336 ASYMPTOMATIC ORTHOSTATIC HYPOTENSION AND RISK OF FALLS IN COMMUNITY-DWELLING OLDER PEOPLE

Background

Many older people with Orthostatic Hypotension (OH) may not report typical symptoms of dizziness, light-headedness, or unsteadiness. However, the relationships between OH and falls in the absence of typical symptoms are not yet established.

Methods

Continuous orthostatic BP was measured during active stand using a Finometer at Wave 1 of TILDA in participants aged≥70 years. OH, with and without dizziness, was defined as a sustained drop in systolic BP≥20 and/or diastolic BP≥10 mm Hg at 30, 60 and 90 seconds post-standing. The association between symptoms of dizziness and orthostatic BP was assessed with multi-level mixed-effects linear regression; logistic regression models assessed the longitudinal relationship between OH and falls at 6-year follow-up (Waves 2-5).

Results

Almost 11% (n=934; mean age: 75 years; 51% female) had OH, two-thirds of whom were asymptomatic. Dizziness was not associated with systolic BP drop at 30 (β=1.54; –1.27, 4.36; p=0.256), 60 (β=2.6; –0.19, 5.47; p =0.476) or 90 (β=2.02; –0.91, 4.95; p=0.176) seconds after standing in adjusted models. Asymptomatic OH was independently associated with unexplained falls (Odds Ratio: 2.01; 1.11, 3.65; p=0.022) but not explained falls (OR 0.93; 0.53, 1.62; p=0.797) during follow-up.

Conclusion

Two-thirds of older people with OH did not report typical symptoms of light-headedness. Dizziness or unsteadiness after standing did not correlate with the degree of orthostatic BP drop or recovery. Participants with asymptomatic OH had a significantly higher risk of unexplained falls during follow-up, and this has important clinical implications for the assessment of older people with falls.

127 ‘BONE HEALTH AND FRACTURE RISK ASSESSMENT IN COPD EXACERBATIONS DURING HOSPITALISATION- ROOM FOR IMPROVEMENT?’

Background

COPD increases the risk of osteoporosis and international guidelines recommend that such patients undergo fracture risk assessment, referral for densitometry and appropriate management. We aimed to identify if patients admitted to our hospital with COPD exacerbation underwent assessment and were prescribed bone protection medication.

Methods

All admissions with COPD exacerbation to an Irish level 2 hospital between July 2020 and July 2021 were identified. The discharge summaries were screened for information regarding the presence of fracture risk and bone health assessment. Discharge prescriptions were examined for calcium, vitamin d and anti-osteoporosis medications. Radiology reports were screened for fragility fractures.

Results

Between July 2020–2021, there were 3,840 presentations to the medical assessment unit. Forty-six patients were admitted with a diagnosis of COPD exacerbation, mean age 72 (56% female). Seventy eight percent were classified as having GOLD Stage D disease with 28% receiving long term oxygen therapy. Mean number of hospitalisations per year per patient was 1.91 ± 1.2. Forty-three percent had laboratory evidence of bone health assessment during admission. Only 50% of patients were discharged on vitamin d replacement; 22% on calcium supplementation and 4% on osteoporotic medications. Regarding previous fractures, 9% had evidence of fragility fracture described on radiology reports, this was not mentioned on any hospital discharge letter.

Conclusion

This study suggests that opportunities for bone health assessment and intervention may be under recognised in COPD patients. Ways to improve this may include proformas and visual aids to prompt assessment and documentation of bone health, further education to increase awareness and greater access to densitometry resources in the community. In conclusion, this study highlights that further attention to patients’ bone health assessment and commencement of appropriate treatment is warranted. Admission to hospital or clinic review for such patients provide important opportunities for intervention.

160 TIME TO BIN ‘NEXT OF KIN’?—JUNIOR DOCTORS DEMONSTRATE POOR UNDERSTANDING OF THE TERM IN IRELAND

Background

‘Next of kin’ (NOK) is a term widely used in the healthcare setting in Ireland to indicate an individual that can be contacted in the event of an emergency when a patient is in hospital. While it has its origins in Irish inheritance law, the term confers no legal or decision-making authority to any other individuals on behalf of a patient in hospital. However, anecdotally, the term is commonly misunderstood with a false belief among healthcare staff that consent should be sought from the NOK when a patient is unable to do so. In this study we sought to assess current understanding of the term among Irish non-consultant hospital doctors (NCHDs).

