Cardiopulmonary effects of prolonged surgical abdominal retractors application during general anesthesia: a prospective observational comparative study

Abstract Introduction: Increasing abdominal pressures could affect pulmonary compliance and cardiac performance, a fact based on which the aim of the present study to detect the cardiopulmonary burden of multiple retractors application during supine versus lateral abdominal surgeries. We hypothesized that surgical ring multiple retractors application would affect the pulmonary and cardiac functions during both lateral and supine abdominal surgeries. Methods: Prospective observational comparative study on forty surgical patients subdivided into two groups twenty each, comparing pulmonary compliance and cardiac performance before, during and after retractors application, group (S) supine position cystectomy surgery, and group (L) lateral position nephrectomy surgery under general anesthesia, Composite 1ry outcome; dynamic compliance C-dyn and cardiac index CI and Other outcome variables ICON cardio-meter were also recorded. Results: C-dyn and C-stat were significantly decreased late during retractor application in lateral compared to supine surgery with significant decrease compared to basal values all over the surgical time. CI was significantly increased after retractor removal in both of the study groups compared to basal values. PAW P was significantly increased in -lateral compared to supine surgery -with significant increase compared to basal value all over the surgical time in both of the study groups. significant increase in DO2I compared to basal value during both supine and lateral positions. Conclusion: Surgical retraction results in a short-lived significant decreases in lung compliance and cardiac output particularly during the lateral-kidney position than the supine position compliance.

Fisiología respiratoria: fisiología de las enfermedades pulmonares restrictivas / Pathophysiology of pulmonary restrictive diseases

Las enfermedades restrictivas comprenden un grupo heterogéneo de trastornos que se caracterizan por una alteración en la distensibilidad pulmonar, generada por enfermedades del parénquima o intersticio pulmonar o por problemas extrapulmonares (alteraciones de la caja torácica o enfermedades neuromusculares). Presentan un patrón característico en las pruebas de función pulmonar, relación VEF1/ FVC normal o aumentada con CVF disminuida, VEF1 disminuido leve o normal y capacidad pulmonar total disminuida (CPT). Su manejo es complejo debido a la dificultad para establecer el diagnóstico diferencial, por lo que se recomienda una derivación precoz a un especialista en enfermedades respiratorias y el enfrentamiento por un equipo multidisciplinario.

Restrictive diseases comprise a heterogeneous group of disorders characterized by an alteration in lung compliance, generated by diseases of the lung parenchyma or interstitium, as well as by extrapulmonary problems (abnormalities of the rib cage or neuromuscular diseases). They present a characteristic pattern in pulmonary function tests, with decreased FVC (forced vital capacity), slightly decreased or normal FEV1 (forced expiratory volume in 1 second), normal or increased FEV1/FVC ratio, and decreased total lung capacity. Its management is complex due to the difficulty in establishing the differential diagnosis, so early referral to a specialist in respiratory diseases and confrontation by a multidisciplinary team is recommended.

Association between lung compliance phenotypes and mortality in COVID-19 patients with acute respiratory distress syndrome

INTRODUCTION@#Acute respiratory distress syndrome (ARDS) in COVID-19 is associated with a high mortality rate, though outcomes of the different lung compliance phenotypes are unclear. We aimed to measure lung compliance and examine other factors associated with mortality in COVID-19 patients with ARDS.@*METHODS@#Adult patients with COVID-19 ARDS who required invasive mechanical ventilation at 8 hospitals in Singapore were prospectively enrolled. Factors associated with both mortality and differences between high (<40mL/cm H@*RESULTS@#A total of 102 patients with COVID-19 who required invasive mechanical ventilation were analysed; 15 (14.7%) did not survive. Non-survivors were older (median 70 years, interquartile range [IQR] 67-75 versus median 61 years, IQR 52-66; @*CONCLUSION@#COVID-19 ARDS patients with higher compliance on the day of intubation and a longitudinal decrease over time had a higher risk of death.

Reprodutibilidade das mensurações da mecânica respiratória em pacientes sob ventilação mecânica invasiva / Reproducibility of respiratory mechanics measurements in patients on invasive mechanical ventilation

