Preoperative Paravertebral Block in Cancer Surgery of the Lung

Overview

The investigators aim to determine whether ultrasound-guided preemptive paravertebral blockade (PVB) local anaesthetic (pre-PVB LA), administered in addition to the post-operative PVB (post-PVB) local anaesthetic (LA) infusion, reduces acute postoperative pain, opioid requirement, chronic pain, and improves surgical recovery, in thoracoscopic surgery for lung cancer.

In the UK, there has been an increase in lung cancer operations, especially in high risk and elderly patients, improving survival from 10.6% in 2008 to 15.1% in 2013. Lung cancer surgery is associated with severe acute pain, a high incidence of respiratory complications and chronic post-surgical pain. Severe acute postoperative pain is a strong predictor of CPSP. The improvement of perioperative outcomes in elderly patients, the benefits of regional anaesthesia and reduction of chronic pain are investigative priorities of the Anaesthesia and Perioperative Care Setting Partnership. Enhanced recovery strategies include video-assisted thoracoscopic surgery (VATS), a minimally invasive alternative to open thoracotomy, which may be associated with less postoperative pain. Regional anaesthesia, by thoracic epidural analgesia (TEA) or PVB, is superior to systemic opioids in reducing acute pain after thoracotomy surgery. Preemptive analgesia describes the aim of minimizing central spinal pain transmission by noxious stimuli arising from events at surgery, by administering an analgesic technique prior to surgical incision. Regional blockade affects central sensitization, allowing analgesia to outlast the pharmacological sensory blockade. Compared to TEA initiated after surgery, acute pain severity is reduced by preemptive TEA. There are conflicting reports on the benefit of preemptive analgesia in other types of surgery, but TEA and PVB may prevent CPSP in thoracotomy and breast surgery. Some small studies have shown that pre-PVB reduces acute postoperative pain. Paravertebral blockade is known to be as effective as TEA for acute postoperative analgesia following thoracic surgery, whilst having a lower incidence of pulmonary complications, hypotension and nausea. It is conventional practice in many centres for the surgical administration and placement of a catheter at the end of surgery for postoperative LA infusion (post-PVB) as the sole method of regional analgesia. Preoperative PVB is less common: anaesthetists may use a landmark technique, single or multiple injections and different volumes/strengths of LA. Ultrasound guidance for pre-PVB injection increases accuracy. In an audit using this technique with post-PVB compared to post-PVB only, the investigators demonstrated reduced pain numerical rating scale (NRS) scores in elective VATS patients, (mean NRS at 24h 2.5 vs 4.5), and a reduction in the proportion of patients who experienced moderate-to-severe pain of NRS≥ 3 from 83% to 50% at 24h. The investigators therefore aim to evaluate the contribution of ultrasound-guided pre-PVB, administered in addition to the post-PVB LA infusion, in reducing the severity of acute postoperative pain, perioperative opioid requirement, development of CPSP, and improving patient outcome in lung cancer patients undergoing VATS.