz B. , Schaff G. , Schieber J.
Published: December 2017

Heat reactions of Australian Caucasians living in hot, humid climates and of French Caucasians living in hot, dry climates were compared to unacclimatized and highly acclimatized male Caucasians living in Johannesburg. The experiments were conducted in climatic chambers at temperatures of 90 F wet-bulb and 93 F dry-bulb, and a workload of 1 liter O2/min consumption. The Australians did not differ significantly from the French in the three reactions to heat, except for a slightly significantly higher sweat rate in the 1st hr. The French and Australians had lower mean rectal temperatures and heart rates and higher sweat rates than the unacclimatized South Africans. Although the trend is toward a significant difference for all hours, the differences are not always significant. Living and working in the hot, humid tropics and in the hot, dry desert evidently confers a certain measure of acclimatization to heat. Quantitatively this can be expressed as 50% of the difference between unacclimatized and acclimatized men. This is, however, considerably less than the condition achieved by systematic artificial acclimatization.

Australian versus French Caucasians in heat reactions; effects of various climates on Caucasians; heat reactions in the desert; heat reactions in the tropics; physiological effects of hot, dry and hot, humid climates

Submitted on August 19, 1963
Continuous measurement of ventilatory exchange ratio during exercise
Authors: Naimark Arnold , Wasserman Karlman , McIlroy Malcolm B.
Published: December 2017

The ventilatory gas exchange ratio (R) has been measured continuously during exercise from end-tidal CO2 and N2 concentrations recorded with gas analyzers. Studies in normal subjects and patients with different working capacities indicate that the change in R at different levels of work lasting several minutes on an ergometer gives an excellent measure of the balance between oxygen supply and demand in the working muscles. The level of work at which R increases appreciably above its resting level corresponds to the level at which arterial lactate increases and plasma bicarbonate falls. The continuous measurement of R can be readily incorporated into work tests for the assessment of exercise performance in both normal subjects and patients with cardiovascular diseases.

blood bicarbonate; work test; anaerobic metabolism; physical fitness; blood lactate

Submitted on December 30, 1963
Pulmonary exchange as related to altered pulmonary mechanics in anesthetized dogs
Authors: Collier Clarence R. , Mead Jere
Published: December 2017

Pulmonary mechanics and gas exchange were studied in supine anesthetized dogs, with and without periodic hyperinflations of the lungs, and after a single forced deflation. After a period without hyperinflations the lung compliance decreased to 66% of control values and patchy atelectasis was observed, but no changes were observed in diffusing capacity (Dl) or per cent venous admixture ( Qva/ Qt). Following a single forced deflation the compliance was 40% of control. Dl was 40% and Qva/ Qt 180% of control values, respectively. These data could be accounted for if there was an accompanying shift of blood flow from atelectatic to nonatelectatic areas, the compensation being very nearly complete for moderate, but less than complete for marked reductions in compliance. Alternative explanations of the apparent compensation are: 1) preferential initial atelectasis of regions with high ventilation-perfusion ratios (as proposed by Farhi) and 2) substantial reductions in compliance without closure of air space, as might result from changes in surface forces with time.

aerotonometer; atelectasis; venous admixture; mechanics of breathing; compliance of dog lungs; diffusion capacity of dog lungs; ventilation perfusion; relationships of dog lungs

Submitted on October 28, 1963
Continuous distribution of specific tidal volume throughout the lung
Authors: Gómez Domingo M. , Briscoe William A. , Cumming Gordon
Published: December 2017

An analytical method is presented which, applied to nitrogen washout data from the lung, describes a continuous distribution of specific tidal volume (or ventilation) throughout the air phase of the lung. The technique of computation is described in some detail. Curves of distribution of specific tidal volume are studied for 12 washout data from normal subjects and for 20 washout data from patients with pulmonary emphysema. In normal subjects the pattern of continuous distribution is an asymmetrical one in which the function starts at zero or very nearly so, increases continuously until it reaches a maximum value, then decreases progressively and becomes negligible for comparatively high values of the specific tidal volume. The formulation expressing this law of distribution is neither that of a normal frequency distribution nor that of a log normal one. With increasing over-all tidal volume in normal subjects the curve is progressively displaced toward the right. In contrast, in pulmonary obstructive diseases the maximum amplitude takes place for very low values of the specific tidal volume and tends to vanish slowly toward values that are higher than in the normal subjects.

