How can a healthcare provider optimize ventilation efficiency during cardiac arrest?

Optimizing Ventilation Efficiency During Cardiac Arrest

Healthcare providers should deliver ventilations at a rate of 10 breaths per minute (1 breath every 6 seconds) with tidal volumes of 500-600 mL, avoiding excessive ventilation which impairs venous return and reduces survival. 1

Key Ventilation Parameters

Respiratory Rate

• Deliver 1 breath every 6 seconds (10 breaths/minute) when an advanced airway is in place during continuous chest compressions 1, 2
• Before advanced airway placement, use 30:2 compression-to-ventilation ratio with 2 breaths delivered during pauses in compressions 1
• Each breath should be delivered over 1 second 1

Tidal Volume

• Target 500-600 mL (6-7 mL/kg) tidal volumes - this is sufficient to produce visible chest rise while maintaining oxygenation 1
• Use an adult bag (1-2 L) and compress approximately two-thirds of a 1-L bag or one-third of a 2-L bag 1
• Deliver only enough volume to make the chest rise visibly - no more 1

Critical Pitfall: Hyperventilation

Excessive ventilation is extremely common and directly harmful - studies show providers routinely deliver 20-40 breaths per minute instead of the recommended 10, which is associated with worse outcomes 3, 2

Why Hyperventilation Kills

• Increases intrathoracic pressure, impeding venous return 1, 3
• Reduces cardiac output and coronary perfusion pressure 1, 3
• Decreases cerebral blood flow 1
• Causes air trapping and barotrauma 1
• Increases gastric inflation, regurgitation, and aspiration risk 1

How to Avoid Hyperventilation

• Use a metronome or timer to maintain exactly 10 breaths per minute 2
• Assign one team member to monitor and call out ventilation rate 3
• If using mechanical ventilation during CPR, disconnect the ventilator and switch to manual ventilation - modern ventilators erroneously sense chest compressions as spontaneous breaths and deliver excessive rates 4

Airway Management Options

Bag-Mask Ventilation

• Bag-mask ventilation is acceptable and may be safer than advanced airways for short transport times, particularly when providers lack extensive intubation experience 1
• Requires proper technique: correct mask size, tight seal, jaw thrust, and visible chest rise 1
• Two-person technique is preferable when personnel available - one maintains seal and airway, other compresses bag 1

Advanced Airways

• Either supraglottic airway (SGA) or endotracheal tube (ETT) may be used as initial advanced airway 1
• Key advantage: allows continuous chest compressions without pauses for ventilation 1
• Must be placed by providers with adequate training and ongoing experience 1
• Confirm placement with continuous waveform capnography 1, 5

Supraglottic Airways (Laryngeal Tube, LMA)

• Faster to insert than ETT - enables ventilation more rapidly with less interruption to compressions 6, 7
• Success rates of 85% when used by paramedics as sole technique 7
• Provides equivalent minute ventilation to ETT and superior to bag-mask in inexperienced hands 6
• Acceptable alternative when bag-mask fails or ETT not possible 1

Oxygen Delivery

• Use 100% oxygen during CPR - insufficient evidence exists to recommend lower concentrations during arrest 1
• Minimum flow rate of 10-12 L/min through bag-mask device 1
• Attach oxygen reservoir to self-inflating bag to achieve 60-95% delivered oxygen concentration 1

Monitoring Ventilation Quality

Capnography

• PETCO₂ of 35-40 mmHg indicates adequate CPR quality 5, 8
• Abrupt sustained increase in PETCO₂ (typically >40 mmHg) suggests return of spontaneous circulation 5
• Use continuous waveform capnography to confirm advanced airway placement and monitor ventilation 1, 5

Clinical Assessment

• Observe for visible chest rise with each breath 1
• Monitor for gastric distension suggesting excessive ventilation or poor technique 1
• Assess bilateral breath sounds if advanced airway placed 1

Technique-Specific Recommendations

Without Advanced Airway

• Deliver 2 breaths during 5-second pause after every 30 compressions 1
• Each breath over 1 second until chest rises 1
• Minimize interruptions in compressions - end CPR cycles with compressions when possible 1

With Advanced Airway

• Continuous chest compressions at 100-120/minute without pauses 1, 8
• Asynchronous ventilation at 10 breaths/minute 1, 2
• No coordination needed between compressions and breaths 1

Special Considerations

Cricoid Pressure

• Do not use routine cricoid pressure - it may impede ventilation and delay advanced airway placement without preventing aspiration 1
• May be considered only to aid visualization during intubation 1

Manual vs. Mechanical Ventilation

• Disconnect mechanical ventilators during CPR - they deliver excessive rates by sensing compressions as spontaneous breaths 4
• Use manual self-inflating bags or volume-marked resuscitation devices that can be synchronized with compressions 4