What is the clinical evidence from this study?

Study design: RCT. Population: Healthy (n=11). Intervention: Phenylephrine vs. Saline flush / Baseline. Primary outcome: Significant BOLD signal changes in brainstem nuclei correlated with systolic blood pressure (p=<0.0005).

March 5, 2019Frontiers in NeuroscienceOpen Access

Novel Approach to Elucidate Human Baroreflex Regulation at the Brainstem Level: Pharmacological Testing During fMRI

Q: What are the key findings of this study?

Pharmacological baroreflex loading with phenylephrine during fMRI identified significant signal changes in key brainstem nuclei, including the nucleus tractus solitarii (t=5.97) and rostral ventrolateral medulla (t=7.11).

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Key result

Pharmacological baroreflex loading with phenylephrine during fMRI identified significant signal changes in key brainstem nuclei, including the nucleus tractus solitarii (t=5.97) and rostral ventrolateral medulla (t=7.11).

Why the study?

Brainstem nuclei govern the arterial baroreflex, but brainstem function is difficult to explore in living humans and is mostly studied using animal models or postmortem human anatomy studies.

Comparison

Intravenous phenylephrine bolus doses of 25 µg and 75 µg during multiband functional MRI

Design

Methodological pharmacological fMRI study

Authors

DGDarius A. GerlachDeutsches Zentrum für Luft- und Raumfahrt e. V. (DLR)JMJorge ManuelDeutsches Zentrum für Luft- und Raumfahrt e. V. (DLR)AHAlex HoffDeutsches Zentrum für Luft- und Raumfahrt e. V. (DLR)

Discussion

Member takes

Implication

Hypothesis-generating for brainstem baroreflex fMRI in animals; leaves open human translation and clinical relevance.

Study Design

Type

RCT (n=11)

Randomization

Randomized order of doses

Multicenter

Structured PICO

Population

11 healthy, normotensive, non-smoking men with a mean age of 30.5 years underwent pharmacological baroreflex testing during fMRI.

Intervention

Eight repeated intravenous phenylephrine bolus doses of 25 µg and 75 µg followed by a saline flush during multiband functional MRI acquisition

Outcome

Identification of brainstem nuclei involved in central integration of the baroreceptor input via fMRI signal changessurrogate

Main Result

p-value: p=<0.0005

Pharmacological baroreflex testing during fMRI can successfully identify and characterize central baroreflex regulation at the brainstem level in living humans.

Limitations

Phenylephrine may indirectly or directly affect cerebral circulation, which could confound fMRI analysis.
The number of subjects is relatively low (n=11), which may limit generalizability.
Spatial resolution of 2 mm isotropic limits the ability to clearly separate nuclei that are in close vicinity.

Cite This Study

Gerlach et al. (2019) conducted an RCT in Healthy (n=11). Phenylephrine vs. Saline flush / Baseline was evaluated on Significant BOLD signal changes in brainstem nuclei correlated with systolic blood pressure (p=<0.0005). Pharmacological baroreflex loading with phenylephrine during fMRI identified significant signal changes in key brainstem nuclei, including the nucleus tractus solitarii (t=5.97) and rostral ventrolateral medulla (t=7.11).

synapsesocial.com/papers/6a7324a810f44d800ec8d5e0 https://doi.org/10.3389/fnins.2019.00193

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Novel Approach to Elucidate Human Baroreflex Regulation at the Brainstem Level: Pharmacological Testing During fMRI

Discussion

Member takes

Implication

Study Design

Structured PICO

Main Result

Limitations

Cite This Study

Novel Approach to Elucidate Human Baroreflex Regulation at the Brainstem Level: Pharmacological Testing During fMRI

Discussion

Member takes

Implication

Study Design

Structured PICO

Main Result

Limitations

Cite This Study

Also Consider

Also Consider