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. 2018 Jul-Aug;33(4):404–417. doi: 10.21470/1678-9741-2017-0253

Table 3.

Characteristics of included trials.

Study Design Fixed TRT (drug) for all groups Postoperative pain outcome assessment and time points Authors conclusion / DEX reported complications
Dong et al.[14], 2017 Two parallel groups, N= 60
G1: PCIA (n=30)
G2: DEX 4 mcg/kg added to PCIA (n=30)
Surgery (n of CO, n of DEX): elective major open thoracotomy operations include esophageal neoplasia resection (16, 17), lobectomy (6, 7), pneumonectomy (1, 2), mediastinal mass (2, 2), and pneumothorax (5, 2)
INT duration: the first 48h postop period
Mean of age: G1=57.3 G2= 55.4, range=32-65 y
M/F: 19/31
PCIA program:
Drug: SUF 3.0 mcg/kg plus 8mg ondansetron
Loading: 20 ml
On demand: 2 ml
Lock-out: 10 min
Background: 4 ml
Outcomes: SUF consumption in the 48h postop period, the mean of pain intensity, the number of PCIA self-administer and meperidine injection
Interval: 2, 6, 12, 24, 36 and 48h postop period
Scales: VAS
The combination of DEX and SUF in PCIA reduces SUF consumption, the pain intensity, and supplemental analgesic requirements, while maintaining a good hemodynamic stability.
DEX reported complications: bradycardia, hypotension, over sedation
Dutta et al.[15], 2017 Two parallel groups, N= 30
G1: Standard drug (n=15)
G2: a bolus of DEX 1 mcg/kg over 3 to 5 minutes followed by an infusion of 0.2 mcg/kg/hour added to standard drug (n=15)
Surgery (n of CO, n of DEX): elective lung surgeries via anterolateral or posterolateral thoracotomy including lobectomy (2, 8), pneumonectomy (5, 5), cyst excision (5, 0), decortication (2, 2), and bullectomy (1, 0)
INT duration: the first 24h postop period
Mean of age: G1=34.4 G2= 42.1, range=18-70
M/F: 20/10
Standard drug:
A bolus of 15 mL of 0.75% ROPI over 3 to 5 minutes, followed by an infusion of 0.2% ROPI at 0.1 mL/kg/h
Thoracic paravertebral block by lignocaine 2% (3 mL) with adrenalin up to 72 hours after surgery
Outcomes: Intraoperative anesthetic drug requirement, pain scores,  rescue analgesic use requirement, and incidence of pain syndrome in 2 months
Intervals:1, 2, 3, 4, 8, 12, 16, 20, and 24h postop period
Scales: VAS
Paravertebral DEX administration is associated with lower number of rescue analgesia, morphine required, total intraoperative fentanyl dose, propofol induction dose, and lower postop pain in 1, 2, 4, and 8 hours.
DEX fails to lower the incidence of post-thoracotomy pain syndrome.
DEX reported complications: bradycardia, hypotension, over sedation
Jabbary Moghaddam et al.[16], 2016 Two parallel groups; N=104
G1: IV infusion of DEX 0.5 mcg/kg/h (n=50)
G2: NS (n=54)
Surgery (n of CO, n of DEX): elective CABG
INT duration: from the initiation of anesthesia until extubation in the ICU
Mean of age: G1=57.3, G2= 55.4
M/F: 71/33
None Outcomes: the NRS score after surgery and the incidence of postop pain by telephone interview
Intervals: two months
scale: NRS and BPI
The incidence of postop was significantly lower in the DEX group than that of the control group.
Pre-emptive intraoperative DEX may reduce pain
DEX reported complications: not reported
Cai et al.[17], 2016 Two parallel groups; N= 94
G1: DEX at a loading dose of 1 mcg/kg for 10 minutes, followed by continuous infusion at 0.5 mcg /kg/h (n=46)
G2: NS (n=48)
Surgery (n of CO, n of DEX): thoracic surgeries including thoracoscopic lobectomy (12, 10), open thoracic lobectomy (4, 6), incision of esophageal cancer (32, 30)
INT duration: the first 48h postop period
Mean of age: G1=54.6 G2= 55.4, range=18-65
M/F: 94/0
PCIA program:
Drug: SUF 0.8 mg/mL
Loading: 2 mL
On demand: none
Lock-out: 5 min
Background: a 4-hour limit
of 30 to 40 mL of SUF
Outcomes: The mean of pain at rest and with coughing and dosage of SUF during surgery
Intervals: at arrival, 1, 4h, and every 4h thereafter until the 48h postop period
Scales: NRS
Intraoperative DEX can reduce the opioid requirement and pain intensity, as well as reduce the cumulative dosage of SUF, NRS at rest, and NRS with coughing scores.
