Prehospital administration of hydroxocobalamin for smoke inhalation-associated cyanide poisoning: 8 years of experience in the Paris Fire Brigade

Poisoning-Induced Acute Kidney Injury: A Review

Acute kidney injury (AKI) is a debilitating, multi-etiological disease that is commonly seen in clinical practice and in the emergency department. In this review, we introduce the definition, symptoms, and causes of poisoning-related AKI; we also discuss its mechanisms, risk factors, and epidemiology, as well as elaborate on the relevant laboratory tests. Subsequently, we discuss the treatment strategies for toxin- and substance-related AKI caused by Glafenin, antimicrobial agents, lithium, contrast media, snake venom, herbicides, ethylene glycol, synthetic cannabinoids, cocaine, heroin, and amphetamines. Finally, for a comprehensive overview of poisoning-related AKI, we review the management, prevention, and outcomes of this condition.

Time to Burn? Characteristics of Hydroxocobalamin Administration in an Academic Medical Center

Background/Objective: Hydroxocobalamin is indicated for cyanide poisoning and its package insert states it should be given "without delay". We sought to evaluate time to administration and clinical characteristics when hydroxocobalamin was administered in a quaternary care academic medical center. Methods: All hydroxocobalamin administrations from January 1, 2007 to December 31, 2018 were analyzed. Data points recorded were: carboxyhemoglobin, cyanide and methemoglobin levels, hospital time and course, time and dose of hydroxocobalamin administration, lactate and bicarbonate levels, initial and nadir pH, initial heart rate, and initial and lowest systolic blood pressure. Results: Fifty-six cases were identified. One case was excluded as hydroxocobalamin was administered for nitroprusside toxicity. Among 55 cases analyzed, 93% (n = 51) were adults. Median hospital length of stay was 4.3 days (IQR 2.5 to 12). Burn, inhalation injury, and smoke inhalation were 80% of admitting diagnoses. Median time to hydroxocobalamin administration was 208 minutes (IQR 62.5 to 330). Eleven of 55 cases died. Hydroxocobalamin was given within 60 minutes of arrival in 12 cases, of which 3 died. All adults received 5 g of hydroxocobalamin. Time to hydroxocobalamin administration was longer in death cases [median: 221 minutes (IQR 119 to 594)] vs survivors [median: 184.5 minutes (IQR 62.8 to 315)]. Seventeen cases had cyanide levels drawn, with 9 being measurable, but none were toxic. Conclusions: Significant delay in hydroxocobalamin administration was seen in this study. Cases that resulted in death had significantly longer times to hydroxocobalamin administration. Further studies are warranted to identify reasons for delays in hydroxocobalamin administration.

Acute care for burn patients: fluids, surgery, and what else?

PURPOSE OF REVIEW

Recently published initiatives spanning the burn care spectrum have substantially changed the standard of care in burn care. The purpose of this article is to describe new impactful concepts in burn first aid, triage, resuscitation, and treatment as well as their impact on future research.

RECENT FINDINGS

First aid after burn injury traditionally consists of extinguishing the burn and applying dressings. Recent evidence suggests that applying 20 min of cool tap water to the burn wound in the first 3 h postburn mitigates burn injury extent. National burn center transfer criteria have been updated, impacting patient initial transfer and management. The adverse effects of hydroxocobalamin, a commonly used antidote for cyanide toxicity, have been delineated. Initial burn resuscitation recommendations for both volume and potentially fluid type are being reexamined. The emergence of innovative skin substitutes may improve burn survival by providing a physiologically stabilizing intermediate dressing. Finally, formal clinical practice guidelines for early mobility in the ICU after burn injury have been defined.

SUMMARY

These changes in burn care, triage, resuscitation, and treatment have challenged traditional burn care standards, created new standards, and are the basis for future prospective randomized trials.

Various injury patterns due to combustion (typical but unfamiliar to physicians and easy to miss) in Korea: a case report

Patients transported from fire sites may exhibit various injury patterns. Major trauma, skin burn, inhalation burn, and carbon monoxide poisoning are typical injuries. However, most physicians may be unfamiliar that cyanide poisoning can frequently occur due to combustion. Cyanide poisoning is highly significant owing to high mortality and the existence of antidotes. I present a 35-year-old man who was transported from a burning building and suffered severe metabolic acidosis despite no major bleeding as well as mild carbon monoxide poisoning. I suspected cyanide poisoning and administered the antidote; subsequently, the patient showed improvement. The next day, sudden airway obstruction developed, and emergency endotracheal intubation was performed. The inhalation damage was detected only in the lower airway tract and not in the upper airway. Physicians should be aware of cyanide poisoning and inhalation burn to avoid missing treatment opportunities.

2023 American Heart Association Focused Update on the Management of Patients With Cardiac Arrest or Life-Threatening Toxicity Due to Poisoning: An Update to the American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care

In this focused update, the American Heart Association provides updated guidance for resuscitation of patients with cardiac arrest, respiratory arrest, and refractory shock due to poisoning. Based on structured evidence reviews, guidelines are provided for the treatment of critical poisoning from benzodiazepines, β-adrenergic receptor antagonists (also known as β-blockers), L-type calcium channel antagonists (commonly called calcium channel blockers), cocaine, cyanide, digoxin and related cardiac glycosides, local anesthetics, methemoglobinemia, opioids, organophosphates and carbamates, sodium channel antagonists (also called sodium channel blockers), and sympathomimetics. Recommendations are also provided for the use of venoarterial extracorporeal membrane oxygenation. These guidelines discuss the role of atropine, benzodiazepines, calcium, digoxin-specific immune antibody fragments, electrical pacing, flumazenil, glucagon, hemodialysis, hydroxocobalamin, hyperbaric oxygen, insulin, intravenous lipid emulsion, lidocaine, methylene blue, naloxone, pralidoxime, sodium bicarbonate, sodium nitrite, sodium thiosulfate, vasodilators, and vasopressors for the management of specific critical poisonings.

