Am. J. Respir. Crit. Care Med., Volume 159, Number 1, January 1999, 49-54

Expiratory Phase Tracheal Gas Insufflation and Pressure Control in Sheep with Permissive Hypercapnia

HIDEAKI IMANAKA, MAX KIRMSE, HARALD MANG, DEAN HESS, and ROBERT M. KACMAREK

Respiratory Care Department Laboratory and the Department of Anesthesia, Massachusetts General Hospital, and Harvard Medical School, Boston, Massachusetts

Tracheal gas insufflation (TGI) has been shown to be a useful adjunct to mechanical ventilation, decreasing Pa_CO2 during permissive hypercapnia. While TGI can be used either with pressure (PCV) or volume-controlled ventilation and continuously or only during the expiratory phase (Ex-TGI), there are no controlled studies evaluating the effects of Ex-TGI with PCV in acute lung injury when the direction of the insufflated flow or the inspiratory:expiratory (I:E) ratio are varied. We evaluated the effect that Ex-TGI with PCV would have on CO₂ removal during both direct and reverse insufflated flow direction with varied I:E ratios when peak airway pressure, total positive end-expiratory pressure (PEEP), and tidal volume (VT) were kept constant. In addition we examined the effect that insufflation flow directed toward the mouth (reverse flow) would have on the generation of PEEP compared with flow directed toward the carina (direct flow). After saline lavage, nine sheep were ventilated with PCV to a baseline Pa_CO2 of 80 mm Hg. Ex-TGI (10 L/min) was then randomly applied in the reverse and direct direction with I:E set at 1:2 or 2:1. During 1:2 I:E Pa_CO2 decreased from 78 ± 4 mm Hg to 60 ± 7 mm Hg (23.5 ± 8.9%) with direct flow and to 64 ± 5 mm Hg (18.5 ± 5.5%) with reverse flow (p < 0.05), whereas during 2:1 I:E Pa_CO2 decreased from 80 ± 4 mm Hg to 69 ± 8 mm Hg (13.7 ± 9.2%) with direct flow and to 66 ± 4 mm Hg (17.2 ± 4.4%) with reverse flow (p < 0.05). Greater PEEP was developed with direct flow (2.8 cm H₂O I:E 1:2 and 4.0 cm H₂O I:E 2:1) than with reverse flow (0.9 cm H₂O I:E 1:2 and 0.4 cm H₂O I:E 2:1), p < 0.05. There was no difference in the Pa_CO2 change between I:E with reverse flow, but the Pa_CO2 decrease was greater (p < 0.05) during 1:2 versus 2:1 I:E with direct flow. CO₂ removal during PCV and Ex-TGI is more consistent with reverse flow than with direct flow and PEEP level is less affected by TGI with reverse flow than with direct flow.

This article has been cited by other articles:

				G. Zhu, T. H. Shaffer, and M. R. Wolfson Continuous tracheal gas insufflation during partial liquid ventilation in juvenile rabbits with acute lung injury J Appl Physiol, April 1, 2004; 96(4): 1415 - 1424. [Abstract] [Full Text] [PDF]

				C. S. Carter, J. R. Hotchkiss, A. B. Adams, M. K. Stone, and J. J. Marini Distal projection of insufflated gas during tracheal gas insufflation J Appl Physiol, May 1, 2002; 92(5): 1843 - 1850. [Abstract] [Full Text] [PDF]

				R. G. Brower, L. B. Ware, Y. Berthiaume, and M. A. Matthay Treatment of ARDS Chest, October 1, 2001; 120(4): 1347 - 1367. [Abstract] [Full Text] [PDF]

				G. DASSIEU, L. BROCHARD, M. BENANI, S. AVENEL, and C. DANAN Continuous Tracheal Gas Insufflation in Preterm Infants with Hyaline Membrane Disease . A Prospective Randomized Trial Am. J. Respir. Crit. Care Med., September 1, 2000; 162(3): 826 - 831. [Abstract] [Full Text]

				N. ROSSI, G. MUSCH, F. SANGALLI, M. VERWEIJ, N. PATRONITI, R. FUMAGALLI, and A. PESENTI Reverse-Thrust Ventilation in Hypercapnic Patients with Acute Respiratory Distress Syndrome . Acute Physiological Effects Am. J. Respir. Crit. Care Med., August 1, 2000; 162(2): 363 - 368. [Abstract] [Full Text] [PDF]

				M. KIRMSE, Y. FUJINO, J. HROMI, H. MANG, D. HESS, and R. M. KACMAREK Pressure-release Tracheal Gas Insufflation Reduces Airway Pressures in Lung-injured Sheep Maintaining Eucapnia Am. J. Respir. Crit. Care Med., November 1, 1999; 160(5): 1462 - 1467. [Abstract] [Full Text]