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At least 631 records · Page 35Linked to original sources
PubMed1998

QT interval dispersion: dispersion of ventricular repolarization or dispersion of QT interval?

The QT interval (QTI) has long been useful as a clinical index of the duration of ventricular repolarization, particularly as a marker of prolonged repolarization and its well-established association with arrhythmogenic cardiac states. Likewise, inhomogeneity (dispersion) of repolarization has been linked definitively to increased susceptibility to reentrant arrhythmias. Recent studies have reported the use of QTI dispersion as a meaningful clinical index to identify patients at risk, but the interpretation of the measurement has been controversial. A Langendorff-perfused, isolated canine heart suspended in a torso-shaped, electrolytic tank filled with NaCl-sucrose solution was used to investigate the relationship between body surface QTIs and ventricular repolarization measured directly from the cardiac surface by using activation-recovery intervals, which have been documented to reflect the duration of local action potentials as well as local refractory periods. The data showed poor correlation between cardiac surface activation-recovery intervals and QTIs, as well as the insensitivity of QTIs to regional repolarization shortening in the presence of prolonged repolarization elsewhere. Furthermore, the data confirmed that torso tank QTI dispersion does not reflect directly the full range of measured ventricular repolarization inhomogeneity. It is concluded that body surface QTI dispersion is not a reliable index of repolarization dispersion.

Action Potentials↗
PubMed1998

A comparison of simulated QRS isointegral maps resulting from pacing at adjacent sites: implications for the spatial resolution of pace mapping using body surface potentials.

The precise localization of ventricular tachycardia (VT) foci is a prerequisite for the successful radiofrequency catheter ablation in patients. The purpose of this study was to systematically quantify over what distance adjacent sites in the right ventricular (RV) and left ventricular (LV) epicardium and LV endocardium could be distinguished by inspecting morphological features of QRS isointegral maps using statistical methods. We investigated the spatial resolution of QRS isointegral maps by means of an anatomically accurate computer model of the human ventricular myocardium that incorporates a bidomain model for simulating the realistic activation sequences and the oblique dipole model in combination with the boundary element method for calculating extracardiac potentials. In this model, we initiated activation sequences at a total of 183 epicardial and 75 LV endocardial pacing sites, positioned in three levels (basal, middle, and apical). For each of the 258 pacing sites, we calculated a set of 10 QRS isointegral maps with added Gaussian noise at 117 leads (covering the anterior and posterior torso) and at 32 leads (covering only the anterior torso), respectively. Sets of maps were then cross correlated and root-mean-square (RMS) values of difference maps were calculated for all possible pairs of pacing sites on the same level. We applied the nonparametric unpaired Kolmogorov-Smirnov test and defined the spatial resolution as the pacing site separation at which the differences in correlation coefficients and RMS differences were significant (level P < .05). We observed significant differences in maps when the distances between pacing sites were on average (+/- SD) greater than 4.3 +/- 1.0 mm. In more than 90% of pacing sites, the significant differences in maps were observed within 4 mm even when using a 32-lead mapping system. The findings of our study provide theoretical evidence that QRS isointegral maps may offer noninvasive means for preinterventional planning of the ablative treatment in localizing both endocardial and epicardial sites of origin of VT.

Body Surface Potential Mapping↗
PubMed1999

Paradoxical QRST integral changes with ventricular repolarization dispersion.