RESUMO Objetivo: Avaliar a reprodutibilidade intra e interexaminador das mensurações da resistência e das complacências estática e dinâmica do sistema respiratório em pacientes sob ventilação mecânica. Métodos: Trata-se de estudo analítico realizado com indivíduos com idade ≥ 18 anos, em ventilação mecânica invasiva, que não tinham diagnóstico clínico de doença do aparelho respiratório e/ou anormalidade de caixa torácica. Foram realizadas três aferições da mecânica respiratória com intervalo de 1 minuto entre elas. A primeira e a terceira aferições foram realizadas pelo avaliador A e a segunda aferição, pelo avaliador B. A comparação dos valores de resistência e complacências estática e dinâmica do sistema respiratório foi calculada por meio do coeficiente de correlação intraclasse. Resultados: Foram realizadas 198 aferições da mecânica respiratória em 66 pacientes sob ventilação mecânica, com idade média de 52,6 ± 18,6 anos, índice de massa corporal médio de 21,6 ± 2,1kg/m2, predomínio do perfil cirúrgico (61,5%) e sexo feminino (53,8%). Foram obtidos valores médios das três aferições para resistência do sistema respiratório (A1: 15,7 ± 6,8cmH2O/L/s; B1: 15,7 ± 6,4cmH2O/L/s e A2: 15,9 ± 6,2cmH2O/L/s), para complacência estática do sistema respiratório (A1: 42,1 ± 13,7mL/cmH2O; B1: 42,4 ± 14,6mL/cmH2O e A2: 42,2 ± 14,5mL/cmH2O) e para complacência dinâmica do sistema respiratório (A1: 21,3 ± 7,3mL/cmH2O; B1: 21,4 ± 7,5mL/cmH2O e A2: 21,3 ± 6,2mL/cmH2O). Também foram encontrados valores do coeficiente de correlação intraclasse para resistência do sistema respiratório (R = 0,882 e p = 0,001; R = 0,949 e p = 0,001 - interexaminadores A1 versus B e B versus A2, respectivamente; R = 0,932 e p = 0,001 - intraexaminador); complacência estática do sistema respiratório (R = 0,951 e p = 0,001; R = 0,958 e p = 0,001 - interexaminadores A1 versus B e B versus A2, respectivamente; R = 0,965 e p = 0,001 - intraexaminador) e complacência dinâmica do sistema respiratório (R = 0,957 e p = 0,001; R = 0,946 e p = 0,001 - interexaminadores A1 versus B e B versus A2 respectivamente; R = 0,926 e p = 0,001 - intraexaminador). Conclusão: A mensuração de mecânica respiratória apresenta boa reprodutibilidade intra e interexaminador para as aferições de resistência e complacências estática e dinâmica do sistema respiratório em pacientes ventilados.

ABSTRACT Objective: To evaluate the intra- and interexaminer reproducibility of measurements of the resistance and static and dynamic compliance of the respiratory system in patients on mechanical ventilation. Methods: This was an analytical study conducted with individuals aged ≥ 18 years who were on invasive mechanical ventilation and had no clinical diagnosis of respiratory system disease and/or chest abnormality. Three measurements of respiratory mechanics were performed with a 1-minute interval between them. The first and third measurements were performed by examiner A, the second by examiner B. The values for the resistance and static and dynamic compliance of the respiratory system were compared using the intraclass correlation coefficient. Results: A total of 198 measurements of respiratory mechanics were performed for 66 patients on mechanical ventilation. The patients had a mean age of 52.6 ± 18.6 years and a mean body mass index of 21.6 ± 2.1kg/m2; a surgical profile (61.5%) and female sex (53.8%) were predominant. Mean values were obtained for the three measurements of respiratory system resistance (A1: 15.7 ± 6.8cmH2O/L/s; B1: 15.7 ± 6.4cmH2O/L/s and A2: 15.9 ± 6.2cmH2O/L/s), respiratory system static compliance (A1: 42.1 ± 13.7mL/cmH2O; B1: 42.4 ± 14.6mL/cmH2O and A2: 42.2 ± 14.5mL/cmH2O) and respiratory system dynamic compliance (A1: 21.3 ± 7.3mL/cmH2O; B1: 21.4 ± 7.5mL/cmH2O and A2: 21.3 ± 6.2mL/cmH2O). The intraclass correlation coefficient was also calculated for respiratory system resistance (R = 0.882 and p = 0.001; R = 0.949 and p = 0.001 - interexaminer A1 versus B and B versus A2, respectively; R = 0.932 and p = 0.001 - intraexaminer); respiratory system static compliance (R = 0.951 and p = 0.001; R = 0.958 and p = 0.001 - interexaminer A1 versus B and B versus A2, respectively; R = 0.965 and p = 0.001 - intraexaminer) and respiratory system dynamic compliance (R = 0.957 and p = 0.001; R = 0.946 and p = 0.001 - interexaminer A1 versus B and B versus A2, respectively; R = 0.926 and p = 0.001 - intraexaminer). Conclusion: The measurements of resistance and static and dynamic compliance of the respiratory system show good intra- and interexaminer reproducibility for ventilated patients.

Comparison of pressure-controlled volume-guaranteed ventilation and volume-controlled ventilation in obese patients during gynecologic laparoscopic surgery in the Trendelenburg position / Comparação entre ventilação garantida por volume controlado por pressão e ventilação controlada por volume em pacientes obesos durante cirurgia laparoscópica ginecológica na posição de Trendelenburg

Abstract Background and objectives: The aim of this study was to investigate the efficacy of the pressure-controlled, volume-guaranteed (PCV-VG) and volume-controlled ventilation (VCV) modes for maintaining adequate airway pressures, lung compliance and oxygenation in obese patients undergoing laparoscopic hysterectomy in the Trendelenburg position. Methods: Patients (104) who underwent laparoscopic gynecologic surgery with a body mass index between 30 and 40 kg.m-2 were randomized to receive either VCV or PCV-VG ventilation. The tidal volume was set at 8 mL.kg-1, with an inspired oxygen concentration of 0.4 with a Positive End-Expiratory Pressure (PEEP) of 5 mmHg. The peak inspiratory pressure, mean inspiratory pressure, plateau pressure, driving pressure, dynamic compliance, respiratory rate, exhaled tidal volume, etCO2, arterial blood gas analysis, heart rate and mean arterial pressure at 5 minutes after induction of anesthesia in the and at 5, 30 and 60 minutes, respectively, after pneumoperitoneum in the Trendelenburg position were recorded. Results: The PCV-VG group had significantly decreased peak inspiratory pressure, mean inspiratory pressur, plateau pressure, driving pressure and increased dynamic compliance compared to the VCV group. Mean PaO2 levels were significantly higher in the PCV-VG group than in the VCV group at every time point after pneumoperitoneum in the Trendelenburg position. Conclusions: The PCV-VG mode of ventilation limited the peak inspiratory pressure, decreased the driving pressure and increased the dynamic compliance compared to VCV in obese patients undergoing laparoscopic hysterectomy. PCV-VG may be a preferable modality to prevent barotrauma during laparoscopic surgeries in obese patients.

