Objective    To observe the changes of oxygen dynamics in patients with chronic obstructive pulmonary disease (COPD) and analyze its clinical importance.     Methods    The Swan-Gans catheters combined with arterial blood gas analysis were used to measure the parameters of blood and oxygen dynamics in 166 patients suffering from COPD during the period of 1977-1984. Those complicated pulmonary h

ypertension (PH) or respiratory failure (RF)

during the exacerbation or remission period

and the dead or the survived were comparatively studied within 20 years of follow-up (from 1984 to 2004).     Results    Totally 116 out of 166 patients died with death rate of 69.9%. The mean pulmonary arterial pressure (mPAP)

cardiac index (CI)

total pulmonary vascular resistance (TPR)

oxygen delivery (DO

2

) were within normal ranges

and the oxygen consumption(VO

2

) and oxygen uptake rate(O

2

-ER) kept at relatively low levels in patients with simple COPD or in a stable period or still alive; whereas in patients with COPD concurrent PH

RF

or in an exacerbation period or died

CI

DO

2

VO

2

O

2

-ER were significantly lowered and mPAP and TPR were significantly increased (P0.05 or 0.01).After isoket intervention

the CI

DO

2

and O

2

-ER in patients with COPD associated with PH were significantly increased and the mPAP

TPR decreased.     Conclusion    Patients suffering from COPD without PH

RF or in a stable period or still alive have a low level of balance for oxygen delivery and demand

and maintain a non-oxygen dependent status. When COPD exacerbated or associated with PH or RF

or patients died

this balance will be disturbed and patients are in oxygen-depended status. Vasodilators such as isoket can increase oxygen delivery.  Extreme diminishment of oxygen supply and consumption are probably the dangerous factors responsible for the death of COPD.