Neuropediatrics 2006; 210 - P126
DOI: 10.1055/s-2006-946481

Partial liquid ventilation distends small airways in a similar way as gas ventilation: a study of pulmonary stretch receptor activity during different pressure waveforms

E Rieger-Fackeldey 1, 2, R Sindelar 1, A Jonzon 1, A Schulze 2, G Sedin 1
  • 1Departement of Women's and Children's Health, Section for Pediatrics, Uppsala University, Uppsala, S
  • 2Department of Gynecology and Obstetrics, Division of Neonatology, Ludwig-Maximilian University, Munich, D

Objective: We have shown that squarewave pressure waveform strongly inhibits spontaneous inspiratory activity in cats during pressure controlled A/C ventilation (Ehrhardt et al, Crit Care Med, 2001). In studies of PSR activity during ventilation with gas (GV) and during partial liquid ventilation (PLV) no extensive stretching of the lungs was observed during PLV (Rieger-Fackeldey et al, Biol Neonat, 2005). To study the effects of different inspiratory pressure waveforms on pulmonary stretch receptor (PSR) activity during intermittent mandatory ventilation with gas (GV) and with partial liquid (PLV) in young cats with healthy lungs.

Methods: In 10 young cats (4.4 0.4 months, 2.3 0.3kg; mean SD) PSR instantaneous impulse frequency (PSR fimp) was recorded from single fibres in the vagal nerve during GV and during PLV with perfluorocarbon (30 mL/kg) with squarewave (squ) and sinusoidal (sin) inspiratory pressure waveform at increasing positive inspiratory pressures (PIP; 1.2, 1.8, 2.2 and 2.7 kPa), and at a PEEP of 0.5 kPa. Results: Peak and mean PSR fimp increased with higher PIPs and tidal volumes during both, PLV and GV. At the lowest PIP of 1.2 kPa, peak and mean PSR fimp was lower during PLV than during GV, both with squ and sin inspiratory pressure wave forms (p<0.01 in all instances). Time to peak PSR fimp was shorter with squ than with sin at all pressures during GV and PLV (p<0.005 at all settings). Differences in arterial blood gases between squ and sin were only observed at PIPs 1.2 and 1.8 kPa during PLV, but not during GV (p<0.047). Conclusions: A normal inflation and deflation of the small airways, as detected by PSR activity, seems to be maintained during PLV, when exposed to two different pressure waveforms, implying that the physiomechanical properties of the alveoli at the fluid-fluid interface (PLV) is similar to that at the gas-fluid interface (GV).