Comparing Manual and Mechanical Chest Compressions

Cardiac arrest is an important public health issue. More than 326,000 people experience nontraumatic, out-of-hospital cardiac arrest in the United States, and it is the leading cause of death for adults ages 40 and older. Although we have made advances over the years in treating cardiac arrest with more efficient cardiopulmonary resuscitation (CPR), quick defibrillation, advanced cardiac life support (ACLS) techniques, and therapeutic hypothermia, only one in 10 will survive an out-of-hospital cardiac arrest.1

With more than 85 million people in the United States living with cardiovascular disease or the after-effects of stroke, the treatment of cardiac arrest patients will continue to challenge emergency medical services (EMS).2 It is our responsibility to offer the highest standard of care to achieve the best possible outcome for our patients. Quality CPR provided as close to cardiac arrest as possible is the most important component of our treatment.

In 2010, the American Heart Association (AHA) released new guidelines stressing the importance of continuous, high-quality chest compressions to generate blood flow and oxygen delivery to the myocardium and brain without delay.3 A recently published paper found that the quality of chest compressions directly relates to patient outcome. It was found that when “rescuers compress at a depth less than 33mm [millimeters], survival-to-discharge rates after out-of-hospital arrest are reduced by 30 percent.” When compressions are too slow, return of spontaneous circulation (ROSC) fell from 72 percent to 42 percent.4

It was also found that 75 percent of all cardiac arrests result from nonshockable rhythms, making the more intense, higher-quality CPR even more important than before. It was estimated that approximately 2,500 more lives could be saved in the United States by following these 2010 recommendations.5

Quality of Chest Compressions

How do we in EMS ensure that our chest compressions are of the highest quality? First and foremost, we follow the AHA guidelines. Every two years, first responders are required to have a refresher course in CPR and ACLS. We learn about the latest updates and make adjustments in the way we treat cardiac arrest patients.

The 2015 recommendations put a strong emphasis on high-quality chest compressions at a rate of 100 per minute and no more than 120. Studies have found that the higher the rate of compression, the greater the instance of inadequate depth. When rates were between 120 and 139 per minute, inadequate depth rate occurred 50 percent of the time. When rates were above 140, inadequate depth rate was observed 70 percent of the time.6

The AHA recommends a compression depth of two inches and also avoiding excessive depths (greater than 2.4 inches). A small study revealed that compressions that are too deep may result in nonlife-threatening injuries; however, more often than not, our compressions are too shallow. (6)

(1) LUCAS 2 in use on a patient. <i>(Photo courtesy of Physio-Control Corporation.)</i>
(1) LUCAS 2 in use on a patient. (Photo courtesy of Physio-Control Corporation.)

Another point that the AHA stresses in its 2015 guidelines is the importance of chest recoil. If the sternum is not allowed to return to its neutral or natural position, the intrathoracic pressure needed for venous return will not be negative and chest compressions will be inadequate. When rescuers are fatigued, they may not realize that they are leaning on the chest and not allowing the chest recoil to take place, which also prevents the heart from filling completely. (6)

Finally, the AHA reminds us, in 2010 and again in 2015, to attempt to minimize interruptions in chest compressions. It recommends that rescuers provide chest compressions for at least 60 percent of the entire time they are with the patient and to cease compressions only for required care like rhythm analysis and ventilation. (6)

If we, as first responders, are not aware of every important aspect of the quality of our chest compressions, it may unwittingly have a negative effect on the patient’s outcome.

Options for Providing Chest Compressions

In the prehospital setting, we have a few options regarding the manner in which we provide chest compressions. The most obvious choice is manual chest compressions by a first responder. Manually providing chest compressions is the least costly option; there are no costs associated with purchasing equipment and training on it. All rescuers are trained every two years to perform chest compressions, and it is a skill that is used on a fairly regular basis in most departments.

Fatigue is the greatest drawback to using a rescuer to perform chest compressions. A study done in 2009 that involved observing in-hospital CPR found that the rate at which the rescuer performed compressions was not affected by fatigue but that the depth of compressions was affected after just 90 seconds of compressions and further decayed to an unacceptable level after three minutes. Because of these findings, it is recommended that rescuers rotate frequently during CPR.7

Another drawback to using a first responder to perform chest compressions is limited personnel. Many departments are still understaffed. Using a first responder to perform chest compressions takes someone away from other necessary actions like defibrillation, establishing an airway, obtaining venous access, and other lifesaving measures.

(2) The AutoPulse. <i>(Photo courtesy of Zoll Medical Corporation.)</i>
(2) The AutoPulse. (Photo courtesy of Zoll Medical Corporation.)

Interruptions in chest compressions are also a drawback that affects coronary perfusion. Many factors contribute to this problem. One factor is the distraction of the rescuer performing chest compressions. Distractions could range from assisting other rescuers with tasks or attempting to control a chaotic scene.

