Vascular Dilation, Tachycardia, and Increased Inotropy Occur Sequentially with Increasing Epinephrine Dose Rate, Plasma and Myocardial Concentrations, and cAMP

Comparing Hemorrhage in Human Physiology Simulation Tools: How They Compare With Expected Human Physiology and Each Other

INTRODUCTION

Several different whole-body physiology simulation tools (PST) using modeling techniques are now available with potential use for healthcare simulation, but these novel technologies lack objective analysis from an independent organization.

METHODS

We identified BioGears, HumMod, and Muse as 3 PSTs that met our requirements for testing. We ran mild, moderate, and severe hemorrhage scenarios on each PST and collected outputs for comparison with each other and published human physiology data.

RESULTS

All PSTs tested followed the expected tachycardic and hypotensive response to hemorrhage for all levels of severity with variable qualitative patterns. Complete data for analysis were not available in all PSTs for urine output, stroke volume, blood volume, hemoglobin, and serum epinephrine concentration, but the partial findings are discussed in detail. We determined the predicted time to reach hemorrhage shock based on the hemorrhage guidelines and compared this with time to cardiovascular collapse from each PST. Overall, the differences from known human physiology were much larger than expected before testing and trends show HumMod with the smallest difference for severe (-6.25%) and moderate (-1.42%) and Muse with the smallest difference for mild hemorrhage (27.9%). BioGears demonstrated the largest differences in all classifications of severity.

CONCLUSIONS

Our analysis of currently available whole-body PSTs provides insight into the novel, evolving field. We hope our efforts shed light to a wider audience to the exciting developments and uses of mathematical modeling for whole-body simulation and the potential for integration into healthcare simulation for medical education.

Keeping the Finger on the Pulse: Cardiac Arrhythmias in Hand Surgery Using Local Anesthesia with Adrenaline

BACKGROUND

The wide-awake local anesthesia no tourniquet (WALANT) technique in hand surgery is gaining popularity. The authors aimed to prospectively analyze the frequency and type of arrhythmias in patients undergoing hand surgery under local anesthesia and to examine whether the addition of adrenaline affects their incidence.

METHODS

Adult patients undergoing hand surgery under local anesthesia were randomized into two groups: group 1, local anesthesia with lidocaine and tourniquet; and group 2, local anesthesia with lidocaine and adrenaline (WALANT). Patients with a history of arrhythmias were excluded. Patients were connected to Holter electrocardiographic monitoring before surgery and up until discharge. The records were blindly compared between the groups regarding types of arrhythmias, and frequency and timing relative to injection and tourniquet inflation.

RESULTS

One hundred two patients were included between August of 2018 and August of 2019 (age, 59.7 ± 13.6 years; 71 percent women; 51 in each group). No major arrhythmia (ventricular tachycardia, ventricular fibrillation, atrial fibrillation) or arrhythmia-related symptoms were recorded for either group. Minor arrhythmias (including atrial premature beats, ventricular premature beats, and atrial tachycardia) were recorded in 68 patients (66.6 percent), with no statistical difference between the groups. There were three patients with minor arrhythmias during inflation of the tourniquet. Patients in the adrenaline group had 2 percent sinus tachycardia during injection and 4 percent asymptomatic bradyarrhythmias. These findings do not require any further treatment.

CONCLUSIONS

The authors' results show that hand operations using WALANT technique in patients with no history of arrhythmia are safe and are not arrhythmogenic; therefore, there is no need for routine perioperative continuous electrocardiographic monitoring.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, II.

Approximate Weight of 1:1000 Topical Epinephrine on Wrung-Out Epinephrine-Soaked Pledgets

OBJECTIVE

Topical 1:1000 epinephrine solution is commonly applied intranasally with cottonoid pledgets in endoscopic sinonasal surgery for local vasoconstriction and hemostasis. Pledgets are typically submerged in epinephrine solution and applied without measurement. Hemodynamic complications have been reported when pledgets have been saturated and not wrung out. The amount of epinephrine absorbed per pledget has not been studied methodically. The purpose of this study was to determine the amount of topical 1:1000 epinephrine remaining on a cottonoid pledget after wringing out the pledget, to simulate intraoperative application.

STUDY DESIGN

Cohort study.

SETTING

Tertiary care center.

SUBJECTS AND METHODS

Sixty 0.5-in × 3-in cottonoid pledgets were submerged in canisters filled with 1:1000 epinephrine solution (1 mg/mL). Weights of the epinephrine-filled canisters were measured before submerging the pledgets and then after removing and wringing out the pledgets. Measurements were recorded for each pledget after being submerged for 0, 1, and 5 minutes and then wrung out. Mean weights were calculated and compared between the submersion durations.

RESULTS

The mean overall weight of epinephrine on a wrung-out pledget was 0.931 mg. Mean weights of epinephrine absorbed onto wrung-out pledgets after submersion for 0, 1, and 5 minutes were 0.914, 0.913, and 0.967 mg, respectively. There were no significant differences in weights based on submersion duration (P = .296).

