Serratus Anterior Plane Block: Post-operative Analgesia in Video-assisted Thoracic Surgery (Serrathos)

Serratus Anterior Plane Block: Post-operative Analgesia Technique in Video-assisted Thoracic Surgery. Efficacy Pilot Study and Population Pharmacokinetic Analysis

The objective of the study is to compare the efficacy of the Serratus Anterior Plane block (SPB) realised in its deep plane, with a multi-holed catheter in place for twenty four hours, to a standard intravenous analgesia for small videoassisted thoracic surgery interventions. The objective is also to evaluate the resorption rate of local anesthetic at this level, and make a population pharmacokinetic analysis.

In this study, 20 patients will be randomly assigned to one of two groups: ten patients will have a Serratus anterior plane block (SPB), with a first ropivacaine 0,375% bolus (0,4ml/kg), followed by an infusion of ropivacaine 0,2% at a 10ml/hr rate, through a multi-holed catheter located under the serratus anterior muscle, for a duration of 24 hours. The other group will have a standard intravenous analgesia with a PCA morphine-dehydrobenzperidol pump. Anesthesia protocol will be standardized. Except the infusion of ropivacaine for the SPB, per operative anesthesia and post operative analgesia will be the same for every usual patients. The investigators will evaluate post operative pain based on the visual analog scale, 24 hours morphine consumption, sensitivity of concerned territory. The investigators will also evaluate post operative chronic pain by assessing pain two months post operatively, completing two questionnaires of neuropathic pain: DN4 and QDSA short form. Finally, ropivacaine blood concentrations will be dosed by multiple blood samples taken over 24 hours after realizing the SPB, in order to make a population pharmacokinetic analysis, and evaluate the degree of ropivacaine resorption at this level.

Regional Anesthesia, Thoracic Surgery, Post-operative Pain, Post-operative Chronic Pain, Pharmacokinetic Analysis, Serratus Anterior Plane Block

SPB realized under ultrasound guidance. Infiltration of local anesthetic (bolus then infusion through a multi-holed catheter) is realized under the serratus anterior muscle at a level situated around the 5th to 6th intercostal space on the anterior axillary lign, in order to anesthetize the cutaneous lateral branches of the intercostal nerves, with a first ropivacaine 0,375% bolus (0,4ml/kg), followed by an infusion of ropivacaine 0,2% at a 10ml/hr rate, through a multi-holed catheter, for a duration of 24 hours.

Each patient controls his analgesia with an IV bolus of 2mg of morphine every 10 minutes if needed, with a maximum of 20mg every 4 hours.

Inclusion Criteria: American Society of Anesthesiologists physic status 1, 2 and 3 who require surgical video-assisted thoracoscopy or video assisted thoracic surgery without mini-thoracotomy Lung pathologies: biopsies symphysis, pleurectomy emphysema bullae resection pleural pathologies: biopsies collections, intra pleural effusion mediastinal pathologies: adenopathy staging cysts sympathectomy T2-T5 vagotomy splanchnicectomy Exclusion Criteria: refusal allergy to local anesthetic - contra-indication to the use of ropivacaine pregnancy liver failure severe kidney disease (GFR < 15ml/min) chronic intake of opioids neurological or psychiatric disorders interfering with pain assessment severe and morbid obesity (BMI > 35)

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