Compression Brace Research Articles

Outcomes Following Dynamic Compression Bracing for Pectus Carinatum.

Introduction: Children with pectus carinatum (PC) are particularly vulnerable to psychosocial effects of poor body image, even though they may not experience physical symptoms. Nonoperative treatment with orthotic bracing is effective in PC correction. We describe our experience with dynamic compression bracing (DCB) for PC patients and their satisfaction with bracing. Materials and Methods: Prospective institutional data of patients undergoing DCB from July 2011 to June 2018 were reviewed and analyzed for those who entered the retainer mode after correction, defined by a correction pressure of <1 psi. A telephone survey was conducted regarding their bracing experience and satisfaction with the outcome on a scale of 1-10. Results: Of 460 PC patients, 144 reached the retainer mode. Median time to retainer mode was 5.5 months. There was no statistically significant relationship between initial correction pressure or carinatum height and time to retainer mode (P = .08 and P = .10, respectively). Fifty-seven percent were compliant with brace use, and median time to retainer mode in this subset was significantly shorter than noncompliant patients (3.5 months versus 10 months, P < .001). Fifty-three percent responded to the survey 13 months [interquartile ratios 3, 33] after the last clinic visit. The main barrier to compliance with wearing the brace was discomfort (37%), while the main motivation for compliance was appearance (58%). All endorsed bracing as worthwhile, with 94% reporting a satisfaction rating of 8 or greater for the correction outcome. Conclusion: DCB is effective in achieving correction of PC in compliant patients. Regardless of time to retainer mode, patients reported high satisfaction with bracing.

Sensorized Orthosis for Non-Operative Treatment of $Pectus~Carinatum$ in Pediatric Patients

This paper describes a sensorized orthosis used to objectively monitor the follow-up of pediatric patients affected by Pectus Carinatum and treated through compression therapy. The study reports an analysis made on 25 patients. The pressure exerted by the compression brace was monitored by means of a high-density sensing matrix at every outpatient check, over 150 days. The pressure maps derived from this analysis correlated with the clinical parameters indicating a successful outcome for the treatment of specific deformity types such as symmetric chondrogladiolous and rib flares. Results demonstrate that bracing is an effective tool in well-motivated patients in the previously mentioned deformity types. Pressure mapping emerged as a parameter to objectively assess treatment efficacy and may pave the way to a new generation of orthoses with high-density sensorized elements chronically embedded in their structure.

Effectiveness of Compressive External Bracing in Patients with Flexible Pectus Carinatum Deformity: A Review.

There has been a growing interest in the nonoperative treatment of chest wall deformities over the last few decades; with the advent of external compressive orthotics, similar outcomes have been reported compared with surgical intervention. There have been fewer major complications reported with dynamic compression bracing on the chest wall; however, the Achilles heel of this approach still lies with treatment tolerability and compliance. A Medline literature search was undertaken to evaluate the evidence concerning the techniques, modifications, and outcomes associated with external compressive bracing in the setting of pectus carinatum. Sixteen articles were integrated after literature review and data were collected on methods of assessing pectus carinatum (degree of severity as well as type), patient selection protocol (i.e., suitability for external compressive bracing), the bracing protocol itself, duration of treatment, metrics used to assess outcome, and success, compliance, and dropout rate, and length of long-term follow-up. Compressive external bracing appears to be a safe and well tolerated nonsurgical treatment option for young patients with flexible pectus carinatum deformities. However, there is still a need for robust level I randomized data from multiple centers with a clearly standardized bracing protocol, objective measurement of outcomes, and recording of results at the end of the bracing treatment program in sufficiently powered sample sizes over a significant follow-up period.

Experimental Study on Hysteretic Behavior of the Overlapped K-Joints with Concrete Filled in Chord

