When performing 2-rescuer CPR, one person delivers chest compressions while the other provides ventilations (rescue breaths). The compression-to-ventilation ratio for adults is 30:2, the same as single-rescuer CPR, and rescuers should swap roles every 2 minutes to prevent fatigue. The key advantage of having two rescuers is better-quality compressions, fewer interruptions, and the ability to integrate an AED without stopping CPR.
Roles of Each Rescuer
The two roles are compressor and ventilator. The compressor pushes hard and fast on the center of the chest at a rate of 100 to 120 compressions per minute, allowing the chest to fully recoil between each push. The ventilator positions themselves at the victim’s head, maintains an open airway, and delivers 2 breaths after every 30 compressions. Each breath should take less than 1 second and deliver just enough air to make the chest visibly rise.
If a bag-valve mask is available, the ventilator holds the mask to the face with one hand and squeezes the bag with the other during the pause after every 30 compressions. Getting a tight seal with one hand can be difficult. Research published in The Journal of Emergency Medicine found that a two-handed seal on the mask produces a significantly better fit, so if a third person is available, one rescuer can hold the mask with both hands while another squeezes the bag.
When the Second Rescuer Arrives
If CPR is already in progress by one rescuer and a second person shows up, the first priority is confirming that emergency medical services have been called. If they haven’t, the second rescuer calls 911 before doing anything else. If EMS is already on the way, the second rescuer should grab an AED if one is nearby, or step in to begin two-rescuer CPR immediately.
The transition should be seamless. The new arrival takes over one role (typically ventilations) while the original rescuer continues compressions. There’s no need to stop and restart from scratch.
Switching Roles Every 2 Minutes
Chest compressions are physically exhausting, and compression quality drops noticeably after about 2 minutes even when the rescuer doesn’t feel tired. Guidelines recommend switching the compressor and ventilator positions every 2 minutes, which works out to roughly 5 cycles of 30 compressions and 2 breaths.
The switch itself should take less than 5 seconds. Every second without compressions means less blood flow to the brain and heart, so both rescuers need to anticipate the change. A good approach: the compressor counts the fifth cycle out loud, finishes the last compression, and immediately moves to the head while the ventilator slides into the compression position. Practicing this swap beforehand makes a real difference in keeping interruptions short.
Compression-to-Ventilation Ratios
For adults, the ratio is 30 compressions to 2 breaths whether you have one rescuer or two. This ratio stays the same in both scenarios.
For infants and children, the ratio changes when a second rescuer is present. Two rescuers use a 15:2 ratio (15 compressions, then 2 breaths) for pediatric patients, which delivers more frequent ventilations. This matters because cardiac arrest in children is more often caused by breathing problems than by a heart rhythm issue, so ventilation plays a bigger role. A lone rescuer still uses 30:2 for all ages to keep the sequence simple.
Using an AED During 2-Rescuer CPR
Having two rescuers makes AED use far more efficient. One rescuer continues compressions without stopping while the second rescuer turns on the AED, applies the pads, and follows the prompts. Compressions should not be interrupted until the AED is fully powered on and ready to analyze the heart rhythm.
Once the AED begins its analysis, both rescuers must stop touching the victim. A practical technique is to hover with hands a few inches above the chest so you can resume compressions the instant the AED delivers a shock or advises that no shock is needed. Compressions restart immediately after the shock, not after another pulse check.
The AED analysis also provides a natural moment to swap roles. Each time the AED cycles through an analysis (roughly every 2 minutes), the rescuers should trade positions so the compressor stays fresh.
When an Advanced Airway Is Placed
If emergency responders insert an advanced airway (such as a breathing tube), the coordination between compressions and breaths changes significantly. Instead of pausing compressions every 30 pushes for 2 breaths, the compressor now pushes continuously without stopping, and the ventilator delivers 1 breath every 6 seconds (10 breaths per minute) independent of the compression cycle. This continuous compression approach maximizes blood flow because there are no longer pauses built into each cycle.
Checking for a Pulse
Before starting CPR, rescuers check for breathing and a pulse simultaneously. This check should take at least 5 seconds but no more than 10. If there’s no pulse or you’re not sure, start compressions immediately. During CPR, pulse checks happen every 2 minutes when you pause to switch roles. Don’t extend the pause beyond what’s needed for the swap, and keep your hands close to the chest so you can restart without delay if there’s still no pulse.
Putting It All Together
The full sequence for 2-rescuer adult CPR looks like this:
- Confirm safety and responsiveness. Check for breathing and a pulse for 5 to 10 seconds.
- Assign roles. One rescuer begins 30 compressions at 100 to 120 per minute. The other manages the airway and prepares to ventilate.
- Deliver 2 breaths after every 30 compressions, each under 1 second, watching for chest rise.
- Switch roles every 2 minutes (after 5 cycles of 30:2), keeping the interruption under 5 seconds.
- Apply the AED as soon as one is available, without pausing compressions until it’s ready to analyze.
- Continue until EMS takes over, the person starts breathing and has a pulse, or you physically cannot continue.
The entire point of two-rescuer CPR is minimizing gaps in chest compressions. Every element of the protocol, from the quick role switch to the AED timing to keeping your hands hovering during analysis, exists to keep blood moving. The better you coordinate with your partner, the more effective each compression becomes.