CONCLUSION

Approximately 1 mg of epinephrine was absorbed onto 0.5-in × 3-in cottonoid pledgets when pledgets were wrung out after being submerged in 1:1000 epinephrine, whether being removed from solution immediately or after up to 5 minutes.

Human Errors and Adverse Hemodynamic Events Related to "Push Dose Pressors" in the Emergency Department

BACKGROUND

Though the use of small bolus doses of vasopressors, termed "push dose pressors," has become common in emergency medicine, data examining this practice are scant. Push dose pressors frequently involve bedside dilution, which may result in errors and adverse events. The objective of this study was to assess for instances of human error and adverse hemodynamic events during push dose pressor use in the emergency department.

METHODS

This was a structured chart and video review of all patients age ≥ 16 years undergoing resuscitation and receiving push dose pressors from a single center from January 2010 to November 2017. Push dose pressors were defined as intended intravenous boluses of phenylephrine (any dose) or epinephrine (≤ 100 mcg).

RESULTS

A total of 249 patients were analyzed. Median age was 60 years (range, 16-97), 58% were male, 49% survived to discharge. Median initial epinephrine dose was 20 mcg (n = 139, IQR 10-100, range 1-100); median phenylephrine dose was 100 mcg (n = 110, IQR 100-100, range 25-10,000). Adverse hemodynamic events occurred in 98 patients (39%); 30 in the phenylephrine group (27%; 95% CI, 19-36%), and 68 in the epinephrine group (50%; 95% CI, 41-58%). Human errors were observed in 47 patients (19%), including 7 patients (3%) experiencing dosing errors (all overdoses; range, 2.5- to 100-fold) and 43 patients (17%) with a documentation error. Only one dosing error occurred when a pharmacist was present.

CONCLUSIONS

Human errors and adverse hemodynamic events were common with the use of push dose pressors in the emergency department. Adverse hemodynamic events were more common than in previous studies. Future research should determine if push dose pressors improve outcomes and if so, how to safely implement them into practice.

Synergy between sacubitril and valsartan leads to hemodynamic, antifibrotic, and exercise tolerance benefits in rats with preexisting heart failure

Simultaneous neprilysin inhibition (NEPi) and angiotensin receptor blockade (ARB) with sacubitril/valsartan improves cardiac function and exercise tolerance in patients with heart failure. However, it is not known whether these therapeutic benefits are primarily due to NEPi with sacubitril or ARB with valsartan or their combination. Therefore, the aim of the present study was to investigate the potential contribution of sacubitril and valsartan to the benefits of the combination therapy on left ventricular (LV) function and exercise tolerance. Heart failure was induced by volume overload via partial disruption of the aortic valve in rats. Therapy began 4 wk after valve disruption and lasted through 8 wk. Drugs were administered daily via oral gavage [sacubitril/valsartan (68 mg/kg), valsartan (31 mg/kg), and sacubitril (31 mg/kg)]. Hemodynamic assessments were conducted using Millar technology, and an exercise tolerance test was conducted using a rodent treadmill. Therapy with sacubitril/valsartan improved load-dependent indexes of LV contractility (dP/d t_max) and relaxation (dP/d t_min), exercise tolerance, and mitigated myocardial fibrosis, whereas monotherapies with valsartan, or sacubitril did not. Both sacubitril/valsartan and valsartan similarly improved a load-independent index of contractility [slope of the end-systolic pressure-volume relationship ( E_es)]. Sacubitril did not improve E_es. First, synergy of NEPi with sacubitril and ARB with valsartan leads to the improvement of load-dependent LV contractility and relaxation, exercise tolerance, and reduction of myocardial collagen content. Second, the improvement in load-independent LV contractility with sacubitril/valsartan appears to be solely due to ARB with valsartan constituent. NEW & NOTEWORTHY Our data suggest the following explanation for the effects of sacubitril/valsartan: 1) synergy of sacubitril and valsartan leads to the improvement of load-dependent left ventricular contractility and relaxation, exercise tolerance, and reduction of myocardial fibrosis and 2) improvement in load-independent left ventricular contractility is solely due to the valsartan constituent. The findings offer a better understanding of the outcomes observed in clinical studies and might facilitate the continuing development of the next generations of angiotensin receptor neprilysin inhibitors.

A Novel Paradigm for Sacubitril/Valsartan: Beta-Endorphin Elevation as a Contributor to Exercise Tolerance Improvement in Rats With Preexisting Heart Failure Induced by Pressure Overload

BACKGROUND

Simultaneous angiotensin receptor (AT1) blockade and neprilysin inhibition with the use of sacubitril/valsartan has been recently approved to treat patients with heart failure (HF). Therapeutic benefits of this therapy have been attributed to natriuretic peptide elevation and AT1 receptor blockade. However, that pharmacologic picture may not be complete. The aims of this study were to investigate the pharmacology of sacubitril/valsartan compared with sacubitril and valsartan alone and to examine their impact on peptides up-regulated by neprilysin inhibition, such as beta-endorphin.

