Utility and outcomes of hydroxocobalamin use in smoke inhalation patients

Inhalation Injury, Respiratory Failure, and Ventilator Support in Acute Burn Care

Sustaining an inhalation injury increases the risk of severe complications and mortality. Current evidential support to guide treatment of the injury or subsequent complications is lacking, as studies either exclude inhalation injury or design limit inferences that can be made. Conventional ventilator modes are most commonly used, but there is no consensus on optimal strategies. Settings should be customized to patient tolerance and response. Data for pharmacotherapy adjunctive treatments are limited.

Evaluation of hydroxocobalamin use for the treatment of suspected cyanide toxicity secondary to smoke inhalation

Hydroxocobalamin is used for cyanide toxicity after smoke inhalation, but diagnosis is challenging. Retrospective studies have associated hydroxocobalamin with acute kidney injury (AKI). This is a retrospective analysis of patients receiving hydroxocobalamin for suspected cyanide toxicity. The primary outcome was the proportion of patients meeting predefined appropriate use criteria defined as ≥1 of the following: serum lactate ≥8 mmol/L, systolic blood pressure (SBP) <90 mmHg, new-onset seizure, cardiac arrest, or respiratory arrest. Secondary outcomes included incidence of AKI, pneumonia, resolution of initial neurologic symptoms, and in-hospital mortality. Forty-six patients were included; 35 (76%) met the primary outcome. All met appropriate use criteria due to respiratory arrest, 15 (43%) for lactate, 14 (40%) for SBP, 12 (34%) for cardiac arrest. AKI, pneumonia, and resolution of neurologic symptoms occurred in 30%, 21%, and 49% of patients, respectively. In-hospital mortality was higher in patients meeting criteria, 49% vs. 9% (95% CI 0.16, 0.64). When appropriate use criteria were modified to exclude respiratory arrest in a post-hoc analysis, differences were maintained, suggesting respiratory arrest alone is not a critical component to determine hydroxocobalamin administration. Predefined appropriate use criteria identify severely ill smoke inhalation victims and provides hydroxocobalamin treatment guidance.

Choosing wisely in burn care

BACKGROUND

The Choosing Wisely Campaign was launched in 2012 and has been applied to a broad spectrum of disciplines in almost thirty countries, with the objective of reducing unnecessary or potentially harmful investigations and procedures, thus limiting costs and improving outcomes. In Canada, patients with burn injuries are usually initially assessed by primary care and emergency providers, while plastic or general surgeons provide ongoing management. We sought to develop a series of Choosing Wisely statements for burn care to guide these practitioners and inform suitable, cost-effective investigations and treatment choices.

METHODS

The Choosing Wisely Canada list for Burns was developed by members of the Canadian Special Interest Group of the American Burn Association. Eleven recommendations were generated from an initial list of 29 statements using a modified Delphi process and SurveyMonkey™.

RESULTS

Recommendations included statements on avoidance of prophylactic antibiotics, restriction of blood products, use of adjunctive analgesic medications, monitoring and titration of opioid analgesics, and minimizing 'routine' bloodwork, microbiology or radiological investigations.

CONCLUSIONS

The Choosing Wisely recommendations aim to encourage greater discussion between those involved in burn care, other health care professionals, and their patients, with a view to reduce the cost and adverse effects associated with unnecessary therapeutic and diagnostic procedures, while still maintaining high standards of evidence-based burn care.

Care of the Critically Injured Burn Patient

Care of the critically injured burn patient presents unique challenges to the intensivist. Certified burn centers are rare and geographically sparse, necessitating that much of the initial management of patients with severe burn injuries must happen in the pre-burn center setting.1 Severe burn injuries often lead to a wide range of complications that extend beyond the loss of skin integrity and require specialized care. As such, medical intensivists are often called upon to stabilize these critically injured patients. This focused review outlines the clinical care of these medically complex patients, including airway management, post-burn complications, volume resuscitation, nutrition, and end-of-life care.

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.

Intraosseous administration of hydroxocobalamin after enclosed structure fire cardiac arrest

Smoke inhalation is the most common cause of acute cyanide poisoning in the developed world. Hydroxocobalamin is an antidote for cyanide poisoning. There is little published about human intraosseous antidote administration. We present a case of intraosseous hydroxocobalamin administration in an adult smoke inhalation victim, found in cardiac arrest inside her burning manufactured home. Return of spontaneous circulation was achieved after 20 min of cardiopulmonary resuscitation. Five grams of hydroxocobalamin were subsequently given intraosseously. On hospital arrival, patient was found to have a respiratory-metabolic acidosis. She had red-coloured urine without haematuria, a known sequela of hydroxocobalamin administration. Patient's neurological status deteriorated, and she died 4 days after admission. This case highlights that intraosseously administered hydroxocobalamin seems to adequately flow into the marrow cavity and enter the circulatory system despite the non-compressible glass antidote vial. This appears to be only the second reported human case of intraosseous hydroxocobalamin administration.

