Insulin improves survival in a canine model of acute beta-blocker toxicity

Hopeful News for Physicians Who Involved in the Treatment of Critical Aluminum Phosphide (Rice Pill) Poisoning Patients

Introduction

Aluminum phosphide (rice tablet) was first introduced as a pesticide in India. Rice tablets are commonly used in Iran due to their high efficacy against rodents and insects, low cost, and availability. Aluminum phosphide is a lethal poison without antidote and causes cardiocirculatory collapse and has negative inotropic cardiac effect. Human and animal studies showed that high dose insulin had positive cardiac inotropic effects. GIK (glucose, insulin, and potassium) assists heart uptake of carbohydrates that are the major fuel substrate of the myocard muscle under stressed conditions and leading to correction of acidosis, increased myocardial contractility, and peripheral vascular resistance. Case Presentation. In this manuscript, a young woman with aluminum phosphide poisoning was described to have presented with hypotension, hypoxemia, and severe metabolic acidosis. In contrast to our previous experiences that approximately all rice tablet poisoning patients with shock were dead despite full conservative treatment, this patient miraculously was saved with high dose intravenous regular insulin infusion and was discharged from the hospital with good condition and without any complications.

Conclusion

Rice tablet poisoning has high fatality rate, and to date, no antidote is available. GIK is suggested as a potential life saving treatment for critical rice tablet poisoning patients with symptoms and signs of shock.

Treatment of critical aluminum phosphide (rice tablet) poisoning with high-dose insulin: a case report

BACKGROUND

Aluminum phosphide (rice tablet) is a highly efficient agent for preserving grains against rodents and insects. It accounts for a large number of poisoning cases. Aluminum phosphide poisoning has a high mortality rate of about 90%, and to date, no antidote is available. It releases phosphine gas after exposure to moisture, and this reaction is catalyzed by the acidity of the stomach. Phosphine is then absorbed throughout the respiratory or gastrointestinal tracts and causes toxicity through inhibition of cytochrome c oxidase and formation of highly reactive free radicals. Treatment of patients with aluminum phosphide poisoning is supportive, including mechanical ventilation and vasopressors. The usage of infusion of glucose-insulin-potassium in rice tablet poisoning has been suggested, after its positive beneficial cardiac inotropic effects in patients with beta-blocker and calcium channel blocker poisoning.

CASE PRESENTATION

We report the case of a 30-year-old Iranian woman with critical aluminum phosphide poisoning, presented with hypotension and other signs of shock and severe metabolic acidosis, successfully treated with high-dose regular insulin and hypertonic dextrose and discharged from hospital in good condition. In contrast to our previous experiences, in which nearly all patients with critical aluminum phosphide poisoning died, this patient was saved with glucose-insulin-potassium.

CONCLUSION

Aluminum phosphide poisoning has a high mortality rate, and to date, no antidote is available. Administration of high-dose intravenous regular insulin and dextrose is suggested as a potential life-saving treatment for patients with critical aluminum phosphide poisoning.

Hyperinsulinemia/euglycemia and intravenous lipid emulsion therapy for the management of severe amlodipine toxicosis in a cat

Calcium-channel blockers (CCBs) are widely used in people and animals. Overdose can result in cardiovascular collapse and death. Hyperinsulinemia/euglycemia therapy (HIET) and intralipid therapy (ILT) are reported treatment options in people. This is the first report describing HIET and ILT as treatments for amlodipine toxicosis in a cat.

[Cardiac arrest under special circumstances]

These guidelines of the European Resuscitation Council (ERC) Cardiac Arrest under Special Circumstances are based on the 2020 International Consensus on Cardiopulmonary Resuscitation Science with Treatment Recommendations. This section provides guidelines on the modifications required for basic and advanced life support for the prevention and treatment of cardiac arrest under special circumstances; in particular, specific causes (hypoxia, trauma, anaphylaxis, sepsis, hypo-/hyperkalaemia and other electrolyte disorders, hypothermia, avalanche, hyperthermia and malignant hyperthermia, pulmonary embolism, coronary thrombosis, cardiac tamponade, tension pneumothorax, toxic agents), specific settings (operating room, cardiac surgery, cardiac catheterization laboratory, dialysis unit, dental clinics, transportation [in-flight, cruise ships], sport, drowning, mass casualty incidents), and specific patient groups (asthma and chronic obstructive pulmonary disease, neurological disease, morbid obesity, pregnancy).