Due to the insufficient radial stiffness of the steel tube, the cracking of the weld and the plastic deformation of the string often occur under the cyclic loading of the hollow section pipe joint. In order to avoid such a failure, the overlapped K-joints were strengthened by pouring different concrete into the chords. Furthermore, to explore the detailed effect of filling different concrete in a chord on the hysteretic behavior of the overlapped K-joints, six full-scale specimens were fabricated by two forms, which included the circular chord and braces, the square chord and circular braces, and the low cyclic loading tests, which were carried out. The failure modes, hysteretic curves and skeleton curves of the joints were obtained, and the bearing capacity, ductility and energy dissipation of the joints were evaluated quantitatively. The results showed that plastic failure occurs on the surface of the chord of the joints without filling concrete, while the failure mode of the joints filled with concrete in the chords was the tensile failure of the chords at the weld of the brace toe, and the compressive braces had a certain buckling deformation; The strengthening measures of concrete filled with chord can effectively improve the mechanical properties of the K-joints, the delay of the plastic deformation of the chord, and improve the bearing capacity of the K-joints. Contrarily, the ductility coefficient and the energy dissipation ratio of K-joints decreased with the concrete filled in the chord. The hysteretic behavior of the K-joints with a circular chord and brace was slightly better than that of the K-joints with a square chord and circular brace, and the hysteretic behavior of the K-joints strengthened with fly ash concrete, which was better than that of the K-joints strengthened with ordinary concrete. The results of ANSYS (a large general finite element analysis software developed by ANSYS Company in the United States) analysis agreed well with the experimental results.

Use of an Optical Scanning Device to Monitor the Progress of Noninvasive Treatments for Chest Wall Deformity: A Pilot Study.

BackgroundThe nonsurgical treatment of chest wall deformity by a vacuum bell or external brace is gradual, with correction taking place over months. Monitoring the progress of nonsurgical treatment of chest wall deformity has relied on the ancient methods of measuring the depth of the excavatum and the protrusion of the carinatum. Patients, who are often adolescent, may become discouraged and abandon treatment.MethodsOptical scanning was utilized before and after the intervention to assess the effectiveness of treatment. The device measured the change in chest shape at each visit. In this pilot study, patients were included if they were willing to undergo scanning before and after treatment. Both surgical and nonsurgical treatment results were assessed.ResultsScanning was successful in 7 patients. Optical scanning allowed a visually clear, precise assessment of treatment, whether by operation, vacuum bell (for pectus excavatum), or external compression brace (for pectus carinatum). Millimeter-scale differences were identified and presented graphically to patients and families.ConclusionOptical scanning with the digital subtraction of images obtained months apart allows a comparison of chest shape before and after treatment. For nonsurgical, gradual methods, this allows the patient to more easily appreciate progress. We speculate that this will increase adherence to these methods in adolescent patients.

Improving Behavior of Reinforced Concrete Frames to Resist Progressive Collapse through Steel Bracings

External installation of steel braces has been proved an effective seismic strengthening or retrofitting scheme to upgrade the lateral load-resisting capacity of reinforced concrete (RC) frames. However, the effectiveness of steel bracing in improving the progressive collapse resistance potential of RC frames is vague. To fill the gap, five one-quarter-scaled specimens (one bare frame and four braced frames) were tested subject to a pushdown loading regime. The RC frames were nonseismically detailed for reference. Four braced frames with different bracing configurations were tested to evaluate the efficiency of braces for upgrading the load-resisting capacity of RC frames. A rational design method was implemented for designing the braced frames, including the connections between the braces and RC frames. Experimental results proved that steel bracing could increase the first peak load and initial stiffness of the frames significantly. Before mobilization of catenary action in RC frames, the tensile braces were fractured, but the compressive braces experienced severe buckling. Consequently, the braced specimens performed similarly to the bare frame in the catenary action stage.

Long-Term Results of Compressive Brace Therapy for Pectus Carinatum

Pectus carinatum (PC) is one of the most common types of congenital chest wall deformity. Recently, noninvasive compressive brace therapy has been more frequently used than invasive surgical correction to treat PC. Hence, the purpose of this study was to determine the long-term outcome of compressive brace therapy. We retrospectively reviewed patients with PC who underwent compressive brace therapy between January 2014 and December 2016. All patients underwent a 2-week compression period, in which braces were worn for 20 hours per day, followed by a 6-month maintenance period, in which braces were worn for 12 hours per day. Patient satisfaction was investigated via telephone survey. A total of 320 patients were included in this study. The average age was 13 years, and 280 were males (87.5%). The median follow-up period was 42 months (13-68). Good compliance was observed in 286 patients (89.4%; compliance group). In this group, the initial Haller index significantly increased from 2.20 ± 0.31 to 2.59 ± 0.38 after the 6-month therapy period (p = 0.001). After the 6-month period, 255 patients (89.1%) and 31 patients (12.1%) in the compliance group were very satisfied and satisfied, respectively. Satisfaction at the last follow-up via telephone survey was very satisfied in 250 patients (87.4%) and satisfied in 36 (12.6%). In the compliance group, no patient needed compressive braces again after the therapy period. Given the findings presented in this study, compressive brace therapy appears to be a relatively simple and safe method with good long-term outcome in treating patients with PC.

