Effects of unilateral superimposed high-frequency jet ventilation on porcine hemodynamics and gas exchange during one-lung flooding

Abstract

BACKGROUND

Superimposed high-frequency jet ventilation (SHFJV) is suitable for respiratory motion reduction and essential for effective lung tumor ablation. Fluid filling of the target lung wing one-lung flooding (OLF) is necessary for therapeutic ultrasound applications. However, whether unilateral SHFJV allows adequate hemodynamics and gas exchange is unclear.

AIM

To compared SHFJV with pressure-controlled ventilation (PCV) during OLF by assessing hemodynamics and gas exchange in different animal positions.

METHODS

SHFJV or PCV was used alternatingly to ventilate the non-flooded lungs of the 12 anesthetized pigs during OLF. The animal positions were changed from left lateral position to supine position (SP) to right lateral position (RLP) every 30 min. In each position, ventilation was maintained for 15 min in both modalities. Hemodynamic variables and arterial blood gas levels were repeatedly measured.

RESULTS

Unilateral SHFJV led to lower carbon dioxide removal than PCV without abnormally elevated carbon dioxide levels. SHFJV slightly decreased oxygenation in SP and RLP compared with PCV; the lowest values of PaO₂ and PaO₂/FiO₂ ratio were found in SP [13.0; interquartile range (IQR): 12.6-5.6 and 32.5 (IQR: 31.5-38.9) kPa]. Conversely, during SHFJV, the shunt fraction was higher in all animal positions (highest in the RLP: 0.30).

CONCLUSION

In porcine model, unilateral SHFJV may provide adequate ventilation in different animal positions during OLF. Lower oxygenation and CO₂ removal rates compared to PCV did not lead to hypoxia or hypercapnia. SHFJV can be safely used for lung tumor ablation to minimize ventilation-induced lung motion.

Keywords: One-lung ventilation; Unilateral superimposed high-frequency jet ventilation; One-lung flooding

Core Tip: Lung cancer prognosis is among the most unfavourable of all cancers. Therefore, there is a need to improve local lung cancer therapy while avoiding surgery. One-lung flooding (OLF) involves unilateral lung filling with saline, which generates a suitable acoustic pathway for the transthoracic application of High-intensity focused ultrasound (HIFU) in the lung. Breathing and lung movement during HIFU procedures can result in incomplete tumor ablation or collateral damage. Superimposed high-frequency jet ventilation (SHFJV) can reduce respiratory motion. However, it is unclear whether unilateral SHFJV allows adequate haemodynamics and gas exchange. In this porcine model, unilateral SHFJV may provide adequate ventilation to animals in different positions during OLF. Lower oxygenation and carbon dioxide removal rates compared to pressure controlled ventilation did not lead to hypoxia or hypercapnia. SHFJV can safely minimise ventilation-induced lung motion during lung tumor ablation.