Delirium is a common condition with poorly understood pathophysiology. Various theories have been proposed including that delirious patients have reduced cerebral blood flow. We hypothesised that ...patients with delirium could have abnormal autonomic nervous system function, as assessed by tilt table testing, which would explain the alteration in blood flow.
A prospective cohort study of medical inpatients aged 65 years and older was undertaken. Delirium was assessed using DRS-R98 and DSM-IV criteria. Beat-to-beat blood pressure (BP) was recorded during tilt testing. Differences in BP changes between the two groups (those with delirium and those without) were explored. The association between severity of delirium and magnitude of BP changes was also examined.
64 participants were recruited during hospitalisation. 29 completed follow-up Head-Up Tilt testing. The mean age of participants was 80.8 years (SD 6.2 years). The control group (n = 12) had a median decrease in systolic BP of 17.5 mmHg (IQR 20.75). The delirium group (n = 17) had a median decrease in systolic BP of 1 mmHg (IQR 38.5), p = 0.04. As delirium severity scores increased, systolic BP change during tilting also increased (rs = 0.42, p = 0.03).
Participants in the delirium group showed different BP responses to tilt test which may represent abnormal sympathetic response. This would be consistent with other features of delirium such as treatment response to centrally acting alpha-2 blockers.
Equity of access to research for older, frail and delirious cohorts is essential but feasibility and acceptability needs to be optimised and factored into study design.
•Recent delirium is associated with abnormal blood pressure response to head up tilt.•Pathophysiology of delirium may relate to sympathetic over-activity.•Difficulties with retention of frail patients should be factored into study design.
Abstract
Background
Delirium is common among unwell older adults. Despite this the pathophysiology remains poorly understood. We hypothesised that autonomic dysfunction may be associated with the ...development of delirium.
Methods
35 participants completed a case-control study. Delirium was assessed using DSM-IV and DRS-R98. Autonomic function was assessed with Head-Up Tilt testing (HUT), baroreflex sensitivity (BRS) testing using Baroreflex Effectiveness Index (BEI), 24-hour blood pressure variability (BPV), nocturnal blood pressure dipping status and 24-hour heart rate variability (HRV). A subgroup analysis of those without pre-existing cognitive impairment (CI) was completed.
Results
During tilting the delirium group (DG) had a median decrease of 1mmHg (IQR 38.5) in systolic blood pressure (SBP) compared to a median decrease of 17.5mmHg (IQR 20.75) in the control group (CG) (p=0.04). Increased delirium severity correlated with a reduction in the decrease in SBP (rs= -0.42, p=0.03).
In those without CI, BRS testing during HUT showed that increases in blood pressure were not followed by an appropriate reduction in heart rate with a mean BEI of 36.87% (SD 22.26) in the DG and 56.03% (SD 23.04) in the CG (p=0.05).
Nocturnal dipping differed during subgroup analysis. 58.3% (7) of DG were reverse dippers, 33.3% (4) were non-dippers and 8.3% (1) had a normal dipping pattern. In CG 57.1% (4) were non-dippers, 14.3% (1) had a normal dipping pattern and 28.6% (2) were extreme dippers (p=0.01).
BPV was measured by average real variability (ARV). In those without CI mean ARV was 13.81 (SD 5.98) in the CG and 9.69 (SD 2.75) in the DG (p=0.05).
No difference was detected in HRV.
Conclusion
We identified differences in autonomic function between the DG and CG. This is the first study to look at several components of autonomic function in delirium and thus can provide insights into physiological abnormalities present during, or contributing to delirium.
101Mass and the Dangers of Syncope Costello, Maria; Egan, Aisling; Leahy, Aoife ...
Age and ageing,
09/2018, Letnik:
47, Številka:
suppl_5
Journal Article
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