Volumetric capnography as a bedside monitoring of thrombolysis in major pulmonary embolism.

OBJECTIVE: To describe the use of volumetric capnography, a plot of expired CO(2) concentration against expired volume, in monitoring fibrinolytic treatment of major pulmonary embolism. DESIGN AND
SETTING: Two case reports in the emergency department of a teaching hospital. PATIENTS: Two conscious and spontaneously breathing patients (69- and 31-year-old women) with major pulmonary embolism requiring thrombolysis. Decision for thrombolysis was based on the association of right ventricular afterload on echocardiography, with respiratory failure and hypotension in the first patient, and dyspnea and hemodynamically stable parameters in the second one.
INTERVENTIONS: Successive capnographic measurements were performed before, during, and after thrombolysis. Curves of volumetric capnography were obtained from a sidestream gas monitor with flow sensor and an arterial blood gas analysis for CO(2) partial pressure. MEASUREMENTS AND
RESULTS: We calculated late deadspace fraction, previously suggested as the most effective capnographic parameter in the diagnosis of pulmonary embolism. Late deadspace fraction decreased in the two patients, respectively, from 64.4% to 1.1% and from 25.6% to 5.7% after thrombolysis, with a concomitant disappearance of right heart dysfunction signs on echocardiography.
CONCLUSIONS: Volumetric capnography can monitor thrombolysis in major pulmonary embolism. Differences between volumetric capnography technology and the more traditional arterial to end-tidal CO(2) gradient are important to take into account for clinical application.