PK/PD Levobupivacaine with and Without Epinephrine After Ultrasound Guided ESP Block

Video-assisted thoracic surgery (VATS) is one of the most common procedures performed in thoracic surgery, mainly because it has made it possible to solve many pathologies that previously required a thoracotomy with all the complications that that meant. VATS has been shown to be beneficial for patients, for many reasons such as lower mortality, better postoperative lung function, and shorter stay during hospitalization.

Less invasive procedures such as VATS, where the surgical incision is small and avoids costal resection, produces less postoperative pain when compared to a thoracotomy, this has been objectified by numerous studies that have found lower scores on the numerical verbal scale (NVE) and fewer requirements for pain relievers. Despite the fact that VATS produces less acute postoperative pain (VNS 4-5 on the first postoperative day in VATS vs VNS 6 in thoracotomies), the incidence of chronic postoperative pain ranges from 20 to 47%, which is comparable to thoracotomy, mainly due to damage to the intercostal nerves and inadequate analgesia.

It has been seen that one of the factors associated with the appearance of chronic pain after chest surgery is severe acute pain in the first three postoperative days. Acute pain in VATS is caused by surgical trauma to muscular and bone structures of the thorax, achieving good analgesia is important to maintain adequate respiratory function and avoid complications such as atelectasis, hypoxemia and possible pneumonia.

Currently, there is no standardized management or single technique to manage postoperative pain after VATS, there are many options available ranging from intravenous opioids, morphine or fentanyl Patient-controlled analgesia, peripheral nerve blocks, intercostals, paravertebral and epidural blocks. Each of them with advantages and disadvantages, but without being able to demonstrate a clear superiority between them, both the paravertebral and epidural blocks are the ones that accumulate the most reports in the literature regarding the management of postoperative pain, but at the same time they are not exempt from complications such as technical failure, hypotension and difficulty of the procedure. In addition to documenting a low use of thoracic epidurals in VATS.

At the end of 2016, the description of the Erector Spinal Block (ESP) by Forero was published, it blocks the ventral and dorsal branch of the unilateral thoracic roots. It corresponds to an interfacial block that produces an extensive multidermatomal sensitive block with a single puncture, covering the anterior, lateral and posterior aspect of the thorax. One of its main advantages would be safety, possible less nerve damage and pneumothorax, as well as the simplicity of execution of this block. What has positioned it as another analgesic alternative in this type of surgery.

In ESP, the pharmacokinetic (PK) profile that local anesthetics would have when injected into this interfacial compartment has not yet been described, and what will be the real impact of the use of vasoconstrictor in terms of plasma levels and duration of the block.

Considering the above, it is important to know the pharmacodynamics of levobupivacaine after performing an ESP block with ultrasonography in order to know the risks of toxicity from local anesthetics as well as to clinically characterize this block in patients who will undergo VATS.

The first objective of this study is to compare the plasma levels of levobupivacaine achieved after performing an ESP Block with or without epinephrine. As secondary objectives, it is proposed to characterize the block in terms of duration, pain, opioid requirements in the first 24 hours and adverse events, in both groups.

Inclusion criteria

• Indication of VATS
• ASA I-II
• Body mass index (BMI) 20-34 kg / m2

Exclusion criteria

• Patients with conversion to thoracotomy
• History of chronic pain
• Drug abuse
• Psychiatric illness
• Allergic to some of the drugs used in the study
• Chronic analgesic users
• History of peripheral neuropathy
• Who refuse the procedure