Delayed salicylate toxicity with undetectable initial levels after large-dose aspirin ingestion

Prediction rule of supratherapeutic peak serum salicylate level in poisoning patients attending emergency departments

Background:

Analgesic poisoning is common in Hong Kong. Analgesics containing salicylate are easily available. Salicylate poisoning may be encountered in the daily practice of the accident and emergency department. The issue of routine salicylate screening was discussed in a number of articles, and the viewpoints of most authors were that routine salicylate screening was unnecessary.

Objectives:

The primary outcome is to explore the predictive factors of supratherapeutic peak serum salicylate level (>2.17 mmol/L) and delineate the role of routine screening serum salicylate level in poisoned patients attending the accident and emergency department.

Methods:

This is a retrospective cohort study. Poisoning cases presented to Hong Kong Poison Information Centre between 1 July 2008 and 31 October 2020 with serum salicylate level checked were included. The demographics, laboratory parameters and clinical outcomes were reviewed.

Results:

There were 8673 cases included with serum salicylate level checked, accounting for 17% of all poisoning cases. Sixty-six (0.76%) cases had supratherapeutic peak serum salicylate level and 11 (0.13%) of them were undeclared salicylate ingestion. Worse clinical outcomes were observed in cases with supratherapeutic peak serum salicylate level. Univariate analysis showed that tinnitus, hyperthermia, alkalaemia, metabolic acidosis, respiratory alkalosis and therapeutic use of aspirin were significantly associated with supratherapeutic peak serum salicylate level. Variables with p < 0.3 were entered into the backward stepwise logistic regression by likelihood ratio. A clinical prediction rule with three attributes (tinnitus, therapeutic use of aspirin and partial pressure of CO2 <5 kPa) was derived. It showed 100% sensitivity in internal validation.

Conclusion:

Serum salicylate level should be checked in poisoned patients with (1) tinnitus, (2) the therapeutic use of aspirin or (3) partial pressure of CO2 <5 kPa in arterial or venous blood gas. Routine salicylate screening remained a tool for clinicians not experienced in toxicology.

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.

Salicylate toxicity after undetectable serum salicylate concentration: a retrospective cohort study

BACKGROUND

Salicylates are usually rapidly absorbed and quickly measurable in serum. An undetectable serum salicylate concentration ([ASA]) may occur early after ingestion and may be interpreted as evidence of non-exposure and not repeated. Although cases of delayed salicylate detection are reported rarely, the risk factors associated with this phenomenon are not known.

RESEARCH QUESTION

What factors are associated with an early undetectable [ASA] in salicylate poisoning?

METHODS

Records from a single regional poison center were searched from 2002 to 2016 for cases of salicylate toxicity treated with bicarbonate and [ASA] > 30 mg/dL. Cases were excluded if initial [ASA] was obtained >4 h after presentation. Case information, serial [ASA], and outcomes were recorded and compared between groups.

RESULTS

A total of 313 records met all criteria with 11 initially undetectable [ASA] (3.5%) and 302 detectable [ASA] (96.5%). Time of first [ASA] occurred sooner in the undetectable [ASA] group (89 vs. 137 min, p = 0.011) while time to peak [ASA] was longer (640 vs. 321 min, p < .001). The longest interval between ingestion and undetectable [ASA] was 225 min. Peak [ASA] and reported mean ingested dose were similar in both groups (45 vs. 50 mg/dL, p = NS; 19.7 g vs. 32.9 g, p = NS). Coingestion of agents that delay gastric emptying were similar in both groups (18% [2/11] vs. 25% [76/302], p = NS, chi-square). Hemodialysis was performed in 9% (1/11) of undetectable [ASA] patients and 5.6% (17/302) of detectable [ASA] patients (p = NS, chi-square). A single death occurred in the entire cohort in a patient with an initially detectable [ASA].

DISCUSSION

In this series, a small but significant proportion (3.5%) of patients who developed [ASA] > 30 mg/dL had an initially undetectable [ASA]. Those with an undetectable [ASA] were measured earlier after ingestion with a longer time to peak [ASA]. However, neither coingestion of agents prolonging gastric emptying nor reported dose ingested was different between groups. Formulation was infrequently recorded but one undetectable [ASA] did ingest a non-enteric coated product. Limitations include the small number of patients with undetectable [ASA], use of single poison center data and partial data on co-ingestants and aspirin formulation.

