Inflatable Air Bladders Research Articles

A Prosthetic Socket with Active Volume Compensation for Amputated Lower Limb.

Typically, the actual volume of the residual limb changes over time. This causes the prosthesis to not fit, and then pain and skin disease. In this study, a prosthetic socket was developed to compensate for the volume change of the residual limb. Using an inflatable air bladder, the proposed socket monitors the pressure in the socket and keeps the pressure distribution uniform and constant while walking. The socket has three air bladders on anterior and posterior tibia areas, a latching type 3-way pneumatic valve and a portable control device. In the paper, the mechanical properties of the air bladder were investigated, and the electromagnetic analysis was performed to design the pneumatic valve. The controller is based on a hysteresis control algorithm with a closed loop, which keeps the pressure in the socket close to the initial set point over a long period of time. In experiments, the proposed prosthesis was tested through the gait simulator that can imitate a human’s gait cycle. The active volume compensation of the socket was successfully verified during repetitive gait cycle using the weight loads of 50, 70, and 90 kg and the residual limb model with a variety of volumes. It was confirmed that the pressure of the residual limb recovered to the initial state through the active control. The pressure inside the socket had a steady state error of less than 0.75% even if the volume of the residual limb was changed from −7% to +7%.

Effectiveness of abdominal compression in reducing internal target motion during conformal radiotherapy for carcinoma stomach - A pilot study.

: To assess the effectiveness of abdominal compression in reducing internal target motion during conformal radiotherapy for stomach cancer. A pilot study was conducted on five patients who received adjuvant radiotherapy for stomach cancer. All the patients had surgical clips and were offered radiotherapy and concurrent chemotherapy as per the institutional protocol. An abdominal compression device was developed consisting of a triangular Styrofoam's plate and an inflatable air bladder that was positioned over the patients' abdomen. The pneumatic pressure was set according to the patients' comfort. On the simulation day, patients had two computed tomography (CT)-scanning sessions, with and without abdominal compression. Target volumes and organs at risk (OAR) were delineated on the CT images without compression. On the treatment day, fluoroscopy was acquired with onboard imager (OBI) and movements of surgical clips with and without compression analyzed with the help of a tracker software. Observed values with and without abdominal compression were compared. Abdominal compression usage has reduced the mean breathing excursion (MBE) in medio lateral(ML) direction from 5.92mm to 4.15 mm and in cranio caudal direction (CC) from 11.3mm to 7.2mm. The range of reduction by 29.85% in the ML and 36.86% in CC direction. The average residual breathing excursion was 1.766 mm (SD = 1.33 mm) in the ML and 4.02 mm (SD = 2.18 mm) in the CC direction, respectively. Abdominal compression was useful in reducing internal target motion during stomach cancer conformal radiotherapy. The device we developed is patient friendly and cost-effective.

SU‐E‐J‐12: An Image‐Guided Soft Robotic Patient Positioning System for Maskless Head‐And‐Neck Cancer Radiotherapy: A Proof‐Of‐Concept Study

Purpose:We propose a surface‐image‐guided soft robotic patient positioning system for maskless head‐and‐neck radiotherapy. The ultimate goal of this project is to utilize a soft robot to realize non‐rigid patient positioning and real‐time motion compensation. In this proof‐of‐concept study, we design a position‐based visual servoing control system for an air‐bladder‐based soft robot and investigate its performance in controlling the flexion/extension cranial motion on a mannequin head phantom.Methods:The current system consists of Microsoft Kinect depth camera, an inflatable air bladder (IAB), pressured air source, pneumatic valve actuators, custom‐built current regulators, and a National Instruments myRIO microcontroller. The performance of the designed system was evaluated on a mannequin head, with a ball joint fixed below its neck to simulate torso‐induced head motion along flexion/extension direction. The IAB is placed beneath the mannequin head. The Kinect camera captures images of the mannequin head, extracts the face, and measures the position of the head relative to the camera. This distance is sent to the myRIO, which runs control algorithms and sends actuation commands to the valves, inflating and deflating the IAB to induce head motion.Results:For a step input, i.e. regulation of the head to a constant displacement, the maximum error was a 6% overshoot, which the system then reduces to 0% steady‐state error. In this initial investigation, the settling time to reach the regulated position was approximately 8 seconds, with 2 seconds of delay between the command start of motion due to capacitance of the pneumatics, for a total of 10 seconds to regulate the error.Conclusion:The surface image‐guided soft robotic patient positioning system can achieve accurate mannequin head flexion/extension motion. Given this promising initial Result, the extension of the current one‐dimensional soft robot control to multiple IABs for non‐rigid positioning control will be pursued.

How does pressure configuration affect Cobb angle during AIS brace casting?

