Lack of toxicity from pediatric beta-blocker exposures

The risk of toxicity in a child who is unintentionally exposed to a beta-blocking drug remains uncertain. The current study further defines this risk, particularly in the common scenario of ingestion of one or two tablets. A prospective cohort of 208 pediatric patients, 6 months to 6 years of age, reported to two regional poison centers serves as the study population. Data were collected with a standardized instrument during the care of each patient and for a minimum of 24 hours after exposure. No instances of serious toxicity typical of beta-blocker intoxication, such as ‘shock-like’ states, arrhythmias or seizures were observed in this series. Furthermore, there were no reported episodes of hypoglycemia, symptomatic bradycardia or bronchospasm. Nine instances of altered mental status or behavioral changes were reported. All appeared to be minor in nature. The most serious outcome was charcoal aspiration during gastrointestinal decontamination. This study adds to a growing body of evidence suggesting that exposure to one or two beta-blocker tablets places children at very little, if any, risk of toxicity.

Do poison center triage guidelines affect healthcare facility referrals?

BACKGROUND

The purpose of this study was to determine the extent to which poison center triage guidelines influence healthcare facility referral rates for acute, unintentional acetaminophen-only poisoning and acute, unintentional adult formulation iron poisoning.

METHODS

Managers of US poison centers were interviewed by telephone to determine their center's triage threshold value (mg/kg) for acute iron and acute acetaminophen poisoning in 1997. Triage threshold values and healthcare facility referral rates were fit to a univariate logistic regression model for acetaminophen and iron using maximum likelihood estimation.

RESULTS

Triage threshold values ranged from 120-201 mg/kg (acetaminophen) and 16-61 mg/kg (iron). Referral rates ranged from 3.1% to 24% (acetaminophen) and 3.7% to 46.7% (iron). There was a statistically significant inverse relationship between the triage value and the referral rate for acetaminophen (p < 0.001) and iron (p = 0.0013). The model explained 31.7% of the referral variation for acetaminophen but only 4.1% of the variation for iron.

CONCLUSION

There is great variability in poison center triage values and referral rates for iron and acetaminophen poisoning. Guidelines can account for a meaningful proportion of referral variation. Their influence appears to be substance dependent. These data suggest that efforts to determine and utilize the highest, safe, triage threshold value could substantially decrease healthcare costs for poisonings as long as patient medical outcomes are not compromised.

Acute beta blocker overdose: factors associated with the development of cardiovascular morbidity

OBJECTIVE

To identify factors in exposures to beta blockers (beta-adrenergic receptor antagonists) that are associated with the development of cardiovascular morbidity and contribute to disposition decisions from the emergency department.

METHODS

Prospective cohort of 280 beta blocker exposures reported to 2 regional poison centers. Multiple logistic regression was used to determine association of various clinical factors and outcome.

RESULTS

In this series of beta blocker exposures, 41 (15%) developed cardiovascular morbidity and 4 (1.4%) died. A history of cardioactive coingestant was the only factor significantly associated with the development of cardiovascular morbidity (p < .05). When cases reporting cardioactive coingestants were excluded, a history of ingesting a beta blocker with membrane stabilizing activity was significantly associated with the development of cardiovascular morbidity (p < .05). All those in whom the timing of symptoms could be determined, developed symptoms within 6 hours of ingestion.

CONCLUSIONS

The single most important factor associated with the development of cardiovascular morbidity in beta blocker ingestion is a history of a cardioactive coingestant, primarily calcium channel blockers, cyclic antidepressants, and neuroleptics. In the absence of such coingestion, exposure to a beta blocker with membrane stabilizing activity is associated with an increased risk of cardiovascular morbidity. Beta blocker ingestion is unlikely to result in symptoms if the patient remains asymptomatic for 6 hours after the time of ingestion.

The effect of pulsed and sinusoidal magnetic fields on the morphology of developing chick embryos

