HYPOXEMIA DURING TRANSESOPHAGEAL ECHOCARDIOGRAPHY

Objectives-To establish the incidence and severity of arterial oxygen desaturation during transoesophageal echocardiography performed under light intravenous sedation; to determine which patients are at greates t risk; and to assess the effects of supplementary oxygen treatment. D esign-Prospective study of 150 patients referred for transoesophageal echocardiography. Setting-Echocardiography laboratory in a tertiary ca rdiothoracic referral centre. Main outcome measure-Transcutaneous arte rial oxygen saturation. Results-During transoesophageal echocardiograp hy mean (SD) arterial oxygen saturation (Sao(2)) fell in 144 of 150 pa tients (96%) from 95.4%(2.6%) to 90.7%(6.3%) (p < 0.001). Significant hypoxaemia, defined as Sao, < 90%, was found in 27 of 150 patients (18 %); in this group Sao, fell from 92.9%(3.5%) to 81.8%(9.6%) (p < 0.001 ), but rose rapidly on oxygen to 95.5%(2.4%) (p < 0.001). Two patients became profoundly hyperaemic with SaO(2) values of 35% and 74%. The p rincipal risk factors for hypoxaemia during transoesophageal echocardi ography were mitral valve disease, severe mitral regurgitation, and Ne w York Heart Association symptomatic class III or IV. Conclusions-Tran scutaneous oximetry and supplementary oxygen should be available routi nely during transoesophageal echocardiography.