Methods Nine AIS patients undergoing casting for new braces participated in this pilot study (2 males, 7 females, aged 11-16, Cobb angles 16-44 degrees). An ultrasound scan was used to measure the patient’s (baseline) Cobb angle. The orthotist then used a custom standing Providence system to apply corrective pressures simulating a brace. A second ultrasound scan measured the new (corrected) Cobb angle. The orthotist could then try to achieve additional correction by adjusting the pressure magnitude/location. The process of adjusting pressures and ultrasound scanning repeated two or three times; the orthotist then chose the most satisfactory pressure configuration and performed the actual casting. The procedure produced 26 individual scans (including baseline scans) from the 9 patients. The magnitude of applied pressures was measured using inflatable air bladders fixed to the Providence pads. The air pressure was measured during the ultrasound scan. The distance between pads was measured and multiplied by the total pressure to create a torque-like measurement. Robust linear regression was used to relate pressure with Cobb angle correction, and torque with correction. Outlier points were removed if they fell more than 1.5 standard deviations from the regression line. Correlations between pressure/torque and correction were then measured. Results Two outlier points were removed both belonging to a single patient. Pressures ranged from 16-113 mmHg. The major curves’ correction ranged from 0-39%. Significant correlations existed between average pressure and Cobb angle correction (r = 0.86, p < 0.01), and average torque and Cobb angle correction (r = 0.82, p < 0.01).

The Effectiveness of a Pneumatic Compression Belt in Reducing Respiratory Motion of Abdominal Tumors in Patients Undergoing Stereotactic Body Radiotherapy

Abdominal compression using a pneumatic abdominal compression belt developed in-house has been used to reduce respiratory motion of patients undergoing hypo-fractionated or single fraction stereotactic radio-ablative therapy for abdominal cancers. The clinical objective of belt usage was to reduce the cranial-caudal (CC) respiratory motion of the tumor to 5 mm or less during both CT simulation and treatment. A retrospective analysis was done to determine the effectiveness of the device and associated clinical procedures to reduce the CC respiratory motion of the tumor. 42 patients treated for tumors in the liver (30), adrenal glands (6), pancreas (3) and lymph nodes (3) using high dose hypofractionated radiotherapy between 2004 and the present were eligible for analysis. All patients had 2-3 radiopaque fiducial markers implanted near the tumor prior to simulation, or had clips from prior surgery. Integral to the belt is an inflatable air bladder that is positioned over the abdomen. The pneumatic pressure was set to a level in consultation with the patient. The CC motion was measured fluoroscopically with and without pneumatic pressure. Pneumatic pressure was used at all treatments to reduce to CC motion to that achieved at simulation. The mean CC motion with the belt in place, but no additional air pressure was 11.4 mm with a range of 5-20 mm. With the pressure applied, the mean CC motion was reduced to 4.4 mm with a range of 1-8 mm (P-value < 0.001). The clinical objective of reducing the CC motion of the tumor to a maximum excursion of 5 mm or less was achieved in 93% of cases. The use of a pneumatic compression belt and associated clinical procedures was found to result in a significant and frequently substantial reduction in the CC motion of the tumor.

A Preliminary Assessment of a Novel Pneumatic Unloading Knee Brace on the Gait Mechanics of Patients With Knee Osteoarthritis

To determine whether a knee brace incorporating inflatable air bladders can alter the net peak external knee adduction moment in persons with medial compartment knee osteoarthritis. Prospective cohort study. Motion analysis laboratory. Subjects (n= 18) diagnosed with knee osteoarthritis as defined by the Diagnostic and Therapeutic Criteria Committee of the American Rheumatism Association. Instrumented gait analysis was performed while subjects walked with and without the knee brace. When subjects wore the knee brace, the air bladders were either uninflated or inflated to 7 psi. The net external knee adduction moment was obtained by subtracting the abduction moment produced by the knee brace (estimated using a finite element analysis model) from the external knee adduction moment (estimated using a camera-based motion analysis system). The net external knee adduction moment was compared across all testing conditions. A 7.6% decrease in net peak external knee adduction moment was observed when subjects wore the knee brace uninflated compared with when they did not wear the brace. Inflation of the bladders to 7 psi led to a 26.0% decrease in net peak external knee adduction moment. The results of the study suggest that the effects of an unloading knee brace may be enhanced by incorporating inflatable air bladders into the design of the brace, thus leading to an improved correction of the excessive peak external knee adduction moment observed in patients with medial compartment knee osteoarthritis.