European Resuscitation Council Guidelines 2021: Cardiac arrest in special circumstances

These European Resuscitation Council (ERC) Cardiac Arrest in Special Circumstances guidelines are based on the 2020 International Consensus on Cardiopulmonary Resuscitation Science with Treatment Recommendations. This section provides guidelines on the modifications required to basic and advanced life support for the prevention and treatment of cardiac arrest in special circumstances; specifically special causes (hypoxia, trauma, anaphylaxis, sepsis, hypo/hyperkalaemia and other electrolyte disorders, hypothermia, avalanche, hyperthermia and malignant hyperthermia, pulmonary embolism, coronary thrombosis, cardiac tamponade, tension pneumothorax, toxic agents), special settings (operating room, cardiac surgery, catheter laboratory, dialysis unit, dental clinics, transportation (in-flight, cruise ships), sport, drowning, mass casualty incidents), and special patient groups (asthma and COPD, neurological disease, obesity, pregnancy).

The Crashing Toxicology Patient

This article examines, using an organ-systems based approach, rapid diagnosis, resuscitation, and critical care management of the crashing poisoned patient in the emergency department. The topics discussed in this article include seizures and status epilepticus, respiratory failure, cardiovascular collapse and mechanical circulatory support, antidotes and drug-specific therapies, acute liver failure, and extracorporeal toxin removal.

Use of a Porcine Model to Evaluate the Risks and Benefits of Vasopressors in Propranolol Poisoning

INTRODUCTION

Vasopressors are a commonly used treatment in beta-blocker poisoning despite evidence they may be ineffective or harmful. The primary objective of the present study is to use previously collected data from two prior studies (high-dose insulin (HDI) versus vasopressin + epinephrine and a placebo-controlled HDI study) to compare survival between vasopressin + epinephrine and placebo. Secondary outcomes included a comparison with HDI as well as comparisons with hemodynamic parameters, including mean arterial pressure (MAP), cardiac output (CO), heart rate (HR), and systemic vascular resistance (SVR).

METHODS

Cardiogenic shock was induced in healthy pigs with a bolus of 0.5 mg/kg of intravenous propranolol followed by an infusion of 0.25 mg/kg/minute until the point of toxicity, defined as (0.75 × initial HR × initial MAP), at which point the infusion was reduced to 0.125 mg/kg/minute for 240 (vasopressin + epinephrine or HDI) or 360 minutes (placebo) or until death.

RESULTS

Survival was significantly lower in pigs receiving vasopressin + epinephrine (0%, 0/5) than in pigs receiving placebo (50%, 2/4) (p < 0.01). Survival was significantly higher with HDI compared with both groups (100%, 5/5) (p < 0.01). All vasopressin + epinephrine pigs died within 100 minutes after reaching toxicity. Over the course of the resuscitation, we observed a statistically significant steady decrease in CO and HR in the vasopressin + epinephrine group compared with placebo (p < 0.01). In contrast, we observed a statistically significant change in MAP and SVR that followed a parabolic arc, with MAP and SVR rising significantly initially in the vasopressin + epinephrine group then rapidly falling until death (p < 0.01).

CONCLUSIONS

Mortality was higher with vasopressors compared with placebo in this porcine model of propranolol poisoning. Further studies are warranted to define the optimal timing and role of vasopressors in beta-blocker poisoning.

Hyponatremia induced by hyperinsulinemia-euglycemia therapy

PURPOSE

A case of symptomatic hyponatremia induced by hyperinsulinemia-euglycemia (HIE) therapy is reported.

SUMMARY

A 59-year-old, 81.65-kg woman with hypertension, major depressive disorder, and anxiety arrived at a tertiary medical center 1.5 hours after an intentional overdose of oral amlodipine 200 mg, metoprolol tartrate 2,000 mg, and isosorbide mononitrate 1,200 mg. Upon arrival, her pulse was 63 beats/min and blood pressure was 106/56 mm Hg. The patient's blood pressure was refractory to fluids, calcium gluconate, and norepinephrine, resulting in initiation of HIE therapy. She had recurrent episodes of hypoglycemia, which required increases of the dextrose infusion and resulted in the patient receiving a total of 6.9 L of dextrose with free water. Seventeen hours into the hospitalization, the patient became obtunded due to hyponatremia (serum sodium concentration, 121 mmol/L). HIE therapy was discontinued, an infusion of 5% dextrose injection with sodium bicarbonate added was started, and a bolus of 3% sodium chloride was administered. Nine hours after the presentation of hyponatremia, the patient's serum sodium concentration normalized (137 mmol/L), and her symptoms resolved. The patient's blood pressure, pulse, and mental status continued to improve, and the patient was transferred out of the medical intensive care unit 41 hours after her arrival at the hospital.

