Hyperoxia in lethal methemoglobinemia: effects on oxygen transport, tissue oxygenation, and survival in pigs.
BACKGROUND
Treatment of severe methemoglobinemia includes the avoidance of methemoglobin-inducing drugs, the application of methylene blue, and the administration of supplementary oxygen. However, the efficacy of the latter on oxygen transport, tissue oxygenation, and survival in the treatment of extreme methemoglobinemia is ambiguous. The objective was to assess whether using hyperoxic ventilation as the sole therapeutic intervention (i.e., ventilation with pure oxygen, Fio2 1.0) improves the short-term (6-hr) survival rate during otherwise lethal methemoglobinemia.


METHODS
Prospective, randomized, controlled study.


METHODS
Experimental animal laboratory of a university hospital.


METHODS
Fourteen anesthetized, mechanically ventilated pigs.


METHODS
After induction of profound methemoglobinemia (60 +/- 2%) by the injection of 15 mg/kg 4-dimethylaminophenol, artificial ventilation either was continued with room air (G 0.21, n = 7) or was changed over to hyperoxic ventilation (G 1.0, n = 7). A constant level of methemoglobinemia was maintained by continuous infusion of 4-dimethylaminophenol throughout a 6-hr follow-up period.


RESULTS
All animals died within the 6-hr follow-up period, but survival time was prolonged in animals ventilated with pure oxygen (G 0.21, 105 +/- 30 mins; G 1.0, 210 +/- 64 mins, p < .05). No differences were encountered between G 0.21 and G 1.0 with respect to the investigated variables of macrohemodynamics, oxygen transport, and tissue oxygenation.


CONCLUSIONS
Hyperoxic ventilation has negligible effects on oxygen transport and tissue oxygenation during lethal methemoglobinemia; nevertheless, survival was increased without severe adverse reactions provoked by hyperoxic ventilation.
Meier
Jens
J
Department of Anesthesiology, Intensive Care Medicine, and Pain Control, Johann Wolfgang Goethe-University Frankfurt am Main, Frankfurt, Germany.
Pape
Andreas
A
Lauscher
Patrick
P
Zwissler
Bernhard
B
Habler
Oliver
O
D000627:Aminophenols; D000818:Animals; D001692:Biological Transport; D001784:Blood Gas Analysis; D005260:Female; D018496:Hyperoxia; D008297:Male; D008708:Methemoglobinemia / Q000139:chemically induced / Q000401:mortality* / Q000628:therapy*; D010100:Oxygen / Q000009:adverse effects / Q000378:metabolism* / Q000493:pharmacokinetics; D010101:Oxygen Consumption; D010102:Oxygen Inhalation Therapy; D011446:Prospective Studies; D011897:Random Allocation; D012121:Respiration, Artificial; D013552:Swine; D014022:Tissue Survival
D000627:Aminophenols; D010100:Oxygen; C020292:4-dimethylaminophenol