Minimum oxygen flow needed for vital support during simulated post-cardiorespiratory arrest resuscitation

Abstract

According to the ERC and the AHA guidelines, FiO₂ should be titrated to achieve an O₂Sat ≥ 94%. The aim of this study was to determine the minimum oxygen flow and time needed to reach an FiO₂ of 0.32 and 0.80 during post-cardiac arrest care. An experimental analysis was performed that consisted of a simulated post-cardiac arrest situation. Different resuscitators were tested and connected to an artificial lung: Mark IV, SPUR II, Revivator Res-Q, O-TWO. The oxygen flow levels tested were 2, 5, 10 and 15 lpm. Bonferroni and Mann–Whitney U tests were used. An FiO₂ of 0.32 or more was obtained using any of the oxygen flow and resuscitators. Only the Mark IV achieved an FiO₂ of 0.80 after a minimum of 75 s ventilating with 2 or 5 lpm. Clinical and statistical differences (p < .05) were found: at 15 lpm it took 35 s to reach an FiO₂ of 0.80 or more for Mark IV (85.6 [0.3]) and Revivator (84.3 [1.5]) compared to 50 s for SPUR II (87.1 [6.4]); at 2 lpm, all of the devices reached an FiO₂ of ≥ 0.32 at 30 s (Mark IV (34.8 [1.3]), Revivator (35.7 [1.5]) and SPUR II (34.4 [2.1]), except for O-TWO, which took 35 s (36.3 [4.3]). Patients could be ventilated with any of the resuscitators using 2 lpm to obtain an FiO₂ of 0.32, although possibly O-TWO would be the last option during the first 60 s. In order to reach an FiO₂ of 0.80, ventilating with 10 lpm should be sufficient, and preferably using Mark IV or Revivator Res-Q. In conclusion, on observing the results of our study, in any possible scenario, it would be advisable to use Revivator Res-Q or Mark IV rather than O-TWO or SPUR II.

Resumen

De acuerdo con las guías de la AHA y la ERC, la FiO₂ a administrarse debería ser aquella con la que se obtuviera una SatO₂ ≥ 94%. El objetivo de este estudio es determinar el mínimo flujo de oxígeno y tiempo necesarios para alcanzar una FiO₂ de 0,32 y de 0,80 durante el manejo posparada cardiaca. Se emplearon diferentes reanimadores, que fueron conectados a un pulmón artificial: Mark IV, SPUR II, Revivator Res-Q, O-TWO. Los flujos de oxígeno probados fueron 2, 5, 10 y 15 lpm. Los test estadísticos aplicados fueron Bonferroni y U de Mann-Whitney. Se obtuvo una FiO₂ ≥ 0,32 con cualquiera de los flujos de oxígeno y reanimadores. Tras un mínimo de 75 s ventilando con 2 o 5 lpm, solo se consiguió una FiO₂ de 0,80 con Mark IV. Se hallaron diferencias clínica y estadísticamente significativas (p < 0,05): con 15 lpm se necesitaron 35 s para alcanzar una FiO₂ ≥ 0,80 con Mark IV (85,6 [0,3]) y Revivator (84,3 [1,5]) comparado con los 50 s que precisó SPUR II (87,1 [6,4]); con 2 lpm, todos los resucitadores alcanzaron una FiO₂ ≥ 0,32 en 30 s(Mark IV (34,8 [1,3]), Revivator (35,7 [1,5]) y SPUR II (34,4 [2,1]), excepto O-TWO, que necesitó 35 s (36,3 [4,3]). Para alcanzar una FiO₂ de 0,32 se podría emplear cualquiera de los resucitadores usando 2 lpm, aunque quizá el menos recomendable sería O-TWO. Si el objetivo fuera una FiO₂ de 0,80, debería bastar con 10 lpm, usando preferiblemente Mark IV o Revivator Res-Q. En conclusión, atendiendo a los resultados de nuestro estudio, ante cualquier situación potencial, sería preferible emplear Revivator Res-Q o Mark IV que O-TWO o SPUR II.