Moderate induced hypotension provides satisfactory operating conditions in maxillofacial surgery

Patients scheduled for maxillofacial surgery were randomly assigned to receive isoflurane (n = 22) or nitroglycerin (n = 18) in order to induce hypotension. Surgeons, blinded for the actual level of blood pressure and the technique used for inducing hypotension, were asked to rate operating conditions on a scale from 1 to 5. Systolic arterial pressure (SAP) and mean arterial pressure (MAP) were reduced by 26% for both groups. Although blood pressure levels showed little variation throughout the induced hypotension period, scores of 2 to 5 were given significantly more often at incision and at 30 min compared to the following measuring points (P < 0.01). In total, the surgical field was rated significantly more often with a score of 1 and 2 than with a score of 3 to 5 (P<0.01). A relation between score and SAP and/or MAP could not be found. There was also no relation between scores and the technique used for hypotension. Our data suggest that, with the exception of the first half hour of surgery, on average a SAP of 89 mmHg and a MAP of 65 mmHg were sufficient to produce satisfactory operating conditions.