Baylor University Medical Center Proceedings January 2014, Volume 27, Number 1 | Page 10

53.6%
48.7%

50
49

48.2%

49
48

40.4%

6.0%
0

3.1%

0
<10

10-18

19-24

Respiratory Rate

>24

Placebo
Dexmedetomidine

Figure 4. Respiratory rates between subjects randomized to placebo compared
to intravenous dexmedetomidine.

Mean tcpCO2 (mm Hg)

Percent

48

46
46

45
45

Dexmedetomidine
44
44
43
43

42
42
41
41
40

have compromised respiratory function. Thoracotomy patients
receiving opioids via a PCA pump postoperatively are at high
risk for developing respiratory depression. A recent study by
Overdyk et al found respiratory depression rates in postoperative patients with a PCA pump that were higher than previously
reported (6).
Dexmedetomidine provides a unique type of sedation in
which patients appear sleepy but are easily aroused. There is
no significant respiratory depression even at high doses, and
the drug possesses anxiolytic and moderate analgesic effects
(24). This opioid-sparing property together with anxiolysis and
sedation could provide analgesia and comfort to postthoracotomy patients and potentially reduce the number and severity
of opioid-induced side effects. By modulating the release of

Placebo

47
47

4 0

2

6

4

6 8

8

10
10

12

12
14

16

1418

20 16 22

18
24

Study drug infusion hour

Figure 5. Transcutaneous carbon dioxide results of subjects randomized to
placebo compared to intravenous dexmedetomidine.

catecholamines, dexmedetomidine decreases sympathetic tone
and attenuates the stress response to surgery and anesthesia.
Some data suggest that dexmedetomidine is protective of major
organs and can prevent acute brain dysfunction or delirium
postoperatively (25–38). This may be of great significance
in this often elderly and high-risk cardiac group of patients.
However, although dexmedetomidine appears to be well tolerated, there have been reports of hypotension, bradycardia,
and cardiac arrest associated with its administration (39–41).
As the drug modulates the release of
catecholamines, vagus nerve activity
is left unopposed and the patient reTable 3. Adverse events in subjects randomized to dexmedetomidine or placebo
quiring catecholamine support is in a
DexmedeWithdrawn from study
critical situation. Therefore, signs of vatomidine†
prior to randomization†
Adverse event
Placebo†
Total
gal overactivity should be treated with
Nausea
7
3
—
10
atropine or glycopyrrolate, and care
Headache
1
1
—
2
should be given when considering the
administration of dexmedetomidine to
Pruritus
3
—
—
3
hypovolemic patients or patients in an
Constipation
2
1
—
3
early shock situation.
Fever
2
1
—
3
This pilot study addressed the
Generalized weakness
1
2
—
3
need for adequate postoperative an1
4
—
5
Systolic blood pressure <90 mm Hg∗
algesia while at the same time decreas†
Systolic blood pressure <90 mm Hg
1
2
—
3
ing the risk for respiratory depression
and other untoward side effects by
Heart rate <50 bpm
2
0
—
2
reducing opioid use. In this study, no
Heart rate >110 bpm
3
1
—
4
patients were found to have a respiraPotassium <3.6 mEq/L
—
1
—
1
tory rate <10, although this was an
Blood glucose >110 mg/dL
—
1
—
1
intermittent measurement and brief
Cardiac arrest/death
—
—
1
1
transient changes in respiratory patMultiple organ dysfunction syndrome
—
—
1
1
terns are likely and could have been
missed. The patients in this study
Stokes-Adams syndrome
—
—
1
1
had increased respiratory rates >50%
Total
23
17
3
43
of the time across both groups, with
∗Required study drug interruption.
†Subjects withdrawn from study due to concurrent beta-blocker, pneumonia, sepsis, and volume depletion.
the percentage of the placebo group
at >18 breaths per minute higher than

8

Baylor University Medical Center Proceedings

Volume 27, Number 1