CONCLUSION

A woman who overdosed on amlodipine, metoprolol tartrate, and isosorbide mononitrate was treated with HIE therapy and developed symptomatic hyponatremia. Hyponatremia resolved after administration of dextrose with sodium bicarbonate infusion and 3% sodium chloride infusion and cessation of HIE therapy.

A randomized controlled study comparing high-dose insulin to vasopressors or combination therapy in a porcine model of refractory propranolol-induced cardiogenic shock

Context: Although cerebral perfusion (CP) is preserved across a wide range of mean arterial pressures (MAP) through cerebral-vascular autoregulation, the relationship between MAP and CP in refractory poison-induced cardiogenic shock (PICS) has never been studied. We compared the effects of therapies used in PICS: high-dose insulin (HDI), HDI plus norepinephrine (NE), and vasopressors alone (NE plus epinephrine (Epi)) on cerebral tissue oxygenation (P_tO₂). Methods: Fifteen swine were randomized to either HDI, HDI + NE, or NE + Epi. All animals received a propranolol infusion using an established model of toxicity. At primary toxicity (P₁), defined as a 25% reduction in heart rate (HR) multiplied by MAP, the HDI and HDI + NE groups received HDI and the NE + Epi group received NE. Once a sustained MAP < 55 mmHg was reached (P₂), the HDI group received saline (NS), the HDI + NE group received NE and the NE + Epi group received Epi until death or censoring. P_tO₂ and hemodynamic parameters including MAP, cardiac output (CO) and central venous pressure (CVP) were measured every 10 minutes. Glucose and potassium were measured at predetermined intervals. Results: Animals treated with HDI + NE maintained P_tO₂ over time more than the HDI-alone group. Due to rapid hemodynamic collapse, we were unable to analyze P_tO₂ data in the vasopressor only animals. Mean survival time was 1.9, 2.9 and 0.1 hours for the HDI, HDI + NE and NE + Epi groups, respectively. Survival time from P₂ (sustained MAP <55 mmHg) to death or censoring was not different between HDI and HDI + NE groups. Conclusions: HDI + NE treatment was superior to HDI-alone at preserving P_tO₂ when MAP < 55 mmHg. We were unable to compare the P_tO₂ between the NE + Epi to the HDI or HDI + NE due to rapid decline in CO and death. If MAP is sustained at < 55 mmHg after maximizing HDI, adjunctive treatment with NE should be considered to preserve P_tO₂.

Are vasopressors useful in toxin-induced cardiogenic shock?

OBJECTIVE

Overdoses with cardio-depressive medications can result in toxin-induced cardiogenic shock (TICS), a life-threatening condition characterized by severe hypotension and ineffective tissue perfusion. Vasopressors are often employed in the treatment of shock to increase heart rate and blood pressure. We sought to conduct a systematic review of the literature to evaluate the effectiveness of vasopressors in improving hemodynamic function and survival in the treatment of TICS.

DATA SOURCES

We searched PubMed, EMBASE, TOXLINE, and International Pharmaceutical Abstracts.

STUDY SELECTION

We included studies evaluating the use of vasopressors in humans or animals with TICS. We limited human study types to randomized controlled trials, clinical trials, observational studies, and case reports.

DATA EXTRACTION

Our search yielded 913 citations and 144 of these met our inclusion criteria. 130 were human case reports and 14 were animal studies.

DATA SYNTHESIS

Human case report data showed vasopressors were ineffective more often than they were partially or fully effective. In the majority of animal studies, vasopressor treatment failed to improve hemodynamic parameters and resulted in decreased survival.

CONCLUSIONS

Human case reports and controlled animal experiments lead to different conclusions about vasopressors in TICS. Most animal studies indicate that vasopressors impair hemodynamic function and increase mortality. In contrast, human case reports suggest that vasopressors are often ineffective but not necessarily harmful.

