Predictive value of tidal volume and peak inspiratory pressure in normal frequency jet ventilation

Normal frequency jet ventilation (NFJV) is commonly used during rigid bronchoscopy; however, airway opening does not reliably measure or predict tidal volume (V_T) or peak inspiratory pressure (PIP). This study aimed to investigate the comprehensive effects on V_T and PIP concerning key variables, including driving pressure (DP_pipeline), frequency (F_jet), needle inner diameter (ID_needle), and lung dynamic compliance (C_dyn). Three jet needles (N₁, N₂, and N₃) with different internal diameters (1.2-1.9 mm) were used to deliver jet ventilation via a rigid bronchoscope at DPs of 0.6-1.6 bar and frequencies of 10-60 min⁻¹. Airway pressure (Paw) was measured near the tracheal prominence of the simulated lung. Expiratory gas flow was diverted into a dedicated collection chamber fitted with a solenoid valve over a one-minute period, and the collected volume was measured as minute volume (MV). ①. Statistical analysis of the two lung models revealed consistent findings: both V_T and PIP values in N₂ and N₃ demonstrated statistically significant differences compared to N₁ (P < 0.05). Additionally, significant differences in the V_T and PIP values were observed between N₂ and N₃ (P < 0.05). ②. Multiple linear regression analyses indicated that DP_pipeline, F_jet, and ID_needle had statistically significant effects on V_T and PIP (P < 0.05). Conversely, C_dyn significantly affected V_T (P < 0.05) but did not have a significant impact on PIP (P > 0.05). The primary variables exerting a significant influence on V_T and PIP were DP_pipeline, F_jet, and ID_needle. Furthermore, C_dyn significantly affected V_T but not PIP. V_T and PIP can be accurately predicted using regression equations.