Cardiac oscillations in expired gas tensions, and regional pulmonary blood flow

1961 ◽  
Vol 16 (5) ◽  
pp. 863-868 ◽  
Author(s):  
K. T. Fowler ◽  
John Read
Keyword(s):  
Blood Flow ◽  
Pulmonary Blood Flow ◽  
Gas Flow ◽  
Normal Subjects ◽  
Gas Mixture ◽  
Gas Flows ◽  
Blood Flows ◽  
Lower Lung ◽  
Expired Gas ◽  
Lying Down

Oscillations in expired gas tensions synchronous with the heartbeat were studied in detail following a tidal inspiration of a gas mixture containing 20.9% oxygen, 20% argon, and the rest nitrogen. A respiratory mass spectrometer continuously analyzed expired gas for argon, oxygen, and carbon dioxide. Simultaneous recordings of expiratory flow rate, expired volume, and electrocardiogram were made where necessary. The gas tension oscillations reflected pulsatile changes in gas flow from regions of different ventilations, blood flows, and Va/Qc ratios. An explanation for the oscillations was developed on the basis of cardiac-induced variations in relative gas flows from upper and lower zones of the lungs. This allowed the identification of these zones with the regions of different Va/Qc ratios, and the calculation of minimum differences in ventilation and blood flow between upper and lower lung zones. Blood flow in the upper lung zones of erect normal subjects was found to be very low, rising considerably on lying down. Three patients with raised left auricular pressures showed high upper zone blood flow in the erect position. Submitted on February 27, 1961

Effect of alveolar hypoxia on zonal distribution of pulmonary blood flow

1963 ◽  
Vol 18 (2) ◽  
pp. 244-250 ◽  
Author(s):  
K. T. Fowler ◽  
John Read
Keyword(s):  
Blood Flow ◽  
Pulmonary Blood Flow ◽  
Normal Subjects ◽  
Vascular Response ◽  
Lower Zone ◽  
Zonal Distribution ◽  
Expired Gas ◽  
Alveolar Hypoxia ◽  
Cardiogenic Oscillations ◽  
To Receive

Redistribution of pulmonary blood flow was studied by means of the cardiogenic oscillations of expired gas tensions in six normal subjects after induction of alveolar hypoxia (13.5% O2 inspired). In three subjects the upper zones of the lungs were found to receive a considerably greater proportion of total pulmonary blood flow during hypoxia in both vertical and horizontal postures. Two subjects showed no redistribution in either position. The response of one subject was intermediate between these two groups. It is concluded that in some subjects there is no pulmonary vascular response to alveolar hypoxia, whereas in others there is a response consisting of preferential lower-zone vasoconstriction of greater or lesser magnitude. Earlier data on the effects of hypoxia on the pulmonary circulation are shown to be consistent with the operation of this mechanism. Submitted on July 16, 1962

Effect of exercise on zonal distribution of pulmonary blood flow

1964 ◽  
Vol 19 (4) ◽  
pp. 672-678 ◽  
Author(s):  
John Read ◽  
K. T. Fowler
Keyword(s):  
Blood Flow ◽  
Pulmonary Blood Flow ◽  
Normal Subjects ◽  
Vertical Posture ◽  
Vasomotor Tone ◽  
Alveolar Volume ◽  
Zonal Distribution ◽  
Expired Gas ◽  
Alveolar Hypoxia ◽  
Cardiogenic Oscillations

Redistribution of pulmonary blood flow was studied by means of the cardiogenic oscillations of expired gas tensions in seven normal subjects during exercise in the vertical posture. The results are expressed in terms of Qr, the ratio of blood flow per unit of alveolar volume between upper and lower zones of the lungs, and are compared with the response of the same subjects to alveolar hypoxia. In six subjects, Qr rose on exercise by an amount which varied from subject to subject and from day to day, depending on the resting level of Qr. A further subject usually failed to increase Qr on exercise. Aminophylline reduced resting Qr in some subjects. It is concluded that the response of Qr to exercise depends on the extent to which active pulmonary vasodilatation occurs. Differences in the response of Qr to exercise, hypoxia, and aminophylline are interpreted in terms of differing initial pulmonary vasomotor tone. gas tension; argon; alveolar volume; alveolar hypoxia Submitted on August 5, 1963

Cardiogenic oscillations as an index of pulmonary blood flow distribution

1963 ◽  
Vol 18 (2) ◽  
pp. 233-243 ◽  
Author(s):  
K. T. Fowler ◽  
John Read
Keyword(s):  
Blood Flow ◽  
Pulmonary Blood Flow ◽  
Human Lung ◽  
Flow Distribution ◽  
Blood Flow Distribution ◽  
Lower Zone ◽  
Blood Flows ◽  
Expired Gas ◽  
Cardiogenic Oscillations ◽  
Instrumental Methods

A relationship has been developed between the amplitudes of cardiogenic oscillations of expired gas tensions and the ratio of blood flows through upper and lower zones of the erect human lung. Instrumental methods have been devised for the accurate measurement of the amplitudes of these oscillations. A theoretical and experimental study was made of the sources of error. The ratio of upper- to lower-zone blood flow could be determined with a reproducibility of ±20% so that changes in this ratio of greater than 20%, attendant upon a stimulus, could be identified. Submitted on July 16, 1962

The effects of artificial lung inflation on pulmonary blood flow and heart rate in the turtle Trachemys scripta.