apparent volume of lung

Submitted on June 20, 1963
Distribution of blood flow in isolated lung; relation to vascular and alveolar pressures
Authors: West J. B. , Dollery C. T. , Naimark A.
Published: December 2017

The left lung from a dog was removed, ventilated with negative pressure, and perfused with venous blood. Pulmonary arterial, venous, and alveolar pressures could be varied over a large range. The distribution of blood flow in the lung was measured with Xe133. Under these conditions, there was no blood flow above the level at which alveolar equaled arterial pressure (measured at the arterial cannula). Below this level there was a linear increase in blood flow down the lung when the venous pressure was kept low. Raising the venous pressure made the distribution of flow more uniform below the level at which venous and alveolar pressures were equal although flow still increased down this zone. The flow distribution could be completely accounted for by the mechanical effects of the pressure inside and outside the blood vessels which each behaved like a Starling resistance. It was possible to simulate the flow distributions found in man in various physiological and diseased states.

pulmonary; hydrostatic effect; Starling resistance

Submitted on November 15, 1963
Alveolar carbon dioxide equilibria in breath-holding experiments
Authors: Barth Delbert S. , Stacy Ralph W.
Published: December 2017

An investigation was made of the equilibria approached by alveolar CO2 tension in normal human subjects during breath holding. A major objective of this work was to test the hypothesis that the approached equilibrium was with deoxygenated venous rather than with oxygenated venous blood. The study included determination of CO2 tension of expired air by continuous recording before and after breath holding for various time periods, with simultaneous airflow recordings. Pulmonary blood flows were calculated from these data, and were compared with those obtained by an independent rebreathing technique. The findings indicate that the equilibrium approached in the alveolar spaces during breath holding is between the alveolar air and the blood as it enters the pulmonary capillary. This would indicate that CO2 dumping by passive transfer must precede the uptake of oxygen. Effective pulmonary flows calculated from these data were reproducible and in agreement with those obtained by the rebreathing technique.

human pulmonary blood flows; alveolar CO2 transport properties; CO2 rebreathing in humans

Submitted on July 22, 1963
Static volume-pressure characteristics of the respiratory system during maximal efforts
Authors: Cook Charles D. , Mead Jere , Orzalesi Marcello M.
Published: December 2017

Maximal expiratory and inspiratory static airway pressures at different lung volumes were measured in 56 normal subjects of both sexes ranging in age from 6 to 64 years. A new method was used requiring a special mouthpiece, a series of containers of different volumes (allowing volume combinations from 1.5 to 200 liters), and a manometer. The subjects breathed into or out of the containers as forcibly as possible; the lung volumes corresponding to the maximal pressures developed were calculated by Boyle's law. The results are compared with those obtained by other authors. The maximal pressures developed by our subjects, particularly on expiration, were considerably higher than most published values. This was probably the result of using a special mouthpiece which provided an adequate seal even at high pressures. One experienced subject obtained pressures as high as 300 cm H2O on expiration and 200 cm H2O on inspiration.

strength; muscles; pressures; chest

Submitted on November 29, 1963
Performance of a new on-line computer for indicator-dilution curves
Authors: Wessel Hans U. , Hepner Charles F. , James Gordon W. , Kezdi Paul
Published: December 2017

An analog computer was designed for on-line computation of the area under indicator-dilution curves. From a model circulation and from two dogs, 165 tricarbocyanine green dilution curves were recorded with a cuvette densitometer, together with the computed area and signals indicating 60% and 30% of the peak deflection on the down slope of the curve. An IBM 709 digital computer was programmed to compare automatically and conventionally computed flow rates, to analyze sources of error in the computer, and to determine the goodness of fit of the extrapolated exponentials. The results indicated stable operation of the computer. The mean difference between the computer and graphic integration was minus 1.0% ± 2.4% for 78 flow estimates in the model, and 1.9% ± 2.5% for 30 cardiac output in the dogs. Data suggest that the computer does not introduce a significant error provided the dilution curves are also suitable for established graphic methods of integration.

