Defining short and prolonged breath-holds.

In Khot et al.’s interesting recent paper in the British Journal of Radiology,[1] they describe breath-hold durations of 36 s with maximum inspirations of air as “prolonged breath-holding”. Breath-holding is indeed increasingly applied to mitigate the effects of respiratory motion, both in radiology to improve the imaging and in radiotherapy to decrease the margins. In breast cancer radiotherapy,[2] it is also used to expand the lung volume to avoid irradiation of the heart. Here, the breath-holds with air are described as multiple (5–10), “short” breath-holds (20–30 s) and are sometimes called deep inspiratory breath-holds.

For radiotherapy, we have demonstrated the feasibility of 60 s breath-holds of air to immobilize the pancreas.[3] Furthermore, we have also developed techniques involving preoxygenation and hypocapnia to enable breast cancer patients to achieve safely “prolonged” breath-holds (>5 min),[4] and for healthy volunteers to perform multiple “prolonged” breath-holds (nine successive breath-holds of >4 min).[5]

The descriptions of “short” and “prolonged” breath-holds are becoming increasingly confusing. It seems therefore important to adopt consistent terminology for medical imaging and radiotherapy.

We propose that breath-holds achieved with air (durations typically less than 1 min and best measured in the order of seconds) are described as “short”.[1-3] Whereas breath-holds achieved with preoxygenation and hypocapnia (durations best measured in the order of minutes) are described as “prolonged”.[4,5]