Automated vs Manual Chest Compressions in Out-of-Hospital Cardiac Arrest

Background Information:

Out of hospital cardiac arrest (OHCA) is a medical emergency that requires immediate intervention to increase the chance of survival. The global survival rate of OHCA patients who received CPR has increased in the past 40 years [1]. However, CPR related rib and sternal injuries are observed more frequently in OHCA and are an independent factor in mortality [2]. We’ve reviewed prior literature on this before on REBEL EM that can be found here. Since then more evidence has emerged that suggests no significant difference in clinical outcome when mechanical chest compression device was compared with manual chest compression, however large scale studies are still in need [3]. The authors of this study sought to evaluate the rate of ROSC, frequency of CPR related injuries, duration of CPR and rate of survival between automated chest compression devices (ACCD) vs manual chest compressions (mCC) on resuscitation among out of hospital cardiac arrest based on the admission time.

Paper: Takayama W, et al. Manual Chest Compression versus Automated Chest Compression Device during Day-Time and Night-Time Resuscitation Following Out-of-Hospital Cardiac Arrest: A Retrospective Historical Control Study. J Pers Med. 2023 Jul 28; PMID: 37623453 

Clinical Question:

• What is the impact of automated chest compression devices (ACCD) vs manual chest compressions (mCC) on the rate of ROSC, frequency of CPR related chest injuries and duration of in-hospital cardiopulmonary resuscitation (IHCPR)?

What They Did:

• This was a retrospective historical control study at a single academic center located in Tokyo, Japan done between 1 April 2015 to 31 March 2022
• Patients were divided based on time of admission, day time (07:00 – 22:59) and night time (23:00-06:59)
• Pre hospital assessment by Japanese EMS system with constant quality assessment
• Method of chest compressions on arrival at the ED was formally changed on May 1 2020 where automated mechanical compressions replaced manual compressions
• CPR and post-cardiac arrest care (including targeted temperature management) were provided consistently in accordance with the 2015 or 2020 AHA and ERC Guidelines for CPR
• The Lund University Cardiac Assist System 3 (LUCAS 3) was used for in-hospital resuscitation after 1 May 2020
• Further division of groups based on resuscitation device
  • automated chest compression devices (ACCD) from 1 May 2020 to 31 March 2022
  • manual chest compressions (mCC) from 1 April 2015 to 31 April 2020
• IHCPR duration was defined as the interval between ED arrival and termination of resuscitation or ROSC and ROSC is defined as the return of spontaneous circulation that lasted at least 5 minutes
• OHCA was defined as cardiac arrest that occurred out-of-hospital, with the patient being unresponsive to stimulation, gasping or not breathing, and having carotid arteries without a palpable pulse for a maximum assessment interval of 10 seconds
• OHCPR duration was defined as the interval between EMS dispatch and ED arrival in cases with bystander CPR or the interval between EMS arrival at the scene and ED arrival in cases without bystander CPR
• CPR related chest injuries included rib and sternal fractures, pleural effusion/ hemothorax or pneumothorax
• CPR related injury data was collected from the patients’ medical records and 64-slice computed tomography (CT) imagery
• The hospital has a general policy of routinely performing CT after CPR to identify the cause of cardiac arrest in non-traumatic cases. The CT findings were interpreted by ≥2 board-certified emergency physicians and one radiologist

Inclusion Criteria:

• Age 18 years old and above
• Patients who experienced out-of- hospital cardiac arrest and transferred to Tokyo Medical and Dental University Hospital within a specified time frame

Exclusion Criteria:

• Patients with DNR orders
• Patients whose cardiac arrest was due to trauma
• Open – chest CPR
• Patients who did not undergo chest computed tomography ( CT) examination
• Missing or insufficient data regarding
  • CPR duration
  • Witness status
  • Initial rhythm
• Patients not suitable for mechanical CPR such as those with severe cachexia, morbid obesity or chest wall deformity
• Received CPR using an automated chest compression device after ED arrival before 1 May 2020

Outcomes:

Primary

• Rate of return of spontaneous circulation (ROSC)
• Frequency of CPR related chest injuries
• Duration of IHCPR

Secondary

• Rate of survival to ED discharge
• Rate of survival to hospital discharge
• Rate of survival with good neurological outcomes to hospital discharge
  • Cerebral performance category ( CPC ) score was used to classify neurological outcome into five classes
  • (1) full recovery or mild disability; (2) moderate disability but independent in activities of daily living; (3) severe disability with dependence for support in activities of daily living; (4) persistent vegetative state; and (5) death. CPC scores of 1 or 2 indicate good neurological outcomes, while CPC scores of 3 or 4 indicate poor outcomes

Results:

Critical Results:

Strengths:

• Adjusted for confounding factors by incorporating age, sex, witnessed status, bystander CPR status, initial rhythm ( shockable or not), cause of cardiac arrest and OHCPR duration as explanatory variables in multivariable models.
• Patient were enrolled in a consecutive manner as opposed to convenience sampling which helps limit selection bias
• Comprehensive patient data to include patients who underwent CT examinations
• Use of mechanical device for in hospital resuscitation could offer better clinical approach in unstable and during nighttime resuscitations
• Asks a clinically relevant question that could assist low staffed clinical settings both geographically and overnight shifts
• Utilized the latest AHA and CPR and Post -arrest care guidelines
• Patient oriented outcomes of survival to discharge with a CPC score
• Changed the definition of ROSC to be more patient and clinically relevant
• CPR related injuries determined by CT scans
• Exclusions of patients with missing or insufficient data regarding study variables
• Definition of ROSC (return of spontaneous circulation) as > 5 minutes differing from Utstein style guidelines which recommend > 30 seconds due to limitations in clinical data recording intervals in electronic medical records