Methods

Data was collected via an online survey, completed by NCHDs across a number of medical and surgical disciplines to investigate their understanding of the term. Descriptive analysis of data was performed in Excel.

Results

118 NCHDs completed the survey. While 110 (93.2%) believed a NOK was an emergency contact, 53 (44.9%) believed they assisted in decision making; 58 (49.2%) thought they could provide medical information about the patient. Forty-four doctors (37.3%) believed a NOK was permitted to make medical decisions while 59 (50%) felt they could provide consent on behalf of an incapacitated patient. Sixty-three (53.4%) believed a NOK had legal entitlement to information over and above that of another family member or friend.

Conclusion

This study highlights several misconceptions surrounding the term ‘next of kin’ in the Irish healthcare setting, particularly around the area of decision-making authority and consent. The term is confusing and unhelpful and should not be used in healthcare. ‘Contact person’ or ‘emergency contact’ are appropriate alternatives. Further education to NCHDs around consent and maintenance of patient autonomy is necessary.

172 ‘NCHD’S UNDERSTANDING OF THE ‘DYING WITH DIGNITY BILL”

Background

The Dying with Dignity Bill is potential legislation that would permit terminally ill people to avail of medical assistance to die in certain circumstances. It would give a medical practitioner the legal right to provide assistance to a qualifying person to end their life, thus changing the medical landscape as we know it. This project aimed to assess current understanding in non-consultant hospital doctors (NCHDs) of the Dying with Dignity Bill.

Methods

An online survey was distributed to NCHD’s across a range of disciplines to ascertain current knowledge of the Dying with Dignity Bill. Descriptive analysis of data was conducted on Excel.

Results

The survey was completed by 80 NCHDs. Of respondents 67.5% (n = 54) of respondents had heard of the Bill and 32.5% (n = 26) of them knew what it was. The Bill had not been read by 88% (n = 71) of respondents. Fifty seven per cent (n = 46) did not understand what was entailed in the Bill. The majority agreed (61.3%; n = 49) that it would impact their work as a clinician. Some 70.1% (n = 56) agreed that legislation was needed in this area. The majority answered neutral (45%; n = 35) that their profession were consulted in the creation of the Bill. It is believed that the Bill will not require a vote however 48% (n = 37) believed it would. However, the majority (72.7%, n = 56) answered correctly that the Bill had not been enacted yet. This Bill does not define the length of a ‘terminal illness’ yet 36.8% (n = 28) believed it to be within six months. It also states that it is the practitioner’s role to decide when somebody is palliative and only 54.5% (n = 42) knew this.

Conclusion

The Dying with Dignity Bill is poorly understood by NCHDs, despite it potentially having an impact on the role of hospital doctors in Ireland. Discussion and involvement of NCHD’s in the potential formation of this Bill is crucial.

204 FRAILTY BUT NOT AGE IS ASSOCIATED WITH IMPAIRED ORTHOSTATIC CEREBRAL OXYGENATION

Background

The effects of age and frailty on cerebrovascular function are poorly understood. Here we investigate the hypotheses that aging, and frailty are accompanied by impaired regulation of cerebral oxygenation during standing in a patient population of older adults.

Methods

We recruited patients from a national Falls and Syncope service. All patients underwent an active stand test (5–10 min lying, 3 min standing) with continuous monitoring of blood pressure (BP) and heart rate. Tissue saturation index (TSI) was concurrently measured using near-infrared spectroscopy and its recovery measured at 30s after standing. Frailty was assessed as a comorbidity count using a 27-item questionnaire. Robust linear regression was used to investigate the association between TSI, age and frailty in a multivariate model with covariate adjustment, including the concurrent BP values. A p-value <0.05 was considered significant.

Results

304 patients (median(IQR): 71(14) years, 57% females) were recruited. Age was not associated with cerebral oxygenation after standing (β: −0.001 (−0.017 0.015), p = 0.899), even after stratification by sex (males: β: −0.010 (−0.045 0.024), p = 0.558, females: β: 0.000 (−0.017 0.018), p = 0.967). Frailty, was associated with a lower TSI at 30s after standing (β: −0.153 (−0.248–0.058), p = 0.002). After sex stratification, no associations with frailty were observed in males (β: −0.052 (−0.226 0.123), p = 0.557), while frailer females demonstrated a lower TSI at 30 seconds after standing (β: −0.179 (−0.294–0.063), p = 0.003) despite BP correction.