CONCLUSIONS

[ASA] may be undetectable early after an overdose and need for serial [ASA] in the evaluation of salicylate ingestion should be further explored. Additional research is needed to determine any causative factors and the optimal timing of [ASA] measurements.

Delayed Salicylate Toxicity in a 17-Year-Old Girl With Initially Undetectable Salicylate Concentration 3.9 Hours After Ingestion

We report the case of a 17-year-old girl with a 126-mg/kg nonenteric coated aspirin ingestion with nontoxic salicylate concentrations at 1.5 and 3.9 hours postingestion, who developed tinnitus and vomiting an estimated 8 hours postingestion, and who was subsequently found to have a toxic salicylate concentration at 22.7 hours postingestion. This case, as well as previous cases of delayed aspirin therapy, may prompt providers to consider educating patients and their care providers regarding the need to return for further testing if symptoms, such as vomiting or tinnitus, develop after an aspirin ingestion.

The Role of Sodium Bicarbonate in the Management of Some Toxic Ingestions

Adverse reactions to commonly prescribed medications and to substances of abuse may result in severe toxicity associated with increased morbidity and mortality. According to the Center for Disease Control, in 2013, at least 2113 human fatalities attributed to poisonings occurred in the United States of America. In this article, we review the data regarding the impact of systemic sodium bicarbonate administration in the management of certain poisonings including sodium channel blocker toxicities, salicylate overdose, and ingestion of some toxic alcohols and in various pharmacological toxicities. Based on the available literature and empiric experience, the administration of sodium bicarbonate appears to be beneficial in the management of a patient with the above-mentioned toxidromes. However, most of the available evidence originates from case reports, case series, and expert consensus recommendations. The potential mechanisms of sodium bicarbonate include high sodium load and the development of metabolic alkalosis with resultant decreased tissue penetration of the toxic substance with subsequent increased urinary excretion. While receiving sodium bicarbonate, patients must be monitored for the development of associated side effects including electrolyte abnormalities, the progression of metabolic alkalosis, volume overload, worsening respiratory status, and/or worsening metabolic acidosis. Patients with oliguric/anuric renal failure and advanced decompensated heart failure should not receive sodium bicarbonate.

Hypercapnea and Acidemia despite Hyperventilation following Endotracheal Intubation in a Case of Unknown Severe Salicylate Poisoning

Salicylates are common substances for deliberate self-harm. Acute salicylate toxicity is classically associated with an initial respiratory alkalosis, followed by an anion gap metabolic acidosis. The respiratory alkalosis is achieved through hyperventilation, driven by direct stimulation on the respiratory centers in the medulla and considered as a compensatory mechanism to avoid acidemia. However, in later stages of severe salicylate toxicity, patients become increasingly obtunded, with subsequent loss of airway reflexes, and therefore intubation may be necessary. Mechanical ventilation has been recommended against in acute salicylate poisoning, as it is believed to take away the compensatory hyperpnea and tachypnea. Despite the intuitive physiological basis for this recommendation, there is a paucity of evidence to support it. We describe a case of a 59-year-old male presenting with decreased level of consciousness and no known history of ingestion. He was intubated and experienced profound hypercarbia and acidemia despite mechanical ventilation with high minute ventilation and tidal volumes. This case illustrates the deleterious effects of intubation in severe salicylate toxicity.

Acute salicylate poisoning: risk factors for severe outcome

CONTEXT

Salicylate poisoning remains a significant public health threat with more than 20,000 exposures reported annually in the United States.

OBJECTIVE

We aimed to establish early predictors of severe in-hospital outcomes in Emergency Department patients presenting with acute salicylate poisoning.

METHODS

This was a secondary data analysis of adult salicylate overdoses from a prospective cohort study of acute drug overdoses at two urban university teaching hospitals from 2009 to 2013. Patients were included based on confirmed salicylate ingestion and enrolled consecutively. Demographics, clinical parameters, treatment and disposition were collected from the medical record. Severe outcome was defined as a composite occurrence of acidemia (pH <7.3 or bicarbonate <16 mEq/L), hemodialysis, and/or death.

