Blood Levels of Local Anaesthetic in Knee Arthroplasty

Overview

The primary goal is to evaluate ropivacaine blood concentrations during and after local anaesthetic (ropivacaine) infiltration – the Caledonian technique – for total knee replacement surgery. The investigators plan to measure these levels by testing blood samples taken over a timed period. This will allow us to confirm whether the current regimen of local anaesthetic use is within safe limits.

Full Title of Study: “Blood Levels of Local Anaesthetic in Knee Arthroplasty: A Pharmacological Study of Ropivacaine Blood Levels During the Caledonian Technique for Knee Arthroplasty”

Study Type

  • Study Type: Observational
  • Study Design
    • Time Perspective: Prospective
  • Study Primary Completion Date: January 2013

Detailed Description

Local anaesthetic (LA) toxicity may occur when the blood levels of a drug become particularly high. There is a need to confirm that the technique is safe to use. In addition, journal case reports may only describe serious side-effects of toxicity such as abnormal heart rhythms whilst more subtle clinical signs are rarely reported. The investigators would like to study whether or not toxic levels may be approached in some patients or whether more subtle toxicity symptoms and signs are missed. For example, irregular heartbeat, low blood pressure or confusion/agitation. Therefore, the investigators intend to study ropivacaine blood levels in patients receiving a total knee replacement in the Golden Jubilee National Hospital. A series of timed samples will be taken during the perioperative period. The anaesthesia and surgery will be performed as routine and no new treatment will be involved. Patient demographics, ropivacaine blood levels and clinical observations following LA administration will be collected.

Interventions

  • Drug: Ropivacaine

Arms, Groups and Cohorts

  • Ropivacaine
    • Injection of local anaesthetic (ropivacaine) into the knee joint following knee arthroplasty. Total dose 200mls of 0.2% ropivacaine or 400mg at the time of surgery plus up to 5 top-up boluses (40mls of 0.2% ropivacaine or 80mg) postoperatively.

Clinical Trial Outcome Measures

Primary Measures

  • Plasma levels of ropivacaine
    • Time Frame: First 24 hours after surgery
    • Plasma levels of ropivacaine were analysed to determine total and free levels

Secondary Measures

  • Clinical observations
    • Time Frame: First 24 hours after surgery
    • Clinical observations, including potential symptoms and signs of local anaesthetic toxicity, were recorded at the same time as blood sampling
  • Evidence of dysrrhythmias as measured by 24-hour Holter monitoring
    • Time Frame: First 24 hours after surgery
    • 24-hour Holter monitoring was conducted to detect any potential sequelae of local anaesthetic toxicity

Participating in This Clinical Trial

Inclusion Criteria

  • Male or female patients greater than 65 years of age Exclusion Criteria:

  • Patients with a known sensitivity/allergy to ropivacaine or amide-type local anaesthetics – Patients who are not suitable for the Caledonian technique – Patients who refuse or are unable to give consent – Patients undergoing bilateral hip replacements – Patients with known heart, liver or kidney failure

Gender Eligibility: All

Minimum Age: 65 Years

Maximum Age: N/A

Are Healthy Volunteers Accepted: Accepts Healthy Volunteers

Investigator Details

  • Lead Sponsor
    • Golden Jubilee National Hospital
  • Collaborator
    • B. Braun Medical Inc.
  • Provider of Information About this Clinical Study
    • Sponsor
  • Overall Official(s)
    • Michael Gill, MBChB, Principal Investigator, NHS Research Scotland

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