O030 Image-analysis algorithm to determine quality of cold perfusion in kidney transplantation

Introduction

Surgeon assessment of visual ‘quality of perfusion’ (QOP) influences kidney discard and predicts transplant outcome. However, this assessment is subjective and bias-prone.

We aimed to design an application utilising a smartphone camera to make this assessment objective and enhance decision making.

Methods

The QOP in photographs of backbench kidneys was graded from 1 (ideal) to 5 (very poor) by three independent surgeons. A training cohort was used to develop an image-analysis algorithm, which was validated in a separate cohort.

Results

Analysing surgeon scores of 174 kidney images revealed that inter-rater agreement was good for kidneys displaying the best (rated 1) and worst (rated 4 or 5) QOP. However, for intermediate scores inter-rater agreement was poor. Inter-rater agreement between surgeons decreased as they graded more images; as surgeons fatigued, their ability to classify images worsened. A training cohort (n=174 kidneys) was used for algorithm development. First, small regions within each image were mapped within the CEILAB colour-space, where well-perfused and poorly perfused areas show clear separation. To generate a score for each kidney these regions are compared with ideally flushed kidney tissue. Testing our algorithm (validation cohort - n=29 kidneys) revealed strong correlation between image-analysis QOP score and surgeon assessment, r=0.789 (0.587–0.899), P<0.001.

Conclusion

Surgeon inter-rater agreement on kidney QOP is low for kidneys with borderline QOP and worsens with fatigue. We provide a QOP score utilising an image-analysis algorithm, which correlates with surgeon scoring. With additional images and training this could provide an objective, numerical, point-of-care assessment of organ quality.

Take-home message

Current visual assessment of transplant organ quality is subjective and bias-prone. This body of work attempts to create a point-of-care image-analysis application to provide an objective numeric organ quality score.

O59: USE OF DEXTRAN 40 FOLLOWING PANCREAS TRANSPLANT MAY REDUCE EARLY INFLAMMATION AND SIGNIFICANT BLEEDING COMPARED TO A HEPARIN-BASED PROTOCOL

Introduction

Dextran 40 (D40) is a synthetic colloid with anticoagulant properties, which is commonly used instead of heparin following pancreas transplantation, however there is a lack of evidence over which is more effective. Graft thrombosis and pancreatitis, which may be mediated through micro or macrothrombosis within the graft, remain significant complications following pancreas transplantation. We hypothesised that D40 reduces inflammation through its antithrombotic pro-microcirculatory effects. We aimed to evaluate D40 compared to a heparin-based protocol by comparing post-operative complications and post-transplant levels of inflammation.

Method

Data were collected retrospectively for pancreas transplant patients between December 2009 and August 2018 – 26 patients had been treated with the pre-Dextran protocol and 37 had received D40. Post-operative complications and inflammatory markers (WCC, CRP and amylase) on post-operative days 1, 2, 3 and 7 were compared between the two groups. Potential confounders were also recorded.

Result

Patients in the D40 group had similar thrombosis rates but were less likely to have had substantial post-operative bleeding compared to the heparin-based protocol. The group who received D40 had significantly lower CRP and WCC on days 2, 3 and 7. The differences on days 3 and 7 remained when the results were adjusted for the significant confounders - cold ischaemic time and donor age.

Conclusion

D40 appears to be as effective as IV heparin at preventing graft thrombosis following pancreas transplant, and to confer a reduced risk of bleeding. It may also reduce post-operative inflammatory processes, leading to reduced graft pancreatitis.

Take-home message

Using Dextran 40 as an anticoagulant after pancreas transplantation is as effective as IV heparin at preventing graft thromboses and has a reduced risk of bleeding.

O73: IMPROVING CONSENT WITH A VISUAL TOOL FOR COMMUNICATING SURGICAL RISKS

Introduction

Patients must understand the risks of a procedure to provide valid consent. Guidance from the General Medical Council and Royal College of Surgeons of England highlights that surgeons need to communicate risks in a way that patients can understand, and both institutions specifically mention the use of written information. We aimed to improve communication of surgical risks to patients undergoing thyroid surgery.

Method

Over 3 months, all patients undergoing thyroid surgery in a tertiary referral centre were included (n=51). Participants were given a 10 point questionnaire after the consent process. Each question had 4 options (very common, common, uncommon and rare) and tested participant understanding of surgical risks. Our intervention was a single page annotated graphic, which used a traffic-light system to explain surgical risks.

Result

When consented prior to our intervention (n=28), patient understanding of the magnitude of surgical risks was poor; median questionnaire score was 4.5 out of 10, and for some questions <15% of participants selected the correct answer. Following introduction of our surgical risk tool (n=23) median overall participant score increased from 4.5 (range 2-7) to 8.0 (4-10) out of 10 (P<0.0001; Mann-Whitney U test).

Conclusion

Patients must understand the risks of an operation, and the magnitude of those risks, in order to provide valid consent. Addition of a visual surgical risk tool enabled us to increase patient understanding of surgical risks, improving the consent process. This has implications not just for thyroid surgery, but for any procedure requiring consent.

Take-home message

Clear communication of surgical risks is essential to obtain valid consent. The use of a visual surgical risk tool increases patient understanding of risks, and therefore improves the consent process.

