Duchenne Muscular Dystrophy: Considerations for Surgery

Introduction Planning and proactive assessment and management of risk is key to safe surgery – full assessments of heart and lungs important Various events may require general anaesthesia – Those related to DMD (e.g. muscle biopsy, joint contracture surgery, spinal surgery, gastrotomy) – Unrelated to DMD (e.g. acute surgical events)

Introduction Condition-specific issues must be considered for planning of safe surgery Surgery should be done in a full-service hospital with experience of patients with DMD: doctors should be informed of all medications Consideration must given to “stress steroid” coverage during surgery, for people treated with steroids at home.

Anaesthetic Considerations Always risks with anaesthetics: special considerations for DMD include – Exclusive use of a total intravenous anaesthetic (risk of malignant hyperthermia-like reactions and rhabdomyolysis with inhalation anaesthetic agents such as halothane and isoflurane) – Absolute contraindication of depolarising muscle relaxants e.g. suxamethonium chloride (succinylcholine) due to risk of fatal reactions

Blood-loss Minimisation Minimising blood loss is important especially in major surgery such as spinal fusion – Necessary to use mildly hypotensive anaesthetics, crystalloid bone allograft, and cell-saver technology – Other interventions can be considered e.g. use of aminocaproic acid or tranexamic acide to diminish intraoperative bleeding – Postoperative anticoagulation with heparin and/or aspirin is inappropriate – Use of compression stockings or sequential compression for prevention of deep-vein thrombosis might be indicated

Cardiac Considerations An echocardiogram and electrocardiogram should be performed prior to general anaesthesia. They should also be performed before undergoing conscious sedation or regional anaesthesia if the last investigation was more than one year previously, or if there has been an abnormal echocardiogram in the preceding 7-12 months. For local anaesthesia, an echocardiogram should be performed if there had been an abnormal result obtained previously

Respiratory Considerations (1) Even if someone with DMD already has problems with the breathing muscles, certain measures can make surgery safer, though there will still be an increased risk. A pre-operative assessment of breathing function in a centre familiar with DMD is very important – Need for adequate respiratory support during induction of maintenance of, and recovery from procedural sedation or general anaesthesia. – In particular, minimise risk of post-procedure endotracheal extubation failure, postoperative atelectasis and pneumonia – Goals can be achieved by providing non-invasively assisted ventilation and assisted cough after surgery for patients with significant respiratory-muscle weakness, as indicated by sub- threshold preoperative pulmonary function tests

Respiratory Considerations (2) Pre-operative training in and postoperative use of non- invasive ventilation and assisted cough is necessary for patients with baseline peak cough flow below 270L/min or with baseline maximum expiratory pressure is below 50cm water (measurements for older teenage/adult patients). Pre-operative training in and postoperative use of non- invasive ventilation strongly recommended for patients with baseline FVC below 50% predicted, and necessary if FVC below 30% predicted. Incentive spirometry not indicated – Potential lack of efficacy in patients with respiratory muscle weakness – Availability of preferred alternatives e.g. mechanical insufflations-exsufflation

Respiratory Considerations (3) After careful consideration of risks and benefits, patients with significant respiratory- muscle weakness might be eligible for surgery, albeit with increased risk, if they are highly skilled pre-operatively in the use of non- invasive ventilation and assisted cough Physiotherapists should always be involved if someone with DMD is having surgery

References & Resources The Diagnosis and Management of Duchenne Muscular Dystrophy, Bushby K et al, Lancet Neurology (1) & Lancet Neurology (2) – Particularly references, p The Diagnosis and Management of Duchenne Muscular Dystrophy: A Guide for Families TREAT-NMD website: CARE-NMD website: