Andreas Martinsson: Heavier donor lungs – increased risk of complications

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ANDREAS MARTINSSON
Dissertation defense: 21 November 2025 (click for details)
Doctoral thesis: Improving Lung Recovery After Cardiac Surgery and Lung Transplantation
Research area: Anesthesiology and Intensive Care
Sahlgrenska Academy, The Institute of Clinical Sciences

After major surgeries, such as heart surgery or lung transplantation, many patients experience reduced lung function. This is often due to parts of the lung temporarily collapsing, known as atelectasis, but in some cases the problems become more severe and require prolonged mechanical ventilation.

– Early after a lung transplant, the new lungs are particularly vulnerable. The oxygen deprivation that occurs when the lung is outside the body, and the subsequent restoration of blood flow, can lead to pulmonary edema characteristic of primary graft dysfunction (PGD) – a serious complication that impairs both recovery and survival, says Andreas Martinsson, consultant in anesthesiology and intensive care and a doctoral student at the Institute of Clinical Sciences.

Different ways to improve lung function

– In the first studies, patients were treated with so-called lung recruitment, either in the supine or prone position, after heart surgery. The treatment was performed immediately after surgery, while the patients were still anesthetized and connected to a ventilator. The method involves temporarily increasing airway pressure to open collapsed areas of the lung. Using electrical impedance tomography (EIT), a gentle imaging technique, the distribution of air within different lung regions could be monitored in real time.

In a subsequent study of patients recovering from acute lung injury associated with heart surgery, two forms of ventilatory support were compared: conventional pressure support and NAVA (Neurally Adjusted Ventilatory Assist), where the ventilator is controlled by the diaphragm’s own electrical signals. A registry analysis examined how donor lung weight – an indirect measure of fluid overload – affected recovery and the risk of PGD.

Photo from the dissertation: A patient being placed in the prone position for lung recruitment after heart surgery. The band around the chest consists of 16 electrodes that measure the lungs’ electrical bioimpedance and create a real-time image of air distribution in different lung regions.

Lung recruitment in the prone position improves oxygenation

Placing the patient in the prone position and performing lung recruitment immediately after heart surgery improved oxygenation and increased air content in the posterior and lower lung regions – the areas where atelectasis most often occurs. The effect persisted even after ventilator treatment was discontinued and was accompanied by a more even distribution of tidal volume throughout the lungs.

– For patients requiring prolonged mechanical ventilation, NAVA showed clear advantages, including improved oxygenation, more efficient carbon dioxide elimination, and a form of ventilatory support that better adapted to the patient’s own breathing pattern.

In lung transplantation, a clear association emerged between high donor lung weight and increased incidence of PGD, poorer oxygenation, longer intensive care stays, and a lower proportion of patients able to breathe without a ventilator within the first 72 hours.

Seeing how research can actually improve care

What has been most rewarding and most challenging about the PhD project?
– The most rewarding part has been combining physiological ideas and advanced technology with tangible patient benefit – seeing how research can actually improve care. In the beginning, the challenge was to define the scientific objectives clearly and to learn the technical systems for measurement and data collection. As the work progressed, maintaining focus became difficult at times, when the path from idea to result was long and filled with revisions before everything finally came together. Balancing research with clinical work is a well-known challenge that I have experienced myself. At the same time, clinical practice forms an essential foundation – it’s where research finds its relevance and its most important questions.

Text: Susanne Lj Westergren