The effect of blood flow and diffusion impairment on pulmonary gas exchange: A computer model

Severe anemia is associated with remarkable stability of pulmonary gas exchange (S. Deem, M. K. Alberts, M. J. Bishop, A. Bidani, and E. R. Swenson. J. Appl. Physiol. 83: 240–246, 1997), although the factors that contribute to this stability have not been studied in detail. In the present study, 10 Flemish Giant rabbits were anesthetized, paralyzed, and mechanically ventilated at a fixed minute ventilation. Serial hemodilution was performed in five rabbits by simultaneous withdrawal of blood and infusion of an equal volume of 6% hetastarch; five rabbits were followed over a comparable time. Ventilation-perfusion (V˙a/Q˙) relationships were studied by using the multiple inert-gas-elimination technique, and pulmonary blood flow distribution was assessed by using fluorescent microspheres. Expired nitric oxide (NO) was measured by chemiluminescence. Hemodilution resulted in a linear fall in hematocrit over time, from 30 ± 1.6 to 11 ± 1%. Anemia was associated with an increase in arterial [Formula: see text] in comparison with controls ( P < 0.01 between groups). The improvement in O2 exchange was associated with reducedV˙a/Q˙heterogeneity, a reduction in the fractal dimension of pulmonary blood flow ( P = 0.04), and a relative increase in the spatial correlation of pulmonary blood flow ( P = 0.04). Expired NO increased with anemia, whereas it remained stable in control animals ( P < 0.0001 between groups). Anemia results in improved gas exchange in the normal lung as a result of an improvement in overallV˙a/Q˙matching. In turn, this may be a result of favorable changes in pulmonary blood flow distribution, as assessed by the fractal dimension and spatial correlation of blood flow and as a result of increased NO availability.

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Unilateral lung edema: effects on pulmonary gas exchange, hemodynamics, and pulmonary perfusion distribution

Journal of Applied Physiology ◽

10.1152/jappl.2000.89.4.1513 ◽

2000 ◽

Vol 89 (4) ◽

pp. 1513-1521 ◽

Cited By ~ 8

Author(s):

Klaus Slama ◽

Mareike Gesch ◽

Johannes C. Böck ◽

Sylvia M. Pietschmann ◽

Walter Schaffartzik ◽

...

Keyword(s):

Blood Flow ◽

Gas Exchange ◽

Pulmonary Artery ◽

Venous Pressure ◽

Pulmonary Gas Exchange ◽

The Other ◽

Lung Edema ◽

Pulmonary Perfusion ◽

Central Venous ◽

Fluorescent Microspheres

Two types of unilateral lung edema in sheep were characterized regarding their effects on pulmonary gas exchange, hemodynamics, and distribution of pulmonary perfusion. One edema type was induced with aerosolized HCl (0.15 M, pH 1.0) and the other with NaCl (0.15 M, pH 7.4). Both aerosols were nebulized continuously for 4 h into left lungs. In HCl-treated animals, pulmonary gas exchange deteriorated [from a partial arterial O2 pressure-to-inspired O2 fraction ratio (PaO2 /Fi O2 ) of 254 at baseline to 187 after 4 h HCl]. In addition, pulmonary artery pressure and total pulmonary vascular resistance increased (from 16 to 19 mmHg and from 133 to 154 dyn · s · cm−5, respectively). In NaCl-treated animals, only the central venous pressure significantly increased (from 7 to 9 mmHg). Distribution of pulmonary perfusion (measured with fluorescent microspheres) changed differently in both groups. After HCl application, 6% more blood flow was directed to the treated lung, whereas, after NaCl, 5% more blood flow was directed to the untreated lung. HCl and NaCl treatment both induce an equivalent lung edema, but only HCl treatment is associated with gas exchange alteration and tissue damage. Redistribution of pulmonary perfusion maintains gas exchange during NaCl treatment and decreases it during HCl inhalation.

