TITLE:
Effects of three controlled mechanical ventilation modes on rat lung hydrogen peroxide and apoptosis during hemorrhagic shock
AUTHORS:
Amanda R. Thimmesch, Qiuhua Shen, Richard L. Clancy, Janet D. Pierce
KEYWORDS:
Trauma; Animal Model; Lung Injury; Reactive Oxygen Species; Programmed Cell Death
JOURNAL NAME:
Open Journal of Molecular and Integrative Physiology,
Vol.3 No.1,
February
22,
2013
ABSTRACT: Hemorrhagic shock causes a reduction in oxygen
supply to tissues leading to increased reactive oxygen species resulting in
lung injury. Often mechanical ventilation is required as supportive treatment;
however, ventilation can also induce lung injury and apoptosis. The purpose of
this study was to examine the effects of three modes of controlled mechanical
ventilation: volume control, pressure control, and pressure regulated volume
control on lung injury as measured by hydrogen peroxide and apoptosis during
hemorrhagic shock. Male Sprague-Dawley rats were randomized to the three
controlled mechanical ventilation groups. Hemorrhagic shock was elicited by
removing approximately 40% of the blood volume over 30 minutes. The rats were
treated with one of three modes of mechanical ventilation with 40% oxygen for
60 minutes. The lungs were removed and measured for hydrogen peroxide and
apoptosis based on nuclear differential dye uptake. There were no significant
differences in hemodynamics, arterial blood values, peak inspiratory pressures,
tidal volume, respiratory rates, and intrathoracic pressures across three
groups. However, lung hydrogen peroxide production and apoptosis were
significantly increased in volume control and pressure control, compared to
pressure-regulated volume control. In this study, early signs of ventilator
induced lung injury were not detected using commonly employed clinical measurements.
However, when examining lung cellular injury (hydrogen peroxide and apoptosis),
we were able to measure significant lung damage in volume control and pressure
control, but not pressure-regulated volume control. Thus, our results suggest
that pressure-regulated volume control is the preferable mode of mechanical
ventilation during hemorrhagic shock.