Single administration of warfarin at 0.1mg/kg was carried out at an early stage after cardiac operation, and changes in the blood vitamin K levels, blood coagulation factors and the blood warfarin levels within 24 hours of administration were evaluated to determine an ideal mode of initiating the administration and the initial dose in warfarin therapy at an early postoperative stage. The study group consisted of 30 postoperative cardiac cases, and 20 healthy individuals as controls. The results showed that anticoagulant effects cause close to the therapeutic range within 24 hours of administration of oral warfarin therapy in prothrombin time of the postoperative cases. As regards the blood vitamin K levels, both vitamin K₁ and K₂ levels were more depressed in the subjects than in the control group. Differences in the vitamin K level seemed to play a key role in the difference in anticoagulability between the two groups. It was thus implied that the risk of an abrupt decline in coagulability and a decrease in the level of vitamin K parallels the starting level of warfarin instituted in the wake of a cardiac operation. To conclude, safe and effective warfarin therapy should be started at a 0.1mg/kg dosage level at an early stage after the cardiac operation.

The difference in cardiopulmonary response between supine exercise and sitting exercise was assessed by the following protocols.
1) Cardiopulmonary exercise testing utilizing the ramp protocol with a bicycle ergometer (20 W/min) was performed by nine healthy Japanese men (mean age, 19.9 yr) in a sitting and a supine position. Oxygen uptake, heart rate and blood pressure were measured during the test. Blood was sampled in order to measure noradrenaline (NA) and angiotensin II (ANG II) in the resting control state and immediately after exercise.
2) Single-level exercise testing at 100 W was performed on another day. The cardiac index (CI) was computed from the cardiac output, which was measured using the dye-dilution method in the resting control state and during exercise.
The results were as follows:
1) Heart rate and blood pressure during exercise had a tendency to be lower in the supine position compared to the sitting position, although not significantly.
2) Anaerobic threshold (AT) was lower in the supine position than in the sitting position exercise, (18.3±2.6 ml/kg/min and 21.7±1.9 ml/kg/min, respectively) .
3) NA and ANG II in the supine position were slightly lower than in the sitting position.
4) At rest, the CI in the sitting position was significantly less than in the supine position; however, the CI during the 100 W exercises was the same in both the supine and sitting positions.
It is concluded that blood flow to active muscle during 100W exercise is lower in the supine than in the sitting position. This is thought to be due to changes in blood redistribution and lowered blood flow to active muscle in the supine position, creating a lower AT.