Significant Difference In Force Research Articles

Assessment of Competency During Orotracheal Intubation in Medical Simulation

Background Clinicians performing orotracheal intubation need to be competent to perform this technical skill safely. It is recognized that aggressive force applied during direct laryngoscopy may damage the oropharyngeal soft tissue; however, force is seldom considered in assessment of competency. The objective of this study was to explore the force applied during orotracheal intubation as a method of further discriminating between levels of competence. We sought evidence of construct validity in the form of discriminant, criterion, and concurrent validity. We hypothesized that the force generated during simulated intubation could serve to discriminate skill level among clinicians. Methods A convenience sample of 35 health-care professionals filled a self-reported questionnaire and were then divided into the following three groups: Group 1, experts (n=16); Group 2, intermediates (n=7); and Group 3, novices (n=12). They then intubated a part-task trainer (Laerdal Airway Management Trainer) after reviewing a procedural video and engaging in one practice session. Intubations were recorded. Outcome measures were as follows: (i) force applied to the epiglottis, calculated (in newtons) using two superimposed pressure-sensitive films (Prescale; Fujifilm, Madison, WI, USA) on the laryngoscope blade; (ii) number of attempts required to achieve successful intubation; (iii) time to intubation; and (iv) hand position. Results Of the four outcome measures, only force applied during orotracheal intubation was able to discriminate between groups. All data are reported as the mean (sd). There was a significant difference in force between groups during orotracheal intubation [one-way anova; experts, 102 (25) N; intermediates, 134 (28) N; and novices, 153 (43) N], with a significant difference (P Conclusions Force exerted during intubation provides meaningful information when attempting to discriminate intubation skill level. Force demonstrated criterion validity and could be used as a measure of competency during training.

Prospective Evaluation of Innovative Force Assessing Firmware in Simulation to Improve the Technical Competence of Surgical Trainees.

Suturing is an integral part of all surgeries. In minimal access surgery, the force exerted is based only on visual perception (tautness of the thread and degree of tissue deformation). An unbalanced suture force can cause tissue rupture or cut-through resulting in avoidable morbidity and mortality. There is a need to find ways of improving surgical dexterity and finesse without adversely affecting patient outcomes. We aimed to calculate the knot-tying force in minimal access pancreatic surgery (MAPS) performed by experienced surgeons (ES) and use this information to develop a surgical suturing model to train the surgical trainees. We have developed a firmware for force sensor calibration and post-data analysis, using which we aimed to compare the differences in forces applied by a trainee as compared to ES. Our technology showed that, as compared to the ES, the trainee's (TS) knot was unbalanced with significant differences in force applied per knot for each of the knots (P < 0.01). The shape of the Force curve for each suture was also different for the TS as compared to the ES. After using the training tool, the forces applied by the TS and the Force curve for the whole suture were similar to those of the ES. Our firmware promises to be an excellent training tool for organ anastomosis. Considering the complexity and likely complications of MAPS, it is a sine qua non that the surgeon be highly experienced and skilled. Surgical simulation is attractive because it avoids the use of patients for skills practice and provides relevant technical training for trainees before they can safely operate on humans.

Assessment of competency during orotracheal intubation in medical simulation

Clinicians performing orotracheal intubation need to be competent to perform this technical skill safely. It is recognized that aggressive force applied during direct laryngoscopy may damage the oropharyngeal soft tissue; however, force is seldom considered in assessment of competency. The objective of this study was to explore the force applied during orotracheal intubation as a method of further discriminating between levels of competence. We sought evidence of construct validity in the form of discriminant, criterion, and concurrent validity. We hypothesized that the force generated during simulated intubation could serve to discriminate skill level among clinicians. A convenience sample of 35 health-care professionals filled a self-reported questionnaire and were then divided into the following three groups: Group 1, experts (n=16); Group 2, intermediates (n=7); and Group 3, novices (n=12). They then intubated a part-task trainer (Laerdal Airway Management Trainer) after reviewing a procedural video and engaging in one practice session. Intubations were recorded. Outcome measures were as follows: (i) force applied to the epiglottis, calculated (in newtons) using two superimposed pressure-sensitive films (Prescale; Fujifilm, Madison, WI, USA) on the laryngoscope blade; (ii) number of attempts required to achieve successful intubation; (iii) time to intubation; and (iv) hand position. Of the four outcome measures, only force applied during orotracheal intubation was able to discriminate between groups. All data are reported as the mean (sd). There was a significant difference in force between groups during orotracheal intubation [one-way anova; experts, 102 (25) N; intermediates, 134 (28) N; and novices, 153 (43) N], with a significant difference (P<0.05) noted between novice and experts on post hoc analysis. Force exerted during intubation provides meaningful information when attempting to discriminate intubation skill level. Force demonstrated criterion validity and could be used as a measure of competency during training.