Pilot Trial of Intravenous Lipid Emulsion Treatment for Severe Nifedipine-Induced Shock

Animal studies and human case reports show promise in using lipid rescue to treat refractory calcium channel antagonist toxicity. However, the majority of research and clinical experience has focused on non-dihydropyridine agents. Thus, we sought to investigate the value of lipid emulsion (ILE) therapy for dihydropyridine-induced shock. This IACUC-approved study utilized seven swine that were sedated with alpha-chloralose, mechanically ventilated, and instrumented for drug delivery and hemodynamic measures. After stabilization and basal measures, nifedipine (0.01875 mg/kg/min) was infused until imminent cardiac arrest (seizure, end tidal CO2 < 10 mmHg, bradydysrhythmia, or pulseless electrical activity). Animals then received a 7 mL/kg bolus of 20% lipid emulsion via central catheter. Lipid circulation was visually confirmed by the presence of fat in peripheral arterial blood. Hemodynamics were continuously monitored until 10 min after lipid bolus. Surviving animals were euthanized. Pre- and post-lipid treatment parameters were analyzed using the Wilxocon signed rank test (p <0.05 significant). Nifedipine toxicity was characterized by vasodilatory hypotension, impaired vascular contractility, and tachycardia with terminal bradycardia. The median time to imminent cardiac arrest from start of nifedipine infusion was 218 min. Lipid treatment did not improve hemodynamics or restore circulation in any animal. There was no benefit from lipid rescue in this model of nifedipine toxicity. Further study of ILE for dihydropyridine toxicity is warranted but initial animal model results are not promising.

Therapeutic role of hyperinsulinemia/euglycemia in aluminum phosphide poisoning

BACKGROUND

Different protocols have been suggested to treat aluminum phosphide (ALP) poisoning. We aimed to evaluate the possible therapeutic effect of hyperinsulinemia/euglycemia (HIE) in treatment of ALP poisoning.

METHODS

In a prospective interventional study, a total of 88 ALP-poisoned patients were included and assigned into HIE group undergoing glucose/insulin/potassium (GIK) protocol and a control group that was managed by routine conventional treatments. The 2 groups were then compared regarding the signs and symptoms of toxicity and their progression, development of complications, and final outcome to detect the possible effect of GIK protocol on the patients' course of toxicity and outcome.

RESULTS

The 2 groups were similar in terms of demographic characteristics and on-arrival vital signs and lab tests. Using GIK protocol resulted in significantly longer hospital stays (24 vs 60 hours; P < 0.001) and better outcomes (72.7% vs 50% mortality; P = 0.03). Regression analysis showed that GIK duration was an independent variable that could prognosticate mortality (odds ratio [95% confidence interval] = 1.045 [1.004,1.087]). The risk of mortality decreased by 4.5% each hour after initiation of GIK.

CONCLUSION

GIK protocol improves the outcome of ALP poisoning and increases the length of hospital stay.

Stability of high-dose insulin in normal saline bags for treatment of calcium channel blocker and beta blocker overdose

CONTEXT

High-dose insulin has become a first-line therapy for treating severe calcium channel blocker and beta blocker toxicity. Insulin infusions used to treat other conditions (e.g., diabetic ketoacidosis) may be used, but this may lead to pulmonary compromise due to fluid volume overload. An obvious solution would be to use a more concentrated insulin infusion; however, data describing the stability of insulin in polyvinyl chloride bags at concentrations >1 unit/mL are not readily available.

OBJECTIVE

To determine the stability of insulin at 16 units/mL in 0.9% saline solution.

MATERIALS AND METHODS

Eight-hundred units of regular insulin (8 mL from a stock vial containing 100 units/mL) were added to 42 mL of 0.9% saline solution in a polyvinyl chloride bag to make a final concentration of 16 units/mL. Two bags were stored at 4 °C (refrigerated) and two at 25 °C (room temperature). Samples were withdrawn and tested for insulin concentration periodically over 14 days.

RESULTS

Concentrated regular insulin in a polyvinyl chloride bag remained within 90% of equilibrium concentration at all time points, indicating the 16 units/mL concentration was sufficiently stable both refrigerated and at room temperature for 14 days.

DISCUSSION

Administration of high-dose insulin can cause fluid volume overload when using traditional insulin formulations. The 16 units/mL concentration allows for the treatment of a patient with severe calcium channel blocker or beta blocker toxicity for a reasonable period of time without administering excessive fluid.