Restoration of Meibomian Gland Functionality With Novel Thermodynamic Treatment Device-A Case Report

A new and previously unpublished thermodynamic treatment device, which for the first time applies heat directly to both inner eyelid surfaces with a precision-controlled resistive heater while pulsating pressure is simultaneously applied to the outer eyelids using an inflatable air bladder, was used to restore meibomian gland functionality for a subject with severe evaporative dry eye. The subject, a 39-year-old white woman of light complexion with severe symptoms and corroborating objective signs of dry eye, had been unsuccessfully treated for 3 years by 7 practitioners. Using a new standardized meibomian gland expression device, a diagnosis of nonobvious meibomian gland dysfunction, where none of the approximately 24 meibomian glands of the right lower eyelid and 1 meibomian gland of the left lower eyelid were functional, was made. The patient underwent a single 12-minute treatment per eye with the treatment device. The treatment restored the functionality of 8 glands in each eye, doubled the fluorescein break-up time (FBUT) from 5 to 10 seconds, and decreased the symptom scores by approximately 80% for the entire follow-up period of 3 months.

Splanchnic Compression Improves the Efficacy of Compression Stockings to Prevent Orthostatic Intolerance

Purpose: Post-spaceflight orthostatic intolerance (OI) is observed in 20-30% of astronauts. Previous data from our laboratory suggests that this is largely a result of decreased venous return. Currently, NASA astronauts wear an anti-gravity suit (AGS) which consists of inflatable air bladders over the calves, thighs and abdomen, typically pressurized from 26 to 78 mmHg. We recently determined that, thigh-high graded compression stockings (JOBST , 55 mmHg at ankle, 6 mmHg at top of thigh) were effective, though to a lesser degree than the AGS. The purpose of this study was to evaluate the addition of splanchnic compression to prevent orthostatic intolerance. Methods: Ten healthy volunteers (6M, 4F) participated in three 80 head-up tilts on separate days while (1) normovolemic (2) hypovolemic w/ breast-high compression stockings (BS)(JOBST(R), 55 mmHg at the ankle, 6 mmHg at top of thigh, 12 mmHg over abdomen) (3) hypovolemic w/o stockings. Hypovolemia was induced by IV infusion of furosemide (0.5 mg/kg) and 48 hrs of a low salt diet to simulate plasma volume loss following space flight. Hypovolemic testing occurred 24 and 48 hrs after furosemide. One-way repeated measures ANOVA, with Bonferroni corrections, was used to test for differences in blood pressure and heart rate responses to head-up tilt, stand times were compared using a Kaplan-Meyer survival analysis. Results: BS were effective in preventing OI and presyncope in hypovolemic test subjects ( p = 0.015). BS prevented the decrease in systolic blood pressure seen during tilt in normovolemia (p < 0.001) and hypovolemia w/o countermeasure (p = 0.005). BS also prevented the decrease in diastolic blood pressure seen during tilt in normovolemia (p = 0.006) and hypovolemia w/o countermeasure (p = 0.041). Hypovolemia w/o countermeasure showed a higher tilt-induced heart rate increase (p = 0.022) than seen in normovolemia; heart rate while wearing BS was not different than normovolemia (p = 0.353). Conclusion: BS may be an effective countermeasure to post-space flight OI. The addition of splanchnic compression is more effective than the previous thigh-high garments. These stockings are readily available, inexpensive, and can be worn for days following landing as astronauts re-adapt to Earth gravity.

Graded Compression Stockings Prevent Post-spaceflight Orthostatic Hypotension

Post-spaceflight orthostatic intolerance is characterized by hypotension and presyncope in 20-30% of returning astronauts. Previous data from our laboratory suggests that this is largely a result of decreased venous return. Currently, NASA astronauts wear an anti-gravity suit (AGS) which consists of inflatable air bladders over the calves, thighs and abdomen, which are typically pressurized from 0.5 to 1.5 PSI (~27 to 78 mmHg). ISS crew members sometimes wear Russian Kentavr suits which consist of laced compression shorts and gaiters, providing ~30 mmHg nominally. While these garments are effective during reentry, there are a number of drawbacks that make them impractical for postflight use. We studied the ability of commercially available, custom fit, graded compression stockings (Jobst, 55 mmHg at ankle to 6 mmHg at top of thigh, 25 mmHg mean compression) to prevent postflight orthostatic intolerance, hypothesizing that these garments would prevent orthostatic intolerance following short duration space flight. Crew members from a single Space Shuttle flight were tilted to 80 degrees for 10 min while wearing the stockings (n=5 males) upon arrival at the clinic (~2 hrs after landing). Hemodynamic data were compared to data from all crewmembers tilted (without countermeasures) since return to flight (n=9). Two-way, repeated measures ANOVA, using the entire tilt time curve (0-10 min) show that systolic blood pressure (SBP, group effect p=0.008), stroke volume (SV, group effect p=0.003), and cardiac output (CO, group effect p=0.004) were higher in crewmembers who wore the Jobst stockings. A one-way ANOVA comparing the last minute standing also showed that SV (p=0.001) and CO (p less than 0.001) were higher and SBP tended to be higher (p=0.06) in Jobst subjects compared to controls. Control subjects had a higher rate of presyncope than Jobst subjects (3/9 vs 0/5) during the tilt on landing day. Orthostatic hypotension continues to present following spaceflight, despite fluid loading and other countermeasures. This preliminary study shows that commercially available compression stockings may ameliorate this problem. These stockings are readily available, inexpensive, and can be worn for days following landing. We have observed similar protection against orthostatic intolerance in ground-based studies of hypovolemic test subjects. Further refinements to the design and compression of the stockings are in progress.

