Restoring Pulmonary Function

People suffering from lung disease temporarily need ventilator support because they are unable to breathe naturally. Mechanical ventilation is designed to ensure the survival of these patients. The goal is to adapt the ventilator settings and tailor them the patient's specific needs and prevent lung tissue damage.

In this interview with MEDICA-tradefair.com, Christian Bozsak talks about the features of the Pulmo Vista 500 electrical impedance tomography (EIT) machine, explains the advantages the device offers both patients and physicians and reveals the groundbreaking EIT qualities that pave the way for future developments in image-guided lung protection.

Electrical impedance tomography (EIT) refers to respiratory monitoring that observes differences in the regional air distribution within the lungs via electrodes that are attached to the chest. What diseases can EIT monitor?

Christian Bozsak: EIT is used in clinical facilities whenever physicians need to obtain a detailed real-time overview of regional lung function changes in mechanically ventilated patients. Typical disease patterns include acute respiratory distress syndrome or pneumonia. Ultimately, EIT helps to make the best diagnosis and facilitates personalized ventilation treatment. EIT enables physicians to make customized PEEP (positive end-expiratory pressure) ventilator adjustments, which prevents overinflation or collapse of the patient’s lungs. Both are undesired adverse effects of mechanical ventilation, which can result in lung injury, might subsequently impede the patient's health and lead to prolonged hospital stays.

What are the advantages of EIT compared to other lung imaging tests?

Bozsak: EIT measurements with the PulmoVista500 machine can be performed in real-time and directly at bedside, meaning patients don’t have to be transferred to another location to undergo the procedure. The device measures at up to 50 frames per second in real-time, thus facilitating the continuous monitoring of tidal volume distribution in the patient's lungs- unlike CT (computed tomography). Even though CT gives an accurate view of the morphology of the lungs, the scan is merely a snapshot. Changes can only be detected with a second scan. That’s why EIT is a valuable complement to radiology techniques. In addition to facilitating optimal ventilation settings, EIT can also be used to give direct feedback on the treatment success of mechanically ventilated patents for a variety of intervention therapies.

PulmoVista 500 is an electrical impedance tomograph designed by your company. In addition to image rendering, it can generate global and regional impedance waveforms and parameters in real-time, with the global parameters reflecting the condition of the lung as a whole and the regional ones measuring lung function in different areas of the lung. What types of impedances and parameters are these exactly?

Bozsak: PulmoVista 500 provides continuous information on the regional distribution of ventilation, represented as dynamic images, curves and parameters. This is based on measurements of the electrical resistance of the chest. The EIT screen provides trend views on regional air distribution and changes of end-expiratory lung volume (at the end of normal expiration). Thanks to the latest 1.2 software update from early 2018, PulmoVista can – among other things- directly indicate whether lung regions collapse or overinflate at specific PEEP settings. Regions in orange color indicate a decrease in compliance due to higher pressure and point to an impending overinflation of the lungs. Meanwhile, white-colored regions indicate a higher risk of collapse. The software helps to determine the optimal PEEP ventilation setting for the individual patient.

What is the purpose of the global and regional parameters?

Bozsak: Global parameters such as tidal variation or changes in end-expiratory lung volumes indicate trends of the condition of the lung as a whole. Regional information can indicate regional lung compliance or show how different lung regions respond to therapeutic interventions over time. The added benefit of EIT is that it visualizes regional effects within the lungs and thus may support the early detection and prevention of mechanical pulmonary injury. Regional compliance changes and time parameters can be summed up thanks to the image and enable an assessment of the overall situation.

What are the benefits of PulmoVista 500 for patients?

Bozsak: Inaccurate treatment settings in artificial respiration can result in lung injury or even multiple organ failure. That’s why information on regional air distribution within the lungs is crucial when you treat patients with mechanical ventilation. What’s more, transportation from one hospital facility to another can likewise lead to complications. In our setting, there is no need for patient transport since EIT measurements are performed at bedside. PulmoVista500 monitoring is also non-invasive and –unlike chest x-rays or CT scans (computed tomography) - does not require ionizing radiation. Initial studies have shown that EIT-guided respiratory support leads to improved oxygenation and respiratory mechanism. Potentially harmful effects of mechanical ventilation can be reduced, which makes it easier for patients to wean off the ventilator support. Ultimately, patients can benefit from ventilator support that is tailored to their individual needs.

Can PulmoVista 500 measurements cause any side effects for patients?

Bozsak: PulmoVista 500 electrode measurement involves the application of minor current in the chest to measure the resulting impedance. Impedance changes depending on the air content in the lungs, resulting in a tomographic image. Since the EIT measurements don’t require any further radiation, there are no side effects.

Which features should further advances in EIT include?

Bozsak: EIT is in the process of becoming an integral part of routine medical procedure as evidenced by the fact that its use has been defined in clinical guidelines, while it received its own current procedural terminology (CPT) code in January 2019. Our latest 1.20 software update "Diagnostics" provides a distinct, standardized approach for finding the optimal personalized PEEP setting for mechanically ventilated patients. Future developments will build on our image-guided lung protection approach and commit to answering additional concrete clinical questions specific to mechanical ventilation.