RT Journal Article
SR Electronic
T1 Mechanical ventilation induces a time-dependent reduction in diaphragmatic blood flow
JF European Respiratory Journal
JO Eur Respir J
FD European Respiratory Society
SP p5001
VO 38
IS Suppl 55
A1 Christian Bruells
A1 Robert Davis III
A1 John Stabely
A1 Bradley Behnke
YR 2011
UL http://erj.ersjournals.com/content/38/Suppl_55/p5001.abstract
AB Introduction: Continuous mandatory ventilation (CMV) induces atrophy of the diaphragm, contributing to ventilator induced diaphragmatic dysfunction (VIDD), which is significant after 6 h of CMV. However, the effects of prolonged CMV on diaphragmatic blood flow remain unknown. Therefore, we tested the hypothesis that long term CMV (6 h) will further decrease diaphragm perfusion versus that measured during acute CMV (30 min) and may contribute, in part, to VIDD due to reduced oxygen delivery.Methods: Blood flow to the diaphragm and other skeletal muscle was assessed (via the radioactive microsphere technique) during spontaneous breathing (SB) and after 30 min and 6 h of CMV in female Sprague-Dawley rats (n= 42). Blood pressure and heart rate were monitored continuously throughout the protocol.Results: In the midcostal portion of the diaphragm blood flow decreased by ∼ 32% from SB to 30 min CMV, with a further reduction in flow of ∼ 37% after 6 h CMV (i.e., SB 28.3±3.5 vs. CMV, 30 min 19.3±2.9; 6 h 8.8±0.6 ml/100 g/min; P<0.05). The other constituents of the diaphragm demonstrated a similar trend in perfusion over time. Blood flow to other hindlimb skeletal muscle did not decrease significantly at any time point.Discussion: Our study demonstrates, for the first time, that there is a time-dependent reduction in diaphragmatic perfusion during prolonged CMV. Further, a decrease in blood flow over the same time period was not observed in other skeletal muscles, even with matched oxidative capacities (e.g., red. portion of the gastrocnemius). Our data indicate that prolonged CMV elicits vascular dysfunction in the diaphragm which may contribute, in part, to the ongoing process of VIDD.