[Hypotension after turning to the prone position]

Hypotension after positioning is sometimes seen especially in patients with cervical spinal lesion operated on under prone position. Patients with spinal lesion and those with brain lesion are compared in the frequency of hypotension after positioning to prone. Sixty-one cases operated on with prone position were studied. Ages ranged from 40 to 82 (mean 61) years and ASA grade was 1 or 2 in each case. Cervical laminoplasty (group C) or craniotomy (group B) are performed in 40 and 21 patients, respectively. Ephedrine was administrated when the systolic blood pressure decreased under 80 mmHg and the frequency of ephedrine use was compared. There were no differences in age and sex distribution between group C and B. The induction doses of propofol and fentanyl in group B were larger than those of group C, but ephedrine use in group C was more frequent than in group B. In T2-weighted image of the cervical cord, high signal intensity areas were depicted in cases with hypotension. The sympathetic flow descends in the medial part in the lateral funiculus. Damage of this pathway would cause autonomic dysfunction in patients with cervical spinal lesion and strict monitoring is necessary during positioning to prone.