CONCLUSION

Insulin at a concentration of 16 units/mL is stable for 14 days, the maximum timeframe currently allowed under US Pharmacopeia rules for compounding of sterile preparations. This stability data will allow institutions to issue beyond-use dating for intravenous fluids containing concentrated insulin and used for treating beta blocker and calcium channel blocker toxicity.

Calcium channel antagonist and beta-blocker overdose: antidotes and adjunct therapies

Management of cardiovascular instability resulting from calcium channel antagonist (CCB) or beta-adrenergic receptor antagonist (BB) poisoning follows similar principles. Significant myocardial depression, bradycardia and hypotension result in both cases. CCBs can also produce vasodilatory shock. Additionally, CCBs, such as verapamil and diltiazem, are commonly ingested in sustained-release formulations. This can also be the case for some BBs. Peak toxicity can be delayed by several hours. Provision of early gastrointestinal decontamination with activated charcoal and whole-bowel irrigation might mitigate this. Treatment of shock requires a multimodal approach to inotropic therapy that can be guided by echocardiographic or invasive haemodynamic assessment of myocardial function. High-dose insulin euglycaemia is commonly recommended as a first-line treatment in these poisonings, to improve myocardial contractility, and should be instituted early when myocardial dysfunction is suspected. Catecholamine infusions are complementary to this therapy for both inotropic and chronotropic support. Catecholamine vasopressors and vasopressin are used in the treatment of vasodilatory shock. Optimizing serum calcium concentration can confer some benefit to improving myocardial function and vascular tone after CCB poisoning. High-dose glucagon infusions have provided moderate chronotropic and inotropic benefits in BB poisoning. Phosphodiesterase inhibitors and levosimendan have positive inotropic effects but also produce peripheral vasodilation, which can limit blood pressure improvement. In cases of severe cardiogenic shock and/or cardiac arrest post-poisoning, extracorporeal cardiac assist devices have resulted in successful recovery. Other treatments used in refractory hypotension include intravenous lipid emulsion for lipophilic CCB and BB poisoning and methylene blue for refractory vasodilatory shock.

Management of a mixed overdose of calcium channel blockers, β-blockers and statins

We describe a case of extreme mixed overdose of calcium channel blockers, β-blockers and statins. The patient was successfully treated with aggressive resuscitation including cardiac pacing and multiorgan support, glucagon and high-dose insulin for toxicity related to calcium channel blockade and β-blockade, and ubiquinone for treating severe presumed statin-induced rhabdomyolysis and muscle weakness.

High dose insulin therapy, an evidence based approach to beta blocker/calcium channel blocker toxicity

Poison-induced cardiogenic shock (PICS) as a result of beta-blocker (β-blocker) or calcium channel blocker (CCB) overdose is a common and potentially life-threatening condition. Conventional therapies, including fluid resuscitation, atropine, cardiac pacing, calcium, glucagon, and vasopressors often fail to improve hemodynamic status. High-dose insulin (HDI) is an emerging therapeutic modality for PICS. In this article, we discuss the existing literature and highlight the therapeutic success and potential of HDI. Based on the current literature, which is limited primarily to case series and animal models, the authors conclude that HDI can be effective in restoring hemodynamic stability, and recommend considering its use in patients with PICS that is not responsive to traditional therapies. Future studies should be undertaken to determine the optimal dose and duration of therapy for HDI in PICS.

Cardioprotective effect of glucose-insulin on acute propafenone toxicity in rat

OBJECTIVE

We recently observed a case of propafenone self-poisoning in which the patient was initially unresponsive to conventional therapies such as sodium bicarbonate, dopamine, and norepinephrine but recovered with intravenous glucose-insulin infusion. We raised the hypothesis that insulin may have a cardioprotective effect in acute propafenone toxicity.

METHODS

We evaluated the effect of glucose-insulin infusion on mortality and electrocardiographic abnormalities during acute propafenone toxicity in rats. After measurements of basal mean arterial pressure, heart rate, PR interval, and QRS duration, rats received intravenous propafenone (36 mg/kg per hour) for 12 minutes. Two minutes after the induction of toxicity, the rats (n=10 per group) received either normal saline solution (NSS) or insulin with glucose. Rats in the insulin-treated (Insulin group) and the NSS-treated (NSS group) groups received an intravenous infusion of 36 mg/kg per hour of propafenone until death occurred. Rats receiving only NSS intravenously without propafenone toxicity served as control (Control group, n=10).