special purpose analog computer; instrumentation; cardiac output

Submitted on December 6, 1963
O2 solubility in blood and temperature correction factors for Po2
Authors: Hedley-Whyte J. , Laver M. B.
Published: December 2017

Tonometry of 100 paired samples of blood and measurement of Po2 before and after warming in a sealed syringe showed that the relative solubility of O2 (αB/αHh2O) in fully saturated blood is constant at all temperatures between 24.5 and 38 C, i.e., fully saturated blood appears to behave as a dilute aqueous solution. When Po2 is kept constant during cooling the relative increase in dissolved O2 in blood is the same as with water. Thus, when cooling from 38 to 20 C the increase in dissolved O2, if Po2 is kept constant, is 31%. Correction factors for the effect of temperature on Po2 of blood warmed to 38 C can be based on ratios of αHh2O38/αHh20T. These factors were found to give adequate correction at O2 tensions above 250 mm Hg. Inaccuracies were found when previously proposed factors were applied to blood having a Po2 of 300 mm Hg. These results were interpreted as showing that blood is essentially fully saturated at a Po2 of approximately 250 mm Hg.

Note

(With the Technical Assistance of A. Murphy and A. Seifen)

relative solubility; agr; hypothermia; hemoglobin; dissociation; tonometry; O2 electrode; physiologic shunt

Submitted on December 23, 1963
Pulmonary and systemic hemodynamics of passively hyperventilated dogs
Authors: Linde Leonard M. , Simmons Daniel H. , Shapiro Bertrand J. , Goldberg Stanley
Published: December 2017

The effects of respiratory alkalosis on pulmonary and systemic hemodynamics in the intact anesthetized dog were measured and compared to a control period with normal pH and pCO2. Pulmonary artery, pulmonary vein, and systemic artery pressures were measured through fluoroscopically placed cardiac catheters. Transmural pressures were determined by subtraction of intrapleural from vascular pressures. Cardiac output was determined in duplicate by the indicator-dilution technique using Cardio-green. Respiratory alkalosis in passively hyperventilated intact anesthetized dogs did not significantly alter cardiac output, or systemic or pulmonary vascular resistance in 13 experiments. The possibility that increased intratracheal pressure during hyperventilation may have mechanically masked a decrease in pulmonary vascular resistance was ruled out in a second series of 17 experiments in which intratracheal pressure was maintained constant. An inverse relationship between pulmonary vascular resistance and pH was not found in this study.

Note:

(With the Technical Assistance of Robert Powell)

pulmonary vascular resistance; pulmonary circulation; respiratory alkalosis; acid-base effects; cardiac output

Submitted on December 19, 1963
Relative compliances of well and poorly ventilated spaces in the normal human lung
Authors: Fowler K. T.
Published: December 2017

A series of experiments was performed in each of which the subject inspired a .25-liter bolus of argon in a large breath consisting otherwise of air. The slope of the argon plateau in the subsequent expiration was found to depend upon the lung volume at which the bolus was administered. When inspiring from residual volume to total lung capacity, bolus injection at a low lung volume led to a rising plateau; injection at medium volume led to a flat plateau; and at a high lung volume to a steeply falling plateau. From measurements of the different plateau slopes produced it was possible to deduce the ratio of the effective compliances shown at any lung volume by the “well” and “poorly” ventilated alveolar populations. In four normal subjects this ratio rose from about 0.5 at residual volume to about 4 near total lung capacity. The qualitative behavior of the two populations resembled that of the upper and lower zones of the erect lung, as indicated by the nature of the cardiac oscillations on the expired gas plateaus.

lung compliance, range of variation; lung compliance, variation with lung volume

Submitted on January 20, 1964
Cardiovascular responses to ice-cold showers
Authors: Keatinge William R. , McIlroy Malcolm B. , Goldfien Alan
Published: December 2017

A shower of ice-cold water (0@#X2013;2.5 C) over the chest caused large increases in systolic and diastolic arterial pressures, pulse pressure, and pulse rate in normal subjects. Cardiac output rose by 59 and 100% in the two subjects in whom it was measured. The changes in pressure were considerably larger than those caused by a cold pressor test or by anxiety. The changes appear to be due to sympathetic nervous reflexes to the heart and blood vessels rather than release of adrenal catecholamines, as plasma epinephrine did not increase and plasma norepinephrine rose only by 0.32 @#X00B5;g/liter. Hyperventilation and evidence of peripheral venoconstriction occurred during the showers, but neither voluntary hyperventilation nor increased venous return from a change in posture produced the changes in blood pressure seen during shower

arterial blood pressure; cardiac output; catecholamines; sympathetic nervous reflexes; hyperventilation; peripheral venoconstriction