Evaluation of the seismic performance of suspended zipper column concentrically braced steel frames

The performance of the most common type of concentric braced configuration, i.e. Chevron braces, is governed by buckling of first story braces in compression, resulting in a localization of the failure. To improve the performance of chevron concentric braced frames, zipper columns were introduced to transfer the unbalanced forces; over-strength braces were further introduced to avoid the complete collapse of the frame. Such concentric braced frames are called suspended zipper concentric braced frames.The objective of this study is to evaluate the seismic performance of suspended zipper concentric braced frames designed according to Eurocode 8 and to compare their performance with conventional concentric braced configurations. It is important to highlight that this study introduces a novel design methodology to size braces, zipper columns, beams and columns in suspended zipper frames. For this purpose, two concentric braced frame structures from each suspended zipper configuration and stud-to-ground configuration are designed and analysed for a ground motion with a probability of exceedance equal to 10% in 50 years, i.e. a return period of 475 years, with peak ground acceleration of 0.3 g.Based on the comparison of results, it can be concluded that the performance of suspended zipper frame is better than that of conventional concentrically braced frames in medium-rise buildings, but not in low-rise buildings. Furthermore, the novel design methodology is proven to be satisfactory in sizing the structural elements of suspended zipper concentric braced frames when considering the inelastic time history analyses results.

Can Diagnostic and Therapeutic Arthrocentesis Be Successfully Performed in the Flexed Knee?

The objective of this study was to determine whether the extended or flexed knee positioning was superior for arthrocentesis and whether the flexed knee positioning could be improved by mechanical compression. Fifty-five clinically effusive knees underwent arthrocentesis in a quality improvement intervention: 20 consecutive knees in the extended knee position using the superolateral approach, followed by 35 consecutive knees in the flexed knee position with and without an external compression brace placed on the suprapatellar bursa. Arthrocentesis success and fluid yield in milliliters were measured. Fluid yield for the extended knee was greater (191% greater) than the flexed knee (extended knee, 16.9 ± 15.7 mL; flexed knee, 5.8 ± 6.3 mL; P < 0.007). Successful diagnostic arthrocentesis (≥2 mL) was 95% (19/20) in the extended knee and 77% (27/35) in the flexed knee (P = 0.08). After mechanical compression was applied to the suprapatellar bursa and patellofemoral joint of the flexed knee, fluid yields were essentially identical (extended knee, 16.9 ± 15.7 mL; flexed knee, 16.7 ± 11.3 mL; P = 0.73), as were successful diagnostic arthrocentesis (≥2 mL) (extended knee 95% vs. flexed knee 100%, P = 0.12). The extended knee superolateral approach is superior to the flexed knee for conventional arthrocentesis; however, the extended knee positioning and flexed knee positioning have identical arthrocentesis success when mechanical compression is applied to the superior knee. This new flexed knee technique for arthrocentesis is a useful alternative for patients who are in wheelchairs, have flexion contractures, cannot be supine, or cannot otherwise extend their knee.

Seismic Behavior of Chevron Concentrically Braced Frames with Weak Beam

Concentrically braced frames provide ductility and imparted seismic energy dissipation through yielding of tension braces and buckling of compression braces. In braced frames with chevron configuration, difference of actions in tension and buckled brace results in considerable unbalanced force at brace-beam intersection, which is addressed in modern seismic design provisions. In this paper, effect of flexural capacity of beam to carry this unbalanced force and consequently seismic behavior of braced frame is investigated by finite element analysis. Two-story and four-story chevron braced frames were modeled in ABAQUS software and studied by means of nonlinear cyclic pushover and nonlinear response history analysis methods. Results showed that inadequate flexural strength of the beams reduce lateral stiffness and strength of braced frame significantly as lateral drift increases; therefore, concentration of lateral deformation in one story may cause formation of soft and weak story. Furthermore, seismic behavior of chevron braced frame and two-story X braced frames were compared.

