Positive pressure mechanical ventilation (MV) has been utilised in the care of critically ill patients for over 50 years. MV essentially provides for oxygen delivery and carbon dioxide removal by the lungs in patient with respiratory failure or insufficiency from any cause. However, MV can be injurious to the lungs, particularly when high tidal pressures or volumes are used in the management of Acute Respiratory Distress Syndrome (ARDS) or similar acute lung injuries. The hallmark of ARDS is extensive alveolar collapse resulting in hypoxemia and carbon dioxide retention. Application of Positive End Expiratory Pressure (PEEP) is used to prevent derecruitment of alveolar units. Hence, there is a delicate trade-off between applied pressure and volume and benefit of lung recruitment. Current clinical practice lacks a practical method to easily determine the patient specific condition at the bedside without excessive extra tests and intervention. Hence, individual patient treatment is primarily a mixture of "one size- fits-all" protocols and/or the clinician's intuition and experience. A quasi-static, minimal model of lung mechanics is developed based on fundamental lung physiology and mechanics. The model consists of different components that represent a particular mechanism of the lung physiology, and the total lung mechanics are derived by combining them in a physiologically relevant and logical manner. Three system models are developed with varying levels of physiological detail and clinical practicality. The final system model is designed to be directly relevant in current ICU practice using readily available non-invasive data. The model is validated against a physiologically accurate mechanical simulator and clinical data, with both approaches producing clinically significant results. Initial validation using mechanical simulator data showed the model's versatility and ability to capture all physiologically relevant mechanics. Validation using clinical data showed its practicality as a clinical tool, its robustness to noise and/or unmodelled mechanics, and its ability to capture patient specific responses to change in therapy. The model's capability as a predictive clinical tool was assessed with an average prediction error of less than 9% and well within clinical significance. Furthermore, the system model identified parameters that directly indicate and track patient condition, as well as their responsiveness to the treatment, which is a unique and potentially valuable clinical result. Full clinical validation is required, however the model shows significant potential to be fully adopted as a part of standard ventilator treatment in critical care.

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Este trabalho visou mostrar o desenvolvimento de um ventilador pulmonar mecânico, focando principalmente na parte de hardware necessária para que este equipamento pudesse funcionar. Ventilação mecânica é a modalidade da medicina mais importante no cuidado a pacientes criticamente enfermos. O ventilador é um equipamento utilizado principalmente em unidades de terapia intensiva, que basicamente coloca uma mistura de ar e oxigênio para dentro do pulmão de um paciente incapacitado de fazer isto naturalmente, quer seja por força de uma doença que o impossibilita de fazê-lo, ou por uma cirurgia, a qual impossibilitou o movimento do músculo do diafragma para que o ar entrasse no pulmão naturalmente. Este projeto cobriu uma descrição abrangente sobre este ventilador, sua transformação de ar comprimido e oxigênio provenientes de um cilindro em uma mistura controlada de fluxos que entra no pulmão para a inspiração de um volume, ou para atingir uma pressão determinada, e a saída desta mistura, mantendo no pulmão uma pressão também controlada. Foi desenvolvido um protótipo de hardware e firmware para este aparelho, e o intuito foi mostrar o processo de transformação da ideia inicial e as necessidades de projeto em um aparelho testado e certificado para uso no mercado. / This work aimed to present the development of a pulmonary mechanical ventilator, mainly focusing on the hardware part needed in order for this device to work. Mechanical ventilation is the most important medical mode concerning the care of patients that are critically ill. The ventilator is a device very much used in intensive care units (ICUs), and it basically delivers an air and oxygen mixture to the patients lungs that is normally unable to do so naturally, either because the patient is seriously ill that prevents him/her to do so, or due to surgery, in this case prevented the movement of the diaphragm muscle so the air could be naturally delivered to the lung. This work covered a comprehensive description about this ventilator, its transformation of compressed air and oxygen coming from a cylinder in a controlled mixture of flows that enters the lung for the inspiration of a volume, or to achieve a determined pressure, and the output of this mixture, maintaining a controlled pressure in the lung too. A hardware and firmware prototype was developed for this device. The aim was to show the transformation process from the main idea and the need for a project of a tested and certified device to be used in the market.

