A New Measure of Decompression Sickness in the Rat

Abstract

In this study we assessed the reliability of a tilting-board grip score as a measure of decompression sickness in rats. In experiments using a hyperbaric compression/decompression protocol, rats were observed for signs of decompression sickness and their grip strength measured on a tilting particle board hinged to a metal frame. Angles at which rats lost grip were converted to gravitational vectors. Decreased mean grip scores following decompression were fitted to a logistic regression model with strain, age, and weight. Decrease in grip score was significantly associated with observed decompression sickness (P = 0.0036). The log odds ratio for decompression sickness = 1.40 (decrease in grip score). In rats with no decrease in mean grip score there was a 50% probability of decompression sickness (pDCS). This increased steadily with decreases in mean grip score. A decrease of 0.3 had a 60% pDCS, a decrease of 0.6 had a 70% pDCS, and a decrease of 2.1 had a 95% pDCS. The tilting board grip score is a reliable measure of the probability of decompression sickness.

A ternary model of decompression sickness in rats

“…Again, an appropriate weighting for sDCS may have an appreciable effect upon this test. Overall, the relationship between DCS and weight, sex and strain have all been experimentally confirmed in our laboratory, 23,38 and the relationship between DCS and Max1, Max1b and Bubble3 are in accord with what is known of DCS, namely that ascent rate and supersaturation are key factors, and that saturation in the rat occurs at around 60-90 mins.…”

“…Furthermore, we experimentally confirmed that DCS incidence in this compression/decompression profile elicited similar incidence of DCS between Wistar and Sprague-Dawely. 23 This should be reassuring to the scientific community who rely on previous research utilising either one strain or the other. That exercise was not significant may be explained by the inclusion criteria that at least one rat must be represented in each outcome state.…”

“…Recently a promising grip-score test was found significantly associated (p=0.004) with observable signs of what was assumed to have been DCS. 23 Unexpectedly, based upon the correlation between loss of grip strength and perceived DCS, Buzzacott et al discovered the post-decompression probability of any asymptomatic rat having DCS was 0.5. The precise diagnosis of DCS in the rat, therefore, remains a desirable goal.…”

Angiotensin Converting Enzyme Inhibitor Has a Protective Effect on Decompression Sickness in Rats

“…Other studies using an ED-50 rat model have classified their outcome variables as DCS vs. No-DCS, whereby the marginal cases were combined with the dead, or the classification was Dead vs. Not-Dead, where the marginal cases were combined with the asymptomatic. In this study the ternary classification of “No DCS” (no symptoms), mild “DCS” (with at least one symptoms excluding death within the observation period) or severe DCS (“Death” within 1 h) was retained to maximize statistical power, as described by Buzzacott et al ( 2014 ).…”

Effect of angiotensin II on irradiation exacerbated decompression sickness

“…DCS was diagnosed by three observers who were unaware of the treatment. According to the evaluation criteria of decompression sickness 23 , 24 , the rats were diagnosed as DCS if any one of the symptoms of scratching, sluggishness, tachypnea or dyspnea, cyanosis, paralysis, convulsions, and death occurred after treatment. Severe DCS was defined as having at least one symptom, including paralysis, dyspnea, convulsions, and death.…”