P. De Haan et al., Development of spinal cord ischemia after clamping of noncritical segmental arteries in the pig, ANN THORAC, 68(4), 1999, pp. 1278-1284
Citations number
24
Categorie Soggetti
Cardiovascular & Respiratory Systems","Medical Research Diagnosis & Treatment
Background. Blood flow to the thoracolumbar spinal cord is thought to be cr
itically dependent on the arteria radicularis magna. We investigated whethe
r spinal cord blood supply becomes dependent on other, noncritical, segment
al arteries if spinal cord perfusion pressure (SCPP) is decreased. The SCPP
is equal to the mean arterial pressure (MAP) minus the cerebrospinal fluid
(CSF) pressure (SCCP = MAP - CSF).
Methods. The thoracoabdominal aorta was exposed in 10 pigs. Functional inte
grity of spinal cord motor pathways was assessed with myogenic motor-evoked
potentials after transcranial electrical stimulation (tc-MEPs). Using this
technique, a group of segmental arteries not critical for spinal ford bloo
d supply was identified. Before, during, and after clamping of the noncriti
cal segmental arteries, spinal cord ischemia was produced by decreasing SCP
P by means of increasing CSF pressure, and the SCPP threshold at which tc-M
EPs showed evidence of spinal cord ischemia was determined. Ischemic SCPP t
hresholds, obtained during and after clamping of the noncritical segmental
arteries, were compared with the ischemic threshold obtained before clampin
g (control value).
Results. Before noncritical segmental arteries were clamped, ischemic tc-ME
P changes occurred when the SCPP was below 15 +/- 5 (SD) mm Hg. With a tota
l of 9 +/- 3 (SD) segmental arteries clamped, the ischemic SCPP threshold w
as 48 +/- 14 mm Hg (p < 0.01). After the release of all clamps, ischemia oc
curred at a SCPP of 15 +/- 5 (SD) mm Hg.
Conclusions. In this porcine experiment, clamping of originally noncritical
segmental arteries significantly reduced the tolerance of the spinal cord
to a decrease in SCPP. (C) 1999 by The Society of Thoracic Surgeons.