ABC's of Vitamin Supplementation in Critical Illness

Critical illness commonly presents as a systemic inflammatory process. Through this inflammation, there is an enhanced production of reactive oxygen and nitrogen species combined with marked reductions in protective plasma antioxidant concentrations. This imbalance is referred to as oxidative stress and is commonly encountered in numerous disease states in the critically ill including sepsis, trauma, acute respiratory distress syndrome, and burns. Oxidative stress can lead to cellular, tissue and organ damage as well as increased morbidity and mortality in critically ill patients. Supplementation with exogenous micronutrients to restore balance and antioxidant concentrations in critically ill patients has been considered for several decades. It is proposed that antioxidant vitamins, such as vitamins A and C, may minimize oxidative stress and improve clinical outcomes. Vitamin B formulations may play a role in curtailing lactic acidosis and are recently being evaluated as an acute phase reactant. However, few large, randomized trials specifically investigating the role of vitamin supplementation in the critically ill patient population are available. This article seeks to review recently published literature surrounding the role of supplementation of vitamins A, B and C in critically ill patients.

Initial management of severe burn injury

PURPOSE OF REVIEW

Patients with severe burn injuries pose significant challenges for the intensivist. Though average burn sizes have decreased over time, severe burn injuries involving greater than 20% of the total body surface area still occur. Verified burn centers are limited, making the management of severely burn injured patients at nonspecialized ICUs likely. Current practices in burn care have increased survivability even from massive burns. It is important for intensivists to be aware of the unique complications and therapeutic options in burn critical care management. This review critically discusses current practices and recently published data regarding the evaluation and management of severe burn injury.

RECENT FINDINGS

Burn patients have long, complex ICU stays with accompanying multiorgan dysfunction. Recent advances in burn intensive care have focused on acute respiratory distress syndrome from inhalation injury, acute kidney injury (AKI), and transfusion, resulting in new strategies for organ failure, including renal replacement therapy and extracorporeal life support.

SUMMARY

Initial evaluation and treatment of acute severe burn injury remains an ongoing area of study. This manuscript reviews current practices and considerations in the acute management of the severely burn injured patient.

A Review of the Most Impactful Published Pharmacotherapy-Pertinent Literature of 2017 and 2018 for Clinicians Caring for Patients with Burn or Inhalation Injuries

Staying current and evaluating literature related to pharmacotherapy in burn or inhalation injury can be difficult as burn care teams are multidisciplinary and pertinent content can be spread across a plethora of journals. The goal of this review is to critically evaluate recently published pharmacotherapy-pertinent literature, assist practitioners staying current, and better identify potential future research targets. Twelve board-certified clinical pharmacists with experience caring for patients with burn and inhalation injuries reviewed and graded scientific literature published in 2017 and 2018. An MeSH-based search revealed 1158 articles related to burns, which were published during the 2-year period. One-hundred fifty one were determined to be potentially related to pharmacotherapy. After exclusions, only 82 (7%) remained for scoring, and the top 10 comprehensively presented. More than half of the reviewed manuscripts were assessed as lacking a significant impact on pharmacotherapy. There is a need for higher impact literature to support pharmacotherapy-pertinent treatment of such complex patients.

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

Volume Resuscitation in Patients With High-Voltage Electrical Injuries

Volume resuscitation of patients with high-voltage electrical injuries (>1000 V) is a more complex challenge than standard burn resuscitation. High voltages penetrate deep tissues. These deep injuries are not accounted for in resuscitation formulae dependent on percentage of cutaneous burn. Myonecrosis occurring from direct electrical injury and secondary compartment syndromes can result in rhabdomyolysis, compromising renal function and urine output. Urine output is the primary end point, with a goal of 1 mL/kg/h for adult patients with high-voltage electrical injuries. As such, secondary resuscitation end points of laboratory values, such as lactate, base deficit, hemoglobin, and creatinine, as well as hemodynamic monitoring, such as mean arterial pressure and thermodilution techniques, can become crucial in guiding optimum administration of resuscitation fluids. Mannitol and bicarbonates are available but have limited support in the literature. High-voltage electrical injury patients often develop acute kidney injury requiring dialysis and have increased risks of chronic kidney disease and mortality. Continuous venovenous hemofiltration is a well-supported adjunct to clear the myoglobin load that hemodialysis cannot from circulation.

