An advanced expiratory circuit for the recovery of perfluorocarbon liquid from non-saturated perfluorocarbon vapour during partial liquid ventilation: an experimental model.
BACKGROUND
The loss of perfluorocarbon (PFC) vapour in the expired gases during partial liquid ventilation should be minimized both to prevent perfluorocarbon vapour entering the atmosphere and to re-use the recovered PFC liquid. Using a substantially modified design of our previously described condenser, we aimed to determine how much perfluorocarbon liquid could be recovered from gases containing PFC and water vapour, at concentrations found during partial liquid ventilation, and to determine if the amount recovered differed with background flow rate (at flow rates suitable for use in neonates).


METHODS
The expiratory line of a standard ventilator circuit set-up was mimicked, with the addition of two condensers. Perfluorocarbon (30 mL of FC-77) and water vapour, at concentrations found during partial liquid ventilation, were passed through the circuit at a number of flow rates and the percentage recovery of the liquids measured.


RESULTS
From 14.2 mL (47%) to 27.3 mL (91%) of the infused 30 mL of FC-77 was recovered at the flow rates studied. Significantly higher FC-77 recovery was obtained at lower flow rates (ANOVA with Bonferroni's multiple comparison test, p < 0.0001). As a percentage of the theoretical maximum recovery, 64 to 95% of the FC-77 was recovered. Statistically significantly less FC-77 was recovered at 5 Lmin(-1) (ANOVA with Bonferroni's multiple comparison test, p < 0.0001). Amounts of perfluorocarbon vapour recovered were 47%, 50%, 81% and 91% at flow rates of 10, 5, 2 and 1 Lmin(-1), respectively.


CONCLUSIONS
Using two condensers in series 47% to 91% of perfluorocarbon liquid can be recovered, from gases containing perfluorocarbon and water vapour, at concentrations found during partial liquid ventilation.
Dunster
Kimble R
KR
Grantley Stable Neonatal Unit, Royal Women's Hospital, Brisbane, Queensland, Australia. k.dunster@qut.edu.au
Davies
Mark W
MW
Fraser
John F
JF
D005591:Chemical Fractionation / Q000379:methods*; D003198:Computer Simulation; D004867:Equipment Design; D019544:Equipment Failure Analysis; D045853:Exhalation / Q000502:physiology*; D005466:Fluorocarbons / Q000737:chemistry* / Q000302:isolation & purification* / Q000627:therapeutic use; D006801:Humans; D007231:Infant, Newborn; D021061:Liquid Ventilation / Q000295:instrumentation* / Q000379:methods*; D008168:Lung / Q000502:physiology; D008954:Models, Biological; D012123:Pulmonary Ventilation / Q000502:physiology
D005466:Fluorocarbons