Several investigators have reported robust, statistically significant results that indicate that weak (approximately 1 microT) magnetic fields (MFs) increase the rate of morphological abnormalities in chick embryos. However, other investigators have reported that weak MFs do not appear to affect embryo morphology at all. We present the results of experiments conducted over five years in five distinct campaigns spanning several months each. In four of the campaigns, exposure was to a pulsed magnetic field (PMF); and in the final campaign, exposure was to a 60 Hz sinusoidal magnetic field (MF). A total of over 2500 White Leghorn chick embryos were examined. When the results of the campaigns were analyzed separately, a range of responses was observed. Four campaigns (three PMF campaigns and one 60 Hz campaign) exhibited statistically significant increases (P > or = 0.01), ranging from 2-fold to 7-fold, in the abnormality rate in MF-exposed embryos. In the remaining PMF campaign, there was only a slight (roughly 50%), statistically insignificant (P = 0.2) increase in the abnormality rate due to MF exposure. When the morphological abnormality rate of all of the PMF-exposed embryos was compared to that of all of the corresponding control embryos, a statistically significant (P > or = .001) result was obtained, indicating that PMF exposure approximately doubled the abnormality rate. Like-wise, when the abnormality rate of the sinusoid-exposed embryos was compared to the corresponding control embryos, the abnormality rate was increased (approximately tripled). This robust result indicates that weak EMFs can induce morphological abnormalities in developing chick embryos. We have attempted to analyze some of the confounding factors that may have contributed to the lack of response in one of the campaigns. The genetic composition of the breeding stock was altered by the breeder before the start of the nonresponding campaign. We hypothesize that the genetic composition of the breeding stock determines the susceptibility of any given flock to EMF-induced abnormalities and therefore could represent a confounding factor in studies of EMF-induced bioeffects in chick embryos.

Characterization of fatal beta blocker ingestion: a review of the American Association of Poison Control Centers data from 1985 to 1995

OBJECTIVE

To characterize beta blocker-related deaths.

METHODS

This is a retrospective review of beta blocker-related exposure data and fatality case abstracts reported to the American Association of Poison Control Centers Toxic Exposure Surveillance System during the 11 year period, 1985 to 1995. Historical and laboratory data were used to determine those fatalities which resulted primarily from beta blocker intoxication.

RESULTS

Of 52,156 reported beta blocker exposures, 164 were fatal. In 38 cases, beta blockers were implicated as the primary cause of death. Propranolol was responsible for the greatest number of exposures (44%) and implicated as the cause of death in a disproportionately high percentage of fatalities (71%). Patients were generally young women; 63% were female and 92% were less than 50 years old. The dysrhythmias most often noted in fatal cases were bradycardia and asystole. Cardiopulmonary arrest did not develop until patients were in the care of health care personnel in 59% of cases. Though glucagon was initiated more often than any other intervention in fatal intoxications (83%), optimal dosing and maintenance infusions appear to have been underutilized.

CONCLUSIONS

The predominance of fatalities associated with propranolol compared to other beta blockers reflects both its greater frequency of use over the time period studied and its greater toxicity. Since 59% developed. cardiac arrest after reaching health care personnel, further study should focus on identifying medical intervention that can reduce mortality in this group.

State of the national's poison centers: 1995 American Association of Poison Control Centers Survey of US Poison Centers

The American Association of Poison Control Centers (AAPCC) 1995 annual survey is summarized. A decline in the total number of poison centers was noted (from 104 in 1991 to 83 in 1995). The 83 US poison centers handled 2,431, 599 human exposure cases. Certified centers (44) served 63.1% of the US population, handled 72.5% of all poison exposures handled by poison centers nationally, and achieved higher utilization rates within their regions (10.9 vs 7.4 human exposure cases handled/1,000 population). Certified centers had superior staff credentials as measured, by passing the certification examinations for specialists in poison information or board certification for medical and managing directors. Funding for poison centers in 1995 to-total $74.6 million, although this funding level was recognized to be inadequate as only 63.1% of the population was served by certified centers and utilization of poison centers was not optimal. The annual cost of covering the entire US with adequate poison control services (meeting AAPCC certification standards and with utilization at a level of 15 human exposures per thousand population) is estimated at $120 million. Funding difficulties were prevalent. Thirty-five centers indicated that closure had been a real threat at least once in the previous 5 years. Analysis of cost per human exposure case by center volume demonstrated that economies of scale were achieved when a center handled at least 20,000 to 30,000 human exposure calls/year. Increasing human exposure volume beyond 30,000/year did not lead to a reduction in the average cost per human exposure case.

Fatal accidental dibucaine poisoning in children

Dibucaine is a potent amide anesthetic available in over-the-counter preparations. Compared with lidocaine, substantially lower doses of dibucaine may result in seizures, dysrhythmias, and death. We present three fatal cases of accidental dibucaine ingestion in children and discuss the toxicity, treatment, and prevention of such ingestions.