Cost impact of hydroxocobalamin in the treatment of patients with known or suspected cyanide poisoning due to smoke inhalation from closed-space fires

BACKGROUND & OBJECTIVES

Cyanide poisoning can occur due to exposure to smoke in closed-space fires. With no point of care cyanide test at the scene of a fire, first responders and clinicians base decisions to treat with cyanide antidote on patient history, clinical signs, and other indirect data points that have not been proven to correspond with actual systemic levels of cyanide. The aim of this exploratory study was to determine the economic implications of treating patients with known or suspected cyanide poisoning due to smoke inhalation with hydroxocobalamin.

METHODS

A decision analysis model was developed from the US hospital perspective. Healthcare resource utilization was estimated from a retrospective evaluation of clinical outcomes in hydroxocobalamin-treated patients and in historical controls without hydroxocobalamin use (Nguyen, et al. 2017). Epidemiologic parameters and costs were estimated from the published literature, and publicly-available hospital charges were identified. Outcomes reported in the analysis included expected healthcare resource utilization in the US population and per-patient costs with and without the use of hydroxocobalamin. A cost-to-charge ratio was applied so that all costs would reflect hospital costs rather than hospital charges. Deterministic sensitivity analysis was performed to identify the most influential model parameters. All costs were reported in 2017 US dollars.

RESULTS

Use of hydroxocobalamin reduces healthcare resource utilization and contributes to decreased per-patient hospital costs ($15,381 with hydroxocobalamin treatment versus $22,607 with no cyanide antidote). The most substantive cost-savings resulted from decreased hospital length of stay (i.e., intensive care unit [ICU] and non-ICU). Costs attributed to mechanical ventilation also decreased with use of hydroxocobalamin. A univariate sensitivity analysis demonstrated that the most impactful variables in the cost analysis were related to hospital length of stay (ICU followed by non-ICU stay), followed by the daily cost of ICU stay.

CONCLUSIONS

Use of hydroxocobalamin in patients with known or suspected cyanide poisoning from closed-space fire smoke inhalation may decrease hospital costs and contribute to more efficient healthcare resource utilization.

Evaluation of prehospital hydroxocobalamin use in the setting of smoke inhalation

BACKGROUND

The indications for prehospital hydroxocobalamin are not well defined. The aim of this study was to evaluate prehospital signs and symptoms in patients who received hydroxocobalamin to improve future use.

METHODS

In this retrospective study, all patients who received prehospital Hydroxocobalamin at a tertiary care burn center from December 2012 to March 2018 were reviewed. Each case was evaluated for evidence of suspected cyanide toxicity: hypotension, syncope, CNS depression/altered mentation, seizures, respiratory or cardiac arrest. A determination was made whether or not hydroxocobalamin was indicated.

RESULTS

In this study, EMS providers administered hydroxocobalamin to 42 patients between December 2012 and March 2018. The majority (71%) of suspected cyanide exposures were from house fires. The most common prehospital findings were coma or depressed CNS (36%), followed by hypotension (16%) and cardiac arrest (12%). Sixty percent of patients treated with hydroxocobalamin had none of the six clinical indicators for potential cyanide toxicity. Carboxyhemoglobin and serum lactate were significantly different in patients that had a clinical indication for hydroxocobalamin compared to those who did not.

CONCLUSIONS

Prehospital hydroxocobalamin was used empirically however, indications are unclear. Using defined clinical indications may provide greater clarity for providers and reduce unnecessary use of hydroxocobalamin.

Life-Threatening Cyanide Intoxication after Ingestion of Amygdalin in Prehospital Care

Amygdalin is originally a natural cyanogenic glycoside available as a dietary supplement used in the alternative treatment of cancer patients. Amygdalin hydroxylates to toxic cyanide in the body, which can cause life-threatening intoxication. The case report presents a 72-year-old patient with life-threatening cyanide poisoning after ingesting a dietary supplement containing amygdalin identified in prehospital care, which was successfully treated with hydroxocobalamin.

Hydroxocobalamin interference in routine laboratory tests: Development of a protocol for identifying samples and reporting results from patients treated with CyanokitTM

OBJECTIVES

Hydroxocobalamin (OHCob) is an antidote for cyanide poisoning in patients rescued from house fires and is known to cause interference with certain laboratory tests. Consensus is lacking on the extent of this interference and on how to handle these samples. The objectives of this study were to characterize OHCob interference across a wide range of laboratory tests and to develop protocols for identifying and reporting these samples.

DESIGNS & METHODS

Patient plasma samples (n = 5) were spiked with OHCob (1.5 mg/mL) and compared to controls without this drug. A series of analytes were measured using chemistry, urinalysis, coagulation, hematology, and blood gas instruments. Dose-response testing was performed on a subset of assays that showed interferences ≥10%.

RESULTS

Of the 77 analytes evaluated, 27 (35%) showed interference from OHCob, with chemistry and coagulation analytes showing the greatest effects. Of those affected, 22 analytes had a positive interference, whereas 5 analytes had negative interference. Dose-response studies showed dose-dependent increases and/or decreases consistent with initial spiking studies. Although red in colour, plasma samples with OHCob did not trigger hemolysis index flags, necessitating a special sample identification and reporting protocol.