METHODS AND RESULTS

An HF model was induced by pressure overload via constriction of the suprarenal abdominal aorta in rats. Sacubitril/valsartan (68 mg/kg), valsartan (31 mg/kg), sacubitril (31 mg/kg), or placebo was administered by daily oral gavage (starting 4 weeks after pressure overload onset and continued for 4 additional weeks; n = 8 in each group). Exercise tolerance testing was conducted using a rodent treadmill and hemodynamic assessments were conducted under anesthesia with the use of Millar left ventricular (LV) conductance technology. Pressure overload led to exercise intolerance by 4 weeks and to hypertension and LV dysfunction and remodeling by 8 weeks. Both sacubitril/valsartan and sacubitril elevated beta-endorphin levels, by 40% and 54%, respectively, and improved exercise tolerance, by 93% and 112%, whereas valsartan did not. Indices of LV dysfunction persisted with the use of sacubitril/valsartan and valsartan therapies and even deteriorated in sacubitril group.

CONCLUSIONS

When added to valsartan, sacubitril increases beta-endorphin concentrations and improves exercise tolerance. These data suggest beta-endorphin elevation as a potential mechanism of action leading to improvement in exercise tolerance that is seen with sacubitril/valsartan. This therapeutic benefit is potentially independent from LV function.

Epinephrine stimulates CXCL1 IL-1α, IL-6 secretion in isolated mouse limb muscle

Catecholamines stimulate interleukin‐6 (IL‐6) secretion in skeletal muscles. However, whether other cytokines are secreted is currently unknown. Skeletal muscle ex vivo preparations commonly used to study cytokine secretion have dealt with limitations including auto‐oxidation of catecholamines. The use of metal chelators could be an alternative to avoid auto‐oxidation and allow catecholamines to be used at physiological doses. We exposed isolated soleus muscles to 1 or 100 ng/mL epinephrine (EPI) and collected bath samples at 1 and 2 h for multiplex cytokine analysis. Keratinocyte chemoattractant (CXCL1), IL‐6, and IL‐1α were significantly elevated by 100 ng/mL exposure, but not by 1 ng/mL (median [CXCL1] (2 h) = 83 pg/mL; [IL‐6] = 19 pg/mL; IL‐1α = 7.5 pg/mL). CXCL1 and IL‐6 were highly correlated in each sample (P = 0.0001). A second experiment combined the metal chelator, deferoxamine mesylate (DFO), to prevent EPI autoxidation, with 2 ng/mL EPI and 10.5 ng/mL norepinephrine (NOREPI) to mimic peak exercise. Unexpectedly, DFO alone stimulated both IL‐6 and CXCL1 secretion, but together with EPI and NOREPI had no additional effects. Stimulation of cytokine secretory responses from skeletal muscle cells in response to DFO thus precludes its use as a chelating agent in ex vivo models. In conclusion, 100 ng/mL EPI stimulates a robust secretory CXCL1 response, which together with IL‐6 and IL‐1α, may constitute an adrenal‐muscle endocrine response system.

The reciprocal interaction of sympathetic nervous system and cAMP-PKA-NF-kB pathway in immune suppression after experimental stroke

BACKGROUND

Sympathetic nervous system(SNS) is involved in the mechanism of immune suppression after stroke. Furthermore, as the pro-inflammatory effect of nuclear factor kappa B(NF-kB) is inhibited after stroke, which is regulated by cyclic adenosine monophosphate(cAMP) and proteinkinase A(PKA). The cAMP-PKA-NF-kB pathway might play an important role in noradrenergic-mediated immune dysfunction.

AIM

The purpose of our research is to analyze how SNS interfere with the immune system after acute stroke and the underlying mechanism of cAMP-PKA-NF-kB pathway in regulating the inflammation.

METHODS

32 healthy male Sprague-Dawley rats were divided into 4 groups equally and randomly (1) Sham operation group; (2) middle cerebral artery occlusion; (MCAO) control group; (3) propranolol MCAO group; (4) isopropylarterenol sham group. 72h later after MCAO or sham operation, tumor necrosis factor-α(TNF-α)and interleukine-10(IL-10) in serum as well as cAMP, PKA and NF-kB in spleen cells were tested.

RESULTS

TNF-α decreased while IL-10 increased in serum after acute ischemia stroke (p<0.05). Meanwhile, the levels of cAMP and PKA in spleen both increased in MCAO model while the expression of NF-kB was inhibited (p<0.05). When propranolol was used to inhibit SNS, all of the results reversed (p<0.05). But the reversed results were still significantly different from the sham operation group (p<0.05). Isopropylarterenol administrated rats appeared the same trend as MCAO group when compared to the sham operation group (p<0.05). However, the differences still existed (p<0.05).

CONCLUSION

On account of the SNS activation after stroke, epinephrine activates the expression of cAMP, which further increases the level of PKA. Therefore, the level of nuclear factor NF-kB is down-regulated. Since the pro-inflammatory effect of NF-kB slacked, the immune system may be inhibited after stroke.