In this statement, five main components of high-performance CPR have been identified: chest compression fraction (CCF), chest compression rate, chest compression depth, chest recoil (residual leaning), and ventilation. These CPR components were identified because of their contribution to blood flow and outcome.
Minimize Interruptions: CCF >80%
For adequate tissue oxygenation, it is essential that healthcare providers minimize interruptions in chest compressions and therefore maximize the amount of time chest compressions generate blood flow. CCF is the proportion of time that chest compressions are performed during a cardiac arrest. The duration of arrest is defined as the time cardiac arrest is first identified until time of first return of sustained circulation. To
maximize perfusion, the 2010 AHA Guidelines for CPR and ECC recommend minimizing pauses in chest compressions. Expert consensus is that a CCF of 80% is achievable in a variety of settings. Data on out-of-hospital cardiac arrest indicate that lower CCF is associated with decreased ROSC and survival to hospital discharge. One method to increase CCF that has improved survival is through reduction in preshock
pause.
Chest Compression Rate of 100 to 120/min
The 2010 AHA Guidelines for CPR and ECC recommend a chest compression rate of ≥100/min. As chest compression rates fall, a significant drop-off in ROSC occurs, and higher rates may reduce coronary blood flow and decrease the percentage of compressions that achieve target depth. Data from the ROC Epistry provide the best evidence of association between compression rate and survival and suggest an optimum target of between 100 and 120 compressions per minute. Consistent rates above or below that range appear to reduce survival to discharge.
.jpg)
Chest Compression Depth of ≥50 mm in Adults and at Least One Third the Anterior-Posterior Dimension of the Chest in Infants and Children Compressions generate critical blood flow and oxygen and energy delivery to the heart and brain. The 2010 AHA Guidelines for CPR and ECC recommend a single minimum depth for compressions of ≥2 inches (50 mm) in adults. Less information is available for children, but it is reasonable to aim for a compression depth of at least one third of the anterior-posterior dimension of the chest in infants and children (≈1½ inches, or 4 cm, in infants and ≈2 inches, or 5 cm, in children).
Although a recent study suggested that a depth of ≥44 mm in adults may be adequate to ensure optimal outcomes, the preponderance of literature suggests that rescuers often do not compress the chest deeply enough despite recommendations. Earlier studies suggested that compressions at a depth >50 mm may improve defibrillation success and ROSC in adults. A recent study examined chest compression depth and survival in out-of-hospital cardiac arrest in adults and concluded that a depth of <38 mm was associated with
a decrease in ROSC and rates of survival. Confusion may result when a range of depths is recommended and training targets differ from operational performance targets. Optimal depth may depend on factors such as patient size, compression rate, and environmental features (such as the presence of a supporting mattress). Outcome studies to date have been limited by the use of mean compression depth of CPR, the impact of the variability of chest compression depth, and the change in chest compliance over time.
Full Chest Recoil: No Residual Leaning
Incomplete chest wall release occurs when the chest compressor does not allow the chest to fully recoil on completion of the compression. This can occur when a rescuer leans over the patient’s chest, impeding full chest expansion. Leaning is known to decrease the blood flow throughout the heart and can decrease venous return and cardiac output. Although data are sparse regarding outcomes related to leaning, animal studies have shown that leaning increases right atrial pressure and decreases cerebral and coronary perfusion pressure, cardiac index, and left ventricular myocardial flow. Human studies show that a majority of rescuers
often lean during CPR and do not allow the chest to recoil fully. Therefore, the expert panel agrees that leaning should be minimized.
Avoid Excessive Ventilation: Rate <12 Breaths per Minute, Minimal Chest Rise
Although oxygen delivery is essential during CPR, the appropriate timeframe for interventions to supplement existing oxygen in the blood is unclear and likely varies with the type of arrest (arrhythmic versus asphyxial). The metabolic demands for oxygen are also substantially reduced in the patient in arrest even during chest compressions. When sudden arrhythmic arrest is present, oxygen content is initially sufficient, and high-quality chest compressions can circulate oxygenated blood throughout the body. Studies in animals and
humans suggest that compressions without ventilations may be adequate early in nonasphyxial arrests. When asphyxia is the cause of the arrest, the combination of assisted ventilation and high-quality chest compressions is critical to ensure sufficient oxygen delivery. Animal and human studies of asphyxial arrests have found improved outcomes when both assisted ventilations and high-quality chest compressions are
delivered.
Providing sufficient oxygen to the blood without impeding perfusion is the goal of assisted ventilation during CPR. Positive-pressure ventilation reduces Coronary Perfusion Pressure (CPP) during CPR, and synchronous ventilation (recommended in the absence of an advanced airway) requires interruptions, which reduces CCF. Excessive ventilation, either by rate or tidal volume, is common in resuscitation environments. Although chest compression−only CPR by bystanders has yielded similar survival outcomes from out-of-hospital arrest as standard CPR, there is presently not enough evidence to define when or if ventilation should be withheld by experienced providers, and more data will be required.
This information has been taken from CPR Quality: Improving Cardiac Resuscitation Outcomes Both Inside and Outside the Hospital: A Consensus Statement From the American Heart Association, published June 25, 2013.
For more information, you can read the journal article here
