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. CONCLUSION: 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

The Impact of International Environmental Agreements: The Case of the Montreal Protocol

There has been a recent economic literature arguing that international environmental agreements (IEAs) can have no real effect, on account of their voluntary and self-enforcing nature. This literature concludes that the terms of IEAs are the codification of the noncooperative equilibrium, and recent empirical work has supported this conclusion in the context of the Montreal Protocol. This paper reaches the opposite conclusion, by means of the comparison of the CFC emissions implicit within the cooperative and noncooperative management paths. The cooperative path is implicit within the terms of the Montreal Protocol. The noncooperative path is implicit in countries' behaviour during the period of unilateral management of CFC emissions. This study estimates the relationship between countries' propensities to produce CFCs and income per capita over the period 1976-1988 (prior to the entry into force of the Montreal Protocol). It then extrapolates this path of unilateral management beyond 1988, and compares it to the obligations adopted under the cooperative regime. This comparison of the projected noncooperative path with the obligations adopted under the Montreal Protocol allows a qualitative test of theories on the economic foundations of self-enforcing IEAs. We find that, in the absence of the Protocol, CFC production (and hence emissions) would have increased by a factor of three over the next fifty years. This study also supplements existing environmental Kuznets curve analyses by providing estimates for the unilateral management for a global externality. In this manner we are able to assess the distributive impacts of the Protocol, in addition to its effectiveness. Using dynamic estimation methods on a panel of around 30 countries over 13 years, the turning point in the relationship between CFC production and income is found to lie around (1986) US$16,000. This implies that developing countries bear the greatest costs in the implementation of the Montreal Protocol