CONCLUSION

OHCob had significant effects on several analytes across different instruments. These findings led to the development of special sample handling and reporting protocols to identify OHCob samples and ensure only accurate results are released. It is vital for emergency departments to document and notify their laboratories whenever blood samples from these patients are drawn.

Advances in airway management and mechanical ventilation in inhalation injury

PURPOSE OF REVIEW

Airway management, mechanical ventilation, and treatment of systemic poisoning in burn patients with inhalation injury remains challenging. This review summarizes new concepts as well as open questions.

RECENT FINDINGS

Several life-threatening complications, such as airway patency impairment and respiratory insufficiency, can arise in burn patients and require adequate and timely airway management. However, unnecessary endotracheal intubation should be avoided. Direct visual inspection via nasolaryngoscopy can guide appropriate airway management decisions. In cases of lower airway injury, bronchoscopy is recommended to remove casts and estimate the extent of the injury in intubated patients. Several mechanical ventilation strategies have been studied. An interesting modality might be high-frequency percussive ventilation. However, to date, there is no sound evidence that patients with inhalation injury should be ventilated with modes other than those applied to non-burn patients. In all burn patients exposed to enclosed fire, carbon monoxide as well as cyanide poisoning should be suspected. Carbon monoxide poisoning should be treated with an inspiratory oxygen fraction of 100%, whereas cyanide poisoning should be treated with hydroxocobalamin.

SUMMARY

Burn patients need specialized care that requires specific knowledge about airway management, mechanical ventilation, and carbon monoxide and cyanide poisoning.

Data quality of Glasgow Coma Scale and Systolic Blood Pressure in scientific studies involving physician-staffed emergency medical services: Systematic review

BACKGROUND

Emergency physicians on-scene provide highly specialized care to severely sick or injured patients. High-quality research relies on the quality of data, but no commonly accepted definition of EMS data quality exits. Glasgow Coma Score (GCS) and Systolic Blood Pressure (SBP) are core physiological variables, but little is known about the quality of these data when reported in p-EMS research. This systematic review aims to describe the quality of pre-hospital reporting of GCS and SBP data in studies where emergency physicians are present on-scene.

METHODS

A systematic literature search was performed using CINAHL, Cochrane, Embase, Medline, Norart, Scopus, SweMed + and Web of Science, in accordance with the PRISMA guidelines. Reported data on accuracy of reporting, completeness and capture were extracted to describe the quality of documentation of GCS and SBP. External and internal validity assessment was performed by extracting a set of predefined variables.

RESULTS

We included 137 articles describing data collection for GCS, SBP or both. Most studies (81%) were conducted in Europe and 59% of studies reported trauma cases. Reporting of GCS and SBP data were not uniform and may be improved to enable comparisons. Of the predefined external and internal validity data items, 26%-45% of data were possible to extract from the included papers.

CONCLUSIONS

Reporting of GCS and SBP is variable in scientific papers. We recommend standardized reporting to enable comparisons of p-EMS.

Association between hydroxocobalamin administration and acute kidney injury after smoke inhalation: a multicenter retrospective study

Background

The use of hydroxocobalamin has long been advocated for treating suspected cyanide poisoning after smoke inhalation. Intravenous hydroxocobalamin has however been shown to cause oxalate nephropathy in a single-center study. The impact of hydroxocobalamin on the risk of acute kidney injury (AKI) and survival after smoke inhalation in a multicenter setting remains unexplored.

Methods

We conducted a multicenter retrospective study in 21 intensive care units (ICUs) in France. We included patients admitted to an ICU for smoke inhalation between January 2011 and December 2017. We excluded patients discharged at home alive within 24 h of admission. We assessed the risk of AKI (primary endpoint), severe AKI, major adverse kidney (MAKE) events, and survival (secondary endpoints) after administration of hydroxocobalamin using logistic regression models.

Results

Among 854 patients screened, 739 patients were included. Three hundred six and 386 (55.2%) patients received hydroxocobalamin. Mortality in ICU was 32.9% (n = 243). Two hundred eighty-eight (39%) patients developed AKI, including 186 (25.2%) who developed severe AKI during the first week. Patients who received hydroxocobalamin were more severe and had higher mortality (38.1% vs 27.2%, p = 0.0022). The adjusted odds ratio (95% confidence interval) of AKI after intravenous hydroxocobalamin was 1.597 (1.055, 2.419) and 1.772 (1.137, 2.762) for severe AKI; intravenous hydroxocobalamin was not associated with survival or MAKE with an adjusted odds ratio (95% confidence interval) of 1.114 (0.691, 1.797) and 0.784 (0.456, 1.349) respectively.

Conclusion

Hydroxocobalamin was associated with an increased risk of AKI and severe AKI but was not associated with survival after smoke inhalation.

