HOBOE (Head-of-Bed Optimization of Elevation) Study: association of higher angle with reduced cerebral blood flow velocity in acute ischemic stroke

Variations in Cortical Oxygenation by Near-Infrared Spectroscopy According to Head Position after Acute Stroke: The Preliminary Findings of an Observational Study

Background: After ischemic stroke, there is no general consensus on the optimal position for the head of patients in the acute phase. This observational study aimed to measure the variations in cortical oxygenation using noninvasive functional near-infrared spectroscopy (fNIRS) at different degrees of head positioning on a bed. Methods: Consecutive ischemic stroke patients aged 18 years or older with anterior circulation ischemic stroke within 48 h of symptom onset who could safely assume different positions on a bed were included. A 48-channel fNIRS system was placed in the bilateral sensorimotor cortex. Then, the bed of each patient was moved into four consecutive positions: (1) seated (90° angle between the head and bed surface); (2) lying at 30°; (3) seated again (90°); and (4) lying flat (0°). Each position was maintained for 90 s; the test was conducted 48 h after stroke onset and after 5 ± 1 days. The variations in oxygenated hemoglobin in the global brain surface and for each hemisphere were recorded and compared. Results: Twenty-one patients were included (males, n = 11; age, 79 ± 9 years; ASPECTS, 8 ± 2). When evaluating the affected side, the median oxygenation was significantly greater in the lying-flat (0°) and 30° positions than in the 90° position (p < 0.001 for both comparisons). No significant differences between the supine position and the 30° position were found, although oxygenation was slightly lower in the 30° position than in the supine position (p = 0.063). No differences were observed when comparing recanalized and nonrecanalized patients separately or according to stroke severity. The evaluation conducted 5 days after the stroke confirmed the previous data, with a significant difference in oxygenation at 0° and 30° compared to 90°. Conclusions: This preliminary study suggested that there are no substantial differences in brain oxygenation between the lying-flat head position and the 30° laying position.

Evaluation of Cerebral Perfusion Pressure, Cerebral Blood Flow, and Cerebral Oxygenation at Different Head of Bed Positions Using Transcranial Doppler and Near-Infrared Spectroscopy in Postoperative Neurosurgical Patients

OBJECTIVES

Nursing postoperative neurosurgical patients with head of bed (HOB) elevation beyond 30° might be desired at times to prevent pulmonary complications. Due to the paucity of studies determining the effect of HOB beyond 30° on cerebral perfusion pressure (CPP), cerebral blood flow (CBF), and regional cerebral oxygenation (rSO2), this study was designed.

METHODS

A total of 40 patients following elective neurosurgery for supratentorial tumors were studied in the neurosurgical intensive care unit three hours following admission. They were assessed for CBF velocities of middle cerebral arteries on either side using transcranial color Doppler (TCCD), rSO2 using near-infrared spectroscopy (NIRS), and mean arterial pressure measured at tragus level at various HOB positions. The estimated cerebral perfusion pressure (CPPe) was calculated from TCCD parameters, and the estimated intracranial pressure (ICPe) was then derived. Their variations at different HOB positions were noted.

RESULTS

TCCD parameters such as peak systolic velocity (PSV) and mean flow velocity (MFV) did not significantly vary upon elevating HOB from 0° to 30° but reduced significantly when HOB was further elevated to 60° (p < 0.05). ICPe reduced significantly with a change of HOB positions from 0° to 60° (p < 0.001), and a significant reduction in CPPe was noticed when HOB was elevated to 60° (67.2 ± 10.1 mmHg vs. 74.7 ± 11.2 mmHg at 0°). However, none of these HOB positions affected rSO2 values.

CONCLUSION

Postoperative nursing with positions up to 60° HOB can be tried in indicated patients following elective neurosurgery when complemented with CBF velocity and rSO2 monitoring and in whom CPP-guided therapy is not preferred.

The effect of head-down tilt in experimental acute ischemic stroke

BACKGROUND

Collateral therapeutics exert a promising protective effect on the outcome of acute ischemic stroke. Cerebral blood flow (CBF) may be modulated by different head positioning. The current study aimed to determine the effect of head-down tilt (HDT) on stroke in a rodent model.

METHODS

The model of middle cerebral artery occlusion and reperfusion (MCAO/R) was used in this study. Neurological deficit scoring, 2,3,5-triphenyltetrazolium chloride staining, brain water content, perivascular aquaporin protein-4 (AQP4) localization, pericyte marker platelet-derived growth factor receptor β (PDGFRβ), and CBF velocity were evaluated at 24 h after MCAO/R and HDT treatment.

RESULTS

In the rat model of MCAO/R, brain infarct volume and neurological deficit score were significantly alleviated in the -30° and -60° groups compared to those in the lying flat (0°) group. Compared with the 0° group, an increase in CBF velocity was detected in the -30° group through two-photon microscopy imaging at 24 h after MCAO/R. Compared with the SHAM group, a decrease in PDGFRβ was observed in both the MCAO/R and HDT treatment (-30°) groups. The integrated optical density of PDGFRβ was found to be higher in the HDT treatment (-30°) group than in the MCAO/R group. An impairment in perivascular AQP4 polarity and an increase in brain water content were observed after MCAO/R, which were not exacerbated by HDT treatment (-30°).

CONCLUSIONS

Our findings suggest that HDT treatment at certain degrees may exert a neuroprotective effect after MCAO/R through improving CBF velocity and the protection of pericytes.

International beliefs and head positioning practices in patients with spontaneous hyperacute intracerebral hemorrhage

Background

Prior to the conduct of the Head Position in Stroke Trial (HeadPoST), an international survey (n = 128) revealed equipoise for selection of head position in acute ischemic stroke.

Objectives

We aimed to determine whether equipoise exists for head position in spontaneous hyperacute intracerebral hemorrhage (ICH) patients following HeadPoST.

Design

This is an international, web-distributed survey focused on head positioning in hyperacute ICH patients.

