The recovery of pulmonary perfusion after embolism may be influenced by several factors, such as prompt and adequate treatment, recurrence of emboli, and underlying pulmonary pathologic abnormalities. Therefore, an accurate follow-up of patients, both in the early stages after embolization and later on, is clinically helpful.
Previous reports show that perfusion lung scintigraphy, owing to its simplicity and safety, still remains the most suitable technique to assess the severity of embolization and to follow the recovery of pulmonary blood flow under treatment. Our data confirm the foregoing reports and, interestingly, show that pulmonary gas exchange and the chest x-ray film may help in this respect.
In this group of 33 patients, perfusion lung scintigraphy showed the presence of a massive and severe pulmonary embolism. The average number of ULSs, which we chose as an index of the severity of pulmonary embolism, was more than half of the segments normally visible at perfusion lung scintigraphy, corresponding to an average obstruction of the pulmonary arterial tree of 63 percent. Most of the perfusion recovery occurred within the first month of treatment, even though some alterations were still present after six months of treatment. These results suggest the need for performing perfusion lung scintigraphy at fixed times at least up to 30 days after embolization. Viagra Super Active
It is noteworthy that perfusion impairment at perfusion lung scintigraphy correlates well with most parameters of pulmonary gas exchange, both in the acute stage of embolization and during the follow-up period. At the moment of diagnosis, all of the patients showed marked hypoxemia and hvpocapnia. Correspondingly, an increase in P(A-a)()2 and of P(a-A)(XX and a mean value of ViWt% greater than 40 percent were found. These results, observed in the very acute phase of pulmonary embolism, are in agreement witli those of other studies in which the values and limitations of both P(A-a)02 and P(a-A)CQ2, as well as of Vd/Vt%, in the diagnosis of pulmonary embolism have been evaluated. In addition, most of our patients were hyperventilating at diagnosis, as shown by the increase in Ve and the decrease in PaC02. Hyperventilation was still present after one week of treatment. Due to hyperventilation, the level of measured Pa02 would underestimate the actual degree of perfusion impairment. Hence, the Pa02st, ie, Pa02 standardized to a PaC02 of 40 mm Hg or corrected for hyperventilation, was computed.
Thus, Pa02st quantifies more precisely gas exchange impairment, and it gives reliable estimates of perfusion at any level of alveolar ventilation.
The presence of hyperventilation has been reported in most patients with pulmonary embolism. In the present study, hyperventilation correlated significantly with the number of ULSs from diagnosis up to the first month.