R Giuliani, L Mascia, F Recchia, A Caracciolo, T Fiore and VM Ranieri
Istituto di Anestesiologia e Rianimazione, Universita di Bari, Italy.

Synchronized intermittent mandatory ventilation (SIMV) intermixes assisted and spontaneous breaths. Its ability as a weaning technique has been questioned on the basis that patients show little adaptation to ventilator assistance. We studied inspiratory effort and patient- ventilator interaction at different levels (SIMV, 100, 50, and 0%) of flow-triggered SIMV versus pressure-triggered SIMV in patients during the weaning period. The two triggering systems were evaluated during constant flow and constant pressure mandatory SIMV breaths. Inspiratory effort was estimated as the esophageal pressure time product (PTP) per breath (PTP/b) and per minute (PTP/min). The PTP/b and PTP/min of both mandatory and spontaneous breaths were significantly lower during flow triggering than during pressure triggering SIMV, irrespective of the ventilatory mode. During pressure-triggered SIMV PTP/b and PTP/min were identical for mandatory and spontaneous breaths, whereas during flow- triggered SIMV PTP/b and PTP/min were significantly lower for mandatory than for spontaneous breaths. This difference was greatest when flow triggering and constant pressure ventilation were associated. These data show that flow triggering reduces inspiratory effort during both mandatory and spontaneous SIMV breaths and obtains a better patient- ventilator interaction.

This article has been cited by other articles:

				E. Kondili, G. Prinianakis, and D. Georgopoulos Patient-ventilator interaction Br. J. Anaesth., July 1, 2003; 91(1): 106 - 119. [Full Text] [PDF]

				B. Schonhofer and S. Sortor-Leger Equipment needs for noninvasive mechanical ventilation Eur. Respir. J., October 1, 2002; 20(4): 1029 - 1036. [Abstract] [Full Text] [PDF]

				ATS/ERS Statement on Respiratory Muscle Testing Am. J. Respir. Crit. Care Med., August 15, 2002; 166(4): 518 - 624. [Full Text] [PDF]

				M. J. TOBIN, A. JUBRAN, and F. LAGHI Patient-Ventilator Interaction Am. J. Respir. Crit. Care Med., April 1, 2001; 163(5): 1059 - 1063. [Full Text]

				International Consensus Conferences in Intensive Care Medicine: Noninvasive Positive Pressure Ventilation in Acute Respiratory Failure . Organized Jointly by the American Thoracic Society, the European Respiratory Society, the European Society of Intensive Care Medicine, and the Societe de Reanimation de Langue Francaise, and approved by the ATS Board of Directors, December 2000 Am. J. Respir. Crit. Care Med., January 1, 2001; 163(1): 283 - 291. [Full Text]

				A. Jubran Advances in Respiratory Monitoring During Mechanical Ventilation Chest, November 1, 1999; 116(5): 1416 - 1425. [Abstract] [Full Text] [PDF]

				G. FOTI, M. CEREDA, G. BANFI, P. PELOSI, R. FUMAGALLI, and A. PESENTI End-Inspiratory Airway Occlusion . A Method To Assess the Pressure Developed by Inspiratory Muscles in Patients with Acute Lung Injury Undergoing Pressure Support Am. J. Respir. Crit. Care Med., October 1, 1997; 156(4): 1210 - 1216. [Abstract] [Full Text] [PDF]

				P. ASLANIAN, S. E. ATROUS, D. ISABEY, E. VALENTE, D. CORSI, A. HARF, F. LEMAIRE, and L. BROCHARD Effects of Flow Triggering on Breathing Effort During Partial Ventilatory Support Am. J. Respir. Crit. Care Med., January 1, 1997; 157(1): 135 - 143. [Abstract] [Full Text]