Blood flow to respiratory muscles and major organs during inspiratory flow resistive loads.
To determine whether diaphragmatic fatigue in the intact animal subjected to loaded breathing is associated with a decrease in diaphragmatic blood flow, seven unanesthetized sheep were subjected to severe inspiratory flow resistive (IFR) loads that led to a decrease in transdiaphragmatic pressure (Pdi) and a rise in arterial PCO2 (PaCO2). Blood flow to the diaphragm, other respiratory muscles, limb muscles, and major organs was measured using the radionuclide-labeled microsphere method. With these loads blood flow increased to the diaphragm (621 +/- 242%) and all the other inspiratory and expiratory diaphragm (621 +/- 242%) and all the other inspiratory and expiratory muscles; there was no statistically significant change in blood flow to these muscles at the time when Pdi decreased and PaCO2 rose. Blood flow also increased to the heart (103 +/- 34%), brain (212 +/- 39%), and adrenals (76 +/- 9%), whereas pancreatic flow decreased (-66 +/- 14%). Limb muscle blood flow remained unchanged. We conclude that in unanesthetized sheep subjected to IFR loads 1) we did not demonstrate a decrease in respiratory muscle blood flow associated with diaphragmatic fatigue and ventilatory failure, and 2) there is a redistribution of blood flow among major organs.
Pang
L M
LM
Department of Anesthesia, Columbia University College of Physicians and Surgeons, New York, New York 10032.
Kim
Y J
YJ
Bazzy
A R
AR
D000818:Animals; D001784:Blood Gas Analysis; D001831:Body Temperature / Q000502:physiology; D002245:Carbon Dioxide / Q000097:blood; D002302:Cardiac Output / Q000502:physiology; D003964:Diaphragm / Q000098:blood supply; D006863:Hydrogen-Ion Concentration; D008863:Microspheres; D009132:Muscles / Q000098:blood supply; D012039:Regional Blood Flow / Q000502:physiology; D012119:Respiration / Q000502:physiology*; D012132:Respiratory Muscles / Q000098:blood supply*; D012756:Sheep
D002245:Carbon Dioxide