Pathophysiology, diagnosis and treatment of intermittent claudication in patients with lumbar canal stenosis

Figure 4 Changes of intraradicular blood flow, partial oxygen pressure and conduction velocity after Aorta (A) or inferior vena cava (B) clamp. Immediately after Aorta clamping, blood pressure in the femoral artery dropped to 26-40 mmHg and meantime, central venous pressure was slightly elevated. When the vena cava was clamped, central venous pressure increased to about 4 times of the pressure before clamping and blood pressure in the femoral artery was reduced by half. The blood flow in the seventh posterior nerve root due to Aorta and vena cava clamping fall to 50% to 60% of the blood flow before clamping in the ischemic model (^aP < 0.05) and to about 20% in the congestion model (^aP < 0.05). The changes of partial oxygen pressure (PO₂) in the nerve root indicated a similar tendency to blood flow, 50% to 60% drop in the ischemic model (^aP < 0.05) and 20% to 40% drop in the congestion model. Conduction velocity of the nerve root diminished by 40% to 50% in the ischemia model (^aP < 0.05) and 10% to 20% in the congestion model. After release of clamping, both arterial and venous pressures quickly returned to the pressure before clamping. The intraradicular blood flow in the congestion model was restored within 1 h. The intraradicular blood flow in the ischemic model, however, did not recover and stayed at the reduced level (^aP < 0.05). Intraradicular PO₂ recovered completely in both models. The drop of conduction velocity returned almost completely within one hour after release of clamping. Reproduced with permission from Kobayashi et al[42].