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

TL;DR

Using CPAP and BiPAP in patients with chest tumors is feasible and may help reduce tumor movement during radiotherapy.

Contribution

Demonstrates that BiPAP with a higher backup respiratory rate may be more effective than CPAP in reducing tumor motion during radiotherapy.

Findings

Nine out of ten patients tolerated CPAP and BiPAP settings without major issues.

CPAP-15 showed the highest increase in end-expiratory lung volume.

BiPAP with a higher backup respiratory rate may offer the best potential for reducing tumor motion.

Abstract

•Application of CPAP and BiPAP in patients with intra-thoracic tumors is feasible and tolerable.•Both CPAP and BiPAP may increase end-expiratory lung volume.•Notably, BiPAP with a frequency 3.5 breath/min above spontaneous breathing shows promise, as it may reduce tidal volumes.

Application of CPAP and BiPAP in patients with intra-thoracic tumors is feasible and tolerable.

Both CPAP and BiPAP may increase end-expiratory lung volume.

Notably, BiPAP with a frequency 3.5 breath/min above spontaneous breathing shows promise, as it may reduce tidal volumes.

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.

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.

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.

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.

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