Evaluation of tissue perfusion in ischemic legs of dogs by CO2 clearance rate.

Improvement in tissue perfusion following surgically induced ischemia in limbs of dogs was experimentally evaluated to clarify the improvement of hemodynamics following walking exercise in chronic, peripheral arterial occlusive diseases. With the use of a computer system in conjunction with medical mass spectrometry, the local tissue perfusion rate was calculated on the basis of the clearance curve of tissue partial pressure of CO2 following electrical stimulation of the ischemic leg to simulate exercise. Ischemia was created in the leg by ligation of the proximal and peripheral arteries. In one month, intermittent claudication improved in accordance with improvement in muscle tissue perfusion. Angiographic evidence of distal runoff became visible six months after surgery, indicating that tissue perfusion played an important role in peripheral hemodynamics. The local tissue perfusion rate improved from 9.51 +/- 2.62 ml/100 g/min to 12.41 +/- 2.42 in one month, to 14.59 +/- 3.19 in three months, to 15.11 +/- 3.24 in six months and to 17.19 +/- 2.63 in twelve months. The improvement of ischemic symptoms following long-term exercise is attributed to improvements in tissue perfusion or collateral circulation.