A note on the force of whip impacts delivered by jockeys using forehand and backhand strikes

The Australian Racing Board makes a distinction under its Rules of Racing concerning whip use between forehand and backhand whip action that is critically important: before the final 100 m of a race, the whip shall be used in a forehand manner neither in consecutive strides nor on more than 5 occasions. This seems to imply that backhand whip use is less closely scrutinized, which may have profound implications for horse welfare. We used pressure-detection pads to examine the force on the impact of 288 whip strikes (left forehand, left backhand, right forehand, and right backhand; n = 72 each) in batches of 12 consecutive strikes by 6 right-handed jockeys based in Victoria, a state in which thoroughbred racing is always conducted in a counterclockwise direction. The mean latency (±standard error of the mean) to complete each series of 12 strikes was 6.89 ± 0.44 seconds. The mean for force was 46.90 ± 5.39 N. Significant differences in force emerged between individual jockeys and in most interactions between jockey, hand and action. This highlights the problems the industry has in trying to enforce equity in whip use to satisfy punters while at the same time giving reassurances about horse welfare. The current results show that action (forehand vs. backhand) does not influence force on impact when using the nondominant hand. However, when using the dominant hand, these jockeys struck with more force in the backhand (P = 0.02). This result challenges the current focus on welfare concerns around forehand whip strikes. It should inform any review of the rules around whip use because it may help to avoid any unjustified focus on either forehand whip use or backhand whip use. This would help to inform the debate around levels of impact on fatigued horses when they are being struck for a perceived sporting gain.

Does the “bumper” created during Bankart repair contribute to shoulder stability?

The aim of this study was to determine the optimal repair configuration for anterior shoulder instability after a labral tear. Nine fresh, frozen shoulders were used. With a 50-N axial force, the humeral head was translated anteriorly, and the translational force was measured. The measurement was performed with the capsule intact, after creating a Bankart lesion, and after the Bankart repair at 5 different positions: glenoid rim, glenoid surface-2 mm (on the glenoid surface 2 mm from the glenoid rim), glenoid surface-5 mm, scapular neck-2 mm (on the scapular neck 2 mm from the glenoid rim), and scapular neck-5 mm. Glenoid rim fixation was done with and without a "bumper." The "bumper" was created by plicating the capsule to form a thickened mass of tissue. The translational force was restored to the intact level after the glenoid rim fixation. However, there was no significant difference in force after the Bankart repair with and without a "bumper" nor after the glenoid rim fixation and glenoid surface-2 mm. The force significantly decreased after scapular neck-2 mm and scapular neck-5 mm compared with the glenoid rim fixation. The anchor fixation on the glenoid face does not increase the translational force compared with the glenoid rim placement, but the placement on the scapular neck decreases the translational force.

Mechanical properties of beta-titanium wires

To evaluate the force-deflection behavior of six beta-titanium wires using a three-point bending test. The wires timolium (TIM), titanium molybdenum (ORG), beta titanium (BETA), resolve (RES), titanium molybdenum alloy (TMA), and TMA low friction (TMAL) were adapted into two stainless steel brackets, with no angulation or torque. Both brackets were bonded to an acrylic jig with a 10-mm interbracket distance. A testing machine (Instron) applied deflections of 0.2 to 2.0 mm. Force-deflection diagrams were determined from a passive position to an activation of 2 mm and then during deactivation. Forces of activation and deactivation at a deflection of 1 mm were compared by analysis of variance. Results demonstrated that significant differences (P < .05) in force were observed among wires. During activation, forces for the wires were ranked from lowest to highest as TMAL = TMA = RES<ORG = BETA<TIM. During deactivation, forces for the wires were ranked from lowest to highest as TIM<ORG = BETA<RES = TMA<TMAL. The wires exhibited similar activation-deactivation diagrams. This study revealed significant differences in force during activation and deactivation among the six types of beta-titanium wires tested.

