Duration of Each CPR Cycle
Each CPR cycle should be performed for 2 minutes before pausing to reassess rhythm or check for return of spontaneous circulation. 1
Standard CPR Cycle Duration
CPR should be performed continuously for 2 minutes (approximately 5 cycles of 30 compressions and 2 breaths) before any interruption for rhythm assessment. 1
After delivering a shock with an AED/defibrillator, resume CPR immediately for 2 minutes before the next rhythm check. 1
For non-shockable rhythms, continue CPR for 2 minutes before reassessing. 1
Compression-to-Ventilation Ratios Within Each Cycle
The ratio varies by patient age and number of rescuers:
Adults
- Single rescuer or multiple rescuers: 30 compressions to 2 breaths 1
- With an advanced airway in place: continuous compressions at 100-120/minute with 1 breath every 6 seconds (10 breaths/minute) 1, 2
Pediatrics (Healthcare Providers)
- Single rescuer: 30 compressions to 2 breaths 1
- Two or more rescuers: 15 compressions to 2 breaths 1
- With an advanced airway: continuous compressions with 1 breath every 2-3 seconds (20-30 breaths/minute) 1
Key Quality Metrics During the 2-Minute Cycle
- Compression rate: 100-120 per minute 1
- Compression depth: At least 2 inches (5 cm) in adults; at least one-third anteroposterior diameter in children 1
- Allow complete chest recoil between compressions 1
- Minimize interruptions in compressions 1
Rescuer Rotation
- Change the compressor every 2 minutes (or sooner if fatigued) to maintain compression quality. 1
- Rescuer fatigue can lead to inadequate compression depth and rate, with significant fatigue occurring after just 1 minute of CPR, though rescuers may not recognize it for 5 minutes. 1
Practical Considerations
- The 2-minute interval corresponds to approximately 5 cycles of CPR at a 30:2 ratio (each cycle = 30 compressions + 2 breaths). 1
- Research shows that counting 5 cycles is easier for newly trained providers than estimating 2 minutes, with 77.5% of participants finding cycle counting preferable. 3
- The average time to complete 5 cycles of CPR is approximately 115 seconds (just under 2 minutes). 3
Common Pitfalls to Avoid
- Do not interrupt compressions to check for pulse or ROSC during the 2-minute cycle unless the patient shows obvious signs of movement or recovery. 1
- Limit interruptions to no longer than 10 seconds for specific interventions like defibrillation or advanced airway placement. 1
- Avoid excessive ventilation, which increases intrathoracic pressure and decreases cardiac output. 1, 2
- Do not delay compressions to set up airway equipment—compressions take priority (CAB sequence). 1