Anesthesia protocol
A total of 90 adult patients were randomly assigned to Group Control
(saline solution) ), Group DEX0.5 (0.5 μg/kg dexmedetomidine), or Group
DEX1.0 (1.0 μg/kg dexmedetomidine). The gastroenterologists,
anesthesiologist and patients, were blinded to the grouping.
Each patient did not receive pre-medication. A 20-G intravenous catheter
was inserted into the right or left antecubital region for fluids and
medicationsHR, MAP, Electrocardiogram, noninvasive systolic arterial
pressure, respiration rate, and peripheral oxygen saturation
(SpO2) were monitored (Philips IntelliVue). All patients
were given oxygen by nasal catheter (the oxygen flow of 3-5 L/min)
during procedure.
A nurse who did not participate in this study diluted the
dexmedetomidine solution to 20 mL. After preoxygenation, patients were
given different doses of dexmedetomidine: saline solution (Group
Control), 0.5 μg/kg dexmedetomidine (Group DEX0.5), or 1.0 μg/kg
dexmedetomidine (Group DEX1.0). The same volume (20 mL) of
dexmedetomidine solutions or saline solution was administered in 5 min.
Then, propofol was given by Graseby 3500 TCI Syringe Pump with the Marsh
parameters. The plasma target-controlled concentration of the first
patient for each group was 2.5 μg/mL. Once the target concentration on
the TCI pump was achieved, gastroenterologists started gastroscopy. In
our endoscopy center, patients underwent gastroscopy followed by
colonoscopy in one anaesthetic treatment. Target-controlled infusion of
propofol is maintained until the end of colonoscopy. A stable sedation
without patient body movements is necessary to enhance the precision and
swiftness of the gastrointestinal endoscopy and enhance the patient
satisfaction and the gastroenterologist satisfaction. The flow chart of
the Dixon’s up-and-down methodology was shown in Figure 7. Whether the
patients were “responsive” is determined by the anesthesiologist who
does not know the grouping and dexmedetomidine dose (saline solution). .
Emergency equipment was always on standby. Ephedrine 6-10 mg was
administered in case MAP dropped blow 60 mmHg or 30% less than the
baseline, and atropine 0.25 mg was given in case HR were lower than 50
beats per minute. Appropriate nitroglycerin was administered in case MAP
were over 120 mmHg. If SpO2 < 92% for more
than 5 seconds, ventilation support was performed by the
anesthesiologist when necessary.