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Single breath‐hold measurement of pulmonary gas exchange and diffusion in humans with hyperpolarized 129 Xe MR

NMR in Biomedicine ◽

10.1002/nbm.4068 ◽

2019 ◽

Vol 32 (5) ◽

pp. e4068 ◽

Cited By ~ 4

Author(s):

Junshuai Xie ◽

Haidong Li ◽

Huiting Zhang ◽

Xiuchao Zhao ◽

Lei Shi ◽

...

Keyword(s):

Gas Exchange ◽

Pulmonary Gas Exchange ◽

Breath Hold ◽

Single Breath ◽

Single Breath Hold ◽

And Diffusion

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Pulmonary gas exchange response to exercise- and mannitol-induced bronchoconstriction in mild asthma

Journal of Applied Physiology ◽

10.1152/japplphysiol.00108.2008 ◽

2008 ◽

Vol 105 (5) ◽

pp. 1477-1485 ◽

Cited By ~ 27

Author(s):

Phillip A. Muñoz ◽

Federico P. Gómez ◽

Hernán A. Manrique ◽

Josep Roca ◽

Joan A. Barberà ◽

...

Keyword(s):

Blood Flow ◽

Gas Exchange ◽

Minute Ventilation ◽

Forced Expiratory Volume ◽

Pulmonary Gas Exchange ◽

Slow Recovery ◽

Airway Narrowing ◽

Asthmatic Patients ◽

Response To Exercise ◽

Blood Flow Redistribution

Both exercise (EIB) and mannitol challenges were performed in asthmatic patients to assess and compare their pulmonary gas exchange responses for an equivalent degree of bronchoconstriction. In 11 subjects with EIB [27 ± 4 (SD) yr; forced expiratory volume in 1 s (FEV1), 86 ± 8% predicted], ventilation-perfusion (V̇a/Q̇) distributions (using multiple inert gas elimination technique) were measured 5, 15, and 45 min after cycling exercise (FEV1 fall, 35 ± 12%) and after mannitol (33 ± 10%), 1 wk apart. Five minutes after EIB, minute ventilation (V̇e; by 123 ± 60%), cardiac output (Q̇t, by 48 ± 29%), and oxygen uptake (V̇o2; by 54 ± 25%) increased, whereas arterial Po2 (PaO2; by 14 ± 11 Torr) decreased due to moderate V̇a/Q̇ imbalance, assessed by increases in dispersions of pulmonary blood flow (log SDQ̇; by 0.53 ± 0.16) and alveolar ventilation (log SDV̇; by 0.28 ± 0.15) (dimensionless) ( P < 0.01 each). In contrast, for an equivalent degree of bronchoconstriction and minor increases in V̇e, Q̇t, and V̇o2, mannitol decreased PaO2 more intensely (by 24 ± 9 Torr) despite fewer disturbances in log SDQ̇ (by 0.27 ± 0.12). Notwithstanding, mannitol-induced increase in log SDV̇ at 5 min (by 0.35 ± 0.15) was similar to that observed during EIB, as was the slow recovery in log SDV̇ and high V̇a/Q̇ ratio areas, at variance with the faster recovery of log SDQ̇ and low V̇a/Q̇ ratio areas. In asthmatic individuals, EIB provokes more V̇a/Q̇ imbalance but less hypoxemia than mannitol, primarily due to postexercise increases in V̇e and Q̇t benefiting PaO2. V̇a/Q̇ inequalities during both challenges most likely reflect uneven airway narrowing and blood flow redistribution generating distinctive V̇a/Q̇ patterns, including the development of areas with low and high V̇a/Q̇ ratios.

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Inhibition of thrombocyte aggregation during extracorporeal lung assist: a case report

Perfusion ◽

10.1177/0267659107083244 ◽

2007 ◽

Vol 22 (4) ◽

pp. 293-297 ◽

Cited By ~ 11

Author(s):

Alois Philipp ◽

Thomas Müller ◽

Thomas Bein ◽

Maik Foltan ◽

Franz-Xaver Schmid ◽

...