Resumo Justificativa e objetivos: O objetivo deste estudo foi investigar a eficácia dos modos de ventilação garantida por volume controlado por pressão (PCV-VG) e ventilação controlada por volume (VCV) para manter pressões adequadas nas vias aéreas, complacência pulmonar e oxigenação em pacientes obesos submetidos à histerectomia laparoscópica na posição de Trendelenburg. Métodos: Cento e quatro pacientes submetidos à cirurgia ginecológica laparoscópica, com índice de massa corporal entre 30 e 40 kg.m-2, foram randomizados para receber ventilação com VCV ou PCV-VG. O volume corrente foi fixado em 8 mL.kg-1, com uma concentração inspirada de oxigênio de 0,4 e pressão positiva expiratória final (PEEP) de 5 mmHg. Registramos os seguintes parâmetros: pressão de pico inspiratório, pressão inspiratória média, pressão de platô, driving pressure, complacência dinâmica, frequência respiratória, volume corrente expirado, etCO2, gasometria arterial, frequência cardíaca e pressão arterial média aos 5, 30 e 60 minutos, respectivamente, após o pneumoperitônio na posição de Trendelenburg. Resultados: O grupo PCV-VG apresentou uma redução significativa da pressão de pico inspiratório, pressão inspiratória média, pressão de platô, driving pressure e aumento da complacência dinâmica comparado ao grupo VCV. Os níveis médios de PaO2 foram significativamente maiores no grupo PCV-VG do que no grupo VCV em todos os momentos após o pneumoperitônio na posição de Trendelenburg. Conclusões: O modo de ventilação PCV-VG limitou a pressão de pico inspiratório, diminuiu a driving pressure e aumentou a complacência dinâmica, comparado ao VCV em pacientes obesas submetidas à histerectomia laparoscópica. O PCV-VG pode ser uma modalidade preferida para prevenir o barotrauma durante cirurgias laparoscópicas em pacientes obesos.

Insuflador-exsuflador mecânico versus manobra PEEP-ZEEP em pacientes em ventilação mecânica prolongada / Mechanical insufflator-exsufflator versus PEEP-ZEEP maneuver in patients on prolonged mechanical ventilation

Introdução: A presença da via aérea artificial, associada com a imobilidade no leito, resulta em um déficit na desobstrução das vias aéreas em pacientes sob ventilação mecânica (VM). Tal condição contribui para o desenvolvimento de quadros de hipoxemia e/ou infecções respiratórias, aumentando o trabalho respiratório e também as falhas de extubação. Objetivo: Comparar os efeitos da utilização do insuflador-exsuflador mecânico e da manobra PEEP-ZEEP em relação à mecânica respiratória em pacientes ventilados mecanicamente por tempo prolongado. Métodos: Ensaio clínico randomizado cruzado, incluindo pacientes em ventilação mecânica por mais de 10 dias. Os pacientes foram randomizados para receber a aplicação do insuflador-exsuflador mecânico e da manobra PEEP-ZEEP. Foram mensuradas complacência pulmonar, estática e dinâmica, e resistência pulmonar antes e após a aplicação de cada técnica. Resultados: Foram incluídos 22 pacientes. Na análise intragrupos observa-se aumento significativo na complacência dinâmica e complacência estática após a aplicação de ambas as técnicas. A resistência pulmonar variou significativamente apenas após a aplicação do insuflador-exsuflador mecânico. Não foram observadas diferenças significativas na análise intergrupos. Conclusão: O insuflador-exsuflador mecânico e a manobra de PEEP-ZEEP demonstraram ter efeito positivo tanto sobre a complacência estática quanto a dinâmica. Entretanto, a resistência pulmonar aumentou após a aplicação do insuflador-exsuflador mecânico. (AU)

Introduction: The presence of the artificial airway associated with immobility in the bed results in a deficit in the clearance of the airways in patients under mechanical ventilation (MV). This condition contributes to the development of hypoxemia and/or respiratory infections, increasing respiratory work and also extubation failures. Objective: To compare the effects of the use of mechanical insufflation-exsufflation and PEEP-ZEEP maneuver in relation to respiratory mechanics in patients on prolonged mechanical ventilation. Methods: Randomized cross-over trial, including patients on mechanical ventilation for more than 10 days. The patients were randomized to receive the application of mechanical insufflator-exsuflator and PEEP-ZEEP maneuver. Pulmonary compliance, static and dynamic, and pulmonary resistance were measured before and after the application of each technique. Results: 22 patients were included. In the intragroup analysis we observed a significant increase in the dynamic compliance and static compliance after the application of both techniques. Pulmonary resistance varied significantly only after application of the mechanical insufflation-exsufflation. No significant differences were observed in the inter-group analysis. Conclusion: The mechanical insufflator-exsuflator and the PEEP-ZEEP maneuver were shown to have a positive effect on both static and dynamic complacency. However, pulmonary resistance increased after the application of the mechanical insufflation-exsufflation.(AU)

