Previous work has assumed that left phrenic arterial blood flow (Q̇pa) reflects diaphragmatic blood flow. We have tested this assumption in four anesthetized mechanically ventilated dogs by measuring Q̇pa with a Doppler flow probe and regional diaphragmatic blood flow with radiolabeled microspheres. Flows were examined during control 1 (diaphragm at rest), pacing (phrenic pacing: rate 20/min, duty cycle 0.33), control 2, hypotension (rest with mean arterial pressure reduced by 45% of the control 1 value), and hypotension and pacing. As a percent of the control 1 value, Q̇pa was 511 ± 107% during pacing, 139 ± 12% during control 2, 40 ± 13% during hypotension, and finally 347 ± 31% during hypotension and pacing. Similarly, percent left hemidiaphragmatic blood flow (Q̇lh) was 362 ± 91% during pacing, 91 ± 10% during control 2, 14 ± 2% during hypotension, and finally 213 ± 50% during hypotension and pacing. The changes in flow to the left costal and crural diaphragm were similar to those recorded for Q̇lh. We conclude that Q̇pa correlates with total and regional diaphragmatic blood flow (r = 0.77 - 0.81, P < 0.001) under conditions of supramaximal phrenic nerve stimulation in which the metabolic demands of the region perfused by the phrenic artery are presumed to be similar to the metabolic demands of the rest of the diaphragm.
|Original language||English (US)|
|Number of pages||6|
|Journal||Journal of applied physiology|
|State||Published - Jan 1 1988|
ASJC Scopus subject areas
- Physiology (medical)