1997 ◽  
Vol 200 (19) ◽  
pp. 2539-2545
Author(s):  
J Herman ◽  
T Wang ◽  
A W Smits ◽  
J W Hicks
Keyword(s):  
Heart Rate ◽  
Blood Flow ◽  
Lung Volume ◽  
Pulmonary Blood Flow ◽  
Trachemys Scripta ◽  
Spontaneous Ventilation ◽  
Lung Inflation ◽  
Cardiovascular Changes ◽  
Blood Flows ◽  
Stimulation Of

As for most ectothermic vertebrates, the breathing pattern of turtles is episodic, and pulmonary blood flow (Qpul) and heart rate (fH) normally increase several-fold during spontaneous ventilation. While some previous studies suggest that these cardiovascular changes are caused by stimulation of pulmonary stretch receptors (PSRs) during ventilation, it has been noted in other studies that blood flows often change prior to the initiation of breathing. Given the uncertainty regarding the role of PSRs in the regulation of central vascular blood flows, we examined the effect of manipulating lung volume (and therefore PSR stimulation) on blood flows and heart rate in the freshwater turtle Trachemys scripta. Turtles were instrumented with blood flow probes on the left aortic arch and the left pulmonary artery for measurements of blood flow, and catheters were inserted into both lungs for manipulation of lung volume. In both anaesthetized and fully recovered animals, reductions or increases in lung volume by withdrawal of lung gas or injection of air, N2, O2 or 10% CO2 (in room air) had no effect on blood flows. Furthermore, simulations of normal breathing bouts by withdrawal and injection of lung gas did not alter Qpul or fH. We conclude that stimulation of PSRs is not sufficient to elicit cardiovascular changes and that the large increase in Qpul and fH normally observed during spontaneous ventilation are probably caused by a simultaneous feedforward control of central origin.

scholarly journals Steep head-down tilt has persisting effects on the distribution of pulmonary blood flow

2006 ◽  
Vol 101 (2) ◽  
pp. 583-589 ◽  
Author(s):  
A. Cortney Henderson ◽  
David L. Levin ◽  
Susan R. Hopkins ◽  
I. Mark Olfert ◽  
Richard B. Buxton ◽  
...  
Keyword(s):  
Blood Flow ◽  
Pulmonary Blood Flow ◽  
Regional Blood Flow ◽  
Flow Distribution ◽  
Normal Subjects ◽  
Relative Dispersion ◽  
Lung Water ◽  
Before And After ◽  
Capillary Pressures ◽  
The Right

Head-down tilt has been shown to increase lung water content in animals and alter the distribution of ventilation in humans; however, its effects on the distribution of pulmonary blood flow in humans are unknown. We hypothesized that head-down tilt would increase the heterogeneity of pulmonary blood flow in humans, an effect analogous to the changes seen in the distribution of ventilation, by increasing capillary hydrostatic pressure and fluid efflux in the lung. To test this, we evaluated changes in the distribution of pulmonary blood flow in seven normal subjects before and after 1 h of 30° head-down tilt using the magnetic resonance imaging technique of arterial spin labeling. Data were acquired in triplicate before tilt and at 10-min intervals for 1 h after tilt. Pulmonary blood flow heterogeneity was quantified by the relative dispersion (standard deviation/mean) of signal intensity for all voxels within the right lung. Relative dispersion was significantly increased by 29% after tilt and remained elevated during the 1 h of measurements after tilt (0.84 ± 0.06 pretilt, 1.09 ± 0.09 calculated for all time points posttilt, P < 0.05). We speculate that the mechanism most likely responsible for our findings is that increased pulmonary capillary pressures and fluid efflux in the lung resulting from head-down tilt alters regional blood flow distribution.

scholarly journals Evaluation of a New Extracorporeal CO2 Removal Device in an Experimental Setting

