RTO MP-062 / HFM-050 - FTP Directory Listing - Nato

KN2-6
hemorrhagic shock sets in motion events that are not corrected by transfusion alone. The most prominent
events are the elaboration of tumor necrosis factor (TNF) and interlukin-6 (IL-6), which are associated
with increased mortality. 53 In a zymosan model simulating septic shock there is increased production of
TNF and nitric oxide metabolites (NOx) that are associated with increased mortality. 54 In both the
hemorrhagic and septic shock model HBO reduces TNF, IL-6, and NOx production and most importantly,
it improves survival.
CATEGORY III – THERMAL BURNS
A substantial number of animal studies have clarified the benefits of HBO for the management of
moderate and severe burns. These include shortened healing time, reduction of infection, reduced fluid
requirements and reduced burn evolution from partial to full thickness loss. Clinical studies have affirmed
much of the animal data. Cianci and others have documented shortened hospital stays, decreased fluid
requirements, and reduction in surgical procedures. 55,56 Some burn centers are now following a strategy
of early and aggressive surgical debridement. When this approach is used, the benefits of HBO are
obscured. In a prospective trial by Brannan et al HBO failed to show any reduction in length of stay or
surgical procedures. 57 However, both groups received very early and aggressive burn excision, which did
not permit a clear delineation of HBO’s salvage effect for “transitional” tissue. It should also be noted
that early radical burn excision is very difficult for selected locations such as the face and hands and may
not be possible in a mass casualty situation.
SUMMARY
Given that oxygen is one of the fundamental cornerstones of life, it is not surprising to find that it behaves
in a multidimensional capacity. During acute microcirculatory failure it functions simply as a nutrient or
metabolite. In this capacity, HBO must be provided several times per day. When there is a transient
interruption of tissue perfusion, we find that high dose oxygen prevents the secondary deterioration of the
microcirculation by containing reperfusion phenomenon. Likewise when the stress is more global such as
hemorrhagic shock or septic shock, we again find a beneficial role of HBO in terms of reduced cytokine
production and improved survival. Under these circumstances acute intervention is also important,
however the requirements for HBO may be as few as three to six treatments. For the more chronic
situation of a nonhealing wound associated with regional hypoxia, documented by oxymetric studies, we
find that HBO behaves more as a cell signal requiring only once a day dosing.
For combat casualty management, logistical and operational issues have limited the widespread use of
HBO. The recent development of the hyperlight chamber by the United States Airforce will permit a
substantially more rapid deployment of this effective therapy in the theater of operation.
References:
1 Hampson NB: Hyperbaric Oxygen Therapy: 1999 Committee Report. Undersea and Hyperbaric Medical
Society; 10531 Metropolitan Avenue. Kensington, Maryland 20895-2627.
2 Boerema I, Meyne NG, Brumelcamp WK, et al: Life without blood (A study of the influence of high atmospheric
pressure). J Card Surg 1960;1:133-146.
3 Krogh A. The number of distribution capillaries in muscle with calculations of the oxygen pressure head
necessary for supplying the tissue. J Physiol 1919; 52: 409-415.
4 Bird AD, Tefler AMB: Effect of hyperbaric oxygen on limb circulation. Lancet 1965355-356.
5 Hunt TK, Pai MP. The effect of varying ambient oxygen tensions on wound metabolism and collagen synthesis.
Surg Gyn Ostet 1972; 135:561.
6 Knighton DR, Silver IA, Hunt TK: Regulation of wound healing angiogennesis: effect of oxygen gradients and
inspired oxygen concentration. Surgery 1981;90:262-270.
7 Hehenberger K, Brismar K, Lind F, et al. Dose-dependent hyperbaric oxygen stimulation of human fibroblasts.
Wound Rep Regen 1997; 5:147-50.