Body surface QRST integral (QRSTI) maps have been shown theoretically to reflect disparity of intrinsic repolarization properties and have been experimentally linked to increased arrhythmia susceptibility. Paradoxically, a lower magnitude of QRSTI in patients with heart disease and at risk for arrhythmias has been reported. We hypothesized that this paradoxical reduction in QRST magnitude is a consequence of increased heterogeneity of repolarization gradients in normal hearts. We generated QRSTI using a previously published heart model to compare QRSTI for aligned and random repolarization gradients. The heart model consisted of 50,000 cubic units in an anatomically correct arrangement that included parameters to simulate anisotropic conduction and inhomogeneous distribution of refractoriness. Body surface potential maps (BSPMs) were generated on a torso surface assuming a homogeneous torso and using the boundary element method for normal alignment of repolarization gradients and spatially reassigned repolarization values that randomized repolarization directions. QT duration was measured by the subtraction of Q onset time from T offset time on the BSPM. T offset was defined as the last potential to be detected at intervals of 3 ms that was above the threshold of 0.1 mV during recovery. The time of T offset showed a consistent tendency to shift to the left posterior and to split. When slow conduction velocities were assigned, BSPMs showed delayed propagation and multiple extrema. QRSTI showed systematic magnitude decrease with increasing randomness of repolarization gradient direction. Ventricular fibrillation (VF) could be induced by successive extrastimuli under the conditions of over 70% deviation and slow conduction of 0.5 m/s for the longitudinal direction. In conclusion, a possible explanation for the paradoxical reduction in QRSTI in the presence of constant repolarization disparity is the change in alignment of repolarization gradients.

Body Surface Potential Mapping↗
PubMed1999

Localization of intramural necrotic regions using electrocardiographic imaging.

Recent studies have demonstrated that electrocardiographic imaging (ECGI) is a novel noninvasive modality for exploring the spread of electrical activation within the ventricular wall. In this study, our goal was to explore the ability of ECGI in reconstructing epicardial potentials and electrograms in the ventricles damaged by localized necroses (<2 cm2). An anatomical model of the human ventricular myocardium was used to simulate activation sequences initiated at 428 epicardial and endocardial pacing sites distributed over the right ventricular and left ventricular free walls. From these realistic sequences, we simulated extracardiac potentials at epicardial (202 sites) and torso surfaces (352 sites) using boundary element model of the human torso. ECGI in terms of the L-curve was applied to compute epicardial potentials and unipolar electrograms (202 sites). Inversely computed electrograms correlated well with those simulated by an anatomical model (r > 0.9 at 68% of sites). Specifically, ECGI accurately reconstructed the following features that have been observed during measurements on the exposed canine hearts: (a) an epicardial potential pattern with a central minimum and two maxima, with the minimum positioned above the pacing site; (b) a complete transient loss of one of the positive areas in the epicardial potential pattern when the necrosis was located subepicardially; and (c) a transient gap in the expanding positive areas of the epicardial potential pattern when the necrosis was located intramurally or subendocardially. Findings of our study indicate that ECGI provides detailed reconstruction of patterns of myocardial activation in the presence of localized necroses and may be useful in the assessment of arrhythmogenic substrate in the clinical setting.

Animals↗
PubMed1998

Driveway crush injuries in young children: a highly lethal, devastating, and potentially preventable event.

BACKGROUND/PURPOSE: The aim of this study was to investigate driveway-related injuries in children, identify associated risk factors, and evaluate outcome compared with other mechanisms of blunt trauma. METHODS: A 6-year review (1991 to 1996) of pediatric (age less than 18 years) pedestrian injuries treated at two urban trauma centers was conducted: one regional pediatric trauma center and one level I trauma center with pediatric commitment. Five hundred twenty-seven children injured in pedestrian accidents were identified from the trauma registry; 51 children (10%) sustained traumatic injuries as a result of being struck in their driveway. Data are reported as mean +/- SEM. RESULTS: Children less than 5 years of age (n = 41) had an injury severity score (ISS) of 12.3+/-2.3, 15 (37%) sustained closed head injury, 13 (37%) had torso trauma, 19 (46%) skeletal trauma, and eight (20%) died. Children > or = 5 years old (n = 10) had an ISS of 10.7+/-2.4, three (30%) sustained closed head injury, four (40%) torso trauma, six (60%) skeletal trauma, and none died. In contrast, all other pediatric pedestrian accidents analyzed over the same time period had a mortality rate of only 2% (11 of 476). CONCLUSIONS: Pediatric driveway trauma carries a significant risk of head injury and a 10-fold increase in mortality in children under 5 years of age when compared with all other pediatric pedestrian accidents. More emphasis must be placed on injury prevention and public education to prevent this devastating mechanism of injury in these young, vulnerable children.