Trial registration

ClinicalTrials.gov, NCT03558646

The central role of protein kinase C epsilon in cyanide cardiotoxicity and its treatment

In adult mouse myocytes, brief exposure to sodium cyanide (CN) in the presence of glucose does not decrease ATP levels, yet produces profound reduction in contractility, intracellular Ca2+ concentration ([Ca2+]i) transient and L-type Ca2+ current (ICa) amplitudes. We analyzed proteomes from myocytes exposed to CN, focusing on ionic currents associated with excitation-contraction coupling. CN induced phosphorylation of α1c subunit of L-type Ca2+ channel and α2 subunit of Na+-K+-ATPase. Methylene blue (MB), a CN antidote that we previously reported to ameliorate CN-induced reduction in contraction, [Ca2+]i transient and ICa amplitudes, was able to reverse this phosphorylation. CN decreased Na+-K+-ATPase current contributed by α2 but not α1 subunit, an effect that was also counteracted by MB. Peptide consensus sequences suggested CN-induced phosphorylation was mediated by protein kinase C epsilon (PKCε). Indeed, CN stimulated PKC kinase activity and induced PKCε membrane translocation, effects that were prevented by MB. Pre-treatment with myristoylated PKCε translocation activator or inhibitor peptides mimicked and inhibited the effects of CN on ICa and myocyte contraction, respectively. We conclude that CN activates PKCε, which phosphorylates L-type Ca2+ channel and Na+-K+-ATPase, resulting in depressed cardiac contractility. We hypothesize that this inhibition of ion fluxes represents a novel mechanism by which the cardiomyocyte reduces its ATP demand (decreased ion fluxes and contractility), diminishes ATP turnover and preserves cell viability. However, this cellular protective effect translates into life-threatening cardiogenic shock in vivo, thereby creating a profound disconnect between survival mechanisms at the cardiomyocyte level from those at the level of the whole organism.

Methylene blue counteracts cyanide cardiotoxicity: cellular mechanisms

In adult left ventricular mouse myocytes, exposure to sodium cyanide (NaCN) in the presence of glucose dose-dependently reduced contraction amplitude, with ~80% of maximal inhibitory effect attained at 100 µM. NaCN (100 µM) exposure for 10 min significantly decreased contraction and intracellular Ca2+ concentration ([Ca2+]i) transient amplitudes, systolic but not diastolic [Ca2+]i, and maximal L-type Ca2+ current ( ICa) amplitude, indicating acute alteration of [Ca2+]i homeostasis largely accounted for the observed excitation-contraction abnormalities. In addition, NaCN depolarized resting membrane potential ( Em), reduced action potential (AP) amplitude, prolonged AP duration at 50% (APD50) and 90% repolarization (APD90), and suppressed depolarization-activated K+ currents but had no effect on Na+-Ca2+ exchange current ( INaCa). NaCN did not affect cellular adenosine triphosphate levels but depolarized mitochondrial membrane potential (ΔΨm) and increased superoxide (O2·-) levels. Methylene blue (MB; 20 µg/ml) added 3 min after NaCN restored contraction and [Ca2+]i transient amplitudes, systolic [Ca2+]i, Em, AP amplitude, APD50, APD90, ICa, depolarization-activated K+ currents, ΔΨm, and O2·- levels toward normal. We conclude that MB reversed NaCN-induced cardiotoxicity by preserving intracellular Ca2+ homeostasis and excitation-contraction coupling ( ICa), minimizing risks of arrhythmias ( Em, AP configuration, and depolarization-activated K+ currents), and reducing O2·- levels. NEW & NOTEWORTHY Cyanide poisoning due to industrial exposure, smoke inhalation, and bioterrorism manifests as cardiogenic shock and requires rapidly effective antidote. In the early stage of cyanide exposure, adenosine triphosphate levels are normal but myocyte contractility is reduced, largely due to alterations in Ca2+ homeostasis because of changes in oxidation-reduction environment of ion channels. Methylene blue, a drug approved by the U.S. Food and Drug Administration, ameliorates cyanide toxicity by normalizing oxidation-reduction state and Ca2+ channel function.

Case Files of the University of Massachusetts Toxicology Fellowship: Does This Smoke Inhalation Victim Require Treatment with Cyanide Antidote?

Cyanide toxicity is common after significant smoke inhalation. Two cases are presented that provide framework for the discussion of epidemiology, pathogenesis, presenting signs and symptoms, and treatment options of inhalational cyanide poisoning. An evidence-based algorithm is proposed that utilizes point-of-care testing to help physicians identify patients who benefit most from antidotal therapy.

Utility and outcomes of hydroxocobalamin use in smoke inhalation patients

INTRODUCTION

Hydroxocobalamin has been available for use for suspected cyanide toxicity in smoke inhalation patients in the United States since 2006. Our study compares outcomes of patients who received hydroxocobalamin to historical controls who did not.

METHODS

In this retrospective review, patients administered hydroxocobalamin (2008-2014) were compared to historical controls (2002-2008). Patients <18 years, patients who received an alternate antidote, and patients without suspicion of smoke inhalation injury were excluded. Mortality was the primary outcome. Secondary outcomes evaluated were 7-day change in creatinine, culture-proven pneumonia, days on mechanical ventilation, ventilator- free days (VFD), ICU length of stay (ICU LOS), and hospital length of stay (HLOS).

RESULTS

A total of 138 patients in the hydroxocobalamin group and 135 in the control group were identified. Mortality rate was similar between both groups (29% vs. 28%, p=0.90). Hydroxocobalamin was associated with lower pneumonia rate (23% vs. 49%, p<0.01), less ventilator days (4 days vs. 7 days, p<0.01), and increased VFD (20 days vs. 11 days, p=0.01) compared to controls. Shorter ICU LOS (6 days vs. 10 days, p=0.03) and a trend toward lower HLOS (7 day vs. 11 days, p=0.06) were also found in patients who received hydroxocobalamin.

CONCLUSIONS

Routine administration was associated with lower rate of pneumonia, faster liberation from the ventilator, and reductions in intensive care unit stay. Burn centers should consider its empiric use in suspected smoke inhalation patients.

