The Telluride YAP/TAZ and TEAD Workshop: A Small Meeting with a Big Impact.

Funding the research needed to advance our understanding of rare cancers is very challenging [...].

Epinephrine induces rapid deterioration in pulmonary oxygen exchange in intact, anesthetized rats: a flow and pulmonary capillary pressure-dependent phenomenon.

BACKGROUND: Previous studies indicate epinephrine adversely affects arterial oxygenation when administered in a rat model of local anesthetic overdose. The authors tested whether epinephrine alone exerts similar effects in the intact animal. METHODS: Anesthetized rats received a single intravenous injection of epinephrine (25, 50, or 100 mcg/kg); matched cohorts were pretreated with phentolamine (100 mcg/kg); n = 5 for each of the six treatment groups. Arterial pressure and blood gases were measured at baseline, 1 and 10 min after epinephrine administration. Pulmonary capillary pressures during epinephrine infusion with normal and increased flows were measured in an isolated lung preparation. RESULTS: Epinephrine injection in the intact animal caused hypoxemia, hypercapnia, and acidosis at all doses. Arterial oxygen tension was reduced within 1 min of injection. Hyperlactatemia occurred by 10 min after 50 and 100 mcg/kg. Rate pressure product was decreased by 10 min after 100 mcg/kg epinephrine. Pretreatment with phentolamine attenuated these effects except at 100 mcg/kg epinephrine. In the isolated lung preparation, epinephrine in combination with increased pulmonary flow increased pulmonary capillary pressure and lung water. CONCLUSIONS: Bolus injection of epinephrine in the intact, anesthetized rat impairs pulmonary oxygen exchange within 1 min of treatment. Effects were blunted by α-adrenergic receptor blockade. Edema occurred in the isolated lung above a threshold pulmonary capillary pressure when epinephrine treatment was coupled with an increase in pulmonary flow. These results potentially argue against using traditional doses of epinephrine for resuscitation, particularly in the anesthetized patient.

Nanomedicines for chronic non-infectious arthritis: the clinician's perspective.

Rheumatoid arthritis (RA) and osteoarthritis (OA) are prevalent chronic health conditions. However, despite recent advances in medical therapeutics, their treatment still represents an unmet medical need because of safety and efficacy concerns with currently prescribed drugs. Accordingly, there is an urgent need to develop and test new drugs for RA and OA that selectively target inflamed joints thereby mitigating damage to healthy tissues. Conceivably, biocompatible, biodegradable, disease-modifying antirheumatic nanomedicines (DMARNs) could represent a promising therapeutic approach for RA and OA. To this end, the unique physicochemical properties of drug-loaded nanocarriers coupled with pathophysiological characteristics of inflamed joints amplify bioavailability and bioactivity of DMARNs and promote their selective targeting to inflamed joints. This, in turn, minimizes the amount of drug required to control articular inflammation and circumvents collateral damage to healthy tissues. Thus, nanomedicine could provide selective control both in space and time of the inflammatory process in affected joints. However, bringing safe and efficacious DMARNs for RA and OA to the marketplace is challenging because regulatory agencies have no official definition of nanotechnology, and rules and definitions for nanomedicines are still being developed. Although existing toxicology tests may be adequate for most DMARNs, as new toxicity risks and adverse health effects derived from novel nanomaterials with intended use in humans are identified, additional toxicology tests would be required. Hence, we propose that detailed pre-clinical in vivo safety assessment of promising DMARNs leads for RA and OA, including risks to the general population, must be conducted before clinical trials begin.

Pioglitazone attenuates acute cocaine toxicity in rat isolated heart: potential protection by metabolic modulation.