Membranes ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 8
Author(s):  
Matteo Di Nardo ◽  
Filippo Annoni ◽  
Fuhong Su ◽  
Mirko Belliato ◽  
Roberto Lorusso ◽  
...  
Keyword(s):  
Blood Flow ◽  
Gas Flow ◽  
High Surface ◽  
Surface Membrane ◽  
Respiratory Acidosis ◽  
Chronic Obstructive ◽  
Gas Flows ◽  
Co2 Removal ◽  
Extracorporeal Co2 Removal ◽  
Membrane Lung

Background: Ultra-protective lung ventilation in acute respiratory distress syndrome or early weaning and/or avoidance of mechanical ventilation in decompensated chronic obstructive pulmonary disease may be facilitated by the use of extracorporeal CO2 removal (ECCO2R). We tested the CO2 removal performance of a new ECCO2R (CO2RESET) device in an experimental animal model. Methods: Three healthy pigs were mechanically ventilated and connected to the CO2RESET device (surface area = 1.8 m2, EUROSETS S.r.l., Medolla, Italy). Respiratory settings were adjusted to induce respiratory acidosis with the adjunct of an external source of pure CO2 (target pre membrane lung venous PCO2 (PpreCO2): 80–120 mmHg). The amount of CO2 removed (VCO2, mL/min) by the membrane lung was assessed directly by the ECCO2R device. Results: Before the initiation of ECCO2R, the median PpreCO2 was 102.50 (95.30–118.20) mmHg. Using fixed incremental steps of the sweep gas flow and maintaining a fixed blood flow of 600 mL/min, VCO2 progressively increased from 0 mL/min (gas flow of 0 mL/min) to 170.00 (160.00–200.00) mL/min at a gas flow of 10 L/min. In particular, a high increase of VCO2 was observed increasing the gas flow from 0 to 2 L/min, then, VCO2 tended to progressively achieve a steady-state for higher gas flows. No animal or pump complications were observed. Conclusions: Medium-flow ECCO2R devices with a blood flow of 600 mL/min and a high surface membrane lung (1.8 m2) provided a high VCO2 using moderate sweep gas flows (i.e., >2 L/min) in an experimental swine models with healthy lungs.

Single-breath breath-holding estimate of pulmonary blood flow in man: comparison with direct Fick cardiac output

1989 ◽  
Vol 76 (6) ◽  
pp. 673-676 ◽  
Author(s):  
A. H. Kendrick ◽  
A. Rozkovec ◽  
M. Papouchado ◽  
J. West ◽  
G. Laszlo
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Pulmonary Blood Flow ◽  
Hold Time ◽  
Normal Subjects ◽  
Breath Holding ◽  
Breath Hold ◽  
Single Breath ◽  
Significant Difference ◽  
Cardiac Disorders

1. Resting pulmonary blood flow (Q.), using the uptake of the soluble inert gas Freon-22 and an indirect estimate of lung tissue volume, has been estimated during breath-holding (Q.c) and compared with direct Fick cardiac output (Q.f) in 16 patients with various cardiac disorders. 2. The effect of breath-hold time was investigated by comparing Q.c estimated using 6 and 10 s of breath-holding in 17 patients. Repeatability was assessed by duplicate measurements of Q.c in the patients and in six normal subjects. 3. Q.c tended to overestimate Q.f, the bias and error being 0.09 l/min and 0.59, respectively. The coefficient of repeatability for Q.c in the patients was 0.75 l/min and in the normal subjects was 0.66 1/min. For Q.f it was 0.72 l/min. There was no significant difference in Q.c measured at the two breath-hold times. 4. The technique is simple to perform, and provides a rapid estimate of Q., monitoring acute and chronic changes in cardiac output in normal subjects and patients with cardiac disease.

Pulmonary and bronchial circulatory responses to segmental lung injury

1999 ◽  
Vol 87 (5) ◽  
pp. 1931-1936 ◽  
Author(s):  
S. Lakshminarayan ◽  
S. Bernard ◽  
N. L. Polissar ◽  
R. W. Glenny
Keyword(s):  
Blood Flow ◽  
Lung Injury ◽  
Pulmonary Blood Flow ◽  
Left Lung ◽  
Absolute Increase ◽  
Blood Flows ◽  
Reference Flow ◽  
Injured Area ◽  
Spatial Coordinates ◽  
Blood Flow Increase

