Toxicology in the ICU: Part 2: specific toxins

Evaluation of high-dose insulin/euglycemia therapy for suspected β-blocker or calcium channel blocker overdose following guideline implementation

PURPOSE

High-dose insulin/euglycemia (HDIE) is targeted therapy for β-blocker and calcium channel blocker overdose. A guideline using concentrated insulin infusions (20 units/mL), aggressive monitoring, and supportive recommendations was implemented. We sought to evaluate safety before and after HDIE guideline implementation and describe the patient population, insulin doses, supplemental dextrose, vasopressor use, hospital and intensive care unit (ICU) lengths of stay, and mortality.

METHODS

Retrospective review was performed of patients receiving HDIE before and after guideline implementation at an academic medical center and community hospital from March 2011 through December 2019. Information on patient and overdose demographics, ingestion data, vital signs, interventions, adverse events, and disposition was collected. Data are presented descriptively with comparisons using Mann-Whitney U analysis and Fisher's exact tests.

RESULTS

During the study period, 27 patients were treated with HDIE, 10 before guideline implementation (37%; mean [SD] initial insulin dose, 0.49 [0.35] units/kg/h; mean [SD] maximum insulin dose, 2.25 [3.29] units/kg/h; median [interquartile range] duration, 10 [5.5-18.75] hours) and 17 after guideline implementation (63%; mean [SD] initial insulin dose, 1.01 [0.34] units/kg/h; mean [SD] maximum insulin dose, 2.99 [5.05] unit/kg/h; median [interquartile range] duration, 16 [11.5-37] hours). Hypoglycemia, hypokalemia, and volume overload occurred in 80% vs 29% (P = 0.018), 40% vs 53% (P = 0.69), and 50% vs 65% (P = 0.69) of patients in the preguideline vs postguideline group, respectively. Most patients received an initial insulin bolus (85%; mean [SD], 70.3 [21.8] units, 0.9 [0.26] units/kg) and vasopressor infusion (85%). More postguideline patients received a dextrose infusion with a concentration of 20% or higher (93% vs 50%, P = 0.015). There were no differences in cardiac arrest, in-hospital mortality, or hospital or ICU length of stay between the groups.

CONCLUSION

Hypoglycemia was reduced using an HDIE guideline and concentrated insulin.

Diagnosis of acute intoxications in critically ill patients: focus on biomarkers - part 2: markers for specific intoxications

In medical intensive care units, acute intoxications contribute to a large proportion of all patients. Epidemiology and a basic overview on this topic were presented in part one. The purpose of this second part regarding toxicological biomarkers in the ICU setting focuses on specific poisons and toxins. Following the introduction of anion and osmol gap in part one, it's relevance in toxic alcohols and other biomarkers for these poisonings are presented within this publication. Furthermore, the role of markers in the blood, urine and cerebrospinal fluid for several intoxications is evaluated. Specific details are presented, amongst others, for cardiovascular drug poisoning, paracetamol (acetaminophen), ethanol, pesticides, ricin and yew tree intoxications. Detailed biomarkers and therapeutic decision tools are shown for carbon monoxide (CO) and cyanide (CN^-) poisoning. Also, biomarkers in environmental toxicological situations such as mushroom poisoning and scorpion stings are presented.

Diagnosis of acute intoxications in critically ill patients: focus on biomarkers - part 1: epidemiology, methodology and general overview

Acute intoxications account for a significant proportion of the patient population in intensive care units and sedative medications, ethanol, illicit drugs, inhalable poisons and mixed intoxications are the most common causes. The aim of this article is to describe biomarkers for screening and diagnosis of acute intoxications in critically ill patients. For this purpose, a survey of the relevant literature was conducted, and guidelines, case reports, expert assessments, and scientific publications were reviewed. In critical care, it should always be attempted to identify and quantify the poison or toxin with the assistance of enzyme immunoassay (EIA), chromatography, and mass spectrometry techniques and this section is critically appraised in this publication. The principles for anion gap, osmol gap and lactate gap and their usage in intoxications is shown. Basic rules in test methodology and pre-analytics are reviewed. Biomarkers in general are presented in part one and biomarkers for specific intoxications including ethanol, paracetamol, cardiovascular drugs and many others are presented in part two of these publications.