Methods

A survey was constructed to examine clinicians' beliefs and practices associated with head positioning of hyperacute ICH patients. Survey items were developed with content experts, piloted, and then refined before distributing through stroke listservs, social media, and purposive snowball sampling. Data were analyzed using descriptive statistics and χ² test.

Results

We received 181 responses representing 13 countries on four continents: 38% advanced practice providers, 32% bedside nurses, and 30% physicians; overall, participants had median 7 [interquartile range (IQR) = 3-12] years stroke experience with a median of 100 (IQR = 37.5-200) ICH admissions managed annually. Participants disagreed that HeadPoST provided 'definitive evidence' for head position in ICH and agreed that their 'written admission orders include 30-degree head positioning', with 54% citing hospital policies for this head position in hyperacute ICH. Participants were unsure whether head positioning alone could influence ICH longitudinal outcomes. Use of serial proximal clinical and technology measures during the head positioning intervention were identified by 82% as the most appropriate endpoints for future ICH head positioning trials.

Conclusion

Interdisciplinary providers remain unconvinced by HeadPoST results that head position does not matter in hyperacute ICH. Future trials examining the proximal effects of head positioning on clinical stability in hyperacute ICH are warranted.

Assessment of dynamic cerebral autoregulation in near-infrared spectroscopy using short channels: A feasibility study in acute ischemic stroke patients

Introduction

In acute ischemic stroke, progressive impairment of cerebral autoregulation (CA) is frequent and associated with unfavorable outcomes. Easy assessment of cerebral blood flow and CA in stroke units bedside tools like near-infrared spectroscopy (NIRS) might improve early detection of CA deterioration. This study aimed to assess dynamic CA with multichannel CW-NIRS in acute ischemic stroke (AIS) patients compared to agematched healthy controls.

Methods

CA reaction was amplified by changes in head of bed position. Long- and short channels were used to monitor systemic artery pressure- and intracranial oscillations simultaneously. Gain and phase shift in spontaneous low- and very low-frequency oscillations (LFO, VLFO) of blood pressure were assessed.

Results

A total of 54 participants, 27 with AIS and 27 age-matched controls were included. Gain was significantly lower in the AIS group in the LFO range (i) when the upper body was steadily elevated to 30. and (ii) after its abrupt elevation to 30°. No other differences were found between groups.

Discussion

This study demonstrates the feasibility of NIRS short channels to measure CA in AIS patients in one single instrument. A lower gain in AIS might indicate decreased CA activity in this pilot study, but further studies investigating the role of NIRS short channels in AIS are needed.

Effect of head-down tilt on clinical outcome and cerebral perfusion in ischemic stroke patients: A case series

Background

The effect of head position on stroke is not clear. The current study aimed to observe the effect of head-down tilt on acute ischemic stroke (AIS) patients with large vessel occlusion.

Methods

We observed the influence of head-down tilt position on clinical outcomes, myocardial enzymogram and N-terminal pro b-type Natriuretic Peptide in 4 AIS patients who suffered early neurological deterioration (END). Cerebral perfusion imaging was performed in 3 patients using arterial spin labeling.

Results

In series of AIS patients with END, head down tilt (-20°) prevented further neurological deterioration and improved clinical outcomes. An increase in cerebral blood flow was observed by arterial spin labeling after head down tilt treatment. No obvious adverse events occurred.

Conclusion

The case series suggest that head-down tilt may improve clinical outcome in AIS patients through increasing the cerebral perfusion with no obvious adverse events. The finding needs to be confirmed in future clinical trials.

The Sky's the Limit: Expanding Nursing's Contribution to Acute Stroke Science

Stroke is the number one cause of preventable disability in adults in the United States. Significant advances have occurred in medications and technology supporting rapid stroke diagnosis and treatment during the past 30 years, along with blurring of the lines of what traditionally constituted nursing or medical research. Ischemic stroke is a disease of vascular insufficiency that mirrors myocardial infarction more than any other neurologic diagnosis. My primary program of research is focused on exploration of methods to improve intracranial blood flow in patients with hyperacute ischemic stroke who have viable, yet vulnerable, brain tissue to prevent worsening or enable improvement of stroke symptoms. I am also examining augmentation of recombinant tissue plasminogen activator treatment and stimulation of both arteriogenesis and angiogenesis with external counter-pulsation in patients with intracranial atherosclerosis. My secondary program of research focuses on methods to improve stroke systems of care, including improvement of advance practice providers' contributions to acute stroke care, use of innovative mobile stroke units, and improvement of quality core measure processes. Lessons learned along the way are highlighted, along with the value of interdisciplinary "team science" to build knowledge and enhance the care of highly vulnerable patients with acute stroke.

The effect of head positioning on cerebral hemodynamics: Experiences in mild ischemic stroke

BACKGROUND AND PURPOSE

It is generally agreed that optimal head positioning is an important consideration in acute stroke management regime. However, there is limited literature investigating the effect of head positioning changes on cerebrovascular physiology in acute ischemic stroke (AIS). We aim to assess cerebral autoregulation (CA) and associated hemodynamic responses during gradual head positioning (GHP) changes, between AIS and controls.

METHODS

Cerebral blood flow velocity (CBFV, transcranial Doppler), blood pressure (BP, Finometer) and end-tidal CO₂ (capnography) were recorded between lying flat (0°) and sitting up (30°) head position, in 16 controls (8 women, mean age 57 ± 16 yrs) and 15 AIS patients (7 women, 69 ± 8 yrs). AIS patients carried out three visits at 13.3 ± 6.9 h, 4.8 ± 3.2 days and 93.9 ± 11.5 days from symptom onset, respectively.

RESULTS

AIS patients were significantly hypertensive (p = 0.005), hypocapnic (p < 0.001), and had lower CBFV (p = 0.02) compared to controls, in both head positions. When comparing 5-min FLAT to SIT head position, reductions in BP (both AIS and controls, p < 0.001) and CBFV (controls only: dominant hemisphere p = 0.001 and non-dominant hemisphere p = 0.05) were demonstrated. Of note, a reduction in autoregulation index was observed in AIS, after 5-min SIT head positioning, at all 3 visits (p = 0.018).

