Continuous and bilevel positive airway pressure may improve radiotherapy delivery in patients with intra-thoracic tumors

J Elshof; C M Steenstra; A G H Niezink; P J Wijkstra; R Wijsman; M L Duiverman

doi:10.1016/j.ctro.2024.100784

Continuous and bilevel positive airway pressure may improve radiotherapy delivery in patients with intra-thoracic tumors

Clin Transl Radiat Oncol. 2024 Apr 20:47:100784. doi: 10.1016/j.ctro.2024.100784. eCollection 2024 Jul.

Authors

J Elshof^{1

2}, C M Steenstra^{1

2}, A G H Niezink³, P J Wijkstra^{1

2}, R Wijsman³, M L Duiverman^{1

2}

Affiliations

¹ Department of Pulmonary Diseases/Home Mechanical Ventilation, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
² Groningen Research Institute for Asthma and COPD, University of Groningen, Groningen, The Netherlands.
³ Department of Radiation Oncology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.

Abstract

Background: Minimizing tumor motion in radiotherapy for intra-thoracic tumors reduces side-effects by limiting radiation exposure to healthy tissue. Continuous or Bilevel Positive Airway Pressure (CPAP/BiPAP) could achieve this, since it could increase lung inflation and decrease tidal volume variability. We aim to identify the better CPAP/BiPAP setting for minimizing tumor motion.

Methods: In 10 patients (5 with lung cancer, 5 with other intra-thoracic tumors), CPAP/BiPAP was tested with the following settings for 10 min each: CPAP 5, 10 and 15 cmH₂O and BiPAP 14/10 cmH₂O with a lower (7 breaths/min) and higher back-up respiratory rate (BURR initially 1 breath/min above the spontaneous breathing frequency, with the option to adjust if the patient continued to initiate breaths). Electrical impedance tomography was used to analyse end-expiratory lung impedance (EELI) as an estimate of end-expiratory lung volume and tidal impedance variation (TIV) as an estimate of tidal volume.

Results: Nine out of ten patients tolerated all settings; one patient could not sustain CPAP-15. A significant difference in EELI was observed between settings (χ² 22.960, p < 0.001), with most increase during CPAP-15 (median (IQR) 1.03 (1.00 - 1.06), normalized to the EELI during spontaneous breathing). No significant differences in TIV and breathing variability were found between settings.

Conclusions: This study shows that the application of different settings of CPAP/BiPAP in patients with intra-thoracic tumors is feasible and tolerable. BiPAP with a higher BURR may offer the greatest potential for mitigating tumor motion among the applied settings, although further research investigating tumor motion should be conducted.

Keywords: BiPAP; CPAP; Non-invasive ventilation; Radiotherapy.