Article, Emergency Medicine

Comparison of chest compression kinematics associated with over-the-head and standard cardiopulmonary resuscitation

Brief Report

Comparison of chest compression kinematics associated with over-the-head and standard cardiopulmonary resuscitation?

Chih-Hsien Chi MD a, Jui-Yi Tsou b c, Fong-Chin Su PhD b,?

aDepartment of Emergency Medicine, National Cheng Kung University, Tainan, Taiwan bInstitute of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan cDepartment of Physical therapy, Fooyin University, Kaohsiung, Taiwan

Received 23 July 2008; revised 29 August 2008; accepted 29 August 2008


Background: Over-the-head cardiopulmonary resuscitation (CPR) is a method of chest compression, which may be easier to perform than standard CPR in a confined space.

Purpose: The purpose of this study was to evaluate the effects of over-the-head CPR on the kinematics and the force of delivered compressions.

Methods: The subjects were 21 health care providers who were experienced in CPR. Each participant performed over-the-head CPR (O) and standard CPR (S). The compression-to-ventilation ratio was 30:2. The CPR duration was 2 minutes in each position, with a rest period of 15 minutes between each instance. The order in which positions were adopted was randomized. A manikin was equipped with a 6-axial force load cell to collect 3-dimensional compression forces at a sampling rate of 1000 Hz. An 8-camera digital motion analysis system was used to collect 3-dimensional trajectory information. Data were compared by Crossover design analysis of variance (P b .05 represents statistical significance).

Results: No significant differences in range of motion of the head, shoulder, lower trunk, hip, and knee were obtained using the 2 methods. The compression forces in O and S were 386.64 +- 47.32 and 397.35 +-

41.89 N, respectively (P N .05). No significant differences between the compression frequencies, depths, and percentages correct were obtained using the 2 methods.

Conclusions: There were no differences between the kinematics, compression forces, depths, and frequencies obtained using the O and S CPR methods as practiced by experienced providers.

(C) 2009


? The authors would like to thank National Science Council of the Republic of China, Taiwan, for financially supporting this research under contract no. NSC 94-2320-B-006-041.

* Corresponding author. Tel.: +886 6 2760665; fax: +886 6 2343270.

E-mail address: [email protected] (F.-C. Su).

early cardiopulmonary resuscitation (CPR) is an impor- tant action in the Chain of survival for cardiac arrest [1-3]. However, a normal cardiac output could not be obtained even when chest compression is correctively and optimally performed [4]. This condition is worsened when the CPR

0735-6757/$ – see front matter (C) 2009 doi:10.1016/j.ajem.2008.08.029

is implemented or performed in a confined space, for example, in the ambulance.

There has been little prior work on the effects of rescuers of performing CPR in a confined space. Recently, an alternative method called over-the-head CPR has been developed for such conditions [5]. Unlike in standard CPR, in which the rescuers must place a knee above and beside the head of the victim to perform ventilation and chest compression, in this approach, the CPR provider need not move their body during alternate chest compression and ventilation. Investigations have demonstrated that the efficiency of over-the-head CPR is as good as or even better than that of standard CPR [5-8].

Most research on CPR techniques discusses the effects of motion (performance outcome), compression depth, com- pression rate, and cyclic time [9,10]. However, the position of the rescuer may affect the muscle recruitment and therefore the performance of CPR [11]. The hypothesis of this study is that the effect that positioning might have on standard vs over-the-head CPR, that is, the position affects the kinematics (angle of motion) and kinetics (forces delivered, depth, and frequency) during CPR. This work thus explores the effect of motion on the performance of chest compression. The goal of this work was to compare over-the-head CPR with standard CPR to investigate the kinematics and kinetic factors of the over-the-head CPR on manikin model.

Materials and methods

Study design

This experiment was performed using a crossover design. It was approved by the Human Ethics Committee of the National Cheng Kung University Hospital (Tainan, Taiwan). All subjects provided informed and written consent.

Twenty-one emergency medical professionals, compris- ing 15 male emergency medical technician firefighters and 6 female emergency department registered nurses from a university medical center, participated voluntarily. All subjects were experienced in prehospital or in-hospital standard CPR. The approach follows that demonstrated by our group earlier [11].

