Maximum Chest Compression Research Articles

Appropriate height of dental chairs for effective administration of chest compressions by female dentists.

ObjectivesThe aim of this study was to determine the appropriate height of a dental chair for the administration of effective chest compressions by female dentists.Materials and methodsWe asked 19 female dentists to perform metronome‐guided chest compressions at a rate of 100 compressions per minute for 2 min on the floor and on a dental chair. We set the height of the dental chair to 76, 73, 70, 67, and 64 cm. We measured the compression depth and proportion of compressions performed at an adequate depth. We then compared the quality of chest compressions between the tall and short (relative to the average body height) groups of participants. We also asked the participants to specify their preferred compression height or condition for chest compression administration.ResultsThe participants recorded their maximum chest compression depth (35.0 ± 8.8 mm) at a height of 67 cm. There was no significant difference in chest compression depth between the tall and short groups, irrespective of the compression height. The maximum depth of chest compressions was achieved at a height of 67 cm (from the floor to the compression surface) in both groups, with no significant difference. The participants most frequently identified 67 cm as the most suitable height for the administration of chest compressions.ConclusionFor female dentists, a height of 67 cm is considered suitable for the administration of chest compressions in the standing position, regardless of physique.

A Study of Influential Factors on Chest Compression in Cardiopulmonary Resuscitation from the Perspective of Personnel of Pre-Hospital Emergency of Central Hub in Iran in the First Half Year, 2016

Abstract Introduction: According to the latest guidelines of cardio pulmonary resuscitation (CPR), the American Heart Association, advises 6 centimeters for maximum chest compression in CPR; but unfortunately, so far has not mentioned any explanatory guidelines to factors affecting the amount of chest compression. Therefore, this study was aimed at assessing factors affecting the chest compression cardiopulmonary resuscitation from the perspective of personnel of pre-hospital emergency of central hub in Iran. Methodology: The present study is descriptive analytical conducted randomly among 306 individuals of emergency service personnel in central hub of Iran. Data were collected by self-made questionnaire and analyzed by SPSS, with descriptive statistics (frequency, mean, standard deviation). Results: 306 individuals participated in the study and mean age was calculated as 34.75 +/- 3.45. According to personnel of the emergency service, chest compression in CPR depends on rib curve, skeletal abnormality of chest, injured weight, elasticity of chest and stability of chest and the most influential factor on chest compression was (0.99.34) rib curve. Conclusion: Results of this study show that chest compression is not the same among all individuals and not consistent with instructions of American Heart Association. It is possible that chest compression in CPR is more than 6 centimeters or less than 5 centimeters.

Non-censored rib fracture data during frontal PMHS sled tests

ABSTRACTObjective: The purpose of this study was to obtain non-censored rib fracture data due to three-point belt loading during dynamic frontal post-mortem human surrogate (PMHS) sled tests. The PMHS responses were then compared to matched tests performed using the Hybrid-III 50th percentile male ATD.Methods: Matched dynamic frontal sled tests were performed on two male PMHSs, which were approximately 50th percentile height and weight, and the Hybrid-III 50th percentile male ATD. The sled pulse was designed to match the vehicle acceleration of a standard sedan during a FMVSS-208 40 kph test. Each subject was restrained with a 4 kN load limiting, driver-side, three-point seatbelt. A 59-channel chestband, aligned at the nipple line, was used to quantify the chest contour, anterior-posterior sternum deflection, and maximum anterior-posterior chest deflection for all test subjects. The internal sternum deflection of the ATD was quantified with the sternum potentiometer. For the PMHS tests, a total of 23 single-axis strain gages were attached to the bony structures of the thorax, including the ribs, sternum, and clavicle. In order to create a non-censored data set, the time history of each strain gage was analyzed to determine the timing of each rib fracture and corresponding timing of each AIS level (AIS = 1, 2, 3, etc.) with respect to chest deflection.Results: Peak sternum deflection for PMHS 1 and PMHS 2 were 48.7 mm (19.0%) and 36.7 mm (12.2%), respectively. The peak sternum deflection for the ATD was 20.8 mm when measured by the chest potentiometer and 34.4 mm (12.0%) when measured by the chestband. Although the measured ATD sternum deflections were found to be well below the current thoracic injury criterion (63 mm) specified for the ATD in FMVSS-208, both PMHSs sustained AIS 3+ thoracic injuries. For all subjects, the maximum chest deflection measured by the chestband occurred to the right of the sternum and was found to be 83.0 mm (36.0%) for PMHS 1, 60.6 mm (23.9%) for PMHS 2, and 56.3 mm (20.0%) for the ATD. The non-censored rib fracture data in the current study (n = 2 PMHS) in conjunction with the non-censored rib fracture data from two previous table-top studies (n = 4 PMHS) show that AIS 3+ injury timing occurs prior to peak sternum compression, prior to peak maximum chest compression, and at lower compressions than might be suggested by current PMHS thoracic injury criteria developed using censored rib fracture data. In addition, the maximum chest deflection results showed a more reasonable correlation between deflection, rib fracture timing, and injury severity than sternum deflection.Conclusions: Overall, these data provide compelling empirical evidence that suggests a more conservative thoracic injury criterion could potentially be developed based on non-censored rib fracture data with additional testing performed over a wider range of subjects and loading conditions.