Accidents, Home↗
PubMed1997

The inverse problem of electrocardiography: a solution in terms of single- and double-layer sources of the epicardial surface.

An approach to the inverse problem of electrocardiography that involves an estimation of the electric potentials (double-layer equivalent sources) on the heart's epicardial surface from the electrocardiographic potentials that are measurable on the body surface has received considerable attention. This report deals with a heretofore unexplored extension of this approach, one that yields, in addition to the electric potentials on the epicardial surface, the normal components of their gradients (single-layer equivalent sources). We show that this formulation has at least three advantages over the formulation in term of epicardial potentials alone: (1) single-layer equivalent sources, which reflect the flow of current across the epicardial surface, are well suited for the imaging of regional ischemia and infarction; (2) the transfer matrix linking the epicardial and body-surface potentials for this formulation is less ill conditioned than that for the formulation in terms of potentials alone; (3) the input vector for inverse calculations consists of spatially filtered (rather that directly measured and therefore noise) body-surface potentials. To establish the feasibility of this new formulation of the inverse problem and to compare it with the formulation in terms of potentials alone, we used a realistically shaped boundary-element model of human torso. By calculating singular values less ill conditioned. We then directly calculated epicardial and body-surface potentials for a single dipole located centrally and for three simultaneously active dipoles located eccentrically in the torso's heart region and used these results to test three methods that are prerequisites of a successful inverse solution: Tikhonov regularization, linearly constrained least squares, and an L-curve method. The feasibility of the new formulation was demonstrated by the fact that the method based on the linearly constrained least squares improved on overregularized Tikhonov solutions over a wide range of regularization parameters, and it yielded solutions that were more accurate than the best-possible Tikhonov solutions. Moreover, the L-curve solution procedure, which requires no a priori information about the solution, yielded slightly underregularized, but accurate, estimates for the optimal regularization parameter and the corresponding best-possible Tikhonov solution. Our results also showed that replacing--in the interest computational economy--quadrature formulas for the planar triangles with various approximate formulas for the nodes of the model reduces the accuracy of the inverse solution.

Electrocardiography↗
PubMed1990

A computerized simulator for critical-care training: new technology for medical education.

A patient simulator has been developed for training, certification, modeling, and demonstrating problems in the management of critical-care patients. The Critical Care & Hemodynamic Monitoring Training System consists of a personal computer, software, and a replica of a human torso designed to enable students to practice critical-care medicine. The computer displays patient histories, laboratory results, treatment options, patient responses, and a real-time cardiac monitor. The torso apparatus is used to practice insertion of a hemodynamic monitoring catheter; the cardiac monitor displays catheter pressure readings as the catheter is advanced into the heart and also pulmonary artery and wedge position. Special screen calculators in the program may be used to determine hemodynamic, respiratory, ventilatory, and renal function indices. In contrast to previously described simulators and computer oriented instructional programs, this system contains no inherent data base. Instead, authors build a library of informative cases by using the hardware and software tools provided. Individual "modules" of patient information are authored, and these are transparently linked as a student undertakes management of a patient. Although this system is a technologic achievement, determination of its usefulness as an instructional tool or certification aid must come from broader use and controlled studies.

Clinical Competence↗
PubMed1995

Postinjury neutrophil priming and activation: an early vulnerable window.

