In some cases of blood loss in which blood products are refused for religious reasons or in cases of severe hemolysis or a rare blood type for which no adequate cross-match may be found, HBOT can provide temporary support of tissue oxygenation. Treatment has been continued for up to 10 days. Patients with as little a 1gram of hemoglobin have been supported with HBOT. Enough O2 can be dissolved in plasma at 3 ATA to support life.