Unusual complications from amitriptyline intoxication

Althoughtricyclic antidepressants(TCAs) are frequently prescribed to patients with depression, these drugs can also be misused. A 21-year-old comatose patient was referred to our hospital presenting with ventricular tachycardia. Despite initial treatment including intravascular lipid emulsion, ventricular fibrillation occurred soon after arrival. Venoarterial extracorporeal membrane oxygenation and therapeutic hypothermia were administered. Refractory arrhythmia disappeared on the next day. A high concentration of amitriptyline was identified in his blood samples on arrival. Mechanical bowel obstruction followed after abdominal compartment syndrome caused by anticholinergic effects, and refractory seizure occurred due to TCA intoxication. Although seizure was brought under control with anticonvulsant agents, his Glasgow Coma Scale did not recover to the full score. MRI presented irreversible damage to the bilateral frontal lobe and insula. Amitriptyline has the potential to cause unusual serious complications, such as abdominal compartment syndrome, irreversible central nervous system disability and lethal arrhythmia.

Neurologic Complications in the Intensive Care Unit

Complications involving the central and peripheral nervous system are frequently encountered in critically ill patients. All components of the neuraxis can be involved including the brain, spinal cord, peripheral nerves, neuromuscular junction, and muscles. Neurologic complications adversely impact outcome and length of stay. These complications can be related to underlying critical illness, pre-existing comorbid conditions, and commonly used and life-saving procedures and medications. Familiarity with the myriad neurologic complications that occur in the intensive care unit can facilitate their timely recognition and treatment. Additionally, awareness of treatment-related neurologic complications may inform decision-making, mitigate risk, and improve outcomes.

Assistance of inhalation injury victims caused by fire in confined spaces: what we learned from the tragedy at Santa Maria

On January 2013, a disaster at Santa Maria (RS) due to a fire in a confined space caused 242 deaths, most of them by inhalation injury. On November 2013, four individuals required intensive care following smoke inhalation from a fire at the Memorial da América Latina in São Paulo (SP). The present article reports the clinical progression and management of disaster victims presenting with inhalation injury. Patients ERL and OC exhibited early respiratory failure, bronchial aspiration of carbonaceous material, and carbon monoxide poisoning. Ventilation support was performed with 100% oxygen, the aspirated material was removed by bronchoscopy, and cyanide poisoning was empirically treated with sodium nitrite and sodium thiosulfate. Patient RP initially exhibited cough and retrosternal burning and subsequently progressed to respiratory failure due to upper airway swelling and early-onset pulmonary infection, which were treated with protective ventilation and antimicrobial agents. This patient was extubated following improvement of edema on bronchoscopy. Patient MA, an asthmatic, exhibited carbon monoxide poisoning and bronchospasm and was treated with normobaric hyperoxia, bronchodilators, and corticosteroids. The length of stay in the intensive care unit varied from four to 10 days, and all four patients exhibited satisfactory functional recovery. To conclude, inhalation injury has a preponderant role in fires in confined spaces. Invasive ventilation should not be delayed in cases with significant airway swelling. Hyperoxia should be induced early as a therapeutic means against carbon monoxide poisoning, in addition to empiric pharmacological treatment in suspected cases of cyanide poisoning.

Inhalation injury: epidemiology, pathology, treatment strategies

Lung injury resulting from inhalation of smoke or chemical products of combustion continues to be associated with significant morbidity and mortality. Combined with cutaneous burns, inhalation injury increases fluid resuscitation requirements, incidence of pulmonary complications and overall mortality of thermal injury. While many products and techniques have been developed to manage cutaneous thermal trauma, relatively few diagnosis-specific therapeutic options have been identified for patients with inhalation injury. Several factors explain slower progress for improvement in management of patients with inhalation injury. Inhalation injury is a more complex clinical problem. Burned cutaneous tissue may be excised and replaced with skin grafts. Injured pulmonary tissue must be protected from secondary injury due to resuscitation, mechanical ventilation and infection while host repair mechanisms receive appropriate support. Many of the consequences of smoke inhalation result from an inflammatory response involving mediators whose number and role remain incompletely understood despite improved tools for processing of clinical material. Improvements in mortality from inhalation injury are mostly due to widespread improvements in critical care rather than focused interventions for smoke inhalation.

