Impact on the ability of healthcare professionals to correctly identify patient-ventilator asynchronies of the simultaneous visualization of estimated muscle pressure curves on the ventilator display: a randomized study (Pmus study).

BACKGROUND: Patient-ventilator asynchronies are usually detected by visual inspection of ventilator waveforms but with low sensitivity, even when performed by experts in the field. Recently, estimation of the inspiratory muscle pressure (Pmus) waveforms through artificial intelligence algorithm has been proposed (Magnamed®, São Paulo, Brazil). We hypothesized that the display of these waveforms could help healthcare providers identify patient-ventilator asynchronies. METHODS: A prospective single-center randomized study with parallel assignment was conducted to assess whether the display of the estimated Pmus waveform would improve the correct identification of asynchronies in simulated clinical scenarios. The primary outcome was the mean asynchrony detection rate (sensitivity). Physicians and respiratory therapists who work in intensive care units were randomized to control or intervention group. In both groups, participants analyzed pressure and flow waveforms of 49 different scenarios elaborated using the ASL-5000 lung simulator. In the intervention group the estimated Pmus waveform was displayed in addition to pressure and flow waveforms. RESULTS: A total of 98 participants were included, 49 per group. The sensitivity per participant in identifying asynchronies was significantly higher in the Pmus group (65.8 ± 16.2 vs. 52.94 ± 8.42, p < 0.001). This effect remained when stratifying asynchronies by type. CONCLUSIONS: We showed that the display of the Pmus waveform improved the ability of healthcare professionals to recognize patient-ventilator asynchronies by visual inspection of ventilator tracings. These findings require clinical validation. TRIAL REGISTRATION: ClinicalTrials.gov: NTC05144607. Retrospectively registered 3 December 2021.

Religiosity and Religious Coping in Patients with COPD: A Cross-Sectional Comparison Between Brazil and the Netherlands and Associations with Physical and Psychological Health.

This study aimed to compare religiosity and religious coping (RC) between Brazilian and Dutch patients with chronic obstructive pulmonary disease (COPD) and to examine associations with physical and psychological health. Religiosity, RC, and physical and psychological health were cross-sectionally assessed in 161 patients with COPD (74 from Brazil and 87 from the Netherlands). Brazilian participants showed the greatest religiosity (p < 0.05), and weak correlations were observed between religiosity/RC and exercise capacity and quality of life (p < 0.05 for all analyses). Brazilian patients with COPD had higher religiosity than Dutch patients, and religiosity correlated with functional exercise capacity and quality of life.

Sexuality and Associated Factors in Chronic Obstructive Pulmonary Disease (COPD) Patients Attending a Referral Hospital in Northeastern Brazil.

OBJECTIVE: The aim of this study was to evaluate sexual function in male and female COPD (chronic obstructive pulmonary disease) patients and identify associated factors. Methods: This is a cross-sectional study on 52 COPD patients treated at an outpatient pneumology service of a referral hospital in Northeastern Brazil. Information was collected on demographic, clinical and spirometric variables and exercise capacity. The following instruments and scores were used: modified Medical Research Council (mMRC) for dyspnea, SF-36 for quality of life (QoL), the Beck Depression and Anxiety Inventory, Male and Female Sexual Quotient. Results: Sexual function was satisfactory/excellent in 17% (9/52) and poor/absent in 82% (43/52). Patients with poor/absent sexual function tended to have lower scores on the domain mental health summary score of SF-36 (p = 0.007) and higher anxiety and depression scores than patients with satisfactory/excellent sexual function (p = 0.02 and p = 0.01). In the multivariate analysis, patients with high depression scores displayed a greater likelihood of poor/absent sexual function (OR = 1.13; 95% CI = 1.02-1.25). Conclusion: COPD patients presented a high rate of sexual dysfunction and compromised sexuality was associated with depression.

Helping students to understand physiological aspects of regional distribution of ventilation in humans: a experience from the electrical impedance tomography.

Undergraduate biomedical students often have difficulties in understanding basic concepts of respiratory physiology, particularly respiratory mechanics. In this study, we report the use of electrical impedance tomography (EIT) to improve and consolidate the knowledge about physiological aspects of normal regional distribution of ventilation in humans. Initially, we assessed the previous knowledge of a group of medical students ( n = 39) about regional differences in lung ventilation. Thereafter, we recorded the regional distribution of ventilation through surface electrodes on a healthy volunteer adopting four different decubitus positions: supine, prone, and right and left lateral. The recordings clearly showed greater pulmonary ventilation in the dependent lung, mainly in the lateral decubitus. Considering the differences in pulmonary ventilation between right and left lateral decubitus, only 33% of students were able to notice it correctly beforehand. This percentage increased to 84 and 100%, respectively ( P < 0.01), after the results of the ventilation measurements obtained with EIT were examined and discussed. A self-assessment questionnaire showed that students considered the practical activity as an important tool to assist in the understanding of the basic concepts of respiratory mechanics. Experimental demonstration of the physiological variations of regional lung ventilation in volunteers by using EIT is feasible, effective, and stimulating for undergraduate medical students. Therefore, this practical activity may help faculty and students to overcome the challenges in the field of respiratory physiology learning.

