ABSTRACT
Maintenance of spontaneous effort during mechanical ventilation has long been recognized to improve oxygenation. Such effort has been considered beneficial because oxygenation is a key management aim. However, accumulating evidence indicates that spontaneous effort during mechanical ventilation may cause or worsen acute lung injury. Recently, effort-dependent lung injury has been termed as patient-self inflicted lung injury (P-SILI). This paper describes pathophysiological changes of ventilation-induced lung injury (VILI) induced by mechanical ventilation and spontaneous breathing, and the role of spontaneous breathing during mechanical ventilation in acute respiratory distress syndrome (ARDS). Studies have shown that spontaneous breathing is a double-edged sword, depending on the intensity of spontaneous breathing activity and the severity of lung injury. Future studies are needed to determine ventilator strategies minimizing injury.
ABSTRACT
Heart transplantation can save the life and improve the quality of life of patients with end-stage heart failure. Nevertheless, it is not suitable for all patients with end-stage heart failure. As a common complication of end-stage heart failure, pulmonary artery hypertension may increase the incidence of right heart failure after heart transplantation, which is associated with the short- and long-term fatality risk in the recipients after heart transplantation. In clinical practice, different transplant centers have different criteria for heart transplantation indications in patients with end-stage heart failure complicated with pulmonary artery hypertension. Accurate preoperative evaluation of surgical indications plays a critical role in determining the success of heart transplantation. In this article, the definition, pathogenesis and effects on heart transplantation, diagnostic methods and reversibility judgment of pulmonary artery hypertension, diagnostic treatment of reversible pulmonary artery hypertension and indications of heart transplantation in patients with end-stage heart failure complicated with reversible pulmonary hypertension were reviewed.
ABSTRACT
Esophageal pressure monitoring provides a minimally invasive method to assess the pleural pressure, which can be used to differentiate the lung and chest wall mechanics. The information of transpulmonary pressure, work of breathing, intrinsic positive end-expiratory pressure and respiratory muscle performance can facilitate the proper setting of mechanical ventilation. Esophageal pressure monitoring is still not routinely used in the clinical setting because of difficulty in esophageal balloon catheter placement and data interpretation due to esophageal pressure monitoring has certain technical requirements, and the measurement results are influenced by many factors such as airbag volume, location, esophageal wall elasticity and mediastinal organ weight. In this review, we introduced technique for esophageal pressure measurement and calculation of transpulmonary pressure aiming to promote the clinical application of esophageal pressure monitoring.
ABSTRACT
Objective To evaluate the value of transpulmonary pressure (Ptp) guided optimal positive end-expiratory pressure (PEEP) selection in patients with early acute respiratory distress syndrome (ARDS).Methods A prospective randomized self-control study was conducted.ARDS patients in the early stage (onset ≤3 days) undergoing intubation and mechanical ventilation admitted to intensive care unit (ICU) of Jiangsu Provincial Subei People's Hospital from December 2013 to December 2015 were enrolled.The PEEP level was regulated to 30 cmH2O (1 cmH2O =0.098 kPa) after recruitment maneuver,and then it was gradually decreased to 0 with lowering by 3 cmH2O every 5 minutes.The optimal PEEP was titrated by Ptp,lowest dead space fraction (VD/VT),highest static lung compliance (Cst),and optimal oxygenation,respectively.Parameters of respiratory mechanics and gas exchange were observed.Results Totally 28 patients with ARDS (including 17 male and 11 female) were included with the average age of (45 ± 12) years old,acute physiology and chronic health evaluation Ⅱ (APACHE Ⅱ) score was 21 ± 9,oxygenation index (PaO2/FiO2) was (165 ± 76) mmHg (1 mmHg =0.133 kPa).① During decremental PEEP titration,Ptp was gradually decreased,and expiratory Ptp (Ptp-e) was more than zero [(1.3±0.3) cmH2O] when PEEP was (9.6 ± 2.3) cmH2O.Cst was initially improved until reaching a peak,and then deteriorated.Cst was highest [(50 ± 8) mL/cmH2O] when PEEP was (11.5 ± 2.4) cmH2O.PaO2/FiO2 reached the maximum [(312 ± 99) mmHg] at PEEP level of (18.0 ± 2.5) cmH2O.Compared with Ptp-e 3.00-5.99 cmH2O,PaO2/FiO2 was significantly decreased when Ptp-e became negative (all P ＜ 0.05).VD/VT was lowest (0.52 ±0.05) when PEEP was (10.1 ± 2.2) cmH2O.When compared with ventilation [inspiratory Ptp (Ptp-i) 0-2.99 cmH2O],it was significantly higher during high (Ptp-i ≥ 15 cmH2O,all P ＜ 0.05).② There were no statistically significant differences in the levels of optimal PEEP,Ptp-i and Ptp-e among Ptp,lowest VD/VT and highest Cst methods (all P ＞ 0.05),but they were significantly less than optimal oxygenation method (all P ＜ 0.05).Compared with baseline and the method of optimal oxygenation,Cst in other three PEEP titration methods including Ptp,lowest VD/VT and highest Cst was improved obviously (mL/cmH2O:46± 7,47±9,50± 8 vs.30± 8,35 ± 10,all P ＜ 0.05).PaO2/FiO2 (mmHg) in the method of Ptp and lowest VD/VT were higher than the baseline (252 ± 86,258 ± 72 vs.165 ± 76,both P ＜ 0.05),but significantly lower than that of optimal oxygenation method (312 ± 99,both P ＜ 0.05),and did not significantly differ from that of highest Cst (268± 85,both P ＞ 0.05).Compared with baseline and the method of optimal oxygenation,VD/Vr improved significantly in ventilated patients on PEEP targeting with Ptp and lowest VD/VT (0.53±0.05,0.52±0.05 vs.0.59±0.05,0.58±0.04,all P ＜ 0.05).Conclusion Titration the optimal PEEP level with the method of Ptp could promote collapse alveolar recruitment,improve oxygenation and lung compliance,decrease dead space ventilation,and will not cause alveolar excessive inflation in patients who undergoing mechanical ventilation with early ARDS.
ABSTRACT
Esophageal pressure(Pes)is usually measured via a catheter with an air - filled thin - walled latex balloon inserted nasally or orally. To validate Pes measurement,a dynamic occlusion test measures the ratio of change in Pes to change in Paw during inspiratory efforts against a closed airway. This report summarizes current physiological and technical knowledge on esophageal pressure measurements in patients receiving mechanical ventilation. The respiratory changes in Pes are representative of changes in pleural pressure. The difference between airway pressure(Paw)and Pes is a valid estimate of transpulmonary pressure. Because of the nonuniformity of lesion of pulmonary in patient with acute respiratory distress syndrome,Paw and volume can not represent the stress to expand the pulmonary. How to adjust posi-tive end expiratory pressure(PEEP)is still lack of gold standard. The use of Pes for PEEP titration may help improve oxygenation and compliance,or even has the possibility to improve the patient outcome.