Rojas CL, Vidal AE, Cerón DUW

Language: Spanish
References: 10
Page: 21-25
PDF size: 230.61 Kb.

ABSTRACT

Introduction: the PaO₂/FiO₂ ratio adjusted to barometric pressure is used to assess oxygenation in respiratory failure; however, it does not take PaCO₂ into account, unlike the PaO₂/FAO₂ ratio (PaO₂ divided by the alveolar fraction of oxygen). Objective: to evaluate the agreement between PaO2/FiO₂ and PaO2/FAO₂. Material and methods: observational, ambispective, cross-sectional and analytical study in patients older than 18 years, under invasive mechanical ventilation with respiratory failure and with different PaCO₂ values. Results: agreement was analyzed in 64 gasometric measurements taken at admission and when the highest PaCO₂ was documented, of 32 patients. The Bland and Altman analysis showed a mean of the differences (bias) of 13 and a 95% limit of agreement, between 54 and -24. Agreement is better when PaO₂/FiO₂ is greater than 150. Twenty two percent of the measurements did not agree in the assignment to groups with mild, moderate, or severe hypoxemia. Conclusions: there is moderate agreement between PaO₂/FAO₂ and PaO₂/FiO₂; however, in patients with severe hypoxemia, agreement is better. In patients with PaO₂/FiO₂ ≥ 150, hypercapnia partly explains the low agreement. PaO₂/FAO₂ is possibly a better way to assess the degree of oxygenation disturbance.

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