Abstract:

Objective  To explore the half effective dose of sufentanil combined with dexmedetomidine for sedation by contrast-enhanced transesophageal echocardiography(cTEE)using a sequential method.

Methods  A prospective research design was adopted, and 26 inpatients aged 18-65 years that were scheduled to undergo cTEE at the Ultrasound Imaging Center of People's Hospital of Shiyan City and classified by American Society of Anesthesiologists(ASA) as grade Ⅰ-Ⅱ were enrolled in this study. For the first patient, the first loading dose of dexmedetomidine was set to 0.8 μg/kg, and the stepped dose was 0.1 μg/kg. The cTEE stress response of the previous patient was used to determine the load of the next patient. When the cTEE stress response of the previous patient was positive, the next patient's load of dexmedetomidine was increased by 0.1 μg/kg. When the cTEE stress response of the previous patient was negative, the load of dexmedetomidine was reduced by 0.1 μg/kg in the next patient. cTEE negative stress response was taken as the inflection point, and so on, until 7 inflection points appeared, when the test was completed. Mean arterial pressure(MAP), heart rate(HR), pulse oxygen saturation(SpO2) and Ramsay sedation score before anesthesia,before probe placement, during probe placement, at 2 min after probe placement, and at the end of the examination were recorded. Left ventricular ejection fraction(LVEF) before and after anesthesia, left ventricular fraction shortening(FS), left ventricular stroke volume(SV)were recorded. Whether the patients could perform a Valsalva maneuver was recorded. Cough and choking, nausea, hypotension, bradycardia and other adverse reactions and complications were recorded.

Results  The half effective dose of sufentanil combined with dexmedetomidine for sedation by transesophageal echocardiography was 0.66 μg/kg(95%CI: 0.59-0.72). HR and MAP before probe placement, during probe placement, at 2 min after probe placement, and at the end of the examination were lower than those before anesthesia(P＜0.05); HR and MAP during probe placement were higher than those before probe placement, at 2 min after probe placement, and at the end of the examination(P＜0.05). The corresponding SpO2 at each time point and the LVEF, FS, and SV before and after anesthesia did not change significantly(P＞0.05).The Ramsay sedation score(2.91±0.58) of all patients after anesthesia inhibited the stress response was between 2 and 4 points in the ideal sedation depth, and they were able to perform a Valsalva maneuver during the examination, and there was no adverse reaction, such as hypoxia, hypotension, or bradycardia.

Conclusion  The half effective dose of sufentanil combined with dexmedetomidine for sedation by cTEE was determined by the sequential method to be 0.66 μg/kg(95%CI: 0.59-0.72).

Key words: dexmedetomidine; echocardiography, transesophageal, half effective dose