Influence of hypothalamic hyperphagia on tolerance of lung to explosive decompression.

A study was made of the effect of hypothalamic hyperphagia on the tolerance of lung to explosive decompression in male Long-Evans rats. The control and hypothalamic hyperphagic rats were explosively decompressed together from 1 atm to an ambient pressure of 30 min Hg in 0.04s. The hypothalamic-lesiones rats gained from 252 g average weight to 460 g, a 82% gain. The respective figures for the controls. were from 248 g to 336 g and 36%. It was also observed that a considerable amount of fat was accumulated between pleura and lungs in experimental animals. The average accumulation of fat between pleura and lungs in experimental rats was 3.23 g, while the value of the control group was only 0.42 g. The difference was statistically significant. Such an increase of fat accumulation in the thoracic cage could decrease the tidal volume. The severity of decompression-induced pulmonary hemorrages might thus be decreased. On the other hand, it also seems possible that the soft fat cushion between pleura and lungs might damp the bruising of the pulmonary tissue against the resistant thoracic wall to a certain extent, thus resulting in a decreased susceptibility to decompression-induced lung damage. Besides , the mortality in obese rats undergoing explosive decompression was also significantly lower than that of the controls