Bag-Mask Ventilation After Induction and Paralysis
The PREOXI trial does not directly address bag-mask ventilation after induction and paralysis; however, current pre-hospital anesthesia guidelines recommend that if a patient becomes hypoxaemic during intubation attempts, the lungs should be ventilated via a facemask or supraglottic device. 1
Context: The PREOXI Trial Is Not Included in This Evidence
The evidence provided does not contain the PREOXI trial. The question cannot be answered based on what the PREOXI trial specifically recommends. However, I can provide guidance on bag-mask ventilation after induction based on the available high-quality guidelines.
Current Guideline Recommendations on Post-Induction Ventilation
When Bag-Mask Ventilation Is Indicated
If hypoxaemia develops during intubation attempts, immediate bag-mask ventilation or supraglottic airway ventilation is recommended to restore oxygenation before the next attempt. 1
The number of intubation attempts should be limited to three, and between attempts, conditions should be optimized—this includes ventilating the patient if oxygen saturation drops. 1
Pre-Oxygenation Phase (Before Paralysis)
Hypoxaemic patients (SpO₂ <90%) or those with poor respiratory effort require gentle bag-mask ventilation support during pre-oxygenation to facilitate adequate oxygenation before induction. 1
Ventilation pressures should be kept below 25 cmH₂O during pre-oxygenation to reduce the risk of gastric distension and subsequent aspiration. 1
Apnoeic Oxygenation Strategy
Apnoeic oxygenation via nasal cannulae may prolong time to desaturation when the airway remains patent, though the evidence base is limited. 1
This technique has been shown to decrease desaturation incidence in pre-hospital emergency anesthesia settings. 1
Critical Considerations During Bag-Mask Ventilation
Cricoid Pressure Management
Cricoid pressure should be applied during induction to reduce aspiration risk, but it may make bag-mask ventilation difficult. 1
There should be a low threshold for removing cricoid pressure if it impairs ventilation or laryngoscopy view. 1
Positioning for Optimal Ventilation
Head-elevated positioning (30-45 degrees or reverse Trendelenburg if spinal injury suspected) improves oxygenation and reduces aspiration risk during the peri-induction period. 1
For obese patients, ramped positioning is essential to maintain airway patency and facilitate both bag-mask ventilation and intubation. 1
Post-Intubation Ventilation Strategy
Avoid Zero PEEP
After successful intubation, lung-protective ventilation with PEEP of at least 5 cmH₂O should be initiated immediately—zero PEEP is not recommended. 1, 2
Transport ventilators are preferred over continued hand ventilation to decrease hyperventilation risk and free up team members. 1
Avoid Bag-Squeezing Recruitment Maneuvers
- If recruitment maneuvers are performed, bag-squeezing techniques should be avoided in favor of ventilator-driven maneuvers with controlled plateau pressures (30-40 cmH₂O in non-obese, 40-50 cmH₂O in obese patients). 1
Common Pitfalls to Avoid
Do not withhold bag-mask ventilation in a desaturating patient out of fear of gastric insufflation—hypoxaemia is more immediately life-threatening than aspiration risk, but keep pressures <25 cmH₂O when possible. 1
Do not continue multiple intubation attempts without intervening ventilation—this leads to progressive hypoxaemia and cardiovascular collapse. 1
Do not maintain cricoid pressure if it prevents effective bag-mask ventilation—oxygenation takes priority. 1
Avoid apnoea with zero PEEP before or after extubation—this promotes rapid atelectasis formation. 1