PECS Block: Plasma Bupivacaine Level

Study Overview
=================
Brief Summary
-----------------
The purpose of this study is to determine peak plasma bupivacaine concentrations in a similar fashion for PECS I/II blocks. The investigators hypothesis is that the mean peak plasma levels for patients undergoing PECS I/II blocks will be less than the levels reported to cause early neurotoxicity of [2.2 (0.9) micrograms/ml]6 in patients receiving intravenous bupivacaine infusions.

Detailed Description
-----------------
Regional anesthesia techniques are common modalities used to provide analgesia following both upper and lower extremity surgeries. It is also often used for truncal procedures for the same purpose. A relatively new truncal block, first described in 2012 by Blanco, called the pectoralis nerve block (PECS I and II block) has been used successfully for breast surgery1-3. Despite its description and success in clinical practice, the extent of systemic absorption from this truncal plane block has not been described to date. However, in a study published in the British Journal of Anesthesia, this has been done for another truncal plane block, the transverse abdominus plane (TAP) block where the local anesthetic was noted to peak and had a mean total concentration of ropivacaine occurring at 30 minutes after the block4. During this study, samples were taken at 10, 20, 30, 45, 60, 90, 120, 180, and 240 minutes. The investigators anticipate that since this is a similar truncal plane block, absorption will be comparable in terms of timing. However, the concentration of drug absorbed may be different given the proximity to the ribs, intercostal and thoracic vasculature, and a higher concentration of local given the smaller plane for local anesthetic spread. Given that the investigators want to find the peak of the curve and the peak concentration of bupivacaine from the PECS block, the investigators feel will need 5 samples at the times outlined below. This number of samples was chosen to approximate a study published in 2004 where ten subjects received ropivacaine for scalp blocks and serum ropivacaine levels were measured at 15, 30, 45, 60, 90, and 120 minutes5. The investigators feel that the 120 minute measurement is well beyond the peak plasma level of bupivacaine given the findings in the TAP and scalp studies. Therefore,the investigators will collect the following samples at these times after the block is completed: 5, 10, 20, 40, 60, and 90 minutes. The purpose of this study is to determine peak plasma bupivacaine concentrations in a similar fashion for PECS I/II blocks. The investigators hypothesis is that the mean peak plasma levels for our patients undergoing PECS I/II blocks will be less than the levels reported to cause early neurotoxicity of [2.2 (0.9) micrograms/ml]6 in patients receiving intravenous bupivacaine infusions.

Official Title
-----------------
Determining Plasma Bupivacaine Levels Following Pectoral Nerve Blocks: A Prospective Observational Study

Conditions
-----------------
Nerve Blocks

Intervention / Treatment
-----------------
* Procedure: Unilateral PECS I and II block
* Procedure: Bilateral PECS I and II block
* Drug: Bupivacaine


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Patients receiving a unilateral PECS I and II block for any surgery being provided by Wake Forest Baptist Medical Center Exclusion Criteria: Subjects with contraindications to regional anesthesia, such as a history of allergy to amide local anesthetics, presence of a progressive neurological deficit, a pre-existing coagulopathy, infection at site of injection. or the following conditions: patient receiving any other additional local anesthetic from another procedure infection over site of block patient refusal significant renal or liver dysfunction on laboratory analysis weight <60 kg pregnancy

Ages Eligible for Study
-----------------
Minimum Age: 18 Years
Maximum Age: 70 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Design Details

Primary Purpose: Other
Allocation: Non-Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: unilateral PECS block patients<br>unilateral PECS I and II block using bupivacaine | Procedure: Unilateral PECS I and II block<br>* A truncal block called the pectoralis nerve block (PECS I and II block). Unilateral. Using Bupivacaine<br>Drug: Bupivacaine<br>* Bupivacaine solution 0.25%. At the PECS I site each patient will receive 10 cc of local anesthetic solution, and at the PECS II site an additional 20 cc of local anesthetic solution will be placed.<br>|
| Active Comparator: bilateral PECS block patients<br>bilateral PECS I and II block using bupivacaine | Procedure: Bilateral PECS I and II block<br>* A truncal block called the pectoralis nerve block (PECS I and II block). Bilateral. Using Bupivacaine.<br>Drug: Bupivacaine<br>* Bupivacaine solution 0.25%. At the PECS I site each patient will receive 10 cc of local anesthetic solution, and at the PECS II site an additional 20 cc of local anesthetic solution will be placed.<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Peak plasma bupivacaine concentration | Will be determined by samples collected at these times after the block is completed: 5, 10, 20, 40, 60, and 90 minutes | 90 minutes after dose | 
| Bupivacaine mean concentration | Calculated from samples at these times after the block is completed: 5, 10, 20, 40, 60, and 90 minutes | 90 Minutes after dose | 
| Standard deviations of plasma bupivacaine concentrations | Will be calculated using samples at these times after the block is completed: 5, 10, 20, 40, 60, and 90 minutes | 90 minutes after dose | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Rates of block success | As assessed by pin prick at the mid-clavicular line overlying the pectoralis major in between the dermatomes of T2 to T4. | 30 minutes after block | 
| Rates of adequate ultrasound success of appropriate separation of the muscular layers for each block. | be rated clinically on a 3 point scale: 0 = very poor spread with possible block failure, 1 = initially poor spread, but layers separated appropriately with high chance for successful block, 2 = spread clearly seen to separate muscular layers and successful block anticipated. | At the end of the block placement, 0 minutes timepoint. | 
| Rates of symptoms of local anesthetic systemic toxicity | Presence of symptoms from the end of the block to 90 minutes after the block. | 90 minutes after block | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
PECS I and II, PECS blocks