Effects of Prone Positioning on Respiratory Mechanics and Oxygenation in Critically Ill Patients With COVID-19 Requiring Venovenous Extracorporeal Membrane Oxygenation

Background:The effect of prone positioning (PP) on respiratory mechanics remains uncertain in patients with severe acute respiratory distress syndrome (ARDS) requiring venovenous extracorporeal membrane oxygenation (VV-ECMO).Methods:We prospectively analyzed the effects of PP on respiratory mechanics from continuous data with over a thousand time points during 16-h PP sessions in patients with COVID-19 and ARDS under VV-ECMO conditions. The evolution of respiratory mechanical and oxygenation parameters during the PP sessions was evaluated by dividing each PP session into four time quartiles: first quartile: 0–4 h, second quartile: 4–8 h, third quartile: 8–12 h, and fourth quartile: 12–16 h.Results:Overall, 38 PP sessions were performed in 10 patients, with 3 [2–5] PP sessions per patient. Seven (70%) patients were responders to at least one PP session. PP significantly increased the PaO2/FiO2 ratio by 14 ± 21% and compliance by 8 ± 15%, and significantly decreased the oxygenation index by 13 ± 18% and driving pressure by 8 ± 12%. The effects of PP on respiratory mechanics but not on oxygenation persisted after supine repositioning. PP-induced changes in different respiratory mechanical parameters and oxygenation started as early as the first-time quartile, without any difference in PP-induced changes among the different time quartiles. PP-induced changes in driving pressure (−14 ± 14 vs. −6 ± 10%, p = 0.04) and mechanical power (−11 ± 13 vs. −0.1 ± 12%, p = 0.02) were significantly higher in responders (increase in PaO2/FiO2 ratio > 20%) than in non-responder patients.Conclusions:In patients with COVID-19 and severe ARDS, PP under VV-ECMO conditions improved the respiratory mechanical and oxygenation parameters, and the effects of PP on respiratory mechanics persisted after supine repositioning.

Assessing the Asynchrony Event Based on the Ventilation Mode for Mechanically Ventilated Patients in ICU

Respiratory system modelling can assist clinicians in making clinical decisions during mechanical ventilation (MV) management in intensive care. However, there are some cases where the MV patients produce asynchronous breathing (asynchrony events) due to the spontaneous breathing (SB) effort even though they are fully sedated. Currently, most of the developed models are only suitable for fully sedated patients, which means they cannot be implemented for patients who produce asynchrony in their breathing. This leads to an incorrect measurement of the actual underlying mechanics in these patients. As a result, there is a need to develop a model that can detect asynchrony in real-time and at the bedside throughout the ventilated days. This paper demonstrates the asynchronous event detection of MV patients in the ICU of a hospital by applying a developed extended time-varying elastance model. Data from 10 mechanically ventilated respiratory failure patients admitted at the International Islamic University Malaysia (IIUM) Hospital were collected. The results showed that the model-based technique precisely detected asynchrony events (AEs) throughout the ventilation days. The patients showed an increase in AEs during the ventilation period within the same ventilation mode. SIMV mode produced much higher asynchrony compared to SPONT mode (p < 0.05). The link between AEs and the lung elastance (AUC Edrs) was also investigated. It was found that when the AEs increased, the AUC Edrs decreased and vice versa based on the results obtained in this research. The information of AEs and AUC Edrs provides the true underlying lung mechanics of the MV patients. Hence, this model-based method is capable of detecting the AEs in fully sedated MV patients and providing information that can potentially guide clinicians in selecting the optimal ventilation mode of MV, allowing for precise monitoring of respiratory mechanics in MV patients.

FUNCTIONAL LIMITATIONS ARISING FROM CHANGES IN RESPIRATORY MECHANICS IN CHRONIC OBSTRUCTIVE PULMONARY DYSFUNCTION

(INTRODUCTION) chronic obstructive pulmonary disease is a common preventable and treatable disease where an obstruction leads to various respiratory changes such as impaired airflow, leading to several changes occurring in the mechanics of the respiratory muscles, alters the conformation of the chest and diaphragm, mainly causing dyspnea and limitations as limitations. This research aims to correlate limitations according to changes in respiratory mechanics. (MATERIALS AND METHODS) the present is an integrative literature review, for the search for articles were used as databases PUBMED and SCIELO, studies were included without distinction of language and year, published and indexed in the databases free of charge and in full, studies that associated COPD with other respiratory diseases were excluded, studies where the reserves had undergone lung surgery, and studies that did not bring complete results. (RESULTS) 52 studies were found in total, 15 duplicates were excluded, in the first selection stage 19 studies were excluded, in the second stage 10 studies were excluded, thus the review sample of 9 studies, of the clinical trial type. (CONCLUDING REMARKS) Among the most prevalent limitations we saw low tolerance and resistance to physical exercises, limitations to perform activities of daily living, leading to dyspnea and dysfunction of the respiratory muscles, affecting the happy quality of life.