Myonuclear Domain Size and 3d Myonuclear Organization in Single Muscle Fibers from Myostatin Deficient Or IGF1 Overexpressing Mice

Myostatin deprived or IGF-1 over-expressing mice are characterized by a 2-3 fold increase in muscle size compared to controls. Despite the hypertrophy these mice show significant difference in force generating capacity, i.e., maximum force normalized to muscle fiber cross-sectional area or specific force. That is, specific tension in IGF1 overexpressing transgenic mice is similar to controls while significantly lower in the myostatin knock out mice. The mechanism underlying this compromised muscle function is unknown. In an attempt to explore this mechanism we have investigated the size of cytoplasmic volume (myonuclear domain MND) supported by individual myonuclei in single muscle fiber segments from myostatin deficient, IGF1 over-expressing and control mice, using a novel algorithm to measure the MND in 3D. Single skinned muscle fiber segments were mounted at fixed sarcomere length corresponding to optimum filament overlap for force generation and stained with DAPI (myonuclei) and rhodamine (actin). Our image analysis algorithm was highly effective in determining the spatial organization of myonuclei and distribution of MNDs along the length of the fiber. Early results point towards an inverse relationship between MND and specific force. This implies that hypertrophy is primarily due to expansion of existing MNDs in myostatin knock-outs, and addition of more myonuclei in IGF1 over-expressing mice. This is suggested to have significant effects on transcriptional control of protein synthesis/degradation, turnover rates and/or posttranslational modifications of contractile proteins. We conclude that a maintained MND size is a prerequisite for force generation capacity in hypertrophied muscle fibers.

Temporary stay at various environmental humidities affects attachment ability of Colorado potato beetles Leptinotarsa decemlineata (Coleoptera, Chrysomelidae)

In a natural environment, insects live in different microhabitats varying in their humidity. Because insect adhesive mechanism at least partly relies on the capillary force, it is natural to assume that environmental humidity may considerably influence insect attachment. However, this aspect has been neglected in the literature so far. We present the first experimental study demonstrating the influence of the exposure to moist surfaces on the attachment of Colorado potato beetles Leptinotarsa decemlineata. Male beetles were kept at either a dry or moist condition with varying duration of stay for a period up to 160 min. Using centrifugal force tester, their friction forces were then measured on a plexiglas surface. The results show significant differences in force depending on the kind of pre-conditioning. A temporary stay in dry environment had no significant impact on the generated friction forces within the tested time scale. After walking on moist filter paper, forces increased significantly up to 171% of the initial forces measured after 1 min of preconditioning. These results show that insects of the same species may be strongly influenced in their attachment by environmental conditions. The second important conclusion is that results of different experimental studies on insect attachment can hardly be compared if they were performed under different environmental conditions.

P.2.016 A possible involvement of opioid degrading enzymes in individual reactivity to acute traumatic stress

The Australian Racing Board makes a distinction under its Rules of Racing concerning whip use between forehand and backhand whip action that is critically important: before the final 100 m of a race, the whip shall be used in a forehand manner neither in consecutive strides nor on more than 5 occasions. This seems to imply that backhand whip use is less closely scrutinized, which may have profound implications for horse welfare. We used pressure-detection pads to examine the force on the impact of 288 whip strikes (left forehand, left backhand, right forehand, and right backhand; n = 72 each) in batches of 12 consecutive strikes by 6 right-handed jockeys based in Victoria, a state in which thoroughbred racing is always conducted in a counterclockwise direction. The mean latency (±standard error of the mean) to complete each series of 12 strikes was 6.89 ± 0.44 seconds. The mean for force was 46.90 ± 5.39 N. Significant differences in force emerged between individual jockeys and in most interactions between jockey, hand and action. This highlights the problems the industry has in trying to enforce equity in whip use to satisfy punters while at the same time giving reassurances about horse welfare. The current results show that action (forehand vs. backhand) does not influence force on impact when using the nondominant hand. However, when using the dominant hand, these jockeys struck with more force in the backhand (P = 0.02). This result challenges the current focus on welfare concerns around forehand whip strikes. It should inform any review of the rules around whip use because it may help to avoid any unjustified focus on either forehand whip use or backhand whip use. This would help to inform the debate around levels of impact on fatigued horses when they are being struck for a perceived sporting gain.

