Pharmacological Interventions to Decompression Sickness in Rats: Comparison of Five Agents

Montcalm-Smith EA, Fahlman A, Kayar SR. Pharmacological interventions to decompression sickness in rats: comparison of five agents. Aviat Space Environ Med 2008; 79:7–13.



Introduction: 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 ∼40 animals that received the drug and ∼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 · 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. Discussion: 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.