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

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.

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

1. Lung pathologies:

   • biopsies
   • symphysis, pleurectomy
   • emphysema bullae resection

2. pleural pathologies:

   • biopsies
   • collections, intra pleural effusion

3. mediastinal pathologies:

   • adenopathy staging
   • cysts
   • sympathectomy T2-T5
   • vagotomy
   • splanchnicectomy

Exclusion Criteria:

1. refusal
2. allergy to local anesthetic - contra-indication to the use of ropivacaine
3. pregnancy
4. liver failure
5. severe kidney disease (GFR < 15ml/min)
6. chronic intake of opioids
7. neurological or psychiatric disorders interfering with pain assessment
8. severe and morbid obesity (BMI > 35)