Ventilation above closing volume reduces pulmonary vascular resistance hysteresis

Kevin M. Creamer, Laryssa L. McCloud, Lyle E Fisher, Ina C. Ehrhart

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

The aim of this study was to determine the relationship of pulmonary vascular resistance (PVR) hysteresis and lung volume, with special attention to the effects of ventilation around closing volume (CV). Isolated, blood- perfused canine left lower lung lobes (LLL) were incrementally inflated and deflated. Airway and pulmonary artery pressures (PAP) were recorded after each stepwise volume change. Constant blood flow was provided (600 ml/min) and the pulmonary vein pressure (PVP) was held constant at S cm H2O. PAP changes, therefore, were a direct index of PVR changes. Group 1 lobes underwent a full inflation from complete collapse to total lobe capacity (TLC) followed by a full deflation. Group 2 lobes underwent two deflation/inflation cycles, after an initial full inflation. These cycles, both beginning at TLC, had deflation end above and below CV, respectively. Significant PVR hysteresis was noted when the first inflation and deflation were compared. The maximum difference in PAP on deflation was 3.3 cm H2O or 11%. The mean decrease was 2.7 cm H2O for 18 lobes (p < 0.0001). The PAPs on all subsequent inflations or deflations that began above CV remained 9% lower than the initial inflation (n = 9, p < 0.0001), but were not different from each other. However, the final inflation which began from below CV resulted in a 30% return of PVR hysteresis (mean increase in PAP of 0.8 cm H2O, n = 7, p < 0.004). We conclude that there is hysteresis in the PVR response during ventilation, with decreased PVR during deflation relative to the initial inflation, that this hysteresis is absent when lung volume is maintained greater than CV, and that hysteresis returns when inflation occurs after deflation below CV.

Original languageEnglish (US)
Pages (from-to)1114-1119
Number of pages6
JournalAmerican Journal of Respiratory and Critical Care Medicine
Volume158
Issue number4
DOIs
StatePublished - Jan 1 1998
Externally publishedYes

Fingerprint

Closing Volume
Economic Inflation
Vascular Resistance
Ventilation
Pulmonary Artery
Pressure
Lung
Pulmonary Veins
Canidae

ASJC Scopus subject areas

  • Pulmonary and Respiratory Medicine
  • Critical Care and Intensive Care Medicine

Cite this

Ventilation above closing volume reduces pulmonary vascular resistance hysteresis. / Creamer, Kevin M.; McCloud, Laryssa L.; Fisher, Lyle E; Ehrhart, Ina C.

In: American Journal of Respiratory and Critical Care Medicine, Vol. 158, No. 4, 01.01.1998, p. 1114-1119.

Research output: Contribution to journalArticle

Creamer, Kevin M. ; McCloud, Laryssa L. ; Fisher, Lyle E ; Ehrhart, Ina C. / Ventilation above closing volume reduces pulmonary vascular resistance hysteresis. In: American Journal of Respiratory and Critical Care Medicine. 1998 ; Vol. 158, No. 4. pp. 1114-1119.
@article{5969f4eff3d6435da4659638e97201d6,
title = "Ventilation above closing volume reduces pulmonary vascular resistance hysteresis",
abstract = "The aim of this study was to determine the relationship of pulmonary vascular resistance (PVR) hysteresis and lung volume, with special attention to the effects of ventilation around closing volume (CV). Isolated, blood- perfused canine left lower lung lobes (LLL) were incrementally inflated and deflated. Airway and pulmonary artery pressures (PAP) were recorded after each stepwise volume change. Constant blood flow was provided (600 ml/min) and the pulmonary vein pressure (PVP) was held constant at S cm H2O. PAP changes, therefore, were a direct index of PVR changes. Group 1 lobes underwent a full inflation from complete collapse to total lobe capacity (TLC) followed by a full deflation. Group 2 lobes underwent two deflation/inflation cycles, after an initial full inflation. These cycles, both beginning at TLC, had deflation end above and below CV, respectively. Significant PVR hysteresis was noted when the first inflation and deflation were compared. The maximum difference in PAP on deflation was 3.3 cm H2O or 11{\%}. The mean decrease was 2.7 cm H2O for 18 lobes (p < 0.0001). The PAPs on all subsequent inflations or deflations that began above CV remained 9{\%} lower than the initial inflation (n = 9, p < 0.0001), but were not different from each other. However, the final inflation which began from below CV resulted in a 30{\%} return of PVR hysteresis (mean increase in PAP of 0.8 cm H2O, n = 7, p < 0.004). We conclude that there is hysteresis in the PVR response during ventilation, with decreased PVR during deflation relative to the initial inflation, that this hysteresis is absent when lung volume is maintained greater than CV, and that hysteresis returns when inflation occurs after deflation below CV.",
author = "Creamer, {Kevin M.} and McCloud, {Laryssa L.} and Fisher, {Lyle E} and Ehrhart, {Ina C.}",
year = "1998",
month = "1",
day = "1",
doi = "10.1164/ajrccm.158.4.9711081",
language = "English (US)",
volume = "158",
pages = "1114--1119",
journal = "American Journal of Respiratory and Critical Care Medicine",
issn = "1073-449X",
publisher = "American Thoracic Society",
number = "4",