BACKGROUND: Generation of extracellular, cytotoxic superoxide anion (O2-) by polymorphonuclear neutrophils (PMNs) contributes to an unbridled inflammatory response that can precipitate multiple organ failure (MOF). Release of O2- is markedly enhanced when activated PMNs have been previously "primed" by inflammatory mediators, such as those expressed after trauma. We therefore hypothesized that PMN priming occurs as an integral part of the early inflammatory response to trauma. METHODS: PMNs were obtained from 17 high-risk patients with torso trauma at 3, 6, 12, 24, 48, and 72 hours after injury, as well as from 10 healthy donors, and the in vitro release of O2- was quantitated with a kinetic, superoxide dismutase (SOD)-inhibitable cytochrome c reduction assay. PMN O2- release was measured in the presence and absence of 1 mumol/L N-formyl-methionyl-leucyl-phenylalanine (fMLP) and after priming and activation with 20 nmol/L platelet-activating factor (PAF) and 1 mumol/L fMLP, respectively. RESULTS: In vitro PMN O2- release was used to determine whether postinjury PMNs were (1) activated in vivo, (2) primed in vivo, or (3) primable in vitro. Unstimulated PMNs from trauma patients spontaneously expressed modest amounts of O2- in vitro from 6 to 48 hours after injury, suggesting endogenous activation. Also, fMLP-activated PMNs collected between 3 and 24 hours after injury expressed more O2- than controls (p < or = 0.02), indicating in vivo, trauma-related priming. Furthermore, postinjury PMNs were maximally primed in vivo (i.e., in vitro exposure to PAF before fMLP activation failed to significantly enhance O2- release) as compared to PMNs treated with fMLP. CONCLUSIONS: These data indicate that major torso trauma (first hit) primes and activates PMNs within 3 to 6 hours after injury. Consequently, we postulate that postinjury priming of PMNs may create an early vulnerable window during which a second hit (e.g., a secondary operation or delayed hemorrhage) activates exuberant PMN O2- release, rendering the injured patient at high risk for MOF.

Adolescent↗
PubMed1997

Shifts in blood volume alter the perception of posture.

Recent experiments have shown that somatic graviceptors exist in humans. Traditionally, extravestibular gravity information has been thought to originate from mechanoreceptors in the joints, muscles and skin. Experiments with normal, paraplegic and nephrectomized subjects revealed that the kidneys and the cardiovascular system are involved in providing truncal gravity information. The present study intends to determine the influence of shifts in body fluid, especially of the distribution of blood along the subjects' spinal (Z-) axis, on the perception of posture. To this end, the distribution of body fluids was altered by means of the technique of lower body negative and positive pressure (LBNP and LBPP). LBNP leads to venous pooling of blood in the legs, whereas LBPP prevents venous blood from pooling, increasing central volume. Changes in blood distribution were measured by segmental impedance cardiography for four body segments: the upper torso (thoracic cavity), lower torso (abdominal and pelvic region), thigh and calf. Seventeen healthy subjects (mean age: 27.3 years) participated in the experiment. They were positioned on the side (right-ear-down head position) on a tilt table which the subjects and the experimenter could tilt via remote control around an axis parallel to the subjects' visual (X-) axis. The experimenter set the initial tilt in total darkness to arbitrary angles while strictly alternating between head-up and head-down tilts. Subjects were then asked to rotate the board until they felt they were in a horizontal posture. Means and variances of eight pairs of settings were taken as a measure of the subjective horizontal posture (SHP). During LBNP (-30 mmHg), subjects perceived being tilted head-up, whereas LBPP (+30 mmHg) led them to feel tilted head-down. The results corroborate the hypothesis of an effect of the blood's mass on graviception and also indicate supplementary contributions of other visceral afferences.

Adult↗
PubMed1994

The effectiveness of strapping techniques in spinal immobilization.

