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

A. Cortney Henderson, David L. Levin, Susan R. Hopkins, I. Mark Olfert, Richard B. Buxton, G. Kim Prisk

Research output: Contribution to journalArticle

23 Scopus citations

Abstract

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.

Original languageEnglish (US)
Pages (from-to)583-589
Number of pages7
JournalJournal of applied physiology
Volume101
Issue number2
DOIs
StatePublished - 2006

Keywords

  • Arterial spin labeling
  • Functional magnetic resonance imaging
  • Heterogeneity
  • Interstitial pulmonary edema
  • Relative dispersion

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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    Henderson, A. C., Levin, D. L., Hopkins, S. R., Olfert, I. M., Buxton, R. B., & Prisk, G. K. (2006). Steep head-down tilt has persisting effects on the distribution of pulmonary blood flow. Journal of applied physiology, 101(2), 583-589. https://doi.org/10.1152/japplphysiol.00087.2006