Other interruptions may happen while transporting a patient down the stairs, loading and unloading the patient from the rescue, or any other time when a rescuer cannot place his hands directly on the patient’s chest to perform compressions.

Performing manual chest compressions in the back of a rescue also has its risks. A first responder must remain standing and unrestrained to perform chest compressions. Since traveling with lights and sirens increases the risk of a crash, standing unrestrained is a critical risk factor. Back injuries constitute another risk that first responders face in conjunction with chest compressions. A cramped and mobile environment has been documented as the primary cause of back injuries during CPR.8

Equipment for Chest Compressions

To address these issues, several companies have developed equipment to assist first responders with chest compressions (Table 1).

LUCAS™2

The LUCAS™ Chest Compression System, distributed by Physio-Control, and the AutoPulse, developed by Zoll, are two chest compression devices used by many departments across the country.

LUCAS was introduced in the United States in the summer of 2007. The most recent version, the LUCAS 2, was introduced globally in 2009. The device meets AHA guidelines for rate and depth of compressions and allows for complete recoil of the chest wall after each compression while providing continuous compressions.9

The LUCAS 2 weighs slightly more than 17 pounds and is 22.4 inches in height × 20.5 inches in width × 9.4 inches in depth when assembled and 25.6 inches in height × 13 inches in width × 9.8 inches in depth when inside the backpack. The device is powered by a rechargeable lithium-ion polymer battery. The average battery run time is 45 minutes. Although the device does not have a weight restriction, the sternum height must be between 6.7 inches and 11.9 inches and no wider than 17.7 inches.10

The LUCAS 2 consists of a back plate, which is placed under the patient to support compressions, an upper part with a battery, a compression mechanism, straps to secure the patient’s hands, a disposable suction cup, and a stabilizing strap to secure the position of the device. The upper part is snapped into the back plate. If the back plate does not connect to the upper part, the patient is too large, and the device cannot be used. The suction cup is set on the sternum at the same location where the hands would be placed during manual compressions. The device will audibly alert the first responder if the patient is too small for the device after the suction cup is lowered to the body. (10)

A few drawbacks to the LUCAS 2 are that electrodes, wires, and defibrillator pads must be placed out of the way of the suction cup. If they happen to end up under the suction cup when positioning the device, the electrodes/pads must be replaced with new ones out of the way of the suction cup. The patient’s head is not supported by the back plate; a first responder must support the head while moving the patient. Physio-Control suggests that the device be paused when lifting the patient onto the backboard or stretcher. (10)

Physio-Control advertises that the LUCAS 2 can be applied quickly with an interruption in CPR of “less than 20 seconds.”(9) According to a pilot study, it took two minutes to apply the device.11 A more recent study has shown that, with practice, application times can be shortened to seven seconds.12

It has been proven that the LUCAS 2 shows improved organ perfusion pressures, enhanced cerebral blood flow, and higher end-tidal CO2 compared to manual CPR. But, the end result is that there was no significant difference in the survival of patients treated with the LUCAS 2 vs. manual CPR. 13

AutoPulse

The AutoPulse, introduced by Zoll in 2003, comes with a load-distributing LifeBand attached to the platform and wraps around a wider area of the chest, spreading out the force of compressions. The LifeBand consists of a cover plate and two bands integrated with a compression pad and a hook-and-loop fastener. Once the patient’s armpits are lined up with the alignment reference, the LifeBand is closed and secured around the patient. The device automatically adjusts the LifeBand to the patient and has a weight limit of 300 pounds. It supports the head and has a compression rate of approximately 80 compressions per minute.14

The AutoPulse is battery powered and can weigh up to 25.5 pounds, depending on the battery used. (Li-Ion and NiMH are available; both last for 30 minutes.) The Li-Ion battery takes 4.5 hours to charge; the NiMH battery takes 6.25 hours to charge. The device measures 32.5 inches in length × 17.6 inches in width × 3 inches in height. (11)

A couple of drawbacks to the AutoPulse are that it is not recommended for use on patients with traumatic injuries and its larger size, which makes it heavier and more cumbersome to carry than the LUCAS. (11)

My research has shown that these devices have shown no real difference in patient outcomes than manual chest compressions. There is not yet sufficient data to support or refute the benefits of using them.15

Other Advantages of Mechanical Compression Devices

The 2015 AHA guidelines state there is not enough evidence to support that mechanical chest compressions are more beneficial. However, they also state that when high-quality compressions become challenging in certain settings (limited personnel, prolonged CPR, or in a moving ambulance), a mechanical device may be a reasonable alternative. (6)

Another benefit to using either device is that defibrillation can be performed during compressions, which is not the case with manual compressions.

Loading, unloading, and transferring the patient to the hospital gurney also interrupt chest compressions when performed manually. It may be advantageous to use one of the mechanical devices to eliminate these interruptions.

