Effects of cardiac oscillations and lung volume on acinar gas mixing during apnea

Journal Article · Tue May 01 00:00:00 EDT 1990 · Journal of Applied Physiology (1985); (USA)

OSTI ID:6642629

Mackenzie, C F; Skacel, M; Barnas, G M; Brampton, W J; Alana, C A ^[1]

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1. Univ. of Maryland, Baltimore (USA)

We evaluated the importance of cardiogenic gas mixing in the acini of 13 dogs during 2 min of apnea. 133Xe (1-2 mCi in 4 ml of saline) was injected into an alveolar region through an occluded pulmonary artery branch, and washout was measured by gamma scintillation scanning during continued occlusion or with blood flow reinstated. The monoexponential rate constant for Xe washout (XeW) was -0.4 +/- 0.08 (SE) min-1 at functional residual capacity (FRC) with no blood flow in the injected region. It decreased by more than half at lung volumes 500 ml above and 392 ml below FRC. With intact pulmonary blood flow, XeW was -1.0 +/- 0.08 (SE) min-1 at FRC, and it increased with decreasing lung volume. However, if calculated Xe uptake by the blood was subtracted from the XeW measured with blood flow intact, resulting values at FRC and at FRC + 500 ml were not different from XeW with no blood flow. Reasonable calculation of Xe blood uptake at 392 ml below FRC was not possible because airway closure, increased shunt, and other factors affect XeW. After death, no significant XeW could be measured, which suggests that XeW caused by molecular diffusion was small. We conclude that (1) the effect of heart motion on the lung parenchyma increases acinar gas mixing during apnea, (2) this effect diminishes above or below FRC, and (3) there is probably no direct effect of pulmonary vascular pulsatility on acinar gas mixing.

• OSTI ID: 6642629
• Journal Information: Journal of Applied Physiology (1985); (USA), Vol. 68:5; ISSN 8750-7587
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
LUNGS
DYNAMIC FUNCTION STUDIES
BLOOD FLOW
CARBON DIOXIDE
DOGS
HEART
OXYGEN
SCINTISCANNING
XENON 133
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BODY
CARBON COMPOUNDS
CARBON OXIDES
CARDIOVASCULAR SYSTEM
CHALCOGENIDES
COUNTING TECHNIQUES
DAYS LIVING RADIOISOTOPES
DIAGNOSTIC TECHNIQUES
ELEMENTS
EVEN-ODD NUCLEI
INTERMEDIATE MASS NUCLEI
INTERNAL CONVERSION RADIOISOTOPES
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
MAMMALS
NONMETALS
NUCLEI
ORGANS
OXIDES
OXYGEN COMPOUNDS
RADIOISOTOPE SCANNING
RADIOISOTOPES
RESPIRATORY SYSTEM
VERTEBRATES
XENON ISOTOPES
550601* - Medicine- Unsealed Radionuclides in Diagnostics