BACKGROUND: The authors tested whether cocaine depresses mitochondrial acylcarnitine exchange and if a drug that enhances glucose metabolism could protect against cocaine-induced cardiac dysfunction. METHODS: Oxygen consumption with and without cocaine was compared in rat cardiac mitochondria using octanoylcarnitine (lipid) or pyruvate (nonlipid) substrates. Isolated hearts from rats with or without a pioglitazone-supplemented diet were exposed to cocaine. RESULTS: The 0.5 mM cocaine inhibited respiration supported by octanoylcarnitine (82 ± 10.4 and 45.7 ± 4.24 ngatomO min⁻¹ · mg⁻¹ · protein ± SEM, for control and cocaine treatment, respectively; P < 0.02) but not pyruvate-supported respiration (281 ± 12.5 and 267 ± 12.7 ngatomO min⁻¹ · mg⁻¹ · protein ± SEM; P = 0.45). Cocaine altered contractility, lusitropy, coronary resistance, and lactate production in isolated heart. These effects were each blunted in pioglitazone-treated hearts. The pioglitazone diet attenuated the drop in the rate-pressure product (P = 0.002), cocaine-induced diastolic dysfunction (P = 0.04), and myocardial vascular resistance (P = 0.05) compared with that of controls. Lactate production was higher in pretreated hearts (P = 0.008) and in ventricular myocytes cultured with pioglitazone (P = 0.0001). CONCLUSIONS: Cocaine inhibited octanoylcarnitine-supported mitochondrial respiration. A pioglitazone diet significantly attenuated the effects of cocaine on isolated heart. The authors postulate that inhibition of acylcarnitine exchange could contribute to cocaine-induced cardiac dysfunction and that metabolic modulation warrants additional study.

American Society of Regional Anesthesia and Pain Medicine Local Anesthetic Systemic Toxicity checklist: 2020 version.

The American Society of Regional Anesthesia and Pain Medicine (ASRA) periodically updates its practice advisories and associated cognitive aids. The 2020 version of the ASRA Local Anesthetic Systemic Toxicity checklist was created in response to user feedback, simulation studies and advances in medical knowledge. This report presents the 2020 version and discusses the rationale for its update.

Lipid emulsion is superior to vasopressin in a rodent model of resuscitation from toxin-induced cardiac arrest.

OBJECTIVES: Lipid emulsion infusion is an emerging antidotal therapy for toxin-induced cardiac arrest. To compare the efficacy of resuscitation from bupivacaine-induced asystole using lipid emulsion infusion vs. vasopressin, alone and with epinephrine. DESIGN: Prospective, randomized, animal study. SETTING: University research laboratory. SUBJECTS: Adult, male Sprague-Dawley rats. INTERVENTIONS: Instrumented rats were given an intravenous bolus of 20 mg/kg bupivacaine to induce asystole (zero time). Rats (n = 6 for all groups) were ventilated with 100% oxygen, given chest compressions, and randomized to receive 30% lipid emulsion (L, 5 mL/kg bolus then 1.0 mL/kg/min infusion) and vasopressin 0.4 U/kg bolus alone (V) or combined with epinephrine, 30 microg/kg (V + E); boluses (L, V, or V + E) were repeated at 2.5 and 5 minutes for a rate-pressure product (RPP) less than 20% baseline. MEASUREMENTS AND MAIN RESULTS: The arterial blood pressure and electrocardiogram were measured continuously for 10 minutes when blood was drawn for arterial blood gas analysis, lactate content, and central venous oxygen saturation (ScvpO2). Hemodynamic parameters of the L group at 10 minutes (30,615 +/- 4782 mm Hg/min; 151 +/- 19.1 mm Hg; 197 +/- 8.6 min; RPP, systolic blood pressure and heart rate, respectively) exceeded those of the V group (5395 +/- 1310 mm Hg/min; 85.8 +/- 12 mm Hg; 61 +/- 10.8 min) and the V + E group (11,183 +/- 1857 mm Hg/min; 75.5 +/- 12.9 min, RPP and heart rate, respectively; systolic blood pressure was not different). Metrics indicated better tissue perfusion in the L group (7.24 +/- 0.02; 83% +/- 3.5%; 2.2 +/- 0.36 mmol/L; pH, ScvpO2, lactate, respectively) than V (7.13 +/- 0.02; 29.9% +/- 4.4%; 7.5 +/- 0.6 mmol/L) and V + E groups (7.07 +/- 0.03; 26.2% +/- 8.9%; 7.7 +/- 1 mmol/L). Wet-to-dry lung ratios in V (8.3 +/- 0.6) and V + E (8.7 +/- 0.2) were greater than that in the L group (6.2 +/- 05) (mean +/- sem; p < 0.05 for all shown results). CONCLUSIONS: Lipid emulsion in this rat model provides superior hemodynamic and metabolic recovery from bupivacaine-induced cardiac arrest than do vasopressors. Systolic pressure was not a useful metric in the vasopressor groups. Vasopressin was associated with adverse outcomes.