Improving Hybrid III Injury Assessment in Steering Wheel Rim to Chest Impacts Using Responses from Finite Element Hybrid III and Human Body Model

Objective: The main aim of this study was to improve the quality of injury risk assessments in steering wheel rim to chest impacts when using the Hybrid III crash test dummy in frontal heavy goods vehicle (HGV) collision tests. Correction factors for chest injury criteria were calculated as the model chest injury parameter ratios between finite element (FE) Hybrid III, evaluated in relevant load cases, and the Total Human Model for Safety (THUMS). This is proposed to be used to compensate Hybrid III measurements in crash tests where steering wheel rim to chest impacts occur. Methods: The study was conducted in an FE environment using an FE-Hybrid III model and the THUMS. Two impactor shapes were used, a circular hub and a long, thin horizontal bar. Chest impacts at velocities ranging from 3.0 to 6.0 m/s were simulated at 3 impact height levels. A ratio between FE-Hybrid III and THUMS chest injury parameters, maximum chest compression C max, and maximum viscous criterion VC max, were calculated for the different chest impact conditions to form a set of correction factors. The definition of the correction factor is based on the assumption that the response from a circular hub impact to the middle of the chest is well characterized and that injury risk measures are independent of impact height. The current limits for these chest injury criteria were used as a basis to develop correction factors that compensate for the limitations in biofidelity of the Hybrid III in steering wheel rim to chest impacts. Results: The hub and bar impactors produced considerably higher C max and VC max responses in the THUMS compared to the FE-Hybrid III. The correction factor for the responses of the FE-Hybrid III showed that the criteria responses for the bar impactor were consistently overestimated. Ratios based on Hybrid III and THUMS responses provided correction factors for the Hybrid III responses ranging from 0.84 to 0.93. These factors can be used to estimate C max and VC max values when the Hybrid III is used in crash tests for which steering wheel rim to chest interaction occurs. Conclusions: For the FE-Hybrid III, bar impacts caused higher chest deflection compared to hub impacts, although the contrary results were obtained with the more humanlike THUMS. Correction factors were developed that can be used to correct the Hybrid III chest responses. Higher injury criteria capping limits for steering wheel impacts are acceptable. Supplemental materials are available for this article. Go to the publisher's online edition of Traffic Injury Prevention to view the supplemental file.

In-vivo analysis of thoracic mechanical response under belt loading: The role of body mass index in thorax stiffness

Thoracic injuries are a major cause of mortality in frontal collisions, especially for elderly and obese people. Car occupant individual characteristics like BMI are known to influence human vulnerability in crashes. In the present study, thoracic mechanical response of volunteers quantified by optical method was linked to individual characteristics. 13 relaxed volunteers of different anthropometries, genders and age were submitted to non-injurious sled tests (4g, 8km/h) with a sled buck representing the environment of a front passenger restrained by a 3-point belt. A resulting shoulder belt force was computed using the external and internal shoulder belt loads and considering shoulder belt geometry. The mid sternal deflection was calculated as the distance variation between markers placed at mid-sternum and the 7th vertebra spinous process of the subject. Force-deflection curves were constructed using resulting shoulder belt force and midsternal deflection. Average maximum chest compression was 7.9±2.3% and no significant difference was observed between overweight subjects (BMI≥25kg/m²) and normal subject (BMI<25kg/m²). The overweight subjects exhibited significantly greater resultant belt forces than normal subjects (715±132N vs. 527±111N, p<0.05), higher effective stiffness (30.9±10.6N/mm vs. 19.6±8.9N/mm, p<0.05) and lower dynamic stiffness (42.7±8.71N/mm vs. 61.7±15.5N/mm, p<0.05).