Characterization of Forces on the Sternal Midline Following Median Sternotomy in a Porcine Model

The development of more effective fixation devices for reapproximating and immobilizing the sternum after open-heart surgery is limited by current methods for evaluating these devices. In particular, precise emulation of in vivo sternal loading has not been achieved in controlled model systems. The present study is an initial effort to determine the in vivo loading parameters needed to improve current in vitro and in silico (computational) models. Towards this goal, the direction, magnitude, and distribution of loading along a midline sternotomy were characterized in a porcine model. Two instrumented plating systems were used to measure the forces across the bisected sternum in four anaesthetized Yorkshire pigs during spontaneous breathing, ventilated breathing, and coughing for four treatments: live, cadaveric, embalmed, and refrigerated. Changes in forces incurred by death and embalming were also investigated to evaluate the potential applicability of cadavers as models for testing sternal fixation devices. The magnitudes of the respiratory forces in three orthogonal directions ranged from 0.4 N to 43.8 N, many fold smaller than previously estimated. Dynamic forces were highest in the lateral direction during coughing and low in all directions during normal breathing. No significant differences in force were found between the four treatments, most likely due to the unexpectedly low magnitude of forces in all groups. These results provide the first measurements of in vivo sternal forces and indicate that small cyclic fatigue loads rather than large quasistatic loads should be applied in future model systems to best evaluate the mechanical performance of fixation devices.

The Environmental Influence of Light Coke™, Phosphoric Acid, and Citric Acid on Elastomeric Chains

The purpose of this study was to evaluate the in vitro effect of Light Coke, phosphoric acid, and citric acid on the force decline pattern of two types of elastomeric chains. One hundred sixty gray colored elastomeric chain modules, 80 Chainette (GAC) and 80 Sunburst (GAC) chains, were divided into four groups for immersion into Light Coke, phosphoric acid, citric acid, and artificial saliva. The initial stretched force of the elastomeric chains ranged from 220 gf to 250 gf. During the experiment, all elastomeric chains were kept immersed in artificial saliva at 37 masculineC (pH 6.24) to simulate the oral environment. To simulate daily consumption of Light Coke, the elastomeric chains were immersed in the solutions twice a day for 15 minutes. The control group was kept immersed in artificial saliva continuously with no further treatment. Force (gf) was measured with a Dial-Type dynamometer (Dentaurum), initially (baseline), 24 hours, 7, 14, and 21 days. Data were analyzed using the Tukey test at a 5% level of probability. A statistically significant reduction on the force produced by the elastomeric chains was seen at different time points. The greatest reduction in force occurred in the first 24 hours (p=0.01). Force decay of the Chainette elastomeric chains were lower than the Sunburst (p<0.05). The immersion treatments caused no statistically significant difference in force for either chain module (p>0.05). Good elastomeric chain properties are necessary for effective tooth movement, and knowledge of force-decay rates is an important factor in achieving the best orthodontic outcome.

Bite force and handgrip force in patients with molecular diagnosis of myotonic dystrophy

Myotonic dystrophy is a multisystemic disease with varying symptomatology. The aim of this study was to compare the maximal bite force and handgrip force in patients with molecular diagnosis of myotonic dystrophy with those in a group of healthy individuals. It was hypothesized that these forces were reduced in the patients in comparison with the control subjects. The bite and handgrip forces of 37 patients with molecular diagnosis of myotonic dystrophy and 37 control subjects matched regarding age and gender were measured using an electronic dynamometer. The bite and handgrip forces were significantly lower in the myotonic dystrophy patient group when compared with the healthy controls (P < 0.0001). There were no significant force differences between genders, right- or left-hand side of mastication or hands in the myotonic dystrophy patient group whereas such differences were found among the controls. There were moderate but significant correlations between bite and handgrip force in both groups (r = 0.43-0.59; P < 0.01). It was concluded that there were considerable differences between the myotonic dystrophy group and the control subjects regarding both bite force and handgrip force. The weakness of the masticatory and hand muscles may have various negative consequences for oral function and dental health in patients with myotonic dystrophy.