Limitations:

• Retrospective observational study with limited sample size raising concerns about residual confounding and type II error.
• There was no sample size calculation which could have adversely affect the overall power of the study
• The split of their day and night time hours was uneven and thus will lead to more patients to be admitted during the day
• Single country with healthcare system which limits external validity and generalizability
• No clear identification of bystander occupation or whether they had any medical training
• The use of only one type of mechanical compressions device LUCAS 3 as opposed to others which may have been more effective thus adding to the bias
• Lack of clear explanation for terminating resuscitation in the ED
• Impact of COVID -19 pandemic on out of hospital cardiac arrest was not considered
• The rates of bystander CPR and neurologically favorable outcomes after OHCA reportedly decreased during the COVID-19 pandemic
• Lack of any post discharge or follow up interview process to ensure adequate neurological outcomes

Discussion:

• The study found nighttime cases, ACCD usage led to longer resuscitation durations, fewer CPR related chest injuries and better clinical outcomes compared to manual chest compressions.
• Patients who require a procedure (i.e. cardiac catheterization, ECMO, etc and settings where high quality CPR performance can not be maintained with manual compressions (i.e. limited man/woman power, staff safety, etc..) use of ACCD is a reasonable approach.
• There is a disproportionate number of subjects in the day vs night time that can result in misleading conclusions
• It is difficult to assess the quality of bystander quality and skill in performing the CPR, can alert the rate of ROSC achieved.
• Hospital policy of routine CT after CPR to identify causes of cardiac arrest in non traumatic cases, however does not comment on other injuries noted except rib fractures, sternal fractures, pleural effusion/hemothorax, or pneumothorax.
• Use of only LUCAS 3 for mechanical CPR in hospital settings,  hence results may not be extrapolated to other types of mechanical CPR devices.
• Does not comment on what documentation was used for the DNR status confirmation.
• Termination of resuscitation in the field by EMS can contribute to survival bias while comparing mechanical CPR to manual.
• Possibility of poor CPR quality depending on respondents skill, transportation time and time of the day can contribute to the variations in results.
• COVID impact on using mechanical CPR intervention could have delayed the time to CPR.
• The number of providers to nursing staff to the patient ratio during day vs night time can contribute to variations in results.
  • The staffing model was as follows:
    • Day time included > 2 board certified emergency physicians, 3 medical interns and 3 nurses
    • Night time included 1 board certified emergency physician, 3 medical interns and 2 nurses
• Overall, the study uses current accepted CPR guidelines, clearly defines all study variables, and has an appropriate timeline for gathering data. However, the study has low external validity due to use of specific equipment for mechanical CPR, questionable skill of CPR providers, single center and discrepancy in data collection.

Author’s Conclusions: 

• Patients who underwent ACCD during in-hospital resuscitation at night had a significantly longer duration of in-hospital resuscitation, a lower incidence of CPR-related chest injuries, and better outcomes.

Our Conclusion:

• In conclusion, findings of this retrospective control study provides effectiveness of using automated chest compression devices for in hospital resuscitation especially during night time. Patients who underwent outside hospital cardiac arrest and had resuscitation using a mechanical compression device had longer durations of resuscitation, lower incidence of CPR related chest injuries and better clinical as well as neurological outcomes compared to manual compression group. However, given the limitations in sample size, lack of descriptors of terminating resuscitation and differences in defining day vs night time there is a need for further studies that can explore these differences.

Clinical Bottom Line:

• This study suggests that ACCD use during night time resuscitations lead to lower CPR related chest injuries, improves the rates of ROSC and ultimately better survival with improved neurological outcomes. Although there are many variables that could account for these results, this trial supports the use of ACCD and can be extrapolated to patients who require a procedure (i.e., cardiac catheterization, ECMO, etc) where CPR duration may need to be longer and settings where high quality CPR performance can not be maintained with manual compressions (i.e., limited man/woman power, staff, safety etc).

Guest Post By:

Ravali Kundeti, DO
PGY-2, Emergency Medicine Resident
RWJBH Community Medical Center, Toms River, NJ
Twitter / X : @Ravali1401

Mark Ramzy, DO
Emergency Medicine Attending and Cardiothoracic Intensivist
Clinical Assistant Professor of Emergency Medicine
Rutgers Health / RWJBH Community Medical Center, Toms River, NJ
Twitter: @MRamzyDO

REFERENCES:

1. Yan S, et al. The global survival rate among adult out-of-hospital cardiac arrest patients who received cardiopulmonary resuscitation: a systematic review and meta-analysis. Crit Care. 2020 Feb 22 ; PMID: 32087741
2. Karasek J,et al. CPR-related injuries after non-traumatic out-of-hospital cardiac arrest: Survivors versus non-survivors. Resuscitation. 2022 Feb;  Epub 2022 Jan 5. PMID: 34995685
3. Liu M, Shuai Z, et al. Mechanical chest compression with LUCAS device does not improve clinical outcome in out-of-hospital cardiac arrest patients: A systematic review and meta-analysis. Medicine (Baltimore). 2019 Nov PMID: 31689757

For More Thoughts on This Topic Checkout:

• REBEL EM CPR in OHCA: Man vs Machine

Post Peer Reviewed By: Salim Rezaie, MD (Twitter/X: @Srrezaie)