The Effects of Prone Position Ventilation on Experimental Mild Acute Lung Injury Induced by Intraperitoneal Lipopolysaccharide Injection in Rats.

INTRODUCTION: The benefits of prone position ventilation are well demonstrated in the severe forms of acute respiratory distress syndrome, but not in the milder forms. We investigated the effects of prone position on arterial blood gases, lung inflammation, and histology in an experimental mild acute lung injury (ALI) model. METHODS: ALI was induced in Wistar rats by intraperitoneal Escherichia coli lipopolysaccharide (LPS, 5 mg/kg). After 24 h, the animals with PaO2/FIO2 between 200 and 300 mmHg were randomized into 2 groups: prone position (n = 6) and supine position (n = 6). Both groups were compared with a control group (n = 5) that was ventilated in the supine position. All of the groups were ventilated for 1 h with volume-controlled ventilation mode (tidal volume = 6 ml/kg, respiratory rate = 80 breaths/min, positive end-expiratory pressure = 5 cmH2O, inspired oxygen fraction = 1) RESULTS: Significantly higher lung injury scores were observed in the LPS-supine group compared to the LPS-prone and control groups (0.32 ± 0.03; 0.17 ± 0.03 and 0.13 ± 0.04, respectively) (p < 0.001), mainly due to a higher neutrophil infiltration level in the interstitial space and more proteinaceous debris that filled the airspaces. Similar differences were observed when the gravity-dependent lung regions and non-dependent lung regions were analyzed separately (p < 0.05). The BAL neutrophil content was also higher in the LPS-supine group compared to the LPS-prone and control groups (p < 0.05). There were no significant differences in the wet/dry ratio and gas exchange levels. CONCLUSIONS: In this experimental extrapulmonary mild ALI model, prone position ventilation for 1 h, when compared with supine position ventilation, was associated with lower lung inflammation and injury.

ELMO CPAP: an innovative type of ventilatory support for COVID-19-related acute respiratory distress syndrome.

OBJECTIVE: To assess whether the use of ELMO, a helmet for noninvasive ventilation created in Brazil, had a positive impact on the prognosis of patients with hypoxemic respiratory failure caused by severe COVID-19. METHODS: This is a retrospective study of 50 critically ill COVID-19 patients. Epidemiological, clinical, and laboratory data were collected on ICU admission, as well as before, during, and after ELMO use. Patients were divided into two groups (success and failure) according to the outcome. RESULTS: ELMO use improved oxygenation parameters such as Pao2, Fio2, and the Pao2/Fio2 ratio, and this contributed to a gradual reduction in Fio2, without an increase in CO2, as determined by arterial blood gas analysis. Patients in the success group had significantly longer survival (p < 0.001), as determined by the Kaplan-Meier analysis, less need for intubation (p < 0.001), fewer days of hospitalization, and a lower incidence of acute kidney injury in comparison with those in the failure group. CONCLUSIONS: The significant improvement in oxygenation parameters, the longer survival, as reflected by the reduced need for intubation and by the mortality rate, and the absence of acute kidney injury suggest that the ELMO CPAP system is a promising tool for treating ARDS and similar clinical conditions.

Influences of assisted breathing and mechanical ventilator settings on tidal volume and alveolar pressures in acute respiratory distress syndrome: a bench study. / Influência da ventilação assistida e dos ajustes do ventilador mecânico sobre o volume corrente e as pressões alveolares na síndrome do desconforto respiratório agudo: um estudo de bancada.