Conclusion

Our results suggest alternative mechanisms of cerebral oxygenation regulation independent of blood pressure (and presumably cerebral autoregulation) are involved in frailty related impairments of brain haemodynamics which are also independent of ageing. Such impairments represent novel biomarkers of frailty and represent potentially novel modifiable risk factors (independent of BP management) of hypoperfusion related disorders in clinical ageing.

239 IS ORTHOSTATIC HYPOTENSION ASSOCIATED WITH ALTERED CEREBRAL PERFUSION DURING ACTIVE STANDING?

Background

Orthostatic Hypotension (OH) is associated with poor health outcomes in later life including depression, cognitive impairment, frailty and falls. Whilst it is hypothesised that OH compromises cerebral autoregulation leading to hypoperfusion, this has not been robustly demonstrated to date. This study investigated the association between OH and cerebral perfusion during orthostasis using a non-invasive surrogate of cerebral perfusion, Near Infrared Spectroscopy (NIRS).

Methods

Four hundred and ninety one participants (58% female, median age 65, IQR 38–92) attending a falls and syncope service underwent measurement of beat-to-beat blood pressure (BP) by finometry and real-time frontal lobe perfusion (% TSI: Tissue Saturation Index) by NIRS during the active stand manoeuvre. We examined the association between OH and change in cerebral perfusion (delta TSI) using mixed-effects linear regression, with adjustment for important clinical covariates.

Results

Nearly two-fifths of the sample (189/491,38.5%) met criteria for OH occurring between 30 and 120 seconds after standing. Using mixed effects linear regression models, we observed a significant relationship between OH and TSI at the same timepoint (β −0.53, −0.59 to −0.46, p < 0.001) which persisted following adjustment for confounders including age, sex, baseline blood pressure, cerebrovascular and cardiovascular disease, depression/anxiety, diabetes, systolic blood pressure, antihypertensives, and antidepressants (β −0.51, −0.58 to −0.44, p < 0.001). Cerebral perfusion levels differed for those with OH compared to those without.

Conclusion

OH is independently associated with lower frontal lobe cerebral perfusion. This association may indicate disruption to dynamic cerebral autoregulation and explain the significant link between OH and poor health outcomes.

Frailty is associated with impaired cerebral oxygenation recovery during

 

Frailty is associated with impaired peripheral circulatory responses to standing in older adults. However, little is known about how frailty affects cerebrovascular function during such activities of daily living. Here we investigate the association between frailty and cerebral oxygenation during standing in a large clinical cohort of fallers and fainters.

Participants were recruited from a national Falls and Syncope unit and underwent an active stand test (5–10 minutes lying supine, 3 minutes standing) with concurrent monitoring of continuous blood pressure (BP) and heart rate (HR) and tissue saturation index (TSI) using near-infrared spectroscopy (NIRS). Frailty was measured using a count of deficits (27 morbidities). Robust linear regression was applied to study the association between features of dynamic cerebral oxygenation (changes from baseline at nadir, overshoot, 30s and steady state; and recovery rate) and frailty while correcting for covariates. A p-value <0.05 was considered significant.

Frailty was associated with deficits in TSI at 30s after standing (β: −0.165, CI: (−0.261, −0.069), p=0.005), as well as a lower diastolic BP at 30s (β: −1.346, CI: (−2.287, −0.405), p=0.032) and standing steady-state (β: −1.182, CI: (−2.038, −0.325), p=0.032). When stratified by gender, frailty was associated in women with a lower TSI at overshoot (β: −0.174, CI: (−0.312, −0.037), p=0.043) and 30s (β: −0.216 (−0.344, −0.089), p=0.010), and impaired DBP recovery at overshoot (β: −1.623, CI: (−2.865, −0.391), p=0.045) and attenuated HR response at 30s (β: −0.701, CI: (−1.246, −0.155), p=0.036). No associations were found in men.

Impaired cerebral oxygenation and BP responses to standing are associated with frailty in patients with falls and syncope, with stronger effects in women, suggesting that frailty may increase risk of hypoperfusion and consequent syncope, falls, and brain ageing. Our results demonstrate the clinical utility and feasibility of using NIRS in this context which can be used to further personalise patient management.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Irish Research Council Cerebral oxygenation and frailty

Cerebral perfusion responses to active standing are attenuated in patients with vasovagal syncope

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Irish Research Council (IRC): Government of Ireland Postgraduate Scholarship Programme 2018, Dublin, Ireland Fundació Universitària Agustí Pedro i Pons, Universitat de Barcelona, Barcelona, Spain

Background

Syncope is a transient loss of consciousness due to cerebral hypoperfusion. While traditionally peripheral haemodynamics are monitored during clinical assessment of syncope, relatively little is known about cerebrovascular haemodynamics during orthostasis in patients with syncope.