Magnetic resonance imaging study of orthotic balloon brace used for the treatment of pectus carinatum

Aim: A compressive orthotic brace is considered the first line therapy for patients with pectus carinatum. We designed a brace made of a non-metallic binder equipped with a balloon which can be insufflated to apply variable compression pressure to chondrogladiolar pectus carinatum. The study aimed to study the effect of this brace on patients with pectus carinatum, dynamic magnetic resonance imaging (MRI) studies were obtained.

Analytical Investigation on Seismic Behavior of Inverted V-braced Frames

An inverted V-braced frame is one of the most widely used CBFs (Concentrically Braced Frames) owing to many advantages in constructional design. The seismic behaviors of inverted V-braced frames is that brace buckling occurs due to strong motion generation, and that in turn vertical unbalanced force is created between tension brace and compression brace, resulting in an additional load onto beams. Thus, members of beams should be designed to have enough strength to ensure plastic hinge is not created. In this study, a series of finite element analysis was conducted to evaluate the earthquake-resistant performances of the methods to design the clearance distance of gusset plates in inverted V-braced frames, and to evaluate vertical unbalanced force depending on the cross-section size of beams. It was found that the results of the equation of vertical unbalanced force in the current standards were more conservative than the load generated through the real analysis model. In addition, the model of designing elliptical clearance distance showed higher earthquake-resistant performances than that of designing linear clearance distance, which requires the reconsideration and improvement of the current practices of calculating vertical unbalanced force and setting clearance distance.

Finite Element Analysis on K-Type External Braced Steel Frame System

The concept of moment resisting frames with K-type external braces is proposed to increase the lateral stiffness, which has short external span and large lateral stiffness. In order to investigate the lateral stiffness, overstrength coefficient and the reduction factor of K-type external brace under horizontal load, ABAQUS was applied to study the different slenderness ratios (from50 to 150) of K-type external steel braced frames. The results showed that the lateral load and displacement curve can be divided into elastic stage, the buckling of the compressive brace-yield of the tensile brace stage and plastic stage. The overstrength of K-bracing is related to the potential bearing capacity of the frame when the compressive brace buckled, and the potential growth of the tensile brace. The overstrength coefficient increases with increasing of the brace slenderness ratio. The range of recommended values of slenderness ratios of K-type external steel braces and design values of unbalanced force of column sections are proposed.

Resistance of Axially Loaded T- and X-Joints of Elliptical Hollow Sections at Elevated Temperatures – A Finite Element Study

This study presents the results of a numerical study to develop a method to calculate the static strength of welded Elliptical Hollow Section (EHS) joints at elevated temperatures. Extensive numerical simulations using the non-linear finite element package, ABAQUS v6.14–1 on EHS T- and X-joints under brace axial compression or tension and pre-stress in chord member with different type of joint orientations at elevated temperatures over a wide range of diameter ratio have been conducted. The adjustments required to be made to the equations of joint resistance under ambient temperature conditions for estimating joint resistance at elevated temperature conditions are investigated in this study. The FE simulation results have been compared with the calculation results of a number of existing methods at ambient temperature. It has been found that the method proposed by Packer et al. gives the best agreement with the authors' simulation results at ambient temperature. At elevated temperatures, for T- and X- joints with braces in compression welded to the wide sides of chords, replacing the ambient temperature yield strength of steel by the elevated temperature value in the current design method overestimates the ultimate load carrying capacity of axially loaded EHS T- and X-joints due to inability of the ambient temperature calculation equations to take into consideration EHS flattening at high temperatures. For these cases, it is recommended to calculate the joint strength reduction factor at elevated temperatures according to the Young's modulus of steel.

EXPERIMENTAL STUDY ON LATERAL PERFORMANCE OF SHEAR WALL OF MODERN TIMBER ARCHITECTURE COMBINED WITH BRACE AND PLASTER USING WOOD LATH

