Large-dose epinephrine reduces skeletal muscle blood flow under general anesthesia in rabbits

Hemodynamic changes in the temporalis and masseter muscles during acute stress in healthy humans

PURPOSE

Autonomic control of orofacial areas is an integral part of the stress response, controlling functions such as pupil dilatation, salivation, and skin blood flow. However, the specific control of blood flow in head muscles during stress is unknown. This study aims to investigate the hemodynamic response of temporalis and masseter muscles in response to five different stressors.

METHODS

Sixteen healthy individuals were subjected to a randomized series of stressors, including cold pressor test, mental arithmetic test, apnea, isometric handgrip, and post-handgrip muscle ischemia, while in the sitting posture. Finger-pulse photoplethysmography was used to measure arterial blood pressure, heart rate, and cardiac output. Near-infrared spectroscopy was used to measure changes in tissue oxygenation and hemoglobin indices from the temporalis and masseter muscles.

RESULTS

All stressors effectively and significantly increased arterial blood pressure. Tissue oxygenation index significantly increased in both investigated head muscles during mental arithmetic test (temporalis: 4.22 ± 3.52%; masseter: 3.43 ± 3.63%) and isometric handgrip (temporalis: 3.45 ± 3.09%; masseter: 3.26 ± 3.07%), suggesting increased muscle blood flow. Neither the masseter nor the temporalis muscles evidenced a vasoconstrictive response to any of the stressors tested.

CONCLUSION

In the different conditions, temporalis and masseter muscles exhibited similar hemodynamic patterns of response, which do not include the marked vasoconstriction generally observed in limb muscles. The peculiar sympathetic control of head muscles is possibly related to the involvement of these muscles in aggressive/defensive reactions and/or to their unfavorable position with regard to hydrostatic blood levels.

Involvement of α- and β-Adrenergic Receptors in Skeletal Muscle Blood Flow Changes During Hyper-/Hypocapnia in Anesthetized Rabbits

OBJECTIVE

This study investigated the involvement of α1- and β2-adrenergic receptors in skeletal muscle blood flow changes during variations in ETCO2.

METHODS

Forty Japanese White rabbits anesthetized with isoflurane were randomly allocated to 1 of 5 groups: phentolamine, metaproterenol, phenylephrine, butoxamine, and atropine. Heart rate (HR), systolic blood pressure (SBP), common carotid artery blood flow (CCBF), masseter muscle tissue blood flow (MBF), and quadriceps muscle tissue blood flow (QBF) were recorded and analyzed at 3 periods: (1) baseline, (2) during hypercapnia (phentolamine and metaproterenol groups) or hypocapnia (phenylephrine, butoxamine, and atropine groups), and (3) during or after receiving vasoactive agents.

RESULTS

MBF and QBF decreased during hypercapnia. The decrease in MBF was smaller than that in QBF. SBP and CCBF increased, while HR decreased. Both MBF and QBF recovered to their baseline levels after phentolamine administration. MBF became greater than its baseline level, while QBF did not fully recover after metaproterenol administration. MBF and QBF increased during hypocapnia. The increase rate in MBF was larger than that in QBF. HR, SBP, and CCBF did not change. Both MBF and QBF decreased to ∼90% to 95% of their baseline levels after phenylephrine or butoxamine administration. Atropine showed no effects on MBF and QBF.

CONCLUSION

These results suggest the skeletal muscle blood flow changes observed during hypercapnia and hypocapnia may mainly involve α1-adrenergic but not β2-adrenergic receptor activity.

Differential control of blood flow in masseter and biceps brachii muscles during stress

OBJECTIVE

The present study aimed to compare sympathetic hemodynamic effects in masticatory and limb muscles in response to different stressors.

DESIGN

Twelve healthy participants were subjected to a randomized series of stressors, including cold pressor test (CPT), mental arithmetic test, apnea, isometric handgrip (IHG) and post-handgrip muscle ischemia (PHGMI), while in the supine position. Spatially-resolved near-infrared spectroscopy was used to measure relative changes in blood volume and oxygenation (TOI) of the resting masseter and biceps muscles. Cardiac output, heart rate, and arterial blood pressure (ABP) were also monitored.