CONCLUSION

Key hemodynamic changes were demonstrated when the head position changes from 5-min FLAT to SIT head position (GHP) in mildly affected stroke patients. Importantly, these were associated with non-significant changes in CBFV but reduced measures of CA following AIS, which may be relevant in determining the optimal head position and the ideal timing of mobilisation. Clinical Trial Registration - URL: http://www.clinicaltrials.gov. Unique Identifier: NCT02932540.

Effectiveness of patient education in acute stroke: a comparison between a customised computer system and a pictorial information booklet

Background

Patients who develop acute stroke are at high risk for deterioration in the first 48–72 hours after admission. An effective educational intervention is needed.

Objective

This study aimed to examine the applicability of the customised interactive computer education system (CICS) in patients who had a stroke in the early acute phase in order to determine the efficacy of the education system in (1) information satisfaction and (2) physiological related management compliance.

Methods

The prospective non-blinded randomised controlled study was conducted in an acute stroke unit of a local hospital in Hong Kong from March to August 2019. Chinese participants were selected if they were at least 18 years of age, experienced a minor stroke within 3 days. The exclusion criteria were communication problem and comorbidity with another acute disease. On the first day of admission, participants were allocated to the CICS and booklet groups, with each group comprising 50 participants. On the third day, the primary outcome, Modified Information Satisfaction Questionnaire for Acute Stroke (MISQ-S), was assessed.

Results

There was a significant difference in ‘the need to improve information measures’ of the MISQ-S (p=0.04) between the CICS and booklet groups. The management compliance of these two groups did not have difference, but the CICS group had better clinical outcome, though not significant (p=0.387).

Conclusion

Patient education was needed and feasible in the early acute phase, and the CICS was more efficacious than the booklet. The positive results provided insights into and give a direction to the use of information technology in patient education.

Cerebral haemodynamics with head position changes post-ischaemic stroke: A systematic review and meta-analysis

The effects of upright postures on the cerebral circulation early post-ischaemic stroke are not fully understood. We conducted a systematic review and meta-analysis to investigate the effects of head positioning on cerebral haemodynamics assessed by imaging methods post-ischaemic stroke. Of the 21 studies included (n = 529), 15 used transcranial Doppler. Others used near-infrared, diffuse correlation spectroscopy and nuclear medicine modalities. Most tested head positions between 0° and 45°. Seventeen studies reported changes in CBF parameters (increase at lying-flat or decrease at more upright) in the ischaemic hemisphere with position change. However, great variability was found and risk of bias was high in many studies. Pooled data of two studies ≤24 h (n = 28) showed a mean increase in cerebral blood flow (CBF) velocity of 8.5 cm/s in the ischaemic middle cerebral artery (95%CI,-2.2-19.3) from 30° to 0°. The increase found ≤48 h (n = 50) was of 2.3 cm/s (95%CI,-4.6-9.2), while ≤7 days (n = 38) was of 8.4 cm/s (95%CI, 1.8-15). Few very early studies (≤2 days) tested head positions greater than 30° and were unable to provide information about the response of acute stroke patients to upright postures (sitting, standing). These postures are part of current clinical practice and knowledge on their effects on cerebral haemodynamics is required.

Transient Laterality of Cerebral Oxygenation Changes in Response to Head-of-Bed Manipulation in Acute Ischemic Stroke

Background: Cerebral oxygenation monitoring provides important information for optimizing individualized management in patients with acute ischemic stroke (AIS). Although changes in cerebral oxygenation are known to occur in response to head-of-bed (HOB) elevation within 72 h after onset, changes in cerebral oxygenation during stroke recovery are unclear. We compared changes in total- (tHb), oxygenated- (HbO2), and deoxygenated-hemoglobin (deoxyHb) concentrations in response to HOB manipulation between the timeframes within 72 h and 7–10 days after AIS onset. Methods: We measured forehead ΔtHb, ΔHbO2, and ΔdeoxyHb in response to HOB elevation (30°) within 72 h (first measurement) and 7–10 days (second measurement) after AIS onset using time-resolved near-infrared spectroscopy. Results: We enrolled 30 participants (mean age 72.8 ± 11.3 years; 13 women) with a first AIS. There were no significant differences in ΔtHb, ΔHbO2, or ΔdeoxyHb measurements on the infarct or contra-infarct side. At the first measurement, ΔtHb, ΔHbO2, and ΔdeoxyHb measured on the contra-infarct side did not correlate with those measured on the infarct side: ΔtHb (r = 0.114, p = 0.539); ΔHbO2 (r = 0.143, p = 0.440); ΔdeoxyHb (r = 0.227, p = 0.221). Notably, at the second measurement, correlation coefficients of ΔtHb and ΔHbO2 between the contra-infarct and infarct sides were statistically significant: ΔtHb (r = 0.491, p = 0.008); ΔHbO2 (r = 0.479, p = 0.010); ΔdeoxyHb (r = 0.358, p = 0.054). Conclusion: Although changes in cerebral oxygenation in response to HOB elevation had a laterality difference between hemispheres within 72 h of AIS onset, the difference had decreased, at least partially, 7–10 days after AIS onset.

Cerebral Blood Flow Response During Bolus Normal Saline Infusion After Ischemic Stroke

GOALS

We quantified cerebral blood flow response to a 500 cc bolus of 0.9%% normal saline (NS) within 96 hours of acute ischemic stroke (AIS) using diffuse correlation spectroscopy (DCS).

MATERIALS AND METHODS

Subjects with AIS in the anterior, middle, or posterior cerebral artery territory were enrolled within 96 hours of symptom onset. DCS measured relative cerebral blood flow (rCBF) in the bilateral frontal lobes for 15 minutes at rest (baseline), during a 30-minute infusion of 500 cc NS (bolus), and for 15 minutes after completion (post-bolus). Mean rCBF for each time period was calculated for individual subjects and median rCBF for the population was compared between time periods. Linear regression was used to evaluate for associations between rCBF and clinical features.