RESULTS

Insulin treatment improved survival and delayed the hemodynamic and electrocardiographic consequences of propafenone toxicity. Survival was significantly greater in the insulin group than that in the NSS group (P<.001). Insulin prevented the decline in mean arterial pressure and heart rate (P<.05). Insulin also prevented the increase of the PR interval and the QRS duration (P<.05).

CONCLUSION

Glucose-insulin infusion delayed the abnormalities in cardiac conduction and improved rat survival after acute propafenone toxicity. These results suggest a cardioprotective effect of glucose-insulin in acute propafenone toxicity.

Toxic bradycardias in the critically ill poisoned patient

Cardiovascular drugs are a common cause of poisoning, and toxic bradycardias can be refractory to standard ACLS protocols. It is important to consider appropriate antidotes and adjunctive therapies in the care of the poisoned patient in order to maximize outcomes. While rigorous studies are lacking in regards to treatment of toxic bradycardias, there are small studies and case reports to help guide clinicians' choices in caring for the poisoned patient. Antidotes, pressor support, and extracorporeal therapy are some of the treatment options for the care of these patients. It is important to make informed therapeutic decisions with an understanding of the available evidence, and consultation with a toxicologist and/or regional Poison Control Center should be considered early in the course of treatment.

Levosimendan Does Not Improve Cardiac Output or Blood Pressure in a Rodent Model of Propranolol Toxicity When Administered Using Various Dosing Regimens

Background: Levosimendan (CAS: 141505-33-1) is a myocardial calcium sensitizer that improves myocardial contractility in various forms of heart failure. It produces a moderate improvement in cardiac output (CO) without an improvement in blood pressure (BP) in verapamil and metoprolol poisoned rodents. Aim: To assess the effect of various levosimendan dosing regimens on hemodynamics in a rodent model of propranolol poisoning. Method: Male Wistar rats (350-450 g) were anesthetized, ventilated, and instrumented to record BP, heart rate (HR), and CO. Propranolol was infused continually. When BP dropped to 50% of baseline rats received 1 of 7 treatments: (1) 0.9% saline (control), (2) levosimendan 36 μg/kg loading dose then 0.6 μg/kg per min, (3) levosimendan 0.6 μg/kg per min, (4) epinephrine 0.5 μg/kg per min, (5) levosimendan 70 μg/kg loading dose then 1.2 μg/kg per min, (6) levosimendan 1.2 μg/kg per min, and (7) levosimendan 70 μg/kg loading dose alone. Hemodynamics were recorded every 10 minutes for 70 minutes. Cardiac output, mean arterial pressure, and HR for each group were compared with control. Results: All groups had comparable baseline and maximal toxicity hemodynamics prior to initiation of treatment. Levosimendan did not improve CO or BP with any dosing regimen. Blood pressure tended to be lower than control for all doses of levosimendan. Epinephrine significantly improved BP but not CO compared to all other treatment groups. Survival did not differ between groups. Conclusions: Unlike in verapamil and metoprolol poisoning models, levosimendan did not improve CO or survival in propranolol poisoning. Epinephrine improved BP, but not CO, suggesting that its actions were due to peripheral vasoconstriction.

Levosimendan infusion improves cardiac output but not blood pressure in a rodent model of severe metoprolol toxicity

Levosimendan (Levo) is an inodilator improving cardiac output (CO) and reducing afterload in heart failure. Previously, we reported that Levo improved CO but not blood pressure (BP) in a rodent model of verapamil poisoning. We theorised that Levo-induced vasodilation should not influence BP to a similar degree in metoprolol poisoning. Aim: To assess the effect of Levo on haemodynamics in a rodent model of metoprolol poisoning. Method: Anaesthetized male Wistar rats were infused metoprolol continuously. When the BP dropped to 50% of baseline (time 0) rats received 1 of the 4 treatments: (a) control (0.9% saline bolus + infusion); (b) Levo-l (Levo 36 μm/kg loading dose followed by 0.6 μm/kg/min); (c) Levo-I (Levo infusion only at 0.6 μm/kg/min); and (d) Epi (epinephrine 0.5 μm/kg/min). All groups received comparable fluid volumes. Haemodynamics were recorded every 10 min for 70 min. CO, mean arterial pressure (MAP) and heart rate (HR) of each group were compared to the control. Results: All groups had comparable baseline and time 0 HR, MAP and CO. Levo-L and Levo-I rats showed significantly greater CO at t = 10 min ( p > 0.02 and p > 0.04, respectively). CO was higher at all other time points for both Levo groups. This was not statistically significant. Levo did not improve MAP compared to control. Adrenaline increased MAP but not CO compared to control and Levo groups. Conclusion: Levo did not improve MAP but moderately improved CO compared to control in this model of metoprolol poisoning. The response was similar to that reported previously in verapamil-poisoned rats. The improvement in MAP seen with epinephrine was most likely vasoconstriction mediated.