RESULTS

Out of 1997 overdoses screened, 48 patients met inclusion/exclusion criteria. Patient characteristics were 43.8% male, median age 32 (range 18-87), mean initial salicylate concentration 28.1 mg/dL (SD 26.6), and 20.8% classified as severe outcome. Univariate analysis indicated that age, respiratory rate, lactate, coma, and the presence of co-ingestions were significantly associated with severe outcome, while initial salicylate concentration alone had no association. However, when adjusted for salicylate concentration, only age (OR 1.13; 95% CI 1.02-1.26) and respiratory rate (OR 1.29; 95% CI 1.02-1.63) were independent predictors. Additionally, lactate showed excellent test characteristics to predict severe outcome, with an optimal cutpoint of 2.25 mmol/L (78% sensitivity, 67% specificity).

CONCLUSIONS

In adult Emergency Department patients with acute salicylate poisoning, independent predictors of severe outcome were older age and increased respiratory rate, as well as initial serum lactate, while initial salicylate concentration alone was not predictive.

Adverse Drug Reactions in the Intensive Care Unit

Adverse drug reactions (ADRs) are undesirable effects of medications used in normal doses [1]. ADRs can occur during treatment in an intensive care unit (ICU) or result in ICU admissions. A meta-analysis of 4139 studies suggests the incidence of ADRs among hospitalized patients is 17% [2]. Because of underreporting and misdiagnosis, the incidence of ADRs may be much higher and has been reported to be as high as 36% [3]. Critically ill patients are at especially high risk because of medical complexity, numerous high-alert medications, complex and often challenging drug dosing and medication regimens, and opportunity for error related to the distractions of the ICU environment [4]. Table 1 summarizes the ADRs included in this chapter.

The Role of Renal Replacement Therapy in the Management of Pharmacologic Poisonings

Pharmacologic toxicities are common and range from mild to life-threatening. The aim of this study is to review and update the data on the role of renal replacement therapy (RRT) in the management of various pharmacologic poisonings. We aim to provide a focused review on the role of RRT in the management of pharmacological toxicities. Relevant publications were searched in MEDLINE with the following search terms alone or in combination: pharmacologic toxicity, hemodialysis, hemofiltration, renal replacement therapy, toxicology, poisonings, critical illness, and intensive care. The studies showed that a pharmacologic substance should meet several prerequisites to be deemed dialyzable. These variables include having a low molecular weight (<500 Da) and low degree of protein binding (<80%), being water-soluble, and having a low volume of distribution (<1 L/kg). RRT should be strongly considered in critically ill patients presenting with toxic alcohol ingestion, salicylate overdose, severe valproic acid toxicity, metformin overdose, and lithium poisoning. The role of RRT in other pharmacologic toxicities is less certain and should be considered on a case-by-case basis.

Late Metabolic Acidosis Caused by Renal Tubular Acidosis in Acute Salicylate Poisoning

A 16-year-old man was transferred to our emergency department seven hours after ingesting 486 aspirin tablets. His blood salicylate level was 83.7 mg/dL. He was treated with fluid resuscitation and sodium bicarbonate infusion, and his condition gradually improved, with a decline in the blood salicylate level. However, eight days after admission, he again reported nausea, a venous blood gas revealed metabolic acidosis with a normal anion gap. The blood salicylate level was undetectable, and a urinalysis showed glycosuria, proteinuria and elevated beta-2 microglobulin and n-acetyl glucosamine levels, with a normal urinary pH despite the acidosis. We diagnosed him with relapse of metabolic acidosis caused by renal tubular acidosis.

Arterial Blood Gases

Arterial blood gases (ABG) results reflect underlying pathology and interpretation of the results are often compounded by ongoing disease processes and clinical interventions. While ABG specimens should be analysed immediately for optimal results the Clinical and Laboratory Standards Institute (CLSI) has recommended a window of 30 minutes at room temperature from blood collection to ABG analysis. A fresh and simple approach to interpreting ABG is provided.

Sudden-onset tachypnea and confusion in a previously healthy teenager

Acute intoxication with acetylsalicylic acid is a severe event commonly seen in children resulting from wide availability of this drug without prescription. Cases of self-poisoning resulting from overdose continue to occur and, although far less common, they are often severe and life-threatening. We report a 14-year-old girl who presented to the emergency department with tachypnea and altered mental status as a result of acetylsalicylic acid overdose in a suicide attempt. We discuss her presentation and the pathophysiological considerations leading to the management decisions taken during her emergency department stay, highlighting the role of the clinician and therapeutic drug monitoring consultant. The use of rapid decontamination with multiple doses of charcoal, even when more than 4 hours have passed since ingestion, and the use of urinary alkalinization are stressed. Timely management can obviate the need for dialysis. Published cases of acetylsalicylic acid intoxication are reviewed.