O6: EARLY ANASTOMOTIC BILIARY COMPLICATIONS AFTER LIVER TRANSPLANTATION

Introduction

Biliary leaks and anastomotic strictures are common early biliary complications (EBC) following liver transplantation. However, their impact on outcomes remains controversial and poorly described.

Method

The NHS registry on adult liver transplantation between 2006 and 2017 was retrospectively reviewed (n=8304). Multiple imputations were performed to account for missing data. Adjusted regression models were used to assess predictors of EBC, and their impact on outcomes. 35 potential variables were included, and backwards stepwise selection enabled unbiased selection of variables for inclusion in final models.

Result

EBC occurred in 9.6% of patients. Adjusted cox regression revealed that EBCs have a significant and independent impact on graft survival (Leak HR=1.325; P=0.021, Stricture HR=1.514; P=0.002, Leak plus stricture HR=1.533; P=0.034) and patient survival (Leak HR=1.218; P=0.131, Stricture HR=1.578; P<0.001, Leak plus stricture HR=1.507; P=0.044). Patients with EBC had longer median hospital stay (23 versus 15 days; P<0.001) and increased chance for readmission within the first year (56% versus 32%; P<0.001). On adjusted logistic regression the following were identified as independent risk factors for development of EBC: donation following circulatory death (OR=1.280; P=0.009), accessory hepatic artery (OR=1.324; P=0.005), vascular anastomosis time in minutes (OR=1.005; P=0.032) and ethnicity ‘other’ (OR=1.838; P=0.011).

Conclusion

EBCs prolong hospital stay, increase readmission rates and are independent risk factors for diminished graft survival and increased mortality in liver transplantation. We have identified factors that increase the likelihood of EBC occurrence; further research into interventions to prevent EBCs in these at-risk groups is vital to improve liver transplantation outcomes.

Take-home message

Using a large registry database we have shown that early anastomotic biliary complications are independent risk factors for decreased graft survival and increased mortality after liver transplantation. Research into interventions to prevent biliary complications in high risk groups are essential to improve liver transplant outcomes.

Risk factors and impact of early anastomotic biliary complications after liver transplantation: UK registry analysis

Background

Biliary leaks and anastomotic strictures are common early anastomotic biliary complications (EABCs) following liver transplantation. However, there are no large multicentre studies investigating their clinical impact or risk factors. This study aimed to define the incidence, risk factors and impact of EABC.

Methods

The NHS registry on adult liver transplantation between 2006 and 2017 was reviewed retrospectively. Adjusted regression models were used to assess predictors of EABC, and their impact on outcomes.

Results

Analyses included 8304 liver transplant recipients. Patients with EABC (9·6 per cent) had prolonged hospitalization (23 versus 15 days; P < 0·001) and increased chance for readmission within the first year (56 versus 32 per cent; P < 0·001). Patients with EABC had decreased estimated 5-year graft survival of 75·1 versus 84·5 per cent in those without EABC, and decreased 5-year patient survival of 76·9 versus 83·3 per cent; both P < 0.001. Adjusted Cox regression revealed that EABCs have a significant and independent impact on graft survival (leak hazard ratio (HR) 1·344, P = 0·015; stricture HR 1·513, P = 0·002; leak plus stricture HR 1·526, P = 0·036) and patient survival (leak HR 1·215, P = 0·136, stricture HR 1·526, P = 0·001; leak plus stricture HR 1·509; P = 0·043). On adjusted logistic regression, risk factors for EABC included donation after circulatory death grafts, graft aberrant arterial anatomy, biliary anastomosis type, vascular anastomosis time and recipient model of end-stage liver disease.

Conclusion

EABCs prolong hospital stay, increase readmission rates and are independent risk factors for graft loss and increased mortality. This study has identified factors that increase the likelihood of EABC occurrence; research into interventions to prevent EABCs in these at-risk groups is vital to improve liver transplantation outcomes.

Performance and learning curve of a surgical care practitioner in completing hip aspirations

INTRODUCTION The roles of non-medically trained practitioners within the NHS are expanding; they are now being employed by many specialties, including surgery, to relieve pressures on healthcare teams. AIMS To investigate the learning curve and competence of an orthopaedic surgical care practitioner (SCP) in performing hip aspirations. METHODS Data were retrospectively collected on 510 orthopaedic hip aspirations, of which 360 were completed by a single SCP and 150 were completed by surgeons before the SCP took over routine aspiration. The 360 aspirations completed by an SCP were separated into groups of 30 by date, so any trend in failure rate could be analysed. Ordinal χ² analysis was used to analyse this trend and Pearson χ² analysis was used to analyse differences in failure rates between professionals. RESULTS The hip aspiration failure rate for the SCP was significantly lower than for the surgeons; 8.6% vs 20.7% (P<0.001). With the experience gained in completing the first 210 procedures, the failure rate of the SCP dropped to 3.3% for the remaining 150 procedures. This downward trend in hip aspiration failure rate, with advancing experience of the SCP, was shown to be statistically significant (P=0.006). DISCUSSION SCPs who complete hip aspirations on a regular basis have significantly lower failure rates than surgeons, probably as a result of the learning curve, which this study demonstrated. Other trusts should consider delegating routine hip aspiration work to a designated SCP to lower failure rates.