Since its first description in 1946, cPNB has evolved from a case report of a needle inserted through a cork taped to a patient's chest to a wide-spread and validated analgesic technique in the postoperative setting [1
]. The earliest reports of cPNB focused on prolonging intraoperative surgical anesthesia and the treatment of intractable hiccups [1
]. The indication for cPNB has evolved since then, and many indications have been described in the literature: treatment of vasospasm induced by Raynaud disease [4
]; induction of sympathectomy and vasodilation for improvement of blood flow after vascular surgery/trauma [5
], replantation or limb salvage [7
]; treatment of peripheral embolism [9
]; analgesia in the setting of trauma [11
]; treatment of chronic pain syndrome such as trigeminal neuralgia [12
], complex regional pain syndrome [13
], terminal cancer pain, [14
], and phantom limb pain [15
]. Independently of these indications, the majority of publications dealing with cPNB focus on postsurgical pain treatment, where evidence supports the concept that regional anesthesia and analgesia offers superior pain relief to systemic opioid analgesia following major surgery [17
]. However, postsurgical pain is the only indication which has been validated using randomized controlled trials (RCTs) [18
]. Compared with opioid analgesics cPNBs provide superior analgesia with a lower incidence of opioid-induced side effects like nausea, vomiting, pruritus, and sedation [21
]. Moreover, in a meta-analysis Rodgers et al. suggested that mortality associated with major surgery was reduced by 30% when central regional anesthesia was used combined or not with general anesthesia [23
]. On the other hand, a Cochrane review showed no impact of regional anesthesia compared to general anesthesia on mortality after hip fracture. Only the acute postoperative confusion was reduced after regional anesthesia [24
]. However, for continuous peripheral regional anesthesia these findings cannot be extrapolated. Though, continuous peripheral regional anesthesia offers improved functional outcomes after extremity surgery at least for a short term period (up to 6 months) [25
Despite this evidence of value, the hypothesis that regional anesthesia has an overall beneficial and long-lasting effect on patient outcome following surgery still remains difficult to prove and has been challenged, especially in times with reduced resources. For more than 30 years, regional anesthesia has challenged anesthesiologists to determine whether it offers real benefits over other types of anesthesia, such as preserving cognitive function after major surgery compared to general anesthesia, improving long-term joint function and rehabilitation leading to earlier return to work, reducing costs, reducing the need for blood transfusions and increasing patient-reported outcomes such as satisfaction, quality of life, and quality of recovery.
The implications of regional anesthesia after major surgery are multifaceted and not fully elucidated, thus requiring future studies with a focus on evaluating issues like implicating roles of mismanaged pain, environmental factors, stress responses associated with the perioperative period, long-term followups focusing on joint mobilisation and quality of life.
This paper will elucidate the benefits of cPNB over intravenous analgesia and single-shot perineural blocks (sPNB) according to the published literature and show some aspects for possible future directions.