In this study, in-plane shear tests of the seismic shear walls of modern timber architecture combined with brace and plaster using wood lath were conducted, and the failure mode, deformation performance and strength properties were discussed. The specimens are shown in Fig. 1 and Table1. Two types of the steel plate are used for the joints of the brace (see Fig. 2 and Fig. 3). Specimen1 is the wall using the only brace with the joint steel plate as shown in the existing architecture. Specimen2 is the wall using the only brace with the reinforced steel plate in joint. Specimen3 is the only plaster wall using wood lath. Specimen4 is the wall combined with brace (existing joint steel plate) and plaster using wood lath. Specimen5 is the wall combined with brace (reinforced steel plate) and plaster using wood lath. The results obtained from this study are summarized as follows. In the Specimen1, the joint steel plates were rotated in the early drift angle (see Photo3), and axial force were not acted on the tensile brace. At the drift angle of 1/30rad, the beam was broken (see Photo4) by bending moment because the compressive brace pushed up the beam. In the Specimen2, the strength properties were dramatically improved (see Fig. 8) because of the reinforced steel plate in joint. However, the bending fracture of the beam, which is the same as shown in Specimen1, occurred at the drift angle of 1/50rad. In the Specimen3, many cracks occurred at the corner of the plaster because of compressive stress (see Fig. 11). The strength of the plaster was the highest at the drift angle of 1/100rad, and the load decreased rapidly after that of 1/100rad. However, the load increased again after that of 1/50rad because wood lath was contacted with columns (see Fig. 10). In the Specimen4, the diagonal crack in the central area of plaster occurred in first, and then the crack at the corner of the plaster occurred (see Fig. 13). However, the number of the cracks at the drift angle of 1/100rad was lower than that of Specimen3. In the Specimen5, the cracks at the corner of the plaster occurred at the drift angle of 1/75rad (see Fig. 15). It is considered that the compressive stress will decrease by increasing the stiffness of the brace. The strength of the walls combined with brace and plaster shows good agreement with the sum of each strength of brace and plaster using wood lath.

Evaluating the efficacy of an active compression brace on orthostatic cardiovascular responses.

Orthostatic intolerance, one of the principle causes of syncope, can occur secondary to concomitant venous pooling and enhanced capillary filtration. We aimed to evaluate a prototype portable calf active compression brace (ACB) designed to improve orthostatic haemodynamic control. Fourteen healthy volunteers participated in a randomized, placebo controlled, cross-over, double-blind study. Testing consisted of head-upright tilting and walking on a treadmill conducted on two consecutive days with a pair of ACBs wrapped around both calves. The ACB was actuated on one test day, but not on the other (placebo). Wearability, comfort, and ambulatory use of the ACB were assessed using questionnaires. The average calf pressure exerted by the ACB was 46.3±2.2 mmHg and the actuation pressure was 20.7±1.7 mmHg. When considering the differences between ACB actuation and placebo during tilt after supine rest there were trends for a larger stroke volume (+5.20±2.34%, p = 0.05) and lower heart rate (-5.12±2.41%, p = 0.06) with ACB actuation, with no effect on systolic arterial pressure (+4.86±3.41%, p = 0.18). The decrease in stroke volume after ten minutes of tilting was positively correlated with the height:calf circumference (r = 0.464; p = 0.029; n = 22; both conditions combined). The increase in heart rate after ten minutes of tilting was negatively correlated with the height:calf circumference (r = -0.485; p = 0.022; n = 22; both conditions combined) and was positively correlated with the average calf circumference (r = 0.539; p = 0.009; n = 22; both conditions combined). Participants reported good ACB wearability and comfort during ambulatory use. These data verify that the ACB increased stroke volume during tilting in healthy controls. Active calf compression garments may be a viable option for the management of orthostatic intolerance.

Elastic buckling of steel arches with discrete lateral braces

Lateral brace is an effective way to increase the out-of-plane stability of steel arches, and the certain bracing stiffness achieving full restraining effect is concerned. Unlike braced columns and beams, the buckling of steel arches with discrete lateral braces and the effect of bracing stiffness are not well explored. This paper deals with the bracing stiffness effect of equally-spaced lateral translational braces and rotational braces in steel circular arches pertaining to elastic out-of-plane flexural-torsional buckling. Firstly, for arches with discrete lateral translational braces in uniform compression, an analytical solution for the threshold bracing stiffness is derived by the Rayleigh–Ritz method, ensuring full restraint of the displacement at the bracing points. Then for arches with discrete rotational braces in uniform compression, the flexural-torsional buckling modes are explored using the finite element analysis (FEA), then improved predictions to the buckling load related to the bracing stiffness are obtained theoretically by assuming proper buckling shapes. Compared with the FEA results, it is found that the analytical solutions of threshold stiffness proposed for arches in uniform compression are reasonably accurate and can be used in other loading cases for arches under combined compression and bending moment conservatively.

