scholarly journals Development of a Class-C Power Amplifier with Diode Expander Architecture for Point-of-Care Ultrasound Systems

Micromachines ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 697 ◽  
Author(s):  
Hojong Choi
Keyword(s):  
Power Amplifier ◽  
Power Amplifiers ◽  
Point Of Care ◽  
Ultrasonic Transducer ◽  
Input Pulse ◽  
Point Of Care Ultrasound ◽  
Potential Candidate ◽  
Excessive Heat ◽  
System Sensitivity ◽  
Class C

Point-of-care ultrasound systems are widely used in ambulances and emergency rooms. However, the excessive heat generated from ultrasound transmitters has an impact on the implementation of piezoelectric transducer elements and on battery consumption, thereby affecting the system’s sensitivity and resolution. Non-linear power amplifiers, such as class-C amplifiers, could substitute linear power amplifiers, such as class-A amplifiers, which are currently used in point-of-care ultrasound systems. However, class-C power amplifiers generate less output power, resulting in a reduction of system sensitivity. To overcome this issue, we propose a new diode expander architecture dedicated to power amplifiers to reduce the effects of sinusoidal pulses toward the power supply. Thus, the proposed architecture could increase the input pulse amplitudes applied to the main transistors in the power amplifiers, hence increasing the output voltage of such amplifiers. To verify the proposed concept, pulse-echo responses from an ultrasonic transducer were tested with the developed class-C power amplifier using a resistor divider and the designed diode expander architecture. The peak-to-peak amplitude of the echo signals of the ultrasonic transducers when using a class-C power amplifier with a diode expander architecture (2.98 Vp–p) was higher than that for the class-C power amplifier with a resistor divider architecture (2.51 Vp–p). Therefore, the proposed class-C power amplifier with diode expander architecture is a potential candidate for improving the sensitivity performance of piezoelectric transducers for point-of-care ultrasound systems.

scholarly journals Wide Bandwidth Class-S Power Amplifiers for Ultrasonic Devices

Sensors ◽  
2020 ◽  
Vol 20 (1) ◽  
pp. 290 ◽  
Author(s):  
Kiheum You ◽  
Hojong Choi
Keyword(s):  
Power Amplifier ◽  
Power Amplifiers ◽  
Ultrasonic Transducer ◽  
Wide Frequency Range ◽  
Frequency Range ◽  
Wide Bandwidth ◽  
Class A ◽  
Ultrasonic Devices ◽  
Constant Output ◽  
Pulse Echo

Wide bandwidth ultrasonic devices are a necessity in high-resolution ultrasonic systems. Therefore, constant output voltages need to be produced across the wide bandwidths of a power amplifier. We present the first design of a wide bandwidth class-S power amplifier for ultrasonic devices. The −6 dB bandwidth of the developed class-S power amplifier was measured at 125.07% at 20 MHz, thus, offering a wide bandwidth for ultrasonic devices. Pulse-echo measurement is a performance measurement method used to evaluate the performance of ultrasonic transducers, components, or systems. The pulse-echo signals were obtained using an ultrasonic transducer with designed power amplifiers. In the pulse-echo measurements, time and frequency analyses were conducted to evaluate the bandwidth flatness of the power amplifiers. The frequency range of the ultrasonic transducer was measured and compared when using the developed class-S and commercial class-A power amplifiers with the same output voltages. The class-S power amplifiers had a relatively flat bandwidth (109.7 mV at 17 MHz, 112.0 mV at 20 MHz, and 109.5 mV at 23 MHz). When the commercial class-A power amplifier was evaluated under the same conditions, an uneven bandwidth was recorded (110.6 mV at 17 MHz, 111.5 mV at 20 MHz, and 85.0 mV at 23 MHz). Thus, we demonstrated that the designed class-S power amplifiers could prove useful for ultrasonic devices with a wide frequency range.

Case Report: When all claims that it is necrotizing fasciitis but Point of care ultrasound (POCUS) proves the opposite!

POCUS Journal ◽  
2018 ◽  
Vol 3 (1) ◽  
pp. 13-14
Author(s):  
Hadiel Kaiyasah, MD, MRCS (Glasgow), ABHS-GS ◽  
Maryam Al Ali, MBBS
Keyword(s):  
Emergency Department ◽  
Critical Care ◽  
Case Report ◽  
Soft Tissue ◽  
Necrotizing Fasciitis ◽  
Soft Tissue Infection ◽  
Critical Care Unit ◽  
Point Of Care ◽  
Point Of Care Ultrasound ◽  
Soft Tissue Infections

Soft tissue ultrasound (ST-USS) has been shown to be of utmost importance in assessing patients with soft tissue infections in the emergency department or critical care unit. It aids in guiding the management of soft tissue infection based on the sonographic findings.