Initial evaluation and management of the critical burn patient

The major improvement in burn therapy is likely to focus on the early management of hemodynamic and respiratory failures in combination with an aggressive and early surgical excision and skin grafting for full-thickness burns. Immediate burn care by first care providers is important and can vastly alter outcomes, and it can significantly limit burn progression and depth. The goal of prehospital care should be to cease the burning process as well as prevent future complications and secondary injuries for burn shock. Identifying burn patients appropriate for immediate or subacute transfer is an important step in reducing morbidity and mortality. Delays in transport to Burn Unit should be minimized. The emergency management follows the principles of the Advanced Trauma Life Support Guidelines for assessment and stabilization of airway, breathing, circulation, disability, exposure and environment control. All patients with suspected inhalation injury must be removed from the enclosure as soon as possible, and immediately administer high-flow oxygen. Any patient with stridor, shortness of breath, facial burns, singed nasal hairs, cough, soot in the oral cavity, and history of being in a fire in an enclosed space should be strongly considered for early intubation. Fibroscopy may also be useful if airway damage is suspected and to assess known lung damage. Secondary evaluation following admission to the Burn Unit of a burned patient suffering a severe thermal injury includes continuation of respiratory support and management and treatment of inhalation injury, fluid resuscitation and cardiovascular stabilization, pain control and management of burn wound.

Pre-hospital emergency medicine

Pre-hospital care is emergency medical care given to patients before arrival in hospital after activation of emergency medical services. It traditionally incorporated a breadth of care from bystander resuscitation to statutory emergency medical services treatment and transfer. New concepts of care including community paramedicine, novel roles such as emergency care practitioners, and physician delivered pre-hospital emergency medicine are re-defining the scope of pre-hospital care. For severely ill or injured patients, acting quickly in the pre-hospital period is crucial with decisions and interventions greatly affecting outcomes. The transfer of skills and procedures from hospital care to pre-hospital medicine enables early advanced care across a range of disciplines. The variety of possible pathologies, challenges of environmental factors, and hazardous situations requires management that is tailored to the patient's clinical need and setting. Pre-hospital clinicians should be generalists with a broad understanding of medical, surgical, and trauma pathologies, who will often work from locally developed standard operating procedures, but who are able to revert to core principles. Pre-hospital emergency medicine consists of not only clinical care, but also logistics, rescue competencies, and scene management skills (especially in major incidents, which have their own set of management principles). Traditionally, research into the hyper-acute phase (the first hour) of disease has been difficult, largely because physicians are rarely present and issues of consent, transport expediency, and resourcing of research. However, the pre-hospital phase is acknowledged as a crucial period, when irreversible pathology and secondary injury to neuronal and cardiac tissue can be prevented. The development of pre-hospital emergency medicine into a sub-specialty in its own right should bring focus to this period of care.

Recent trends in the development of vitamin B12 derivatives for medicinal applications

This Feature Article highlights recent developments in the field of vitamin B12 derivatives for medicinal applications. The following topics are emphasized: (1) the development of aquacorrinoids for cyanide detection and detoxification, (2) the use of vitamin B12 conjugates and (3) antivitamins B12 for therapy and diagnosis, and (4) the design of corrinoids as activators of soluble guanylyl cyclase (sGC).

A prospective, randomized trial of intravenous hydroxocobalamin versus whole blood transfusion compared to no treatment for Class III hemorrhagic shock resuscitation in a prehospital swine model

OBJECTIVES

The objective was to compare systolic blood pressure (sBP) over time in swine that have had 30% of their blood volume removed (Class III shock) and treated with intravenous (IV) whole blood or IV hydroxocobalamin, compared to nontreated control animals.

METHODS

Thirty swine (45 to 55 kg) were anesthetized, intubated, and instrumented with continuous femoral and pulmonary artery pressure monitoring. Animals were hemorrhaged a total of 20 mL/kg over a 20-minute period. Five minutes after hemorrhage, animals were randomly assigned to receive 150 mg/kg IV hydroxocobalamin solubilized in 180 mL of saline, 500 mL of whole blood, or no treatment. Animals were monitored for 60 minutes thereafter. A sample size of 10 animals per group was determined based on a power of 80% and an alpha of 0.05 to detect an effect size of at least a 0.25 difference (>1 standard deviation) in mean sBP between groups. sBP values were analyzed using repeated-measures analysis of variance (RANOVA). Secondary outcome data were analyzed using repeated-measures multivariate analysis of variance (RMANOVA).

RESULTS

There were no significant differences between hemodynamic parameters of IV hydroxocobalamin versus whole blood versus control group at baseline (MANOVA; Wilks' lambda; p = 0.868) or immediately posthemorrhage (mean sBP = 47 mm Hg vs. 41 mm Hg vs. 37 mm Hg; mean arterial pressure = 39 mm Hg vs. 28 mm Hg vs. 34 mm Hg; mean serum lactate = 1.2 mmol/L vs. 1.4 mmol/L vs. 1.4 mmol/L; MANOVA; Wilks' lambda; p = 0.348). The outcome RANOVA model detected a significant difference by time between groups (p < 0.001). Specifically, 10 minutes after treatment, treated animals showed a significant increase in mean sBP compared to nontreated animals (mean sBP = 76.3 mm Hg vs. 85.7 mm Hg vs. 51.1 mm Hg; p < 0.001). RMANOVA modeling of the secondary data detected a significant difference in mean arterial pressure, heart rate, and serum lactate (p < 0.001). Similar to sBP, 10 minutes after treatment, treated animals showed a significant increase in mean arterial pressure compared to nontreated animals (mean arterial pressure = 67.7 mm Hg vs. 61.4 mm Hg vs. 40.5 mm Hg). By 10 minutes, mean heart rate was significantly slower in treated animals compared to nontreated animals (mean heart rate = 97.3 beats/min vs. 95.2 beats/min vs. 129.5 beats/min; p < 0.05). Serum lactate, an early predictor of shock, continued to rise in the control group, whereas it did not in treated animals. Thirty minutes after treatment, serum lactate values of treated animals were significantly lower compared to nontreated animals (p < 0.05). This trend continued throughout the 60-minute observation period such that 60-minute values for lactate were 1.4 mmol/L versus 1.1 mmol/L versus 3.8 mmol/L. IV hydroxocobalamin produced a statistically significant increase in systemic vascular resistance compared to control, but not whole blood, with a concomitant decrease in cardiac output.

