الفهرس 
Pharmacology of DexmedetomidineOnly 14 pages are availabe for public view
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Abstract
Emergence agitation during the immediate postanesthetic
period is common. It may lead to serious
consequences for the patient, such as injury, increased pain,
hemorrhage, self-extubation, and removal of catheters, and it
can necessitate physically or chemically restraining the patient.
Emergence agitation is also disturbing to anesthesiologists and
recovery room staff and can lead to increased hospital costs.
Many patients need sedation, particularly those who
require mechanical ventilation, but inappropriate or excess
sedation can have unintended consequences. In addition to
increased length of stay and failure to wean from the
ventilator, excessively sedated patients can develop prolonged
cognitive impairment and delirium.
Discontinuation of mechanical ventilatory support
represents a milestone in the progression to patient recovery in
the intensive care unit (ICU). Despite advances in mechanical
ventilation and respiratory support, the science of determining
if the patient is ready for extubation is still very imprecise. As
a result, reported re-intubation rates vary from 2% to as high as
25%, depending on the ICU population studied.
Summary
90
Several clinical trials have compared propofol with
midazolam in patients requiring sedation for general medical
conditions, after general or cardiac surgery and following
general trauma or head injuries. The quality of sedation
achieved with propofol was at least as good as that achieved
with midazolam, and in almost all studies the rate of recovery
(time to spontaneous ventilation or time to extubation) was
significantly faster with propofol.
Dexmedetomidine has analgesic and sedative properties.
Its use is not associated with respiratory depression despite
profound levels of sedation. Because of analgesia sparing,
sedation and lack of respiratory depression, dexmedetomidine
may prove useful in the postoperative period for patients
having major surgical procedures that are associated with
significant pain.
Despite profound sedative properties, dexmedetomidine
is associated with only limited respiratory effects, even when
dosed to plasma levels up to 15 times of those normally
achieved during therapy, leading to a wide safety margin
.Hypercapnic arousal is preserved, and the apnea threshold is
actually decreased. In contrast to infusions of opioids,
benzodiazepines, or propofol, dexmedetomidine can safely be
infused through tracheal extubation and beyond.
Summary
91
This study compared the effect of dexmedetomidine and
propofol to treat emergence agitation and facilitate extubation on
120 adult patients of ASA II and III physical status undergoing
pelvi-abdominal surgery and requiring postoperative mechanical
ventilation in the surgical ICU for maximum duration of 48
hours postoperatively.After their arrival inubated to the ICU,
the patients were immediately artificially ventilated with
synchronized intermittent mandatory ventilation (SIMV) with
pressure support mode, when they could open their eyes on
command,they were allocated into two groups ,60 patients in
each according to the drugs used, by the single blind
technique.
- Group ’D’ received a loading infusion dose of
dexmedetomidine 2.5 μg/kg/h over 10 minutes followed
by maintenance infusion at a rate of 0.2-0.5 μg/kg/h into a
peripheral vein, with the dosage adjusted to achieve the
desired level of sedation (RASS -2 to 0).
- Group ’P’ received Propofol undiluted as a bolus dose of
1 mg/kg initially, followed by an infusion of 1-2 mg/kg/h,
with the dosage adjusted to achieve the desired level of
sedation (RASS -2 to 0).
Summary
92
The following parameters were monitored during the
study: vital data, sedation score, pain scale and total analgesic
consumption, time to extubation, length of ICU stay, and
occurrence of any side effects from the drugs.
The study showed that postoperative dexmedetomidine
sedation after major pelvi-abdominal surgeries for intubated
and mechanically ventilated patients reduces emergence
agitation, facilitates extubation and weaning from mechanical
ventilation, reduces the opioids requirements , produces
moderate sedation which is beneficial for better patients’
communication and pain expression , and reduces the ICU
stay.