Morbidity associated with inhalation injury is produced by heat exposure and inhaled toxins. Management of toxin exposure in smoke inhalation remains controversial, particularly as related to carbon monoxide and cyanide. Hyperbaric oxygen treatment has been evaluated in multiple trials to manage neurologic sequelae of carbon monoxide exposure. Unfortunately, data to date do not support application of hyperbaric oxygen in this population outside the context of clinical trials. Cyanide is another toxin produced by combustion of natural or synthetic materials. A number of antidote strategies have been evaluated to address tissue hypoxia associated with cyanide exposure. Data from European centers supports application of specific antidotes for cyanide toxicity. Consistent international support for this therapy is lacking. Even diagnostic criteria are not consistently applied though bronchoscopy is one diagnostic and therapeutic tool. Medical strategies under investigation for specific treatment of smoke inhalation include beta-agonists, pulmonary blood flow modifiers, anticoagulants and antiinflammatory strategies. Until the value of these and other approaches is confirmed, however, the clinical approach to inhalation injury is supportive.

Sedation for critically ill or injured adults in the intensive care unit: a shifting paradigm

As most critically ill or injured patients will require some degree of sedation, the goal of this paper was to comprehensively review the literature associated with use of sedative agents in the intensive care unit (ICU). The first and selected latter portions of this article present a narrative overview of the shifting paradigm in ICU sedation practices, indications for uninterrupted or prolonged ICU sedation, and the pharmacology of sedative agents. In the second portion, we conducted a structured, although not entirely systematic, review of the available evidence associated with use of alternative sedative agents in critically ill or injured adults. Data sources for this review were derived by searching OVID MEDLINE and PubMed from their first available date until May 2012 for relevant randomized controlled trials (RCTs), systematic reviews and/or meta-analyses and economic evaluations. Advances in the technology of mechanical ventilation have permitted clinicians to limit the use of sedation among the critically ill through daily sedative interruptions or other means. These practices have been reported to result in improved mortality, a decreased length of ICU and hospital stay and a lower risk of drug-associated delirium. However, in some cases, prolonged or uninterrupted sedation may still be indicated, such as when patients develop intracranial hypertension following traumatic brain injury. The pharmacokinetics of sedative agents have clinical importance and may be altered by critical illness or injury, co-morbid conditions and/or drug-drug interactions. Although use of validated sedation scales to monitor depth of sedation is likely to reduce adverse events, they have no utility for patients receiving neuromuscular receptor blocking agents. Depth of sedation monitoring devices such as the Bispectral Index (BIS©) also have limitations. Among existing RCTs, no sedative agent has been reported to improve the risk of mortality among the critically ill or injured. Moreover, although propofol may be associated with a shorter time to tracheal extubation and recovery from sedation than midazolam, the risk of hypertriglyceridaemia and hypotension is higher with propofol. Despite dexmedetomidine being linked with a lower risk of drug-associated delirium than alternative sedative agents, this drug increases risk of bradycardia and hypotension. Among adults with severe traumatic brain injury, there are insufficient data to suggest that any single sedative agent decreases the risk of subsequent poor neurological outcomes or mortality. The lack of examination of confounders, including the type of healthcare system in which the investigation was conducted, is a major limitation of existing pharmacoeconomic analyses, which likely limits generalizability of their results.

Resuscitation in a multiple casualty event

A major weakness in the emergency medical response to multiple casualty events continues to be the resuscitation component, which should consist of the systematic application of basic, advanced, and prolonged life support and definitive care within 24 hours. There have been major advances in emergency medical care over the last decade, including the feasibility of point-of-care ultrasound to aid in rapid assessment of injuries in the field, damage control resuscitation, and resuscitative surgery protocols, delivered by small trauma/resuscitation teams equipped with regional anesthesia capability for rapid deployment. Widespread adoption of these best practices may improve the delivery of resuscitative care in future multiple casualty events.

Delayed-onset seizure and cardiac arrest after amitriptyline overdose, treated with intravenous lipid emulsion therapy

In recent years, intravenous lipid emulsion (ILE) therapy has emerged as a new rescue antidote for treatment of certain toxicities, including cyclic antidepressants, and as the primary treatment of toxic manifestations after local anesthetic exposure. We present a case of a 13-year-old girl who developed delayed seizures and cardiac arrest after amitriptyline ingestion. As part of the treatment, she was treated with ILE therapy. The patient's laboratories were not interpretable for several hours after the lipid emulsion. The patient developed pancreatitis after the ILE therapy. This case is unique; not only is it one of the first reported cases of lipid emulsion being used in a pediatric patient, but in that the patient developed delayed toxicity and iatrogenic harm from the ILE.

Toxicology in the ICU: part 3: natural toxins

This is the third article of a three-part series that reviews the care of poisoned patients in the ICU. This article focuses on natural toxins, such as heavy metals and those produced by plants, mushrooms, arthropods, and snakes. The first article discussed the general approach to the patient, including laboratory testing; the second article focused on specific toxic agents, grouped into categories.