Effects of controlled and pressure support mechanical ventilation on rat diaphragm muscle

purpose: the objective of this study was to analyze the effects of pressure controlled ventilation mode (pcv-c) and psv mode in diaphragm muscle of rats. methods: wistar rats (n=18) were randomly assigned to the control group or to receive 6 hours of pcv and psv. after this period, animals were euthanized and their diaphragms were excised, frozen in liquid nitrogen and stored in at -80o c for further histomorphometric analysis. results: results showed a 15% decrease in cross-sectional area of muscle fibers on the pcv-c group when compared to the control group (p<0.001) and by 10% when compared to the psv group (p<0.05). minor diameter was decreased in pcv-c group by 9% when compared with the control group (p<0.001) and by 6% when compared to the psv group (p<0.05). when myonuclear area was analyzed, a 16% decrease was observed in the pcv-c group when compared to the psv group (p<0.05). no significant difference between the groups was observed in myonuclear perimeter (p>0.05). conclusion: short-term controlled mechanical ventilation seems to lead to muscular atrophy in diaphragm fibers. the psv mode may attenuate the effects of vidd.