An Experimental Study of Chest Compression During Chiropractic Manipulation of the Thoracic Spine Using an Anthropomorphic Test Device

Purpose Chiropractic manipulation of the thoracic spine may induce chest deformations in the anterior-posterior direction. Yet, few studies have examined the biomechanical response of the chest associated with these manipulations. Consequently, an experimental analysis was undertaken to quantify chest compressions resulting from chiropractic thoracic spine manipulations and to estimate amount of risk for injury. Methods A 2-part study approach was used with a Hybrid III anthropomorphic test dummy. In part 1, the dummy was positioned prone on a chiropractic table and subjected to thoracic spine manipulation by 2 experienced doctors of chiropractic. Chest compressions were quantified in the anterior-posterior direction. Manipulation forces were self-selected, with “typical” and “maximum” efforts examined. In part 2, the dummy was positioned beneath a force-instrumented mechanical piston device. Using the piston, chest compressions were induced with magnitudes identical to those recorded during chiropractic manipulation as well as magnitudes sufficient to induce injury. In all trials, force measurements were recorded. Results Thoracic manipulations incorporating the typical and maximum efforts by the chiropractors resulted in maximum chest compressions attaining 1.8% and 4.5% of total chest depth, respectively. According to previously developed correlations between chest compression and injury severity defined using the Abbreviated Injury Scale (AIS), maximum chest compression measured during this study was only 22.7% of the compression required for greater than 10% risk of an AIS 1 injury. Abbreviated Injury Scale 1 level injuries are graded as minor severity and correspond to sternum contusion or fracture of a single rib. Conclusions Results from this preliminary study showed that maximum chest compression during thoracic spine manipulation corresponded to minimal risk of AIS 1 level injuries.

Effects of Body Weight, Height, and Rib Cage Area Moment of Inertia on Blunt Chest Impact Response

Objective: The purpose of this study was to determine the effects of body weight, height, and rib cage area moment of inertia on human chest impact responses in frontal pendulum impacts. Methods: A series of parametric studies was conducted with 11 cases of finite element (FE) analysis using a commercially available three-dimensional (3-D) FE model of the whole human body, Total HUman Model for Safety (THUMS). Selected parameters in this study were body weight, height, and area moment of inertia of the rib cage and of the ribs alone. Three body sizes assumed were those of a large male (AM95), a mid-sized male (AM50), and a small female (AF05). The initial impact response, maximum chest force, maximum deflection, maximum compression ratio, and the number of rib fractures and fractured ribs were examined for statistical analysis. Results: Body weight and height of the human body do not show any correlation with any injury variable considered in this study. However, area moment of inertia of the rib cage correlated (r = −0.86 and p = 0.001) with maximum chest compression ratio, which is the best predictor of the number of rib fractures. Conclusion: The area moment of inertia of the rib cage or ribs alone would affect the response and injury variables in frontal pendulum impacts.

Characterization of Crash-Induced Thoracic Loading Resulting in Pulmonary Contusion

