Risk stratification and closed-loop ventilation in critically ill patients

This thesis reports the results of three posthoc analyses on the prognostic value of variables related to oxygenation and ventilation in patients with ARDS, and the results of one non-inferiority randomized clinical trial on the quality of breathing during postoperative ventilation using closed-loop ventilation in patients after cardiac surgery. In the first part of this thesis we focused on the prognostic capacity of the ratio of the arterial oxygen tension (PaO2) or peripheral oxygen saturation (SpO2) to the fraction of inspired oxygen (FiO2), i.e., PaO2/FiO2 or SpO2/FiO2, and the positive end–expiratory pressure for prognostication in mechanically ventilated patients with the acute respiratory distress syndrome at different time-points. Furthermore, we evaluated, whether changes in PaO2/FiO2, deadspace (VD/VT) and driving pressure (ΔP) induced by prone positioning could be used to predict mortality. In the second part we compared the quality of breathing during postoperative ventilation using two different sensor techniques for end–tidal CO2 monitoring with INTELLiVENT–Adaptive Support Ventilation in cardiac surgery patients. We hypothesized that (1) SpO2/FiO2 could be used for risk stratification in patients with ARDS, and that the prognostic capacity would improve over time, (2) changes in PaO2/FiO2, VD/VT, and ΔP induced by prone positioning could be used for predicting mortality, and that (3) the quality of breathing using sidestream capnography is comparable to the quality of breathing using mainstream capnography with postoperative closed-loop ventilation in cardiac surgery patients

Risk stratification and closed-loop ventilation in critically ill patients

This thesis reports the results of three posthoc analyses on the prognostic value of variables related to oxygenation and ventilation in patients with ARDS, and the results of one non-inferiority randomized clinical trial on the quality of breathing during postoperative ventilation using closed-loop ventilation in patients after cardiac surgery. In the first part of this thesis we focused on the prognostic capacity of the ratio of the arterial oxygen tension (PaO2) or peripheral oxygen saturation (SpO2) to the fraction of inspired oxygen (FiO2), i.e., PaO2/FiO2 or SpO2/FiO2, and the positive end–expiratory pressure for prognostication in mechanically ventilated patients with the acute respiratory distress syndrome at different time-points. Furthermore, we evaluated, whether changes in PaO2/FiO2, deadspace (VD/VT) and driving pressure (ΔP) induced by prone positioning could be used to predict mortality. In the second part we compared the quality of breathing during postoperative ventilation using two different sensor techniques for end–tidal CO2 monitoring with INTELLiVENT–Adaptive Support Ventilation in cardiac surgery patients. We hypothesized that (1) SpO2/FiO2 could be used for risk stratification in patients with ARDS, and that the prognostic capacity would improve over time, (2) changes in PaO2/FiO2, VD/VT, and ΔP induced by prone positioning could be used for predicting mortality, and that (3) the quality of breathing using sidestream capnography is comparable to the quality of breathing using mainstream capnography with postoperative closed-loop ventilation in cardiac surgery patients

Induction of severe hypoxemia and low lung recruitability for the evaluation of therapeutic ventilation strategies: a translational model of combined surfactant-depletion and ventilator-induced lung injury

Background: Models of hypoxemic lung injury caused by lavage-induced pulmonary surfactant depletion are prone to prompt recovery of blood oxygenation following recruitment maneuvers and have limited translational validity. We hypothesized that addition of injurious ventilation following surfactant-depletion creates a model of the acute respiratory distress syndrome (ARDS) with persistently low recruitability and higher levels of titrated "best" positive end-expiratory pressure (PEEP) during protective ventilation. Methods: Two types of porcine lung injury were induced by lung lavage and 3 h of either protective or injurious ventilation, followed by 3 h of protective ventilation (N = 6 per group). Recruitment maneuvers (RM) and decremental PEEP trials comparing oxygenation versus dynamic compliance were performed after lavage and at 3 h intervals of ventilation. Pulmonary gas exchange function, respiratory mechanics, and ventilator-derived parameters were assessed after each RM to map the course of injury severity and recruitability. Results: Lung lavage impaired respiratory system compliance (C-rs) and produced arterial oxygen tensions (PaO2) of 84 +/- 13 and 80 +/- 15 (FIO2 = 1.0) with prompt increase after RM to 270-395 mmHg in both groups. After subsequent 3 h of either protective or injurious ventilation, PaO2/FIO2 was 104 +/- 26 vs. 154 +/- 123 and increased to 369 +/- 132 vs. 167 +/- 87 mmHg in response to RM, respectively. After additional 3 h of protective ventilation, PaO2/FIO2 was 120 +/- 15 vs. 128 +/- 37 and increased to 470 +/- 68 vs. 185 +/- 129 mmHg in response to RM, respectively. Subsequently, decremental PEEP titration revealed that C-rs peaked at 36 +/- 10 vs. 25 +/- 5 ml/cm H2O with PEEP of 12 vs. 16 cmH(2)O, and PaO2/FIO2 peaked at 563 +/- 83 vs. 334 +/- 148 mm Hg with PEEP of 16 vs. 22 cmH(2)O in the protective vs. injurious ventilation groups, respectively. The large disparity of recruitability between groups was not reflected in the C-rs nor the magnitude of mechanical power present after injurious ventilation, once protective ventilation was resumed. Conclusion: Addition of transitory injurious ventilation after lung lavage causes prolonged acute lung injury with diffuse alveolar damage and low recruitability yielding high titrated PEEP levels. Mimicking lung mechanical and functional characteristics of ARDS, this porcine model rectifies the constraints of single-hit lavage models and may enhance the translation of experimental research on mechanical ventilation strategies

Year in review in Intensive Care Medicine, 2008: II. Experimental, acute respiratory failure and ARDS, mechanical ventilation and endotracheal intubation

SCOPUS: re.jinfo:eu-repo/semantics/publishe

Transparent decision support for mechanical ventilation using visualization of clinical preferences

BACKGROUND: Systems aiding in selecting the correct settings for mechanical ventilation should visualize patient information at an appropriate level of complexity, so as to reduce information overload and to make reasoning behind advice transparent. Metaphor graphics have been applied to this effect, but these have largely been used to display diagnostic and physiologic information, rather than the clinical decision at hand. This paper describes how the conflicting goals of mechanical ventilation can be visualized and applied in making decisions. Data from previous studies are analyzed to assess whether visual patterns exist which may be of use to the clinical decision maker. MATERIALS AND METHODS: The structure and screen visualizations of a commercial clinical decision support system (CDSS) are described, including the visualization of the conflicting goals of mechanical ventilation represented as a hexagon. Retrospective analysis is performed on 95 patients from 2 previous clinical studies applying the CDSS, to identify repeated patterns of hexagon symbols. RESULTS: Visual patterns were identified describing optimal ventilation, over and under ventilation and pressure support, and over oxygenation, with these patterns identified for both control and support modes of mechanical ventilation. Numerous clinical examples are presented for these patterns illustrating their potential interpretation at the bedside. CONCLUSIONS: Visual patterns can be identified which describe the trade-offs required in mechanical ventilation. These may have potential to reduce information overload and help in simple and rapid identification of sub-optimal settings. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12938-021-00974-5