Modest and variable efficacy of pre-exposure hydroxocobalamin and dicobalt edetate in a porcine model of acute cyanide salt poisoning

Background: Dicobalt edetate and hydroxocobalamin are widely used to treat hydrogen cyanide poisoning. However, comparative and quantitative efficacy data are lacking. Although post-exposure treatment is typical, it may be possible to administer these antidotes before exposure to first attenders entering a known site of cyanide release, as supplementary protection to their personal protective equipment.Methods: We established an anaesthetised Gottingen minipig model of lethal bolus potassium cyanide (KCN) injection to simulate high dose hydrogen cyanide inhalation. Doses were similar to human lethal doses of KCN. Dicobalt edetate and hydroxocobalamin were administered shortly before KCN and their effect on metabolic and cardiovascular variables and survival time were measured.Results: Increases in arterial lactate were similar after 0.08 and 0.12 mmol/kg KCN. KCN 0.08 mmol/kg was survived by 4/4 animals with moderate cardiovascular effects, while the 0.12 mmol/kg dose was lethal in 4/4 animals, with a mean time to euthanasia of 28.3 (SEM: 13.9) min. Administration of dicobalt edetate (0.021 mmol/kg, 8.6 mg/kg) or hydroxocobalamin (0.054 mmol/kg, 75 mg/kg) at clinically licenced doses had modest effect on lactate concentrations but increased survival after administration of KCN 0.12 mmol/kg (survival: dicobalt edetate 4/4, hydroxocobalamin 2/4) but not 0.15 mmol/kg (0/4 and 0/4, respectively). In a subsequent larger study, doubling the dose of hydroxocobalamin (0.108 mmol/kg, 150 mg/kg) was associated with a modest but inconsistent increased survival after 0.15 mmol/kg KCN (survival: control 0/8, 75 mg/kg 1/10, 150 mg/kg 3/10) likely due to variable pharmacokinetics.Conclusions: In this porcine study of cyanide exposure, with pre-exposure antidote administration, licenced doses of dicobalt edetate and hydroxocobalamin were effective at just lethal doses but ineffective at less than twice the estimated LD₅₀. The efficacy of a rapidly-administered double-dose of hydroxocobalamin was limited by variable pharmacokinetics. In clinical poisoning scenarios, with delayed administration, the antidotes are likely to be even less effective. New antidotes are required for treatment of cyanide exposures appreciably above the minimum lethal dose.

Clinical chameleons: an emergency medicine focused review of carbon monoxide poisoning

Carbon monoxide (CO) is a colorless, odorless gas that is found in the environment, in the home, and in the human body as a normal part of mammalian metabolism. Poisoning from CO, a common exposure, is associated with significant morbidity and mortality if not recognized and treated in a timely manner. This review evaluates the signs and symptoms of CO poisoning, conditions that present similar to CO poisoning, and an approach to the recognition and management for CO poisoning. CO poisoning accounts for thousands of emergency department visits annually. If not promptly recognized and treated, it leads to significant morbidity and mortality. CO poisoning poses a challenge to the emergency physician because it classically presents with non-specific symptoms such as headache, dizziness, nausea, and vomiting. Due to nonspecific presentations, it is easily mistaken for other, more benign diagnoses such as viral infection. The use of specific historical clues such as exposure to non-conventional heat sources or suicide attempts in garages, as well as the use of targeted diagnostic testing with CO-oximetry, can confirm the diagnosis of CO poisoning. Once diagnosed, treatment options range from observation to the use of hyperbaric oxygen. CO poisoning is an elusive diagnosis. This review evaluates the signs and symptoms CO poisoning, common chameleons or mimics, and an approach to management of CO poisoning.

Smoke Inhalation Injury: Etiopathogenesis, Diagnosis, and Management

Smoke inhalation injury is a major determinant of morbidity and mortality in fire victims. It is a complex multifaceted injury affecting initially the airway; however, in short time, it can become a complex life-threatening systemic disease affecting every organ in the body. In this review, we provide a summary of the underlying pathophysiology of organ dysfunction and provide an up-to-date survey of the various critical care modalities that have been found beneficial in caring for these patients. Major pathophysiological change is development of edema in the respiratory tract. The tracheobronchial tree is injured by steam and toxic chemicals, leading to bronchoconstriction. Lung parenchyma is damaged by the release of proteolytic elastases, leading to release of inflammatory mediators, increase in transvascular flux of fluids, and development of pulmonary edema and atelectasis. Decreased levels of surfactant and immunomodulators such as interleukins and tumor-necrosis-factor-α accentuate the injury. A primary survey is conducted at the site of fire, to ensure adequate airway, breathing, and circulation. A good intravenous access is obtained for the administration of resuscitation fluids. Early intubation, preferably with fiberoptic bronchoscope, is prudent before development of airway edema. Bronchial hygiene is maintained, which involves therapeutic coughing, chest physiotherapy, deep breathing exercises, and early ambulation. Pharmacological agents such as beta-2 agonists, racemic epinephrine, N-acetyl cysteine, and aerosolized heparin are used for improving oxygenation of lungs. Newer agents being tested are perfluorohexane, porcine pulmonary surfactant, and ClearMate. Early diagnosis and treatment of smoke inhalation injury are the keys for better outcome.