Measurement of Functional Residual Capacity and Ventilation Inhomogeneity by Gas Dilution Techniques

2005 ◽  
pp. 54-65 ◽  
Author(s):  
P.M. Gustafsson ◽  
H. Ljungberg
Keyword(s):  
Functional Residual Capacity ◽  
Ventilation Inhomogeneity ◽  
Residual Capacity ◽  
Gas Dilution

Inter- and intraregional ventilation inhomogeneity in hypergravity and after pressurization of an anti-G suit

2003 ◽  
Vol 94 (4) ◽  
pp. 1353-1364 ◽  
Author(s):  
Mikael Grönkvist ◽  
Eddie Bergsten ◽  
Ola Eiken ◽  
Per M. Gustafsson
Keyword(s):  
Functional Residual Capacity ◽  
Inert Gas ◽  
Phase Iii ◽  
Ventilation Distribution ◽  
Ventilation Inhomogeneity ◽  
Gas Trapping ◽  
Residual Capacity ◽  
Trapped Gas ◽  
Phase Iii Slope

This study assessed the effects of increased gravity in the head-to-foot direction (+Gz) and anti-G suit (AGS) pressurization on functional residual capacity (FRC), the volume of trapped gas (VTG), and ventilation distribution by using inert- gas washout. Normalized phase III slope ( SnIII) analysis was used to determine the effects on inter- and intraregional ventilation inhomogeneity. Twelve men performed multiple-breath washouts of SF6 and He in a human centrifuge at +1 to +3 Gzwearing an AGS pressurized to 0, 6, or 12 kPa. Hypergravity produced moderately increased FRC, VTG, and overall and inter- and intraregional inhomogeneities. In normogravity, AGS pressurization resulted in reduced FRC and increased VTG, overall, and inter- and intraregional inhomogeneities. Inflation of the AGS to 12 kPa at +3 Gz reduced FRC markedly and caused marked gas trapping and intraregional inhomogeneity, whereas interregional inhomogeneity decreased. In conclusion, increased +Gzimpairs ventilation distribution not only between widely separated lung regions, but also within small lung units. Pressurizing an AGS in hypergravity causes extensive gas trapping accompanied by reduced interregional inhomogeneity and, apparently, results in greater intraregional inhomogeneity.

scholarly journals Postnatal Dexamethasone (DEX) Increases Functional Residual Capacity (FRC) and Respiratory Compliance (CRS) in Both Preterm Females And Males

1999 ◽  
Vol 45 (4, Part 2 of 2) ◽  
pp. 211A-211A
Author(s):  
Cindy T McEvoy ◽  
Susan C Bowling ◽  
Kathleen M Williamson ◽  
Pam McGaw ◽  
M Durand
Keyword(s):  
Functional Residual Capacity ◽  
Respiratory Compliance ◽  
Residual Capacity

Dynamic mechanisms determine functional residual capacity in mice, Mus musculus

1979 ◽  
Vol 46 (5) ◽  
pp. 867-871 ◽  
Author(s):  
A. Vinegar ◽  
E. E. Sinnett ◽  
D. E. Leith
Keyword(s):  
Tidal Volume ◽  
Functional Residual Capacity ◽  
Flow Volume ◽  
Linear Portion ◽  
Volume Curve ◽  
Flow Volume Curve ◽  
Residual Capacity ◽  
Expiratory Flow ◽  
The Difference ◽  
Pentobarbital Sodium Anesthesia

Awake mice (22.6--32.6 g) were anesthetized intravenously during head-out body plethysmography. One minute after pentobarbital sodium anesthesia, tidal volume had fallen from 0.28 +/- 0.04 to 0.14 +/- 0.02 ml and frequency from 181 +/- 20 to 142 +/- 8. Functional residual capacity (FRC) decreased by 0.10 +/- 0.02 ml. Expiratory flow-volume curves were linear, highly repeatable, and submaximal over substantial portions of expiration in awake and anesthetized mice; and expiration was interrupted at substantial flows that abruptly fell to and crossed zero as inspiration interrupted relaxed expiration. FRC is maintained at a higher level in awake mice due to a higher tidal volume and frequency coupled with expiratory braking (persistent inspiratory muscle activity or increased glottal resistance). In anesthetized mice, the absence of braking, coupled with reductions in tidal volume and frequency and a prolonged expiratory period, leads to FRCs that approach relaxation volume (Vr). An equation in derived to express the difference between FRC and Vr in terms of the portion of tidal volume expired without braking, the slope of the linear portion of the expiratory flow-volume curve expressed as V/V, the time fraction of one respiratory cycle spent in unbraked expiration, and respiratory frequency.

Sign in / Sign up

Export Citation Format

Share Document