EurekaMag.com logo
+ Site Statistics
References:
53,623,987
Abstracts:
29,492,080
+ Search Articles
+ Subscribe to Site Feeds
EurekaMag Most Shared ContentMost Shared
EurekaMag PDF Full Text ContentPDF Full Text
+ PDF Full Text
Request PDF Full TextRequest PDF Full Text
+ Follow Us
Follow on FacebookFollow on Facebook
Follow on TwitterFollow on Twitter
Follow on LinkedInFollow on LinkedIn

+ Translate

RBC volume deficiency in patients with excessive orthostatic decrease in cerebral blood flow velocity



RBC volume deficiency in patients with excessive orthostatic decrease in cerebral blood flow velocity



Journal of the Chinese Medical Association 77(4): 174-178



Orthostatic intolerance (OI) is common but heterogeneous. There is a subgroup of OI patients who have excessive decrease in cerebral blood flow velocity (CBFV) of bilateral middle cerebral arteries (MCAs) during head-up tilt without systemic blood pressure change. This study evaluated the role of blood volume reduction in such patients. Patients with idiopathic OI who had excessive orthostatic decrease (>20% of the supine level) in mean CBFV of bilateral MCAs and who also received blood volume determination were collected. The chromium (⁵¹Cr) dilution method was used for red blood cell (RBC) volume determination in these patients. The blood volume was expressed as a percentage of the expected volume. These patients were further divided into two groups, those with postural tachycardia syndrome (POTS group) and those without (non-POTS group). The data of RBC volume were compared between the two groups. Besides, we used multivariate linear regression to evaluate the factors that predict RBC volume. Twenty-five patients (13 females, median age = 28 years) were enrolled in this study. Nine of these patients had POTS (5 females, median age = 26 years) and 16 did not (8 females, median age = 29.5 years). Compared with the expected volume, the RBC volume was significantly reduced in all patients (median = 82% of the expected volume). Moreover, the RBC volume was significantly lower in the POTS group than that in the non-POTS group (78% vs. 85% of the expected volume, p = 0.013). The orthostatic decrease of MCA flow velocity was 28.3% in the POTS group and 32.5% in the non-POTS group (p = 0.140). The orthostatic pulsatility index increment was 15.4% in the POTS group and 20.5% in the non-POTS group (p = 0.438). Moreover, basic demography and hemoglobin levels were not different between the two groups. After multivariate linear regression (dependent variables including age, sex, body surface, and groups), only the presence of POTS significantly predicted the RBC volume (p = 0.006). The results of our study indicated that low RBC volume may play an important role in the pathophysiology of OI in this group of patients. Moreover, its role seems even more relevant in patients with POTS than in those without. Further studies for mechanistic evaluation are needed in the future.

(PDF emailed within 0-6 h: $19.90)

Accession: 055333605

Download citation: RISBibTeXText

PMID: 24612999

DOI: 10.1016/j.jcma.2014.01.005



Related references

Exercise plus volume loading prevents orthostatic intolerance but not reduction in cerebral blood flow velocity after bed rest. American Journal of Physiology. Heart and Circulatory Physiology 302(2): H489-H497, 2012

Cerebral blood flow velocity and cranial fluid volume decrease during +Gz acceleration. Journal of Gravitational Physiology 4(3): 31-34, 2001

The effect of ephedrine on cerebral blood flow and middle cerebral artery velocity in patients orthostatic hypotension. Journal of Neurology Neurosurgery & Psychiatry 51(10): 1359, 1988

Orthostatic changes of cerebral blood flow velocity in patients with autonomic dysfunction. Journal of the Neurological Sciences 104(1): 32-38, 1991

Orthostatic hypotension and cerebral blood flow velocity in the rehabilitation of stroke patients. International Journal of Rehabilitation Research. Internationale Zeitschrift für Rehabilitationsforschung. Revue Internationale de Recherches de Readaptation 29(4): 339-342, 2006

Hemodialysis causes severe orthostatic reduction in cerebral blood flow velocity in diabetic patients. American Journal of Kidney Diseases 34(6): 1096-1104, 1999

Cerebral blood flow velocity declines before arterial pressure in patients with orthostatic vasovagal presyncope. Journal of the American College of Cardiology 39(6): 1039-1045, March 20, 2002

Excessive oscillations in cerebral blood flow associated with orthostatic intolerance. Neurology 50(4 SUPPL 4): A240, April, 1998

The influence of hyperoxia on regional cerebral blood flow (rCBF), regional cerebral blood volume (rCBV) and cerebral blood flow velocity in the middle cerebral artery (CBFVMCA) in human volunteers. Magnetic Resonance Imaging 20(7): 535-541, 2002

Preservation of middle cerebral blood flow velocity during head-up tilt with L-DOPS, a precursor of norepinephrine , in patients with orthostatic hypotension. Journal of the American Society of Nephrology 13(Program and Abstracts Issue): 210A, September, 2002

Modeling Cerebral Blood Flow Velocity During Orthostatic Stress. Annals of Biomedical Engineering 43(8): 1748-1758, 2016

Doppler-assessed cerebral blood flow velocity in the neonate as estimator of global cerebral blood volume flow measured using phase-contrast magnetic resonance angiography. Neonatology 103(1): 21-26, 2013

The effect of orthostatic hypotension on cerebral blood flow and middle cerebral artery velocity in autonomic failure, with observations on the action of ephedrine. Journal of Neurology, Neurosurgery, and Psychiatry 52(8): 962-966, 1989

Cerebral blood flow velocity during orthostatic stress with ganglionic blockade. Medicine & Science in Sports & Exercise 32(5 Suppl ): S66, 2000

Orthostatic variation in cerebral blood flow velocity in dysautonomic diabetics. Diabetologia 38(SUPPL 1): A239, 1995