STUDY OBJECTIVES: To test the effectiveness of strapping techniques in reducing lateral motion of volunteers restrained on a backboard. DESIGN: Randomized block experimentation. SETTING: Medical products research and design laboratory. PARTICIPANTS: Healthy adult volunteers with no history of head, neck, or back trauma. INTERVENTIONS: Subjects were restrained on a wooden backboard using a control and three variations of strapping techniques. The backboard was rolled 90 degrees to the side, and lateral motion of the torso was measured. MEASUREMENTS AND MAIN RESULTS: Nineteen subjects participated. Technique 2, which added an abdominal strap to the control technique, reduced 26% of the lateral motion. CONCLUSION: Additional, specifically placed strapping should be added to the torso to reduce lateral motion on a backboard. Further study is needed to determine the effect of lateral motion in the spine and potential benefits of reduced motion.

Adult↗
PubMed2000

Regressionally determined vertebral inclination angles of the lumbar spine in static lifts.

OBJECTIVE: Our previous study has developed the non-invasive models to predict the vertebral inclination angles by relating the external stick marker angles and radiographic measurements during trunk flexion. Based on these models, the present study attempted to further predict the inclination angles using externally measured body posture (i.e., lumbar posture, trunk flexion angle, knee angle) as well as load handling. DESIGN: Prediction models of the vertebral inclination angles were developed with a stepwise regression technique. This was done by selecting related postural variables as well as load handling as predictors. BACKGROUND: The technique of skin-surface stick marker has been investigated for measuring vertebral inclination angles. This technique, however, is rarely systematically validated by radiographic measurement because of concerns over radiation exposure, especially for ergonomical purposes. METHODS: Twelve healthy men aged 22-31 years were recruited in the experiment. The angles of the vertebral markers and subject's posture were recorded videographically as the subject performed a given task. Prediction models were then developed to express the relationships between the vertebral inclinations and the lifting postures. RESULTS: The prediction models revealed that the lumbar posture (lordosis or kyphosis) had a statistically significant effect on these inclination angles. Non-linear first-order regression models of the torso angle and the pelvic angle were fit to the transformed vertebral inclination angles (transformed from external stick marker angle), with resulting R(2) values between 0. 86 and 0.92. CONCLUSIONS: These findings indicate that the vertebral inclination angles can be calculated easily and with relative accuracy on the basis of the externally measured torso and pelvis angles. RELEVANCE: Measurements of lumbosacral vertebral inclination angles are important in assessing low back stress during lifting. In this study, we used a regression approach to model these angles of the lumbar/sacrum spine in different lumbar postures in the sagittal plane. Our data suggest that the vertebral inclination angles can be calculated easily. These models may be useful to the low back stress evaluation and job design through a biomechanical analysis.

Adult↗
PubMed1999

Three-dimensional kinematics and trunk muscle myoelectric activity in the elderly spine - a database compared to young people.

OBJECTIVE: To establish a database of lumbar spine kinematics and muscle activation profiles for a healthy elderly population. DESIGN: Spine motion parameters and muscle activation profiles of the elderly were identified and quantified in part by comparison with an existing database of younger people. BACKGROUND: Databases are often used as a benchmark to establish what is "normal", or for developing appropriate exercise programs or diagnostic methodologies. METHODS: Twelve people (average age 69 yr) performed full range of motion movements about the flexion, lateral bending and axial twist axes of the lumbar spine. Fourteen torso muscles (7 per side) were monitored with electromyographic electrodes and the signals normalized to maximum voluntary efforts. RESULTS: The elderly were slower moving, and had a reduced range of motion in full flexion and lateral bend but not in axial twist. Furthermore there was more coupled motion evident in the twisting efforts of the elderly. Abdominal muscles appeared to become more active, earlier in the lateral bending movement. CONCLUSIONS: Loss of motion is normal with age together with subtle changes in the way the spine moves and groups of muscles are recruited around the torso. RELEVANCE: Quantification of "normal" changes associated with aging will enable clinicians and scientists to distinguish normal changes from pathology.

Aged↗
PubMed2000

Cervical muscle response during whiplash: evidence of a lengthening muscle contraction.

