Examples

• Crush injury
  
• Compartment syndromes (increased pressure causing distal ischemia)
  
• Frostbite
  
• Failing surgical flaps of skin and/or muscle
  
• Re-implantation of amputated tissue

Primary Injury

In all of these cases, the primary injury includes:

• Primary tissue destruction
  
• Hypoxia with interrupted blood flow
  
• Oedema, with increased oxygen diffusion distance and capillary collapse
  
• Gradients of hypoxia and ischaemia across the affected tissue
  
• Reperfusion injury, caused by oxygen free radicals, when blood flow is restored.

Secondary injury

Later, secondary injury occurs, including:

• Sludging of blood flow in the capillaries
  
• Formation of contractures
  
• Infection
  
• Compromised wound healing

Patient selection

Objective assessment of these injuries is desirable, so that patients can be selected for Hyperbaric Oxygen treatment with some prediction of success. The most accessible method is by using transcutaneous oxygen (TcPO2) measurements. However, there is no conventional system for this; and cases are selected on a trial-of-treatment basis.

Treatment

Hyperbaric Oxygen:

• Improves oxygen delivery to ischaemic tissues
  
• Reduces oedema, by causing constriction of local arterioles
  
• Accelerates wound healing
  
• Enhances the immune response of hypoxic tissues
  
• Protects against the effects of oxygen free-radicals (if given during reperfusion)
  

The rarity of each of these conditions in any one centre makes it unlikely that many surgeons have seen what can be achieved by using Hyperbaric Oxygen in addition to conventional management. Controlled trials are also difficult to perform, since the ethics of with-holding Hyperbaric Oxygen form the control group are doubtful.

Where Hyperbaric Oxygen helps to prevent the amputation of an extremity, its cost-effectiveness is likely to be high, considering the cost of supporting the patient who is so disabled. The close association of all specialists involved is essential.

Evidence / References

Kindwall E (ed), Hyperbaric Medicine Practice 2nd ed., Chapter 30&31.
Philips JC, Understanding HBOT and its Use in the treatment of Compromised Skin Grafts and Flaps, Plast Surg Nurs. 2005 April/June; 25(2):72-80
William A. Zamboni and Himansu R. Shah. Skin grafts and Flaps (Compromised) HBO Therapy Committee Report 2003 – UHMS, Inc. 2003
Garcia-Covarrubias L, McSwain NE Jr. Van Meter K, Bell RM - Adjuvant HBOT in the management of crush injury and traumatic ischemia: an evidence based approach. Am Surg. 2005 feb;71(2): 144-51.
Strauss M.B. Crush Injuries and skeletal Muscle-Compartment syndromes. HBO Committee Report 2003