The Effect of Phrenic Nerve Block on Postoperative Shoulder Pain in Patients for Liver Resection.

The Effect of Phrenic Nerve Block on Postoperative Shoulder Pain in Patients for Liver Resection - a Double Blinded Randomised Controlled Trial.

The aim of this study is to explore whether the use of ultrasound guided phrenic nerve block can reduce the postoperative pain in the shoulder after liver resection. The intervention is directed postoperative to the patients experiencing novel right sided shoulder pain.

Background:

Patients undergoing both laparoscopic and open hepatic surgery often experience shoulder pain in the postoperative period, mostly on the right side.

The mechanism behind referral of pain from surgical sites to the ipsilateral (same side) shoulder is not fully understood. It has been stated, that the sharing of cervical sensory roots, leads the brain to an interpretation that the pain as originating from the ipsilateral shoulder, when the phrenic nerve is stimulated.

The phrenic nerve provides both sensory and motor nerves to the diaphragm, and sensory fibers to parts of the pleura and peritoneum. Furthermore, one anatomical study indicate, that the phrenic nerve on the right side supply the liver capsule with thin sensory nerves. This could also, in part, explain the shoulder pain after liver surgery.

Studies assessing the effect of phrenic block on shoulder pain by surgically applied intrathoracic block of the phrenic nerve, have found a pain reduction, without significant side effects. There are no available studies on the effect of phrenic nerve block after hepatic surgery. Blocking the nerve intraoperatively, as described in thoracic surgery, is not possible during these operations.

Pilot study of the incidence: A recent survey at Rigshospitalet, Denmark, revealed, that 19 out of 60 patients undergoing various types of hepatic surgery, experienced moderate to severe right sided shoulder pain in the post operative care unit. The only semi-effective treatment, has been opioids (morphine), often leading to significant side effects (nausea, vomiting , dizziness) with a potential for an increase in postoperative morbidity. Furthermore, referred shoulder pain affects the respiratory capacity postoperatively.

The investigators have developed a method for applying ultrasound-guided block at the lateral side of the neck, directly at the phrenic nerve where it crosses over the scaleni anterior muscle. The block is done with low volume of local anesthetic (only 3 ml very close to the nerve) aiming to avoid affection of the brachial plexus.

The phrenic nerve block have been performed at right sided shoulder pain in the postoperative care unit with marked effect within a few minutes (small nerve with little perineural insulation).

Trial endpoints:

The idea of the study is to perform a precise, low volume, ultrasound guided nerve block in the patients who experience a severe right sided shoulder pain (NRS >5 on a 0-10 scale) after liver surgery and evaluate the effect of active substance vs. placebo

Furthermore the investigators wish to stablish an evaluation of the duration of the phrenic nerve block when it comes to pain intensity, incidence of referred shoulder pain after liver surgery, and need for opioid and to evaluate the effect of the block on the lung function.

The study results will be described in a primary publication regarding the primary outcome, and a secondary publication regarding the incidence of acute respiratory and ventilatory affection observed in the PACU in patients undergoing open liver resection.

Inclusion Criteria:

• Age above 18.
• Patients scheduled for liver resection.
• Ability to give informed consent.

Exclusion Criteria:

• Participation in another clinical trial, dealing with pain or management of pain, which could affect this trial, evaluated by the investigator.
• Inability to talk and understand danish
• Drug or alcohol abuse
• Pregnancy
• Congestive heart failure (NYHA class III-IV), or other serious heart disease.
• Chronic obstructive lung disease, moderate or severe degree, or other significant lung disease
• Chronic or acute shoulder pain prior to surgery.
• Body Mass Index above 35.
• Infection at the site of the injection
• Allergy to ropivacaine

Postoperative:

• Shoulder pain score < 6 assessed on the numeric rating scale (0-10), 15 minutes after arrival in postanaesthetic care unit (PA CU).
• Insufficient epidural analgesia, or lack of epidural analgesia.
• Inability to visualize nervus phrenicus with sonography.
• Cerebral confusion, postoperative delirium or other medical condition hindering study intervention.
• Presence of an investigator with intervention competence is not available.