Positive end-expiratory pressure in COVID-19 acute respiratory distress syndrome: the heterogeneous effects

Background We hypothesized that as CARDS may present different pathophysiological features than classic ARDS, the application of high levels of end-expiratory pressure is questionable. Our first aim was to investigate the effects of 5–15 cmH2O of PEEP on partitioned respiratory mechanics, gas exchange and dead space; secondly, we investigated whether respiratory system compliance and severity of hypoxemia could affect the response to PEEP on partitioned respiratory mechanics, gas exchange and dead space, dividing the population according to the median value of respiratory system compliance and oxygenation. Thirdly, we explored the effects of an additional PEEP selected according to the Empirical PEEP-FiO2 table of the EPVent-2 study on partitioned respiratory mechanics and gas exchange in a subgroup of patients. Methods Sixty-one paralyzed mechanically ventilated patients with a confirmed diagnosis of SARS-CoV-2 were enrolled (age 60 [54–67] years, PaO2/FiO2 113 [79–158] mmHg and PEEP 10 [10–10] cmH2O). Keeping constant tidal volume, respiratory rate and oxygen fraction, two PEEP levels (5 and 15 cmH2O) were selected. In a subgroup of patients an additional PEEP level was applied according to an Empirical PEEP-FiO2 table (empirical PEEP). At each PEEP level gas exchange, partitioned lung mechanics and hemodynamic were collected. Results At 15 cmH2O of PEEP the lung elastance, lung stress and mechanical power were higher compared to 5 cmH2O. The PaO2/FiO2, arterial carbon dioxide and ventilatory ratio increased at 15 cmH2O of PEEP. The arterial–venous oxygen difference and central venous saturation were higher at 15 cmH2O of PEEP. Both the mechanics and gas exchange variables significantly increased although with high heterogeneity. By increasing the PEEP from 5 to 15 cmH2O, the changes in partitioned respiratory mechanics and mechanical power were not related to hypoxemia or respiratory compliance. The empirical PEEP was 18 ± 1 cmH2O. The empirical PEEP significantly increased the PaO2/FiO2 but also driving pressure, lung elastance, lung stress and mechanical power compared to 15 cmH2O of PEEP. Conclusions In COVID-19 ARDS during the early phase the effects of raising PEEP are highly variable and cannot easily be predicted by respiratory system characteristics, because of the heterogeneity of the disease.

Effects on Lung Gas Volume, Respiratory Mechanics and Gas Exchange of a Closed-Circuit Suctioning System during Volume- and Pressure-Controlled Ventilation in ARDS Patients

Mechanically ventilated patients periodically require endotracheal suctioning. There are conflicting data regarding the loss of lung gas volume caused by the application of a negative pressure by closed-circuit suctioning. The aim of this study was to evaluate the effects of suctioning performed by a closed-circuit system in ARDS patients during volume- or pressure-controlled ventilation. In this prospective crossover-design study, 18 ARDS patients were ventilated under volume and pressure control applied in random order. Gas exchange, respiratory mechanics and EIT-derived end-expiratory lung volume (EELV) before the suctioning manoeuvre and after 5, 15 and 30 min were recorded. The tidal volume and respiratory rate were similar in both ventilation modes; in volume control, the EELV decreased by 31 ± 23 mL, 5 min after the suctioning, but it remained similar after 15 and 30 min; the oxygenation, PaCO2 and respiratory system elastance did not change. In the pressure control, 5 min after suctioning, EELV decreased by 35 (26–46) mL, the PaO2/FiO2 did not change, while PaCO2 increased by 5 and 30 min after suctioning (45 (40–51) vs. 48 (43–52) and 47 (42–54) mmHg, respectively). Our results suggest minimal clinical advantages when a closed system is used in volume-controlled compared to pressure-controlled ventilation.

Sealing-type Three-cavities Ventilation Joint: A New Device in Painless Bronchoscopy

Background: To observe the clinical effect and safety of the sealing-type three-cavities ventilation joint in painless bronchoscopy. To compare the respiratory mechanics between I-gel laryngeal mask and tracheal tube-controlled breath during bronchoscopy. Methods: 200 patients underwent bronchoscopy were recruited and randomly assigned to general anesthesia group (group Ⅰ, n = 100) and local anesthesia group (group Ⅱ, n = 100). General anesthesia group were divided into two groups, the I-gel laryngeal mask combined with sealing-type three-cavities ventilation joint group group(n=50) and the endotracheal tube combined with sealing-type three-cavities ventilation joint group(n=50). Patients in Group I were adopted by I-gel laryngeal mask or endotracheal tube with the sealing-type three-cavities ventilation joint after the induction anesthesia with remifentanil, propofol and succinylcholine. In group II, patients were anaesthetized with lidocaine and followed by 2mg/ kg propofol iv, and spontaneous respirations were retained with nasal cannula. All patients’ vital signs, endoscopic related adverse reactions and arterial blood gas analysis were recorded during the procedure. Results: Group I showed little changes of vital signs (P <0.05), and less adverse reaction such as the intraoperative hypoxia and intraoperative body movement (P <0.05), and no significant decrease of oxygen partial pressure (P <0.05). There is no significant difference in respiratory mechanics including tidal volume and airway pressure between two subgroups in group I(P>0.05). Conclusion: Sealing-type three-cavities ventilation joint prevents the oxygen deficit and makes it possible for us to examine patients through bronchoscope under general anesthesia without gas leakage. Moreover, sealing-type three-cavities ventilation joint provides safe and effective airway control while it does not change respiratory mechanics in endotracheal tube group compared with I-gel laryngeal mask makes endotracheal tube an alternative solution in bronchoscope. Take all these in consideration, sealing-type three-cavities ventilation joint proves to be a feasible method in bronchoscope.