The intravenous perfluorocarbon emulsion Oxycyte does not increase hyperbaric oxygen-related seizures in a non-sedated swine model.
OBJECTIVE
Standard treatment for decompression sickness (DCS) is recompression therapy with hyperbaric oxygen (HBO). Non-recompressive therapies are needed to address mass casualty scenarios such as a disabled submarine rescue or DCS therapy in remote environments. Intravenously delivered perfluorocarbon (PFC) emulsions improve blood oxygen content and decrease mortality in several animal models of DCS. However, the enhanced oxygen delivery of PFC emulsions may increase CNS oxygen toxicity (seizures) risk when used in conjunction with HBO. We studied seizure latency and duration in swine randomized to receive PFC or normal saline with 6 ATA of oxygen.


METHODS
Yorkshire swine (n = 31) were fitted with EEG electrodes and randomized to receive 5 ml/kg of the PFC Oxycyte (Oxygen Biotherapeutics Inc., Morrisville, NC) or saline intravenously 1 h before HBO. Unsedated animals were fitted with a snout mask for inhaled gas delivery, positioned inside the hyperbaric chamber, and compressed to 165 ft of sea water (6 ATA). After 2.5 min at 6 ATA, breathing gas was switched to 100 % O2 until signs of seizure were observed and EEG activity was evident. At seizure onset gas was switched back to air for 3 min, then the chamber was decompressed. After 24 h, the dive profile/oxygen exposure was repeated to ensure no secondary effects of PFC drug redistribution or emulsion metabolism.


CONCLUSIONS
Intravenous PFC emulsion did not decrease seizure latency or increase duration on initial HBO exposure or after 24 h. This finding demonstrates the safety of PFC use in conjunction with recompression therapy to treat DCS.
Undersea Medicine Department, Naval Medical Research Center, 503 Robert Grant Ave., Silver Spring, MD, 20910-7500, USA, richard.mahon@med.navy.mil.
Richard T
RT
Mahon
Aaron
A
Hall
Michael
M
Bodo
Charles
C
Auker
D000818:Animals; D003665:Decompression Sickness / Q000503:physiopathology / Q000628:therapy*; D005466:Fluorocarbons / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D006931:Hyperbaric Oxygenation / Q000009:adverse effects*; D007275:Injections, Intravenous; D008297:Male; D010100:Oxygen / Q000633:toxicity; D012640:Seizures / Q000188:drug therapy* / Q000209:etiology / Q000503:physiopathology; D013552:Swine; D014851:Wakefulness
D005466:Fluorocarbons; D010100:Oxygen