Keyword(s):

Blood Flow ◽

Case Report ◽

Gas Exchange ◽

Acetylsalicylic Acid ◽

Diffusion Distance ◽

Thrombocyte Aggregation ◽

Extracorporeal Lung Assist ◽

End Products ◽

Membrane Oxygenators ◽

And Diffusion

Disclaimer: All authors declare that there are no beneficial arrangements with NovaLung® GmbH, Hechingen, Germany In extracorporeal lung assist, membrane oxygenators are used to improve gas exchange. Accumulations on the membranes of coagulation end products can increase resistance to blood flow and diffusion distance. Thus, functioning of the system can be impaired and, in extreme cases, lead to malfunction which may necessitate change out of the oxygenator. We describe a method that complements conventional continuous heparinisation with the administration of acetylsalicylic acid to inhibit thrombocyte aggregation. Perfusion (2007) 22, 293—298.

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Ventilation and diffusion lung capacity dynamics in destructive pulmonary tuberculosis patients with endobronchial valve treatment

MedAlliance ◽

10.36422/23076348-2020-8-4-80-87 ◽

2020 ◽

Vol 8 (4) ◽

pp. 80-87

Keyword(s):

Lung Function ◽

Gas Exchange ◽

Pulmonary Tuberculosis ◽

Vital Capacity ◽

Pulmonary Gas Exchange ◽

Normal Lung ◽

Airway Patency ◽

Lung Capacity ◽

Endobronchial Valve ◽

And Diffusion

The endobronchial valve block (EVB) improves the treat-ment results of destructive pulmonary tuberculosis (PT), but is accompanied by exclusion of the correspon ding lung part from the breathing act. Data on the lung func-tion against the EVB background in PT patients are scarce. Objective: to evaluate the ventilation and diffusion lung capacity in patients requiring EVB and the dynamics of functional parameters against the endobronchial occlu-sion background. Materials and methods: 78 patients (from 18 to 81 years of age) with destructive pulmonary tuberculosis were observed (spirometry, diffusion lung capacity DLCO, and body plethysmography) before EVB. 28 patients have undergone lung function tests against the background of endobronchial occlusion. Results: Lung function testing before the endoscopic stage of treatment showed that in patients with destruc-tive pulmonary tuberculosis, the obstructive variant of ventilation disorders prevailed (63%); while restrictive (6%) and mixed (9%) variants were less common. Ventila-tion disorders were not detected in 22% of the examined patients. Decrease in pulmonary gas exchange was seen in the absolute majority of the examined patients (86%), including patients with normal lung ventilation. Against the background of endobronchial occlusion, there was a significant decrease in airway parameters (FEV1 de-creased to 0.3l, Rtot was 25% higher than the predicted value), decrease in vital capacity (to 0.2l), increase in the residual volume of the total lung capacity (+ 5.1% of pre-dicted va lue). Only 28.6% of the examined patients had a decrease of DLCO, 60.7% had no significant changes in the pulmonary gas exchange, and 10.7% had an increase of DLCO. The dynamics of most parameters of ventilation and gas exchange in the early (up to 6 weeks) and late periods of EVB (6–8 months) did not differ significantly.Conclusion: Endobronchial occlusion leads to up to a 10% decrease of airway patency and vital capacity com-pared to baseline. A decrease in the main ventilation characteristics was observed both in the early and later stages of EVB, without significantly affecting the diffu-sion lung capacity

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Isoflurane and Sevoflurane Anesthesia in Pigs with a Preexistent Gas Exchange Defect

Anesthesiology ◽

10.1097/00000542-200112000-00022 ◽

2001 ◽

Vol 95 (6) ◽

pp. 1422-1426 ◽

Cited By ~ 12

Author(s):

Axel Kleinsasser ◽

Karl H. Lindner ◽

Christoph Hoermann ◽

Andreas Schaefer ◽

Christian Keller ◽

...

