Improving the Quality of Chest Compressions in Cardiopulmonary Resuscitation

Cardiac arrest calls for an emergency first aid procedure known as Cardiopulmonary resuscitation (CPR).

Cardiopulmonary resuscitation works by restarting the natural process of blood transport in the circulatory system. This allows for oxygenated blood to reach essential organ systems.

CPR first aid employs the use of chest compressions as well as mouth to nose/mouth assisted breathing.

Past studies have agreed that the quality of these chest compressions matter particularly as regards to the number of compressions per minute (or rate) and how deep these chest compressions should go.

In light of these past studies, the University of Minnesota embarked on a study titled Optimal Combination of Compression Rate and Depth During Cardiopulmonary Resuscitation for Functionally Favorable Survival.

The study intended to find ways to determine the best depth-rate combination that could improve the effectiveness of chest compression CPR in outside-hospital patient survival and recovery.

We trace back related studies and efforts to improve the rate-depth quality of chest compression CPR to see the significance of this new study by the University of Minnesota Medical School.

But first, let’s understand what cardiac arrest is and how chest compressions in CPR can help its victims.

What is Cardiac Arrest?

Sudden cardiac arrest is the medical term that defines the stopping of the heart’s normal activity of transporting blood to all areas of the body. When a remedy is not applied quickly, death may occur within a short time.

Cardiac arrest can happen suddenly or after certain medical manifestations. It must be detected quickly. When it occurs, the victim may survive with minimal or no organ and tissue injury.

Cardiac arrest can happen due to a chain of certain influences. The principal origins of the ailment include atrial fibrillation and ventricular fibrillation.

Atrial fibrillation is where the atria is deprived of regular flow action. An irregular heartbeat occurs when the sinoatrial node is unable to produce the electrical signal to initiate heart contractions.

Ventricular fibrillation is when the two lower chambers are derived from normal flow action. This deteriorates the blood supply mechanism of the heart. Blood transfer to vital organ systems is affected and, in certain instances, it may halt completely.

Between the two causes, ventricular fibrillation is the leading cause of most incidents of cardiac arrest. Since it is characterized by a quivering violent movement of the ventricles, blood transport occurs insufficiently.

In the US alone, about 370,000 incidents occur within a year. These cases often occur away from a medical center or hospital. This means that many people may suffer an arrest when they are just going on with normal activities such as working, sleeping, or traveling.

What are Chest Compressions in CPR?

Cardiopulmonary Resuscitation is a form of emergency first aid for cardiac arrest victims. It is applied to a person who is unresponsive and has agonal breathing. This form of respiration is not correct breathing since it does not supply enough oxygen to vital organs such as the brain.

When it comes to giving CPR, time is a crucial factor. It should begin as soon as possible until the paramedics arrive or the victim regains consciousness.  Seconds can determine if a person will survive or not.

Cardiopulmonary resuscitation works by restarting the natural process of blood transport in the circulatory system. This allows for oxygenated blood to reach essential organ systems.

CPR first aid employs the use of chest compressions as well as mouth to nose/mouth assisted breathing.

Compressions help to restart the action of blood circulation. This is applied with the victim laying on their back.

Next, the lifesaver should interlock their fingers and press on the sternum area up almost two inches inside. The pressure is then released to allow the chest to rise. The compressions should go on uninterrupted and include almost a hundred pushes per minute.

How Deep and How Fast We Conduct CPR Chest Compressions Impacts Cardiac Arrest Survival

The number of compressions per minute and the depth at which a lifesaver administers chest compressions determines whether they save and revive a cardiac arrest victim; these were according to the findings of a 2015 study by a UT Southwestern Emergency Medicine Medical.

The report contradicted a popular practice when it indicated that chest compressions deeper than 5.5 centimeters reduced the chances of survival, probably because going that deep caused harm to other body organs.

Earlier, studies and instructions insisted that deeper chest pushes were more effective. Back in 2010, the AHA’s 2010 Cardiopulmonary Resuscitation instructions suggested pushing the chest about 5 centimeters deep but gave no top figure.

According to Professor Ahamed Idris of UT Southwestern, it takes a lot of pressure to go 5 centimeters deep that chances are high a lifesaver could harm a victims internal organs.

 “Many people do not consider that one must use a significant amount of force to push the chest down 5 cm deep. We are talking around 60 lbs. of pressure, and this could go up depending on the surrounding or knowledge of the bystander.”

The researchers also sought to investigate the optimal number of compressions per minute (or rate) to ensure survival.

And after considering all other aspects, they found 100 to 120 compressions per minute as the optimal rate for survival.

UT Southwestern also found that nearly 50 percent of candidates were issuing chest compressions faster than expected, 1/3 of this group exceeded 120 pushes per minute, and 1/5 went above 140 pushes per minute.