OBJECTIVE: To evaluate the influences of respiratory muscle efforts and respiratory rate setting in the ventilator on tidal volume and alveolar distending pressures at end inspiration and expiration in volume-controlled ventilation and pressure-controlled ventilation modes in acute respiratory distress syndrome. METHODS: An active test lung (ASL 5000™) connected to five intensive care unit ventilators was used in a model of acute respiratory distress syndrome. Respiratory muscle efforts (muscle pressure) were configured in three different ways: no effort (muscle pressure: 0cmH2O); inspiratory efforts only (muscle pressure:-5cmH2O, neural inspiratory time of 0.6s); and both inspiratory and expiratory muscle efforts (muscle pressure:-5/+5cmH2O). Volume-controlled and pressure-controlled ventilation modes were set to deliver a target tidal volume of 420mL and positive end-expiratory pressure of 10cmH2O. The tidal volume delivered to the lungs, alveolar pressures at the end of inspiration, and alveolar pressures at end expiration were evaluated. RESULTS: When triggered by the simulated patient, the median tidal volume was 27mL lower than the set tidal volume (range-63 to +79mL), and there was variation in alveolar pressures with a median of 25.4cmH2O (range 20.5 to 30cmH2O). In the simulated scenarios with both spontaneous inspiratory and expiratory muscle efforts and with a mandatory respiratory rate lower than the simulated patient's efforts, the median tidal volume was higher than controlled breathing. CONCLUSION: Adjusting respiratory muscle effort and pulmonary ventilator respiratory rate to a value above the patient's respiratory rate in assisted/controlled modes generated large variations in tidal volume and pulmonary pressures, while the controlled mode showed no variations in these outcomes.

OBJETIVO: Avaliar a influência dos esforços musculares respiratórios e do ajuste da frequência respiratória no ventilador sobre o volume corrente e as pressões de distensão alveolar ao final da inspiração e expiração com ventilação sob os modos controle por volume e controle por pressão na síndrome do desconforto respiratório agudo. MÉTODOS: Utilizou-se um simulador mecânico de pulmão (ASL 5000™) conectado a cinco tipos de ventiladores utilizados em unidade de terapia intensiva, em um modelo de síndrome do desconforto respiratório agudo. Os esforços musculares respiratórios (pressão muscular) foram configurados de três formas distintas: sem esforço (pressão muscular: 0cmH2O), apenas esforços inspiratórios (pressão muscular: - 5cmH2O, tempo inspiratório neural de 0,6 segundos) e esforços musculares inspiratórios e expiratórios (pressão muscular:-5/+5cmH2O). Foram configuradas ventilação sob os modos controle por volume e ventilação com controle por pressão para oferecer um volume corrente de 420mL e pressão positiva expiratória final de 10cmH2O. Avaliaram-se o volume corrente fornecido aos pulmões, as pressões alveolares no final da inspiração e as pressões alveolares no final da expiração. RESULTADOS: Quando disparado pelo paciente simulado, o volume corrente mediano foi 27mL menor do que o volume corrente ajustado (variação-63 a +79mL), e ocorreu uma variação nas pressões alveolares com mediana de 25,4cmH2O (faixa de 20,5 a 30cmH2O). Nos cenários simulados com esforço muscular tanto inspiratório quanto expiratório e com frequência respiratória mandatória inferior à dos esforços do paciente simulado, o volume corrente mediano foi maior com ventilação controlada. CONCLUSÃO: O ajuste do esforço muscular respiratório e da frequência respiratória no ventilador em um valor acima da frequência respiratória do paciente nos modos de ventilação assistida/controlada gerou maiores variações no volume corrente e nas pressões pulmonares, enquanto o modo controlado não mostrou variações nesses desfechos.

ELMO, a new helmet interface for CPAP to treat COVID-19-related acute hypoxemic respiratory failure outside the ICU: a feasibility study.

OBJECTIVE: To assess the feasibility of using a new helmet interface for CPAP, designated ELMO, to treat COVID-19-related acute hypoxemic respiratory failure (AHRF) outside the ICU. METHODS: This was a proof-of-concept study involving patients with moderate to severe AHRF secondary to COVID-19 admitted to the general ward of a public hospital. The intervention consisted of applying CPAP via the ELMO interface integrated with oxygen and compressed air flow meters (30 L/min each) and a PEEP valve (CPAP levels = 8-10 cmH2O), forming the ELMOcpap system. The patients were monitored for cardiorespiratory parameters, adverse events, and comfort. RESULTS: Ten patients completed the study protocol. The ELMOcpap system was well tolerated, with no relevant adverse effects. Its use was feasible outside the ICU for a prolonged amount of time and was shown to be successful in 60% of the patients. A CPAP of 10 cmH2O with a total gas flow of 56-60 L/min improved oxygenation after 30-to 60-min ELMOcpap sessions, allowing a significant decrease in estimated FIO2 (p = 0.014) and an increase in estimated PaO2/FIO2 ratio (p = 0.008) within the first hour without CO2 rebreathing. CONCLUSIONS: The use of ELMOcpap has proven to be feasible and effective in delivering high-flow CPAP to patients with COVID-19-related AHRF outside the ICU. There were no major adverse effects, and ELMO was considered comfortable. ELMOcpap sessions significantly improved oxygenation, reducing FIO2 without CO2 rebreathing. The overall success rate was 60% in this pilot study, and further clinical trials should be carried out in the future.(ClinicalTrials.gov identifier: NCT04470258 [http://www.clinicaltrials.gov/]).