Pulmonary contusion (PC) is commonly sustained in motor vehicle crash. This study utilizes the Crash Injury Research and Engineering Network (CIREN) database and vehicle crash tests to characterize the occupants and loading characteristics associated with PC. A technique to match CIREN cases to vehicle crash tests is applied to quantify the thoracic loading associated with this injury. The CIREN database and crash test data from the National Highway Traffic Safety Administration were used in this study. An analysis of CIREN data were conducted between three study cohorts: patients that sustained PC and any other chest injury (PC+ and chest+), patients with chest injury and an absence of PC (PC- and chest+), and a control group without chest injury and an absence of PC (PC- and chest-). Forty-one lateral impact crash tests were analyzed and thoracic loading data from onboard crash tests dummies were collected. The incidence of PC in CIREN data were 21.7%. Crashes resulting in PC demonstrated significantly greater mortality (23.9%) and Injury Severity Score (33.1 +/- 15.7) than the control group. The portion of lateral impacts increased from 27% to 48% between the control group and PC+ and chest+ cohort, prompting the use of lateral impact crash tests for the case-matching portion of the study. Crash tests were analyzed in two configurations; vehicle-to-vehicle tests and vehicle-to-pole tests. The average maximum chest compression and deflection velocity from the dummy occupants were found to be 25.3% +/- 2.6% and 4.6 m/s +/- 0.42 m/s for the vehicle-to-pole tests and 23.0% +/- 4.8% and 3.9 m/s +/- 1.1 m/s for the vehicle-to-vehicle tests. Chest deflection versus time followed a roughly symmetric and sinusoidal profile. Sixteen CIREN cases were identified that matched the vehicle crash tests. Of the 16 matched cases, 12 (75%) sustained chest injuries, with half of these patients presenting with PC. Quantified loading at the chest wall indicative of PC and chest injury in motor vehicle crash is valuable boundary condition data for bench-top studies or computer simulations focused on this injury. In addition, because PC often exhibits a delayed onset, knowing the population and crash modes highly associated with this injury may promote earlier detection and improved management of this injury.

Limiting performance analysis of a seat belt system with slack

A limiting performance analysis is presented to determine the theoretically optimal control force-time profile generated by a vehicle restraint system, with slack represented as a system delay. Three established injury thresholds (chest acceleration, chest compression rate, and the viscous criterion) and the interior geometry of the vehicle, which defines the system rattlespace, serve as constraints in the analysis. A fourth injury criterion, maximum chest compression, is the performance metric minimized subject to those constraints. Single- and multiple-degree-of-freedom (D.O.F.) models are used, and the limiting performance equations are developed and solved analytically (single-D.O.F.) or numerically (multiple-D.O.F.). Regardless of the magnitude of the system delay, all control forces found with the multiple-D.O.F. model exhibit a short-duration period of high magnitude early in the profile, followed by an interval of nearly constant force. The peak magnitude of the restraining force decreases monotonically with slack, as do all of the injury criteria considered here. Most importantly from the standpoint of restraint system design, this limiting performance analysis shows that the benefits to be gained by pretensioning the belt system are largest over the performance range of current pretensioner technology. Continued refinement in pretensioner response time, through the use of improved crash sensors or faster-acting algorithms, will have a positive effect by reducing injury risk, but the effect should not be expected to be as pronounced as that already realized.

Limiting Performance of Seat Belt Systems for the Prevention of Thoracic Injuries

The theoretically optimal performance of seat belt systems for occupants in automobile frontal crashes is investigated based on a two-mass injury model of the thorax. The performance is measured by thoracic injury criteria which include the maximum chest acceleration, compression and viscous response. The relationship between the best possible performance (limiting performance) of the seat belt system and the distance between the occupant and the interior components of the vehicle is displayed in the form of trade-off curves, which can be used for the evaluation of seat belt performance. The characteristics of the optimal seat belt force and the kinematics of the system are illustrated. The results indicate that the optimal seat belt force is not constant during an impact and that an initial impulse is required. However, constant seat belt force can provide thoracic restraint that is close to the optimal solution.

Limiting performance of seat belt systems for the prevention of thoracic injuries

The theoretically optimal performance of seat belt systems for occupants in automobile frontal crashes is investigated based on a two-mass injury model of the thorax. The performance is measured by thoracic injury criteria which include the maximum chest acceleration, compression and viscous response. The relationship between the best possible performance (limiting performance) of the seat belt system and the distance between the occupant and the interior components of the vehicle is displayed in the form of trade-off curves, which can be used for the evaluation of seat belt performance. The characteristics of the optimal seat belt force and the kinematics of the system are illustrated. The results indicate that the optimal seat belt force is not constant during an impact and that an initial impulse is required. However, constant seat belt force can provide thoracic restraint that is close to the optimal solution.

