Diaphragmatic pressures: transvenous vs. direct phrenic nerve stimulation.
Diaphragmatic force, determined by stimulating the phrenic nerve while simultaneously measuring the pressures in a closed respiratory system, was assessed in five anesthetized dogs over a 5-h period to evaluate the inherent variability of this technique. Transdiaphragmatic pressure (Pdi) was measured at functional residual capacity during stimulation (120 Hz, 0.2-ms duration) of one phrenic nerve by either direct phrenic nerve stimulation (DPNS) or transvenous phrenic nerve stimulation (TPNS). An analysis of variance showed no significant (P greater than 0.50) change during the 5-h period. There was a significant correlation (r = 0.94, P less than 0.001) between Pdi obtained by TPNS and that obtained by DPNS. It is concluded that either DPNS or TPNS can be used to evaluate diaphragmatic strength over a 5-h period and that TPNS can be used in lieu of DPNS.
D000818:Animals; D002404:Catheterization; D003964:Diaphragm / Q000502:physiology*; D004285:Dogs; D004558:Electric Stimulation / Q000379:methods*; D004566:Electrodes; D008297:Male; D010791:Phrenic Nerve / Q000502:physiology*; D010827:Physiology / Q000295:instrumentation; D011312:Pressure; D014132:Trachea / Q000502:physiology; D014680:Veins