[Apnea testing to establish death based on brain criteria].
BACKGROUND
The apnea test provides one of the most important criteria for the diagnosis of death by brain criteria, nevertheless although the absence of spontaneous respiration is a crucial point in the diagnosis of the death, we must point out, that still, there are not standardized criterion to perform this test.


METHODS
The lack of uniformity at the moment of carrying out this test in our country is due to the use of time as an indirect estimate of the PCO2 levels instead of the actual measurement of the blood level of this gas. This paper reviews the recommendations about this procedure published in the medical literature. It also remarks the most interesting physiopathological aspects related to this test.


CONCLUSIONS
At present, the literature does not provide evidence to favor one method over the other however, it seems generally accepted that a positive apnea test requires a level of PCO2 equal or greater than 60 mmHg. Optionally, it is possible to consider 20 mmHg above the starting arterial PCO2 level. It seems clear that this aspect is more important than the duration of the test. The fears about hypoxemic damage during the apnea test are not support by the information found in the literature. It seems that the respiratory like movements do not exclude the diagnosis of death by brain criteria.
Tellería-Díaz
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Unidad de Cuidados Intermedios, Hospital General Docente Enrique Cabrera, La Habana, Cuba.
D001049:Apnea / Q000175:diagnosis*; D001926:Brain Death / Q000175:diagnosis*; D006801:Humans; D000860:Hypoxia / Q000175:diagnosis