Thoracic Response and Trauma in Air Bag Deployment Tests with Out-of-Position Small Female Surrogates

The Hybrid III 5th percentile female dummy and seven small female cadavers were instrumented and tested as out-of-position drivers in static air bag deployment tests. Tank test pressure profiles were used to characterize inflator peak pressures and pressure onset rates of two production air bags and a prototype dual-stage system prior to their use in the static deployments. In the out-of-position tests, the chest of die surrogate was positioned in direct contact with the air bag module in an effort to create a worst-case loading environment for the thorax. For the cadavers, post-test radiographs and autopsy investigations identified rib fractures as the most common injury and showed that the number of fractures correlated well with maximum chest compression. The Viscous Criteria exceeded 1.0 m/s in nearly all dummy and cadaver tests but did not correlate well with the severity level of observed cadaver injury which was largely determined by hard-tissue rather than soft-tissue trauma. Statistical analysis of the injury, severity relative to the air bag and test parameters suggests that the pressure onset rate of the inflator is more important than peak pressure in determining the severity of out-of-position injuries and should be given primary consideration in inflator depowering efforts. Statistical comparison of dummy and cadaver responses indicates acceptable biofldelity of the Hybrid III small female dummy.

Thoracic deformation and velocity analysis in frontal impact.

The objective of the present study was to measure dynamic chest deformations and compute chest velocity and viscous criterion during real world frontal impacts conducted on a horizontal sled. Four unembalmed human cadavers were restrained using a three-point belt restraint in the driver seat of a sled buck. Two chest bands (each with a 24 gauge capability) were placed on the thorax to record the temporal deformation patterns during impact. All tests were conducted at a velocity of approximately 50 kph. Biomechanical data were gathered digitally at a sampling rate of 12,500 Hz. Multiple rib fractures were identified in all specimens at autopsy. Analysis of approximately 800 temporal deformation contours of the thorax demonstrated regional differences. The overall mean maximum normalized chest deflections, maximum chest compression velocities, and peak viscous response variables ranged from 0.15 to 0.51, 1.79 to 4.87 m/s, and 0.15 to 1.95 m/s, respectively. These findings clearly illustrate the potential use of the chest band output to correlate injury with biomechanical variables and establish thoracic impact tolerance.

Biomechanics of injury in lateral impacts

Fourteen anesthetized swine were subjected to blunt lateral impact at velocities of 4.3, 6.7, or 8.2 m/s with a 15 cm flat pendulum weighing 23.4 kg accelerated to impact speed by a power-assisted pneumatic impactor. Injuries consisted of laceration of the liver and spleen resulting in severe hemoperitoneum and death by ventricular fibrillation and respiratory arrest in the highest severity impacts. Logist analysis of the biomechanical responses and serious or fatal injury indicated that the maximum Viscous response ( VC) had the best correlation with injury risk. A tolerance level of VC = 0.89 m/s was determined for a 25% probability of serious injury. In contrast, maximum chest compression did not correlate with injury. The experiments indicate that internal organ and soft tissue injury may occur by a Viscous mechanism during the rapid phase of compression of the body. The Viscous response is an effective measure of injury risk in side impacts.

Resuscitation in late pregnancy.

This paper considers cardiopulmonary resuscitation in obstetric patients at term and the influence of aortocaval compression on the outcome. The maximum chest compression force produced by eight physicians was measured as a function of angle of inclination using an inclined plane. The compression force at an angle of 27 degrees is 80% of that in the supine position and the Cardiff resuscitation wedge, designed to prevent aortocaval compression, is described with this inclination. Midwives' expertise in basic life support 6 months after instruction was assessed using a manikin simulator. The majority had acquired errors in external chest compression and mouth to mouth ventilation. These were corrected by additional tuition. Resuscitation of the manikin on the Cardiff wedge was found to be as efficient as in the supine position.

Visualization of cardiac valve motion in man during external chest compression using two-dimensional echocardiography. Implications regarding the mechanism of blood flow.

Five patients who underwent cardiopulmonary resuscitation (CPR) were studied by two-dimensional echocardiography to assess valve motion. The mitral valve remained open throughout the entire compression-release cycle of CPR. The aortic valve opened during the compression phase of CPR and closed during the release phase. The pulmonic valve moved toward the closed position during the compression phase and the valve leaflets opened during release. Tricuspid valve leaflets never completely apposed, even during maximum chest compression, and they were widely open during release. Left ventricular dimensions did not change appreciably during CPR. These findings support the theory that forward blood flow during CPR depends on a generalized increase in intrathoracic pressure and not on direct compression of the heart itself. The left heart appears to act as a conduit for passage of blood, and mitral valve closure is not necessary for forward blood flow during CPR.