Kar Prachi, Durga Padmaja, Gopinath Ramachandran
Department of Anesthesia and Intensive Care, Nizam's Institute of Medical Sciences, Hyderabad, Telangana, India.
J Anaesthesiol Clin Pharmacol. 2016 Oct-Dec;32(4):458-464. doi: 10.4103/0970-9185.194771.
Role of epidural dexmedetomidine in providing analgesia is well documented, but its effect on oxygenation and shunt fraction is not well established. We studied the hypothesis that epidural dexmedetomidine may improve oxygenation and shunt fraction during one-lung ventilation (OLV).
After taking Institutional Ethics Committee approval, sixty patients undergoing thoracotomy and OLV were randomized to receive epidural ropivacaine with saline (RS group) or epidural ropivacaine with dexmedetomidine (RD group). Group RS received 7 ml of ropivacaine 0.5% with 1.5 ml normal saline (NS) bolus while RD group received 7 ml of 0.5% ropivacaine with 1 mcg/kg dexmedetomidine reconstituted in 1.5 ml NS. This was followed by infusion of 5 ml/h of 0.5% ropivacaine in RS group and 5 ml/h of 0.5% ropivacaine containing 0.2 mcg/kg of dexmedetomidine in RD group. Arterial and central venous blood gas parameters were obtained 15 minutes after intubation during two lung ventilation (TLV15), 15 and 45 min after OLV (OLV15, OLV45) and 15 minutes after reinstitution of two lung ventilation (ReTLV).
RD group had better oxygenation (254.2 ± 72.3 mmHg, 240.60 ± 59.26 mmHg) as compared to RS group (215.2 ± 64.3 mmHg, 190.7 ± 61.48 mmHg) at OLV15 ( - 0.04) and OLV45 ( - 0.004) respectively. Shunt fraction in RD group was (30.31 ± 7.89%, 33.76 ± 8.89%) and (35.14 ± 7.58%, 39.57 ± 13.03%) in RS group at OLV15 and OLV45, respectively. The increase in the shunt fraction from TLV15 was significantly greater in RS group than RD group both at OLV15 ( - 0.03) and OLV45 ( - 0.03). The sevoflurane and fentanyl requirement was lower in RD group.
Epidural dexmedetomidine improves oxygenation and reduces shunt fraction during OLV, in patients undergoing thoracotomy. It also reduces intraoperative anesthetic and analgesic requirement.
硬膜外注射右美托咪定的镇痛作用已有充分文献记载，但其对氧合及分流分数的影响尚不明确。我们研究了硬膜外注射右美托咪定可能改善单肺通气（OLV）期间氧合及分流分数的假说。
经机构伦理委员会批准后，60例行开胸手术及OLV的患者被随机分为接受含生理盐水的硬膜外罗哌卡因组（RS组）或含右美托咪定的硬膜外罗哌卡因组（RD组）。RS组接受7 ml 0.5%罗哌卡因加1.5 ml生理盐水推注，而RD组接受7 ml 0.5%罗哌卡因加1 μg/kg右美托咪定用1.5 ml生理盐水复溶。随后，RS组以5 ml/h的速度输注0.5%罗哌卡因，RD组以5 ml/h的速度输注含0.2 μg/kg右美托咪定的0.5%罗哌卡因。在双肺通气（TLV15）插管后15分钟、OLV后15分钟和45分钟（OLV15、OLV45）以及恢复双肺通气后15分钟（ReTLV）获取动脉和中心静脉血气参数。
在OLV15（-0.04）和OLV45（-0.004）时，RD组的氧合情况（分别为254.2±72.3 mmHg、240.60±59.26 mmHg）优于RS组（分别为215.2±64.3 mmHg、190.7±61.48 mmHg）。在OLV15和OLV45时，RD组的分流分数分别为（30.31±7.89%，33.76±8.89%），RS组分别为（35.14±7.58%，39.57±13.03%）。在OLV15（-0.03）和OLV45（-0.03）时，RS组分流分数从TLV15开始的增加均显著大于RD组。RD组七氟醚和芬太尼的需求量较低。
对于行开胸手术的患者，硬膜外注射右美托咪定可改善OLV期间的氧合并降低分流分数。它还可降低术中麻醉和镇痛需求。
