Hyperinflation is the consequence of a dysbalance of static forces (determining the relaxation volume) and/or of the dynamic components. The relaxation volume is determined by an equilibrium between the elastic recoil of the lungs and of the chest walls. The dynamic components include the pattern of breathing, upper airway resistance and postinspiratory activity of inspiratory muscles. The resp...

The helium dilution technique for the measurement of functional residual capacity (FRC) is reviewed with special reference to anaesthesia. A modification is described which permits measurements to be made during intermittent positive pressure ventilation. This modification causes minimal interference with the circuit as it is used for spontaneous respiration. The measuring circuit may be altern...

The purpose of this study was to evaluate the feasibility of routine functional residual capacity (FRC) measurements in healthy preschool children aged 2.7-6.4 yrs. Furthermore, accuracy and reproducibility were investigated and normal values were collected. A mass-produced closed-circuit helium dilution device (rolling seal) was used. Selection of the 113 healthy children (from the 571 measure...

Like the windbag of a bagpipe, the functional residual capacity (FRC) is the lung volume that acts as a reservoir of air for physiologic use. This reserve volume is particularly important during the period of apnea that occurs during induction of general anesthesia. The balance of the inward elastic recoil of the lung and the outward chest wall forces determines the FRC. Inward recoil forces ar...

OBJECTIVES To measure the flexural strengths and moduli of endodontic post materials and to assess the effect on the calculated flexural properties of varying the diameter/length (D/L) ratio of three-point bend test samples. METHODS Three-point bend testing of samples of 2mm diameter metal and fiber-reinforced composite (FRC) rods was carried out and the mechanical properties calculated at su...

Closing capacity (CC; the lung volume at which dependent lung zones cease to ventilate, presumably as a result of airway closure) and standard lung volumes were measured in twenty-four normal women 21 to 29 years of age in the seated and supine positions. Measurements were made serially during pregnancy and once 6 to 8 weeks post partum (the control period). CC was unchanged during pregnancy, w...

This memo contains a table of commonly occurring headers in headings of e-mail messages. The document compiles information from other RFCs such as RFC 822, RFC 1036, RFC 1123, RFC 1327, RFC 1496, RFC 1521, RFC 1766, RFC 1806 and RFC 1864. A few commonly occurring headers which are not defined in RFCs are also included. For each header, the memo gives a short description and a reference to the R...

Infant multiple breath washout (MBW) testing serves as a primary outcome in clinical studies. However, it is still unknown whether current software algorithms allow between-centre comparisons. In this study of healthy infants, we quantified MBW measurement errors and tried to improve data quality by simply changing software settings. We analyzed best quality MBW measurements performed with an u...

Experimental pneumonia induced by intratracheal application of carrageenan or paraquat increases the functional residual lung capacity (FRC) in rats. The mechanism of this increase is not clear, but a decrease in PO(2) may be involved. To test this possibility, we attempted to eliminate the PO(2) decrease in carrageenan-treated rats by exposing them to hyperoxia. Animals of the first group were...

We compared three methods of reporting maximal expiratory flow (V'maxFRC) measured in partial expiratory flow-volume curves (PEFVCs) at the point of functional residual capacity (FRC). PEFVCs were obtained with the rapid thoracoabdominal compression technique (RTC) on a total of 446 occasions in 281 HIV-negative, asymptomatic infants (4.8-28.1 months old). Three different expressions of V'maxFR...