Absorption of in vivo inert gas bubbles

Hlastala, Michael P.; Liew, Hugh D. Van

doi:10.1016/0034-5687(75)90109-7

Cited by 43 publications

(34 citation statements)

References 8 publications

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“…The air in the lungs is at the body temperature ͑37°C , 310 K͒, ambient pressure ͑750 mm Hg͒, and is saturated with a water vapor pressure of 47 mm Hg. 34 The air in the spirometer is at the ambient or room temperature ͑22°C, 295 K, measured within 1% variation͒, ambient pressure ͑750 mm Hg͒, and has a relative humidity of about 50%, giving a water vapor pressure of 10.5 mm Hg. 34 Several approximations were used here and were addressed below and in the Discussion section.…”

Section: Accuracy Of 4d Ctmentioning

confidence: 99%

“…34 The air in the spirometer is at the ambient or room temperature ͑22°C, 295 K, measured within 1% variation͒, ambient pressure ͑750 mm Hg͒, and has a relative humidity of about 50%, giving a water vapor pressure of 10.5 mm Hg. 34 Several approximations were used here and were addressed below and in the Discussion section. The sum of dV / d was taken over all N couch positions that contain air ͑lung and trachea͒.…”

Section: Accuracy Of 4d Ctmentioning

confidence: 99%

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Quantitation of the reconstruction quality of a four‐dimensional computed tomography process for lung cancer patients

Parikh

Naqa

et al. 2005

Medical Physics

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We have developed a four-dimensional computed tomography (4D CT) technique for mapping breathing motion in radiotherapy treatment planning. A multislice CT scanner (1.5 mm slices) operated in ciné mode was used to acquire 12 contiguous slices in each couch position for 15 consecutive scans (0.5 s rotation, 0.25 s between scans) while the patient underwent simultaneous quantitative spirometry measurements to provide a sorting metric. The spirometry-sorted scans were used to reconstruct a 4D data set. A critical factor for 4D CT is quantifying the reconstructed data set quality which we measure by correlating the metric used relative to internal-object motion. For this study, the internal air content within the lung was used as a surrogate for internal motion measurements. Thresholding and image morphological operations were applied to delineate the air-containing tissues (lungs, trachea) from each CT slice. The Hounsfield values were converted to the internal air content (V). The relationship between the air content and spirometer-measured tidal volume (v) was found to be quite linear throughout the lungs and was used to estimate the overall accuracy and precision of tidal volume-sorted 4D CT. Inspection of the CT-scan air content as a function of tidal volume showed excellent correlations (typically r>0.99) throughout the lung volume. Because of the discovered linear relationship, the ratio of internal air content to tidal volume was indicative of the fraction of air change in each couch position. Theoretically, due to air density differences within the lung and in room, the sum of these ratios would equal 1.11. For 12 patients, the mean value was 1.08 +/- 0.06, indicating the high quality of spirometry-based image sorting. The residual of a first-order fit between v and V was used to estimate the process precision. For all patients, the precision was better than 8%, with a mean value of 5.1% +/- 1.9%. This quantitative analysis highlights the value of using spirometry as the metric in sorting CT scans. The 4D reconstruction provides the CT data required to measure the three-dimensional trajectory of tumor and lung tissue during free breathing.

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Section: Accuracy Of 4d Ctmentioning

confidence: 99%

Section: Accuracy Of 4d Ctmentioning

confidence: 99%

Quantitation of the reconstruction quality of a four‐dimensional computed tomography process for lung cancer patients

Parikh

Naqa

et al. 2005

Medical Physics

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“…In either case, no left-sided contrast would be detected whether intrapulmonary arteriovenous pathways are opened or closed. 2,17,74,75 …”

Section: Introductionmentioning

confidence: 99%

“…Thus, when breathing 100% O 2 , the nitrogen within intravenously injected bubbles created from room air should very quickly diffuse out of the bubbles and cause them to dissolve down to ~20% of their original size. 16,17,74,89–91 Subsequently, other influences (e.g. surface tension, pressure, and flow), should further promote their rapid dissolution before the bubbles ever reach the left heart, regardless of the patency of intrapulmonary arteriovenous anastomoses.…”

Section: Introductionmentioning

confidence: 99%

Pulmonary pathways and mechanisms regulating transpulmonary shunting into the general circulation: An update

Lovering

Elliott

Beasley

et al. 2010

Injury

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Embolic insults account for a significant number of neurologic sequelae following many routine surgical procedures. Clearly, these post-intervention embolic events are a serious public health issue as they are potentially life altering. However, the pathway these emboli utilize to bypass the pulmonary microcirculatory sieve in patients without an intracardiac shunt such as an atrial septal defect or patent foramen ovale, remains unclear. In the absence of intracardiac routes and large diameter pulmonary arteriovenous malformations, inducible large diameter intrapulmonary arteriovenous anastomoses in otherwise healthy adult humans may prove to be the best explanation. Our group and others have demonstrated that inducible large diameter intrapulmonary arteriovenous anastomoses are closed at rest but can open during hyperdynamic conditions such as exercise in more than 90% of healthy humans. Furthermore, the patency of these intrapulmonary anastomoses can be modulated through the fraction of inspired oxygen and by body positioning. Of particular clinical interest, there appears to be a strong association between arterial hypoxemia and neurologic insults, suggesting a breach in the filtering ability of the pulmonary microvasculature under these conditions. In this review, we present evidence demonstrating the existence of inducible intrapulmonary arteriovenous anastomoses in healthy humans that are modulated by exercise, oxygen tension and body positioning. Additionally, we identify several clinical conditions associated with both arterial hypoxemia and an increased risk for embolic insults. Finally, we suggest some precautionary measures that should be taken during interventions to keep intrapulmonary arteriovenous anastomoses closed in order to prevent or reduce the incidence of paradoxical embolism.

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“…Figure 4-16 is a schematic representation of diffusion from a bubble filled with either oxygen, nitrogen, or helium into an adjacent perfusion-limited tissue. 71 Because oxygen is metabolized in tissue, its tension falls rapidly with increasing distance from the bubble. Helium and nitrogen, on the other hand, are metabolically inert and are removed only by perfusion, so their concentration gradients extend deeper into tissue.…”

Section: Effects Of Bubbles On Inert Gas Exchangementioning

confidence: 99%

Inert Gas Exchange and Bubbles

Vann¹

2004

Bove and Davis' Diving Medicine

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Absorption of in vivo inert gas bubbles

Cited by 43 publications

References 8 publications

Quantitation of the reconstruction quality of a four‐dimensional computed tomography process for lung cancer patients

Quantitation of the reconstruction quality of a four‐dimensional computed tomography process for lung cancer patients

Pulmonary pathways and mechanisms regulating transpulmonary shunting into the general circulation: An update

Inert Gas Exchange and Bubbles

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