RESULTS

Among 57 subjects, median rCBF (IQR) increased relative to baseline in the ipsilesional hemisphere by 17% (-2.0%, 43.1%), P< 0.001, and in the contralesional hemisphere by 13.3% (-4.3%, 36.0%), P < .004. No significant associations were found between ipsilesional changes in rCBF and age, race, infarct size, infarct location, presence of large vessel stenosis, NIH stroke scale, or symptom duration.

CONCLUSION

A 500 cc bolus of .9% NS produced a measurable increase in rCBF in both the affected and nonaffected hemispheres. Clinical features did not predict rCBF response.

Early microvascular cerebral blood flow response to head-of-bed elevation is related to outcome in acute ischemic stroke

BACKGROUND AND AIMS

Previously, microvascular cerebral blood flow (CBF) response to a mild head-of-bed (HOB) elevation has been shown to be altered in acute ischemic stroke (AIS) by diffuse correlation spectroscopy (DCS). We have hypothesized that early CBF response is related to the functional outcome.

METHODS

Patients with a non-lacunar AIS in the anterior circulation were monitored by DCS to measure relative CBF (ΔrCBF) on the frontal lobes bilaterally during a 0°-30° HOB elevation at early (≤ 12) or late (> 12) hours from symptom onset. National Institutes of Health Stroke Scale (NIHSS) scores were recorded at baseline at 24 and at 48 h. Functional outcome was measured by the modified Rankin Scale (mRS) at 3 months.

RESULTS

Thirty-eight (n = 38) AIS patients [baseline NIHSS = 19 (interquartile range: 16, 21)] were studied. ΔrCBF decreased similarly in both hemispheres (p = 0.4) when HOB was elevated and was not associated with baseline and follow-up NIHSS scores or patient demographics. At the early phase (n = 17), a lower or paradoxical ΔrCBF response to HOB elevation was associated with an unfavorable functional outcome (mRS > 2) in the ipsilesional (but not in the contralesional) hemisphere (p = 0.010). ΔrCBF response in the late acute phase was not related to mRS.

CONCLUSIONS

Early CBF response to mild HOB elevation in the ipsilesional hemisphere is related to functional outcome. Further studies may enable optical monitoring at the bedside to individualize management strategies in the early phase of AIS.

The practice and predictors of early mobilization of patients post-acute admission to a specialized stroke center

BACKGROUND

Early mobilization (EM) post-stroke is recommended; however, the ideal timing and nature of EM, and factors that may influence EM practice are unclear.

OBJECTIVES

The primary objective was to describe the type and extent of mobilization 0-48 h post-stroke admission to acute hospital care. A secondary objective was to evaluate whether pre-stroke functional level, stroke severity, tissue plasminogen activator (tPA) administration, and level of consciousness (LOC) predicted any passive, any active, and out-of-bed mobilization (i.e. sitting at edge-of-bed, standing, or ambulation) 0-24 h post-admission.

METHODS

A quantitative, cross-sectional, retrospective review of health records of patients admitted to a specialized acute stroke center in 2016 was conducted.

RESULTS

Data from 296 eligible health records were abstracted. Median age was 73 years, and 87% of patients had sustained an ischemic stroke. Active, passive, and out-of-bed mobilization occurred in 91.6%, 57.1%, and 24.3% of patients by 12 h post-admission, respectively, and 99.3%, 78.4%, and 77.4% of patients by 48 h post-admission, respectively. Administration of tPA, stroke severity, and impaired LOC, were each associated with any passive mobilization, and no tPA administration, stroke severity, and normal LOC were each associated with out-of-bed mobilization 0-24 h post-admission (p < 0.05).

CONCLUSIONS

Almost all patients receive active mobilization by 12 h post-admission whereas out-of-bed mobilization is infrequent. In the first 24 h post-admission, clinicians may prioritize passive over out-of-bed mobilization when patients have received tPA, present with severe stroke, and have impaired LOC. This conservative approach is unsurprising given the lack of clear practice recommendations for these situations.

Cerebral autoregulatory performance and the cerebrovascular response to head-of-bed positioning in acute ischaemic stroke

Background and purpose

Cerebrovascular responses to head‐of‐bed positioning in patients with acute ischaemic stroke are heterogeneous, questioning the applicability of general recommendations on head positioning. Cerebral autoregulation is impaired to various extents after acute stroke, although it is unknown whether this affects cerebral perfusion during posture change. We aimed to elucidate whether the cerebrovascular response to head position manipulation depends on autoregulatory performance in patients with ischaemic stroke.

Methods

The responses of bilateral transcranial Doppler ultrasound‐determined cerebral blood flow velocity (CBFV) and local cerebral blood volume (CBV), assessed by near‐infrared spectroscopy of total hemoglobin tissue concentration ([total Hb]), to head‐of‐bed lowering from 30° to 0° were determined in 39 patients with acute ischaemic stroke and 17 reference subjects from two centers. Cerebrovascular autoregulatory performance was expressed as the phase difference of the arterial pressure‐to‐CBFV transfer function.

Results

Following head‐of‐bed lowering, CBV increased in the reference subjects only ([total Hb]: + 2.1 ± 2.0 vs. + 0.4 ± 2.6 μM; P < 0.05), whereas CBFV did not change in either group. CBV increased upon head‐of‐bed lowering in the hemispheres of patients with autoregulatory performance <50th percentile compared with a decrease in the hemispheres of patients with better autoregulatory performance ([total Hb]: +1.0 ± 1.3 vs. −0.5 ± 1.0 μM; P < 0.05). The CBV response was inversely related to autoregulatory performance (r = −0.68; P < 0.001) in the patients, whereas no such relation was observed for CBFV.

Conclusion

This study is the first to provide evidence that cerebral autoregulatory performance in patients with acute ischaemic stroke affects the cerebrovascular response to changes in the position of the head.