Epinephrine impairs lipid resuscitation from bupivacaine overdose: a threshold effect.

BACKGROUND: Lipid emulsion infusion reverses local anesthetic-induced cardiac toxicity, but the effect of adding epinephrine has not been studied. We compared escalating doses of epinephrine on recovery with lipid infusion in a rat model of bupivacaine overdose. METHODS: Rats anesthetized with isoflurane received an IV bolus of 20 mg/kg bupivacaine, producing asystole (zero time) in all animals. Ventilation (100% oxygen) and chest compressions were started immediately, and at 3 min the rats received one of six IV treatments (n = 5 for all groups): 5 ml/kg saline followed by infusion for 2 min at 1.0 ml x kg x min, and a second 5 ml/kg bolus at 5 min; or the same bolus and infusion treatment using 30% lipid emulsion plus a single injection of epinephrine at one of five doses: 0 (lipid control), 1, 2.5, 10, or 25 mcg/kg. An electrocardiogram and arterial pressure were monitored continuously, and arterial blood gas was measured at 7.5 and 15 min. RESULTS: Epinephrine improved initial return of spontaneous circulation (rate-pressure product > 30% baseline) but only 3 of 5 rats at 10 mcg/kg and 1 of 5 rats at 25 mcg/kg sustained return of spontaneous circulation by 15 min. Lipid alone resulted in slower but more sustained recovery. Epinephrine doses above a threshold near 10 mcg/kg increased lactate, worsened acidosis, and resulted in poor recovery at 15 min, as compared with lipid controls. There was tight correlation of epinephrine dose to serum lactate at 15 min. CONCLUSIONS: Epinephrine over a threshold dose near 10 mcg/kg impairs lipid resuscitation from bupivacaine overdose, possibly by inducing hyperlactatemia.

Lipid resuscitation for local anesthetic toxicity: is it really lifesaving?

PURPOSE OF REVIEW: Laboratory studies and clinical reports have led to the acceptance of lipid emulsion as an effective treatment of local anesthetic-induced cardiac arrest. This review discusses subsequent clinical reports, relevant laboratory studies and topics for further research. RECENT FINDINGS: Case reports have confirmed the efficacy of lipid resuscitation for local anesthetic systemic toxicity. Furthermore, lipid emulsion has been used with apparent success early in the spectrum of local anesthetic systemic toxicity to preempt cardiac arrest. The role of lipid emulsion has expanded to treatment of cardiac toxicity due to other lipophilic drugs. This appears to have an acceptable safety profile, although elevated amylase has been reported. Laboratory investigations in animals suggest that concomitant hypoxemia hinders resuscitation attempts, and that epinephrine and vasopressin are more likely to be associated with poor outcomes than lipid. SUMMARY: Lipid emulsion infusion appears to be an effective treatment for cardiac toxicity induced by lipophilic medications. Given the difficulties of performing clinical trials, further laboratory investigation and clinical correlation are needed to better define its role in resuscitation.

Local Anesthetic Systemic Toxicity: A Narrative Literature Review and Clinical Update on Prevention, Diagnosis, and Management.

