Tyramine and M.A.O. inhibitors in postural hypotension

Orthostatic hypotension: therapeutic alternatives for geriatric patients

Symptomatic orthostatic hypotension is a serious problem in the elderly because it can precipitate falls and fractures, myocardial infarctions, and strokes. Several disorders may cause symptomatic orthostatic hypotension including age-related changes in physiology, disorders of the autonomic nervous system, drugs, and a decrease in circulating blood volume. Orthostatic hypotension is defined as a fall in systolic pressure of at least 20-30 mm Hg and a fall in diastolic pressure of at least 10-15 mm Hg upon rising, with symptoms of cerebral ischemia. Management includes a search for reversible causes as well as nonpharmacologic and pharmacologic therapies. No single agent has been universally successful in relieving the symptoms of orthostatic hypotension. Trials of single agents or combinations of agents are needed to identify the most appropriate therapy for individual patients.

The diabetic foot: pathophysiology and treatment

The diabetic foot can be classified into the neuropathic foot, characterized by the neuropathic ulcer, the Charcot joint and neuropathic oedema associated with a good circulation, in which neuropathy predominates, and the ischaemic foot in which atherosclerosis is the dominant factor leading to a reduction in blood flow with absent pulses. In the neuropathic foot, blood flow is increased, the vessels are still and dilated as a result of medial wall calcification and there is evidence for arteriovenous shunting. The neuropathic ulcer characteristically develops on the plantar surface following inflammatory autolysis and haematoma formation under neglected callosities. Chiropody is therefore the mainstay of treatment and recurrence is prevented by redistribution of weight bearing forces by moulded insoles in special footwear. Charcot osteoarthropathy is often preceded by fracture which is a further complication of diabetic neuropathy and which precipitates the rapid bone and joint destruction of the Charcot joint. Neuropathic oedema responds to ephedrine with a reduction in peripheral flow and an increase in urinary sodium excretion. The ischaemic foot is characterized by rest pain, ulceration and gangrene. Medical management can be successful in up to 72%, the remainder needing arteriography to assess suitability for arterial reconstruction or angioplasty. In the diabetic leg, atherosclerosis is predominant in the branches of the popliteal artery making arterial reconstruction difficult. Optimum care of the diabetic foot is provided in a diabetic foot clinic where the skills of chiropodist, shoe-fitter and nurse receive full support from physician and surgeon. Many lesions of the diabetic foot are avoidable and thus patient education is the cornerstone of prevention.

Ephedrine: a new treatment for diabetic neuropathic oedema

Peripheral oedema secondary to diabetic neuropathy is poorly understood and difficult to treat. Ephedrine markedly reduced neuropathic oedema in four insulin-dependent diabetics. Mean weight-loss (p less than 0 . 05) after 7 days' treatment was 7 . 43 +/- 4 . 51(SD) kg. The oedema returned (mean weight increase 6 . 33 +/- 1 . 73 kg; p less than 0 . 01) when ephedrine was withdrawn but resolved (weight-loss 4 . 85 +/- 1 . 57 kg; p less than 0 . 01) when ephedrine treatment was repeated. In one patient mean 24 h sodium excretion increased from 177 +/- 5 . 20 mmol before ephedrine to 502 +/- 78 mmol on ephedrine therapy (p=0 . 028). Ephedrine also reduced excessive peripheral blood flow produced by the neuropathy; both arterial diastolic flow and arteriovenous shunting as demonstrated by Doppler blood velocity profiles were reduced and the pulsatility index increased from 2 . 50 +/- 0 . 61 to 4 . 75 +/- 1 . 76 (p less than 0 . 001). Ephedrine continues (12-15 months) to be an effective treatment for neuropathic oedema in these four patients.