Pulmonary artery pressure versus pulmonary capillary wedge pressure and central venous pressure in shock

Evidence is presented from 43 dogs and 30 patients that under conditions of severe hemorrhagic, traumatic or septic shock, there may be partial obstruction of the pulmonary microcirculation due to disseminated intravascular coagulation (DIC) particularly in the pulmonary venules. This may cause the left atrial pressure to fall and the pulmonary artery pressure to rise, in some cases drastically. Pulmonary edema may result. This dangerous rise in pulmonary artery pressure is not reflected by the wedged pulmonary artery catheter which will monitor only the status of the left heart. Central venous pressure (CVP) may remain within normal limits even after pulmonary artery pressure has risen to dangerous levels with the development of pulmonary edema. It is only with right ventricle failure against the high pulmonary pressure that CVP rises. It is concluded that pulmonary artery pressure measurements are very important in monitoring intravenous fluid administration in severe shock. Wedged pulmonary artery pressures monitor the left heart but may be misleading if taken alone. Central venous pressure gives a delayed response to fluid overload.