Simulation of exchanges of multiple gases in bubbles in the body

Burkard, Mark E.; Liew, Hugh D. Van

doi:10.1016/0034-5687(94)90111-2

Cited by 38 publications

(31 citation statements)

References 15 publications

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“…For normal auditory function, ME gas pressure needs to be maintained at near ambient levels. However, isolated biological gas pockets, such as the ME, are not stable at ambient pressure, but exhibit either a progressive volume collapse or, if rigid, an exponential pressure decrease to approach the tissue gas pressure of about ambient‐600 daPa . The anatomical construction of the ME allows for both of these behaviors, wherein ME pressure first exhibits a progressive decrease to a mucosa‐ME hydrostatic pressure gradient of about −250 daPa, and then the ME gas space shows a volume collapse as vascular fluids accumulate to displace the ME gas‐volume .…”

Section: Discussionmentioning

confidence: 99%

“…However, isolated biological gas pockets, such as the ME, are not stable at ambient pressure, but exhibit either a progressive volume collapse or, if rigid, an exponential pressure decrease to approach the tissue gas pressure of about ambient-600 daPa. 27,28 The anatomical construction of the ME allows for both of these behaviors, wherein ME pressure first exhibits a progressive decrease to a mucosa-ME hydrostatic pressure gradient of about 2250 daPa, and then the ME gas space shows a volume collapse as vascular fluids accumulate to displace the ME gasvolume. 1 In healthy MEs, this fate is avoided by periodic ET openings, which establish short duration, ME-NP gas-phase communications, and permit gradient-driven ME-NP gas flow that resets ME pressure at near ambient levels.…”

Section: Discussionmentioning

confidence: 99%

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Oral pseudoephedrine decreases the rate of transmucosal nitrous oxide exchange for the middle ear

et al. 2015

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Objective Determine if oral pretreatment with a vasoconstrictor decreases the blood to middle-ear exchange-rate of the perfusion-limited gas, Nitrous Oxide (N2O). Study Design Randomized, double-blind, crossover study. Methods Ten adult subjects with and 10 without past middle-ear disease completed paired experimental sessions, identical but for oral pretreatment with either pseudoephedrine HCL or lactose placebo. At each session, subjects were fitted with a non-rebreathing mask and breathed room air for 20 minutes (acclimation period), 50% N2O:50% O2 for 20 minutes (experimental period) and 100% O2 for 10 minutes (recovery period). Throughout, heart-rate, blood-pressure and O2 saturation were monitored and bilateral middle-ear pressures were recorded by tympanometry every minute. The primary outcome was the slope of the middle-ear pressure-time function for the experimental period which estimates the volume N2O exchange-rate. Using repeated measures ANOVA, the effects of Group (disease history), Treatment (active vs. placebo) and Period (1 vs. 2) on the recorded vital signs, and of Group, Treatment and Ear (left/right) on the middle-ear pressure-time slope were evaluated for statistical significance. Results Statistically significant effects of Period on O2 saturation (Period 2>Period 1) and of Treatment on heart-rate (Active>Placebo) were documented. Only Treatment was statistically significant for the middle-ear pressure-time slope with a shallower slope characterizing the active treatment session. Conclusion The volume exchange-rate across the middle-ear mucosa of perfusion-limited gases can be modulated pharmacologically. Theoretically, similar drugs can be used to reduce the requisite Eustachian tube opening efficiency for adequate middle-ear pressure regulation.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Oral pseudoephedrine decreases the rate of transmucosal nitrous oxide exchange for the middle ear

et al. 2015

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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%

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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“…Larger emboli, in the size of millilitres, would require even longer resorption time if left untreated, and air bubbles have been observed to persist within the vasculature for more than 48 h [20]. The molar flux of any permeating ideal gas species present in blood and tissues obeys Fick’s first law of diffusion [21,22] whereby each gas will have a flux through the surface area of the gas emboli, driven by the partial pressure difference between the inside of the emboli and surrounding tissue and blood. It is conceivable that larger gas emboli of CO 2 may persist in blood vessels and tissues long enough for them to equilibrate with other gases present in blood and tissues (i.e.…”

Section: Discussionmentioning

confidence: 99%

Resuscitation by hyperbaric exposure from a venous gas emboli following laparoscopic surgery

Kjeld

Hansen

Holler

et al. 2012

Scand J Trauma Resusc Emerg Med

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Venous gas embolism is common after laparoscopic surgery but is only rarely of clinical relevance. We present a 52 year old woman undergoing laparoscopic treatment for liver cysts, who also underwent cholecystectomy. She was successfully extubated. However, after a few minutes she developed cardiac arrest due to a venous carbon dioxide (CO2) embolism as identified by transthoracic echocardiography and aspiration of approximately 7 ml of gas from a central venous catheter. She was resuscitated and subsequently treated with hyperbaric oxygen to reduce the size of remaining gas bubbles. Subsequently the patient developed one more episode of cardiac arrest but still made a full recovery. The courses of events indicate that bubbles had persisted in the circulation for a prolonged period. We speculate whether insufficient CO2 flushing of the laparoscopic tubing, causing air to enter the peritoneal cavity, could have contributed to the formation of the intravascular gas emboli. We conclude that persistent resuscitation followed by hyperbaric oxygen treatment after venous gas emboli contributed to the elimination of intravascular bubbles and the favourable outcome for the patient.

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Simulation of exchanges of multiple gases in bubbles in the body

Cited by 38 publications

References 15 publications

Oral pseudoephedrine decreases the rate of transmucosal nitrous oxide exchange for the middle ear

Oral pseudoephedrine decreases the rate of transmucosal nitrous oxide exchange for the middle ear

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

Resuscitation by hyperbaric exposure from a venous gas emboli following laparoscopic surgery

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