Background¡G Ventilator-dependent patients have a great and far-reaching impact on families. Their primary caregivers, who are usually the ventilator-dependent patients¡¦ families, have played important roles during the caring process. Those caregivers are burdened with a lot of responsibility and pressure. It is crucial to find out how to assist the caregivers within selected methods of caring and to provide them with suitable needs in order to reduce their psychological burden. Therefore, the purpose of this study is to explore the related factors and to compare the burden and the needs of the primary caregivers in respiratory care ward and home care on long-term ventilator-dependent patients. Design¡G The survey adopts cross-sectional and purposive sampling by using a structured questionnaire to collect information. Both Burden and Needs Questionnaire¡¦s reliability is respectively 0.923 and 0.943; their KMO is 0.828 and 0.829 ; their Expert Validity (CVI) is 0.88 and 0.91. The questionnaire has reached the ideal value of reliability and validity. The sampling subjects are from respiratory care ward and home care centers in southern Taiwan. Total 260 out of 280 questionnaires are returned (the response rate has reached 92.9%) and there are 241 valid samples. The questionnaires are used for data collection and are divided into four sections; ¡§patient basic information¡¨ , ¡§family basic information¡¨, ¡§caregiver burden scale¡¨, and ¡§caregiver need scale ¡¨. The collected data is analyzed with descriptive statistics-test, one-way ANOVA, Pearson¡¦s correlation and multiple regressions by using SPSS Windows version 12.0. Result¡G (1) Patients from Home-care centre are normally younger in comparison with the patients from respiratory care wards; their average usage of mechanical ventilator is 30.98 month longer; they tend to have more conscious and tracheotomy patients. According to the demography, these two groups of the patients have a significant difference. (2) The average age of primary home care and respiratory care ward caregivers is 50¡ã52; most of them are female; most of the care givers are the patients¡¦ children. (3) "Physiological burdens" and "physiological needs" of home care centers caregivers are greater than the caregivers in respiratory care ward. They have reached a significant difference in statistic. (4) The primary caregivers have a declining health, and their workload and demands are increasing. (5) There is a significant positive correlation between the primary caregivers¡¦ burden and needs. (6) Base on the numbers of admitting to the ICU, the hospital and the current health status of the primary caregivers; the workload is predictable. Conclusion¡G Hopefully the result of this study can provide the Government to formulate a long-term-care insurance. Focus on providing the services to different needs for the caregivers; reduce the caregivers¡¦ burden on caring the mechanical ventilator patients. Also, to provide health care workers and respiratory therapists to implement on transferring patients to respiratory care ward and to offer further health education for the primary caregivers of home care centers.

Este trabalho visou mostrar o desenvolvimento de um ventilador pulmonar mecânico, focando principalmente na parte de hardware necessária para que este equipamento pudesse funcionar. Ventilação mecânica é a modalidade da medicina mais importante no cuidado a pacientes criticamente enfermos. O ventilador é um equipamento utilizado principalmente em unidades de terapia intensiva, que basicamente coloca uma mistura de ar e oxigênio para dentro do pulmão de um paciente incapacitado de fazer isto naturalmente, quer seja por força de uma doença que o impossibilita de fazê-lo, ou por uma cirurgia, a qual impossibilitou o movimento do músculo do diafragma para que o ar entrasse no pulmão naturalmente. Este projeto cobriu uma descrição abrangente sobre este ventilador, sua transformação de ar comprimido e oxigênio provenientes de um cilindro em uma mistura controlada de fluxos que entra no pulmão para a inspiração de um volume, ou para atingir uma pressão determinada, e a saída desta mistura, mantendo no pulmão uma pressão também controlada. Foi desenvolvido um protótipo de hardware e firmware para este aparelho, e o intuito foi mostrar o processo de transformação da ideia inicial e as necessidades de projeto em um aparelho testado e certificado para uso no mercado. / This work aimed to present the development of a pulmonary mechanical ventilator, mainly focusing on the hardware part needed in order for this device to work. Mechanical ventilation is the most important medical mode concerning the care of patients that are critically ill. The ventilator is a device very much used in intensive care units (ICUs), and it basically delivers an air and oxygen mixture to the patients lungs that is normally unable to do so naturally, either because the patient is seriously ill that prevents him/her to do so, or due to surgery, in this case prevented the movement of the diaphragm muscle so the air could be naturally delivered to the lung. This work covered a comprehensive description about this ventilator, its transformation of compressed air and oxygen coming from a cylinder in a controlled mixture of flows that enters the lung for the inspiration of a volume, or to achieve a determined pressure, and the output of this mixture, maintaining a controlled pressure in the lung too. A hardware and firmware prototype was developed for this device. The aim was to show the transformation process from the main idea and the need for a project of a tested and certified device to be used in the market.