Study protocol

The participants had no muscular skeletal injury, sprain, or pain. No food was eaten 30 minutes before the tests. The ingestion of alcohol, tea, and coffee was prohibited on the day of each test. The study was performed at the motion analysis laboratory of the Department of Medical Engineer- ing. The participants, who were all experienced emergency health care providers, reviewed both methods on manikins before they began the tests.

Each participant then performed CPR in 2 positions– standard CPR while kneeling beside the Resusci Anne

manikin (Laerdal Medical, Wappingers Falls, NY) placed on the floor and over-the-head CPR on the floor. The compression-to-ventilation ratio was 30:2 simulating 2 person CPR following 2005 Basic Life Support (BLS) guidelines [12]. The External Cardiac Compression (ECC) duration was 2 minutes in each position, alternating with rest periods of 15 minutes. The order of the adopted positions was randomized. To maintain the compression rate for more than 100/min, a metronome was used as the audio prompt in every ECC position. Other compression variables were recorded by using the Laerdal Resusci Annie manikin. Participants were blind to the values of the parameters in the study.

Motion analysis

Three-dimensional motion analysis was performed to define and compare the motions of the joint angles. An image-based motion analysis system was adopted with markers’ reflecting light back to sensors. A similar 3- dimensional motion analysis was used to define patterns of joint motion in a study of various Musculoskeletal problems, which are generally linked to repetitive motion.

To record the movements, a set of reflective markers were placed on selected anatomical landmarks on the surface of the body of each subject. Thirty-seven passively reflective markers were placed on selected anatomical landmarks on the right upper extremity, head, trunk, and bilateral lower extremity of each subject to determine the embedded axes of segments. The linkage diagram of reflective markers for motion analysis was shown in Fig. 1. In addition, three marks were placed on the load cell to define the coordinate system of the cell. A video-based motion system with 8 Motion Analysis HiRes cameras (Motion Analysis Corp, Santa Rosa, Calif) recorded the marker motion, with high- resolution and complex motion capturing. The presented data show both the compression and the decompression phases, and the results represent the mean average angle measured during a period of 20 seconds. The light-reflective marker positions in 3-dimensional space were captured and quantified using a charge-coupled device and Motion Analysis EVA software (Motion Analysis Corp, Santa Rosa, Calif). The operating software of the system gathers the 2-dimensional camera images and processes the data to 2- dimensional or 3-dimensional assessments [11].

Delivery of compression forces

The manikin was equipped with a 6-axial force transducer (AMTI MC3A-6-1000, Advanced Mechanical Technology Inc, Watertown, Mass) to measure 3-dimensional compres- sion forces at a sampling rate of 1000 Hz. This transducer was fixed to the sternum of the manikin. The transducer was

7.62 cm (3 in) high, so the rescuers were placed 7.62 cm (3 in) above the floor of the laboratory on a flat wood box to reach a similar height to that of ordinary manikin operation.

Fig. 1 Linkage diagram of reflective markers for motion analysis. A, lateral view; B, front view; and C, oblique view.

Data analysis

The data on joint angles and compression forces were obtained during the middle cycles of the CPR session. Suppose a difference of 5% in percent change of compres- sion force is considered of Clinically meaningful difference. By using crossover design, assuming that the SD is 10%, the

required sample size to achieve an 80% power at ? = .05 for correctly detecting such difference is more than 16. The means and SDs of the demographic and outcome variables were obtained and presented. Data were analyzed using SPSS version 13 (SPSS, Chicago, Ill). Statistical significance was set at P b .05 throughout the experiment. Descriptive statistics were obtained, and a paired t test was conducted to

Fig. 2 Cyclic dynamic changes in joint angles during chest compression. No difference existed between cyclic movement patterns of over- the-head and standard groups.

Table 1 Range of motion (joint angles, in degree) associated with various positions (over-the-head and standard)




Mean +- SD


Mean +- SD

Mean difference

95% confidence interval

Upper Lower




5.60 +- 3.17

5.53 +- 3.30


-0.54 0.67


Upper trunk


2.05 +- 0.88

2.00 +- 0.87


-0.24 0.34



0.86 +- 0.46

0.94 +- 0.73


-0.35 0.21



0.85 +- 0.35

0.7 +- 0.22


0.01 0.28

.03 ?

