Nitrous oxide inhalation for transoesophageal echocardiography: an alternative to benzodiazepine sedation?

AIMS Transoesophageal echocardiography (TEE) is usually performed using benzodiazepine sedation, which is a limiting factor for elderly patients or those with respiratory insufficiency. Kalinox, an equimolar mixture of nitrous oxide and oxygen, with no depressive respiratory action and fast reversible effects, seems ideally suited for performing TEE but has never been evaluated. The aim of the present study was to evaluate the TEE feasibility and efficiency using Kalinox compared with the standard care using benzodiazepine. METHODS AND RESULTS We prospectively enrolled 80 consecutive patients referred for TEE. In the 35 first patients, TEE was performed using intravenous benzodiazepine (Midazolam) and in the 45 last patients using Kalinox (nasal delivery). Pain and tolerance induced by the examination were evaluated on a 0-10 scale. Remembrance of the examination by the patient and quality of the TEE by the operator were also evaluated. All TEEs were performed by the same experienced operator. TEE duration was not different (6 +/- 3 vs. 7 +/- 4 min, respectively, P = 0.57). Patients in the Kalinox group felt TEE to be more difficult (P = 0.005) and remembered the procedure more clearly (P < 0.0001) but pain experience was not different (7 vs. 9% had a pain score >or=5, respectively, P = 0.75). Percentage of patients who agreed to have a second TEE if necessary was slightly lower (77 vs. 94%, respectively, P = 0.04). The operator judged TEE quality satisfactory in similar proportions (76 vs. 68%, respectively, P = 0.44). CONCLUSION These preliminary results show that TEE using Kalinox is feasible, provides similar pain relief despite more discomfort for the patient, and acceptable conditions for the operator. Thus, Kalinox use could be considered as an alternative to benzodiazepine sedation for patients intolerant to benzodiazepines such as elderly or respiratory-insufficient patients.