Ketamine With Multilevel Paravertebral Block for Post Video-assisted Thoracic Surgery Pain

Low Dose Intraoperative Intravenous Ketamine in Combination With Multilevel Paravertebral Block for Post Video-assisted Thoracic Surgery Pain: a Randomized Study

Postoperative pain after thoracic surgery is associated with adverse outcomes. The current strategy to prevent postoperative pain is the use of regional anesthesia and analgesic agents. In video-assisted thoracic surgery (VATS), thoracic paravertebral block has become the standard analgesic regimen which results in decreased postoperative pain and opioid consumption. The investigator would like to study the analgesic efficacy of low dose intravenous ketamine infusion during surgery in combination with thoracic paravertebral block on postoperative pain after VATS in a randomized study.

Inadequate pain control after thoracic surgery is associated with adverse events such as postoperative pulmonary complications (PPC), and chronic post surgical pain. Although the less invasive video-assisted thoracic surgery (VATS) has been used extensively as it produces optimal surgical outcomes and possible less postoperative pain, there are reports of inadequate pain control. Thoracic paravertebral block (TPVB) has been introduced as an effective method in postoperative pain management after VATS. It is associated with improved pain control and the reduction of opioid analgesic consumption in several studies. The use of intravenous low dose ketamine infusion during and after surgery has been shown to produce superior postoperative pain control in upper abdominal surgery and thoracotomy. The aim of the present study is to study the efficacy of intravenous low dose ketamine infusion during surgery on acute and chronic pain after VATS.

Participant allocated to this arm will receive intravenous ketamine infusion starting after the induction of anesthesia until the end of the surgery at the beginning of skin closure Participant will receive an ultrasound-guide thoracic paravertebral block using 0.5% plain bupivacaine prior to the induction of anesthesia

Participant allocated to this arm will receive intravenous normal saline solution infusion starting after the induction of anesthesia until the end of the surgery at the beginning of skin closure Participant will receive an ultrasound-guide thoracic paravertebral block using 0.5% plain bupivacaine prior to the induction of anesthesia

Amount of morphine (in milligrams) which is dispensed from a patient-controlled analgesia device (PCA)

Time period (in minutes) after the end of surgery until the time of first morphine solution is dispensed from PCA device

The value of peak flow velocity obtained from the first postoperative day will be compare with the value at the preoperative period

The value of peak flow velocity obtained from the first postoperative day will be compare with the value at the preoperative period

The score of the Thai version of PainDetect questionnaire will be obtained at 1 month postoperatively

The score of the Thai version of PainDetect questionnaire will be obtained at 3 months postoperatively

Inclusion Criteria: American Society of Anesthesiologist physical status 1-3 Scheduled for elective video-assisted thoracic surgery Able to operate a patient-controlled analgesia device (PCA) Exclusion Criteria: History of morphine allergy History of bupivacaine allergy Contraindication for ketamine infusion Contraindication for thoracic paravertebral block Anticipated postoperative positive pressure ventilation Body mass index more than 35 Any known psychiatric disorder

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