}

TY - JOUR

T1 - Ventilation above closing volume reduces pulmonary vascular resistance hysteresis

AU - Creamer, Kevin M.

AU - McCloud, Laryssa L.

AU - Fisher, Lyle E

AU - Ehrhart, Ina C.

PY - 1998/1/1

Y1 - 1998/1/1

N2 - The aim of this study was to determine the relationship of pulmonary vascular resistance (PVR) hysteresis and lung volume, with special attention to the effects of ventilation around closing volume (CV). Isolated, blood- perfused canine left lower lung lobes (LLL) were incrementally inflated and deflated. Airway and pulmonary artery pressures (PAP) were recorded after each stepwise volume change. Constant blood flow was provided (600 ml/min) and the pulmonary vein pressure (PVP) was held constant at S cm H2O. PAP changes, therefore, were a direct index of PVR changes. Group 1 lobes underwent a full inflation from complete collapse to total lobe capacity (TLC) followed by a full deflation. Group 2 lobes underwent two deflation/inflation cycles, after an initial full inflation. These cycles, both beginning at TLC, had deflation end above and below CV, respectively. Significant PVR hysteresis was noted when the first inflation and deflation were compared. The maximum difference in PAP on deflation was 3.3 cm H2O or 11%. The mean decrease was 2.7 cm H2O for 18 lobes (p < 0.0001). The PAPs on all subsequent inflations or deflations that began above CV remained 9% lower than the initial inflation (n = 9, p < 0.0001), but were not different from each other. However, the final inflation which began from below CV resulted in a 30% return of PVR hysteresis (mean increase in PAP of 0.8 cm H2O, n = 7, p < 0.004). We conclude that there is hysteresis in the PVR response during ventilation, with decreased PVR during deflation relative to the initial inflation, that this hysteresis is absent when lung volume is maintained greater than CV, and that hysteresis returns when inflation occurs after deflation below CV.

AB - The aim of this study was to determine the relationship of pulmonary vascular resistance (PVR) hysteresis and lung volume, with special attention to the effects of ventilation around closing volume (CV). Isolated, blood- perfused canine left lower lung lobes (LLL) were incrementally inflated and deflated. Airway and pulmonary artery pressures (PAP) were recorded after each stepwise volume change. Constant blood flow was provided (600 ml/min) and the pulmonary vein pressure (PVP) was held constant at S cm H2O. PAP changes, therefore, were a direct index of PVR changes. Group 1 lobes underwent a full inflation from complete collapse to total lobe capacity (TLC) followed by a full deflation. Group 2 lobes underwent two deflation/inflation cycles, after an initial full inflation. These cycles, both beginning at TLC, had deflation end above and below CV, respectively. Significant PVR hysteresis was noted when the first inflation and deflation were compared. The maximum difference in PAP on deflation was 3.3 cm H2O or 11%. The mean decrease was 2.7 cm H2O for 18 lobes (p < 0.0001). The PAPs on all subsequent inflations or deflations that began above CV remained 9% lower than the initial inflation (n = 9, p < 0.0001), but were not different from each other. However, the final inflation which began from below CV resulted in a 30% return of PVR hysteresis (mean increase in PAP of 0.8 cm H2O, n = 7, p < 0.004). We conclude that there is hysteresis in the PVR response during ventilation, with decreased PVR during deflation relative to the initial inflation, that this hysteresis is absent when lung volume is maintained greater than CV, and that hysteresis returns when inflation occurs after deflation below CV.

UR - http://www.scopus.com/inward/record.url?scp=0031794880&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0031794880&partnerID=8YFLogxK

U2 - 10.1164/ajrccm.158.4.9711081

DO - 10.1164/ajrccm.158.4.9711081

M3 - Article

VL - 158

SP - 1114

EP - 1119

JO - American Journal of Respiratory and Critical Care Medicine

JF - American Journal of Respiratory and Critical Care Medicine

SN - 1073-449X

IS - 4

ER -