In vitro comparative study of wall portbased high-frequency chest wall oscillation device and internal air-pulse generator device.

Owing to environmental and disease issues, the use of high-frequency chest wall oscillation (HFCWO) devices in hospitals is consistently increasing. This study proposes a cost-effective actuator-less HFCWO device that utilizes an external wall port utility in hospitals to generate the positive and negative pneumatic pressures required for HFCWO treatment instead of an embedded mechanical actuator. The manufactured prototype with the no-amplification (NO-AMP) setting contained an electric pressure regulator to enable intensity level adjustment and two solenoid valves to enable vibration frequency adjustment, whereas the prototype with the pre-amplification (PRE-AMP) setting contained an additional air reservoir and an air-pressure booster. The prototype device was tuned to output average local maximum values in the pressure waveform similar to a commercial VEST-205 device at an 8-12 Hz frequency and 2-4 pressure intensity levels. In vitro comparative experiments demonstrated that the prototype device showed similar local maximum pressures to those of the VEST-205 (mean absolute pressure difference, <3 mmH2O); in contrast, the proposed device showed significantly higher local minimum pressures than those of the VEST-205 (mean absolute pressure difference, >8 mmH2O). Additionally, the driving sound of the proposed device was 17.0-17.8 dB higher than that of VEST-205. We conclude that the proposed device has the potential to substitute for conventional HFCWO devices under the limited but most frequently used operating conditions, although more detailed modifications are necessary in future studies to improve its performance and clinical usability.

Capacitive coupling leading to electrical skin burn injury during laparoscopic surgery.

Purpose: Trocar-site burns occurring during laparoscopic surgery have been reported in various cases, and several efforts to reduce them are underway. This study aimed to analyze the effect of capacitive coupling on trocar site by observing electrical and histological changes for electrical skin burn injury. Methods: To measure the electrical changes relating to capacitive coupling, the temperature, current, voltage, and impedance around the trocar were measured when an open circuit and a closed circuit were formed using insulation intact instruments and repeated after insulation failure. After the experiment, the tissue around the trocar was collected, and microscopic examination was performed. Results: When open circuits were formed with the intact insulation, the impedance was significantly reduced compared to the cases of closed circuits (142.0 Ω vs. 109.3 Ω, p = 0.040). When the power was 30 W and there was insulation failure, no significant difference was measured between the open circuit and the closed circuit (147.7 Ω vs. 130.7 Ω, p = 0.103). Collagen hyalinization, nuclear fragmentation, and coagulation necrosis suggesting burns were observed in the skin biopsy at the trocar insertion site. Conclusion: This study demonstrated that even with a plastic trocar and electrosurgical instruments that have intact insulation, if an open circuit is formed, capacitive coupling increases, and trocar-site burn can occur. When using electrocautery, careful manipulation must be taken to avoid creating an open circuit to prevent capacitive coupling related to electrical skin burn.

A new injection rate estimation technique for on-site screening test of medication infusion pump by nurses.

Medication infusion pumps are the most popular device in almost all areas of a hospital; therefore, it is important to frequently inspect the accuracy of the infusion pump operation to prevent underdose/overdose accidents. However, the conventional infusion pump inspection devices are not suitable for quick and convenient on-site inspection by nurses. In this study, a new IR estimation technique for peristaltic infusion pumps that facilitates on-site pre-screening test with shorter inspection time was proposed. A thin membrane potentiometer was attached to a catheter and the actual IR was estimated based on a time interval between two successive line pushes of an identical cam follower using power function estimation. To evaluate the performance of the proposed IR estimation technique, in vitro experiments were performed using 11 infusion pumps (three for Infusion Pump SET 1 (IPSET-1) and eight for Infusion Pump SET 2 (IPSET-2)) with the same model. In experiments, error rate between the actual and the measured values (using conventional inspection device) were 0.04-1.17% range for IPSET-1 and 2.09-4.32% for IPSET-2, and those between the actual and the estimated values (using proposed method) were 0.02-0.62% range for IPSET-1 and 1.31-4.23% for IPSET-2. The proposed technique had almost equivalent performance with a commercial inspection device, but the time for inspection was reduced to almost one third. We expect that the proposed technique can provide a tool for simple and convenient on-site pre-screening of infusion pumps by nurses to improve patient safety.

A single-pieced, fully air-driven, cuff-inserted pseudo-blood pressure generator for on-site pre-screening test of non-invasive blood pressure monitor by nurses.

BACKGROUND: It is crucial to frequently inspect the proper operation of non-invasive electronic blood pressure monitors in various sites to prevent accidents from inaccurate blood pressure measurements, especially for large-scale hospitals. However, most conventional blood pressure monitor inspection devices are not suitable for such on-site investigation purpose. In this study, we propose a new single-pieced, fully air-driven pseudo blood pressure generator that is suitable for frequent on-site pre-screening tests of the blood pressure monitor by nurses. RESULTS: The proposed model comprises a rigid cylindrical body, two simulated brachial arteries, two air-pumps, an electronic controller, and a pressure sensor. Control algorithm based on polynomial curve fitting was implemented to generate various user-instructed systolic blood pressure and heart-rate conditions automatically. To evaluate the performance and clinical feasibility of the proposed model, various experiments were performed using ten commercial electronic blood pressure monitors. Experimental results demonstrated that the values of the Pearson coefficient between the reference pseudo-blood pressure waveforms and the actually generated pressure waveforms were 0.983, 0.983 and 0.997 at 60, 70 and 80 beats/min, respectively (p < 0.05). Besides, during the experiments using ten commercial blood pressure monitors, the maximum error in average systolic blood pressure was 2.9 mmHg, the maximum standard deviation in average systolic blood pressure was 3.5 mmHg, and the maximum percentage error in average pumping rate was 3.2%, respectively. CONCLUSIONS: We expect that the proposed model can give an easy and comprehensive way for frequent on-site investigations of the blood pressure monitors by nurses, and improve the safety of patients with abnormal blood pressure, especially in most large-scale hospitals.