Submitted on March 10, 1964
Analysis of a micromethod for transmission oximetry of whole blood
Authors: Loewinger Ezra , Gordon Amirav , Weinreb Arye , Gross Jack
Published: December 2017

The relative roles of absorption and scattering in transmission oximetry of whole blood were examined theoretically and by experiment. It was found that OD 8050 of whole blood is a parabolic function of the hematocrit. The optical density is considerably greater than that of a true solution of hemoglobin except when the hematocrit approaches unity. The optical density is not a linear function of cuvette thickness, again except for hematocrits approaching unity. These experimental results fit the theoretical analysis. Consequently it was possible to design a micromethod for transmission oximetry of whole blood using packed cells in microhematocrit tubes. The correspondence of the modified spectrophotometric method and the gasometric method was sufficiently good to warrant its routine use.

oximetry of packed red cells

Submitted on June 25, 1963
Effect of negative work on the amount of positive work performed by an isolated muscle
Authors: Cavagna G. A. , Saibene F. P. , Margaria R.
Published: December 2017

An isolated frog gastrocnemius tetanically stimulated performs a greater amount of positive work, during shortening at a given speed, if it has been stretched immediately before it was allowed to shorten. The increase of work performed is greater, the shorter the interval between stretching and shortening. A substantial amount of the work done on the contracted muscle during the stretching appears to be available during the shortening phase, as in elastic bodies.

Note:

(With the Technical Assistance of G. Orlando)

tension-length diagram of isolated contracted muscle; elasticity of contracted muscle; efficiency of muscular contraction

Submitted on May 4, 1964
Effects of salicylate on acclimatization to work in the heat
Authors: Bass David E. , Jacobson Eugene D.
Published: December 2017

Some effects of daily large doses of sodium salicylate were studied on the pattern of acclimatization to work in the heat. Acclimatization was induced by daily walks of 100 min on a level treadmill at 3.5 mph at 120/80 F (dry bulb/wet bulb). Two matched groups of six men each were acclimatized in this manner and one group received 5.9–7.8 g of sodium salicylate daily over a period of 10 days. Men treated with salicylate exhibited the same qualitative responses as the control group in terms of the acclimatization process, i.e., their rectal temperatures, skin temperatures, and pulse rates during work in the heat were lower on the later days. Quantitatively, the degree of acclimatization (as measured by rectal temperature) was less in the men receiving salicylate than in the control group. This difference was more apparent than real, however, in that when the salicylate group were taken off the drug regimen, they exhibited the same degree of acclimatization in terms of rectal temperature as did the control group. The acclimatization process did not abolish the acute response to salicylate.

body temperature regulation; exercise; simulated desert environment; simulated jungle environment; hyperthermia; rectal temperature, skin temperature, sweat rate, and pulse rate in hot environments; antipyretics

Submitted on June 15, 1964
Lung diffusing capacity: cyclically and continuously ventilated closed systems
Authors: S⊘lvsteen P.
Published: December 2017

In previous communications, distribution of ventilation and lung diffusing capacity (Dl) were calculated from changes occurring in N2 and CO concentrations when a subject, whose lungs contained atmospheric air at the beginning of the experiment, respired in a spirometer containing oxygen and a little CO. In the calculations, the system was assumed to be continuously ventilated and without dead space. The present study examines which errors may arise from these simplifications. Equations for cyclic ventilation are derived. Definite values for dead space and for volumes, alveolar ventilation, and Dl of two nonuniformly ventilated lung regions are assumed. Thereupon it is computed how the concentrations of N2 and CO will change, if a subject with the assumed values respires in a spirometer of a given volume. From these changes in concentration, Dl and the distribution of ventilation are calculated using equations for continuous ventilation. The differences between the assumed and the calculated values of Dl are small.

mathematics for cyclic ventilation; nonuniform ventilation; calculation of dead space; calculation of lung diffusing capacity

Submitted on February 18, 1964