Purpose

Here we investigated whether young patients with syncope present an altered cerebral perfusion when compared to healthy controls. Given potential hyper-reactivity of the autonomic nervous system previously reported in these patients, we hypothesise that an overly active cerebral autoregulation will be present in patients with syncope.

Methods

Consecutive patients were prospectively recruited from a National Falls and Syncope Unit, and a convenience sample of young healthy community dwelling adults was recruited from a local university (16-30 years). Participants performed a 3 minute active stand test with continuous measurement of beat-to-beat peripheral haemodynamics (blood pressure (BP), heart rate (HR)) and changes in concentration of oxygenated Δ[O2Hb] and deoxygenated Δ[HHb] haemoglobin were derived from a near-infrared spectroscopy (NIRS) monitor. Baseline, steady state and other time domain features were derived for Δ[O2Hb] (nadir, overshoot, overshoot-to-nadir, overshoot-to-nadir recovery rate) and Δ[HHb] (peak, trough, peak-to-trough, peak-to-trough recovery rate) and multiple linear regression was used to compare differences between the two groups correcting for covariates (p < 0.05 significant).

Results

Patients (n = 40) were younger (20(5.5) vs 23(1) years, p = 0.003) than controls (n = 17) and were well matched in gender, weight, height, BMI and resting haemodynamics. Patients had a smaller Δ[O2Hb] overshoot-to-nadir difference (β: -0.749, CI:(-1.593 0.094), p = 0.08), a slower Δ[O2Hb] recovery rate (β: -0.186, CI:(-0.388 0.016), p = 0.071), and smaller Δ[HHb] peak-to-trough difference (β: -0.530, CI:( -0.921 0.138), p = 0.018) and slower Δ[HHb] recovery rate (β: -0.151, CI: (0.244 0.057), p = 0.008).

Conclusion

Patients with syncope had signs of an attenuated cerebral oxygenation response to an AS when compared to controls. We hypothesise that this is due to hyper-reactive cerebral autoregulation mechanism, which might be related to a hyper-sensitive autonomic system. Furthering our understanding of vasovagal syncope physiology can help inform future interventions and treatments. This study shows the clinical value of measuring cerebral perfusion using NIRS, an easy to use and readily applicable tool, in the assessment of syncope. Abstract Figure. Cerebral oxygenation upon standing

Do patients with syncope have a hyper-reactive autonomic nervous system?

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Irish Research Council (IRC): Government of Ireland Postgraduate Scholarship Programme 2018, Dublin, Ireland Fundació Universitària Agustí Pedro i Pons, Universitat de Barcelona, Barcelona, Spain.

Background

The origin of syncope, a transient loss of consciousness due to cerebral hypoperfusion, remains unclear. Recent studies suggest that a hypersensitive autonomic nervous system might be involved in the pathophysiology of vasovagal syncope (VVS).

Purpose

Here we test the hypothesis that patients with VVS have a hyper-reactive autonomic nervous system by investigating the peripheral haemodynamic responses during a standing (AS) test in a group of young VVS patients vs a control group.

Methods

A prospective sample of consecutive patients from a National Falls and Syncope Unit was recruited, and a convenience sample of young healthy community dwelling adults was recruited from a local university (16-30 years). Participants performed a 3 minute AS with continuous measurement of beat-to-beat blood pressure (BP), heart rate (HR), and cerebral oxygenation measured with near infrared spectroscopy. Baseline, steady-state and other time domain features were obtained for systolic BP (SBP) (i.e. nadir, overshoot, overshoot-to-nadir, overshoot-to-nadir recovery rate) and for HR (i.e. peak, trough, peak-to-trough, peak-to-trough recovery rate). Multiple linear regression was used to compare these features between patients and controls while correcting for covariates (p < 0.05 significant).

Results

Forty patients and 17 controls were included, the former group being younger ((20(5.5) vs 23(1) years, p = 0.003). During steady-state standing SBP was higher as compared to controls (β: 6.853, CI: (0.713 12.993), p = 0.029). Patient data trended toward lower steady-state HR (β: -5.262, CI:(-11.201 0.677), p = 0.081), together with a larger peak-to-trough difference (β: 7.212, CI:(1.329 -15.754), p = 0.096).

