Gangrene is the term used to describe the decay or death of an organ or tissue caused by a lack of blood supply. It is a complication resulting from infectious or inflammatory processes, injury, or degenerative changes associated with chronic diseases, such as diabetes mellitus.
Gangrene may be caused by a variety of chronic diseases and post-traumatic, post-surgical, and spontaneous causes. There are three major types of gangrene: dry, moist, and gas (a type of moist gangrene).
Chronic diseases, such as diabetes mellitus, arteriosclerosis, or diseases affecting the blood vessels, such as Buerger’s disease or Raynaud’s disease, can cause gangrene. Post-traumatic causes of gangrene include compound fractures, burns, and injections given under the skin or in a muscle.
Gangrene may occur following surgery, particularly in individuals with diabetes mellitus or other long-term (chronic) disease.Some surgical procedures end up causing gangrene. Approximately two-thirds of cases affect the extremities, and the remaining one-third involve the abdominal wall.
Areas of either dry or moist gangrene are initially characterized by a red line on the skin that marks the border of the affected tissues. As tissues begin to die, dry gangrene may cause some pain in the early stages or may go unnoticed, especially in the elderly or in those individuals with diminished sensation to the affected area. Initially, the area becomes cold, numb, and pale before later changing in color to brown, then black. This dead tissue will gradually separate from the healthy tissue and fall off.
Except in cases where the infection has been allowed to spread through the blood stream, prognosis is generally favorable. Anaerobic wound infection can progress quickly from initial injury to gas gangrene within one to two days, and the spread of the infection in the blood stream is associated with a 20-25% mortality rate. If recognized and treated early, however, approximately 80% of those with gas gangrene survive, and only 15-20% require any form of amputation. Unfortunately, the individual with dry gangrene most often has multiple other health problems that complicate recovery, and it is usually those other system failures that can prove fatal.
* Occurrence is not age specific.
* Diabetic peripheral vascular disease and other chronic immunocompromised states that can predispose individuals to gas gangrene are more prevalent in older populations.
* Incubation period usually is fewer than 3 days, with rapid onset of symptoms. Infection can advance as much as 1in/h.
* Pain commonly is out of proportion to physical findings.
* Progression to toxemia and shock can be rapid.
* Patients who develop nontraumatic gas gangrene usually are immunocompromised.
* Gas gangrene is highly associated with hematologic and gastrointestinal malignancies.
* Additional risk factors include diabetes mellitus, peripheral vascular disease, drug abuse, and alcoholism.
Prevalence and incidence
The disease occurs rarely in men and women under 55 years of age but affects 5% of those aged 55 to 74 years. Prevalence increases rapidly with age and it is slightly more common in men than women. It is more frequent in the lower social classes, mostly due to higher levels of smoking. The main risk for claudicants is a two to threefold higher mortality than non-claudicants, mostly due to associated coronary heart disease.
Critical limb ischaemia has an estimated incidence of 500-1000 per million population per year. Twenty five percent have an amputation and 50% are dead within 5 years. Asymptomatic peripheral arterial disease causing a major disruption to blood flow in the legs is common, affecting 8% of 55- to 74-year-olds; a further 17% have minor asymptomatic disease. These individuals are also at increased risk of acute coronary events and stroke. The most important form of symptomatic aneurysm is rupture. The annual incidence is about 17 per 100,000. The death rate due to aortic aneurysm in 1996 was 24.1 per 100,000 in men and 13.8 per 100,000 in women. The prevalence of asymptomatic aneurysm is about 5% in men aged 65 to 74 years. The male:female ratio is about 3:1 and the prevalence increases steeply with age.
How common is PVD? PVD affects about 1 in 20 people over the age of 50, or 10 million people in the United States. More than half the people with PVD experience leg pain, numbness or other symptoms – but many people dismiss these signs as “a normal part of aging” and don’t seek medical help. Only about half of those with symptoms have been diagnosed with PVD and are seeing a doctor for treatment.
Incidence of Peripheral Vascular Disease(PVD)
* PVD affects 10 million people in the United States including 5% of the over 50 population
* Only a quarter of PVD sufferers are receiving treatment
* Symptomatic constitues 50% of cases (5 million)
* Of these, 2.5 million go undiagnosed
* Of the 2.5 million diagnosed cases, 2.1 million are medically managed (e.g. exercise)
Who is at risk for PVD?
As many as 8 million people in the U.S. may have PVD. The disease affects everyone, although men are somewhat more likely than women to have PVD. Those who are at highest risk are:
* over the age of 50
* people who do not exercise, or
* people who have high blood pressure or high cholesterol.
A family history of heart or vascular disease may also put you at higher risk for peripheral vascular disease.