The Effects of Chest Physiotherapy on Applied to Patients Mechanicalventilated: In Patients with Acute Lung Injury / 중환자간호학회지

PURPOSE: The purpose of this study was to examine the effects of two single chest physiotherapies mechanically ventilated patients with acute lung injury.METHOD: Participants were 30 ICU patients depending entirely on ventilators without self-respiration. Each patients received two single chest physiotherapiesvibration palm cup percussion at hour intervals. Data were analyzed one-way ANOVA and Wilcoxon signed-rank test. Statistical significance was accepted at a p value less than .05.RESULTS: ibration therapy, dynamic compliance and statics compliance demonstrated a significant increase immediately and remained increased until 30 minutes after chest physiotherapy. palm cum percussion therapy saturation showed a significant increase immediately chest physiotherapyut there were no significant differences in tidal volume, dynamic compliance and statics compliance.CONCLUSION: In this study, we analyzed the effects of oscillation method and palm cup percussion method separately for each type of chest physiotherapy. Nursing interventions that actively utilize vibration methods should be provided to patients with respiratory diseases.

Comparison of clinical performance of i-gelⓇ and Baska MaskⓇ during laparoscopic cholecystectomy / 대한마취과학회지

BACKGROUND: The supraglottic airway device is an appropriate alternative to tracheal intubation in laparoscopic surgery. We compared the Baska MaskⓇ with i-gelⓇ by measuring the oropharyngeal leak pressure (OLP) and hemodynamic and respiratory parameters during laparoscopic cholecystectomy.METHODS: A total of 97 patients were randomly allocated to either i-gel group (n = 49) or Baska Mask group (n = 48). Insertion time, number of insertion attempts, fiber-optic view of the glottis, and OLP were recorded. Heart rate, mean arterial pressure, peak airway pressure (PAP), lung compliance, and perioperative complications were assessed before, during, and after pneumoperitoneum.RESULTS: There were no significant differences between the two groups regarding demographic data, insertion time, fiber-optic view of the glottis, and the use of airway manipulation. The OLP was higher in the Baska Mask group than in the i-gel group (29.6 ± 6.8 cmH₂O and 26.7 ± 4.5 cmH₂O, respectively; P = 0.014). Heart rate, mean arterial pressure, PAP, and lung compliance were not significantly different between the groups. The incidence of perioperative complications was small and not statistically significant.CONCLUSIONS: Both the i-gel and Baska Mask provided a satisfactory airway during laparoscopic cholecystectomy. Compared with the i-gel, the Baska Mask demonstrated a higher OLP.

Effects of propofol, desflurane, and sevoflurane on respiratory functions following endoscopic endonasal transsphenoidal pituitary surgery: a prospective randomized study / 대한마취과학회지

BACKGROUND: General anesthesia with intravenous or inhalation anesthetics reduces respiratory functions. We investigated the effects of propofol, desflurane, and sevoflurane on postoperative respiratory function tests.METHODS: This single-center randomized controlled study was performed in a university hospital from October 2015 to February 2017. Ninety patients scheduled for endoscopic endonasal transsphenoidal pituitary surgery were randomly categorized into either of these three groups: propofol (n = 30, the Group TIVA), desflurane (n = 30, the Group D) or sevoflurane (n = 30, the Group S). We analyzed the patients before, after, and 24 h following surgery, to identify the following parameters: forced expiratory volume in 1 second (FEV₁) %, forced vital capacity (FVC) %, FEV₁/FVC, and arterial blood gases (ABG). Furthermore, we also recorded the intraoperative dynamic lung compliance and airway resistance values.RESULTS: We did not find any significant differences in FEV₁ values (primary outcome) among the groups (P = 0.336). There was a remarkable reduction in the FEV₁ and FVC values in all groups postoperatively relative to the baseline (P < 0.001). The FVC, FEV₁/FVC, ABG analysis, compliance, and airway resistance were similar among the groups. Intraoperative dynamic compliance values were lower at the 1st and 2nd hours than those immediately after intubation (P < 0.001).CONCLUSIONS: We demonstrated that propofol, desflurane, and sevoflurane reduced FEV₁ and FVC values postoperatively, without any significant differences among the drugs.

Evaluation and reconditioning of donor organs for transplantation through ex vivo lung perfusion / Avaliação e recondicionamento de pulmões doados para transplante por meio da perfusão pulmonar ex vivo

ABSTRACT Objective: To assess the feasibility and impact of ex vivo lung perfusion with hyperoncotic solution (Steen Solution™) in the utilization of these organs in Brazil. Methods: In this prospective study, we subjected five lungs considered to be high risk for transplantation to 4 hours of ex vivo lung perfusion, with evaluation of oxygenation capacity. High-risk donor lungs were defined by specific criteria, including inflammatory infiltrates, pulmonary edema and partial pressure of arterial oxygen less than 300mmHg (inspired oxygen fraction of 100%). Results: During reperfusion, the mean partial pressure of arterial oxygen (inspired oxygen fraction of 100%) of the lungs did not change significantly (p=0.315). In the first hour, the mean partial pressure of arterial oxygen was 302.7mmHg (±127.66mmHg); in the second hour, 214.2mmHg (±94.12mmHg); in the third hour, 214.4mmHg (±99.70mmHg); and in the fourth hour, 217.7mmHg (±73.93mmHg). Plasma levels of lactate and glucose remained stable during perfusion, with no statistical difference between the moments studied (p=0.216). Conclusion: Ex vivo lung perfusion was reproduced in our center and ensured the preservation of lungs during the study period, which was 4 hours. The technique did not provide enough improvement for indicating organs for transplantation; therefore, it did not impact on use of these organs.

