Browsing by Author "Adler, Andy"
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- ItemElectrical impedance tomography monitoring in adult ICU patients: state-of-the-art, recommendations for standardized acquisition, processing, and clinical use, and future directions(2024) Scaramuzzo, Gaetano; Pavlovsky, Bertrand; Adler, Andy; Baccinelli, Walter; Bodor, Dani L.; Damiani Rebolledo, L. Felipe; Franchineau, Guillaume; Francovich, Juliette; Frerichs, Inéz; Sánchez Giralt, Juan A.; Grychtol, Bartłomiej; He, Huaiwu; Katira, Bhushan H.; Koopman, Alette A.; Leonhardt, Steffen; Menga, Luca S.; Mousa, Amne; Pellegrini, Mariangela; Piraino, Thomas; Priani, Paolo; Somhorst, Peter; Spinelli, Elena; Händel, Claas; Suárez-Sipmann, Fernando; Wisse, Jantine J.; Becher, Tobias; Jonkman, Annemijn H.Electrical impedance tomography (EIT) is an emerging technology for the non-invasive monitoring of regional distribution of ventilation and perfusion, offering real-time and continuous data that can greatly enhance our understanding and management of various respiratory conditions and lung perfusion. Its application may be especially beneficial for critically ill mechanically ventilated patients. Despite its potential, clear evidence of clinical benefits is still lacking, in part due to a lack of standardization and transparent reporting, which is essential for ensuring reproducible research and enhancing the use of EIT for personalized mechanical ventilation. This report is the result of a four-day expert meeting where we aimed to promote the consistent and reliable use of EIT, facilitating its integration into both clinical practice and research, focusing on the adult intensive care patient. We discuss the state-of-the-art regarding EIT acquisition and processing, applications during controlled ventilation and spontaneous breathing, ventilation-perfusion assessment, and novel future directions.
- ItemOptimization of lung ventilation and perfusion in anesthetized horses using a ventilation mode with flow-limited expiration(2024) Araos, Joaquin; Driessen, Bernd; Brandly, Jerrianne; Gorenberg, Emma; Heerdt, Paul; Bruhn, Alejandro; Martin-Flores, Manuel; Adler, Andy; Hopster, KlausOBJECTIVE To investigate the mechanisms underlying the improved arterial oxygenation described with flow-limited expiration (FLEX) ventilation in anesthetized horses. ANIMALS 5 healthy adult research horses. METHODS Horses underwent volume-controlled ventilation for 60 minutes (VCV (1) ), followed by 60 minutes of FLEX, and 30 minutes of VCV (VCV (2) ). Main outcomes included the arterial partial pressure of oxygen-to-F io(2) (PF) ratio and electrical impedance tomography (EIT)-derived functional indices at the end of each phase. The EIT data were used to create regional maps of relative lung ventilation and perfusion as well as regional maps of ventilation/perfusion (V/Q) ratios. Ventilation indices derived from EIT included the fraction of expired volume in 1 second (FEV (1) ; %) and the time it took for the EIT signal to drop to 50% of the peak signal at end -inspiration (T- Close 50; seconds). Data were analyzed with 2-way ANOVA for repeated measures. P < .05 was considered significant. RESULTS The PF ratio increased significantly with FLEX compared to both VCV (1) and VCV (2) ( P < .01). There were no differences in the relative distribution of ventilation nor perfusion between ventilation strategies. However, when ventilation and perfusion were superimposed and V/Q ratio maps were constructed, FLEX had a homogenizing effect toward values of 1.0. The FEV (1) was shorter ( P < .01) and the T Close 50 was longer ( P < .001) in all regions during FLEX compared to both VCV (1) and VCV (2) . CLINICAL RELEVANCE Our findings suggest that FLEX ventilation in anesthetized horses enhances regional V/Q matching, likely by pro - longing expiratory aeration and reducing airway closure.
