The Effect of Sigh Breaths on Volume Delivery During Simulated Neonatal High Frequency Jet Ventilation

Abstract

Background:

HFJV is used in tandem with a conventional ventilator and PEEP is adjusted to titrate mean airway pressure. Ventilator sigh breaths superimposed on HFJV to recruit alveoli and improve gas exchange. Studies in-vivo have shown a 2-3 fold increase lung injury/inflammation with sighs than without sighs (Musk, 2012, 2011). Clinicians may set PIPvent>PIPjet in order to provide chest rise with sigh breaths. We hypothesized that there would be no differences in pressure and volume delivery to a test lung between sigh/no sigh conditions during simulated HFJV.

Methods:

The Ingmar ASL 5000 was configured with restrictive and obstructive neonatal lung disorders. The Bunnell Life Pulse HFJV was connected to conventional ventilator with common HFJV settings for RDS:HFJV PIP:25, RR:420, PEEP: 8 (Sigh Rate:6, T_I :0.3s, Sigh PIP:27) and MAS: HFJV PIP:35, RR:300, PEEP: 14 (Sigh Rate: 6 Sigh, T_I :0.4s PIP:37). V_T and pressures (PIP, PEEP, MAP) were measured (n = 5) during simulated HFJV with/without sigh breaths.

Results:

When RDS and MAS lung models were supported with HFJV, volumes and pressures were greater with sigh breaths than without sigh breaths during HFJV (P < .05; see Figure).

Conclusions:

The major finding from this study was that application of sigh breaths during HFJV resulted in excessive V_T (∼15 mL/kg) and intrinsic PEEP levels (∼11 cm H₂O). These data corroborate findings from previous studies that show increased pulmonary injury/inflammation when applying sighs during HFJV. Based on these findings, we do not support using sigh breaths at any time during the course of HFJV. Instead, clinicians should adjust the ventilator PEEP during HFJV for optimization of end-expiratory lung volumes and gas exchange.