Intracranial Pressure Waveforms are More Closely Related to Central Aortic than Radial Pressure Waveforms: Implications for Pathophysiology and Therapy
In patients with subarachnoid haemorrhage, pulsatile intracranial pressure (ICP) is more strongly associated with adverse events than mean ICP. Furthermore, patients with idiopathic normal-pressure hydrocephalus (iNPH), and pulsatile ICP of 5 mmHg or more, gain more benefit from cerebrospinal fluid (CSF) shunting than those whose pulsatile ICP is lower than 5 mmHg.
Our study aims to investigate the morphological relationship between ICP pulsations, aortic pressure pulsations and radial artery pulsations. Central aortic pulse pressure has been known to be the best predictor of adverse cardiac events, whereas radial artery pulse pressure is generally measured and displayed in intensive care environments.
We studied 10 patients with iNPH, and their ICP and aortic and radial pressures were digitised, ensemble-averaged and compared in the time and frequency domains. The ICP wave contour was quite different to the radial pressure waveform. By contrast, the ICP waveform was similar to the aortic pressure wave contour. The ICP amplitude averaged <10 % of aortic pulse pressure. In the frequency domain, the relative amplitude of the first three harmonics was similar for the ICP and aortic pressure. Hence, monitoring central aortic pressure through derivation from the radial pressure wave is superior to measurement of radial pressure alone.
KeywordsIntracerebral pressure waveform Central aortic pressure waveform Pressure waveform analysis
Conflict of Interest Statement
Dr O’Rourke is a founding director of AtCor Medical P/L, manufacturer of the pulse wave analysis system, SphygmoCor, and of Aortic Wrap P/L, the developer of methods to reduce aortic stiffness, and is consultant to Novartis and Merck. Other authors have nothing to disclose.
- 1.Mancia G, Fagard R, Narkiewicz K, Redon J, Zanchetti A, Bohm M, Christiaens T, Cifkova R, DeBacker G, Dominiczak A, Galderisi M, Grobbee DE, Jaarsma T, Kirchhof P, Kjeldsen SE, Laurent S, Manolis AJ, Nilsson PM, Ruilope LM, Schmieder RE, Sirnes PA, Sleight P, Viigimaa M, Waeber B, Zannad F (2013) 2013 ESH/ESC Guidelines for the management of arterial hypertension: the Task Force for the management of arterial hypertension of the European Society of Hypertension (ESH) and of the European Society of Cardiology (ESC). J Hypertens 31:1281–357CrossRefPubMedGoogle Scholar
- 2.Eide PK, Sorteberg A, Bentsen G, Marthinsen PB, Stubhaug A, Sorteberg W (2012) Pressure-derived versus pressure wave amplitude-derived indices of cerebrovascular pressure reactivity in relation to early clinical state and 12-month outcome following aneurysmal subarachnoid hemorrhage. J Neurosurg 116:961–71CrossRefPubMedGoogle Scholar
- 3.Nichols WW, O’Rourke MF, Vlachopoulos C (2011) McDonald’s blood flow in arteries, 6th edn. Arnold Hodder, LondonGoogle Scholar
- 6.Hirata K, O’Rourke MF, Momomura S (2007) Favourable effect of sublingual nitrate on carotid flow and pressure augmentation index. J Clin Hypertens 9(Suppl A):A29Google Scholar
- 7.Hirata K, O’Rourke MF, Momomura S (2008) Flow augmentation index as a major risk factor for silent lacunar infarction. J Hypertens 26(Suppl 1):S395Google Scholar