Isoflurane versus sodium nitroprusside for the control of proximal hypertension during thoracic aortic cross-clamping: effects on spinal cord ischemia.
OBJECTIVE
This study was designed to compare the effects of isoflurane and nitroprusside on spinal cord ischemia when they are used to control proximal hypertension during thoracic aortic cross-clamping (TACC).


METHODS
Prospective, randomized, blinded experimental study.


METHODS
Laboratory and animal research facility.


METHODS
Adult mongrel dogs.


METHODS
Two groups of eight dogs had TACC for 45 minutes. Proximal aortic, distal aortic, and cerebrospinal pressure was calculated as the distal mean pressure minus the CSF pressure. Group 1 received nitroprusside and group 2 received isoflurane to control proximal hypertension during cross-clamping. The dogs were neurologically evaluated 24 and 48 hours later by an observer blinded as to the study group. Spinal cord segments were obtained for histopathologic examination.


RESULTS
Distal perfusion pressure and spinal cord perfusion pressure were significantly higher in the isoflurane group (p < .005). At 24 hours, seven of eight dogs in group 1 had severe neurologic injury (ie, paraplegia), with the eight having mild neurologic injury. This is in contrast to group 2, where 6 of 8 dogs had either minimal or no injury, one had mild injury, and one had severe injury. Similar results were observed at 48 hours (p < .005).


CONCLUSIONS
Isoflurane, when used to control proximal hypertension during TACC, produces a higher spinal cord perfusion pressure and is associated with a lower incidence of neurologic injury than nitroprusside in this canine model.
Department of Anesthesiology, Long Island Jewish Medical Center, New Hyde Park, NY 11042, USA.
J I
JI
Simpson
T R
TR
Eide
G A
GA
Schiff
J F
JF
Clagnaz
Z
Z
Zisbrod
S B
SB
Newman
I
I
Hossain
D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology* / Q000627:therapeutic use; D001013:Aorta, Thoracic / Q000601:surgery*; D003250:Constriction; D004285:Dogs; D006439:Hemodynamics / Q000187:drug effects; D006973:Hypertension / Q000188:drug therapy*; D007511:Ischemia / Q000188:drug therapy* / Q000473:pathology; D007530:Isoflurane / Q000494:pharmacology* / Q000627:therapeutic use; D009599:Nitroprusside / Q000494:pharmacology* / Q000627:therapeutic use; D010264:Paraplegia / Q000517:prevention & control; D011446:Prospective Studies; D011897:Random Allocation; D013116:Spinal Cord / Q000098:blood supply* / Q000473:pathology
D000959:Antihypertensive Agents; D009599:Nitroprusside; D007530:Isoflurane