C MacFarlane, FJ Cronje, CA Benn. Hyperbaric Oxygen in Trauma and Surgical Emergencies

Hyperbaric oxygen therapy (HBO), that is the administration of 100% oxygen delivered under pressure, has a beneficial effect in several surgical conditions. Its use has been assessed and audited and its pharmacological effects demonstrated. It is appropriate for use in several acute surgical conditions as evidence-based therapy. These are: • Gas Gangrene • Crush Injuries, Compartment Syndromes & Acute Traumatic Ischaemias • Enhancement of Healing in Selected Problem Wounds • Exceptional Bloodloss Anaemia • Necrotising Soft Tissue Infections • Compromised Skin Grafts & Flaps • Thermal Burns HBO therapy suffers from previous inappropriate use, lack of knowledge, and scarce hyperbaric facilities. Hyperbaric therapy, when properly supervised by a physician trained in its use, working closely with a surgeon, and ethically used for appropriate indications, can be a useful adjunct to surgical practice. Military surgeons may be in a situation in which they can utilize HBO in acute surgical conditions and trauma. They are urged to identify HBO facilities, both fixed and portable, and to establish communication with hyperbaric therapy colleagues. Introduction Hyperbaric Oxygen therapy implies the administration of 100% oxygen breathed within an environment of increased pressure and delivered to the tissues, via the circulation, to achieve a therapeutic benefit. With the exception of arterial gas embolism, carbon monoxide poisoning and decompression sickness, where HBO is the definitive treatment, it is otherwise employed as an adjunctive therapy in surgical practice. In spite of indiscriminate use in the past, hyperbaric oxygen therapy has now become more logical and evidence based when administered by ethical and experienced medical practitioners. Military surgeons, some of whom have a background of diving medicine, are perhaps in a better situation to both understand and apply hyperbaric oxygen than some of their civilian colleages, since they may have access to formal hyperbaric facilities, but also may be able to utilise facilities primarily provided for the treatment of diving injuries. Even small, portable emergency chambers can be used for this purpose in emergency cases, providing there is understanding of the physiological and pathological processes involved and advice available from a hyperbaric physician in assessing the indications and for supervising therapy(1). This lends itself to a telemedicine linkup. Many surgeons remain unaware of the potential benefits of hyperbaric oxygen therapy. As far as military surgery is concerned, if war injuries are being received into base hospitals for example, HBO has been shown to be of value in cases of successful vascular repair with persistent signs of peripheral ischaemia(2). HBO has an established place in several acute surgical conditions particularly trauma. In the United States a significant number of trauma centres have hyperbaric chambers in close association (eg. Shock Trauma, Baltimore). Mode of Action HBO provides a pressure-related increase in plasma-borne oxygen. This increases total blood oxygen content by 20 25%(3) and markedly improves free (i.e. dissolved) oxygen delivery to tissues, increasing the diffusion distance from the capillaries into tissues several fold(4). At these increased tissue levels, oxygen initiates a series of distinct physiological and pharmacological effects. The therapeutic range for oxygen therapy is an inspired oxygen partial pressure (piO2) of 1.5 to 3 times atmospheric pressure (ATA). Higher oxygen pressures (>3 ATA) are too toxic for clinical use. There are five groups of therapeutic mechanisms attributed to hyperbaric oxygen use: • Hyperoxygenation • Vasoconstriction • Neovascularisation (Angiogenesis) • Altered Cellular Function • Pressure and Gas Gradients Campbell MacFarlane, Hons. BA, BSc (Hons), MBChB, MMed (Surg), PhD, FRCS (Ed), FRCS (Eng), FACS, FACEM (Hon.), FFAEM, MRACMA, DMCC Gauteng Health Department Emergency Medical Services Johannesburg Honorary Consultant, Johannesburg Hospital Trauma Unit University of the Witwatersrand E-mail: [email protected] Frans J Cronjé, BSc (Hons) Aerosp Med, MBChB Hyperbaric Unit, Eugene Marais Hospital, Pretoria Carol-Ann Benn, MBBCh, FCS(SA), DIP.PEC(SA) Consultant Surgeon, Baragwanath Hospital, Johannesburg, University of the Witwatersrand J R Army Med Corps 2000; 146: 185-190 Hyperbaric Oxygen in Trauma and Surgical Emergencies C MacFarlane, FJ Cronje, CA Benn group.bmj.com on June 19, 2017 Published by http://jramc.bmj.com/ Downloaded from