Efficacy of preoxygenation using tidal volume and deep breathing techniques with and without prior maximal exhalation

Abstract

Purpose:We evaluated the influence of prior maximal exhalation on preoxygenation in 15 adult volunteers using tidal volume breathing (TVB) for five minutes and deep breathing (DB) for two minutes with and without prior maximal exhalation.Methods: Inspired and end-tidal oxygen, nitrogen and carbon dioxide were monitored continuously and recorded during room air breathing and at 30-sec intervals during 100% oxygen TVB or DB (rate of 8 breaths·min -1 ).Results: Tidal volume breathing with prior maximal exhalation resulted in an end-tidal oxygen concentration (ETO 2 ) slightly higher (P = 0.028) at 0.5 and 1.0 min as compared with TVB without prior maximal exhalation at the same time periods. Regardless of whether TVB was preceded by maximal exhalation or not, 2.5 min was required to reach a mean ETO 2 value of 90% or higher. With DB, there were no differences in ETO 2 values at any time period and 1.5 min was required to reach an ETO 2 of 90% or greater, with or without prior maximal exhalation. Conclusions:Maximal exhalation prior to TVB slightly steepens the initial rise in ETO 2 during the first minute, but confers no real benefit if maximal preoxygenation is the goal. Maximal exhalation prior to DB has no added value in enhancing preoxygenation.

Scandinavian clinical practice guidelines on general anaesthesia for emergency situations

“…65 In the other study, using healthy volunteers, maximal exhalation before tidal volume breathing produced a significantly faster increase in the end-expiratory oxygen concentration than oxygenation with tidal volume breathing alone. 66 However, the conclusion from the most recent study in 15 healthy volunteers was that preoxygenation with maximal exhalation before tidal volume breathing for 5min slightly steepens the initial rise in ETO 2 during the first minute, but confers no real benefit if maximal pre-oxygenation is the goal 67 [III]. In this study, maximal exhalation before deep breathing for 2 min had no added value in enhancing pre-oxygenation.…”

“…In this study, maximal exhalation before deep breathing for 2 min had no added value in enhancing pre-oxygenation. 67 Pre-oxygenation combined with ventilation or with positive end-expiratory pressure (PEEP)…”

Preoxygenation, Reoxygenation, and Delayed Sequence Intubation in the Emergency Department

“…When possible, a maximal exhalation preceding the tidal volume breathing improves preoxygenation (6,7). The non-rebreather mask (NRB), though the routine oxygen source, provides only 65-80% of fiO 2 (8).…”

Techniques of preoxygenation in patients with ineffective face mask seal

“…Rapid techniques of pre-oxygenation (VC breaths) may result in rapid arterial oxygenation without a significant increase in the tissue oxygen stores and hence result in more rapid haemoglobin desaturation during subsequent apnea than would a longer period of TV pre-oxygenation. [14] Storage of oxygen in the tissue is more difficult to assess but assuming that Henry's law applies and that the partition coefficient for gases approximates the gas water coefficients, breathing 100% oxygen for 3 min or more significantly increases tissue oxygen stores. [814] Deep breathing for a 2 min period is the practical upper limit and if extended beyond 2 min, can lead to hypocapnia causing an increase in oxygen consumption, cerebral vasoconstriction, dizziness and nausea.…”

“…[14] Storage of oxygen in the tissue is more difficult to assess but assuming that Henry's law applies and that the partition coefficient for gases approximates the gas water coefficients, breathing 100% oxygen for 3 min or more significantly increases tissue oxygen stores. [814] Deep breathing for a 2 min period is the practical upper limit and if extended beyond 2 min, can lead to hypocapnia causing an increase in oxygen consumption, cerebral vasoconstriction, dizziness and nausea. [9]…”