Guidelines for evaluation and management of cerebral collateral circulation in ischaemic stroke 2017

Collateral circulation plays a vital role in sustaining blood flow to the ischaemic areas in acute, subacute or chronic phases after an ischaemic stroke or transient ischaemic attack. Good collateral circulation has shown protective effects towards a favourable functional outcome and a lower risk of recurrence in stroke attributed to different aetiologies or undergoing medical or endovascular treatment. Over the past decade, the importance of collateral circulation has attracted more attention and is becoming a hot spot for research. However, the diversity in imaging methods and criteria to evaluate collateral circulation has hindered comparisons of findings from different cohorts and further studies in exploring the clinical relevance of collateral circulation and possible methods to enhance collateral flow. The statement is aimed to update currently available evidence and provide evidence-based recommendations regarding grading methods for collateral circulation, its significance in patients with stroke and methods under investigation to improve collateral flow.

HeadPoST

Objective

To critique the Head Positioning in Stroke Trial (HeadPoST) study methods in relation to preceding research findings in an aim to clarify the potential efficacy of positioning interventions and direction for future research.

Methods

Head positioning research prior to the conduct of HeadPoST was reviewed by a team of international stroke experts, and methods and findings were compared to HeadPoST.

Results

Methods used to select HeadPoST patients differ substantially from those used in original head positioning studies, in particular enrollment of all types of stroke. HeadPoST enrolled primarily minor strokes (median NIH Stroke Scale 4, interquartile range [IQR] 2–8) without vascular imaging confirmation of subtype; elapsed time from stroke symptom onset to the initiation of intervention was late (median 14 hours, IQR 5–35), and time from hospital admission to enrollment was delayed (median 7 hours, IQR 2–26). Intervention integrity was not reported, including ability to achieve/maintain 30° head elevation in beds lacking head elevation capabilities. Deterioration or improvement associated with the intervention is unknown as serial assessments were not completed, and the trial's 3-month outcome was powered using unrelated study data.

Conclusions

The design of HeadPoST was suboptimal to measure differences produced by the intervention. Future head positioning trials in discrete patient cohorts (in particular, large vessel occlusion) with endpoints supported by pilot work are required to understand the efficacy of this simple yet potentially important intervention.

Does gradual change in head positioning affect cerebrovascular physiology?

We studied cerebral blood velocity (CBV), and associated hemodynamic parameters during gradual changes in head positioning in a nonstroke group. CBV (transcranial Doppler ultrasound), beat-to-beat blood pressure (BP, Finometer), and end-tidal carbon dioxide (ETCO2 , capnography) were recorded between lying flat (0°) and sitting up (30°) head positions, in 18 volunteers (10 female, mean age, 57 ± 16 years), at two visits (12 ± 8 days). A significant reduction was found between 5-min FLAT (0°) and 5-min SIT (30°) positions in CBV (visit 1: 4.5 ± 3.3%, P = 0.006; visit 2: 4.1 ± 3.5%, P = 0.003), critical closing pressure (CrCP; visit 1: 15.5 ± 14.0%, P = 0.0002; visit 2: 14.1 ± 7.8%, P = 0.009) and BP (visit 1: 8.3 ± 7.4%, P = 0.001; visit 2: 11.0 ± 11.3%, P < 0.001). For 5 min segments of data, the autoregulation index and other hemodynamic parameters did not show differences either due to head position or visit. For 30 sec time intervals, significant differences were observed in the following: (BP, P < 0.001; dominant hemisphere (DH) CBV, P < 0.005; nondominant hemisphere (NDH) CBV, P < 0.005; DH CrCP, P < 0.001; NDH CrCP, P < 0.001; DH resistance area product (RAP), P = 0.002; NDH RAP, P = 0.033). Significant static changes in BP, CBV and CrCP, and large transient changes in key hemodynamic parameters occur during 0° to 30°, and vice versa, with reproducible results. Further studies are needed following acute ischemic stroke to determine if a similar responses is present.

Is the proportional recovery rule applicable to the lower limb after a first-ever ischemic stroke?

OBJECTIVE

To investigate (a) the applicability of the proportional recovery rule of spontaneous neurobiological recovery to motor function of the paretic lower extremity (LE); and (b) the presence of fitters and non-fitters of this prognostic rule poststroke. When present, the clinical threshold for fitting nor non-fitting would be determined, as well as within-subject generalizability to the paretic upper extremity (UE).

METHODS

Prospective cohort study in which the Fugl-Meyer Assessment (FMA)-LE and FMA-UE were measured <72 hours and 6 months poststroke. Predicted maximum potential recovery was defined as [FMA-LEmax-FMA-LEinitial = 34 -FMA-LEinitial]. Hierarchical clustering in 202 first-ever ischemic stroke patients distinguished between fitting and not fitting the rule. Descriptive statistics determined whether fitters and non-fitters for LE were the same persons as for UE.

RESULTS

175 (87%) patients fitted the FMA-LE recovery rule. The observed average improvement of the fitters was ~64% of the predicted maximum potential recovery. In the non-fitter group, the maximum initial FMA-LE score was 13 points. Fifty-one out of 78 patients (~65%) who scored below the identified 14-point threshold at baseline fitted the FMA-LE rule. Non-fitters were more severely affected than fitters. All non-fitters of the FMA-LE rule did also not fit the proportional recovery rule for FMA-UE.

CONCLUSIONS

Proportional recovery seems to be consistent within subjects across LE and UE motor impairment at the hemiplegic side in first-ever ischemic hemispheric stroke subjects. Future studies should investigate prospectively distinguishing between fitters and not-fitters within the subgroup of patients who have initial low FMA-LE scores. Subsequently, patients could be stratified based on fitting or not fitting the recovery rule as this would impact rehabilitation management and trial design.

Flat-head positioning increases cerebral blood flow in anterior circulation acute ischemic stroke. A cluster randomized phase IIb trial

Background

Whether lying-flat improves blood flow in patients with acute ischemic stroke is unknown. Our aim was to investigate if lying-flat “changes” cerebral blood flow velocities assessed by transcranial Doppler in acute ischemic stroke patients.

