Dose monitoring in Partial Liquid Ventilation by infrared measurement of expired perfluorochemicals.
Patients undergoing Partial Liquid Ventilation (PLV) with the perfluorochemical liquid perflubron (PFB) continuously evaporate the drug from the lung during ventilatory expiration. In this study, two infrared (IR) devices, a modified industrial analyzer ("experimental prototype") and a custom-designed device suitable for use in a clinical environment ("clinical prototype"), were calibrated and validated on the bench to measure a range of PFB concentrations (CPFB) in a gas stream. PFB loss from the lung (area under the CPFB-vs-time-curve) could be correlated during PLV simulation with changes in tidal volume, breathing rate, and variable CPFB-vs-time profiles. The two IR devices produced nearly identical measurements for the same CPFB standards (maximum deviation = 1.5%). The experimental IR prototype was tested in 17 anesthetized, paralyzed, and ventilated swine (42-53 kg) to quantify the total amount and rate of evaporate loss of PFB over 12 hours of PLV, both with and without periodic supplemental PFB doses. The residual PFB volumes in the animal lungs at the end of the study, as determined by a gravimetric postmortem lung method, were found to agree on average for all animals to within 10% of the residual PFB volume as predicted by the IR approach. Furthermore, the IR signal of CPFB does not appear to correlate with the absolute amount of PFB in the lungs, but may reflect the relative proportion of PFB-wetted airway and alveolar surface. The authors conclude that IR quantitation of PFB evaporative loss is acceptably accurate for extended periods of PLV and may be a useful tool in the clinic for PFB dose monitoring and maintenance, thereby helping to optimize PLV treatment.
Mazzoni
M
M
Alliance Pharmaceutical Corp., San Diego, California 92121, USA.
Nugent
L
L
Klein
D
D
Hoffman
J
J
Sekins
K M
KM
Flaim
S F
SF
D000465:Algorithms; D000818:Animals; D001944:Breath Tests / Q000295:instrumentation*; D002138:Calibration / Q000592:standards; D004305:Dose-Response Relationship, Drug; D004655:Emulsions / Q000008:administration & dosage*; D004867:Equipment Design; D005466:Fluorocarbons / Q000008:administration & dosage* / Q000032:analysis*; D006801:Humans; D006842:Hydrocarbons, Brominated; D008962:Models, Theoretical; D008991:Monitoring, Physiologic / Q000295:instrumentation; D011312:Pressure; D012121:Respiration, Artificial / Q000295:instrumentation* / Q000379:methods; D013055:Spectrophotometry, Infrared / Q000295:instrumentation; D013552:Swine; D013696:Temperature
D004655:Emulsions; D005466:Fluorocarbons; D006842:Hydrocarbons, Brominated; C003072:perflubron