Lower trunk


1.83 +- 1.58

1.96 +- 1.73


-0.46 0.18



0.67 +- 0.29

0.73 +- 0.27


-0.20 0.09



0.49 +- 0.24

0.53 +- 0.24


-0.15 0.06




3.18 +- 1.20

3.03 +- 1.03


-0.32 0.63



2.66 +- 1.41

2.72 +- 1.62


-0.57 0.44



2.12 +- 1.13

2.08 +- 1.71


-0.50 0.58




6.16 +- 3.89

5.93 +- 3.67


-0.61 1.07




4.65 +- 2.27

4.66 +- 2.84


-0.91 0.88




12.28 +- 3.62

12.31 +- 3.60


-0.69 0.64



1.03 +- 0.69

0.93 +- 0.50


-0.17 0.36



4.48 +- 2.51

4.22 +- 2.28


-0.44 0.96




3.72 +- 1.80

4.20 +- 1.76


-0.95 0.00




3.76 +- 3.42

2.94 +- 2.74


0.01 0.61


* P b .05 as significant.

study the difference between the joint angles and the compression forces obtained using the 2 methods. The effect was significant as P b .05.


The mean age of the participants was 28.5 +- 4.1 years old, their mean height was 168.6 +- 6.9 cm, and their weight was

68.0 +- 10.5 kg. Fig. 2 indicates that the cyclic dynamic change of the joint angles during chest compression was similar. No difference existed between the cyclic motion patterns of the over-the-head and standard group. Almost all range of motion (joint angles, in degree) associated with various positions indicated no significant change in angles during the middle cycle of the CPR session (Table 1). The only significant difference was between the angles of the upper trunk in over-the-head and standard groups (0.85 +- 0.35 vs 0.70 +- 0.22; P = .03). The mean compression force

(Newton) of the over-the-head and standard groups were

386.64 +- 47.32 and 397.35 +- 41.89, respectively (P N .05). Table 2 presents the performance outcome associated with various positions. The average compression depth, average compression rate, and percentage correct (%) compression did not differ significantly between the over-the-head and standard groups.


The principal finding in this study is that rescuers performing chest compressions on a manikin deliver similar forces, kinematics, and performance whether they use the standard or over-the-head technique.

A previous study by Handley [5] demonstrated that the mean compression depth was significantly less, more compressions of incorrect depth occurred, and poor Hand placement was more likely when the over-the-head method

Table 2 Performance outcome in various positions (over-the-head and standard)

Performance outcome




95% confidence




Mean +- SD

Mean +- SD

Upper Lower

Average compression rate (time/min)

111.14 +- 16.60

110.23 +- 15.26


-3.11 4.92


Average depth (mm)

47.14 +- 3.07

47.47 +- 3.50


-1.87 1.20


Average number per min

112.80 +- 20.79

109.76 +- 15.75


-1.59 7.69


Percentage correct (%)

64.61 +- 34.95

59.71 +- 40.30


-5.92 15.73


Too deep

5.19 +- 8.14

7.66 +- 10.75


-5.84 0.89


Too shallow

0.76 +- 0.80

0.83 +- 1.07


-0.55 0.46


was used. The authors suggested that additional training may be required before the technique can be safely implemented. Our work compares these 2 methods by kinematic measure- ment and of manikin output. The only difference between the over-the-head and standard methods was in the upper trunk rotation angle. However, this measured difference between angles was less than 1? and may not be clinically significant. The reason for this variation is that during standard CPR, even in 2-person resuscitation, the rescuer turns toward the head of the victim to evaluate him or her, which may explain the larger angular change in the standard position.

The percentages of correct compressions obtained using these 2 methods were similar. The results and data herein were similar to those of earlier studies in both positions, perhaps indicating that over-the-head CPR is of a similar quality to standard position CPR [13-16]. The compression force delivered and other parameters support this assertion. The motion analysis system here was used to define patterns of joint movement of various musculoskeletal problems, usually related to repetitive motion [13]. This study differed from previous over-the-head CPR studies in setting out to compare angles of joint motion and compres- sion force between the 2 techniques. The rationale for measuring these parameters is based on the cyclical move- ment of CPR that results in repetitive thoracolumbar excursion [17-19]. The clinical relevance for measuring

these parameters warrants further investigations.