RESUMO Objetivo: Avaliar a exequibilidade e o impacto da perfusão pulmonar ex vivo com solução hiperoncótica (Steen Solution™) na taxa de utilização desses órgãos no Brasil. Métodos: Neste estudo prospectivo, submetemos cinco pulmões considerados de alto risco para o transplante a 4 horas de perfusão pulmonar ex vivo, com avaliação da capacidade de oxigenação pulmonar. Os pulmões de doadores de alto risco foram definidos por critérios específicos, incluindo infiltrado inflamatório, edema pulmonar e pressão parcial de oxigênio arterial inferior a 300mmHg (fração inspirada de oxigênio de 100%). Resultados: Durante a reperfusão, a pressão parcial de oxigênio arterial (fração inspirada de oxigênio de 100%) média dos pulmões não sofreu alteração significativa (p=0,315). Na primeira hora, a pressão parcial de oxigênio arterial média foi de 302,7mmHg (±127,66mmHg); na segunda, 214,2mmHg (±94,12mmHg); na terceira, 214,4mmHg (±99,70mmHg); e na quarta, 217,7mmHg (±73,93mmHg). Os níveis plasmáticos de lactato e glicose se mantiveram estáveis ao longo da perfusão, sem diferença estatística na comparação entre os momentos estudados (p=0,216). Conclusão: A perfusão pulmonar ex vivo foi reproduzida em nosso centro e garantiu a preservação de pulmões durante o período de estudo, que foi de 4 horas. A técnica não promoveu melhora suficiente para indicação do órgão para o transplante e, portanto, não impactou na taxa de utilização desses órgãos.

The effect of tulobuterol patches on the respiratory system after endotracheal intubation

BACKGROUND: Endotracheal intubation during anesthesia induction may increase airway resistance (R(aw)) and decrease dynamic lung compliance (Cdyn). We hypothesized that prophylactic treatment with a transdermal β2-agonist tulobuterol patch (TP) would help to reduce the risk of bronchospasm after placement of the endotracheal tube. METHODS: Eighty-two American Society of Anesthesiologists (ASA) category I or II adult patients showing obstructive patterns were divided randomly into a control and a TP group (n = 41 each). The night before surgery, a 2-mg TP was applied to patients in the TP group. Standard monitors were recorded, and target controlled infusion (TCI) with propofol and remifentanil was used for anesthesia induction and maintenance. Simultaneously, end-tidal carbon dioxide, R(aw), and Cdyn were determined at 5, 10, and 15 min intervals after endotracheal intubation. RESULTS: There was no significant difference in demographic data between the two groups. The TP group was associated with a lower R(aw) and a higher Cdyn, as compared to the control group. R(aw) was significantly lower at 10 min (P < 0.05) and 15 min (P < 0.01), and Cdyn was significantly higher at 5 min (P < 0.05) and 15 min (P < 0.01) in the TP group. A trend towards a lower R(aw) was observed showing a statistically significant difference 5 min after endotracheal intubation (P < 0.01) in each group. CONCLUSIONS: Prophylactic treatment with TP showed a bronchodilatory effect through suppressing an increase in R(aw) and a decrease in C(dyn) after anesthesia induction without severe adverse effects.

Evaluation of Respiratory Dynamics in an Asymmetric Lung Compliance Model / 대한구급학회지

BACKGROUND: Unilateral lung hyperinflation develops in lungs with asymmetric compliance, which can lead to vital instability. The aim of this study was to investigate the respiratory dynamics and the effect of airway diameter on the distribution of tidal volume during mechanical ventilation in a lung model with asymmetric compliance. METHODS: Three groups of lung models were designed to simulate lungs with a symmetric and asymmetric compliance. The lung model was composed of two test lungs, lung1 and lung2. The static compliance of lung1 in C15, C60, and C120 groups was manipulated to be 15, 60, and 120 ml/cmH₂O, respectively. Meanwhile, the static compliance of lung2 was fixed at 60 ml/cmH₂O. Respiratory variables were measured above (proximal measurement) and below (distal measurement) the model trachea. The lung model was mechanically ventilated, and the airway internal diameter (ID) was changed from 3 to 8 mm in 1-mm increments. RESULTS: The mean ± standard deviation ratio of volumes distributed to each lung (VL1/VL2) in airway ID 3, 4, 5, 6, 7, and 8 were in order, 0.10 ± 0.05, 0.11 ± 0.03, 0.12 ± 0.02, 0.12 ± 0.02, 0.12 ± 0.02, and 0.12 ± 0.02 in the C15 group; 1.05 ± 0.16, 1.01 ± 0.09, 1.00 ± 0.07, 0.97 ± 0.09, 0.96 ± 0.06, and 0.97 ± 0.08 in the C60 group; and 1.46 ± 0.18, 3.06 ± 0.41, 3.72 ± 0.37, 3.78 ± 0.47, 3.77 ± 0.45, and 3.78 ± 0.60 in the C120 group. The positive end-expiratory pressure (PEEP) of lung1 was significantly increased at airway ID 3 mm (1.65 cmH₂O) in the C15 group; at ID 3, 4, and 5 mm (2.21, 1.06, and 0.95 cmH₂O) in the C60 group; and ID 3, 4, and 5 mm (2.92, 1.84, and 1.41 cmH₂O) in the C120 group, compared to ID 8 mm (P < 0.05). CONCLUSIONS: In the C15 and C120 groups, the tidal volume was unevenly distributed to both lungs in a positive relationship with lung compliance. In the C120 group, the uneven distribution of tidal volume was improved when the airway ID was equal to or less than 4 mm, but a significant increase of PEEP was observed.

