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Chapter 8
the simultaneous release of NO from the coronary endothelium after α
2
-stimulation, this
effect is not clinically relevant.
Respiratory
Dexmedetomidine shows no significant effect on hypercapnic or hypoxic respiratory drive
and displays less respiratory depression than other sedatives. However, administration of
opiates, hypnotics, andother sedatives can intensify thepositiveeffects of dexmedetomidine
but also induce negative side effects such as respiratory depression.
Renal
Dexmedetomidine inhibits the release of renin, increases glomerular filtration rate
and excretion of sodium and water, and induces an increased diuresis. It seems that
dexmedetomidine has the potential to reduce perioperatively ischaemia-reperfusion injury.
Gastrointestinal
Α
2
-agonists inhibit the secretion of water and increase the net absorption in the large
intestine. Due to this characteristic, clonidine has even been used in the treatment of
diarrhoea. Production of saliva is also reduced. This can clinically lead to a dry mouth.
Platelets
Α
2
-agonists can – comparable with adrenaline - stimulate the activation of platelets. For that
purpose, a high dose of dexmedetomidine is needed. However, since the normal dosage
of dexmedetomidine decreases the plasma concentration of adrenaline and activates nitric
oxide release, finally a decrease of platelet aggregation is induced.
Applications
ICU
Sedation for ICU patients was the first approved application of dexmedetomidine.
Especially for patients in whom a RASS score of 0 to -3 (mild to moderate sedation) is
pursued, dexmedetomidine has an attractive sedation profile. It provides an adequate level
of sedation, where patients remain arousable to verbal stimulation without respiratory
depression. This enables an easier weaning process and a significantly shorter period of time
to extubation compared with midazolam (3.7 vs. 5.6 days). This was demonstrated in the
SEDCOM study.
7
Patients were treated with a loading dose of 1 μg/kg dexmedetomidine
within 10 min and a continuous maintenance infusion of 1.4 μg/kg/h (EMA approved
dosage) of dexmedetomidine compared with a continuous infusion of midazolam for up