Phenylephrine and paradoxically increased muscle tissue oxygenation: is the mechanism related to local venoconstriction or augmented venous return?

Grocott, Hilary P.

doi:10.1007/s10877-018-0102-y

Cited by 3 publications

(1 citation statement)

References 4 publications

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“…The authors conclude that phenylephrine redistributed blood flow from the extremities towards the central compartment, and speculate that the paradoxical increase in SmO 2 was caused by constriction of the venous part of the muscular vessels, changing the local ratio between oxygenated and deoxygenated blood within the muscle. This postulated mechanism was questioned in a letter by Grocott [23], who also added the possible explanation that phenylephrine may have augmented venous return (and thus cardiac output and muscle oxygen delivery). In their response, Sørensen et al [24] quote data from a follow-up study where they could show that phenylephrine actually increased SmO 2 by augmenting local oxy-hemoglobin concentration while decreasing that of de-oxyhemoglobin.…”

Section: Nirs-derived Variables and Outcomementioning

confidence: 99%

Journal of Clinical Monitoring and Computing 2017/2018 end of year summary: monitoring—and provocation—of the microcirculation and tissue oxygenation

Vos

Ellermann

Scheeren

2019

J Clin Monit Comput

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The microcirculation is the ultimate goal of hemodynamic optimization in the perioperative and critical care setting. In this fourth end-of-year summary of the Journal of Clinical Monitoring and Computing on this topic, we take a closer look at papers published in the last 2 years that focus on this important aspect. The majority of these papers investigated the use of either cerebral or peripheral tissue oxygen saturation, derived non-invasively using near infrared spectroscopy (NIRS). In some of these studies, the microcirculation was “provocated” by inducing short-term tissue hypoxia, allowing the assessment of functional microvascular reserve. Additionally, studies on technical differences between NIRS monitors are summarized, as well as studies investigating the feasibility of NIRS monitoring, mainly in the pediatric patient population. Last but not least, novel monitoring tools allow assessing oxygenation at a (sub)cellular level, and those papers incorporating these techniques are also reviewed here.

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Section: Nirs-derived Variables and Outcomementioning

confidence: 99%

Journal of Clinical Monitoring and Computing 2017/2018 end of year summary: monitoring—and provocation—of the microcirculation and tissue oxygenation

Vos

Ellermann

Scheeren

2019

J Clin Monit Comput

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In response to: phenylephrine and paradoxically increased muscle tissue oxygenation: is the mechanism related to local venoconstriction or augmented venous return?

Sørensen

Egesborg

Thomsen

et al. 2018

J Clin Monit Comput

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In vivo optical assessment of cerebral and skeletal muscle microvascular response to phenylephrine

Mawdsley,

Eskandari,

Kamar

et al. 2024

FASEB BioAdvances

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This study aimed to investigate the simultaneous response of the cerebral and skeletal muscle microvasculature to the same phenylephrine (PE) boluses. A hybrid optical system that combines hyperspectral near‐infrared spectroscopy (hs‐NIRS) and diffuse correlation spectroscopy (DCS) was used to monitor changes in tissue oxygenation and perfusion. Data were collected from the head and hind limb of seven male Sprague–Dawley rats while administering intravenous (IV) injections of PE or saline to all animals. The response to saline was used as a control. Skeletal muscle oxygenation decreased significantly after PE injection, while a statistically underpowered decrease in perfusion was observed, followed by an increase beyond baseline. Vascular conductance also decreased in the muscle reflecting the drug's vasoconstrictive effects. Tissue oxygenation and perfusion increased in the brain in response to PE. Initially, there was a sharp increase in cerebral perfusion but no changes in cerebral vascular conductance. Subsequently, cerebral flow and vascular conductance decreased significantly below baseline, likely reflecting autoregulatory mechanisms to manage the excess flow. Further, fitting an exponential function to the secondary decrease in cerebral perfusion and increase in muscular blood flow revealed a quicker kinetic response in the brain to adjust blood flow. In the skeletal muscle, PE caused a transient decrease in blood volume due to vasoconstriction, which resulted in an overall decrease in hemoglobin content and tissue oxygen saturation. Since PE does not directly affect cerebral vessels, this peripheral vasoconstriction shunted blood into the brain, resulting in an initial increase in oxygenated hemoglobin and oxygen saturation.

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Phenylephrine and paradoxically increased muscle tissue oxygenation: is the mechanism related to local venoconstriction or augmented venous return?

Cited by 3 publications

References 4 publications

Journal of Clinical Monitoring and Computing 2017/2018 end of year summary: monitoring—and provocation—of the microcirculation and tissue oxygenation

Journal of Clinical Monitoring and Computing 2017/2018 end of year summary: monitoring—and provocation—of the microcirculation and tissue oxygenation

In response to: phenylephrine and paradoxically increased muscle tissue oxygenation: is the mechanism related to local venoconstriction or augmented venous return?

In vivo optical assessment of cerebral and skeletal muscle microvascular response to phenylephrine

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