Multilayer conformal applicator for microwave heating and brachytherapy treatment of superficial tissue disease

Purpose: The purpose of this study was to construct and perform preliminary functionality evaluations of a multilayer conformal applicator with provisions for thermal monitoring, tight conformity and simultaneous microwave heating and brachytherapy treatment of large-area contoured surfaces.Materials and methods: The multilayer conformal applicator consists of thermal monitoring catheters for fibre-optic monitoring of skin temperatures, a waterbolus, a PCB microwave antenna array, a dielectric spacer for brachytherapy considerations, brachytherapy catheters for delivering HDR radiation and an inflatable air bladder for improving conformity to contoured surfaces. The applicator also includes an elastic attachment structure to hold the applicator securely in place on the patient. The conformity of the applicator to irregular surfaces was evaluated through CT imaging of the applicator fitted onto a life-sized human torso phantom. The fluid flow dynamics of the waterbolus, which impact the effectiveness of temperature control, were evaluated with thermometry during a 19°C step change temperature of the circulating water.Results: CT imaging showed improved conformity to the torso phantom surface following the application of gentle inward pressure from inflating the outer air bladder. Only a small number of 1–5 mm sized air gaps separated the conformal applicator and tissue surface. Thermometry testing of the bolus fluid flow dynamics demonstrated temperature uniformity within ±0.82°C across a 19 × 34 × 0.6 cm area bolus and ±0.85°C across a large 42 × 32 × 0.6 cm area bolus.Conclusion: CT scans of the applicator confirmed that the applicator conforms well to complex body contours and should maintain good conformity and positional stability even when worn on a mobile patient. Thermometry testing of two different waterbolus geometries demonstrated that uniform circulation and temperature control can be maintained throughout large, complex bolus shapes.

EFFECTS OF A NEUROMUSCULAR TRAINING PROGRAM ON BALANCE IN OLDER ADULTS

Studies in the area of balance have shown that the hip girdle musculature is involved in one of the main strategies employed in regaining balance. It has also been shown that 12 week strength training programs undertaken at any age can show modest improvements in strength and profound effects in functional independence. Purpose: To examine the relationship between neuromuscular recruitment in the muscles associated with the hip girdle and functional balance in a 12 week training program with healthy older adults. Methods: Forty-four women aged 70 and older volunteered into the control (n1 = 22, Mean Age = 75.91 ± 3.66) or training group (n2 = 22, Mean Age = 76.05 ± 4.78). Subjects were tested on 2 functional lower body tests; a Timed Two-Legged Squat (TTLS) and Timed Chair Stand (TCS). Functional balance was assessed using the Kinesthetic Ability Trainer (KAT). The KAT uses an inflatable air bladder to alter the stability of the platform. Platform stability was timed under 3 conditions (psi levels: 1.0, 2.5, 4.0) with eyes open and closed. Subjects in the training group were allotted to training workouts consisting of 1 hour stretching and strengthening programs 3x/wk for 12 weeks. Subjects in the comparison group were asked to maintain their daily routines and not participate in additional activities. A subjective questionnaire on general well-being was administered to both groups after the completion of the study. Results: Currently with 9 of 22 completed 12 weeks of training (n1 = 9, n2 = 9), a 2×2 ANOVA with repeated measures on one factor demonstrated a statistical significant effect in the TTLS (p = 0.01), and TCS (p < 0.01). As well, as expected, the TTLS was negatively correlated with the TCS. The results of the questionnaire suggest that undertaking a strength-training program can improve one's quality of life. However, no significant difference was noted under any of the balance conditions. Conclusion: These results suggest that resistance training improves strength, functional independence and quality of life. Further research, with larger sample sizes, is warranted to assess the effects on balance.

Indirect Measurement of Systolic Blood Pressure in the Rabbit

Long-term studies of rabbit blood pressure require a reliable method for repeated blood pressure measurements. Ideally, this method would be simple, noninvasive, and accurate over the range of anticipated blood pressures. To facilitate our own studies of rabbit carotid artery graft patency, we have developed a technique for the indirect measurement of systolic blood pressure in the rabbit that utilizes a photoplethysmograph sensor placed distal to an inflatable air bladder positioned over the central ear artery. We have compared measurements obtained with this method to direct measurements of aortic pressure and found a linear correlation.

Noise attenuating apparatus for modulating air flow

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