This study has limitations. First, the ventilation variables in over-the-head and standard CPRs were not evaluated. Second, the hand-off times were not studied because of limitations of the equipment software. Third, the participants were clinical experts in chest compression in a simulation environment; the effect of kinematics variables associated with bystander-level rescuers using the over-the-head technique on a manikin model is unknown.

In this study, we have identified several previous studies that have compared standard to over-the-head CPR and on the whole found them to be equivalent in compression efficacy. No differences existed between the kinematics, compression forces, depths, and frequencies obtained using over-the-head and standard CPR methods as performed experienced providers.


Ted Knoy is appreciated for his editorial assistance.


  1. Kouwenhoven WB, Jude JR, Knickerbocker GG. Closed-chest cardiac

massage. JAMA 1960;173:1064-7.

  1. Cobb LA, Weaver WD, Fahrenbruch CE, Hallstrom AP, Copass MK. Community-based interventions for sudden cardiac death. Impact, limitations, and changes. Circulation 1992;85(1 Suppl):I98-I102.
  2. Guidelines for cardiopulmonary resuscitation and emergency cardiac care. Emergency Cardiac Care Committee and Subcommittees, American Heart Association. Part II. Adult basic life support. JAMA 1992;268(16):2184-98.
  3. Weale FE, Rothwell-Jackson RL. The efficiency of cardiac massage. Lancet 1962;1(7237):990-2.
  4. Handley AJ, Handley JA. Performing chest compressions in a confined

space. Resuscitation 2004;61(1):55-61.

  1. Perkins GD, Stephenson BT, Smith CM, Gao F. A comparison between over-the-head and standard cardiopulmonary resuscitation. Resuscitation 2004;61(2):155-61.
  2. Hupfl M, Duma A, Uray T, et al. Over-the-head cardiopulmonary resuscitation improves efficacy in basic life support performed by professional medical personnel with a single rescuer: a simulation study. Anesth Analg 2005;101(1):200-5 [table of contents].
  3. Bollig G, Steen PA, Wik L. Standard versus over-the-head cardio- pulmonary resuscitation during simulated advanced life support. Prehosp Emerg Care 2007;11(4):443-7.
  4. Larsen PD, Perrin K, Galletly DC. Patterns of external chest compression. Resuscitation 2002;53(3):281-7.
  5. Dorph E, Wik L, Stromme TA, Eriksen M, Steen PA. Quality of CPR with three different ventilation: compression ratios. Resuscitation 2003;58(2):193-201.
  6. Chi CH, Tsou JY, Su FC. Effects of rescuer position on the kinematics of cardiopulmonary resuscitation (CPR) and the force of delivered compressions. Resuscitation 2008;76(1):69-75.
  7. Hazinski MF, Nadkarni VM, Hickey RW, O’Connor R, Becker LB, Zaritsky A. Major changes in the 2005 AHA Guidelines for CPR and ECC: reaching the tipping point for change. Circulation 2005;112(24 Suppl):IV206-11.
  8. Hightower D, Thomas SH, Stone CK, Dunn K, March JA. Decay in quality of closed-chest compressions over time. Ann Emerg Med 1995;26(3):300-3.
  9. Ochoa FJ, Ramalle-Gomara E, Lisa V, Saralegui I. The effect of rescuer fatigue on the Quality of chest compressions. Resuscitation 1998;37(3):149-52.
  10. Deschilder K, De Vos R, Stockman W. The effect on quality of chest compressions and exhaustion of a compression-ventilation ratio of 30: 2 versus 15:2 during cardiopulmonary resuscitation–a randomised trial. Resuscitation 2007;74(1):113-8.
  11. Greingor JL. Quality of cardiac massage with ratio compression- ventilation 5/1 and 15/2. Resuscitation 2002;55(3):263-7.
  12. de Looze MP, van Greuningen K, Rebel J, Kingma I, Kuijer PP. Force direction and physical load in dynamic pushing and pulling. Ergonomics 2000;43(3):377-90.
  13. Elble RJ, Leffler K. Pushing and pulling with the upper extremities while standing: the effects of mild Alzheimer dementia and Parkinson’s disease. Mov Disord 2000;15(2):255-68.
  14. Chan SP, Luk TC, Hong Y. Kinematic and electromyographic analysis of the push movement in tai chi. Br J Sports Med 2003;37(4):339-44.

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