Failure Properties of Cervical Spinal Ligaments Under Fast Strain Rate Deformations

The failure responses of the anterior longitudinal ligament, posterior longitudinal ligament, and ligamentum flavum were examined in vitro under large strain-rate mechanical loading. To quantify the failure properties for 3 cervical spinal ligaments at strain rates associated with traumatic events. There exists little experimentation literature for fast-rate loading of the cervical spine ligaments. The small amount of available information is framed only in extensive experimental coordinates, and not in the context of strains. Bone-ligament-bone complexes were strained at fast rates, in an incrementally increasing loading protocol using a servohydraulic mechanical test frame. Failure loads and displacements were converted to engineering and true stress and strain values, and compared for the different ligaments (anterior longitudinal ligament, posterior longitudinal ligament, and ligamentum flavum), spinal levels (C3-C4, C5-C6, and C7-T1), and for male versus female specimens. There were no significant differences in force or true stress for gender or spinal level. There was a significant difference in force and true stress for ligament type. A difference was found between the posterior longitudinal ligament and ligamentum flavum for failure force, and between the ligamentum flavum and both the anterior and posterior longitudinal ligaments for failure true stress. No significant differences were found in true strain for ligament, gender, or spinal level. The mean ligament failure true strain was 0.81. Failure true strains were approximately 57% of the failure engineering strains. Once the injury mechanisms of the cervical spine are fully understood, computational models can be employed to understand the potentially traumatic effects of clinical procedures, and mitigate injury in impact, falls, and other high-rate scenarios. The soft tissue failure properties in this study can be used to develop failure tolerances in fast-rate loading scenarios. Failure properties of the anterior and posterior longitudinal ligaments were similar, and the same properties can be used to model both ligaments.

Evaluation of Extraction Force for Wooden Guy Anchors

Wooden stakes are used to anchor guy lines on many newly transplanted trees. It has been recommended that the angle of the stake be either in-line with the guy (45 degrees toward the tree) or at right angles to the guy (45 degrees from horizontal away from the tree). This trial was conducted to determine which, if either, of these directions will provide the maximum amount of resistance to extraction. Stakes were driven into the soil at two angles and vertically into the soil then were extracted using a measured force. There was no significant difference in force required to extract the stakes driven in-line with the guy or at a right angle to it. There was a significant difference (p &lt;. 05) between angled stakes and those driven straight into the soil. The force required for extraction of the stake driven vertically was more than twice that of the angle-driven stakes. It was hypothesized that the differences in extraction force were due to soil disruption that occurs when driving stakes into the soil. For maximum strength, it is recommended that wooden stakes be driven vertically into the soil.

Practice and knowledge of cricoid pressure in southern Sweden.

For 40 years cricoid pressure has been used to prevent regurgitation of gastric contents during induction of anaesthesia. Recent studies have emphasised use of more moderate force so as not to deteriorate ventilation or endotracheal intubation. This study was undertaken to assess the current practice and knowledge of cricoid pressure among anaesthesia personnel in southern Sweden. Forty-eight subjects at two anaesthetic departments in southern Sweden were asked to apply and maintain cricoid pressure for 60 s with their dominant and non-dominant hands, respectively, in a laryngotracheal model during simulated intravenous induction of anaesthesia. Where and how pressure was applied as well as the force used by each subject was recorded together with information on individual experience and knowledge of the technique. There were no significant changes in force applied over time, and no significant differences in force between dominant (median 36 N; 25th percentile 26 N; 75th percentile 50 N) and non-dominant (37; 26; 50 N) hand, between female and male subjects or between physicians, nurses and assistant nurses. Force exceeding 60 N was recorded at least once in 21% of subjects. More than two-thirds (69%) had not heard of any recommended level of force to be applied. Forty percent of anaesthesiologists were unaware of any contraindications. More specific education and training seems mandatory to improve clinical use of cricoid pressure and possibly increase patient safety. Simulators allowing cricoid pressure to be carried out and evaluated in a standardised manner should therefore be incorporated into future training programmes and airway management courses.

Force generation capacity of knee extensor muscles in speed skaters.

