J. Weiswasser et al., PRESSURE-CYCLED VERSUS VOLUME-CYCLED VENTILATION IN LIQUID-VENTILATEDNEONATAL PIGLET LUNGS, Journal of pediatric surgery, 33(7), 1998, pp. 1158-1162
Background/Purpose: If the goal of partial liquid ventilation (PLV) wi
th perfluorocarbons in the management of respiratory failure is to imp
rove dynamic lung compliance (C-dyn) and pulmonary vascular resistance
(PVR) while sustaining O-2 delivery, the optimal ventilatory manageme
nt is unclear. The authors asked if volume-cycled or pressure-limited
ventilation had different effects on PVR, cardiac index (CI), and C-dy
n in uninjured and injured neonatal piglet lungs. Methods: Anesthetize
d piglets (6 to 8 kg) were ventilated after tracheostomy. C-dyn was me
asured by in-line Fleisch pneumotach/PC data acquisition terminal. The
rmodilution instrumentation allowed determination of both CI and PVR.
Volume-control or pressure-limited ventilation was established in unin
jured or injured (surfactant deficiency induced by saline ravage at 18
mL/kg) animals. After a stable 30-minute baseline, animals were assig
ned randomly to one of four groups: group I (n = 9), uninjured animals
plus volume-cycled ventilation (intermittent mandatory ventilation [I
MV], 10 bpm; tidal volume [TV], 15 mL/kg, positive end-expiratory pres
sure [PEEP], 5 cm H2O; FIO2, 1.0; and PLV for 150 minutes); group II (
n = 9), uninjured animals plus pressure-limited ventilation (IMV, 10 b
pm; peak inspiratory pressure (PIP), 25 cm H2O, PEEP, 5 cm H2O, FIO2 1
.0; and PLV for 150 minutes); group III (n = 7), injured animals plus
volume-cycled ventilation (IMV, 10 bpm; TV, 15 mL/kg; PEEP, 5 cm H2O;
FIO2, 1.0 for 30 minutes, followed by saline injury for 30 minutes, fo
llowed by PLV rescue for 120 minutes); group IV (n = 7), injured anima
ls plus pressure-limited ventilation (IMV, 10 bpm; PIP, 25 cm H2O; PEE
P, 5 cm H2O; FIO2, 1.0 for 30 minutes, followed by saline injury, and
PLV rescue). Comparison within and between groups was accomplished by
repeated measures analysis of variance (ANOVA) with Tukey correction.
Results: There was no significant difference between volume-cycled or
pressure-limited ventilation in healthy lungs; however, in the setting
of lung injury, dynamic compliance was 1.44 +/- 0.15 after 180 minute
s in the volume-cycled group and 0.91 +/- 0.10 in the pressure-limited
group after the same interval (mL/cm H2O - kg +/- SEM). Similarly, PV
R was 100 +/- 6 in the volume-cycled group and 145 +/- 12 in the press
ure-limited group after 180 minutes of lung injury (mm Hg/L/ kg . min
+/- SEM). Cardiac index declined significantly in all groups independe
nt of ventilatory mode. Conclusions: These results suggest that in the
setting of lung injury, C-dyn and PVR improved significantly when vol
ume-cycled, compared with pressure-limited ventilation was used. Altho
ugh no difference existed between ventilatory modes in healthy lungs,
pressure-limited ventilation, when combined with PLV in injured lungs,
had adverse effects on lung compliance and pulmonary vascular resista
nce. Volume-cycled ventilation may optimize the ability of perfluoroca
rbon to recruit collapsed or atelectatic lung regions. J Pediatr Surg
33:1158-1162. Copyright (C) 7998 by W.B. Saunders Company.