[Influence of varying frequency parameters in high-frequency oscillatory ventilation on the therapeutic efficacy of heavy ion radiotherapy in patients with thoracic and abdominal neoplasms: a prospective randomized controlled trial].

Abstract

Objective: To explore the effects and prognosis of heavy ion therapy for thoracic and abdominal malignant tumors under different frequency settings of high-frequency oscillatory breathing control. Methods: A prospective randomized controlled trial was conducted on 45 patients with thoracic and abdominal malignant tumors who received heavy ion therapy under high-frequency oscillatory ventilation (HFOV) control at Gansu Wuwei Tumour Hospital from January 2023 to December 2024. The patients were randomly divided into three groups by block randomization, with 15 patients in each group, and they received different HFOV frequency settings (6 Hz, 7 Hz and 8 Hz, i.e., 360 breaths/min, 420 breaths/min and 480 breaths/min), while other parameters were kept constant (oxygen concentration: 40%, mean airway pressure: 10 cmH₂O, amplitude: 6cm). The arterial blood gas, transcutaneous carbon dioxide partial pressure/transcutaneous oxygen partial pressure (TcPCO₂/TcPO₂), duration of HFOV ventilation, duration of invasive mechanical ventilation, length of hospital stay and complications of the patients under different frequency settings were analyzed. Results: Before and after treatment, there was no statistically significant difference in arterial blood gas parameters (PaCO₂, PaO₂), oxygenation index, blood lactate, bicarbonate ion) among the 6 Hz,7 Hz and 8 Hz HFOV frequency groups (all P＞0.05). At 30 minutes, 60 minutes, 120 minutes of treatment and at extubation, there was no statistically significant difference in TcPCO₂, TcPO₂, SpO₂ and heart rate among the 6 Hz, 7 Hz and 8 Hz HFOV frequency groups (all P＞0.05). The HFOV duration of the 6 Hz, 7 Hz and 8 Hz HFOV frequency groups was (131.7±8.4) minutes, (125.3±6.9) minutes and (115.7±10.5) minutes, respectively; the duration of invasive mechanical ventilation was (212.3±21.2) minutes, (190.7±14.8) minutes and (199.3±18.4) minutes, respectively; the tumor shrinkage rate was (53.1±6.1)%, (64.7±5.1)% and (63.0±6.2)%, respectively; and the hospital stay was (22.7±2.9) days, (22.3±3.1) days and (20.8±3.3) days, respectively. There was no statistically significant difference among the groups (all P＞0.05). Only one patient developed reversible hypercapnia, which returned to the normal range within 30 minutes after adjusting the invasive ventilator parameters. No treatment-related adverse events such as hypoxemia, radiation pneumonitis, or hemodynamic instability occurred in any of the subjects. Conclusions: HFOV management under heavy ion therapy for thoracoabdominal malignancies shows no significant changes in arterial blood gas analysis before and after treatment at different frequencies (6 Hz, 7 Hz, 8 Hz). Continuous monitoring of transcutaneous TcPCO₂/TcPO₂ is stable. The treatment process is safe, with few complications and good results.