Methods

In a multicenter cluster clinical trial, we randomly assigned patients within 12 h from onset of a neurological deficit due to cerebral ischemia of the anterior circulation to lying-flat or upright head positioning. The primary outcome was a change of 8 cm/s or more in mean cerebral blood flow velocities on transcranial Doppler to the middle cerebral artery at 1 and 24 h post-randomization, adjusted for imbalance in baseline variables. Secondary outcomes included serious adverse events and physical functioning at 90 days.

Results

Ninety-four of 304 patients screened were recruited. The primary outcome occurred in 11 (26%) of 43 patients in the lying-flat group and in 6 (12%) of 51 in the upright group at 1 h (adjusted odds ratio, 3.81; 95% CI, 1.07 to 13.54), and in 23 (53%) and 18 (36%) patients in these respective groups at 24 h (adjusted odds ratio, 3.04; 95% CI, 1.08 to 8.53). There were no between-group differences in serious adverse events, including pneumonia, heart failure or mortality, nor in functional outcome at 3 months (adjusted common odds ratio, 1.38; 95% CI 0.64 to 3.00).

Conclusion

The lying-flat head position was associated with a significant increase in cerebral blood flow velocities at one and 24 h within the ipsilateral hemisphere of anterior circulation acute ischemic stroke, without serious safety concerns. Clinical trial registration-URL: http://www.clinicaltrials.gov . Unique identifier: NCT01706094.

Statistical analysis plan of the head position in acute ischemic stroke trial pilot (HEADPOST pilot)

Background The HEADPOST Pilot is a proof-of-concept, open, prospective, multicenter, international, cluster randomized, phase IIb controlled trial, with masked outcome assessment. The trial will test if lying flat head position initiated in patients within 12 h of onset of acute ischemic stroke involving the anterior circulation increases cerebral blood flow in the middle cerebral arteries, as measured by transcranial Doppler. The study will also assess the safety and feasibility of patients lying flat for ≥24 h. The trial was conducted in centers in three countries, with ability to perform early transcranial Doppler. A feature of this trial was that patients were randomized to a certain position according to the month of admission to hospital. Objective To outline in detail the predetermined statistical analysis plan for HEADPOST Pilot study. Methods All data collected by participating researchers will be reviewed and formally assessed. Information pertaining to the baseline characteristics of patients, their process of care, and the delivery of treatments will be classified, and for each item, appropriate descriptive statistical analyses are planned with comparisons made between randomized groups. For the outcomes, statistical comparisons to be made between groups are planned and described. Results This statistical analysis plan was developed for the analysis of the results of the HEADPOST Pilot study to be transparent, available, verifiable, and predetermined before data lock. Conclusions We have developed a statistical analysis plan for the HEADPOST Pilot study which is to be followed to avoid analysis bias arising from prior knowledge of the study findings. Trial registration The study is registered under HEADPOST-Pilot, ClinicalTrials.gov Identifier NCT01706094.

Acute Stroke: Current Evidence-based Recommendations for Prehospital Care

Introduction

In the United States, emergency medical services (EMS) protocols vary widely across jurisdictions. We sought to develop evidence-based recommendations for the prehospital evaluation and treatment of a patient with a suspected stroke and to compare these recommendations against the current protocols used by the 33 EMS agencies in the state of California.

Methods

We performed a literature review of the current evidence in the prehospital treatment of a patient with a suspected stroke and augmented this review with guidelines from various national and international societies to create our evidence-based recommendations. We then compared the stroke protocols of each of the 33 EMS agencies for consistency with these recommendations. The specific protocol components that we analyzed were the use of a stroke scale, blood glucose evaluation, use of supplemental oxygen, patient positioning, 12-lead electrocardiogram (ECG) and cardiac monitoring, fluid assessment and intravenous access, and stroke regionalization.

Results

Protocols across EMS agencies in California varied widely. Most used some sort of stroke scale with the majority using the Cincinnati Prehospital Stroke Scale (CPSS). All recommended the evaluation of blood glucose with the level for action ranging from 60 to 80mg/dL. Cardiac monitoring was recommended in 58% and 33% recommended an ECG. More than half required the direct transport to a primary stroke center and 88% recommended hospital notification.

Conclusion

Protocols for a patient with a suspected stroke vary widely across the state of California. The evidence-based recommendations that we present for the prehospital diagnosis and treatment of this condition may be useful for EMS medical directors tasked with creating and revising these protocols.

Risk of pneumonia associated with zero-degree head positioning in acute ischemic stroke patients treated with intravenous tissue plasminogen activator

INTRODUCTION

In the hyperacute phase of ischemic stroke, a 0° position is recommended to increase cerebral perfusion in nonhypoxic patients able to tolerate lying flat. However, use of 0° positioning is not uniformly applied in clinical practice, most likely due to concerns of aspiration pneumonia. We aimed to determine the risk of pneumonia associated with 0° head of bed positioning in acute stroke patients treated with thrombolytic therapy.

METHODS

A retrospective descriptive study was conducted using prospectively collected, consecutive acute ischemic stroke patients treated with IVtPA whose head of bed was positioned at 0° for the first 24 h. Rates of hospital-acquired pneumonia were determined using a strict adjudication process to insure accuracy of pneumonia diagnoses. Quantitative characteristics were analyzed in SPSS to compare differences between "true" pneumonia cases and nonpneumonia cases.

RESULTS

Twenty-four of 333 (7.2%) patients had mention the diagnosis of pneumonia in the registry and/or medical record. Of these cases, only 15 (4.5%) met evidence-based diagnostic criteria for hospital-acquired pneumonia. The 15 adjudicated cases had similar median admission NIHSS scores to nonpneumonia cases (10 vs. 9, respectively; P = ns), but were older (74 ± 15 vs. 64 ± 17 years; mean difference 9.889, 95 CI = 1.2-18.6; P = 0.026). A total of eight patients with pneumonia were intubated and mechanically ventilated, and one patient received bilevel positive airway pressure ventilation during the 0° positioning period. Pneumonia cases had significantly longer hospitalizations (14.5 ± 12 vs. 6.6 ± 9 days; mean difference 7.97, 95% CI = 1.1-14.8; P = 0.026) and higher median discharge mRS score (4 vs. 3: P = 0.003).