In the end these two separate studies concluded that;

Whether a cardiac arrest victim survives depends on the on the quality of the Cardiopulmonary Resuscitation issued. These two factors; (1) the number of compressions per minute and (2) the depth of compressions, are excellent ways to improve the quality of CPR and increase cardiac arrest survival rates.

It is also from the above studies and other related investigations that that the University of Minnesota developed their new CPR method. Find out everything you need to know about it.

A Look into University of Minnesota’s New and Improved CPR

Recently, the University of Minnesota embarked on a study titled Optimal Combination of Compression Rate and Depth during Cardiopulmonary Resuscitation for Functionally Favorable Survival.

The study intended to find ways to see if better chest compressions could improve the effectiveness of CPR.
Here’s an overview of the study according to JAMA Cardiology;

  • Significance: PastCPR studies have indicated thatthe number of compressions per minute (or rate) and the depth of chest compression are both linked to the chances of survival of outside-hospital cardiac arrest. But the ideal number of compressions per minute and the depth of the pushes are yet to be determined, more so as regards to factors like sex, age, sex, heart rhythm, and CPR device use.
  • Goal: To determine the best possible rate-depth combination linked to the best survival rates and to analyze whether the finding varies as regards to age, sex, heart rhythm, or CPR gadget use.
  • Design, Setting, and Respondents: The group study relied on data gathered from Jun. 2007 to Nov. 2009 during a National Institutes of Health clinical tests registry of outside-hospital and in-patient emergency care provided by EMS systems operating in the US and Canada.

The sample size was 3640 victims of outside-hospital cardiac arrest and for whom rate and depth compressions had been concurrently recorded during the National Institutes of Health clinical tests of an airway-opening CPR gadget.

Sub-cohort studies looked into variations such as age, sex, heart rhythm, and use of a CPR device. The data was analyzed between Sept. and Nov. 2018.

  • Outcomes: The best possible rate-depth combination linked to higher survival chances in general and by sex, age, cardiac rhythm, and CPR device use.
  • Results and significance: The results recommend compressions 4.7 cm deep and up to 107 chest compressions per minute linking the combination to considerably increased outside-hospital cardiac arrest outcomes. The findings call for further studies and proof.

The University of Minnesota’s study investigated150 US and Canadian EMS agencies. The studied focused on over 3600 outside-hospital cardiac arrest victims.

Chest compression rate for CPR was being recorded as part of a clinical test conducted by the National Institute of Health’s Resuscitation Outcomes Consortium, with a cardiopulmonary resuscitation gadget known as the impedance threshold device (ITD).

This study is also unique and significant because it is the first test that involved electronically documented results from multiple centers showing the number of compressions per minute and the depth of compression.

The study found that the best outcomes are experienced when CPR starts and continues for 5 minutes at around 107 compressions per minute and goes around 4.7 cm deep.

This optimal combination stays the same for victims of all ages, sexes, regardless of the heart rhythm and whether or not any CPR gadget that opens the airway was used.

Using a device did not offer any better survival advantages as long as the depth-rate combination remained ideal.

The researchers ruled the outcome by checking the revival of the neurological function after a CPR-rescued cardiac arrest.

Another noteworthy finding was that administering cardiopulmonary resuscitation at 80 to 100 percent of this optimal combination led to a 6 percent survival rate with undamaged brain function, compared to 4 percent if the ideal combination wasn’t followed.

While the range does not look quite significant; it could mean rescuing thousands of cardiac arrest victims if implemented considering the 300 000 outside-hospital cases. This is enough motivation to prompt the acceptance of this new CPR method worldwide.

This study is an improvement fromprevious investigations that sought to find the best rate-depth combination.

Most of the studies agreed that the ideal chest compressions lies somewhere between100 to 120 pushes per minute could better survival rates and reduce the risk of brain damage. Every attempt has come up with their optimal ranges for better results.

But depth is also a concern when it comes to giving chest compressions. The study team referred to previous research on the depth and compressions/minute in male, females, individuals of different ages, and victims who waited longer for cardiopulmonary resuscitation after a sudden cardiac arrest.

The University of Minnesota’s research team considered the above factors before coming up with this new CPR method.

Paul Pepe, one of the research experts referred to the findings as “critical new knowledge” that does not only stress the significance of best CPR practices but may also lead to the rescue of more victims.

The research relied on CPR data carried out on over 3640 people who suffered outside-hospital cardiac arrest with a CPR gadget known as impedance threshold device (ITD) that minimizes chest pressure and increases the return of the blood in the veins to the heart.

The respondents were trained to use the gadget using sophisticated airway techniques or a face mask while issuing chest compression and ventilation per the AHA’s instructions.

These included around 80-100 compressions every minute, a 4 to 6 centimeter depth and 10 pressure-breaths every minute, to attain around about 600 mL tidal volume.

These results may now need to be proven by further research. What’s more, the studies should involve other Emergency medical services in areas other than the US and Canada to ascertain its worldwide validity.