The force generation capacities during a single as well as repetitive maximal knee extensions were investigated in speed skaters in relation to the cross-sectional area (CSA) of quadriceps femoris muscles. The subjects were 15 male and 12 female speed skaters, and an age-matched untrained group (20 men and 21 women). An isokinetic dynamometer was used to determine force output at three constant velocities of 1.05, 3.14 and 5.24 rad.s-1 and to perform 50 repetitive maximal contractions at 3.14 rad.s-1. The CSA was measured by using a B-mode ultrasound technique at the midpoint of the thigh length. The isokinetic force produced at each test velocity was significantly correlated to CSA in all the subjects (r = 0.867-0.920, P < 0.05). There was no significant difference in force (F) per unit CSA (F.CSA-1) at the three test velocities between the speed skaters and untrained subjects within the same sex. In both the speed skaters and untrained subjects, the women showed significantly lower F.CSA-1 at 3.14 and 5.24 rad.s-1 than the men. The means of force output (F) of every five consecutive and all trials during the repetitive maximal bout were significantly correlated to CSA in all the subjects (r = 0.889-0.934, P < 0.05). Compared to the untrained subjects, the speed skaters showed significantly higher F for every five consecutive contractions even when calculated per unit of CSA (F.CSA-1), and had lower percentage of decline of F during a trial span between the 6th-10th and 41st-45th trials. For the untrained subjects, F.CSA-1 for every five consecutive contractions was significantly lower in the women than in the men. For the speed skaters, the men showed significantly higher F.CSA-1 than the women during a trial span from the 1st-5th trial to the 31st-35th trial, although there was no significant sex difference in the ratio on and after the 36th-40th trial. From these results, it is concluded that the speed skaters show a higher muscle performance in a repetitive maximal contraction task rather than in a single contraction compared to the untrained subjects. In addition, judging from the results for the speed skaters, the women might be less trainable than the men in the F.CSA-1 during a single contraction at a fast velocity as well as repetitive maximal contractions.

Biomechanical analysis of two change-of-direction maneuvers while running.

Many research efforts focus on unidirectional gait. However, few functional activities are exclusively linear: people regularly change directions to evade obstructions. Directional changes have been identified as particularly hazardous, but rarely studied. The purpose of this study was to examine the kinetics of abrupt changes of direction while running. Twelve adult volunteers performed 10 trials each for 45 degrees and 90 degrees change-of-direction conditions. Orthogonal force and moment (torque) records were obtained using a computer-interfaced force platform system. Vertical, braking, and propulsive force and applied torque variables were extracted for statistical analysis. Significant force differences (p < .01) were identified between conditions. Applied torques were highly variable and not significantly different. Functionally, these data suggest that applied forces serve as the principal impetus of directional change.

A comparative in vitro study of fixation of mandibular fractures with paraskeletal clamps or screw plates

The use of porcine rib pairs as an in vitro analog for the edentulous mandible is described. Using this model, the relative degree of fixation achieved with a screw plate (Champy) and a paraskeletal clamp plate (Mennen) has been evaluated. The fractured plated ribs failed at significantly lower bending forces than the non-sectioned controls. However, no statistically significant difference in force at failure between the two different methods of plate fixation could be demonstrated.

Control of myofibrillar ATPase activity and force in myodystrophic muscle.

Myofibrillar ATPase activity was measured as a function of the free calcium concentration in skeletal muscles of control and myodystrophic mice. In addition, the force developed in skinned extensor digitorum longus (EDL) fibers of control and myodystrophic mice was measured as a function of the free calcium concentration, and a histomorphometric study was performed on soleus and EDL muscles of control and myodystrophic mice. The results showed that the myofibrillar ATPase activity and the force-generating mechanisms of control and myodystrophic muscles were controlled to the same relative degree by equivalent concentrations of calcium ions. Upon maximal activation of the ATPase activities, we measured 18% less activity in myodystrophic muscles than in control muscles. Maximal activation of the force-generating capacity in skinned fibers showed there was no significant difference in force produced in the control compared to myodystrophic fibers. The histomorphometric study revealed no alteration in the relative distribution of different fiber types in myodystrophic compared to control muscles. However, the histomorphometry did reveal a larger slow (type 1) relative cellular area compared to total cross-sectional area in myodystrophic muscle than in controls. We propose that the lower ATPase activity but equal force-generating capacity of myodystrophic muscles compared to control muscles is due to myodystrophic muscles being composed of a greater fraction of myofibrils from slow (type 1) fibers than control muscles.