Effects of Perfluorocarbon Infusion in an Anesthetized Swine Decompression Model

Introduction: Decompression illness (DCI) results from sudden changes in ambient pressure leading to super-saturation and bubble formation in tissues and the blood stream. Perfluorocarbon emulsions (PFC) increase both oxygen and nitrogen solubility when infused into the blood stream. This study hypothesized that PFC would increase N₂ removal as well as O₂ delivery to tissues. Materials and Methods: Juvenile swine (20kg) were anesthetized and highly instrumented with arterial monitoring, pulmonary artery catheterization, EDAC ultrasound bubble detection, and end tidal N₂ by mass spectrometry. Blood gases were monitored in both the mixed venous and arterial circulation. Full hemodynamics were calculated using standard equations. Four groups of animals were randomized to be either sham controls or compressed and to receive either saline or PFC at 4.5 ml/kg. Animals were dry compressed to 6.8 ATA for 30 minutes of time on the bottom and then rapidly decompressed. Animals were monitored for 120 minutes after surfacing, then euthanized. Results: DCI was created by the dive profile but the severity was variable. Sham animals had no significant changes except that those who received PFC developed significant pulmonary hypertension and decreased cardiac output. This held true for those that also underwent DCI. Respiratory N₂ washout was not significantly different with and without PFC. However, O₂ delivery to tissues was improved with PFC and EDAC bubble count was dramatically less with PFC. Conclusions: PFC decreased bubble generation but the data was confounded by a species specific pulmonary hypertensive response. Even with this as a problem O₂ delivery to tissues was enhanced by PFC. Future work with PFC in different species will help to further understand the contribution of these two mechanisms to treatment efficacy by PFC in DCI.