Dermatomyositis

Aspiration risk - Dysphagia from oropharyngeal and upper esophageal weakness, with reflux on top of it, is the rule in significant disease. Aspiration pneumonia in this population carries real mortality. Rapid-sequence induction, head up, and suction ready.

Lung versus pump - Pulmonary function tests show a restrictive pattern either way, but interstitial lung disease also drops the diffusing capacity while pure respiratory muscle weakness leaves it normal. That one number tells you whether you are managing a stiff lung or a weak bellows. Add high-resolution CT of the chest if the patient has respiratory symptoms or an abnormal chest radiograph, and look for the antisynthetase antibodies (anti-Jo-1 most often), which track with interstitial lung disease.

Subclinical cardiac involvement - The heart is usually quiet on exam, so order the ECG anyway. It picks up conduction abnormalities and arrhythmias, and myocarditis, congestive heart failure, and coronary disease are all described.

Occult cancer - Malignancy turns up in 24% of adults with dermatomyositis — ovary, lung, pancreas, stomach, colon, and non-Hodgkin lymphoma — with the risk highest in the first year and still elevated at five. Male sex, older age at onset, dysphagia, and the absence of interstitial lung disease all point toward an occult tumor. The juvenile form does not carry this association.

Calcinosis and the airway - Calcium deposits favor the neck, jaw, and face, and vocal cord calcification has been reported. In a published case the mouth opening would not admit a video laryngoscope and fiberoptic intubation with a soft flex-tip tube was required, with ENT on standby and a surgical airway available. Pull the previous anesthetic records before you plan.

Positioning and bone fragility - Long-term glucocorticoids give osteoporosis, and in advanced calcinosis the tendons and ligaments themselves can fracture without careful padding and support. Thrombosis is common in advanced disease, so keep venous access and prophylaxis in the plan.

Account for the immunosuppression - These patients are on prednisolone with azathioprine, methotrexate, mycophenolate, tacrolimus, rituximab, IVIG, or cyclophosphamide, often with Pneumocystis prophylaxis. Strict asepsis for every line and block, and expect steroid-driven hyperglycemia.

Steroid myopathy versus flare - High-dose glucocorticoids continued beyond six weeks cause glucocorticoid myopathy, and it looks like the disease. Check the muscle enzymes: a flare raises them, steroid myopathy does not.

Extubate to documented strength - A weak respiratory pump, restrictive lung physiology, and an unprotected airway all land at the same moment. Monitor neuromuscular block quantitatively, extubate awake and sitting, and be prepared to support ventilation afterward.

Dermatomyositis is an acquired immune-mediated inflammatory myopathy driven by a humoral attack on muscle capillaries and arteriolar endothelium. Complement activation forms the C5b-9 membrane attack complex, which deposits on vessel walls; the resulting hypoxic injury picks off the muscle fibers farthest from their blood supply, producing perifascicular atrophy, capillary dropout, and eventual necrosis. Clinically it is subacute symmetric proximal weakness — deltoids, hip flexors, neck flexors — plus characteristic skin disease.

The extramuscular disease is what changes the anesthetic. Interstitial lung disease is present in about a third of patients, oropharyngeal and upper esophageal weakness produces dysphagia and aspiration, cardiac involvement is usually subclinical, and an underlying malignancy is found in 24% of adults.