CONCLUSIONS

Intravenous hydroxocobalamin was more effective than no treatment and as effective as whole blood transfusion, in reversing hypotension and inhibiting rises in serum lactate in this prehospital, controlled, Class III swine hemorrhage model.

Intraosseous versus intravenous infusion of hydroxocobalamin for the treatment of acute severe cyanide toxicity in a Swine model

OBJECTIVES

Easily administrated cyanide antidotes are needed for first responders, military troops, and emergency department staff after cyanide exposure in mass casualty incidents or due to smoke inhalation during fires involving many victims. Hydroxocobalamin has proven to be an effective antidote, but cannot be given intramuscularly because the volume of diluent needed is too large. Thus, intraosseous (IO) infusion may be an alternative, as it is simple and has been recommended for the administration of other resuscitation drugs. The primary objective of this study was to compare the efficacy of IO delivery of hydroxocobalamin to intravenous (IV) injection for the management of acute cyanide toxicity in a well-described porcine model.

METHODS

Twenty-four swine (45 to 55 kg) were anesthetized, intubated, and instrumented with continuous mean arterial pressure (MAP) and cardiac output monitoring. Cyanide was continuously infused until severe hypotension (50% of baseline MAP), followed by IO or IV hydroxocobalamin treatment. Animals were randomly assigned to receive IV (150 mg/kg) or IO (150 mg/kg) hydroxocobalamin and monitored for 60 minutes after start of antidotal infusion. The primary outcome measure was the change in MAP after antidotal treatment from onset of hypotension (time zero) to 60 minutes. A sample size of 12 animals per group was determined by group size analysis based on power of 80% to detect a one standard deviation of the mean MAP between the groups with an alpha of 0.05. Whole blood cyanide, lactate, pH, nitrotyrosine (nitric oxide marker) levels, cerebral and renal near infrared spectrometry (NIRS) oxygenation, and inflammatory markers were also measured. Repeated-measures analysis of variance was used to determine statistically significant changes between groups over time.

RESULTS

At baseline and at the point of hypotension, physiologic parameters were similar between groups. At the conclusion of the study, 10 out of 12 animals in the IV group and 10 out of 12 in IO group survived (p = 1.0). Both groups demonstrated a similar return to baseline MAP (p = 0.997). Cardiac output, oxygen saturation, and systemic vascular resistance were also found to be similar between groups (p > 0.4), and no difference was detected between bicarbonate, pH, and lactate levels (p > 0.8). Cyanide levels were undetectable after the hydroxocobalamin infusion throughout the study in both groups (p = 1.0). Cerebral and renal NIRS oxygenation decreased in parallel to MAP during cyanide infusion and increased after antidote infusion in both groups. Serum nitrotyrosine increased during cyanide infusion in all animals and then decreased in both study arms after hydroxocobalamin infusion (p > 0.5). Serum cytokines increased starting at cyanide infusion and no difference was detected between groups (tumor necrosis factor-α, interleukin [IL]-1β, IL-6, and IL-10).

CONCLUSIONS

The authors found no difference in the efficacy of IV versus IO hydroxocobalamin in the treatment of severe cyanide toxicity in a validated porcine model.

Initial assessment and fluid resuscitation of burn patients

For the physician or surgeon practicing outside the confines of a burn center, initial assessment and fluid resuscitation will encompass most of his or her exposure to patients with severe burns. The importance of this phase of care should not be underestimated. This article provides a review of how to perform initial resuscitation of patients with significant burns and/or inhalation injury, while arranging for transfer to a regional burn center.

In vivo interactions between cobalt or ferric compounds and the pools of sulphide in the blood during and after H2S poisoning

Hydrogen sulphide (H2S), a chemical hazard in oil and gas production, has recently become a dreadful method of suicide, posing specific risks and challenges for the first responders. Currently, there is no proven effective treatment against H2S poisoning and its severe neurological, respiratory or cardiac after-effects. We have recently described that H2S is present in various compartments, or pools, in the body during sulphide exposure, which have different levels of toxicity. The general goals of our study were to (1) determine the concentrations and kinetics of the various pools of hydrogen sulphide in the blood, i.e., gaseous (CgH2S) versus total sulphide, i.e., reacting with monobromobimane (CMBBH2S), during and following H2S exposure in a small and large mammal and (2) establish the interaction between the pools of H2S and a methemoglobin (MetHb) solution or a high dose of hydroxocobalamin (HyCo). We found that CgH2S during and following H2S infusion was similar in sedated sheep and rats at any given rate of infusion/kg and provoked symptoms, i.e., hyperpnea and apnea, at the same CgH2S. After H2S administration was stopped, CgH2S disappeared within 1 min. CMBBH2S also dropped to 2-3μM, but remained above baseline levels for at least 30 min. Infusion of a MetHb solution during H2S infusion produced an immediate reduction in the free/soluble pool of H2S only, whereas CMBBH2S increased by severalfold. HyCo (70 mg/kg) also decreased the concentrations of free/soluble H2S to almost zero; CgH2S returned to pre-HyCo levels within a maximum of 20 min, if H2S infusion is maintained. These results are discussed in the context of a relevant scenario, wherein antidotes can only be administered after H2S exposure.

