• J M Staalsø, T Edsen, B Romner, and N V Olsen.
• Department of Neuroscience and Pharmacology, Faculty of Health, University of Copenhagen, Copenhagen, Denmark.
• Br J Anaesth. 2013 Apr 1;110(4):577-85.

BackgroundTranscranial Doppler measurements of the middle cerebral artery flow velocity are widely used as an indicator of vasospasm after aneurysmal subarachnoid haemorrhage (SAH). We investigated inter- and intraoperator agreement in SAH patients and healthy volunteers using colour-coded transcranial Doppler (TCCD), with the secondary aim of describing prediction of angiographic vasospasm and mortality.MethodsSixty patients and 70 healthy controls were each examined in duplicate by alternating operators. A total of 939 measurements divided on 201 examination sets were conducted by four observers. The Bland-Altman limits of agreement (LoA) were calculated using a variance components analysis. Angiography was performed on clinical indication and survival recorded at 30 days.ResultsDifferences between measurements increased with increasing average, and therefore, we analysed log-transformed values. Thus, LoA are given as ratios between measurements. There were no systematic intra- or interobserver differences (bias). The intraobserver LoA was 0.62-1.61 in patients and 0.67-1.50 in controls. However, they were 0.55-1.82 in patients with angiographic vasospasm, whereas in patients without, they were 0.66-1.52. The interobserver LoA was 0.55-1.81 in patients and 0.65-1.55 in controls, while in patients with and without angiographic vasospasm, they were 0.45-2.22 and 0.60-1.67, respectively. Flow velocity measurements day 6-10 were positively associated with 30 day mortality risk (P=0.02, logistic regression).ConclusionsTCCD measurement variability is wider in patient measurements than in controls. This discrepancy can largely be explained by a higher degree of error in patients with angiographic vasospasm. Despite the considerable measurement variability in TCCD, values are predictive of outcome in SAH.

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