Abstract Introduction: The real-time measurement of active power delivered to patients during the electrosurgical act is still an engineering challenge. Besides, there is no electrosurgical unit on the market capable of doing it according to the normative requirement. Methods This work presents the design of an electronic structure capable to probe the electrosurgical equipment output electrical signals, using low-costs very common resistors, and High Frequency distortions compensation circuits, and process them to provide an analogue signal proportional to the active power, allowing the knowledge and control of the energy delivered to the biological tissue. The reading circuits and the active power calculation method are presented. The power calculation is performed in two stages. The first one consists of a multiplier circuit that uses the readings voltage and current quantities to determine the instantaneous output power, and the second stage is formed by an integrating circuit which determines the average power value, resulting in a rippled continuous voltage, proportional to the active power delivered to the patient or biological tissue. Results Practical tests of the compensation technical are statistically evaluated by means of linear regressions. Results of 23 tests are summarized in a way to demonstrate de effectiveness of the proposed system. Conclusion Analysis of the results demonstrate the efficiency of the proposed system, whose average error is lower than 5%, and correlating them with the standard IEC 60601-2-2, that regulates the operation of electrosurgery units.

Abstract Introduction: Despite of more than a hundred years of electrosurgery, only a few electrosurgical equipment manufacturers have developed methods to regulate the active power delivered to the patient, usually around an arbitrary setpoint. In fact, no manufacturer has a method to measure the active power actually delivered to the load. Measuring the delivered power and computing it fast enough so as to avoid injury to the organic tissue is challenging. If voltage and current signals can be sampled in time and discretized in the frequency domain, a simple and very fast multiplication process can be used to determine the active power. Methods This paper presents an approach for measuring active power at the output power stage of electrosurgical units with mathematical shortcuts based on a simple multiplication procedure of discretized variables – frequency domain vectors – obtained through Discrete Fourier Transform (DFT) applied on time-sampled voltage and current vectors. Results Comparative results between simulations and a practical experiment are presented – all being in accordance with the requirements of the applicable industry standards. Conclusion An analysis is presented comparing the active power analytically obtained through well-known voltage and current signals against a computational methodology based on vector manipulation using DFT only for time-to-frequency domain transformation. The greatest advantage of this method is to determine the active power of noisy and phased out signals with neither complex DFT or ordinary transform methodologies nor sophisticated computing techniques such as convolution. All results presented errors substantially lower than the thresholds defined by the applicable standards.

RESUMO O objetivo deste estudo é associar a área saudável do pulmão (avaliada pela radiografia) aos dados de mecânica respiratória em crianças no pós-operatório de cirurgia cardíaca, com atelectasia em ventilação mecânica no modo assistido controlado. No total, foram selecionadas 46 crianças, das quais 16 foram excluídas devido às ondas respiratórias irregulares ou à falta de dados da gasometria arterial. Foi analisado um grupo de 30 crianças em modo assistido controlado, sendo que 10 crianças desenvolveram atelectasia. Os dados foram analisados antes e após o início da atelectasia, e a mecânica respiratória foi correlacionada às medidas da área do pulmão. Nas 30 crianças, inicialmente sem complicação pulmonar, foram analisados os dados da gasometria arterial para verificar possíveis mudanças devido aos ciclos assistidos. A atelectasia pode modificar alguns parâmetros da mecânica respiratória. Na associação da área saudável do pulmão com a mecânica respiratória, os resultados da correlação de Spearman mostraram significância estatística entre a área do pulmão com a resistência das vias aéreas (ρ=-0,648 e p=0,043). Os resultados demonstraram que é possível a análise das ondas de mecânica respiratória através da seleção dos ciclos controlados, uma vez que não houve alteração significativa no potencial de hidrogênio iônico. A análise da mecânica respiratória permite verificar a função pulmonar e as possíveis lesões pulmonares. A análise da mecânica respiratória pode ser usada diariamente nessas crianças, permitindo obter informações importantes da função pulmonar. O estudo também mostrou que no modo ventilatório assistido controlado também é possível avaliar a mecânica respiratória.

ABSTRACT The main objective of this study is to associate the healthy area of the lung (evaluated by radiography) with the data of respiratory mechanics in children with atelectasis after cardiac surgery, under mechanical ventilation in the assisted controlled mode. Altogether, 46 children were selected, but 16 were excluded due to irregular respiratory waves or lack of the data on arterial blood gases. A group of 30 children under assisted controlled mode were analyzed, and 10 from this group developed atelectasis. The data were analyzed before and after the onset of atelectasis, and respiratory mechanics was correlated to radiography. We also analyzed the data related to arterial blood gas of these children - who initially had no pulmonary complication - to verify possible changes due to assisted controlled cycles. Atelectasis may modify some parameters of respiratory mechanics. In the association of the healthy area of the lung with the respiratory mechanics, the Spearman correlation results showed statistical significance of the lung area with airway resistance (ρ=−0.648 and p=0.043). Our results show that it is possible to analyze respiratory mechanics waves by selecting controlled cycles in the assisted controlled mode, since we found insignificant changes in potential ionic hydrogen. The analysis of respiratory mechanics allows checking lung function and undesired lung injuries; the analysis of respiratory mechanics can be daily performed in these children to have important information on the pulmonary function. Our research also showed that under the assisted controlled mode is also possible to evaluate respiratory mechanics.

RESUMEN El objetivo de este estudio es asociar la área sana del pulmón (evaluado mediante radiografía) a los datos de mecánica respiratoria en niños en el postoperatorio de cirugía cardiaca, con atelectasia en ventilación mecánica en el modo asistido controlado. En el total, fueron seleccionados 46 niños, de los cuales 16 fueron excluidos debido a las ondas respiratorias irregulares o a la falta de datos de la gasometria arterial. Se analizó un grupo de 30 niños en el modo asistido controlado, de los cuales 10 han desarrollado atelectasia. Los datos fueron analizados antes y después del inicio de la atelectasia, y la mecánica respiratoria se correlacionó a las medidas del área del pulmón. En los 30 niños inicialmente sin complicación pulmonar fueron analizados los datos de la gasometria arterial para comprobar posibles cambios debido a los ciclos asistidos. La atelectasia puede modificar algunos parámetros de la mecánica respiratoria. En la asociación del área saludable del pulmón con la mecánica respiratoria, los resultados de correlación de Spearman demostraron significancia estadística entre el área del pulmón con la resistencia de las vías aéreas (ρ=-0,648 y p=0,043). Los resultados mostraron que es posible el análisis de las ondas de mecánica respiratoria a través de la selección de los ciclos controlados, puesto que no hubo alteración significativa en el potencial de hidrógeno iónico. El análisis de la mecánica respiratoria permite comprobar la función pulmonar y las posibles lesiones pulmonares. Es posible utilizar el análisis de la mecánica respiratoria diariamente en estos niños, permitiendo obtener informaciones importantes de la función pulmonar. El estudio también mostró que en el modo de ventilación controlada es posible evaluar la mecánica respiratoria.