BACKGROUND: The objective of this narrative review of local anesthetic systemic toxicity is to provide an update on its prevention, diagnosis, and management. METHODS: The authors used a MEDLINE search of human studies, animal studies, and case reports and summarize findings following the American Society of Regional Anesthesia and Pain Medicine practice advisories on local anesthetic systemic toxicity. RESULTS: Between March of 2014 and November of 2016, there were 47 cases of systemic toxicity described. Twenty-two patients (47 percent) were treated with intravenous lipid emulsion and two patients (4.3 percent) died. Seizures were the most common presentation. The spectrum of presenting neurologic and cardiovascular symptoms and signs are broad and can be obscured by perioperative processes. Local anesthetic type, dosage, and volume; site of injection; and patient comorbidities influence the rate of absorption from the site of injection and biodegradation of local anesthetics. Consider discussing appropriate dosages as a component of the surgical "time-out." A large-volume depot of dilute local anesthetic can take hours before reaching peak plasma levels. Oxygenation, ventilation, and advanced cardiac life support are the first priorities in treatment. Lipid emulsion therapy should be given at the first sign of serious systemic toxicity with an initial bolus dose of 100 ml for adults weighing greater than 70 kg and 1.5 ml/kg for adults weighing less than 70 kg or for children. CONCLUSION: All physicians who administer local anesthetics should be educated regarding the nature of systemic toxicity and contemporary management algorithms that include lipid emulsion therapy.

Resuscitation with lipid versus epinephrine in a rat model of bupivacaine overdose.

BACKGROUND: Lipid emulsion infusion reverses cardiovascular compromise due to local anesthetic overdose in laboratory and clinical settings. The authors compared resuscitation with lipid, epinephrine, and saline control in a rat model of bupivacaine-induced cardiac toxicity to determine whether lipid provides a benefit over epinephrine. METHODS: Bupivacaine, 20 mg/kg, was infused in rats anesthetized with isoflurane, producing asystole in all subjects. Ventilation with 100% oxygen and chest compressions were begun immediately, along with intravenous treatment with 30% lipid emulsion or saline (5-ml/kg bolus plus continuous infusion at 0.5 ml . kg . min) or epinephrine (30 microg/kg). Chest compressions were continued and boluses were repeated at 2.5 and 5 min until the native rate-pressure product was greater than 20% baseline. Electrocardiogram and arterial pressure were monitored continuously and at 10 min, arterial blood gas, central venous oxygen saturation, and blood lactate were measured. Effect size (Cohen d) was determined for comparisons at 10 min. RESULTS: Lipid infusion resulted in higher rate-pressure product (P < 0.001, d = 3.84), pH (P < 0.01, d = 3.78), arterial oxygen tension (P < 0.05, d = 2.8), and central venous oxygen saturation (P < 0.001, d = 4.9) at 10 min than did epinephrine. Epinephrine treatment caused higher lactate (P < 0.01, d = 1.48), persistent ventricular ectopy in all subjects, pulmonary edema in four of five rats, hypoxemia, and a mixed metabolic and respiratory acidosis by 10 min. CONCLUSIONS: Hemodynamic and metabolic metrics during resuscitation with lipid surpassed those with epinephrine, which were no better than those seen in the saline control group. Further studies are required to optimize the clinical management of systemic local anesthetic toxicity.

Use of lipid emulsion in the resuscitation of a patient with prolonged cardiovascular collapse after overdose of bupropion and lamotrigine.

