The Science Journal of the American Association for Respiratory Care

2005 OPEN FORUM Abstracts

PATHOPHYSIOLOGICAL EFFECTS OF HIGH FREQUENCY PERCUSSIVE VENTILATION AND CONVENTIONAL MECHANICAL VENTILATION IN AN ANIMAL MODEL WITH OLEIC ACID-INDUCED LUNG INJURY.

Adel Bougatef1 MD, PhD, Daniel De Wolf2 MD, PhD, Guido Van Nooten2 MD, PhD, Luc Foubert3 MD, PhD. 1NICU, Academic Hospital, Free University Brussels; 2Department of Paediatric Cardiology and Cardiosurgery, Ghent University Hospital; 3Department of Anaesthesia and Intensive Care, OLV Hospital Aalst; Belgium.

Introduction: Gas exchange and hemodynamics were investigated during high frequency percussive ventilation (HFPV) and conventional mechanical ventilation (CMV) in pigs with oleic-acid provoked lung injury (ALI).

Method: Sixteen pigs weighing 20.4±1.4 kg were employed, after animal preparation, baseline values of hemodynamic and ventilatory parameters were obtained following a 30-min stabilization period, after which lung injury was induced by intravenous injection of oleic acid over a period of 20 min. Thereafter, the animals were randomly assigned either CMV (group A) or HFPV (group B) at a FIO2 of 1.0, a PEEP of 4 cm H2O, a respiratory rate of 20 cycles/min, with an inspiratory time of 33% (CMV) and a high frequency rate of 10 Hz (HFPV), peak Paw was adjusted to achieve normocapnia (PaCO2 = 35 to 45 mm Hg) under guidance of a continuous blood gas monitoring. The ventilation mode was switched every hour for a total investigative period of 4 hours.

Results: PaO2 and consequently PaO2/FIO2 were significantly higher during each HFPV intervention than CMV (174.6±81.7 mm Hg vs 79.5±16.6 mm Hg in group A, and 188.7±47.3 mm Hg vs 69.6±19.9 mm Hg in group B) (p< 0.05). The pH was higher and the PaCO2 was lower during HFPV compared to CMV. In both groups, HFPV intervention resulted in a significant higher cardiac output (CO) and stroke volume (SV), as well as lower pulmonary vascular resistance (PVR) compared to CMV (p< 0.05), as summarized in the table below. Under all conditions, mean Paw was significantly lower during HFPV than CMV (11.1±1.1 cm H2O vs 16.3±2.4 cm H2O) (p< 0.05).

Group A Baseline ALI CMV 1 HFPV 1 CMV 2 HFPV 2
   90 min 150 min 210 min 270 min 330 min
MAP (mmHg) 81.5 ± 17.1 69.1 ± 14.2 64.7 ± 9.7 73.6 ± 14.4* 48.7 ± 5.6* 70.1 ± 12.9§
PVR (dyn.s.cm-5) 205 ± 60* 597 ± 165 730 ± 184* 479 ± 108 743 ± 313 479 ± 166§
SV (ml) 42.1 ± 7.1* 27.1 ± 8.9 22.2 ± 4.3* 32.8 ± 8.5 21.5 ± 4.0* 31.7 ± 8.6
CO (l/min) 4.4 ± 0.9 3.5 ± 0.8 3.0 ± 0.4* 4.1 ± 0.8 2.8 ± 0.2* 3.8 ± 0.9


Group B Baseline ALI HFPV 1 CMV 1 HFPV 2 CMV 2
   90 min 150 min 210 min 270 min 330 min
MAP (mmHg) 69.4 ± 7.3 64.2 ± 15.7 65.6 ± 12.8† 56.2 ± 13.1* 63.2 ± 13.8§ 47.5 ± 9.7*
PVR (dyn.s.cm-5) 153 ± 31* 507 ± 132 393 ± 81 549 ± 80 363 ± 126 599 ± 129
SV (ml) 49.7 ± 6.4* 34.8 ± 9.8 42.8 ± 7.0 31.8 ± 5.2 41.6 ± 7.6§ 26.9 ± 2.6
CO (l/min) 4.4 ± 0.5 3.9 ± 0.6 4.6 ± 0.7 3.7 ± 0.2 4.4 ± 0.4 3.3 ± 0.4*

* p < 0.05 vs ALI , † p < 0.05 HFPV1 vs CMV1, § p < 0.05 HFPV2 vs CMV2

Conclusion : The main understandings revealed in this study is that the application of HFPV improves oxygenation and ventilation without adverse hemodynamic effects in animal lung models with oleic acid induced respiratory insufficiency. This trend was confirmed when HFPV was applied immediately after ALI induction, or during post HFPV transitioning to CMV.

You are here: RCJournal.com » Past OPEN FORUM Abstracts » 2005 Abstracts » PATHOPHYSIOLOGICAL EFFECTS OF HIGH FREQUENCY PERCUSSIVE VENTILATION AND CONVENTIONAL MECHANICAL VENTILATION IN AN ANIMAL MODEL WITH OLEIC ACID-INDUCED LUNG INJURY.