Keyword(s):

Blood Flow ◽

Gas Exchange ◽

Porcine Model ◽

Minimum Alveolar Concentration ◽

Pulmonary Gas Exchange ◽

Inert Gas ◽

Sevoflurane Anesthesia ◽

Isoflurane Anesthesia ◽

Volatile Anesthesia ◽

Normal Ventilation

Background Decreased arterial partial pressure of oxygen (PaO2) during volatile anesthesia is well-known. Halothane has been examined with the multiple inert gas elimination technique and has been shown to alter the distribution of pulmonary blood flow and thus PaO2. The effects of isoflurane and sevoflurane on pulmonary gas exchange remain unknown. The authors hypothesized that sevoflurane with a relatively high minimum alveolar concentration (MAC) would result in significantly more gas exchange disturbances in comparison with isoflurane or control. Methods This study was performed in a porcine model with an air pneumoperitoneum that generates a reproducible gas exchange defect. After a baseline measurement of pulmonary gas exchange (multiple inert gas elimination technique) during propofol anesthesia, 21 pigs were randomly assigned to three groups of seven animals each. One group received isoflurane anesthesia, one group received sevoflurane anesthesia, and one group was continued on propofol anesthesia (control). After 30 min of volatile anesthesia at 1 MAC or propofol anesthesia, a second measurement (multiple inert gas elimination technique) was performed. Results At the second measurement, inert gas shunt was 15 +/- 3% (mean +/- SD) during sevoflurane anesthesia versus 9 +/- 1% during propofol anesthesia (P = 0.02). Blood flow to normal ventilation/perfusion (V(A)/Q) lung areas was 83 +/- 5% during sevoflurane anesthesia versus 89 +/- 1% during propofol anesthesia (P = 0.04). This resulted in a PaO2 of 88 +/- 11 mmHg during sevoflurane anesthesia versus 102 +/- 15 mmHg during propofol anesthesia (P = 0.04). Inert gas and blood gas variables during isoflurane anesthesia did not differ significantly from those obtained during propofol anesthesia. Conclusions In pigs with an already existent gas exchange defect, sevoflurane anesthesia but not isoflurane anesthesia causes significantly more gas exchange disturbances than propofol anesthesia does.

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Pulmonary effects of intravenous atropine induce ventilation perfusion mismatch

Canadian Journal of Physiology and Pharmacology ◽

10.1139/cjpp-2012-0429 ◽

2014 ◽

Vol 92 (5) ◽

pp. 399-404 ◽

Cited By ~ 2

Author(s):

Romolo J. Gaspari ◽

David Paydarfar

Keyword(s):

Blood Flow ◽

Gas Exchange ◽

Pulmonary Blood Flow ◽

Gas Analysis ◽

Pulmonary Gas Exchange ◽

Blood Gas ◽

Arterial Blood Gas ◽

Anticholinergic Medications ◽

Arterial Blood ◽

Intravenous Atropine

Atropine is used for a number of medical conditions, predominantly for its cardiovascular effects. Cholinergic nerves that innervate pulmonary smooth muscle, glands, and vasculature may be affected by anticholinergic medications. We hypothesized that atropine causes alterations in pulmonary gas exchange. We conducted a prospective interventional study with detailed physiologic recordings in anesthetized, spontaneously breathing rats (n = 8). Animals breathing a normoxic gas mixture titrated to a partial arterial pressure of oxygen of 110–120 were exposed to an escalating dose of intravenous atropine (0.001, 0.01, 0.1, 5.0, and 20.0 mg/kg body mass). Arterial blood gas measurements were recorded every 2 min (×5) at baseline, and following each of the 5 doses of atropine. In addition, the animals regional pulmonary blood flow was measured using neutron-activated microspheres. Oxygenation decreased immediately following intravenous administration of atropine, despite a small increase in the volume of inspired air with no change in respiratory rate. Arterial blood gas analysis showed an increase in pulmonary dysfunction, characterized by a widening of the alveolar–arteriole gradient (p < 0.003 all groups except for the lowest dose of atropine). The microsphere data demonstrates an abrupt and marked heterogeneity of pulmonary blood flow following atropine treatment. In conclusion, atropine was found to decrease pulmonary gas exchange in a dose-dependent fashion in this rat model.

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