Carl Moores

Thromboelastometry and Platelet Function during Acclimatization to High Altitude

Interaction between hypoxia and coagulation is important given the increased risk of thrombotic diseases in chronically hypoxic patients who reside at sea level and in residents at high altitude. Hypoxia alters the proteome of platelets favouring a prothrombotic phenotype, but studies of activation and consumption of specific coagulation factors in hypoxic humans have yielded conflicting results. We tested blood from 63 healthy lowland volunteers acclimatizing to high altitude (5,200 m) using thromboelastometry and assays of platelet function to examine the effects of hypoxia on haemostasis. Using data from two separate cohorts of patients following identical ascent profiles, we detected a significant delay in clot formation, but increased clot strength by day 7 at 5,200 m. The latter finding may be accounted for by the significant rise in platelet count and fibrinogen concentration that occurred during acclimatization. Platelet function assays revealed evidence of platelet hyper-reactivity, with shortened PFA-100 closure times and increased platelet aggregation in response to adenosine diphosphate. Post-expedition results were consistent with the normalization of coagulation following descent to sea level. These robust findings indicate that hypoxia increases platelet reactivity and, with the exception of the paradoxical delay in thromboelastometry clotting time, suggest a prothrombotic phenotype at altitude. Further work to elucidate the mechanism of platelet activation in hypoxia will be important and could impact upon the management of patients with acute or chronic hypoxic respiratory diseases who are at risk of thrombotic events.

Erratum to: Thromboelastometry and platelet function during acclimatisation to high altitude

Correction to: Thromboelastometry and Platelet Function during Acclimatization to High Altitude Thromb Haemost 2018; 118(01): 063-071 DOI: 10.1160/TH17-02-0138 In the Original Article by Rocke et al. “Thromboelastometry and platelet function during acclimatization to high altitude” (Thromb Haemost 2018; 118: 063-071) after publication of the article it has come to the corresponding authors attention that an author was inadvertently omitted from the manuscript. The author, Martin MacInnis, made a significant contribution to: 1. initiating the coagulation research that led to the manuscript, 2. designing the research protocol and performing the initial data analysis, 3. recruiting volunteers, writing applications for ethical approval and making other logistical arrangements that were necessary to complete the study. Martin MacInnis has read and approved the published version of the manuscript. Furthermore, a middle initial was added to the updated list (Shona E. Main) and misspelling of Elizabeth Horns surname was corrected. The amended author list is as above.

Long-term renal outcomes of consecutive patients undergoing open type IV thoracoabdominal aneurysm repair.

OBJECTIVE To evaluate long-term renal outcomes after open type IV thoracoabdominal aneurysm (TAAA) repair. DESIGN Retrospective analysis of a prospectively collected database of consecutive operated non-ruptured type IV TAAAs (2007-2011). METHODS Renal function was analysed by serum creatinine concentration, estimated glomerular filtration rate (eGFR) and Kidney Disease Outcomes Quality Initiative (KDOQI) stage. The primary outcome was the change in creatinine concentration from before surgery to defined time points after surgery: peak postoperative; discharge; at follow-up (>1 year postoperatively). Secondary outcomes were change in eGFR, change in KDOQI stage, dialysis requirement, and 30-day mortality. RESULTS Between 2007 and 2011, 53 open type IV TAAA repairs were performed. Median creatinine levels significantly increased in the immediate postoperative period, but returned to baseline by discharge. Thirteen patients (28.2%) had an improvement in follow-up eGFR of at least 20% compared with pre-operative eGFR or improved by one KDOQI stage. Twelve patients (26.1%) had a decline in eGFR of at least 20% or one KDOQI stage at follow-up. Three patients (7.5%) required temporary dialysis and one patient (1.9%) required permanent dialysis. The 30-day mortality was 1.9%. CONCLUSIONS This study demonstrates acceptable renal outcomes following open type IV TAAA repair. Open type IV repair remains the standard against which newer techniques should be compared.