Protective mechanical ventilation in patients with risk factors for ARDS: prospective cohort study.

OBJECTIVE: To evaluate the association that protective mechanical ventilation (MV), based on VT and maximum distending pressure (MDP), has with mortality in patients at risk for ARDS. METHODS: This was a prospective cohort study conducted in an ICU and including 116 patients on MV who had at least one risk factor for the development of ARDS. Ventilatory parameters were collected twice a day for seven days, and patients were divided into two groups (protective MV and nonprotective MV) based on the MDP (difference between maximum airway pressure and PEEP) or VT. The outcome measures were 28-day mortality, ICU mortality, and in-hospital mortality. The risk factors associated with the adoption of nonprotective MV were also assessed. RESULTS: Nonprotective MV based on VT and MDP was applied in 49 (42.2%) and 38 (32.8%) of the patients, respectively. Multivariate Cox regression showed that protective MV based on MDP was associated with lower in-hospital mortality (hazard ratio = 0.37; 95% CI: 0.19-0.73) and lower ICU mortality (hazard ratio = 0.40; 95% CI: 0.19-0.85), after adjustment for age, Simplified Acute Physiology Score 3, and vasopressor use, as well as the baseline values for PaO2/FiO2 ratio, PEEP, pH, and PaCO2. These associations were not observed when nonprotective MV was based on the VT. CONCLUSIONS: The MDP seems to be a useful tool, better than VT, for adjusting MV in patients at risk for ARDS.

Acute effects of noninvasive ventilation on sleep physiology in patients with moderate to severe stable chronic obstructive pulmonary disease: a pilot study.

OBJECTIVE/BACKGROUND: Changes in sleep architecture in patients with Chronic Obstructive Pulmonary Disease (COPD) can be explained by a combination of physiological changes in breathing during sleep, with impairment of respiratory mechanics and reduction of arterial oxygenation. This study aimed to evaluate the acute effects of noninvasive ventilation (NIV) - compared to spontaneous breathing - on sleep latency and stages, and on the occurrence of sleep-related respiratory events, nocturnal hypoxemia, and changes in heart rate (HR) in patients with moderate to severe stable COPD. PATIENTS/METHODS: Patients completed two polysomnography (PSG) studies: one during spontaneous breathing and one while receiving NIV in bilevel mode and with backup respiratory rate (RR.) setting. Sleepware G3 software was used for the analysis of PSG and pressure, volume, and ventilator flow curves × time. RESULTS: Participants were 10 female patients with a mean age of 68.1 ± 10.2 years. NIV during sleep decreased sleep onset latency (17 ± 18.8 min vs 46.8 ± 39.5 min; p = 0.02), increased REM sleep time (41.2 ± 24.7 min vs 19.7 ± 21.7 min; p = 0.03), and decreased the obstructive apnea index (OAI) (0 vs 8.7 ± 18.8; p = 0.01). Lower mean HR (66.6 ± 4.1 bpm vs 70.6 ± 5.9 bpm; p = 0.03) and lower maximum HR (84.1 ± 7.3 bpm vs 91.6 ± 7.8 bpm; p = 0.03) were observed in PSG with NIV. CONCLUSIONS: The use of NIV in patients with moderate to severe stable COPD while they were sleeping increased REM sleep time and decreased sleep onset latency, the number of obstructive respiratory events, and the mean and maximum HR.

Patient-ventilator asynchrony.

Patient-v entilator asynchrony (PVA) is a mismatch between the patient, regarding time, flow, volume, or pressure demands of the patient respiratory system, and the ventilator, which supplies such demands, during mechanical ventilation (MV). It is a common phenomenon, with incidence rates ranging from 10% to 85%. PVA might be due to factors related to the patient, to the ventilator, or both. The most common PVA types are those related to triggering, such as ineffective effort, auto-triggering, and double triggering; those related to premature or delayed cycling; and those related to insufficient or excessive flow. Each of these types can be detected by visual inspection of volume, flow, and pressure waveforms on the mechanical ventilator display. Specific ventilatory strategies can be used in combination with clinical management, such as controlling patient pain, anxiety, fever, etc. Deep sedation should be avoided whenever possible. PVA has been associated with unwanted outcomes, such as discomfort, dyspnea, worsening of pulmonary gas exchange, increased work of breathing, diaphragmatic injury, sleep impairment, and increased use of sedation or neuromuscular blockade, as well as increases in the duration of MV, weaning time, and mortality. Proportional assist ventilation and neurally adjusted ventilatory assist are modalities of partial ventilatory support that reduce PVA and have shown promise. This article reviews the literature on the types and causes of PVA, as well as the methods used in its evaluation, its potential implications in the recovery process of critically ill patients, and strategies for its resolution.