RESULTS

Except apnea, all tests increased ABP. Different response patterns were observed in the 2 muscles: TOI significantly increased during contralateral IHG (1.24 ± 1.17%) but markedly decreased during CPT (-4.84 ± 4.09%) and PHGMI (-6.65 ± 5.31%) in the biceps muscle, while exhibiting consistent increases in the masseter (1.88 ± 1.85%; 1.60 ± 1.75%; 1.06 ± 3.29%, respectively) (p < 0.05).

CONCLUSIONS

The results allow us to infer differential control of blood flow in head and limb muscles. In general, the masseter appears more prone to dilatation than the biceps, exhibiting opposite changes in response to painful stimuli (CPT and PHGMI). Several mechanisms may mediate this effect, including reduced sympathetic outflow to the extracranial vasculature of the head, generally exposed to lower hydrostatic loads than the rest of the body.

Effects of changes in end-tidal carbon dioxide tension on oral tissue blood flow and tissue oxygen tension during remifentanil infusion in rabbits

PURPOSE

The aim of this study was to investigate the effects of end-tidal carbon dioxide tension (ETCO₂) changes during remifentanil infusion on mandibular bone marrow tissue blood flow (BBF), masseter muscle tissue blood flow (MBF), mandibular bone marrow tissue oxygen tension (PbO₂) and masseter muscle tissue oxygen tension (PmO₂) in rabbits.

METHODS

Ten male tracheotomized Japan White rabbits were anesthetized and ventilated with sevoflurane. ETCO₂ was adjusted to 30 mmHg. After baseline measurement, CO₂ was added to the inhaled air, and ETCO₂ was increased to 40 and 60 mmHg. Heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), BBF, MBF, PbO₂, and PmO₂ were recorded with and without remifentanil infusion at 0.4 µg/kg/min.

RESULTS

Two-way repeated measures analysis of variance showed no interaction between ETCO₂ and remifentanil in all variables. Remifentanil infusion produced decreases in HR, SBP, MAP, BBF and MBF compared with those without remifentanil infusion, while it did not affect DBP, PbO₂ and PmO₂. Elevation of ETCO₂ from 30 to 60 mmHg produced decreases in HR and MBF, and increases in SBP, DBP, MAP and BBF, while it did not affect PbO₂ and PmO₂.

CONCLUSION

PbO₂ and PmO₂ remained unchanged despite changes in BBF and MBF during ETCO₂ change with or without remifentanil infusion.

Hemodynamic Changes with 1:1000 Epinephrine on Wrung-Out Pledgets Before and During Sinus Surgery

BACKGROUND

Intranasal topical 1:1000 epinephrine has been used safely and effectively for hemostasis during endoscopic sinus surgery (ESS). Prior studies assessing hemodynamic changes after intranasal topical epinephrine application have only used soaking wet cottonoid pledgets, and have only assessed for hemodynamic changes before any surgery being performed.

OBJECTIVE

The purposes of this study were to determine whether intranasal application of topical 1:1000 epinephrine with wrung-out cottonoid pledgets caused significant hemodynamic changes both before and during ESS, and whether it allowed for adequate hemostasis.

METHODS

A prospective evaluation of 30 patients with eosinophilic chronic rhinosinusitis with nasal polyps (CRSwNP) undergoing complete bilateral ESS was conducted. Heart rate, blood pressure (systolic, diastolic, and mean arterial pressure), and electrocardiography changes were recorded at 0, 1, 2, and 5-minute intervals after placing wrung-out epinephrine-saturated pledgets, both before and at the end of ESS. No submucosal epinephrine injections were performed. Estimated blood loss (EBL) and major intraoperative complications were recorded for all cases.

RESULTS

There were no significant hemodynamic changes or electrocardiographic abnormalities after placement of wrung-out epinephrine-soaked pledgets both before and after ESS. After bilateral ESS, there were actually mean decreases in heart rate and blood pressure parameters. Mean EBL was 75.8 ± 32.2 mL, and no major intraoperative complications occurred.

CONCLUSION

Intranasal application of topical 1:1000 epinephrine via wrung-out cottonoid pledgets was effective for intraoperative hemostasis, and did not cause clinically significant alterations in hemodynamic parameters or cardiovascular events, either before or during ESS in patients with CRSwNP.Level of Evidence: 4.