By Dr Ananya Mandal, MD
Gangrene is caused by death of tissues due to lack of blood supply. This may be caused by long term diseases that lead to damage to blood vessels like diabetes or due to blood vessel injury like in burns or injuries that give way to deeper tissue infections. These infections cause the part to swell up leading to occlusion of blood vessels.
Diagnosis of gangrene
Diagnosis of gangrene is based on history, physical examination and clinical and laboratory tests.
Medical history may indicate a long term health condition like diabetes, high blood cholesterol, injury in an accident or burn.
Physical examination shows discoloration of the affected area. In case of dry gangrene there is a dried, cool and black appearance of the affected limb.
Wet gangrene on the other hand leads to a swelling of the limb or the affected area. There is evidence of collection of foul smelling pus. (1-5)
Laboratory tests for gangrene
Laboratory tests include;
- Blood tests - Routine blood tests indicate rise in white blood cells. There may be high blood sugar detected in diabetics. Sometimes diabetes may present initially as a case of gangrene. In patients with arteriosclerosis there may be high cholesterol.
- Examination of pus - The pus from the gangrene especially wet gangrene is examined under the microscope. The fluids may be tested for bacteria after staining it with special dyes called Gram stain. Bacteria are stained with a dye and examined under a microscope. The tests are also useful to detect the antibiotics that are potent against the infective organism.
- Blood culture - Blood culture is performed to check for the actual growth of bacteria present in the blood.
- Radiographical imaging - Radioimaging studies include X rays, CT scans and MRI scans. These help detect the blockages in the blood vessels.
- Surgical examination - Surgical examination is needed to confirm a diagnosis of gangrene in any of the internal organs.
Aims of treatment of gangrene
Treatment of gangrene has three important aims (1-5):
- Surgical debridement of removal of the infected tissues so that the infection does not spread via the blood vessels.
- The treatment aims at prevention of the infection and its spread.
- To treat and control the underlying condition that leads to the gangrene to prevent recurrence. A vascular or blood vessel surgery is performed to prevent occlusion and diabetes is controlled to prevent diabetic gangrene.
Antibiotics are used to treat the infection. Oral antibiotic pills and intravenous antibiotics are used. Antibiotics may also be injected into the muscles.
Patients with gas gangrene and infections with Clostridium respond well to antibiotics like:
- metronidazole and a number of cephalosporins
Some patients also require fluids and nutrients. Pain relievers are advised to reduce the pain associated with gangrene.
Surgical debridement involves removal of dead tissue that results from gangrene. This allows for the healthy surrounding tissue to heal and also prevents spread of infection.
Sometimes when the gangrene is severe, where the whole part like the toe or finger or limb is affected, surgical amputation may be the only option available.
Blood vessel surgery
Blood vessel surgery is of two types – bypass surgeries and angioplasty. Bypass surgeries create a diversion. The diversion redirects the flow of blood to bypass the obstruction.
Sometimes a process called angioplasty may be performed where a balloon like device placed into a blocked, artery and inflated to keep the artery open and patent.
Maggot therapy or Biological therapy
Sometimes a novel therapy called Maggot therapy also known as biological therapy may be applied. There are certain maggots or fly larvae that are used for debridement to feed on dead and infected tissue.
The maggot leaves the healthy tissue unaffected. These maggots also release some substances that kill bacteria they also stimulate healing.
These maggots are specially bred in the laboratory with sterilized eggs. The maggots are put onto the wound and it is covered with a gauze and dressed. The dressing is cut off after a few days and the maggots are removed.
Alternative treatments of gangrene
Hyperbaric oxygen (HBO) therapy is an alternative treatment. Since gangrene is caused by lack of oxygen this may help in healing.
The patient is placed within a special chamber and the chamber is filled with pressurised air and a plastic hood with pure oxygen. The plastic is placed over the gangrenous part. It causes the oxygen to dissolve into the blood and more oxygen can be delivered into the affected area to speed up healing.
HBO therapy prevents further damage by the bacteria and prevents production of toxins by the existing bacteria.
Prevention of gangrene
Prevention of gangrene involves keeping blood sugar and cholesterol under control. Patient is advised a healthy balanced diet, regular exercise and good foot and limb care.
Diabetics should get their feet checked by podiatrists at least once a year for prevention of foot ulcers that may turn into gangrene.
Patient should avoid walking barefoot, avoid harsh chemicals over foot and other extremities, keep feet clean and dry and avoid burns over the foot.
Stopping smoking can cut down risk of gangrene. Smoking leads to blockage of small arteries and loss of blood supply to fingers and toes known as peripheral arterial disease.
Similarly excessive alcohol leads to high cholesterol and arteriosclerosis and blockage of arteries.
Reviewed by April Cashin-Garbutt, BA Hons (Cantab)