OP113: Low molecular weight heparin (LMWH) thromboprophylaxis in free tissue transfer patients for head and neck cancer

Abstract

UK data shows 25,000 preventable deaths from hospital acquired venous thromboembolism (VTE) annually. National Institute of Clinical Excellence (NICE) guidance mandates thromboprophylaxis in patients undergoing surgery. Local protocols provide guidelines for low and high-risk patients. Pathology and treatment in Head and Neck cancer (HNC) patients result in high-risk categorisation. In addition to mechanical VTE prophylaxis, pharmacological VTE prophylaxis uses low molecular weight heparin (LMWH). Major HNC surgery carries risk of post operative haemorrhage but there are no guidelines specific for these procedures. Our local guidelines changed, requiring an increased dose of LMWH. We report haemorrhagic complications in HNC surgical patients with varying LMWH dose and time of administration. HNC patients undergoing major surgery were identified from our database and documentation, drug charts and notes were scrutinized. Patients were classified by dose of LMWH prophylaxis received. Post-operative haemorrhagic complications and time of LMWH administration for each dose category were determined. Data from 67 patients were analysed. In total 31.3% were administered low dose LMWH (enoxaparin 20 mg) prophylaxis and 68.7% high dose (40 mg enoxaparin). The low dose group had 5% haemorrhagic complication rate and 17% in the high dose cohort. Ablative and reconstructive surgery was similar in each group. No patients taking antiplatelet therapy prior to surgery suffered haemorrhagic complications. Patients who suffered bleeding complications received LMWH prophylaxis the evening before or on the evening of surgery. No patients receiving prophylaxis on induction suffered haemorrhagic complications. No excess intra-operative bleeding was recorded. No patients developed clinically detectable deep vein thrombosis (DVT) or VTE. Our study shows increased post-operative bleeding in patients receiving 40 mg vs 20 mg enoxaparin. No patients developed DVT and no intra-operative haemostatic difficulty was recorded in any case. No bleeding complications were recorded where LMWH was given on induction.