CONCLUSIONS

Zero-degree head of bed positioning in the first 24 h following an acute ischemic stroke treated with IV-tPA was associated with acceptable rates of pneumonia. Rates for pneumonia may be further reduced by eliminating use of a 0° protocol in intubated/mechanically ventilated patients.

Head position and cerebral blood flow in acute ischemic stroke patients: Protocol for the pilot phase, cluster randomized, Head Position in Acute Ischemic Stroke Trial (HeadPoST pilot)

Rationale

Few proven interventions exist for acute ischemic stroke (AIS), and most are expensive and restricted in applicability. Lying flat ‘head down’ positioning of AIS patients has been shown to increase by as much as 20%, mean cerebral blood flow velocities (CBFV) measured by transcranial Doppler (TCD) but whether this translates into clinical improvement is uncertain.

Aim

To determine if the lying flat position increases mean CBFV in the affected territory as compared to the sitting up position in AIS patients.

Methods and design

Head Position in Acute Ischemic Stroke Trial (HeadPoST pilot) is a cluster randomized (clusters being months), assessor-blinded end-point, phase IIb trial, where consecutive adults with anterior circulation AIS within 12 h of symptom onset are positioned to a randomized position for 48 h with TCD performed serially.

Study outcomes

Primary outcome is mean CBFV on TCD at 1 and 24 h after positioning. Secondary outcomes include: serious adverse events, neurological impairment at seven days, and death and disability at 90 days.

Sample size estimates

Assuming an increase of 8.3 (SD 11.4) cm/s in average of mean CBFV when tilted from 30° to 0°, 46 clusters are required (92 patients in total) to detect a 20% increase of mean CBFV with 90% power and 5% level of significance.

Conclusion

HeadPoST pilot is a cluster randomized multicenter clinical trial investigating the effect of head positioning on mean CBFV in anterior circulation AIS.

Proxy study on minimizing risk of sacral pressure ulcers while complying with ventilator-associated pneumonia risk reduction guidelines

Bed positioning poses a subtle, yet important, tradeoff in the competing needs of hospitalized patients, particularly those susceptible to lower respiratory tract infections and/or pressure ulcers. Although it is widely held that a minimum 30° incline is necessary to mitigate risk of ventilator-acquired pneumonia, it is unclear what effect semirecumbent positioning has on the risk of pressure ulcerations. The authors test several hypotheses with the objective of elucidating the relationship between bed incline, posture, and incline, pursuant to a more evidence-based recommendation for practice in clinical care. To this end, interfacial pressures from 40 healthy subjects were analyzed following observation in both supine and sidelying positions, at shallow (30°) and moderate (45°) bed-angle incline. Summarily, the authors report that supine postures reduce pressure signatures associated with pressure ulceration versus sidelying position: 15% increase area of contact (P = 1.3×10), and 17% decrease in ratio of peak to average pressure (P = 3.1×10). Within supine posture, the authors found significant increases in 4 measures of local pressure, including average pressure (10.4% decrease, P = .005) and coefficient of pressure variation (22.1%, P = 2.2×10) at moderate incline. The authors conclude that supine bed positionings at moderate incline appear to reduce predictors of pressure ulceration.

Head Position in Stroke Trial (HeadPoST)--sitting-up vs lying-flat positioning of patients with acute stroke: study protocol for a cluster randomised controlled trial

Background

Positioning a patient lying-flat in the acute phase of ischaemic stroke may improve recovery and reduce disability, but such a possibility has not been formally tested in a randomised trial. We therefore initiated the Head Position in Stroke Trial (HeadPoST) to determine the effects of lying-flat (0°) compared with sitting-up (≥30°) head positioning in the first 24 hours of hospital admission for patients with acute stroke.

Methods/Design

We plan to conduct an international, cluster randomised, crossover, open, blinded outcome-assessed clinical trial involving 140 study hospitals (clusters) with established acute stroke care programs. Each hospital will be randomly assigned to sequential policies of lying-flat (0°) or sitting-up (≥30°) head position as a ‘business as usual’ stroke care policy during the first 24 hours of admittance. Each hospital is required to recruit 60 consecutive patients with acute ischaemic stroke (AIS), and all patients with acute intracerebral haemorrhage (ICH) (an estimated average of 10), in the first randomised head position policy before crossing over to the second head position policy with a similar recruitment target. After collection of in-hospital clinical and management data and 7-day outcomes, central trained blinded assessors will conduct a telephone disability assessment with the modified Rankin Scale at 90 days. The primary outcome for analysis is a shift (defined as improvement) in death or disability on this scale. For a cluster size of 60 patients with AIS per intervention and with various assumptions including an intracluster correlation coefficient of 0.03, a sample size of 16,800 patients at 140 centres will provide 90 % power (α 0.05) to detect at least a 16 % relative improvement (shift) in an ordinal logistic regression analysis of the primary outcome. The treatment effect will also be assessed in all patients with ICH who are recruited during each treatment study period.

Discussion

HeadPoST is a large international clinical trial in which we will rigorously evaluate the effects of different head positioning in patients with acute stroke.

Trial registration

ClinicalTrials.gov identifier: NCT02162017 (date of registration: 27 April 2014); ANZCTR identifier: ACTRN12614000483651 (date of registration: 9 May 2014). Protocol version and date: version 2.2, 19 June 2014.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-015-0767-1) contains supplementary material, which is available to authorized users.

Early mobilization in ischemic stroke: a pilot randomized trial of safety and feasibility in a public hospital in Brazil

Background

The effect of early mobilization after acute stroke is still unclear, although some studies have suggested improvement in outcomes. We conducted a randomized, single-blind, controlled trial seeking to evaluate the feasibility, safety, and benefit of early mobilization for patients with acute ischemic stroke treated in a public teaching hospital in Southern Brazil. This report presents the feasibility and safety findings for the pilot phase of this trial.

