Background: Inadequate intraoperative cerebral perfusion and increased
serum anticholinergic activity (SAA) have been suggested as possible causes
of postoperative cognitive dysfunction (POCD).
Methods: 53 patients aged >65 yrs undergoing elective major surgical procedures
under standardized general anaesthesia. Cerebral perfusion was monitored
with transcranial Doppler and near-infrared spectroscopy. Mx, an index of
cerebral autoregulation was calculated based on the correlation of spontaneous
changes inmean arterial blood pressure (MAP) and cerebral blood flow velocity.
Cognitive function was measured preoperatively and 7 days postoperatively
using the CERAD-Neuropsychological Battery. A postoperative decline >1
z-score in at least 2 cognitive variables was defined as POCD. SAA was
measured preoperatively and 7 days postoperatively (data available for 38
patients). CRP was measured at the same time points and 2 days postoperatively.
Results: Age was 75_7 yrs (mean_SD). 23 patients (43%) developed POCD.
There were no statistical significant differences between patients with POCD
and without POCD in age (77_7 vs 73_6 yrs), MAP (74_12 vs 78_11
mmHg), cerebral tissue oxygenation indices (67_6 vs 69_4 %) SAA
preoperatively (1.74_1.52 vs 1.74_1.21) and 7 days postoperatively
(1.90_1.63 vs 1.84_1.39) and CRP preoperatively (32_72 vs 7_9), 2 days
postoperatively (176_129 vs 111_69) and 7days postoperatively (53_43 vs
48_25). Patients with POCD had less efficient autoregulation than patients
without POCD (Mx 0.55_0.15 vs 0.45_0.20, p = 0.046). However, the percentage
of patients with clearly impaired autoregulation (ie, Mx>0.5) was
statistically not different between groups (with POCD: 65%; without POCD:
38%; p = 0.06) but there seems to be a trend.
Conclusions: Our data on the association between cerebral perfusion and
POCD in elderly patients are inconclusive and more patients need to be
investigated. In this small group of patients SAA seems not to be associated
with POCD.