Hypoxaemia during transoesophageal echocardiography

Abstract

Objectives - To establish the incidence and severity of arterial oxygen desaturation during transoesophageal echacardiography performed under light intravenous sedation; to determine which patients are at greatest risk; and to assess the effects of supplementary oxygen treatment. Design - Prospective study of 150 patients referred for transoesophageal echocardiography. Setting - Echocardiography laboratory in a tertiary cardiothoracic referral centre. Main outcome measure - Transcutaneous arterial oxygen saturation. Results - During transoesophageal echocardiography mean (SD) arterial oxygen saturation (SaO2) fell in 144 of 150 patients (96%) from 95.4%(2.6% to 90.7%(6.3%) (p < 0.001). Significant hypoxaemia, defined as SaO2 < 90%, was found in 27 of 150 patients (18%); in this group SaO2, 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 SaO2, values of 35% and 74%. The principal risk factors for hypoxaemia during transoesophageal echocardiography were mitral valve disease, severe mitral regurgitation, and New York Heart Association symptomatic class III or IV. Conclusions - Transcutaneous oximetry and supplementary oxygen should be available routinely during transoesophageal echocardiography.