RA UK Project Grant
Prospective evaluation of plasma levobupivacaine concentrations after fascia iliaca block in fractured neck of femur patients - a pilot study
Dr Peter Odor
Summary
A study to measure blood levels of a local anaesthetic following administration of a routine pain relief procedure to elderly patients with hip fracture.
Aim
This study aims to measure how the concentration of a local anaesthetic drug in the blood changes after the drug is administered for a pain-relieving nerve block procedure in elderly patients. The study will involve testing the local anaesthetic drug "levobupivacaine", used for a nerve block procedure called the "fascia iliaca block" (FIB), in elderly patients with hip fracture.
Background
FIB are popular nerve blocks and serious problems following the block are rarely recorded. However, unlike nerve blocks performed in younger healthier patients FIB are frequently given to elderly, frail patients. Symptoms of mild local anaesthetic toxicity (e.g. tingling around the mouth) are difficult to recognise in hip fracture patients, since many of hip fracture patients have disturbances of behaviour (such as dementia and delirium) that limit their ability to communicate early toxicity symptoms. Furthermore, clinical monitoring in hospitals after the nerve block is variable, meaning detection of problems can be challenging. Study into how the blood concentration of local anaesthetic drugs changes over time are related to patient age and the site of injection. Therefore it can be difficult to translate evidence from tests performed in young healthy patients to elderly patients. No study has yet examined blood levels of local anaesthetic in hip fracture patients with FIB.
This study is a pilot - to determine the scope of the problem and how further research should proceed. The justification for the study is to perform a preliminary investigation, in order to substantiate clinical data on the safety of FIB. The increasingly popularity of the FIB mandates an extra level of scrutiny for understanding and safety. Ultimately the results will be helpful in designing safer and more effective FIB for elderly patients in the future.
Methods
The only interventional procedure for the 10 patients to be recruited into the research project is a short series of blood tests. At the host intuition all patients currently receive a FIB, performed under optimal conditions by an anaesthetist, as part of a standard protocol of care. After hip fracture patients receive their FIB then the research team will take 7 bloods samples over 4 hours. Ideally these samples will be taken through a single cannula (plastic tube in the vein) in order to minimise discomfort for the patient.
The bloods samples will be analysed to measure levels of local anaesthetic used in the FIB. These results will be used to plot graphs of how the concentration of local anaesthetic changes over time and how far below the maximal level is to a level thought to result in toxicity.
Implications
The study will aid scientific understanding on change in local anaesthetic drug concentrations in the blood after nerve blocks, and planned follow on studies will use the data to produce safer and more effective nerve blocks for hip fracture pain relief.
