TY - JOUR
T1 - Effect of Apneic Oxygenation on Tracheal Oxygen Levels, Tracheal Pressure, and Carbon Dioxide Accumulation
T2 - A Randomized, Controlled Trial of Buccal Oxygen Administration
AU - Toner, Andrew J.
AU - Douglas, Scott G.
AU - Bailey, Martin A.
AU - Avis, Hans J.
AU - Pillai, Arani V.
AU - Phillips, Michael
AU - Heard, Andrew
PY - 2019/6/1
Y1 - 2019/6/1
N2 - BACKGROUND: Apneic oxygenation via the oral route using a buccal device extends the safe apnea time in most but not all obese patients. Apneic oxygenation techniques are most effective when tracheal oxygen concentrations are maintained >90%. It remains unclear whether buccal oxygen administration consistently achieves this goal and whether significant risks of hypercarbia or barotrauma exist. METHODS: We conducted a randomized trial of buccal or sham oxygenation in healthy, nonobese patients (n = 20), using prolonged laryngoscopy to maintain apnea with a patent airway until arterial oxygen saturation (Spo2) dropped <95% or 750 seconds elapsed. Tracheal oxygen concentration, tracheal pressure, and transcutaneous carbon dioxide (CO2) were measured throughout. The primary outcome was maintenance of a tracheal oxygen concentration >90% during apnea. RESULTS: Buccal patients were more likely to achieve the primary outcome (P <.0001), had higher tracheal oxygen concentrations throughout apnea (mean difference, 65.9%; 95% confidence interval [CI], 62.6%-69.3%; P <.0001), and had a prolonged median (interquartile range) apnea time with Spo2 >94%; 750 seconds (750-750 seconds) vs 447 seconds (405-525 seconds); P <.001. One patient desaturated to Spo2 <95% despite 100% tracheal oxygen. Mean tracheal pressures were low in the buccal (0.21 cm·H2O; SD = 0.39) and sham (0.56 cm·H2O; SD = 1.25) arms; mean difference, -0.35 cm·H2O; 95% CI, 1.22-0.53; P =.41. CO2 accumulation during early apnea before any study end points were reached was linear and marginally faster in the buccal arm (3.16 vs 2.82 mm Hg/min; mean difference, 0.34; 95% CI, 0.30-0.38; P <.001). Prolonged apnea in the buccal arm revealed nonlinear CO2 accumulation that declined over time and averaged 2.22 mm Hg/min (95% CI, 2.21-2.23). CONCLUSIONS: Buccal oxygen administration reliably maintains high tracheal oxygen concentrations, but early arterial desaturation can still occur through mechanisms other than device failure. Whereas the risk of hypercarbia is similar to that observed with other approaches, the risk of barotrauma is negligible. Continuous measurement of advanced physiological parameters is feasible in an apneic oxygenation trial and can assist with device evaluation.
AB - BACKGROUND: Apneic oxygenation via the oral route using a buccal device extends the safe apnea time in most but not all obese patients. Apneic oxygenation techniques are most effective when tracheal oxygen concentrations are maintained >90%. It remains unclear whether buccal oxygen administration consistently achieves this goal and whether significant risks of hypercarbia or barotrauma exist. METHODS: We conducted a randomized trial of buccal or sham oxygenation in healthy, nonobese patients (n = 20), using prolonged laryngoscopy to maintain apnea with a patent airway until arterial oxygen saturation (Spo2) dropped <95% or 750 seconds elapsed. Tracheal oxygen concentration, tracheal pressure, and transcutaneous carbon dioxide (CO2) were measured throughout. The primary outcome was maintenance of a tracheal oxygen concentration >90% during apnea. RESULTS: Buccal patients were more likely to achieve the primary outcome (P <.0001), had higher tracheal oxygen concentrations throughout apnea (mean difference, 65.9%; 95% confidence interval [CI], 62.6%-69.3%; P <.0001), and had a prolonged median (interquartile range) apnea time with Spo2 >94%; 750 seconds (750-750 seconds) vs 447 seconds (405-525 seconds); P <.001. One patient desaturated to Spo2 <95% despite 100% tracheal oxygen. Mean tracheal pressures were low in the buccal (0.21 cm·H2O; SD = 0.39) and sham (0.56 cm·H2O; SD = 1.25) arms; mean difference, -0.35 cm·H2O; 95% CI, 1.22-0.53; P =.41. CO2 accumulation during early apnea before any study end points were reached was linear and marginally faster in the buccal arm (3.16 vs 2.82 mm Hg/min; mean difference, 0.34; 95% CI, 0.30-0.38; P <.001). Prolonged apnea in the buccal arm revealed nonlinear CO2 accumulation that declined over time and averaged 2.22 mm Hg/min (95% CI, 2.21-2.23). CONCLUSIONS: Buccal oxygen administration reliably maintains high tracheal oxygen concentrations, but early arterial desaturation can still occur through mechanisms other than device failure. Whereas the risk of hypercarbia is similar to that observed with other approaches, the risk of barotrauma is negligible. Continuous measurement of advanced physiological parameters is feasible in an apneic oxygenation trial and can assist with device evaluation.
UR - http://www.scopus.com/inward/record.url?scp=85066834036&partnerID=8YFLogxK
U2 - https://doi.org/10.1213/ANE.0000000000003810
DO - https://doi.org/10.1213/ANE.0000000000003810
M3 - Article
C2 - 31094782
SN - 0003-2999
VL - 128
SP - 1154
EP - 1159
JO - Anesthesia and analgesia
JF - Anesthesia and analgesia
IS - 6
ER -