Radial Artery Assessment in Surgical Coronary Revascularisation

The goal of this observational study is to learn about how screening tests inform the radial artery (RA) suitability for harvesting and coronary bypass grafting in adults with ischaemic heart disease. The main question it aims to answer is:

• What factors influence the diagnostic accuracy of RA screening in patients undergoing surgical coronary revascularisation?

Participants will:

* Receive an assessment of their RA through routinely used techniques (Modified Allen Test +/- pulse-oximetry, Barbeau Test and Ultrasound examination)
* Answer a symptoms scale about their physical experience after surgery

A multi-centre cross-sectional study design to investigate the validity of radial artery (RA) assessment techniques in adults with ischaemic heart disease undergoing surgical coronary revascularisation with their RA being selected as an autologous graft conduit.

Patients taking part in the study will receive an assessment of the arterial forearm circulation from their non-dominant upper extremity through multiple observations.

Pre-operative observations. Before surgery (in the ward environment after the patient is being admitted or whilst patient in the anaesthetic room) the forearm blood circulation is measured through a Modified Allen Test (MAT) (+/- pulse-oximetry), Barbeau Test and Ultrasonography examination. Assessment will be performed by experienced Surgical Care Practitioners/Advanced Nurse Practitioners/Cardiac Specialist Registrars. These assessments will inform the decision to surgically expose the RA.

Intra-operative observations. Oxygen saturation readings are taken prior to harvest the RA. Once the RA is surgically harvested a series of measures are taken through a validated structured questionnaire: the Radial Artery Quality Evaluation Survey (RAQES).

Observations at 4-6 weeks post operation. Patients finger movements, cold tolerance sensitivity and tactile/touch perception is measured through an ordinal symptoms scale (Follow-up Radial Artery Harvesting Scale) at post-operative day 2-5 and at follow-up appointment (3-6 weeks after surgery). Bilateral comparison between hands and forearms will be undertaken. A Surgical Care Practitioner will perform this assessment post-operatively.

Consecutive sampling will be used for the recruitment of study participants. The minimum required number of participants to test and verify research hypotheses is sixty-nine patients (N=69). An adaptive trial design will be implemented: at quarterly assessment points the statistical power is assessed and the remaining sample size required is updated accordingly.

Sample size calculation was undertaken using G\*Power software (version 3.1) using Chi-squared Test and adopting optimal effect size (w=0.4) and power (0.8).

Descriptive and inferential statistics will be used to perform quantitative analyses. Descriptive statistics (mode, median) will be implemented to analyse RAQES answers and ordinal symptoms scale findings and cross-tabulation used to record relationship between variables. Data analysis will also include measurement of sensitivity, specificity, positive and negative predictive values to investigate the validity of the RA assessment techniques. Correlational analysis will be implemented and Receiver Operating Characteristic curve analysis will be used to compare the diagnostic accuracy of the MAT, pulse-oximetry guided MAT and Barbeau Test with the ultrasonography examination.

Eligibility Criteria:
Inclusion Criteria:

* Male and female adults patients undergoing elective or urgent coronary artery bypass graft (CABG) surgery and radial artery (RA) harvesting in two Cardiothoracic hospitals.

Exclusion Criteria:

* Paediatric patients and/or adult patients undergoing emergency CABG will not be considered within the participants of this cross-sectional study, as well as patients lacking capacity to consent and non-English speaking patients requiring use of interpreters. Patients not wishing to participate in the study will also not be recruited.