FACTORS CONCERNED WITH THE INDUCTION OF TOURNIQUET SHOCK

Abstract

Hyperglycemia develops during the 5 hr. period of tourniquet application to the legs of dogs and continues to be augmented after release in the animal with intact carotid sinuses. When the carotid sinuses are de-nervated, hyperglycemia develops during the period of tourniquet application but is not increased after release. It is concluded that the hyperglycemia after release of tourniquets, as distinct from the hyperglycemia developing during tourniquet application, is dependent upon increased adrenalin discharge. The hyperglycemia that develops during the period of tourniquet application is accompanied by increased rate and strength of cardiac action and by elevated blood pressure. These signs are all more marked when the carotid sinuses are denervated preliminarily and they are interpreted as expressions of sympathetic stimulation. The stimulation of the sympathetic system is a result of pressure exerted by the tourniquets upon underlying nerves, as can be demonstrated by their block with local anesthetics or by their section. The stimulation of the sympathetic system is limited in time and is followed by a longer period of diminished reactivity. Preliminary carotid sinus denervation does not change the outcome of the survival period after release of tourniquets applied to the legs for 5 hrs. A noteworthy observation under these circumstances is the markedly diminished swelling of the legs of dogs with denervated sinuses. When tourniquet application is sufficiently protracted, thrombi develop in the large vessels of the extremities and release is not associated with signs of shock. The length of the period of tourniquet application, even when this is shortened to avoid thrombus formation, definitely influences the symptomatology that follows release. Symptoms of shock most marked with 5 hr. application grow less not only when the period is shorter but also when it is longer. No explanation is available for the lack of symptomatology with longer tourniquet application, when thrombi are absent. Its absence with shorter periods of tourniquet application is more readily understood. No swelling of the legs occurs on release after 2 hrs. of ligation. Even when the extremities are heated in a bath at 47[degree]C. during the 2 hr. period of application, no swelling of the legs follows release. However, shock develops promptly, ends fatally in 2-4 hrs., and is indistinguishable from the syndrome that follows release after 5 hr. ligation at room temp. The possible r61e of infection in these 2 hr. expts. at 47[degree]C. has been excluded. The known increases in serum K and phosphate could not be shown to have major toxic action as detd. by the electrocardiogram.