Bag-mask ventilation and the power of preoxygenation

Crystal Lam, MS 4John A. Burns School of Medicine

Oct. 4, 2015

Bag mask ventilation

• In non-emergency situations, provides adequate ventilation and oxygenation to give the clinician time to pursue a controlled and well-planned approach to definitive airway management, such as endotracheal intubation

Preoxygenation

• 100% oxygen before induction of anesthesia is standard practice

• Delays onset of arterial hypoxemia during apnea (time to desaturation)

Depends on three things

• Patent airway– Use airway maneuvers and adjuncts

• Adequate mask seal• Proper ventilation

1. Patent airway

• Head tilt, chin lift• Jaw thrust maneuver• Oropharyngeal airway• Nasopharyngeal airway

2. Mask placement

• Cover:– Bridge of the nose– 2 malar eminences– Mandibular alveolar ridge

• Single-handed• Two handed• Problems with seal - troubleshooting

– Facial hair – may need KY jelly or removal– False teeth reinsertion or cheeks expanded with gauze– Lower lip placement, lower end of mask positioned between lower

lip and alveolar ridge reduce median air leak by 95%– Improper mask size

3. Proper ventilation

• Tidal volume– 8-10cc/kg– Excess TV might increase pressure open

gasroesophageal sphincter risk of aspiration• Respiratory rate 10-12• Squeeze bag steadily over one full second– Do not squeeze explosively

• May utilize cricoid pressure

Methods

• 3 mins of tidal breathing• 8 deep breaths within 60s

Other methods…

• 3 breaths in 60s?– Inferior in time for Hb to desaturate to arterial

oxygen saturation (95%)– PaO2 was lower at the end compared to other

methods

Plausible causes

• Differences in oxygen carriage by blood– Respiratory alkalosis induced by 8 breaths in 60s

might increase oxygen carriage by blood • Interaction of preoxygenation methods with

cardiac output

Difficult mask ventilation

• 5% of cases• 2/5 criteria increase risk of difficult intubation

– Age older than 55– BMI > 26– Lack of teeth– Beard– h/o snoring

• Helps predict the risk of difficult airway better management, to decrease morbidity and mortality from failed ventilation

• Next, airway management…

References

• Langeron, O., Masso, E., Huraux, C., Guggiari, M.,Bianchi, A., Coriat, P., Riou, B. (2000). Prediction of Difficult mask ventilation. Anesthesiology, 92: 1229-36.

• Pandit, J. J., Phil, D., Duncan, T., Robbins, P.A. (2003). Total Oxygen Uptake with Two Maximal Breathing Techniques and the Tidal Volume Breathing Technique: A Physiologic Study of Preoxygenation. Anesthesioogy, 99: 841-6.

• Wittels, Kathleen (2015). Basic airway management in adults. Up to date. http://www.uptodate.com/contents/basic-airway-management-in-adults?source=machineLearning&search=mask+ventilation&selectedTitle=1~150&sectionRank=1&anchor=H12#H12

Thank you for your time and attention!