ELMO CPAP: an innovative type of ventilatory support for COVID-19-related acute respiratory distress syndrome / ELMO-CPAP: um suporte ventilatório inovador para síndrome do desconforto respiratório agudo por COVID-19

ABSTRACT Objective: To assess whether the use of ELMO, a helmet for noninvasive ventilation created in Brazil, had a positive impact on the prognosis of patients with hypoxemic respiratory failure caused by severe COVID-19. Methods: This is a retrospective study of 50 critically ill COVID-19 patients. Epidemiological, clinical, and laboratory data were collected on ICU admission, as well as before, during, and after ELMO use. Patients were divided into two groups (success and failure) according to the outcome. Results: ELMO use improved oxygenation parameters such as Pao2, Fio2, and the Pao2/Fio2 ratio, and this contributed to a gradual reduction in Fio2, without an increase in CO2, as determined by arterial blood gas analysis. Patients in the success group had significantly longer survival (p < 0.001), as determined by the Kaplan-Meier analysis, less need for intubation (p < 0.001), fewer days of hospitalization, and a lower incidence of acute kidney injury in comparison with those in the failure group. Conclusions: The significant improvement in oxygenation parameters, the longer survival, as reflected by the reduced need for intubation and by the mortality rate, and the absence of acute kidney injury suggest that the ELMO CPAP system is a promising tool for treating ARDS and similar clinical conditions.

RESUMO Objetivo: Avaliar se o uso do ELMO, um capacete para ventilação não invasiva criado no Brasil, teve impacto positivo no prognóstico de pacientes com insuficiência respiratória hipoxêmica por COVID-19 grave. Métodos: Estudo retrospectivo com 50 pacientes críticos com COVID-19. Dados epidemiológicos, clínicos e laboratoriais foram coletados na admissão na UTI e antes, durante e após o uso do ELMO. Os pacientes foram divididos em dois grupos (sucesso e falha) de acordo com o desfecho. Resultados: O uso do ELMO melhorou parâmetros de oxigenação como Pao2, Fio2 e relação Pao2/Fio2, e isso contribuiu para uma redução gradual da Fio2, sem aumento do CO2, conforme determinado pela gasometria arterial. Os pacientes do grupo sucesso apresentaram sobrevida significativamente maior (p < 0,001), conforme determinado pela análise de Kaplan-Meier, menor necessidade de intubação (p < 0,001), menos dias de hospitalização e menor incidência de lesão renal aguda em comparação com os do grupo falha. Conclusões: A significativa melhora nos parâmetros de oxigenação, a maior sobrevida, refletida pela menor necessidade de intubação e pela taxa de mortalidade, e a ausência de lesão renal aguda sugerem que o sistema ELMO CPAP é uma ferramenta promissora para o tratamento da SDRA e de condições clínicas semelhantes.

Influence of the ventilatory mode on acute adverse effects and facial thermography after noninvasive ventilation.

OBJECTIVE:: To compare the incidence and intensity of acute adverse effects and the variation in the temperature of facial skin by thermography after the use of noninvasive ventilation (NIV). METHODS:: We included 20 healthy volunteers receiving NIV via oronasal mask for 1 h. The volunteers were randomly divided into two groups according to the ventilatory mode: bilevel positive airway pressure (BiPAP) or continuous positive airway pressure (CPAP). Facial thermography was performed in order to determine the temperature of the face where it was in contact with the mask and of the nasal dorsum at various time points. After removal of the mask, the volunteers completed a questionnaire about adverse effects of NIV. RESULTS:: The incidence and intensity of acute adverse effects were higher in the individuals receiving BiPAP than in those receiving CPAP (16.1% vs. 5.6%). Thermographic analysis showed a significant cooling of the facial skin in the two regions of interest immediately after removal of the mask. The more intense acute adverse effects occurred predominantly among the participants in whom the decrease in the mean temperature of the nasal dorsum was lower (14.4% vs. 7.2%). The thermographic visual analysis of the zones of cooling and heating on the face identified areas of hypoperfusion or reactive hyperemia. CONCLUSIONS:: The use of BiPAP mode was associated with a higher incidence and intensity of NIV-related acute adverse effects. There was an association between acute adverse effects and less cooling of the nasal dorsum immediately after removal of the mask. Cutaneous thermography can be an additional tool to detect adverse effects that the use of NIV has on facial skin. OBJETIVO:: Comparar a incidência e a intensidade de efeitos adversos agudos e a variação da temperatura da pele da face através da termografia após a aplicação de ventilação não invasiva (VNI). MÉTODOS:: Foram incluídos 20 voluntários sadios, de ambos os gêneros, submetidos à VNI com máscara oronasal por 1 h e divididos aleatoriamente em dois grupos de acordo com o modo ventilatório: bilevel positive airway pressure (BiPAP) ou continuous positive airway pressure (CPAP). A termografia da face foi realizada para determinar a temperatura na região de contato da máscara e no dorso do nariz em momentos diferentes. Os voluntários preencheram um questionário de efeitos adversos após a retirada da VNI. RESULTADOS:: A incidência e a intensidade dos efeitos adversos agudos foram maiores naqueles submetidos a BiPAP em relação aos submetidos a CPAP (16,1% vs. 5,6%). A análise termográfica evidenciou um esfriamento significativo da pele facial nas duas regiões de estudo imediatamente após a retirada da máscara. Os efeitos adversos agudos em maior intensidade ocorreram predominantemente no grupo de participantes cuja redução da temperatura média no dorso do nariz foi menor (14,4% vs. 7,2%). A análise visual termográfica de zonas de esfriamento e aquecimento na face identificou regiões de hipoperfusão ou hiperemia reativa. CONCLUSÕES:: O uso do modo BiPAP associou-se a maior incidência e intensidade de efeitos adversos agudos associados à VNI. Houve associação entre efeitos adversos agudos e menor esfriamento da pele do dorso do nariz imediatamente após a retirada da máscara. A termografia cutânea pode ser uma ferramenta adicional na detecção de efeitos adversos na pele da face associados ao uso da VNI.