Insulin versus Lipid Emulsion in a Rabbit Model of Severe Propranolol Toxicity: A Pilot Study

Background and objective. Beta-blocker overdose may result in intractable cardiovascular collapse despite conventional antidotal treatments. High dose insulin/glucose (ING), and more recently intravenous lipid emulsion (ILE), have been proposed as potentially beneficial therapies in beta blocker intoxication. We compare efficacy of the novel antidotes ING, with ILE, in a rabbit model of combined enteric/intravenous propranolol toxicity. Methods. Sedated, mechanically ventilated and invasively monitored New Zealand White rabbits underwent mini-laparotomy and enterostomy formation with 40 mg/kg propranolol instilled into the proximal small bowel. At 30 minutes propranolol infusion was commenced at 4 mg/kg/hr and continued to a target mean arterial pressure (MAP) of 50% baseline MAP. Animals were resuscitated with insulin at 3 U/kg plus 0.5 g/kg glucose (ING group), or 10 mL/kg 20% Intralipid (ILE group). Results. Rate pressure product (RPP; RPP = heart rate × mean arterial pressure) was greatest in the ING group at 60 minutes (P < .05). A trend toward greater heart rate was observed in the ING group (P = .06). No difference was observed in survival between groups (4/5 ING versus 2/5 ILE; P = .524). Conclusions. High dose insulin resulted in greater rate pressure product compared with lipid emulsion in this rabbit model of severe enteric/intravenous propranolol toxicity.

Addition of phenylephrine to high-dose insulin in dihydropyridine overdose does not improve outcome

INTRODUCTION

Vasopressors are commonly used for calcium channel blocker (CCB)-induced cardiogenic shock after calcium and high-dose insulin (HDI). Vasopressor therapy is frequently used in combination with HDI to increase blood pressure and improve outcome. However, no studies have compared the efficacy of HDI to the combination of a vasopressor and HDI in dihydropyridine overdose. We conducted a study to compare the efficacy of HDI to phenylephrine (PE) plus HDI in a porcine model of dihydropyridine toxicity.

METHODS

Cardiogenic shock was induced by administering a nifedipine (NP) infusion of 0.0125 mcg/kg/min until a point of toxicity, defined as a 25% decrease in the baseline product of mean arterial pressure (MAP) × cardiac output (CO). Each arm was resuscitated with 20 mL/kg of saline (NS). The nifedipine infusion continued throughout a 4-h resuscitation protocol. The HDI group was titrated up to 10 units/kg/h of insulin and the HDI/PE group was titrated up to a dose of HDI 10 units/kg/h plus PE 3.6 mcg/kg/min.

RESULTS

No baseline differences were found among groups including time to toxicity. Survival was not different between the HDI and HDI/PE arms. When comparing the HDI to the HDI/PE arm no differences were found for cardiac index (CI) (p = 0.06), systemic vascular resistance (p = 0.34), heart rate (HR) (p = 0.95), mean arterial pressure (p = 0.99), pulmonary vascular resistance (PVR) (p = 0.07), or base excess (p = 0.36).

CONCLUSION

In this model of nifedipine-induced cardiogenic shock, the addition of PE to HDI therapy did not improve mortality, cardiac output, blood pressure, systemic vascular resistance (SVR), or base excess.