Conclusion

These results tend to support the hypothesis and previous literature suggesting the presence of autonomic hyper-reactivity in patients with syncope, presenting as an exaggerated peripheral circulatory response to standing. Understanding the pathophysiology of VVS can help us improve its assessment and develop better treatment pathways for these patients. Abstract Figure.

The cross-sectional association between diabetes and orthostatic hypotension in community-dwelling older people

AIMS

Orthostatic hypotension is a recognized complication of diabetes, but studies examining prevalence in diabetes are limited. The aim of this study was to ascertain the prevalence of orthostatic hypotension and the pattern of orthostatic BP response in a cohort of people with diabetes aged ≥ 50 years, embedded within the Irish Longitudinal Study of Ageing.

METHODS

Orthostatic hypotension was defined as a drop in systolic blood pressure (SBP) ≥ 20 mmHg or drop in diastolic blood pressure (DBP) ≥ 10 mmHg at 30 s after standing. Diabetes was defined by self-report but cross-checked against HbA_1c and medication records. Multilevel mixed effects linear regression models were used to compare orthostatic BP in people with and without diabetes.

RESULTS

Some 3222 people were included, 7% (213 of 3222) of whom had diabetes. Prevalence of orthostatic hypotension in the group with diabetes was 22% (46 of 213) vs. 13% in those without diabetes; χ² = 12.43; P < 0.001. Multilevel models demonstrated prolonged recovery of DBP in people with diabetes, with only 41% (87 of 213) returning to baseline by 60 s. Logistic regression models demonstrated that diabetes was associated with a significantly increased likelihood of orthostatic hypotension (odds ratio 1.84, 95% confidence interval 1.30-2.59; P = 0.001) and this remained robust after controlling for covariates.

CONCLUSION

Over one-fifth of older people with diabetes had orthostatic hypotension. Recovery of DBP is related to dynamic changes in total peripheral resistance and impairment of this baroreflex-mediated response may explain the higher prevalence in diabetes. Given the prognostic implications when co-existing with diabetes, orthostatic hypotension may represent a potentially modifiable risk factor for adverse outcomes in late-life diabetes.

Near-infrared spectroscopy in evaluating psychogenic pseudosyncope-a novel diagnostic approach

BACKGROUND

Psychogenic pseudosyncope (PPS), a conversion disorder and syncope mimic, accounts for a large proportion of 'unexplained syncope'. PPS is diagnosed by reproduction of patients' symptoms during head-up tilt (HUT). Electroencephalogram (EEG), a time consuming and resource intensive technology, is used during HUT to demonstrate absence of cerebral hypoperfusion during transient loss of consciousness (TLOC). Near-infrared spectroscopy (NIRS) is a simple, non-invasive technology for continuous monitoring of cerebral perfusion. We present a series of patients for whom PPS diagnosis was supported by NIRS during HUT.

METHODS

Eight consecutive patients with suspected PPS referred to a syncope unit underwent evaluation. During HUT, continuous beat-to-beat blood pressure (BP), heart rate (HR) and NIRS-derived tissue saturation index (TSI) were measured. BP, HR and TSI at baseline, time of first symptom, presyncope and apparent TLOC were measured. Patients were given feedback and followed for symptom recurrence.

RESULTS

Eight predominantly female patients (6/8, 75%) aged 31 years (16-54) were studied with (5/8, 63%) having comorbid psychiatric diagnoses, and (5/8, 63%) presenting with frequent episodes of prolonged TLOC with eyes closed (6/8, 75%). All patients experienced reproduction of typical events during HUT. Systolic BP (mmHg) increased from baseline (129.7 (interquartile range [IQR] 124.9-133.4)) at TLOC (153.0 (IQR 146.7-159.0)) (P-value = 0.012). HR (bpm) increased from baseline 78 (IQR 68.6-90.0) to 115.7 (IQR 93.5-127.9) (P-value = 0.012). TSI (%) remained stable throughout, 71.4 (IQR 67.5-72.9) at baseline vs. 71.0 (IQR 68.2-73.0) at TLOC (P-value = 0.484).

CONCLUSIONS

NIRS provides a non-invasive surrogate of cerebral perfusion during HUT. We propose HUT incorporating NIRS monitoring in the diagnostic algorithm for patients with suspected PPS.