Pilot Project: Does formal bedside training of medical students with a FAST exam increase their knowledge and comfort level with ultrasound use in a community family medicine practice setting?

POCUS Journal ◽  
2017 ◽  
Vol 2 (2) ◽  
pp. 15-17
Author(s):  
Rimi Sambi, MD ◽  
Heather Sawula, MD ◽  
Brent Wolfrom, MD ◽  
Joseph Newbigging, MD
Keyword(s):  
Medical Students ◽  
Family Medicine ◽  
Point Of Care ◽  
Training Session ◽  
Undergraduate Curriculum ◽  
Knowledge Retention ◽  
Comfort Level ◽  
Point Of Care Ultrasound ◽  
Medical Undergraduate ◽  
Fast Exam

As point of care ultrasound (PoCUS) becomes increasingly popular and a standard of care in many clinical settings, the interest for integration in medical undergraduate curriculum is also growing [1]. This project aims to assess whether formal bedside Focused Abdominal Scan for Trauma (FAST) exam training of medical students increases their knowledge and comfort with the use of bedside ultrasound in a family medicine setting at Queen’s University. Third year medical students (n=18) were recruited to participate in a training session involving a 1-hour online video and 2-hour hands-on session. Knowledge based surveys were completed before and after the training. A survey was completed 4 months after the teaching session evaluating knowledge retention, comfort, and application of skills. Student knowledge of PoCUS and FAST increased and was maintained (pre-training 56%±20%, post-training 82%±10%, p<0.001). Self-evaluation of comfort performing a FAST examination (5-point Likert scale) similarly increased post-training session (pre-training 1.4±0.8, post-training 3.8±0.9, p<0.005), but decreased 4 months later (3±1.2, p<0.005). Students in this study were unanimously interested in ultrasound training and the methods used effectively increased theoretical knowledge and comfort with use. Students did not retain their comfort levels with FAST exam 4 months after the training session, nor did they have the opportunity to utilize the skills learned. Further evidence is required to identify the applicability of these results to undergraduate curriculum development.

Telemedicine-guided point-of-care ultrasound can be feasible and effective in a life-threatening situation: The case of a field hospital during the COVID-19 pandemic (Preprint)

2020 ◽  
Author(s):  
Tarso Accorsi ◽  
Karine De Amicis Lima ◽  
Alexandra Brigido ◽  
Deborah Belfort ◽  
Fabio Habrum ◽  
...  
Keyword(s):  
Point Of Care ◽  
Image Interpretation ◽  
Acquisition Time ◽  
Point Of Care Ultrasound ◽  
Field Hospital ◽  
Portable Ultrasound ◽  
Local Staff ◽  
Assessment Protocol ◽  
Life Threatening ◽  
Threatening Situation

BACKGROUND Lightweight portable ultrasound is widely available, especially in inaccessible geographical areas. It demonstrates effectiveness and diagnosis improvement even in field conditions but no precise information about protocols, acquisition time, image interpretation, and the relevance in changing medical conduct exists. The COVID-19 pandemic implied many severe cases and the rapid construction of field hospitals with massive general practitioner (GP) recruitment. OBJECTIVE This prospective and descriptive study aimed to evaluate the feasibility of telemedicine guidance using a standardized multi-organ sonographic assessment protocol in untrained GPs during a COVID-19 emergency in a field hospital. METHODS Eleven COVID-19 in-patients presenting life-threatening complications, attended by local staff who spontaneously requested on-time teleconsultation, were enrolled. All untrained doctors successfully positioned the transducer and obtained key images guided by a remote doctor via telemedicine, with remote interpretation of the findings. RESULTS Only four (36%) general practitioners obtained the appropriate key heart image on the left parasternal long axis window, and three (27%) had an image interpreted remotely on-time. The evaluation time ranged from seven to 42 minutes, with a mean of 22.7 + 12. CONCLUSIONS Telemedicine is effective in guiding GPs to perform portable ultrasound in life-threatening situations, showing effectiveness in conducting decisions.

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