Drugs and pharmaceuticals: management of intoxication and antidotes

The treatment of patients poisoned with drugs and pharmaceuticals can be quite challenging. Diverse exposure circumstances, varied clinical presentations, unique patient-specific factors, and inconsistent diagnostic and therapeutic infrastructure support, coupled with relatively few definitive antidotes, may complicate evaluation and management. The historical approach to poisoned patients (patient arousal, toxin elimination, and toxin identification) has given way to rigorous attention to the fundamental aspects of basic life support--airway management, oxygenation and ventilation, circulatory competence, thermoregulation, and substrate availability. Selected patients may benefit from methods to alter toxin pharmacokinetics to minimize systemic, target organ, or tissue compartment exposure (either by decreasing absorption or increasing elimination). These may include syrup of ipecac, orogastric lavage, activated single- or multi-dose charcoal, whole bowel irrigation, endoscopy and surgery, urinary alkalinization, saline diuresis, or extracorporeal methods (hemodialysis, charcoal hemoperfusion, continuous venovenous hemofiltration, and exchange transfusion). Pharmaceutical adjuncts and antidotes may be useful in toxicant-induced hyperthermias. In the context of analgesic, anti-inflammatory, anticholinergic, anticonvulsant, antihyperglycemic, antimicrobial, antineoplastic, cardiovascular, opioid, or sedative-hypnotic agents overdose, N-acetylcysteine, physostigmine, L-carnitine, dextrose, octreotide, pyridoxine, dexrazoxane, leucovorin, glucarpidase, atropine, calcium, digoxin-specific antibody fragments, glucagon, high-dose insulin euglycemia therapy, lipid emulsion, magnesium, sodium bicarbonate, naloxone, and flumazenil are specifically reviewed. In summary, patients generally benefit from aggressive support of vital functions, careful history and physical examination, specific laboratory analyses, a thoughtful consideration of the risks and benefits of decontamination and enhanced elimination, and the use of specific antidotes where warranted. Data supporting antidotes effectiveness vary considerably. Clinicians are encouraged to utilize consultation with regional poison centers or those with toxicology training to assist with diagnosis, management, and administration of antidotes, particularly in unfamiliar cases.

The use of high-dose insulin-glucose euglycemia in beta-blocker overdose: a case report

The management of life-threatening beta-blocker toxicity and its associated low cardiac output state is clinically challenging. Previous case reports and case series describe the use of hyperinsulinemia/euglycemia therapy in mono-ingestions of calcium channel blockers and mixed ingestions, including calcium channel and beta-blockers. In this case report we describe the use of high-dose insulin (10 IU/kg per hour) in a case of massive metoprolol ingestion (5g) in which hypotension was unresponsive to conventional therapies. Although the metoprolol concentrations measured in plasma were approximately 100-200 times therapeutic concentrations, the pharmacokinetics appeared to be similar to therapeutic metoprolol dosing.

Insulin versus vasopressin and epinephrine to treat β-blocker toxicity

OBJECTIVE

We compared insulin and glucose (IN/G) to vasopressin plus epinephrine (V/E) in a pig model of beta-blocker toxicity. Primary outcome was survival over four hours.

METHODS

Ten pigs received a 0.5 mg/kg bolus of propranolol IV followed by a continuous infusion. At the point of toxicity 20 ml/kg normal saline was rapidly infused and the propranolol drip continued at 0.125 mg/kg/min over four hours of resuscitation. Each pig was randomized to either IN/G or V/E. The V/E group began with epinephrine at 10 mcg/kg/min titrated up by 10 mcg/kg/min every 10 min to 50 mcg/kg/min or until baseline was obtained. Simultaneously, these pigs received vasopressin at 0.0028 units/kg/min, titrated upwards every 10 min to 0.014 units/kg/min or until baseline was obtained. The IN/G group began with a 2 units/kg/hr drip and increased by 2 units every 10 minutes to 10 units/kg/hr, or until baseline hemodynamics were obtained. CO, SVR, systolic blood pressure, HR, MAP, glucose, and potassium were monitored. Glucose was given for values <60 mg/dl.

RESULTS

The study was terminated early due to marked survival differences after five pigs were entered in each group. All IN/G group pigs survived four hours. All V/E group pigs died within 90 min. CO in the IN/G group increased throughout the four hours, rising above pre-propranolol levels, while MAP, SBP, and SVR all trended slightly downward. CO in the V/E group dropped until death, while MAP, SBP, and SVR rose precipitously until 30-60 minutes when these dropped abruptly until death. Glucose was required in the IN/G group.

CONCLUSION

In this swine model, IN/G is superior to V/E to treat beta-blocker toxicity. IN/G has marked inotropic properties while the vasopressor effects of V/E depress CO and contribute to death. Increasing SVR in this condition is detrimental to survival.