75 Is Cerebral Autoregulation Altered in Ageing? A Review

Introduction

Cerebral autoregulation (CA) ensures constant cerebral blood flow (CBF) in the face of blood pressure (BP) disturbances. While CA impairment is often implicated in the aetiology of age-related disorders e.g. falls, syncope, and brain ageing, there is conflicting evidence on the effect of normal or healthy ageing on cerebral autoregulation. Here we present results of a review investigating the effect of ageing on CA.

Methods

A search was performed in Pubmed using the search terms “cerebral autoregulation” AND (“ageing” OR “age” OR “older” OR “elderly”). Studies were included if they were human studies in English assessing CA in healthy volunteers (free from disease) in which the effect of ageing on CAR was studied. Exclusion criteria included non-human studies, diseased cohorts and studies not measuring CA.

Results

26 studies (n=1326 total participants, age range 12-88) meeting the inclusion/exclusion criteria were identified. Significant heterogeneity was noted in applied methodologies with 88% of studies using static and 53% using dynamic protocols to measure CA. Transcranial Doppler (88%) and Near Infrared Spectroscopy (NIRS) (11%) were the most commonly used. Transfer function analysis (TFA) (38%), the Autoregulatory Index (ARI) (15%), and wavelet analysis (11%) were used to derive CA metric. The majority of studies suggested that CA is preserved (n=15) with ageing. However, a smaller number of studies (n=7) noted that CA is impaired or altered with ageing.

Conclusions

There is a paucity of literature examining the relationship between CA and chronological ageing, with 60 per cent of studies reviewed suggesting that CA is preserved. Current hypotheses suggest that preservation of CA with ageing serves as a ‘reserve’ to compensate for impairment of other systems. Future work should investigate the role of impaired CA as potential biomarker of biological ageing.

P5678Near-infrared spectroscopy (NIRS) in the evaluation of psychogenic pseudosyncope - Moving towards a simplified diagnostic pathway

Background

Psychogenic pseudosyncope (PPS) is a conversion disorder that often mimics syncope, is commonly referred to cardiology clinics and accounts for a large proportion of patients admitted with “unexplained syncope”. Unlike syncope, PPS is characterized by normal blood pressure (BP) and heart rate (HR) values at TLOC inferring the absence of cerebral hypoperfusion. The current gold standard for the diagnosis of PPS is the reproduction of patients' symptoms during a head-up tilt test (HUTT) with concurrent electroencephalogram (EEG) monitoring showing normal haemodynamic and brainwave measurements. However, EEG is time consuming, resource intensive and many syncope units lack ready access, thereby solely relying on absence of peripheral haemodynamic changes to diagnose PPS.

Purpose

Near-infrared spectroscopy (NIRS) is a non-invasive technology used for continuous monitoring of cerebral oxygenation. Measuring adequacy of tissue oxygenation is an appropriate surrogate for cerebral perfusion. In this study, we present a case series of patients for whom the diagnosis of PPS was confirmed by NIRS during TLOC. We propose use of NIRS in routine clinical assessment of suspected PPS.

Methods

We describe nine consecutive patients with suspected PPS referred to a dedicated syncope unit for investigation of recurrent unexplained syncope. All patients underwent evaluation in accordance with European Society of Cardiology guidelines including HUTT. Continuous beat-to-beat BP and HR measurements were recorded using finger plethysmography. In addition, continuous NIRS-derived tissue saturation index (TSI) - a measure of percentage oxygenation - was recorded using an optical sensor applied to the left lateral forehead to assess cerebral perfusion. Absolute values of BP, HR and TSI at baseline, time of first symptom onset, presyncope and apparent TLOC were recorded. The evaluation was diagnostic for PPS when apparent TLOC occurred in the absence of typical haemodynamic or cerebral perfusion changes.

Results

The median age was 35 years (range 14–54). Clinical features were consistent with those previously described in PPS literature - female preponderance, comorbid psychiatric diagnosis, frequent attack history, with prolonged TLOC and eyes closed during events. During HUTT, all patients experienced an apparent TLOC which they recognised as reproductive of typical events. BP and HR measurements increased significantly at time of TLOC. There was no significant change in TSI at any of the time points throughout HUTT. (Figure 1 shows averaged absolute values of systolic and diastolic BP, HR and TSI with median values represented by thickened lines.)

Figure 1. Measurements during HUTT

Conclusion

NIRS is readily available, easily accessible and provides an appropriate surrogate measure of cerebral perfusion during HUTT. We propose that HUTT incorporating concurrent NIRS monitoring will enhance diagnostic yield and patient management providing important biofeedback.