DEX reported complications: bradycardia
Priye et al.[18], 2015 Two parallel groups; N= 64
G1: IV infusion of DEX 0.4 mcg/kg/h for 12h without a loading dose, (n=32)
G2: NS (n=32)
Surgery: elective cardiac surgery using cardiopulmonary bypass (CPB) including coronary artery bypass graft, valve surgery, and atrial septal defect closure. (Note: the number of subjects in each category was not identified by authors)
INT duration: Intraoperative until the first 24h postop period
Mean of age: G1=41.4 G2= 45.1, range= over 18
M/F: 33/31
None Outcomes: Postop pain and total fentanyl consumption Intervals: 6, 12, 18, and 24h Scales: VAS DEX is associated with lower pain score at 0, 6, 12, 18 and 24h postop period and fewer fentanyl consumption than normal saline. Also, DEX could reduce the incidence of delirium.
DEX reported complications: without significant complications
Ren et al.[19], 2015 Three parallel groups; N= 125
G1: SUF 0.02 mcg/kg/h, (n=41)
G2: SUF 0.02 mcg/kg/h plus DEX 0.02 mcg/kg/h each (n=41)
G3: SUF 0.02 mcg/kg/h plus IV infusion of DEX 0.04 mcg/kg/h (n=43)
Surgery (n of CO, n of DEX1, 2): thoracic surgeries including thoracotomy in esophageal (one incision) (35, 34, 36) and thoracotomy in cardiac cancer (6, 7, 7)
INT duration: the first 72h postop period
Mean of age: G1=59.8, G2= 59.9, G3=60.5, range=35-65
M/F: 125/0
PCIA program:
Drug: SUF 0.8 mg/mL
Loading: 2 mL
On demand: none
Lock-out: 5 min
Background: 2 ml/h, 4h limit of 40 ml
Intraoperative DEX: a small bolus of 0.5 mcg/kg then reduced to 0.5 mg/kg/h
Outcomes: cumulative amount of self-administered SUF and the postop pain intensity scores both at rest and with coughing
Intervals: 1, 4, 8, 16, 24, 48, and 72h
Scales: NRS
Addition of DEX 0.04 mcg/kg/h to SUF improves the analgesic effect of SUF and is associated with greater patient satisfaction without side effects. This combination could decrease the total dosage of SUF during the first 72h after surgery.
DEX reported complications: without significant complications
Ramsay et al.[20], 2014 Two parallel groups; N= 38
G1: IV infusion of DEX 0.1 to 0.5 mcg/kg/h, (n=19)
G2: NS (n=19)
Surgery: major open lateral thoracotomy (Note: sub-categories of thoracotomy has not been identified by authors)
INT duration: 18 to 24h postop period
Up to 24h after that (42-48h postop)
Mean of age: G1=61, G2= 56, range=18-85
M/F: 15/23
PCIA
Drug: MO
Protocol: not reported, but the two groups were similar in the types of PCA pumps and supplemental opioids used
Intraoperative:
DEX at 0.2 to 0.5 mcg/kg/h without bolus until 30 minutes prior to transfer to the telemetry unit
Outcomes: the amount of self-administered opioid medication and average pain scores
Intervals: 24h after ICU discharge and 24 to 48h postop
Scales: VAS
In comparison with normal saline, DEX is associated with lower morphine consumption, however, the mean pain scores between DEX and normal saline groups were similar.
DEX reported complications: hypotension, bradycardia
Abdel-Meguid[21], 2013 Two parallel groups; N= 30
G1:  DEX at 0.5 mcg/kg/h after the induction of anesthesia, that reduced to 0.3 mcg/kg/h on admission in the ICU and continued for 12h post extubation (n=15)
G2: NS (n=15)
Surgery: elective coronary artery surgery using OPCAB technique
INT duration: The first 12h post extubation
Mean of age: G1=55, G2= 52
M/F: 23/7
MO for postop pain management Outcomes: The median of postop pain and total dose of MO
Intervals: 2, 4, 6, 8, 10, 12h postop
Scales: VAS
DEX showed a better pain control, a lower consumption of narcotics and earlier extubation time.