Auto-PEEP is auto positive end-expiratory pressure due to excessive amounts of alveolar gas produced by sustained recurrent incomplete exhalation. Incomplete exhalation occurs when the exhaled breath never reaches a flow rate of 0 L/min. The objective of this dissertation is to develop an automated detection system of auto-PEEP through incomplete exhalation as revealed by ventilator graphics for mechanically ventilated adults. Auto-PEEP can cause adverse effects if allowed to linger and if not quickly identified. An automated detection system will be instrumental in helping to quickly identify auto-PEEP. A computerized algorithm was developed to detect incomplete exhalation based on the following three parameters:1) Foi, was used to represent the value of the flow at the onset of inhalation, 2) ∆T, was used to represent the value of time difference between onset inhalation to the 0 L/min mark, and 3) slope threshold, a value set for the slope of change of flow over ∆T. Optimum parameters of the algorithm were achieved for Foi = -3 L/min, ∆T = 0.2 s, and slope threshold = 90 L-s/min. A novel data set was introduced to validate the algorithm, yielding no significant difference in true positive rates (t = 1.5, df = 12.402, p-value = 0.1408) and false positive rates (t = 1.9, df = 16.765, p-value = 0.0725) as outcomes for two-tailed t-tests comparing the novel and old data set. To determine the relationship between auto-PEEP and detection of sustained incomplete exhalation, a correlation of a linear model of the novel data set between auto-PEEP and the percentage of incomplete exhalation detection out of the existing breaths (index) was investigated. A linear model should interpret the index value that corresponds to significant auto-PEEP presence; unfortunately, no significant linear model was found between incomplete exhalation index and auto-PEEP (F1,62 = 1.67, p-value = 0.2010). However, there was a relationship between the intrinsic PEEP values and the incomplete exhalation index as functions of time. The automated detection algorithm produced by this work provides a non-invasive method of automatically detecting auto-PEEP.

Introdução: A formação de atelectasia durante a indução anestésica pode ser um dos fatores responsáveis pela ocorrência de complicações pulmonares pós-operatórias (CPP). A aplicação de pressão positiva expiratória ao final da expiração (PEEP), uso criterioso de altas frações inspiradas de oxigênio e a utilização de manobras de recrutamento alveolar no período intra-operatório são recursos utilizados para a prevenção de atelectasia em procedimentos anestésicos. O objetivo deste estudo foi avaliar o modelo de ventilação mecânica adotado em procedimentos anestésicos de longa duração e suas correlações com as complicações pulmonares pós-operatórias. Métodos: Foram avaliadas em estudo observacional as cirurgias com mais de cinco horas de duração. No início do procedimento anestésico, na sala de cirurgia e após o seu término, na unidade de terapia intensiva, os parâmetros ventilatórios utilizados foram anotados e correlacionados com os achados das radiografias torácicas e saturação periférica de oxigênio (SpO2) em ar ambiente. Resultados: Cento e vinte e um pacientes foram observados. O tempo total de anestesia 499,4 ± 159,8 minutos. O volume corrente (VC) determinado no período intraoperatório foi 8,09 ± 2,15 mL/kg e a PEEP utilizada de 3,05 ± 2,31 cmH2O. Houve diferença para a mediana da SpO2 em ar ambiente (96% [95-97] vs 95% [92-96], p <0,001) comparando os períodos pré e pós-operatório. A freqüência de pacientes que apresentaram atelectasia nas radiografias de tórax do período pós-operatório (38,8%) foi significantemente maior que a do período pré-operatório (0%), x2=32,259. Não foi encontrado correlação entre os achados e o tempo de anestesia (p=0,708); a PEEP intra-operatória (p=0,296); tempo de permanência com suporte ventilatório mecânico no pósoperatório (p = 0,146) e tabagismo (p = 0,563). Conclusões: No período intra-operatório o PEEP utilizado em procedimentos de longa duração é baixo. Ocorre queda na SpO2 e aumento na incidência de atelectasia no período pós-operatório em comparação com o pré-operatório. São necessários outros estudos para melhor avaliação dos fatores responsáveis / Introduction: The formation of the atelectasis during the induction of the anesthesia can be one of the factors involved in the occurrence of postoperative pulmonary complications (PPCs). The application of the positive end-expiratory pressure (PEEP), low inpiratory concentrations of oxygen and the alveolar recruitment maneuvers perform in the intraoperative period are approaches used in the prevention of atelectasis in the anesthesia procedures. The objective of this study was to evaluate, in prospective observational study, the pattern of mechanical ventilatory assistence during longer anesthesia procedures and its correlations with the PPCs. Methods: The surgeries procedures longer than five hours have been evaluated in observational study. At the beginning of the anesthesia procedure, in the operatory room and after its terminus, in the intensive care unit, the mechanical ventilation parameters were determined and correlated with the findings in the chest x-rays and peripheral oxygen saturation (SpO2) in room air. Results: One hundred twenty one