Report on a study of fires with smoke gas development : determination of blood cyanide levels, clinical signs and laboratory values in victims

BACKGROUND

This is a report on an international non-interventional study of patients exposed to fires with smoke development in closed rooms. The objective of the study was to document clinical symptoms, relevant laboratory values and blood cyanide concentrations from fire victims in order to confirm or rule out presumptive correlations between the individual parameters.

MATERIALS AND METHODS

The study was conducted in five European countries with patients being included if they presented with the characteristic clinical signs, such as soot deposits and altered neurological status. Venous blood samples were taken from victims prior to administration of an antidote in all cases and determination of cyanide concentration was performed in a central laboratory using high performance liquid chromatography.

RESULTS

Data from 102 patients (62 % male, average age 49 years) were included in the evaluation with no blood samples being available for analysis from 2 patients. In 25 patients the blood cyanide concentration was below the limit of detection of 1.2 μmol/l. Cyanide levels between 1.2 and 10 μmol/l were measured in 54 patients, 7 patients had values between 10 and 20 μmol/l, 4 patients between 20 and 40 μmol/l while levels above 40 μmol/l were determined in 10 patients. The results of the study could not demonstrate that the cyanide level was influenced either by the interval between smoke exposure and blood sampling or the duration presence at the fire scene. The following clinical signs or laboratory values were recorded as relevant for increased and possibly toxic cyanide levels: respiratory arrest, dyspnea, resuscitation requirement, tracheal intubation, respiratory support measures, low Glasgow coma scale (GCS) score and respiratory frequency. A correlation between cyanide concentration and the total amount of soot deposits on the face and neck, in the oral cavity and in expectoration was confirmed. A correlation between cyanide and carboxyhemoglobin (COHb) levels in the blood of fire victims was also confirmed.

CONCLUSIONS

As long as it is not possible to immediately determine the blood cyanide concentration in patients exposed to fire with smoke development, a decreased GCS score, soot deposits particularly in expectoration, dyspnea and convulsions are to be regarded as risk markers for intoxication. In their presence immediate administration of hydroxocobalamin as an antidote is recommended.

Effect of hydroxocobalamin on surface oximetry in nonexposed humans

INTRODUCTION

The newer cyanide antidote, hydroxocobalamin, due to its pigmentation, has been found to cause interferences in some laboratory assays. Co-oximetry may also be affected by hydroxocobalamin, leading to false elevations in hemoglobin concentration, methemoglobin, carboxyhemoglobin, and false decreases in oxyhemoglobin. The Masimo Radical-7 is a medical device that performs noninvasive oximetry and estimates hemoglobin (Hb) concentration and percent carboxyhemoglobin (COHb), methemoglobin (MetHb), and oxyhemoglobin saturation (O2Hb).

STUDY OBJECTIVES

The study sought to determine the effect of hydroxocobalamin on noninvasive measurement of hemoglobin indices using the Masimo Radical-7 monitor.

METHODS

Seven asymptomatic volunteers who were unexposed to cyanide had baseline heart rate (HR), blood pressure (BP), and oximeter measurements recorded followed by an infusion of five grams of hydroxocobalamin over 15 minutes. The above parameters were subsequently recorded at: 5, 10, 15, 30 and 60 minutes post infusion. Data were analyzed by calculating the area under the curve (AUC) for each variable and comparing the results to expected values by paired t tests. Expected AUC values were calculated by extrapolating baseline values across the entire time period.

RESULTS

The mean differences from baseline values with 95% confidence intervals and t tests of mean difference were: SBP: 11 mm Hg (95% CI, 0-22; P = .051); HR: -9 (95% CI, -15 to -3; P = .01); Hb: -0.1 (95% CI, -0.7 to 0.4; P = .57); O2Hb: 0 g/dL (95% CI, -1 to 1; P = .41); COHb: -1 (95% CI, -3 to 1; P = .25); MetHb: -0.2 (95% CI, -0.3 to 0; P = .03).

DISCUSSION

After infusion of hydroxocobalamin there was a significant elevation of systolic blood pressure and decrease in heart rate. There were no significant differences in Hb, O2Hb, and COHb. Although percent methemoglobin concentrations were statistically lower, the authors feel this difference is of trivial clinical significance.

CONCLUSION

The administration of hydroxocobalamin does not significantly impact noninvasive oximetry.

Hydroxocobalamin in cyanide poisoning

INTRODUCTION

On theoretical grounds, hydroxocobalamin is an attractive antidote for cyanide poisoning as cobalt compounds have the ability to bind and detoxify cyanide. This paper reviews the pharmacokinetic and pharmacodynamic aspects of hydroxocobalamin, its efficacy in human cyanide poisoning and its adverse effects.