Methods

The primary outcomes were time to first mobilization, total duration of mobilization, complications during early mobilization, falls within 3 months, mortality within 3 months, and medical complications of immobility. We included adult patients with CT- or MRI-confirmed ischemic stroke within 48 h of symptom onset who were admitted from March to November 2012 to the acute vascular unit or general emergency unit of a large urban emergency department (ED) at the Hospital de Clínicas de Porto Alegre. The severity of the neurological deficit on admission was assessed by the National Institutes of Health Stroke Scale (NIHSS). The NIHSS and modified Rankin Scale (mRS, functional outcome) scores were assessed on day 14 or at discharge as well as at 3 months. Activities of daily living (ADL) were measured with the modified Barthel Index (mBI) at 3 months.

Results

Thirty-seven patients (mean age 65 years, mean NIHSS score 11) were randomly allocated to an intervention group (IG) or a control group (CG). The IG received earlier (p = 0.001) and more frequent (p < 0.0001) mobilization than the CG. Of the 19 patients in the CG, only 5 (26%) underwent a physical therapy program during hospitalization. No complications (symptomatic hypotension or worsening of neurological symptoms) were observed in association with early mobilization. The rates of complications of immobility (pneumonia, pulmonary embolism, and deep vein thrombosis) and mortality were similar in the two groups. No statistically significant differences in functional independence, disability, or ADL (mBI ≥85) were observed between the groups at the 3-month follow-up.

Conclusions

This pilot trial conducted at a public hospital in Brazil suggests that early mobilization after acute ischemic stroke is safe and feasible. Despite some challenges and limitations, early mobilization was successfully implemented, even in the setting of a large, complex ED, and without complications. Patients from the IG were mobilized much earlier than controls receiving the standard care provided in most Brazilian hospitals.

Optical bedside monitoring of cerebral blood flow in acute ischemic stroke patients during head-of-bed manipulation

BACKGROUND AND PURPOSE

A primary goal of acute ischemic stroke (AIS) management is to maximize perfusion in the affected region and surrounding ischemic penumbra. However, interventions to maximize perfusion, such as flat head-of-bed (HOB) positioning, are currently prescribed empirically. Bedside monitoring of cerebral blood flow (CBF) allows the effects of interventions such as flat HOB to be monitored and may ultimately be used to guide clinical management.

METHODS

Cerebral perfusion was measured during HOB manipulations in 17 patients with unilateral AIS affecting large cortical territories in the anterior circulation. Simultaneous measurements of frontal CBF and arterial flow velocity were performed with diffuse correlation spectroscopy and transcranial Doppler ultrasound, respectively. Results were analyzed in the context of available clinical data and a previous study.

RESULTS

Frontal CBF, averaged over the patient cohort, decreased by 17% (P=0.034) and 15% (P=0.011) in the ipsilesional and contralesional hemispheres, respectively, when HOB was changed from flat to 30°. Significant (cohort-averaged) changes in blood velocity were not observed. Individually, varying responses to HOB manipulation were observed, including paradoxical increases in CBF with increasing HOB angle. Clinical features, stroke volume, and distance to the optical probe could not explain this paradoxical response.

CONCLUSIONS

A lower HOB angle results in an increase in cortical CBF without a significant change in arterial flow velocity in AIS, but there is variability across patients in this response. Bedside CBF monitoring with diffuse correlation spectroscopy provides a potential means to individualize interventions designed to optimize CBF in AIS.

Cerebral blood flow velocity changes during upright positioning in bed after acute stroke: an observational study

OBJECTIVES

National guidelines recommend mobilisation in bed as early as possible after acute stroke. Little is known about the influence of upright positioning on real-time cerebral flow variables in patients with stroke. We aimed to assess whether cerebral blood flow velocity (CBFV) changes significantly after upright positioning in bed in the acute stroke phase.

DESIGN

Observational study.

PARTICIPANTS

47 patients with acute ischaemic stroke measured in the subacute phase after symptom onset and 20 healthy controls.

PRIMARY AND SECONDARY OUTCOME MEASURES

We recorded postural changes in bilateral transcranial Doppler (primary outcome) and simultaneously recorded near-infrared spectroscopy, end-tidal CO2, non-invasive blood pressure data and changes in neurological status (secondary outcomes).

METHODS

Postures included the supine, half sitting (45°), sitting (70°) and Trendelenburg (-15°) positions. Using multilevel analyses, we compared postural changes between hemispheres, outcome groups (using modified Rankin Scale) as well as between patients and healthy controls.

RESULTS

The mean patient age was 62±15 years and median National Institute of Health Stroke Scale score on admission was 7 (IQR 5-14). Mean proportional CBFV changes on sitting were not significantly different between healthy controls and affected hemispheres in patients with stroke. No significant differences were found between affected and unaffected stroke hemispheres and between patients with unfavourable and favourable outcomes. During upright positioning, no neurological worsening or improvement was observed in any of the patients.

CONCLUSIONS

No indications were found that upright positioning in bed in mild to moderately affected patients with stroke compromises flow and (frontal)oxygenation significantly during the subacute phase of stroke. Supine or Trendelenburg positioning does not seem to augment real-time flow variables.

Effects of a head-down tilt on cerebral blood flow in mice during bilateral common carotid artery occlusion

Objectives:

Data on the optimal head position for patients with acute ischemic stroke are unavailable. We evaluated the effects of mild head-down tilt (HDT) on cerebral blood flow (CBF) in mice during bilateral common carotid artery occlusion (BCCAO).

Materials and Methods:

We used mice with BCCAO (35 minutes) and divided these into 2 groups ( n=16): BCCAO at 0°-HDT and 5°-HDT. CBF was measured for both hemispheres with a non-invasive laser Doppler blood perfusion imager. Changes in CBF during BCCAO were examined in both groups.

Results:

A significantly greater increase in CBF in both hemispheres was observed in 5°-HDT mice than in 0°-HDT mice (126.1% (8.715)% vs. 102.1% (4.718)%; P=0.0294).

Conclusion:

HDT enhanced the increase in CBF in both hemispheres in the mouse BCCAO model. The potential mechanism underlying CBF increase enhanced by HDT during BCCAO warrants further investigation.