When deciding on whether or not to implement mechanical compression devices, departments must evaluate their staffing levels, transport times, and budgets. They need to be able to forecast to the best of their abilities if using a mechanical device would improve the outcomes of their cardiac arrest patients.

Endnotes

1. Sudden Cardiac Arrest: A Healthcare Crisis. Sudden Cardiac Arrest Foundation. Retrieved on September 25, 2015. http://www.sca-aware.org/about-sca.

2. American Heart Association. Heart Disease and Stroke Statistics- At-a-Glance. December 17, 2014. http://www.heart.org/idc/groups/ahamah-public/@wcm/@sop/@smd/documents/downloadable/ucm_470704.pdf.

3. Travers, Andrew H, Thomas D Rea, Bentley J Brobrow, Dana P Edelson, et al. 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science. http://circ.ahajournals.org/content/122/18_suppl_3.toc.

4. Sunde, Kjetil, MD, PhD. “Wake up, CPR providers: High-quality CPR is wanted and needed!” American Heart Association. http://my.americanheart.org/professional/ScienceNews/Wake-up-CPR-providers-High-quality-CPR-is-wanted-and-needed_UCM_452907_Article.jsp.

5. Redshaw, Jeffrey D, Benjamin A Stubbs, Carol E Fahrenbruch, Florence Dumas, et al. “Guidelines-based CPR saves more non-shockable cardiac arrest victims.” American Heart Association. April 2, 2012. http://newsroom.heart.org/news/guidelines-based-cpr-saves-more-231197.

6. Highlights of the 2015 American Heart Association Guidelines Update for CPR and ECC. American Heart Association. 2015. http://eccguidelines.heart.org/wp-content/uploads/2015/10/2015-AHA-Guidelines-Highlights-English.pdf.

7. Sugerman, NT, D Herzberg, M Leary, EK Weidman, DL Herzberg, TL Vanden Hoek, et al. “Rescuer fatigue during actual in-hospital cardiopulmonary resuscitation with audiovisual feedback: a prospective multicenter study.” Resuscitation. Sept. 2009. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2746377/.

8. Perkins, Gavin D, Samantha J Brace, and Simon Gates. “Mechanical chest compression devices – current and future roles.” University of Warwick. 2010. http://dx.doi.org/ 10.1097/MCC.0b013e328339cf59.

9. LUCAS™ Chest Compression System Product Brochure. Physio-Control. 2012. http://www.physio-control.com/uploadedFiles/Physio85/Contents/Emergency_Medical_Care/Products/Brochures/LUCAS_Brochure_3303294_B.pdf.

10. LUCAS™ 2 Chest Compression System Instructions for Use. Physio-Control. 2014. http://www.lucas-cpr.com/doc_en/100901-00_Rev_A_LUCAS2_IFU_US_LowRes.pdf.

11. Rubertsson, Sten, Tibor Huzevka, David Smekal, and Jakob Johansson. Abstract 1813: “Early Survival After Cardiac Arrest In A Pilot Study Using The LUCAS Device Compared To Manual Chest Compressions During CPR.” 2007. http://circ.ahajournals.org/cgi/content/meeting_abstract/116/16_MeetingAbstracts/II_386-b?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=rubertsson&searchid=1&FIRSTINDEX=0&volume=116&issue=16+Supplement&resourcetype=HWCIT.

12. Levy M, D Yost, RG Walker, E Scheunemann, SR Mendivea. “A quality improvement initiative to optimize use of a mechanical chest compression device within a high-performance CPR approach to out-of-hospital cardiac arrest resuscitation”. Circulation. 2015; 92:32-37.

13. Rubertsson, Sten, Erik Lindgren, David Smekal, Ollie Östlund, et al. “Mechanical Chest Compressions and Simultaneous Defibrillation vs. Conventional Cardiopulmonary Resuscitation in Out-of-Hospital Cardiac Arrest”. JAMA. January 1, 2014. http://jama.jamanetwork.com/article.aspx?articleid=1774037.

14. Zoll AutoPulse Resuscitation System Model 100 User’s Guide. Zoll. 2012. http://www.zoll.com/medical-products/product-manuals/?pid=9497.

15. Shuster, Michael. Swee Han Lim, Charles D Deakin, Monica E Kleinman, et al. “2010 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science with Treatment Recommendations.” Circulation. 2010. http://circ.ahajournals.org/content/122/16_suppl_2/S338.full.

CONNIE PIGNATARO is a lieutenant for Oakland Park (FL) Fire Rescue. In 2011, she was the first female to be promoted as an officer in Oakland Park. She has a bachelor of applied science degree in public safety administration. She is a certified instructor III, live fire instructor, and vehicle and machine rescue technician. She was introduced to the field of fire rescue as a volunteer for her local Community Emergency Response Team in 1998. She enjoyed her experience so much that she decided to make a career change. She went back to school and, in 2002, she was hired by Oakland Park Fire Rescue.

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