To determine the effect of transtracheal aspiration (TTA) on cardiac rate and rhythm, we prospectively monitored by electrocardiography 14 cases before, during, and after the procedure. No serious or life-threatening arrhythmias occurred; sinus tachycardia was virtually a routine occurrence. Cardiac rate increased significantly from an average of 96 beats/min before the procedure to an average of 121/min during the procedure (P less than 0.001). The incidence of premature ventricular or atrial contractions did not change significantly before, during, or after the procedure. Before TTA, all patients had PaO2 measurements equal to or greater than 70 mm Hg; none had CO2 retention or an unstable cardiac status. Patients with significant COPD (mean FEV1/FVC% = 48) were not at increased risk for cardiac arrhythmias during or immediately after TTA. Our results imply the following: (1) routine ECG monitoring in patients such as ours undergoing TTA does not appear to be necessary; and (2) premedication with narcotics, sedatives, or atropine does not appear to be warranted.