Development of a geospatial approach for the quantitative analysis of trauma center access.

INTRODUCTION: Decisions around trauma center (TC) designation have become contentious in many areas. There is no consensus regarding the ideal number and location of TC and no accepted metrics to assess the effect of changes in system structure. We aimed to develop metrics of TC access, using publicly available data and analytic tools. We hypothesize that geospatial analysis can provide a reproducible approach to quantitatively asses potential changes in trauma system structure. METHODS: A region in New York State was chosen for evaluation. Geospatial data and analytic tools in ArcGIS Online were used. Transport time polygons were created around TC, and the population covered was estimated by summing the census tracts within these polygons. Transport time from each census tract to the nearest TC was calculated. The baseline model includes the single designated TC. Model 1 includes one additional TC, and Model 2 includes two additional TC, chosen to maximize coverage. The population covered, population-weighted distribution of transport times, and population covered by a specific TC were calculated for each model. RESULTS: The baseline model covered 1.12 × 10 people. The median transport time was 19.2 minutes. In Model 1, the population covered increased by 14.4%, while the population catchment, and thus the estimated trauma volume, of the existing TC decreased by 12%. Median transport time to the nearest TC increased to 20.4 minutes. Model 2 increased coverage by 18% above baseline, while the catchment, and thus the estimated trauma volume, of the existing TC decreased by 22%. Median transport time to the nearest TC decreased to 19.6 minutes. CONCLUSIONS: Geospatial analysis can provide objective measures of population access to trauma care. The analysis can be performed using different numbers and locations of TC, allowing direct comparison of changes in coverage and impact on existing centers. This type of data is essential for guiding difficult decisions regarding trauma system design. LEVEL OF EVIDENCE: Care management, level IV.

Changes in Markers of Thrombin Generation and Interleukin-6 During Unicondylar Knee and Total Knee Arthroplasty.

BACKGROUND: Total knee arthroplasty (TKA) is associated with a risk of thromboembolism requiring routine thromboprophylaxis, but there is debate about the risk with unicondylar knee arthroplasty (UKA) as it is a more minor procedure. We sought to investigate the relative risk of thromboembolism with UKA compared to TKA and one-staged bilateral TKA (BTKA) by measuring the increase in circulating biochemical markers of thrombin generation during the procedures. Degree of surgical trauma was also assessed by measuring interleukin-6, a marker of metabolic injury. METHODS: We prospectively studied a total of 75 patients: 25 patients undergoing UKA, unilateral TKA, and BTKA, respectively. All patients had surgery performed with tourniquet and received no tranexamic acid. Blood samples were taken during surgery and assayed for circulating markers of thrombin generation: prothrombin fragment 1+2 (F1+2) and thrombin-antithrombin complexes plus interleukin-6. RESULTS: Thrombin-antithrombin complexes, increased during all time points (P < .001) but was not significantly different between surgical treatment groups. F1+2 also rose significantly during surgery, with no significant difference between UKA and TKA. There was, however, a significant difference in F1+2 between BTKA and UKA or TKA (P < .02). Interleukin-6 rose minimally with UKA but rose significantly with TKA and BTKA (P < .001). CONCLUSION: Based on these data of circulating biochemical markers, patients undergoing UKA are at similar risk of thromboembolism with respect to TKA despite a lower index of metabolic injury. We believe that UKA patients should receive thromboprophylaxis comparable to TKA patients.

The incidence and risk factors for post-operative ileus after spinal fusion surgery: a multivariate analysis.

PURPOSE: Post-operative ileus is a recognized complication of surgery. Little is known about the incidence and risk factors for post-operative ileus following spinal fusion surgery. To report the incidence and to assess for independent risk factors of post-operative ileus after spinal fusion surgery. METHODS: Retrospective single-centre cohort study. Patients with prolonged or recurrent post-operative ileus were identified by review of hospital stay documentation. Patients with post-operative ileus were matched 1:2 to a control cohort without post-operative ileus. Uni and multi variate analyses were performed on demographic, comorbidity, surgical indication, medication, and peri-operative details to identify risk factors for post-operative ileus. RESULTS: Two thousand six hundred and twenty five patients underwent spinal fusion surgery between January 2012 and December 2012. Forty nine patients with post-operative ileus were identified (1.9 %). Post-operative length of hospital stay was significantly longer for patients with post-operative ileus (9.3 ± 5.2 days), than control patients (5.5 ± 3.2 days) (p < 0.001). Independent risk factors were Lactated Ringers solution (aOR: 2.12, p < 0.001), 0.9 % NaCl solution (aOR: 2.82, p < 0.001), and intra-operative hydromorphone (aOR: 2.31, p < 0.01) and a history of gastro-oesophageal reflux (aOR: 4.86, p = 0.03). Albumin administration (aOR: 0.09, p < 0.01) was protective against post-operative ileus. CONCLUSIONS: Post-operative ileus is multifactorial in origin, and this study identified intra-operative hydromorphone and post-operative crystalloid fluid administration ≥2 litres as independent risk factors for the development of ileus.