Comparison of the Local Anaesthetics Articaine and Bupivacaine in Treatment of Acute Sternum Pain After Heart Surgery

The purpose of this study is to examine the wound infusion of articaine for treatment of acute post-sternotomy pain in a placebo-controlled manner using a prospective and randomized design and an active control (bupivacaine)

Acute pain after open heart surgery can be moderate or strong and is mostly caused by sternotomy. Pain is the worst during the first two post-operative days and, if not adequately treated, can delay the patient´s recovery from surgery. Sternotomy pain can be alleviated by using paracetamol, non-steroidal anti-inflammatory drugs (NSAIDs) and opioids. All these drugs may have remarkable side-effects which may delay the recovery from surgery: opioids are respiratory depressants and slower the gastrointestinal motility, NSAIDs reduce intrarenal blood flow and may disturb coagulation. Post-operative opioid consumption can be reduced by using wound infiltration analgesia.

The use of wound infiltration analgesia has not been extensively investigated in treatment of acute pain after sternotomy. There is some evidence, that 0.5% bupivacaine reduces the acute post-sternotomy pain when infused constantly via catheters placed under the fascia (periosteal placement) and the skin.

During 48 hours infusion toxic bupivacaine plasma levels were not observed. There is an evidence that local anesthetics can be bacteriostatic both in vitro and in vivo.

Articaine is an amide-type local anesthetics, which has been used extensively in dental procedures since more than forty years. It has been successfully used in infiltration, epidural, spinal and other regional anesthesia procedures. Articaine is quickly hydrolyzed in plasma and excreted by kidneys. Clearance of articain (500-1110l/h) is faster than that of lidocaine (68l/h) and it is also the reason for articaine´s low toxicity profile. Because of it´s low toxicity and high ability to penetrate the periosteal tissue, articaine may be advantageous in treatment of acute pain after sternotomy, but aforementioned indication for use of articaine has not been investigated. Compared to other local anesthetics, articaine in high concentration has the same neurotoxicity profile, when injected directly into rat´s sciatic nerve. Articaine has not been extensively compared to other local anesthetics, but according the latest odontologic investigation, single dose 0.5% bupivacaine and single-dose 4% articaine were comparable in their analgesic effects during tooth extraction procedure. There are no controlled randomized trials comparing analgesic effect of articaine and other local anesthetics infusions.

In our investigation bupivacain 0.5 % was chosen as an active control, because it has appeared effective in acute postoperative pain and it has reduced the need for opioid analgetics after sternotomy

Eligibility Criteria:
Inclusion Criteria:

* elective procedure
* open heart surgery
* aortic valve surgery
* mitral valve surgery
* atrial septal defect repair surgery
* intracardial myxoma removal surgery

Exclusion Criteria:

* local anesthetic allergy
* sulphide allergy
* asthma
* pregnant women
* neurological disease (TIA excluded)
* congestive heart failure
* left ventricle ejection fracture under 0.3
* liver failure
* diabetes mellitus with documented polyneuropathy
* chronic pain condition
* mother tongue not finnish or swedish
* patients, who do not agree blood transfusions