Is It Essential to Consider Respiratory Dynamics? / 대한구급학회지

No abstract available.

Evaluation of Respiratory Dynamics in an Asymmetric Lung Compliance Model / 대한중환자의학회지

BACKGROUND: Unilateral lung hyperinflation develops in lungs with asymmetric compliance, which can lead to vital instability. The aim of this study was to investigate the respiratory dynamics and the effect of airway diameter on the distribution of tidal volume during mechanical ventilation in a lung model with asymmetric compliance. METHODS: Three groups of lung models were designed to simulate lungs with a symmetric and asymmetric compliance. The lung model was composed of two test lungs, lung1 and lung2. The static compliance of lung1 in C15, C60, and C120 groups was manipulated to be 15, 60, and 120 ml/cmH₂O, respectively. Meanwhile, the static compliance of lung2 was fixed at 60 ml/cmH₂O. Respiratory variables were measured above (proximal measurement) and below (distal measurement) the model trachea. The lung model was mechanically ventilated, and the airway internal diameter (ID) was changed from 3 to 8 mm in 1-mm increments. RESULTS: The mean ± standard deviation ratio of volumes distributed to each lung (VL1/VL2) in airway ID 3, 4, 5, 6, 7, and 8 were in order, 0.10 ± 0.05, 0.11 ± 0.03, 0.12 ± 0.02, 0.12 ± 0.02, 0.12 ± 0.02, and 0.12 ± 0.02 in the C15 group; 1.05 ± 0.16, 1.01 ± 0.09, 1.00 ± 0.07, 0.97 ± 0.09, 0.96 ± 0.06, and 0.97 ± 0.08 in the C60 group; and 1.46 ± 0.18, 3.06 ± 0.41, 3.72 ± 0.37, 3.78 ± 0.47, 3.77 ± 0.45, and 3.78 ± 0.60 in the C120 group. The positive end-expiratory pressure (PEEP) of lung1 was significantly increased at airway ID 3 mm (1.65 cmH₂O) in the C15 group; at ID 3, 4, and 5 mm (2.21, 1.06, and 0.95 cmH₂O) in the C60 group; and ID 3, 4, and 5 mm (2.92, 1.84, and 1.41 cmH₂O) in the C120 group, compared to ID 8 mm (P < 0.05). CONCLUSIONS: In the C15 and C120 groups, the tidal volume was unevenly distributed to both lungs in a positive relationship with lung compliance. In the C120 group, the uneven distribution of tidal volume was improved when the airway ID was equal to or less than 4 mm, but a significant increase of PEEP was observed.

Is It Essential to Consider Respiratory Dynamics? / 대한중환자의학회지

No abstract available.

Effect of recruitment maneuver on arterial oxygenation in patients undergoing robot-assisted laparoscopic prostatectomy with intraoperative 15 cmH₂O positive end expiratory pressure / 대한마취과학회지

BACKGROUND: This randomized, controlled study was designed to compare the effects of recruitment maneuvers (RMs) with a 15 cmH₂O positive end-expiratory pressure (PEEP) on the systemic oxygenation and lung compliance of patients with healthy lungs following robot-assisted laparoscopic prostatectomy (RALP). METHODS: Sixty patients undergoing a RALP with an intraoperative 15 cmH₂O PEEP were randomly allocated to an RM or a Control group. The patients in the RM group received a single RM through the application of a continuous positive airway pressure of 40 cmH₂O for 40 s 15 min after being placed in the Trendelenburg position. The arterial oxygen tension (PaO₂, primary endpoint) and the pulmonary dynamic and static compliances (secondary endpoints) were measured 10 min after the anesthetic induction (T1), 10 min after establishment of the pneumoperitoneum (T2), 10 min after establishment of the Trendelenburg position (T3), 10 min after the RM (T4), 60 min after the RM (T5), and 10 min after deflation of the pneumoperitoneum in the supine position (T6). RESULTS: The intergroup comparisons of the PaO₂ showed significantly higher values in the RM group than in the Control group at T4 and T5 (193 ± 35 mmHg vs. 219 ± 33 mmHg, P = 0.015, 188 ± 41 mmHg vs. 214 ± 42 mmHg, P = 0.005, respectively). However, the PaO₂ at T6 was similar in the two groups (211 ± 39 mmHg vs. 224 ± 41 mmHg, P = 0.442). Moreover, there were no statistical differences between the groups in the dynamic and static compliances of the lungs at any time point. CONCLUSIONS: The arterial oxygenation of the patients with a healthy lung function who had undergone a RALP with intraoperative 15 cmH₂O PEEP was improved by a single RM. However, this benefit did not last long, and it did not lead to an amelioration of the lung mechanics.