Limitations of the University of Minnesota’s study

The results of the UoM’s research team may not apply globally. There’s the need to conduct more studies to prove and modify these findings because some factors may change moving forward.

It also included Emergency Medical Services Systems with seemingly veteran 911 agencies and monitored outside-hospital cardiac arrest cases registered with the NIH Resuscitation Outcome Consortium executive and therefore may not represent other cases.

But even if the findings only applied to a group of EMS service providers that are well trained in rescuing operations and are keen quality CPR, these factors should only better the outcome and not dispute the validity of these results.

Again, CPR was not always issued optimally. Focusing on rescuers with instructions to issue compressions at the, 80-100 compressions/minute and a depth of 4-6 centimeters may as well be termed as selection partiality.

But past studies have alsoindicated that even with optimal rate of compressions, the depth of the chest pushes may not be accurate or the reverse.

The study also sought to investigate the best possible rate-depth combination and find out whether the target changed by age, sex, heart rhythm, or the use of an airway-opening device.

Over 50 percent of the patients were found to be in the rate-depth grids beyond a worked-out ideal target combination range of 20 percent, and an entire 80 percent of the participants did not appear in the four most occupied survivor grids.

Furthermore, many patients in general received rate-depth combinations way below what was defined by this study to be the optimal grid survivor areas.

The study group also featured victims who had synchronized recordings of rate and depth taken. This group was taken from a larger group of candidates picked from clinical tests. Many times (almost 57 percent of the times) the rates and depths weren’t measured at the same time within the stipulated 5-minute span or were not obtainable due to technical issues.

And while this may also raise concerns of possible selection partiality, the new study group was a representation of the full group when put side by side with the area-specific and clinical results of the initial clinical trial group.

Another downside to the UoM’s study was that it ignored or failed to consider the quality of recoil of the chest wall and it gathered no data (such as tidal volume, timing, frequency and more) concerning the real function of the assisted ventilation.

Yet past studies have shown that all these pieces of data can impact the general outcomes and the ideal rate-depth combination mentioned in this research could change if the it included data related to wall recoil, compression fraction, ventilatory parameters, as well as any other factors.

However, if we consider that that the current study group was well chosen, we can as well make a reasonable assumption that the recoil and ventilatory factors were optimal and further improvement of these two would probably better the chances of survival chances even further when administering an optimal rate-depth combination.

Nevertheless, the researchers left these factors as focus metrics to collect and analyze to ensure the best CPR practices and increase survival chances among cardiac arrest victims.

Measurement & Feedback is Critical in Achieving High-Quality Cardiopulmonary Resuscitation

So what next for the future of CPR?

It is popular belief that survival rates of outside-hospital cardiac arrest have remained low despite the popularity of emergency medical service (EMS) systems around the globe.

But that is not true according to findings from recent studies by bodies like the NIH’s Resuscitation Outcomes Consortium and many other local studies in the US as well as other countries.

The truth is; survival from outside-hospital CPR has increased significantly.

So, what are the similarities in the areas that record increased outside-hospital CPR survival rates? And what are some of the areas we can improve on—based on previous results— to rescue more victims?

A major similarity in zones that record better survival rates is that all of them insist on best CPR practices to ensure the best-quality cardiopulmonary resuscitation in outside-hospital victims by measuring what they are doing and making improvements.

The number of compressions per minute (or rate),  depth of compression, shock-pause duration, release velocity and the obtaining CPR feedback are all linked to better results and appear as focus points in may recent studies .

Regrettably, many rescue teams and bystander training institutions do not utilize these metrics to improve their CPR even with an array of tech that makes the task hassle-free and affordable.

Instead, many systems look for excuses such as lack of capital or finances and lack of resources to measure these determinants of optimal CPR.

We can’t track progress and make improvements if we don’t measure performance. It is important that every EMS system measures the effectiveness of its CPR procedures and seek constructive feedback to use in future improvements.

Quality guarantee programs must be viewed as useful tools and not a liability. Most EMS systems forget to plan for quality improvement which is why they view it as an extra unwanted cost and task.

The future of cardiac arrest study is full of new ideas and exploration into new policies focused on refining outside-hospital cardiac arrest survival but none of them will be useful without quality assessment and improvement.

Without measurement and quality improvement, even the best of ideas will not realize the best outcomes. So let’s all lay emphasis on refining the quality of the cardiopulmonary resuscitation we give all over the world.


The seriousness of chest compressions and the frequency at which they were exerted make a significant impact on the recovery and survival of a cardiac arrest victim.

The study by the University of Minnesota marks a significant change in the way CPR process but that doesn’t mean we cannot do further measurements to save more lives.

Quality assessment and improvement should be a continuous process. In fact, any resuscitation group should have a development plan in mind from the start.

Improving the quality of CPR is the best way to change the notion that outside-hospital CPR is ineffective in saving lives.

All resuscitation bodies have a joint responsibility to improve the effectiveness of cardiopulmonary resuscitation.