Aim: Intraoperative electroencephalography, somato-sensory evoked potentials and transcranial Doppler have been proposed to replace carotid artery stump pressure measurement (CASP) as the test of choice in the evaluation of cerebral tolerance during temporary carotid occlusion. CASP is a simple, inexpensive test that does not require an additional specialist in the operating room. Herein, we attempt to demonstrate that CASP is a reliable test that does not need to be replaced by more sophisticated and expensive techniques.
Methods: Over the last 6 years, 1 135 consecutive carotid endarterectomies (CEA) were performed under general anesthesia at our institution. There were 592 males and 429 female patients with an age range of 39 to 95 years (mean 72 +/- 9 years). Hypertension, diabetes, smoking, coronary artery disease and chronic renal insufficiency were present in 71%, 39%, 36%, 32% and 26%, respectively. Internal carotid artery (ICA) stenosis ? 70% was confirmed by duplex scanning in 92% of the cases. The remaining 8% of cases had 50% to 69% ICA stenosis in neurologically symptomatic patients. Asymptomatic patients accounted for 75% of the cases. Contralateral ICA occlusion was observed in 57 cases (5%). Indwelling shunts were used when CASP was < 45 mmHg. Carotid patches were used in 233 cases. Completion duplex scanning was performed in all cases. CASP was measured by inserting a 23-gauge needle into the common carotid artery (CCA) after clamping the ICA to avert possible embolization during needle insertion. Once the tip of the needle was confirmed intraluminally by pressure measurement and triphasic waveform tracing, the CCA and the external carotid artery were clamped. After a flat line tracing was depicted on the monitor, ICA clamp was released and CASP was recorded.
Results: CASP was < 45 mmHg in 233 cases (21%) (Group I) and > or = 45 mmHg in 902 cases (79%) (Group II). The mean CASP in presence of contralateral ICA occlusions was 40 +/- 15 mmHg while it was 65 +/- 27 mmHg for patent contralateral ICAs (P < 0.0001). The overall 30-day stroke rate was 1% (1 135 cases). It was 3% (7/233) for group I and 0.5% (4/902) for group II (P < 0.01). In patients with postoperative strokes CASP ranged from 23 to 44 mmHg (mean 33 +/- 8) in group I (shunted) and it varied from 59 to 116 mmHg (mean 99 +/- 28) in group II (non-shunted) with P < 0.001. The causes of stroke in group I were hyperperfusion (2), partial ICA thrombosis (2), embolization (2) and worsening of acute stroke (1). In group II there were 2 cases of embolization and 2 of ICA thrombosis. No patient had a stroke caused by decreased intraoperative global cerebral perfusion. The overall 30-day mortality rate was 0.5%. The overall combined stroke/death rate was 1.5%.
Conclusion: CASP > or = 45 mmHg was a reliable predictor of adequate cerebral perfusion during 1,135 consecutive CEAs performed under general anesthesia. The percentage of indwelling shunts utilized in this series was not significantly different from the ones using more expensive and sophisticated techniques.