ELMO, a new helmet interface for CPAP to treat COVID-19-related acute hypoxemic respiratory failure outside the ICU: a feasibility study / ELMO, uma nova interface do tipo capacete para CPAP no tratamento da insuficiência respiratória aguda hipoxêmica por COVID-19 fora da UTI: estudo de viabilidade

ABSTRACT Objective: To assess the feasibility of using a new helmet interface for CPAP, designated ELMO, to treat COVID-19-related acute hypoxemic respiratory failure (AHRF) outside the ICU. Methods: This was a proof-of-concept study involving patients with moderate to severe AHRF secondary to COVID-19 admitted to the general ward of a public hospital. The intervention consisted of applying CPAP via the ELMO interface integrated with oxygen and compressed air flow meters (30 L/min each) and a PEEP valve (CPAP levels = 8-10 cmH2O), forming the ELMOcpap system. The patients were monitored for cardiorespiratory parameters, adverse events, and comfort. Results: Ten patients completed the study protocol. The ELMOcpap system was well tolerated, with no relevant adverse effects. Its use was feasible outside the ICU for a prolonged amount of time and was shown to be successful in 60% of the patients. A CPAP of 10 cmH2O with a total gas flow of 56-60 L/min improved oxygenation after 30-to 60-min ELMOcpap sessions, allowing a significant decrease in estimated FIO2 (p = 0.014) and an increase in estimated PaO2/FIO2 ratio (p = 0.008) within the first hour without CO2 rebreathing. Conclusions: The use of ELMOcpap has proven to be feasible and effective in delivering high-flow CPAP to patients with COVID-19-related AHRF outside the ICU. There were no major adverse effects, and ELMO was considered comfortable. ELMOcpap sessions significantly improved oxygenation, reducing FIO2 without CO2 rebreathing. The overall success rate was 60% in this pilot study, and further clinical trials should be carried out in the future. (ClinicalTrials.gov identifier: NCT04470258 [http://www.clinicaltrials.gov/])

RESUMO Objetivo: Avaliar a viabilidade do uso de uma nova interface do tipo capacete para CPAP, denominada ELMO, para o tratamento da insuficiência respiratória aguda (IRpA) hipoxêmica por COVID-19 fora da UTI. Métodos: Estudo de prova de conceito envolvendo pacientes com IRpA hipoxêmica moderada a grave secundária à COVID-19, internados na enfermaria geral de um hospital público. A intervenção consistiu na aplicação de CPAP por meio da interface ELMO integrada a fluxômetros de oxigênio e ar comprimido (30 L/min cada) e a uma válvula de PEEP (níveis de CPAP = 8-10 cmH2O), formando o sistema ELMOcpap. Os pacientes foram monitorados quanto a parâmetros cardiorrespiratórios, eventos adversos e conforto. Resultados: Dez pacientes completaram o protocolo do estudo. O sistema ELMOcpap foi bem tolerado, sem efeitos adversos relevantes. Seu uso foi viável fora da UTI por tempo prolongado e mostrou-se bem-sucedido em 60% dos pacientes. Uma CPAP de 10 cmH2O com fluxo total de gás de 56-60 L/min melhorou a oxigenação após sessões de ELMOcpap de 30-60 min, permitindo redução significativa da FIO2 estimada (p = 0,014) e aumento da PaO2/FIO2 estimada (p = 0,008) na primeira hora, sem reinalação de CO2. Conclusões: O uso do ELMOcpap mostrou-se viável e eficaz no fornecimento de CPAP de alto fluxo a pacientes com IRpA hipoxêmica por COVID-19 fora da UTI. Não houve nenhum efeito adverso importante, e o ELMO foi considerado confortável. As sessões de ELMOcpap melhoraram significativamente a oxigenação, reduzindo a FIO2 sem reinalação de CO2. A taxa global de sucesso foi de 60% neste estudo piloto, e novos ensaios clínicos devem ser realizados. (ClinicalTrials.gov identifier: NCT04470258 [http://www.clinicaltrials.gov/])

