Sidenafil Pre-Treatment Promotes Decompression Sickness in Rats

Abstract

Vascular bubble formation after decompression contributes to endothelial injuries which form the basis for the development of decompression sickness (DCS). Nitric oxide (NO) is a powerful vasodilator that contributes to vessel homeostasis. It has been shown that NO-releasing agent may reduce bubble formation and prevent serious decompression sickness. The use of sildenafil, a well-known, phosphodiesterase-5 blocker, which act by potentiating the vasodilatory effect on smooth muscle relaxation, has never been studied in DCS. The purpose of the present study was to evaluate the clinical effects of sildenafil pre-treatment on DCS in a rat model. 67 rats were subjected to a simulated dive at 90 msw for 45 min before staged decompression. The experimental group received 10 mg/kg of sildenafil one hour before exposure (n = 35) while controls were not treated (n = 32). Clinical assessment took place over a period of 30 min after surfacing. At the end, blood samples were collected for blood cells counts and the level of circulating bubbles in the right cavities was quantified. There were significantly more manifestations of DCS in the sildenafil group than in the controls (34.3% vs 6.25%, respectively, p = 0.012). Platelet count was more reduced in treated rats than in controls (−21.7% vs −7%, respectively, p = 0.029), whereas bubble grades did not differ between groups. We concluded that pre-treatment with sildenafil promotes the onset and severity of neurological DCS. When considering the use of phosphodiesterase-5 blockers in the context of diving, careful discussion with physician should be recommended.

Colonic Fermentation Promotes Decompression sickness in Rats

“…We used a staged decompression, capable of causing ischemic impairments of the spinal cord with variable severity in the rat 31 32 . This model therefore makes it possible to move closer to the DCS observed in humans.…”

A ternary model of decompression sickness in rats

“…Treatments and/or risk factors are then typically evaluated by the degree of difference in the proportion of animals that are diagnosed with DCS following decompression. 1 DCS in the rat has been variously defined and diagnostic criteria include survival time, [2][3][4] observable signs such as walking difficulties, 3,[5][6][7][8][9][10][11][12][13][14] paralysis, [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] rolling in a rotating cage, 5-9, 12, 13, 15, 16, 20 twitching/convulsions 5-9, 12, 13, 15, 16 and/or respiratory distress 5-7, 9-11, 13, 14, 17-19 .…”

“…10,21,22 Only rarely have objective measures been correlated with subjective observer agreement. Recently a promising grip-score test was found significantly associated (p=0.004) with observable signs of what was assumed to have been DCS.…”

Endothelia-Targeting Protection by Escin in Decompression Sickness Rats

“…This possibility remains to be tested. The vasoconstrictor property of escin which may result in limiting inert gas loading during hyperbaric exposure, and delaying the removal during and after decompression, may have paradoxical effects on its protection against DCS31. Although in the present study no adverse effect was observed, the contractile effect of escin should be considered before recommending escin for DCS prevention.…”