Physiological Correlation of Airway Pressure and Transpulmonary Pressure Stress Index on Respiratory Mechanics in Acute Respiratory Failure / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Stress index at post-recruitment maneuvers could be a method of positive end-expiratory pressure (PEEP) titration in acute respiratory distress syndrome (ARDS) patients. However, airway pressure (Paw) stress index may not reflect lung mechanics in the patients with high chest wall elastance. This study was to evaluate the Pawstress index on lung mechanics and the correlation between Pawstress index and transpulmonary pressure (PL) stress index in acute respiratory failure (ARF) patients.</p><p><b>METHODS</b>Twenty-four ARF patients with mechanical ventilation (MV) were consecutively recruited from July 2011 to April 2013 in Zhongda Hospital, Nanjing, China and Ospedale S. Giovanni Battista-Molinette Hospital, Turin, Italy. All patients underwent MV with volume control (tidal volume 6 ml/kg) for 20 min. PEEP was set according to the ARDSnet study protocol. The patients were divided into two groups according to the chest wall elastance/respiratory system elastance ratio. The high elastance group (H group, n = 14) had a ratio ≥30%, and the low elastance group (L group, n = 10) had a ratio <30%. Respiratory elastance, gas-exchange, Pawstress index, and PLstress index were measured. Student's t-test, regression analysis, and Bland-Altman analysis were used for statistical analysis.</p><p><b>RESULTS</b>Pneumonia was the major cause of respiratory failure (71.0%). Compared with the L group, PEEP was lower in the H group (5.7 ± 1.7 cmH2O vs. 9.0 ± 2.3 cmH2O, P < 0.01). Compared with the H group, lung elastance was higher (20.0 ± 7.8 cmH2O/L vs. 11.6 ± 3.6 cmH2O/L, P < 0.01), and stress was higher in the L group (7.0 ± 1.9 vs. 4.9 ± 1.9, P = 0.02). A linear relationship was observed between the Pawstress index and the PLstress index in H group (R2 = 0.56, P < 0.01) and L group (R2 = 0.85, P < 0.01).</p><p><b>CONCLUSION</b>In the ARF patients with MV, Pawstress index can substitute for PLto guide ventilator settings.</p><p><b>TRIAL REGISTRATION</b>ClinicalTrials.gov NCT02196870 (https://clinicaltrials.gov/ct2/show/NCT02196870).</p>

Decreased lung compliance increases preload dynamic tests in a pediatric acute lung injury model / Una compliance pulmonar disminuida incrementa los test dinámicos de precarga en un modelo pediátrico de lesión pulmonar aguda

Background: Preload dynamic tests, pulse pressure variation (PPV) and stroke volume variation (SVV) have emerged as powerful tools to predict response to fluid administration. The influence of factors other than preload in dynamic preload test is currently poorly understood in pediatrics. The aim of our study was to assess the effect of tidal volume (V T) on PPV and SVV in the context of normal and reduced lung compliance in a piglet model. Material and method: Twenty large-white piglets (5.2 ± 0.4 kg) were anesthetized, paralyzed and monitored with pulse contour analysis. PPV and SVV were recorded during mechanical ventilation with a V T of 6 and 12 mL/kg (low and high V T, respectively), both before and after tracheal instillation of polysorbate 20. Results: Before acute lung injury (ALI) induction, modifications of V T did not significantly change PPV and SVV readings. After ALI, PPV and SVV were significantly greater during ventilation with a high V T compared to a low V T (PPV increased from 8.9 ± 1.2 to 12.4 ± 1.1%, and SVV from 8.5 ± 1.0 to 12.7 ± 1.2%, both P < 0.01). Conclusions: This study found that a high V T and reduced lung compliance due to ALI increase preload dynamic tests, with a greater influence of the latter. In subjects with ALI, lung compliance should be considered when interpreting the preload dynamic tests.

Introducción: Test dinámicos de precarga, variación de presión de pulso (PPV) y variación de volumen sistólico (SVV) han emergido como herramientas poderosas para predecir respuesta a la administración de fluidos. Actualmente la influencia de factores distintos a la precarga en la determinación de los test dinámicos de precarga es pobremente conocida en pediatría. Nuestro objetivo fue medir el efecto del volumen tidal (V T) sobre PPV y SVV en un contexto de compliance pulmonar normal y disminuida en un modelo porcino. Material y método: Veinte cerditos Large-White anestesiados y paralizados (5,2 ± 0,4 kg). PPV y SVV fueron medidos por análisis de contorno de pulso durante ventilación con V T de 6 y 12 mL/kg (V T bajo y alto, respectivamente), ambos previo y posterior a lesión pulmonar aguda (ALI) químicamente inducida con instilación traqueal de polisorbato 20. Resultados: Previo a inducción de ALI, PPV y SVV no tuvieron cambios significativos al modificar el V T. Sin embargo, después de ALI, PPV y SVV fueron significativamente mayores durante ventilación con V T alto, respecto a V T bajo (PPV aumentó de 8,9 ± 1,2 a 12,4 ± 1,1%, y SVV de 8,5 ± 1,0 a 12,7 ± 1,2%, ambos P < 0,01). Conclusiones: Este estudio encontró que un V T alto y una compliance pulmonar disminuida debido a ALI incrementan los test dinámicos de precarga, con una mayor influencia de esta última. En sujetos con ALI la compliance pulmonar debiera ser considerada al interpretar los test dinámicos de precarga.