OBJECTIVE: To assess the potential for cervical muscle injury from a rear-end automobile collision. DESIGN: Experimental design in which human subjects were exposed to low-speed rear-end collisions. The influence of independent variable (gender, speed change, muscle group, and motion phase) on dependent variables (kinematic response, muscle onset and muscle activation level) was examined using repeated-measures analysis of variance. BACKGROUND: Injuries to various tissues of the cervical spine have been proposed, yet little attention has been focused on the cervical muscles as a site of injury. METHODS: 42 subjects (21 males, 20-40 yr) were exposed to collisions of 4 and 8 km/h speed change while measuring kinematic response of the head and torso and electromyography of the sternocleidomastoid and cervical paraspinal muscles. RESULTS: Muscle activation occurred earlier in females and in the 8 km/h speed change. Sternocleidomastoid onset preceded paraspinal onset. Muscle activation level varied significantly with speed change, motion phase and muscle group. Initial rearward retraction of the head relative to the torso resulted in lengthening of the activated sternocleidomastoid, consistent with a contraction-induced muscle injury. CONCLUSIONS: The cervical muscles contract rapidly in response to impact and the potential exists for muscle injury due to lengthening contractions. RELEVANCE: The clinician should recognize the role of cervical retraction in the mechanism of whiplash injury and avoid aggressive motion in that plane during diagnosis and treatment. An understanding of whiplash injury mechanisms should improve patient education and preventative measures.

Accidents, Traffic↗
PubMed1987

Detection of experimental right ventricular infarction by isopotential body surface mapping during sinus rhythm and during ectopic ventricular pacing.

Electrocardiographic (ECG) effects of experimental, isolated right ventricular infarction were studied in 10 dogs during sinus rhythm as well as during ectopic right and left ventricular pacing. Infarction was produced by injecting latex into the right coronary artery and ECG consequences were examined by body surface isopotential mapping methods using an 84 electrode torso array. During sinus rhythm, subtraction of preinfarction from postinfarction maps demonstrated that right ventricular necrosis produced abnormal negative potentials over the right hemithorax during the early, middle and late portions of the QRS complex. These patterns corresponded to loss of R waves and deepening of preexistent or development of new Q and S waves in waveforms from this region. Patterns during ectopic ventricular stimulation were compared with mean maps derived from 13 control dogs. Both left and right ventricular pacing after right ventricular infarction resulted in a right-sided abnormal minimum, similar in location to that observed during sinus rhythm, throughout the QRS complex. Thus, right ventricular necrosis does produce QRS complex changes over the right torso that are analogous to those produced by left ventricular infarction, and the dominant pattern of an abnormal right-sided minimum was present regardless of the ventricular activation pattern. This latter finding suggests that the region of right ventricular necrosis provided a supplementary path for current to reenter the heart regardless of the current source, so that an overlying electrode would record negative voltage with all activation patterns.

Animals↗
PubMed1996

Long-term femoral vein central venous access in cancer patients.

Subclavian percutaneous access with reservoir placement has been shown to be difficult or contraindicated in some patients. Of 465 cancer patients who required a port placement between January 1992 to January 1995, 41 (8.8%) had alternative percutaneous femoral access with a totally implantable port reservoir located in the abdomen because of the inaccessibility to subclavian or jugular veins and/or the presence of massive cutaneous metastases or severe radiodermitis in the upper part of the torso. Overall implant days was 9880, with an average of 241 days (range: 65-445). Ports were alternatively used for chemotherapy and nutritional purposes in 11 of 41 patients. Late morbidity causing the removal of the implanted ports was observed in two of 41 (4.9%) and 25 of 424 (5.9%) patients in the femoral and subclavian series, respectively (P = 0.86). The femoral percutaneous access for totally implantable port devices appears to be a safe alternative for cancer patients when subclavian and/or jugular vein catheterization and reservoir in the upper part of the torso is contraindicated.

Adult↗
PubMed2003

Determinations of prostate volume at 3-Tesla using an external phased array coil: comparison to pathologic specimens.

