Clostridial Myonecrosis (Gas Gangrene)

Objectives
Diagnosis
Criteria for HBO therapy
Work-up considerations
Treatment
Suggested treatment threshold
ICD 10 codes
Level of evidence

Objectives

To provide a bacteriostatic level of tissue oxygenation. Inhibit lethal alpha toxin production. To prevent ongoing necrosis and tissue loss. Improve host defence mechanisms. Augment antibiotic therapy. Help demarcate necrotic tissue from potentially viable tissue to enable more effective and conservative surgery.

Diagnosis

History of traumatic/ischemic wound. Excruciating pain and signs of systemic toxicity disproportionate to extent of infection/injury. Spreading cellulitis, orange-copper skin discoloration, blistering, serous/watery exudates with sweet/’mousy’ odour, +/- crepitation due to gas in tissues (on clinical exam or seen on x-ray), necrotic muscle tissue. Gram positive rod diagnostic on wound exudates or smear.

Criteria for HBO therapy

Clinical diagnosis of expected gas gangrene.Gram positive rods in exudates/on smear. Gas in tissue clinically or on x-ray(NOTE: Tissue gas is neither pathognomonic of gas gangrene nor is the absence of gas evidence to the contrary) Clostridiumperfringens isolated. Clinical & histological picture consistent with clostridial myonecrosis

Work-up considerations

1. Patient needs to be referred from or discussed with surgical specialist & critical care specialist.
2. Medical history & physical examination.
3. Lab work in order – bloods & cultures, including aerobic and anaerobic.
4. If Clostridium septicum is identified, then occult GIT malignancy should be excluded.
5. ECG.
6. X-ray’s – chest & affected soft tissue.
7. Wound Photography (consented).
8. Transcutaneous oxygen measurements if appropriate.
9. Optimal stabilisation & maintenance of medical treatment i.e. IVI fluids, analgesia, appropriate IVI antibiotics, urinary catheter, NG tube, central lines, glucose control, etc.
10. Timing of HBOT. Clinical experience supports pre-op HBOT because of the              advantages of reduced patient toxicity, improved operative risk & improved tissue demarcation with reduced tissue loss. However, if transfer to HBOT unit will result in significant delay in surgical decompression/ debridement of devitalised tissue, then the patient should go to the OR first and then be treated with HBOT as soon as possible thereafter.
11. Consider emergency myringotomies or placement of ventilation tubes with first surgery.
12. Avoid petroleum based dressings or ointments.
13. Signed informed consent for HBOT.
14. Comply with appropriate infection control measures.

Treatment

1. HBO at 3.0 ATA for 90 minutes with either one 10 minute air break after 45 minutes or two 5 - 10 minute air breaks after 30 minutes.
2. Treatment schedule: First treatment ASAP, then q 8 hourly for 1st 24 hours, then q 12 hourly for 48 hours. Usually 7 treatments with the first 72 hrs.
3. If patient experiences any signs or symptoms due to central nervous system oxygen toxicity, consider treating patient at 2.5 ATA with shortened oxygen periods (not less than 15 min) and more regular or longer air breaks (up to 15 min).

Suggested treatment threshold

7 treatments, with a range of 5 – 10 treatments

ICD 10 codes

• A48.0 - Gas gangrene
• B96.7 - Clostridium perfringens as the cause of diseases classified to other chapters

Level of evidence

• Level C.
• All authorities consider it unethical to subject this indication to a randomised controlled trial with a non-treatment control group.
• MEDICAL SCHEMES ACT, 1998 (ACT NO. 131 OF 1998)
• Annexure A – Prescribed Minimum Benefit:
  • CODE: 227S; DIAGNOSIS: ANAEROBIC INFECTIONS LIFE THREATENING; TREATMENT: MEDICAL MANAGEMENT; HYPERBARIC OXYGEN