patients have been observed. The total time of anesthesia was 499,4 ± 159,8 minutes. The tidal volume (VT) in the intraoperative period was 8,09 ± 2,15 mL/kg and the PEEP used was 3,05 ± 2,31 cmH2O. There was a difference for the median of the SpO2 in room air (96% [95-97] vs 95% [92-96], p <0,001) comparing the pre and postoperative periods. The frequency of patients who had presented atelectasis in the chest x-rays of the postoperative period (38,8%) was significantly higher than the preoperative period (0%), x2=32,259. No correlation was found among these findings and the anesthesia time (p=0,708); the intraoperative PEEP used (p=0,296); time with mechanical ventilatory support in the postoperative period (p = 0,146) and smoking habits (p = 0,563). Conclusions: In the intraoperative period, the PEEP is low in longer procedures. The SpO2 decreases and the incidence of the atelectasis increases in the postoperative period, when compared with the preoperative one. Other researches are required for better evaluation of the factors related for the development of the PPCs

Introdução: A formação de atelectasia durante a indução anestésica pode ser um dos fatores responsáveis pela ocorrência de complicações pulmonares pós-operatórias (CPP). A aplicação de pressão positiva expiratória ao final da expiração (PEEP), uso criterioso de altas frações inspiradas de oxigênio e a utilização de manobras de recrutamento alveolar no período intra-operatório são recursos utilizados para a prevenção de atelectasia em procedimentos anestésicos. O objetivo deste estudo foi avaliar o modelo de ventilação mecânica adotado em procedimentos anestésicos de longa duração e suas correlações com as complicações pulmonares pós-operatórias. Métodos: Foram avaliadas em estudo observacional as cirurgias com mais de cinco horas de duração. No início do procedimento anestésico, na sala de cirurgia e após o seu término, na unidade de terapia intensiva, os parâmetros ventilatórios utilizados foram anotados e correlacionados com os achados das radiografias torácicas e saturação periférica de oxigênio (SpO2) em ar ambiente. Resultados: Cento e vinte e um pacientes foram observados. O tempo total de anestesia 499,4 ± 159,8 minutos. O volume corrente (VC) determinado no período intraoperatório foi 8,09 ± 2,15 mL/kg e a PEEP utilizada de 3,05 ± 2,31 cmH2O. Houve diferença para a mediana da SpO2 em ar ambiente (96% [95-97] vs 95% [92-96], p <0,001) comparando os períodos pré e pós-operatório. A freqüência de pacientes que apresentaram atelectasia nas radiografias de tórax do período pós-operatório (38,8%) foi significantemente maior que a do período pré-operatório (0%), x2=32,259. Não foi encontrado correlação entre os achados e o tempo de anestesia (p=0,708); a PEEP intra-operatória (p=0,296); tempo de permanência com suporte ventilatório mecânico no pósoperatório (p = 0,146) e tabagismo (p = 0,563). Conclusões: No período intra-operatório o PEEP utilizado em procedimentos de longa duração é baixo. Ocorre queda na SpO2 e aumento na incidência de atelectasia no período pós-operatório em comparação com o pré-operatório. São necessários outros estudos para melhor avaliação dos fatores responsáveis / Introduction: The formation of the atelectasis during the induction of the anesthesia can be one of the factors involved in the occurrence of postoperative pulmonary complications (PPCs). The application of the positive end-expiratory pressure (PEEP), low inpiratory concentrations of oxygen and the alveolar recruitment maneuvers perform in the intraoperative period are approaches used in the prevention of atelectasis in the anesthesia procedures. The objective of this study was to evaluate, in prospective observational study, the pattern of mechanical ventilatory assistence during longer anesthesia procedures and its correlations with the PPCs. Methods: The surgeries procedures longer than five hours have been evaluated in observational study. At the beginning of the anesthesia procedure, in the operatory room and after its terminus, in the intensive care unit, the mechanical ventilation parameters were determined and correlated with the findings in the chest x-rays and peripheral oxygen saturation (SpO2) in room air. Results: One hundred twenty one patients have been observed. The total time of anesthesia was 499,4 ± 159,8 minutes. The tidal volume (VT) in the intraoperative period was 8,09 ± 2,15 mL/kg and the PEEP used was 3,05 ± 2,31 cmH2O. There was a difference for the median of the SpO2 in room air (96% [95-97] vs 95% [92-96], p <0,001) comparing the pre and postoperative periods. The frequency of patients who had presented atelectasis in the chest x-rays of the postoperative period (38,8%) was significantly higher than the preoperative period (0%), x2=32,259. No correlation was found among these findings and the anesthesia time (p=0,708); the intraoperative PEEP used (p=0,296); time with mechanical ventilatory support in the postoperative period (p = 0,146) and smoking habits (p = 0,563). Conclusions: In the intraoperative period, the PEEP is low in longer procedures. The SpO2 decreases and the incidence of the atelectasis increases in the postoperative period, when compared with the preoperative one. Other researches are required for better evaluation of the factors related for the development of the PPCs