Intertransverse Process Block to Improve Quality of Recovery and Pain Management in Adult Cardiac Surgical Patients: a Prospective Double-Blinded Randomized Controlled Trial

Introduction:

The cornerstone of modern pain management in cardiac surgery lies in proactively preventing the development of chronic postsurgical pain (CPSP). This paradigm shift emphasizes pre-emptive interventions to disrupt the cascade of events and central sensitization that transform acute postoperative pain into a persistent, debilitating condition. CPSP, a significant and often underestimated consequence of cardiac surgery, affects a substantial proportion of patients, with prevalence rates ranging from 28% to 56% in the years following surgery. Its impact extends beyond mere discomfort, significantly impairing daily function, reducing quality of life, and imposing a substantial economic burden on the healthcare system.

The pathophysiology of CPSP involves a complex interplay of factors, with central sensitization playing a pivotal role. This process, characterized by heightened neuronal excitability within the central nervous system, amplifies pain signals and can lead to persistent pain even after the initial injury has healed. Therefore, a crucial aspect of CPSP prevention lies in disrupting the afferent nociceptive signals transmitted from the injured tissues to the spinal cord and brain, thereby preventing the establishment and perpetuation of central sensitization.

While opioids have traditionally been the mainstay of postoperative pain management, their use is not without significant drawbacks. Opioids can have dose-dependent side effects, including respiratory depression, nausea, and constipation. Furthermore, prolonged opioid use can lead to tolerance, opioid-induced hyperalgesia, and an increased risk of chronic opioid use. Recognizing these limitations, the current emphasis in pain management is on multimodal analgesia strategies that incorporate non-opioid medications and regional anaesthesia techniques to optimize pain control while minimizing the risks associated with opioid use.

Non-steroidal anti-inflammatory drugs (NSAIDs) offer a valuable adjunct in pain management, but their use in cardiac surgery is often limited due to concerns regarding bleeding complications and potential renal impairment. Other non-opioid analgesics, such as paracetamol and gabapentinoids, have shown limited efficacy in managing the intense pain associated with sternotomy. Regional anaesthesia techniques have emerged as promising strategies for both acute pain management and potential CPSP prevention in various surgical settings. Techniques such as epidural anaesthesia and paravertebral blocks have demonstrated efficacy in reducing postoperative pain intensity and opioid requirements. However, their application in cardiac surgery presents unique challenges. Epidural anaesthesia carries the risk of neuraxial hematoma due to systemic anticoagulation and heparinization, while paravertebral blocks may be associated with complications such as pneumothorax and pleural puncture. Erector spinae plane block (ESPB) has shown inconsistent results in reducing postoperative pain and morphine consumption in cardiac surgery. Parasternal plane blocks offer advantages over neuraxial techniques but may not adequately address visceral pain.