A Single-Center Experience with Dynamic Compression Bracing for Children with Pectus Carinatum.

Bracing for pectus carinatum (PC) has emerged as an alternative to surgical correction. However, predictive factors for bracing remain poorly understood, as much of the data have been reported from small series. We reviewed a prospective dataset in patients with PC who underwent dynamic compression bracing (DCB) from July 2011 to July 2016. Bracing was initiated in patients > 10 years of age with a significant PC and desire for bracing. Data were analyzed for those observed two or more times after the brace was fitted to the patient. A total of 503 patients were evaluated for PC and 340 (68%) underwent DCB. Eighty-five percent were males with an average age of 14 ± 2 years. There was a positive correlation of age with pressure of initial correction (PIC, r = 0.2). One patient underwent operative correction as the initial therapy. Two hundred seventeen patients had two or more visits after the patient was fitted for the brace. The mean PIC in this cohort was 4 psi (range: 1.5-7.8), and the median duration of bracing in this group was 16 months (IQR: 7-23 months). One hundred three patients (47%) achieved complete correction after an average bracing time of 7.5 months and were then placed in the retainer mode. Thirty patients successfully completed bracing therapy and required an average of 23 months of therapy (2 months-4 years). No patient recurred after bracing was completed, but one failed bracing and required operative correction. Complications included mechanical problems (8%), skin complications (10%), complaints of tightness (3%), and pain (2%). DCB has both early and lasting effects in the correction of PC with minimal complications. Predictive factors for successful resolution of the PC include increased duration of DCB and lower initial PIC.

I.11.03: Influence of splitting beam and column stiffness on CBFS ductile behaviour

ABSTRACTConcentrically braced frames with X‐bracing configuration (X‐CBFs) are one of the most popular systems for seismic resistant design. Their ductile behaviour is provided primarily by yielding of braces in tension and to a small extent by plastic rotation in buckled braces. An improved CBF configuration by introducing bracings with modified sections was developed in research program. In order to facilitate joint detailing, it is efficient that braces intersect into a horizontal member named ”splitting beam”. Experimental study has shown that braces, being above and below the splitting beam, often do not buckle simultaneously. This leads to concentration of inelastic deformations within one of the brace and causes unbalanced horizontal and vertical force. Finally, it might result in reduced storey ductility and premature brace fracture.It was assessed through extensive parametric non‐linear analysis that splitting beams in cooperation with columns have crucial impact on the brace buckling sequence and on the type of the global plastic mechanism. An analytical model and design procedure for determining the stiffness and strength demand of splitting beams and braced frame columns are proposed. The procedure ensures achievement of buckling of both halves of compression braces and formation of anticipated plastic mechanism. Some case studies based on static nonlinear analysis are presented.

A Shape Memory Alloy-Based Compression Therapy Prototype Tested With Individuals in Seated Position

Orthostatic intolerance in patients can occur secondary to concomitant venous pooling and enhanced capillary filtration when standing upright, and is one of the principle causes of syncope or fainting. Compression therapy is commonly recommended for the management of syncope based on the assumption that it increases venous return. Technologies currently used include compression stockings, whose efficacy has, however, been challenged, and intermittent pneumatic pressure devices, which highly restrict the patients' mobility. This paper therefore investigates a novel active compression brace (ACB), which could potentially provide intermittent pressure while not restricting movements. The ACB, actuated by shape memory alloy (SMA) wires, in this work was tested with twelve healthy individuals in a seated position. The experimental observation showed that the ACB can apply a constant initial pressure to the leg similar to commercial compression stockings and also produce intermittent pressure exceeding 30 mmHg. A comparison between analytical and experimental results showed a maximum of 2.08 mmHg absolute averaged difference among all the participants. A correlation analysis showed that the normalized root-mean-square deviation (NRMSD) between the experimental and analytical results had a significant negative correlation with the estimated total calf circumference minus the calf fat cross-sectional area (CSA). A calibration formula, accounting for fat and circumference of the leg, was introduced to account for these two parameters. The comfort of the ACB was also compared to two other available compression devices using questionnaires. No participants reported discomfort in terms of pressure, skin irritation, or heat generated by the ACB.