A Critical Review of Mechanical Ventilation Virtual Simulators: Is It Time to Use Them?

BACKGROUND: Teaching mechanical ventilation at the bedside with real patients is difficult with many logistic limitations. Mechanical ventilators virtual simulators (MVVS) may have the potential to facilitate mechanical ventilation (MV) training by allowing Web-based virtual simulation. OBJECTIVE: We aimed to identify and describe the current available MVVS, to compare the usability of their interfaces as a teaching tool and to review the literature on validation studies. METHODS: We performed a comparative evaluation of the MVVS, based on a literature/Web review followed by usability tests according to heuristic principles evaluation of their interfaces as performed by professional experts on MV. RESULTS: Eight MVVS were identified. They showed marked heterogeneity, mainly regarding virtual patient's anthropomorphic parameters, pulmonary gas exchange, respiratory mechanics and muscle effort configurations, ventilator terminology, basic ventilatory modes, settings alarms, monitoring parameters, and design. The Hamilton G5 and the Xlung covered a broader number of parameters, tools, and have easier Web-based access. Except for the Xlung, none of the simulators displayed monitoring of arterial blood gases and alternatives to load and save the simulation. The Xlung obtained the greater scores on heuristic principles assessments and the greater score of easiness of use, being the preferred MVVS for teaching purposes. No strong scientific evidence on the use and validation of the current MVVS was found. CONCLUSIONS: There are only a few MVVS currently available. Among them, the Xlung showed a better usability interface. Validation tests and development of new or improvement of the current MVVS are needed.

Protective mechanical ventilation in patients with risk factors for ARDS: prospective cohort study / Ventilação mecânica protetora em pacientes com fator de risco para SDRA: estudo de coorte prospectiva

ABSTRACT Objective: To evaluate the association that protective mechanical ventilation (MV), based on VT and maximum distending pressure (MDP), has with mortality in patients at risk for ARDS. Methods: This was a prospective cohort study conducted in an ICU and including 116 patients on MV who had at least one risk factor for the development of ARDS. Ventilatory parameters were collected twice a day for seven days, and patients were divided into two groups (protective MV and nonprotective MV) based on the MDP (difference between maximum airway pressure and PEEP) or VT. The outcome measures were 28-day mortality, ICU mortality, and in-hospital mortality. The risk factors associated with the adoption of nonprotective MV were also assessed. Results: Nonprotective MV based on VT and MDP was applied in 49 (42.2%) and 38 (32.8%) of the patients, respectively. Multivariate Cox regression showed that protective MV based on MDP was associated with lower in-hospital mortality (hazard ratio = 0.37; 95% CI: 0.19-0.73) and lower ICU mortality (hazard ratio = 0.40; 95% CI: 0.19-0.85), after adjustment for age, Simplified Acute Physiology Score 3, and vasopressor use, as well as the baseline values for PaO2/FiO2 ratio, PEEP, pH, and PaCO2. These associations were not observed when nonprotective MV was based on the VT. Conclusions: The MDP seems to be a useful tool, better than VT, for adjusting MV in patients at risk for ARDS.

RESUMO Objetivo: Avaliar a associação da ventilação mecânica (VM) protetora, com base no VT e na pressão de distensão máxima (PDM), com a mortalidade em pacientes com fator de risco para SDRA. Métodos: Este estudo de coorte prospectivo foi conduzido em uma UTI e incluiu 116 pacientes em VM que apresentavam pelo menos um fator de risco para o desenvolvimento de SDRA. Os parâmetros ventilatórios foram coletados duas vezes ao dia durante sete dias, e os pacientes foram divididos em dois grupos (VM protetora e VM não protetora) com base na PDM (diferença entre pressão máxima de vias aéreas e PEEP) ou no VT. Os desfechos foram mortalidade em 28 dias, mortalidade na UTI e mortalidade hospitalar. Os fatores de risco associados com a adoção da VM não protetora também foram avaliados. Resultados: A VM não protetora com base no VT e na PDM ocorreu em 49 (42,2%) e em 38 (32,8%) dos pacientes, respectivamente. A regressão multivariada de Cox mostrou que a VM protetora com base na PDM associou-se a menor mortalidade hospitalar (hazard ratio = 0,37; IC95%: 0,19-0,73) e em UTI (hazard ratio = 0,40; IC95%, 0,19-0,85), após ajuste para idade, Simplified Acute Physiology Score 3, uso de vasopressor e valores basais de PaO2/FiO2, PEEP, pH e PaCO2. Essas associações não foram observadas quando a VM não protetora foi baseada no VT. Conclusões: A PDM parece ser uma ferramenta útil, melhor do que o VT, para o ajuste da VM em pacientes sob risco para SDRA.