- ItemPreliminary evaluation of the effects of a 1:1 inspiratory-to-expiratory ratio in anesthetized and ventilated horses(2022) Pittman, Ella; Martin-Flores, Manuel; Mosing, Martina; Lorenzutti, Matías; Retamal Montes, Jaime; Staffieri, Francesco; Adler, Andy; Campbell, Mark; Araos, JoaquínObjective: To describe some cardiorespiratory effects of an inspiratory-to-expiratory (IE) ratio of 1:1 compared with 1:3 in ventilated horses in dorsal recumbency. Study design: Randomized crossover experimental study. Animals: A total of eight anesthetized horses, with 444 (330–485) kg body weight [median (range)]. Methods: Horses were ventilated in dorsal recumbency with a tidal volume of 15 mL kg–1 and a respiratory rate of 8 breaths minute–1, and IE ratios of 1:1 (IE1:1) and 1:3 (IE1:3) in random order, each for 25 minutes after applying a recruitment maneuver. Spirometry, arterial blood gases and dobutamine requirements were recorded in all horses during each treatment. Electrical impedance tomography (EIT) data were recorded in four horses and used to generate functional EIT variables including regional ventilation delay index (RVD), a measure of speed of lung inflation, and end-expiratory lung impedance (EELI), an indicator of functional residual capacity (FRC). Results were assessed with linear and generalized linear mixed models. Results: Compared with treatment IE1:3, horses ventilated with treatment IE1:1 had higher mean airway pressures and respiratory system compliance (p < 0.014), while peak, end-inspiratory and driving airway pressures were lower (p < 0.001). No differences in arterial oxygenation or dobutamine requirements were observed. PaCO2 was lower in treatment IE1:1 (p = 0.039). Treatment IE1:1 resulted in lower RVD (p < 0.002) and higher EELI (p = 0.023) than treatment IE1:3. Conclusions and clinical relevance: These results suggest that IE1:1 improved respiratory system mechanics and alveolar ventilation compared with IE1:3, whereas oxygenation and dobutamine requirements were unchanged, although differences were small. In the four horses where EIT was evaluated, IE1:1 led to a faster inflation rate of the lung, possibly the result of increased FRC. The clinical relevance of these findings needs to be further investigated.
- ItemThree-dimensional electrical impedance tomography (EIT) to study regional ventilation/perfusion (V/Q̇) ratios in anesthetized pigs(Research Square, 2023) Larrabee, Shannon; Nugen, Sarah; Bruhn, Alejandro; Stowe, Symon; Adler, Andy; Martin-Flores, Manuel; Araos, JoaquinThis study aimed to develop a 3D method for assessing V/Q̇ ratios in a pig model of hemodynamic perturbations using electrical impedance tomography (EIT). In order to evaluate whether the physiological coherence of changes in EIT-derived V/Q̇ ratios, global EIT-derived V/Q̇ mismatch were compared with global gold-standards. The study found regional heterogeneity in the distribution of V/Q̇ ratios in both the ventrodorsal and craniocaudal directions. Although global EIT-derived indices of V/Q̇ mismatch consistently underestimated both low and high V/Q̇ mismatch compared to global gold standards, the direction of the change was similar. We have made the software available at no cost for other researchers to use. Future studies should compare regional V/Q̇ ratios determined by our method against other regional, high-resolution methods such as SPECT or PET scan.
- ItemThree-dimensional electrical impedance tomography to study regional ventilation/perfusion ratios in anesthetized pigs(2023) Larrabee, Shannon; Nugen, Sarah; Bruhn, Alejandro; Porter, Ian; Stowe, Symon; Adler, Andy; Martin-Flores, Manuel; Araos, JoaquinThis study aimed to develop a three-dimensional (3-D) method for assessing ventilation/perfusion (V/Q) ratios in a pig model of hemodynamic perturbations using electrical impedance tomography (EIT). To evaluate the physiological coherence of changes in EIT-derived V/Q ratios, global EIT-derived V/Q mismatches were compared with global gold standards. The study found regional heterogeneity in the distribution of V/Q ratios in both the ventrodorsal and craniocaudal directions. Although global EIT-derived indices of V/Q mismatch consistently underestimated both low and high V/Q mismatch compared with global gold standards, the direction of the change was similar. We made the software available at no cost for other researchers to use. Future studies should compare regional V/Q ratios determined by our method against other regional, high-resolution methods.