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Amer et al. Metastatic myonecrosis

anxious, restless, apprehensive, and tachycardic behind this treatment is that, due to the hypovascularity
[2]
but normotensive. Gas in the tissue is a late sign; [2,6,15] of the infected site, an extremely high concentration
it may be absent altogether. [2,5,14] Gas in the tissue is of dissolved oxygen is necessary to raise the tissue
neither a sensitive nor a specific sign of clostridial pO . Hyperbaric oxygen is believed to reduce the
2
[8]
infection. It can be found with E. coli, Streptococcus, general toxicity of circulating clostridial toxins and to
[5]
[2]
Proteus, Enterococcus, Staphylococcus, Klebsiella, limit the spread of infection. In addition, hyperbaric
Pseudomonas, and Bacteroides species, particularly in oxygen reduces the spore granulation rate and aids
patients with diabetes. The skin shows bronze coloration eradication of the organism both in vitro and in
around the area involved, [2,15] and bullae develop that vivo. [15] The α toxin production is suppressed at an
are filled with mousy-smelling fluid containing gram- oxygen tension of 250 mmHg. This is achieved by the
[8]
positive rods. Patients usually experience profound production of oxygen free radicals. Hyperbaric oxygen
metabolic acidosis, and hemolysis caused by the is also believed to protect the viability of healthy tissue
exotoxins may cause fever, hypotension, disseminated surrounding an area of progressive necrosis. The
intravascular coagulation, and renal failure. accepted treatment now is five hyperbaric sessions at
three atmospheric pressure within the first 48 h, up to
[3]
Diagnostic feature a total of seven to ten sessions.
Gram stain from the bullae renders gram-positive
bacilli without spores and very low leukocyte count. Surgical treatment
[6]
The skin around the bullae is purple, reflecting the Surgery remains the critical life-saving intervention and
[8]
vascular compromise that results from diffusion of should not be delayed in the interest of transferring a
[7]
bacterial toxins in the surrounding tissues. X-ray of the patient to a facility with hyperbaric oxygen. In the
affected limb reveals soft-tissue gas [2,3] [Figure 1]; absence of adequately debrided wound, antibiotic
[15]
however, CT scan has been shown to be a more will not prevent gas gangrene. Surgery ranges
sensitive test. Clinically, the muscle looks dark from simple fasciotomy to radical debridement/
[13]
[18]
[3,4]
and cooked, and it does not contract when incised. amputation. In a study on dogs, Domello showed
[5]
Other lab results may reveal evidence of hemolysis, that surgery alone or with hyperbaric oxygen left no
hyperbilirubinuria, hyperkalemia, and anemia as a survivors, whereas surgery with antibiotics left 70%
result of the release of toxins. [3] survivors. Antibiotics alone left 50% survivors.
Management There is a better outcome when patients undergo
Initial treatment involves high oxygen concentration one hyperbaric session prior to initial debridement,
and aggressive volume expansion with intravenous and further debridement can be planned between
subsequent hyperbaric treatments. The deferment has
isotonic crystalloid fluid. Volume status should be the following advantages:
[3]
monitored via urinary output and central venous
pressure. Blood should be given sparingly, since it 1. The patient has better improved general condition.
will be hemolyzed rapidly. Brummelkamp [16,17] advised 2. Surgery is limited to the removal of necrotic tissue
delay in transfusion till exotoxin production and alone.
hemolysis are brought under control with hyperbaric 3. Necrotic tissue is better demarcated. [2]
oxygenation. Vasopressins should be avoided, and
severe acidosis should be treated with bicarbonate. When fasciotomy is necessary, the procedure should
Antibiotics should be started, with penicillin G being the always be performed prior to hyperbaric O treatment.
[7]
2
antibiotic of choice, [4,5,7,13,15] given in high doses of 20- Even if the diagnosis is in doubt, it is better to begin
40 million units. Alternatively, in the event of penicillin antibiotic and hyperbaric oxygen treatment promptly
allergy, cephalothin, clindamycin, or metronidazole can rather than to take a wait-and-see approach. Antitoxin
[15]
be used. Sodium penicillin is preferable to potassium has been shown to be of no value in preventing the
penicillin [2,3,13] because the patient is already at risk of spread of clostridial infection.
hyperkalemia from tissue breakdown.
Finally, patients who do survive should be screened for
The use of hyperbaric oxygen for the treatment of colonic or hematologic malignancy. [4]
gas gangrene remains controversial. Brummelkamp
[7]
reported that 21 (81%) of 26 patients with clostridial In conclusion, clostridial myonecrosis is a rapidly
infection who received hyperbaric oxygen survived. [8,16] spreading infection which is fatal unless recognized
Results from more recent study showed survival of early. Purple discoloration in a limb of a sick patient,
70% of patients treated with hyperbaric oxygen and with or without crepitation, should be taken as a
30% not treated with hyperbaric oxygen. The rationale sinister sign, and early aggressive treatment with
Journal of Cancer Metastasis and Treatment ¦ Volume 2 ¦ October 21, 2016 405