Animal studies show efficacy of intravenous lipid emulsion in the treatment of severe cardiotoxicity associated with local anesthetics, clomipramine, and verapamil, possibly by trapping such lipophilic drugs in an expanded plasma lipid compartment ("lipid sink"). Recent case reports describe lipid infusion for the successful treatment of refractory cardiac arrest caused by parenteral administration of local anesthetics, but clinical evidence has been lacking for lipid's antidotal efficacy on toxicity caused by ingested medications. A 17-year-old girl developed seizure activity and cardiovascular collapse after intentional ingestion of up to 7.95 g of bupropion and 4 g of lamotrigine. Standard cardiopulmonary resuscitation for 70 minutes was unsuccessful in restoring sustained circulation. A 100-mL intravenous bolus of 20% lipid emulsion was then administered, and after 1 minute an effective sustained pulse was observed. The patient subsequently manifested significant acute lung injury but had rapid improvement in cardiovascular status and recovered, with near-normal neurologic function. Serum bupropion levels before and after lipid infusion paralleled triglyceride levels. This patient developed cardiovascular collapse because of intentional, oral overdose of bupropion and lamotrigine that was initially refractory to standard resuscitation measures. An infusion of lipid emulsion was followed rapidly by restoration of effective circulation. Toxicologic studies are consistent with the lipid sink theory of antidotal efficacy.

Metabolic context affects hemodynamic response to bupivacaine in the isolated rat heart.

Previous studies have demonstrated that the local anesthetic bupivacaine selectively inhibits oxidative metabolism of fatty acids in isolated cardiac mitochondria. In the present investigation, we compare the development of bupivacaine cardiotoxicity during fatty acid and carbohydrate metabolism. Hearts from adult male Sprague-Dawley rats were excised and retrograde perfused with a solution containing fatty acid (oleate or octanoate) or carbohydrate substrates for cardiac metabolism. An infusion of bupivacaine was initiated and sustained until asystole, after which full cardiac recovery was allowed. During fatty acid metabolism, substantially lower bupivacaine doses induced both arrhythmia (60.4+/-11.5 microg oleate and 106.8+/-14.8 octanoate versus 153.4+/-21.4 carbohydrate; P<0.05) and asystole (121.0+/-30.1 microg and 171.5+/-20.2 versus 344.7+/-34.6; P<0.001). Dose-response analysis revealed significantly increased sensitivity to bupivacaine toxicity during fatty acid metabolism, indicated by lower V50 doses for both heart rate (70.6+/-5.6 microg oleate and 122.3+/-6.2 octanoate versus 152.6+/-8.6) and rate-pressure product (63.4+/-5.1 microg and 133.7+/-7.9 versus 165.1+/-12.2). Time to recovery following bupivacaine exposure was elevated in the fatty acid group (24.3+/-2.0 s versus 15.8+/-3.1; P<0.04). Fatty acid metabolism was shown to predispose the isolated heart to bupivacaine toxicity, confirming that the local anesthetic exerts specific effects on lipid processes in cardiomyocytes.

Bupivacaine, but not lidocaine, disrupts cardiolipin-containing small biomimetic unilamellar liposomes.

Inadvertent intravenous administration of bupivacaine, unlike that of lidocaine, is associated with significant cardiotoxicity. However, the mechanism(s) underlying this phenomenon is uncertain. High concentrations of cardiolipin, an anionic phospholipid, are found in the mitochondria membrane of cardiomyocytes. We hypothesized that bupivacaine, but not lidocaine, interacts avidly with cardiolipin in the mitochondria membrane of cardiomyocytes and alters its integrity thereby accounting, in part, for cardiotoxicity. Accordingly, the purpose of this study was to begin to address this issue by determining the effects of bupivacaine and lidocaine on permeability of cardiolipin-containing biomimetic small unilamellar liposomes. We found that bupivacaine, but not lidocaine, elicited a significant, concentration-dependent increase in carboxyfluorescein release from cardiolipin-containing small unilamellar liposomes (size, 165nm) composed of egg yolk phosphatidylcholine and cholesterol (p<0.05). Both drugs had no significant effects on carboxyfluorescein release from liposomes devoid of cardiolipin (p>0.5). Collectively, these data indicate that bupivacaine, but not lidocaine, interacts avidly and selectively with biomimetic small unilamellar liposomes containing cardiolipin and disrupts their integrity. We suggest that these interactions underlie, in part, bupivacaine-induced cardiotoxicity.