METHODS

PubMed was searched for the period 1952 to April 2012. A total of 71 papers were identified in this way; and none was excluded. PHARMACOKINETICS AND PHARMACODYNAMICS: Pharmacokinetic studies in dogs and humans suggest a two-compartment model, with first order elimination kinetics. Pharmacodynamic studies in animals suggest that hydroxocobalamin would be a satisfactory antidote for human cyanide poisoning. EFFICACY IN HUMAN POISONING: There is limited evidence that hydroxocobalamin alone is effective in severe poisoning by cyanide salts. The evidence for the efficacy of hydroxocobalamin in smoke inhalation is complicated by lack of evidence for the importance of cyanide exposure in fires and the effects of other chemicals as well as confounding effects of other therapeutic measures, including hyperbaric oxygen. Evidence that hydroxocobalamin is effective in poisoning due to hydrogen cyanide alone is lacking; extrapolation of efficacy from poisoning by ingested cyanide salts may not be valid. The rate of absorption may be greater with inhaled hydrogen cyanide and the recommended slow intravenous administration of hydroxocobalamin may severely limit its clinical effectiveness in these circumstances.

ADVERSE EFFECTS

Both animal and human data suggest that hydroxocobalamin is lacking in clinically significant adverse effects. However, in one human volunteer study, delayed but prolonged rashes were observed in one-sixth of subjects, appearing 7 to 25 days after administration of 5 g or more of hydroxocobalamin. Rare adverse effects have included dyspnoea, facial oedema, and urticaria.

CONCLUSIONS

Limited data on human poisonings with cyanide salts suggest that hydroxocobalamin is an effective antidote; data from smoke inhalation are less clear-cut. Although clinically important reactions to hydroxocobalamin have not been seen, some, non-life threatening, adverse reactions can occur.

Isolated inhalational injury: Clinical course and outcomes in a multidisciplinary intensive care unit

Background and Aims:

Although smoke inhalation is well known to cause acute lung injury, there are few reports in literature that study the evolution, clinical course and outcomes of isolated inhalational lung injury in a modern intensive care setting. A major fire disaster provided us the opportunity to study victims of isolated inhalational injury admitted to our Multidisciplinary Intensive Care Unit (MICU).

Materials and Methods:

We studied the clinical course, ICU and hospital outcomes of 13 victims of a fire disaster who required mechanical ventilation for isolated inhalational lung injury. All patients were followed up at regular intervals, and their functional status was assessed at 8 months after hospital discharge.

Results:

The Lung Injury Scores (LIS) worsened to reach a nadir on Day 3 of injury. There was a significant correlation between the LIS on Day 3 and duration of mechanical ventilation (r = 0.8; P = 0.003), ICU (r = 0.8; P = 0.002) and hospital (r = 0.6; P = 0.02) days. Late-onset airway complications were encountered in four patients. Three of them required long-term artificial airways – two with a tracheostomy while the third patient required surgical insertion of a “T” tube. Persistent problems with phonation occurred in two patients. At 8 months postdischarge, all patients were independent with activities of daily living; all were back to work, except for two who continued to need artificial airways.

Conclusions:

Inhalational lung injury progresses over the first few days and is worst after 72 h. Late-onset airway complications may manifest after several weeks and require repeated intervention.

Antidotes for toxicological emergencies: a practical review

PURPOSE

Appropriate therapies for commonly encountered poisonings, medication overdoses, and other toxicological emergencies are reviewed, with discussion of pharmacists' role in ensuring their ready availability and proper use.

SUMMARY

Poisoning is the second leading cause of injury-related morbidity and mortality in the United States, with more than 2.4 million toxic exposures reported each year. Recently published national consensus guidelines recommend that hospitals providing emergency care routinely stock 24 antidotes for a wide range of toxicities, including toxic-alcohol poisoning, exposure to cyanide and other industrial agents, and intentional or unintentional overdoses of prescription medications (e.g., calcium-channel blockers, β-blockers, digoxin, isoniazid). Pharmacists can help reduce morbidity and mortality due to poisonings and overdoses by (1) recognizing the signs and symptoms of various types of toxic exposure, (2) guiding emergency room staff on the appropriate use of antidotes and supportive therapies, (3) helping to ensure appropriate monitoring of patients for antidote response and adverse effects, and (4) managing the procurement and stocking of antidotes to ensure their timely availability.

CONCLUSION

Pharmacists can play a key role in reducing poisoning and overdose injuries and deaths by assisting in the early recognition of toxic exposures and guiding emergency personnel on the proper storage, selection, and use of antidotal therapies.

Empiric management of cyanide toxicity associated with smoke inhalation

Enclosed-space smoke inhalation is the fifth most common cause of all unintentional injury deaths in the United States. Increasingly, cyanide has been recognized as a significant toxicant in many cases of smoke inhalation. However, it cannot be emergently verified. Failure to recognize the possibility of cyanide toxicity may result in inadequate treatment. Findings suggestive cyanide toxicity include: (1) a history of an enclosed-space fire scene in which smoke inhalation was likely; (2) the presence of oropharyngeal soot or carbonaceous expectorations; (3) any alteration of the level of consciousness, and particularly, otherwise inexplicable hypotension (systolic blood pressure ≤90 mmHg in adults). Prehospital studies have demonstrated the feasibility and safety of empiric treatment with hydroxocobalamin for patients with suspected smoke inhalation cyanide toxicity. Although United States Food and Drug Administration (FDA)-approved since 2006, the lack of efficacy data has stymied the routine use of this potentially lifesaving antidote. Based on a literature review and on-site observation of the Paris Fire Brigade, emergency management protocols to guide empiric and early hydroxocobalamin administration in smoke inhalation victims with high-risk presentations are proposed.