Influência da ventilação assistida e dos ajustes do ventilador mecânico sobre o volume corrente e as pressões alveolares na síndrome do desconforto respiratório agudo: um estudo de bancada / Influences of assisted breathing and mechanical ventilator settings on tidal volume and alveolar pressures in acute respiratory distress syndrome: a bench study

RESUMO Objetivo: Avaliar a influência dos esforços musculares respiratórios e do ajuste da frequência respiratória no ventilador sobre o volume corrente e as pressões de distensão alveolar ao final da inspiração e expiração com ventilação sob os modos controle por volume e controle por pressão na síndrome do desconforto respiratório agudo. Métodos: Utilizou-se um simulador mecânico de pulmão (ASL 5000™) conectado a cinco tipos de ventiladores utilizados em unidade de terapia intensiva, em um modelo de síndrome do desconforto respiratório agudo. Os esforços musculares respiratórios (pressão muscular) foram configurados de três formas distintas: sem esforço (pressão muscular: 0cmH2O), apenas esforços inspiratórios (pressão muscular: - 5cmH2O, tempo inspiratório neural de 0,6 segundos) e esforços musculares inspiratórios e expiratórios (pressão muscular:-5/+5cmH2O). Foram configuradas ventilação sob os modos controle por volume e ventilação com controle por pressão para oferecer um volume corrente de 420mL e pressão positiva expiratória final de 10cmH2O. Avaliaram-se o volume corrente fornecido aos pulmões, as pressões alveolares no final da inspiração e as pressões alveolares no final da expiração. Resultados: Quando disparado pelo paciente simulado, o volume corrente mediano foi 27mL menor do que o volume corrente ajustado (variação-63 a +79mL), e ocorreu uma variação nas pressões alveolares com mediana de 25,4cmH2O (faixa de 20,5 a 30cmH2O). Nos cenários simulados com esforço muscular tanto inspiratório quanto expiratório e com frequência respiratória mandatória inferior à dos esforços do paciente simulado, o volume corrente mediano foi maior com ventilação controlada. Conclusão: O ajuste do esforço muscular respiratório e da frequência respiratória no ventilador em um valor acima da frequência respiratória do paciente nos modos de ventilação assistida/controlada gerou maiores variações no volume corrente e nas pressões pulmonares, enquanto o modo controlado não mostrou variações nesses desfechos.

ABSTRACT Objective: To evaluate the influences of respiratory muscle efforts and respiratory rate setting in the ventilator on tidal volume and alveolar distending pressures at end inspiration and expiration in volume-controlled ventilation and pressure-controlled ventilation modes in acute respiratory distress syndrome. Methods: An active test lung (ASL 5000™) connected to five intensive care unit ventilators was used in a model of acute respiratory distress syndrome. Respiratory muscle efforts (muscle pressure) were configured in three different ways: no effort (muscle pressure: 0cmH2O); inspiratory efforts only (muscle pressure:-5cmH2O, neural inspiratory time of 0.6s); and both inspiratory and expiratory muscle efforts (muscle pressure:-5/+5cmH2O). Volume-controlled and pressure-controlled ventilation modes were set to deliver a target tidal volume of 420mL and positive end-expiratory pressure of 10cmH2O. The tidal volume delivered to the lungs, alveolar pressures at the end of inspiration, and alveolar pressures at end expiration were evaluated. Results: When triggered by the simulated patient, the median tidal volume was 27mL lower than the set tidal volume (range-63 to +79mL), and there was variation in alveolar pressures with a median of 25.4cmH2O (range 20.5 to 30cmH2O). In the simulated scenarios with both spontaneous inspiratory and expiratory muscle efforts and with a mandatory respiratory rate lower than the simulated patient's efforts, the median tidal volume was higher than controlled breathing. Conclusion: Adjusting respiratory muscle effort and pulmonary ventilator respiratory rate to a value above the patient's respiratory rate in assisted/controlled modes generated large variations in tidal volume and pulmonary pressures, while the controlled mode showed no variations in these outcomes.