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Hyperbaric-oxygen therapy

Multiplace chamber of University of Pisa

For hyperbaric oxygen, pressure is expressed in multiples of the atmospheric pressure at sea level, which is 1 atmosphere. At sea level the blood (plasma) oxygen concentration is 0,3 ml per deciliter.
Tissues at rest extract 5 to 6 ml of oxygen per deciliter of blood, assuming normal perfusion.
Administering 100 percent oxygen at ambient (normobaric) pressure increases the amount of oxygen dissolved in the blood fivefold to 1.5 ml per deciliter, and at 3 atmospheres, the dissolved-oxygen content is approximateley 6 ml per deciliter, more than enough to meet resting cellular requirements without any contribution from oxygen bound to hemoglobin.

RECENT PUBLICATIONS

Hyperbaric oxygen therapy in the management of severe acute anaemia in a Jehovah's Witness. McLoughlin PL, Cope TM, Harrison JC Anaesthesia 1999 Sep;54(9):891-895 A case is described in which a Jehovah's Witness patient who refused blood transfusion suffered massive antepartumhaemorrhage, her haemoglobin falling as low as 2.0 g.dl-1. She was treated on an intensive care unit with intermittent positivepressure ventilation and general supportive measures, pulsed hyperbaric oxygen therapy and recombinant human erythropoietin. **** Clinical review: ABC of oxygen - Hyperbaric oxygen therapy R M Leach, P J Rees, P Wilmshurst. BMJ 1998;317:1140-1143 ( 24 October )

DISEASES FOR WHICH HYPERBARIC OXYGEN THERAPY IS CURRENTLY USED

Diseases for which the weight of scientific evidence supports hyperbaric oxygen as effective therapy
Primary therapy
   Arterial gas embolism
   Decompression sickness
   Exceptional blood-loss anemia
   Severe carbon monoxide poisoning
Adjunctive therapy
   Clostridial myonecrosis
   Compromised skin grafts and flaps
   Osteoradionecrosis prevention

Diseases for which the weight of scientific evidence suggests hyperbaric oxygen may be helpful
Primary therapy
   Less severe carbon monoxide poisoning
Adjunctive therapy
   Acute traumatic ischemic injury
   Osteoradionecrosis
   Refractory osteomyelitis
   Selected problem wounds
   Radiation-induced soft-tissue injury

Diseases for which the weight of scientific evidence does not support the use of hyperbaric oxygen, but for which it may he helpful
Adjunctive therapy
   Necrotizing fasciitis
   Thermal burns

USEFULNESS IN BLOODLESS MEDICINE "Under hyperbaric conditions, the amount of oxygen disssolved in the blood can be sufficient to meet cellular metabolic demands without any contribution from oxygen trasported by hemoglobin. Hyperbaric oxygen has been used successfully to treat hemorragic shock in patients for whom suitable blood was not available or who refused transfusion for religious reasons (1)...
...The physiologic effects of hyperbaric oxygen content on plasma oxygen content make this therapy the tratment of choice in severe anemia when transfusion is not an option"

NEJM 1996; 334:1642-1648

1) Hart GB. HBO and exceptional blood loss anemia. In: Kindwall EP, ed. Hyperbaric medicine practice. Flagstaff, Ariz.: Best, 1994:517-524

CASE REPORT Three patients with acute blood loss anemia (3,8 g/dl; 2,6 g/dl e 6,9 g/dl) and hypovolemic shock

"AII three patients were treated with fluids administered intravenously, iron dextran injection intramuscularly, and hyperbaric oxygen.The hyperbaric oxygen was administered in a single-place chamber at 2 atmospheres absolute for 60 to 90 minutes at each treatment. The number of treatments varied with each patient, depending on his or her condition. When the pulse rate was greater than 120 beats per minute, the blood pressure less than 100 mmHg systolic, and the patient became confused, treatment would be resumed. Fluids (balanced saline solutions) were given intravenously to maintain the central venous pressureat 10 cm H20 and urinary output approximately 50 ml/h. Hematocrit readings and reticuloeyte counts were made every four hours with the use ofmicrotechniques. Hyperbaric treatments were stopped when the vital signs remained within normal range on mild exertion.
Treatment with hyperbaric oxygen resulted in dramatic improvement, with reversal of the signs and symptoms of hypoxia in all three patients.Patient 2 continued to bleed, becoming progressively stuporous until thefourth hospital day (hematocrìt reading 7.5%), when her husband consented to the administration of two units of packed RBC.
No evidence of oxygen toxicity or barotrauma occurred...
Patient 2 received hyperbaric oxygenfor more than 35 hours without pulmonary or cerebral signs of oxygen toxicity.
In addition to volume replacementlother than blood or blood products), hyperbaric oxygen may be used effectively in. the treatment of exceptional blood loss anemia".*

* Estract from JAMA, May 20, 1974, Vol 228, N°8, p.1028-1029

WWW SITES OF HYPERBARIC OXYGEN THERAPY