DEX reported complications: not reported
Elhakim et al.[22], 2010 Two parallel groups; N= 50
G1: DEX 1 mcg/kg plus bupivacaine 0.5% via epidural catheter (n=25)
G2: bupivacaine 0.5% via epidural catheter (n=25)
Surgery (n of CO, n of DEX): elective open thoracotomy for lung surgery with one-lung ventilation including right lobectomy (12, 11), right pleurectomy (7, 7), and right pneumectomy (6, 7)
INT duration: after induction of general anesthesia until the first 24h postop period
Mean of age: G1=52, G2=50, range=43-54
M/F: 50/0
Drug:
IV crystalloids colloids and fentanyl bolus dose were added to the epidural medication
Outcomes: Postop pain scores, and postop analgesic use requirement Intervals: at 6, 12, 18, and 24h after surgery
Scales: VRS
Epidural use of DEX decreases the anesthetic requirements and improves postoperative analgesia as well as shorter the ICU stay
DEX reported complications: without significant complications
Ghandi et al.[23], 2005 Two parallel groups; N=100
G1: MO 0.2 mg via PCIA at 4 ml/h (n=50)
G2: DEX 0.2 mcg/kg via PCIA (n=50)
Surgery: candidates for open cardiac surgery
INT duration: after surgery until the first 24h postop
Mean of age: G1=66.7, G2= 65.4, range=54-81
M/F: not reported
PCIA, but the protocol not reported by authors Outcomes: The mean of postop pain intensity and intravenous MO consumption
Intervals: 2, 4, 6, 8,10,12, 14, 16 and 18h postop
Scale: VAS
DEX is associated with lower pain score in the 2, 4, 6, 8, 10 and 12h postop periods. Male patients experienced lower pain than female in the DEX group. DEX reduced the IV MO consumption during ICU stay. DEX shortened the intubation time.
DEX reported complications: without significant complications
Wahlander et al.[24], 2005 Two parallel groups; N= 28
G1: IV loading dose of DEX 0.5 mcg/kg over 20 minutes, followed by continuous IV infusion at 0.4 mcg/kg/h, (n=14)
G2: NS (n=14)
Surgery: elective thoracotomy for wedge resection, lobectomy, or pneumonectomy (Note: the number of subjects in each category was not identified by authors)
INT duration: the first 24h post ICU
Mean of age: G1=67.7, G2= 65.7, range= over 18
M/F: 12/16
In the operating room, a TEC loaded using 3 mL of 1.5% lidocaine-epinephrine mixture.
PCEA program:
Loading: 3 mL 0.125% (3.75 mg) bupivacaine,
Lock-out: 20 min
Background: 4-hour limit of 30 mL 0.125% (37.5 mg) bupivacaine
Outcomes: need for additional epidural bupivacaine administered by PCEA and the requirement for supplemental opioids (fentanyl)
Intervals: at admission to SICU or PACU (zero time point) and then in  1, 2, 3, 4, 12, 16, and 24h postop periods
Scales: VAS
IV DEX has beneficial analgesic effects on post-thoracotomy pain when using as an addition to a thoracic epidural infusion of 0.125% bupivacaine.
It is unable to decrease the PCEA requirement, but is able to decrease the requirement for opioids and likelihood of respiratory depression
DEX reported complications: hypotension and bradycardia
Venn et al.[25], 1999 Two parallel groups; N= 98, cardiac (n=81)
G1: IV DEX at a loading dose of 1 mcg/kg over 10 min followed by a maintenance infusion rate of 0.2-0.7 mcg/kg/h, maximum infusion rate of
0.7 mcg/kg/h (n=39)
G2: NS (n=42)
Surgery: cardiac surgery using cardiopulmonary bypass (n=81) and general surgery (n=17)
INT duration: within 1h of arrival on the ICU until the first 24h after that
Mean of age: G1=63.3, G2= 64.2, range= over 18
M/F: 54/27
MID 0.01-0.2 mg/kg/h and MO Outcomes: postoperative analgesia (MO)
Intervals: hourly up to first 24h postop period
Scales: VAS
Intubated patients receiving DEX required 80% less MID and 50% less MO
DEX could reduce the requirements for rescue sedation and analgesia in postop patients for up to 24h.
MO requirement was reduced by half in the DEX group.
DEX reported complications: bradycardia and hypotension

ABG=arterial blood gas; BP=blood pressure; BPI=brief pain inventory; C=control; CABG=coronary artery bypass graft; DEX=dexmedetomidine; G= group; HR=heart rate; ICU=intensive care unit; INT=Intervention; M/F=male/female number; MO=morphine; NR=not recorded; NRS=numeric rating scale; NS=normal saline; NV=nausea and vomiting; OAA=Observer's Assessment of Alertness/Sedation; OPCAB=off‑pump coronary artery bypass; PCEA=patient-controlled epidural analgesia; PCIA=patient-controlled intravenous analgesia; PNRS: pain number rating scale; Postop=postoperative; Preop=preoperative; RCT=randomized controlled trial; ROPI=ropivacaine; RSS=Ramsey sedation scale; TEC=thoracic epidural catheter; TRT=treatment; VAS=visual analogue scale; VRS=verbal rating score