In regional lung injury, pulmonary blood flow decreases to the injured regions, and anastomotic bronchial blood flow and total bronchial blood flow increase. However, the pattern of redistribution of the two blood flows to the injured and noninjured areas is not known. In six anesthetized sheep, pulmonary and bronchial blood flows were measured with 15-μm fluorescent microspheres by using the reference flow method. Blood flows were measured in the control state and 1 h after instilling 1 ml/kg of 0.1 N hydrochloric acid into a dependent segment of the left lung. The lungs were then removed, dried, and cubed into ∼2-cm cubes while spatial coordinates were noted. Blood flow to each piece was calculated. Mean pulmonary blood flow to the noninjured pieces went from 730 ± 246 to 574 ± 347 ml/min ( P = 0.22), whereas in the injured pieces the pulmonary blood flow decreased from 246 ± 143 to 56 ± 46 ml/min ( P < 0.01). In contrast, bronchial blood flow to the injured pieces increased from 0.51 ± 0.1 to 1.43 ± 0.85 ml/min ( P = 0.005). We measured the change in flow as it related to the distance from the center of the injured area. Pulmonary blood flow decreased most at the center of the injury, whereas bronchial blood flow doubled at the center of injury and decreased with the distance away from the injury. The absolute increase in bronchial blood flow was substantially less than the decrease in pulmonary blood flow in the injured pieces. We also partitioned the observed variation in pulmonary and bronchial blood flow into that attributable to structure and that due to lung injury and found that 48% of the variation in pulmonary blood flow could be attributed to structure, whereas in the bronchial circulation 70% was attributable to structure. The reasons for these differences are not known and may reflect the intrinsic properties of the systemic and pulmonary circulations.

Effects of pulmonary blood flow on the fractal nature of flow heterogeneity in sheep lungs

1994 ◽  
Vol 77 (3) ◽  
pp. 1474-1479 ◽  
Author(s):  
S. D. Caruthers ◽  
T. R. Harris
Keyword(s):  
Blood Flow ◽  
Pulmonary Blood Flow ◽  
Flow Distribution ◽  
Random Order ◽  
Portion Size ◽  
Relative Dispersion ◽  
Fractal Nature ◽  
Total Flow ◽  
Blood Flows

The spatial heterogeneity of pulmonary blood flow can be described by the relative dispersion (RD) of weight-flow histograms (RD = SD/mean). Glenny and Robertson (J. Appl. Physiol. 69: 532–545, 1990) showed that RD of flow in the lung is fractal in nature, characterized by the fractal dimension (D) and RD for the smallest realizable volume element (RDref). We studied the effects of increasing total pulmonary blood flow on D and RDref. In eight in situ perfused sheep lung preparations, 15-microns radio-labeled microspheres were injected into the pulmonary artery at five different blood flows ranging, in random order, from 1.5 to 5.0 l/m. The lungs were in zone 2 at the lower flows and in zone 3 at the higher flows. The lungs were removed, dried, cut into 2 x 2 x 2-cm3 pieces, weighed, and then counted for microsphere radioactivity. Fractal plots of log(weight) vs. log(RD) were constructed by iteratively combining neighboring pieces and then calculating RD with the increasingly larger portion size. D, which is one minus the slope of the fit through this plot, was 1.14 +/- 0.09 and did not change as blood flow increased. However, RDref decreased significantly (P < 0.01) as total flow increased. We conclude that the fractal nature of pulmonary blood flow distribution is not altered by changes in overall flow.

scholarly journals Introducing 3D-potting: a novel production process for artificial membrane lungs with superior blood flow design

2021 ◽  
Author(s):  
Felix Hesselmann ◽  
Jannis M. Focke ◽  
Peter C. Schlanstein ◽  
Niklas B. Steuer ◽  
Andreas Kaesler ◽  
...  
Keyword(s):  
Blood Flow ◽  
Hollow Fiber ◽  
Gas Flows ◽  
Hollow Fiber Membranes ◽  
Artificial Membrane ◽  
Two Phase ◽  
Blood Flows ◽  
Suitable Parameter ◽  
Fiber Membranes ◽  
Artificial Lungs

AbstractCurrently, artificial-membrane lungs consist of thousands of hollow fiber membranes where blood flows around the fibers and gas flows inside the fibers, achieving diffusive gas exchange. At both ends of the fibers, the interspaces between the hollow fiber membranes and the plastic housing are filled with glue to separate the gas from the blood phase. During a uniaxial centrifugation process, the glue forms the “potting.” The shape of the cured potting is then determined by the centrifugation process, limiting design possibilities and leading to unfavorable stagnation zones associated with blood clotting. In this study, a new multiaxial centrifugation process was developed, expanding the possible shapes of the potting and allowing for completely new module designs with potentially superior blood flow guidance within the potting margins. Two-phase simulations of the process in conceptual artificial lungs were performed to explore the possibilities of a biaxial centrifugation process and determine suitable parameter sets. A corresponding biaxial centrifugation setup was built to prove feasibility and experimentally validate four conceptual designs, resulting in good agreement with the simulations. In summary, this study shows the feasibility of a multiaxial centrifugation process allowing greater variety in potting shapes, eliminating inefficient stagnation zones and more favorable blood flow conditions in artificial lungs. Graphic abstract

Sign in / Sign up

Export Citation Format

Share Document