1. 1 Hyperbaric Oxygen Therapy in Necrotizing soft tissue infection Wei-Hsiu Hsu, MD Assistant Professor Department of Orthopaedic Surgery Chang Gung Memorial Hospital at Chia Yi

2. 2 Definition of HBO Breathing 100 % O 2 intermittently Chamber pressure increased at least 1.4 atmosphere absolute

3. 3 Necrotizing soft tissue infection Rapidly progressive Life-threatening, Deepseated soft tissue infection Necrosis –Fascia –Subcutaneous tissues..

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6. 6 Bacteria Secretion Endotoxins: Shock, CV depression Exotoxins: Protease enzymes: degrade fat and the extracellular matrix

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8. 8 Fact 500 to 1500 cases reported in the United States annually Mortality of 20% to 40% Significant morbidity, multiple surgical de’ bridements and possibly even amputation

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10. 10 Treatment of NF Aggressive, early surgical de’bridement Broad-spectrum antibiotic therapy directed at presumed causative agents. Surgical treatment includes the excision of necrotic fascia, compromised skin, and subcutaneous tissue.

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12. 12 What is the additional help? HBO in NF : complimentary and adjunctive role

13. 13 Type I NF Co-morbidity: peripheral vascular disease, immune compromise, diabetes, or surgery inciting factor is a wound Polymicrobial disease. –Staphylococcus aureus –Escherichia coli, –Bacteroides fragilis, –and various species of Streptococci, Enterococci, Peptostreptococcus, Prevotella,Porphyromonas, and Clostridium AND VIBRIO SPP AND AEROMONAS

14. 14 Type II NF 10% to 15% of cases Monomicrobial form Group A Streptococcus Community-associated methicillin-resistant S aureus (MRSA) spontaneously in apparently healthy people who have minimal or no prior trauma

15. 15 Clinical finding Early Pain Cellulitis Pyrexia Tachycardia Induration Skin anesthesia

16. 16 Clinical finding Late Severe Pain Skin Discoloration(balck or purple) Blistering Haemorrhage Crepitus Dishwater pus SIRS Multiorgan failure

17. 17 Laboratory Findings Leucocytosis Acidosis Altered coagulation profiles Hypoalbuminemia Abnormal Renal function

18. 18 Image finding X ray: soft tissue gas CT/MRI: Delineate the extent of disease Incisional exploration: Tissue culture/ Tissue proof

19. 19 Rationale for HBO Mechanisms of antimicrobial effect Mechanisms of neovasculization

20. 20 Mechanisms of antimicrobial effect Enhancement of leukocyte-killing activity Bacterial growth suppression in hyperoxic tissues Enhancement of antibiotic effects Improvement in tissue repair Effects on anaerobic bacteria

21. 21 Enhancement of leukocyte-killing activity Granulocytes kill microorganisms –Oxygen-independent –Oxygen-dependent – The oxygen-dependent system consumes large amounts of molecular oxygen to produce an ‘‘oxidative burst’’ after phagocytosis of offending pathogens.

22. 22 Oxidative Burst oxygen radicals –hydroxyl radicals –Peroxides –superoxide. Proportional to the amount of available oxygen retarded in a hypoxic environment.

23. 23 Bacterial growth suppression in hyperoxic tissues Healthy normoxic wounds with adequate perfusion are highly resistant to infection In tissues: oxygen tension < 30 mm Hg, an established bacterial infection quickly destroyed the tissue synergistic effect between a hyperoxic environment plus antibiotics

24. 24 Enhancement of antibiotic effects Aminoglycosides Antimetabolite agents –Trimethoprim –sulfamethoxazole, –Sulfasoxazole

25. 25 Improvement in tissue repair Poorly vascularized, ischemic tissue : decreased healing response and increased susceptibility to infection HBO : in conjunction with standard treatment protocols, clearing of the infection and wound closure are significantly improved.

26. 26 Effects on anaerobic bacteria Anaerobic bacteria: susceptible tot free radicals and other toxic oxygen species. The enhancement of production of these endogenous free radicals by granulocytes is the primary mechanism by which HBO can be bacteriocidal to anaerobic organisms.

27. 27 Angiogenesis Marx et al 1999

28. 28 Availability of oxygen Under hyperbaric conditions, the PaO2 at 2.5 ATA approaches 2000 mm Hg. This pressure is high enough to generate 5.4 vol% of dissolved oxygen Hyperoxygenated plasma can transport oxygen to areas that are inaccessible to red cells,

29. 29 Tissue oxygen tension measurement

30. 30 Save the Gray Zone

31. 31 Treatment of NF aggressive, early surgical de’bridement broad-spectrum antibiotic therapy directed at presumed causative agents. HBO in NF : complimentary and adjunctive role Surgical treatment includes the excision of necrotic fascia, compromised skin, and subcutaneous tissue.

32. 32 Hyperbaric oxygen treatment protocol for necrotizing fasciitis Pressure: HBO treatments started at 2.0– 2.5 ATA Duration: 90–120 minutes Frequency: Treatment is initially done twice daily Treatments: Treatments can continue until clinical improvement is maximized. Use review: The continued use of HBO should be reviewed after 30 treatments.

33. 33 Results Mortality: 34% to 11.9 % Limb salvage

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36. 36 Issue of HBO never substitute for the primary interventions Never delay the planned surgical treatment

37. 37 Future direction More aggressive HBO intervention  Critical care in HBO Chamber Magnetic Infusion pump Mechanical ventilation Risk Control

38. 38 Medical monitor system from HAUX TcPo2/TcPco2 X 2 NIBP X 1

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40. 40 Risk of HBO Fire hazard General features –Claustrophobia –Reversible myopia –Fatigue –Headache –Vomiting

41. 41 Risk of HBO Barotrauma –Ear damage –Sinus damage –Ruptured middle ear –Lung damage Oxygen toxicity –Brain: Convulsion and psychological –Lung: Pulmonary edema, hemorrhage Respiratory failure due to pulmonary fibrosis

42. 42 Risk of HBO Decompression Illness Pneumothorax Gas emboli

43. 43 Contraindication Absolute: Untreated pneumothorax Relative: –URI –Emphysema with CO 2 retension –Pulmonary lesion in CXR –Uncontrolled high fever –Claustrophobia –Seizure disorder –Malignant disease

44. 44 Thanks for your attention