RATIONALE AND OBJECTIVES: To compare techniques for measuring in vivo prostate volumes using torso phased-array imaging at 3-Tesla. METHODS: Eleven patients imaged at 3-Tesla with a torso-phased array coil using multiplanar fast spin echo (FSE) T2-weighted imaging who underwent radical prostatectomy comprised the study population. Surgical specimens were imaged. The pathologic specimen volume was compared with varieties of magnetic resonance volume determinations, the latter using ellipsoid and planimetric assessments. Three-dimensional images of the excised prostate were generated. Linear correlation coefficients were calculated comparing volume determinations from image data and pathologic data. RESULTS: Correlation coefficient (r2) values from the ellipsoid formula among six different data sets ranging between 0.325 to 0.751; the highest in vivo r2 value was obtained by multiplying the anterior-posterior and the superior-inferior dimensions from the sagittal image by the right-left dimension from the axial image. The r2 values of the planimetric volume and specimen 3-dimensional volume rendering were 0.652 and 0.86, respectively. CONCLUSIONS: Surface coil prostate imaging at 3-Tesla provides undistorted images for volume assessment and in vivo volume determinations very close to ex vivo imaging volume determinations.

Adenocarcinoma↗
PubMed2000

The Drosophila SHC adaptor protein is required for signaling by a subset of receptor tyrosine kinases.

Receptor tyrosine kinases (RTKs) transduce signals via cytoplasmic adaptor proteins to downstream signaling components. We have identified loss-of-function mutations in dshc, the Drosophila homolog of the mammalian adaptor protein SHC. A point mutation in the phosphotyrosine binding (PTB) domain completely abolishes DSHC function and provides in vivo evidence for the function of PTB domains. Unlike other adaptor proteins, DSHC is involved in signaling by only a subset of RTKs: dshc mutants show defects in Torso and DER but not Sevenless signaling, which is confirmed by epistasis experiments. We show by double-mutant analysis that the adaptors DOS, DRK, and DSHC act in parallel to transduce the Torso signal. Our results suggest that DSHC confers specificity to receptor signaling.

Adaptor Proteins, Signal Transducing↗
PubMed2001

Wheelchair integrated occupant restraints: feasibility in frontal impact.

Individuals often use their wheelchair as a motor vehicle seat when traveling in motor vehicles. The current use of fixed vehicle-mounted wheelchair occupant restraint systems (FWORSs) often results in poor belt fit and discomfort. Additionally, satisfaction, usability and usage rate of FWORSs during transit use are often low. The automotive industry has shown improved occupant restraint usage, belt fit and injury protection when integrating the upper torso and pelvic restraint in a motor vehicle seat. This study compared occupant injury measures of a FWORS to a concept wheelchair integrated restraint system (WIRS) using a 20g frontal sled impact test with a 30 mph change in velocity. Neck loads, neck moments, head, pelvis and chest acceleration, sternum compression and knee and head excursion data were recorded from the wheelchair seated 50th percentile male hybrid III anthropomorphic test dummy (ATD). The WIRS resulted in a lower head injury criteria (HIC) value, lower sternum compression and a lower upper-torso restraint load than the FWORS. Compared with the FWORS, increased head, knee and wheelchair excursions and higher neck loads and moments were measured in the WIRS test. Both restraint scenario injury parameters were complied with occupant injury criteria based on General Motors Injury Assessment Reference Values (GM-IARVs) and occupant kinematic requirements defined by the Society of Automotive Engineers (SAE) voluntary standard, J2249. A higher motion criteria index was calculated for the WIRS scenario and a comparable combined injury criteria index was calculated for both restraint scenarios. The sled impact test showed WIRS concept feasibility, facilitating further development by industrial manufacturers who might further want to pursue this restraint principle to increase wheelchair occupant safety and comfort during transport in motor vehicles.

Accidents, Traffic↗