Correlations between forced oscillation technique parameters and pulmonary densitovolumetry values in patients with acromegaly

The aims of this study were to evaluate the forced oscillation technique (FOT) and pulmonary densitovolumetry in acromegalic patients and to examine the correlations between these findings. In this cross-sectional study, 29 non-smoking acromegalic patients and 17 paired controls were subjected to the FOT and quantification of lung volume using multidetector computed tomography (Q-MDCT). Compared with the controls, the acromegalic patients had a higher value for resonance frequency [15.3 (10.9-19.7) vs 11.4 (9.05-17.6) Hz, P=0.023] and a lower value for mean reactance [0.32 (0.21-0.64) vs 0.49 (0.34-0.96) cm H2O/L/s2, P=0.005]. In inspiratory Q-MDCT, the acromegalic patients had higher percentages of total lung volume (TLV) for nonaerated and poorly aerated areas [0.42% (0.30-0.51%) vs 0.25% (0.20-0.32%), P=0.039 and 3.25% (2.48-3.46%) vs 1.70% (1.45-2.15%), P=0.001, respectively]. Furthermore, the acromegalic patients had higher values for total lung mass in both inspiratory and expiratory Q-MDCT [821 (635-923) vs 696 (599-769) g, P=0.021 and 844 (650-945) vs 637 (536-736) g, P=0.009, respectively]. In inspiratory Q-MDCT, TLV showed significant correlations with all FOT parameters. The TLV of hyperaerated areas showed significant correlations with intercept resistance (rs=−0.602, P<0.001) and mean resistance (rs=−0.580, P<0.001). These data showed that acromegalic patients have increased amounts of lung tissue as well as nonaerated and poorly aerated areas. Functionally, there was a loss of homogeneity of the respiratory system. Moreover, there were correlations between the structural and functional findings of the respiratory system, consistent with the pathophysiology of the disease.

Lowering Pulmonary Wedge Pressure after Heart Transplant: Pulmonary Compliance and Resistance Effect / Redução da Pressão Capilar Pulmonar após Transplante Cardíaco: Complacência Pulmonar e Efeito Resistência

AbstractBackground:Right ventricular (RV) afterload is an important risk factor for post-heart transplantation (HTx) mortality, and it results from the interaction between pulmonary vascular resistance (PVR) and pulmonary compliance (CPA). Their product, the RC time, is believed to be constant. An exception is observed in pulmonary hypertension because of elevated left ventricular (LV) filling pressures.Objective:Using HTx as a model for chronic lowering of LV filling pressures, our aim was to assess the variations in RV afterload components after transplantation.Methods:We retrospectively studied 159 patients with right heart catheterization before and after HTx. The effect of Htx on hemodynamic variables was assessed.Results:Most of the patients were male (76%), and the mean age was 53 ± 12 years. HTx had a significant effect on the hemodynamics, with normalization of the LV and RV filling pressures and a significant increase in cardiac output and heart rate (HR). The PVR decreased by 56% and CPA increased by 86%. The RC time did not change significantly, instead of increasing secondary to pulmonary wedge pressure (PWP) normalization after HTx as expected. The expected increase in RC time with PWP lowering was offset by the increase in HR (because of autonomic denervation of the heart). This effect was independent from the decrease of PWP.Conclusion:The RC time remained unchanged after HTx, notwithstanding the fact that pulmonary capillary wedge pressure significantly decreased. An increased HR may have an important effect on RC time and RV afterload. Studying these interactions may be of value to the assessment of HTx candidates and explaining early RV failure after HTx.

ResumoFundamento:A pós-carga do ventrículo direito (VD) é um fator de risco importante para avaliar a mortalidade decorrente de transplante cardíaco (HTx) e resulta da interação entre a resistência vascular pulmonar (RVP) e a complacência pulmonar (CPA). Acredita-se que o produto da interação, o RC-time, seja constante. Entretanto, é exceção a hipertensão pulmonar devido às elevadas pressões de preenchimento do ventrículo esquerdo (VE).Objetivos:Ao utilizar o HTx como modelo para redução crônica das pressões de preenchimento do VE, nosso objetivo foi avaliar as variações nos componentes pós-carga do VD após o transplante.Métodos:Foram estudados, retrospectivamente, 159 pacientes com cateterismo cardíaco direito realizado antes e após o HTx. O impacto do HTx nas variáveis hemodinâmicas foi avaliado.Resultados:A maioria dos pacientes foi do sexo masculino (76%) e a média de idade foi 53 ± 12 anos. O HTx teve um efeito significativo na hemodinâmica, com normalização do VE e das pressões de preenchimento de VD e no aumento significativo do débito cardíaco e da freqüência cardíaca (FC). A RVP diminuiu 56% e a CPA aumentou 86%. Em vez de aumentar como era esperado, o RC-time não alterou significativamente e teve papel secundário em relação à normalização da pressão capilar pulmonar (PECP) após o HTx. O aumento esperado no RC timecom PWP reduzido foi atenuado pelo aumento da FC (devido à denervação autonômica do coração). Esse efeito ocorreu independentemente da diminuição da PCPConclusões:O RC-time permaneceu inalterado após HTx, entretanto a PECP diminuiu significativamente. O aumento da FC pode ter impacto importante no RC-time e na pós-carga do VD. O estudo dessas interações pode ser de grande valor para avaliar os candidatos HTx e explicar a falência do VD ocorrida logo após o HTx.