Pharmacological interventions to decompression sickness in rats: comparison of five agents.
BACKGROUND
This research investigated whether decompression sickness (DCS) risk or severity could be reduced using drug interventions that are easier to implement and equal to or more efficacious than recompression therapy.


METHODS
Using a rat model of DCS, anti-inflammatory or anticoagulant drugs, including lidocaine, aspirin (ASA), methylprednisolone (MP), alpha-phenyl-N-butylnitrone (PBN), and transsodium crocetinate (TSC) were tested to determine their effect on incidence of DCS, death, and time of symptom onset. Each treatment group consisted of approximately 40 animals that received the drug and approximately 40 controls. Animals were exposed to one of five compression and decompression profiles with pressure ranging from 6.3 ATA (175 fsw) to 8.0 ATA (231 fsw); bottom time was either 60 or 90 min; and decompression rate was either 1.8 or 15 ATA x min(-1). Following decompression, the rats were observed for 30 min while walking on a wheel. DCS was defined as an ambulatory deficit or abnormal breathing.


RESULTS
None of the drugs reached statistical significance for all DCS manifestations. Lidocaine post-dive and MP were the only treatments with marginally (P < 0.15) significant differences in DCS outcomes compared to controls. Lidocaine post-dive significantly decreased the incidence of neurological DCS from 73-51%. MP significantly extended the time of onset of death from DCS from 5.4 min to 7.1 min.


CONCLUSIONS
Of the treatments investigated, lidocaine given post-dive has the best chance of success in adjuvant therapy of DCS. Future studies might investigate adjuvant drugs given in combination or during recompression.
Montcalm-Smith
Elizabeth A
EA
Naval Medical Research Center, Silver Spring, MD, USA.
Fahlman
Andreas
A
Kayar
Susan R
SR
D000399:Air Pressure; D000704:Analysis of Variance; D000818:Animals; D000893:Anti-Inflammatory Agents / Q000008:administration & dosage*; D000925:Anticoagulants / Q000008:administration & dosage*; D001241:Aspirin / Q000008:administration & dosage; D002338:Carotenoids; D003497:Cyclic N-Oxides / Q000008:administration & dosage; D003665:Decompression Sickness / Q000188:drug therapy* / Q000401:mortality / Q000517:prevention & control; D053208:Kaplan-Meier Estimate; D008012:Lidocaine / Q000008:administration & dosage; D008775:Methylprednisolone / Q000008:administration & dosage; D051381:Rats; D017207:Rats, Sprague-Dawley; D016896:Treatment Outcome; D014801:Vitamin A / Q000008:administration & dosage / Q000031:analogs & derivatives
D000893:Anti-Inflammatory Agents; D000925:Anticoagulants; D003497:Cyclic N-Oxides; C487773:trans-sodium crocetinate; D014801:Vitamin A; D002338:Carotenoids; C029217:phenyl-N-tert-butylnitrone; D008012:Lidocaine; D001241:Aspirin; D008775:Methylprednisolone