Recurrent poisonings among paediatric poisoning victims

A study of 1943 potentially toxic ingestions occurring in children under 6 years of age was conducted by 3 geographically and demographically diverse poison centres to determine the incidence of exposures to poison. Of the total group, 30.1% indicated that the child had experienced a prior poison exposure (12.0% in children under 1 year of age, and 41.3% of children between the ages of 3 and 5 years). Most repeaters (68.9%) experienced only 1 prior ingestion (range 1 to 15). Two prior ingestions were reported in 17.6% of repeaters; 3 prior ingestions in 4.4%. A profound effect of age on type of substance ingested was observed, with drugs accounting for 11.0% of ingestions in children under the age of 1 year, 23.2% in 1-year-old, and 49.9% in 2- to 5-year-old. A corresponding age-related decline in ingestions of household and personal care products was also noted. Although less marked than the age effect, a statistically significant propensity to re-ingest similar types of poisons was observed. Among repeaters, those with a prior ingestion of a drug subsequently ingested another drug 1.49 times more frequently than expected. A similar trend was observed with products (1.24 times more frequently) and plants (2.00 times more frequently).

Pediatric cyanide intoxication and death from an acetonitrile-containing cosmetic

Two cases of pediatric accidental ingestion of an acetonitrile-containing cosmetic are reported. One of the children, a 16-month-old boy, was found dead in bed the morning after ingesting the product. No therapy had been undertaken, as the product was mistakenly assumed to be an acetone-containing nail polish remover. The second child, a 2-year-old boy, experienced signs of severe cyanide poisoning, but survived with vigorous supportive care. Both children had blood cyanide levels in the potentially lethal range. The observed delayed onset of severe toxic reactions supports the proposed mechanism of acetonitrile conversion to inorganic cyanide via hepatic microsomal enzymes. Physicians and poison centers should be alerted to the existence of this highly toxic product, sold for removal of sculptured nails and likely to be confused with the less toxic acetone-containing nail polish removers. We urge regulatory agencies to reconsider the wisdom of marketing a cosmetic that poses such an extreme health hazard.

Clinical manifestations of toxicity in a series of 784 boric acid ingestions

A retrospective chart review was conducted at two regional poison centers to determine the clinical outcome of boric acid ingestions and to assess the relationship between serum boric acid levels and clinical presentation. A total of 784 cases were studied; all but 2 were acute ingestions. No patients developed severe manifestations of toxicity, and 88.3% were entirely asymptomatic. The most common symptoms were vomiting, abdominal pain, and diarrhea. Lethargy, headache, lightheadedness, and atypical rash were seen less frequently. Boric acid levels were obtained in 51 patients and ranged from 0 to 340 micrograms/mL. Blood levels were 70 micrograms/mL or more in 7 patients; 4 remained asymptomatic, whereas the other 3 had nausea or vomiting. Dialysis was performed in 4 of these 7 patients, only 1 of whom had symptoms (vomiting). On the basis of data from 9 patients, the mean half-life of boric acid was determined to be 13.4 hours (range, 4.0 to 27.8). Hemodialysis in 3 patients significantly shortened the half-life compared with pre- and postdialysis half-lives. Our results suggest that acute boric acid ingestions produce minimal or no toxicity and that aggressive treatment is not necessary in most patients.

Ipecac administration in children younger than 1 year of age

The efficacy of ipecac syrup in the induction of emesis and safety of its administration was studied in 105 poison-exposed infants 6 through 11 months of age (study subjects) and compared prospectively with 302 poison-exposed infants and children 12 through 35 months of age who served as age controls. Of the 105 study subjects 101 (96.2%) vomited. The failure of ipecac to induce emesis in six patients (four of 105 study subjects two of 302 age control subjects) is comparable with ipecac failure rates reported elsewhere. The frequency of side effects caused by ipecac syrup did not differ between study and control subjects. There were no serious medical complications resulting from the administration of ipecac syrup. When not readily available at home, ipecac administration was delayed an additional 21.8 minutes if obtained from a pharmacy and 38.4 minutes if obtained from an emergency department. Because of the time delay and the increased health care cost, home rather than emergency department administration of ipecac should be advised. These data demonstrate that ipecac syrup effectively induces emesis and is safe for home administration to poisoned infants 6 to 11 months old.

Levothyroxine ingestions in children: an analysis of 78 cases

A series of 78 cases of accidental levothyroxine ingestion in children (less than 12 years old) with treatment limited to ipecac-induced emesis and a single oral dose of activated charcoal is presented. No patient received any form of dialysis or hemoperfusion, propylthiouracil, cholestyramine, steroids, or serial doses of oral activated charcoal. Propranolol was used in one case despite the absence of clinical manifestations of toxicity. Only four children developed symptoms, limited to modest fever (38.3 degrees C), supraventricular tachycardia (120-176 beats/min), lethargy, irritability, vomiting, diarrhea, and abdominal pain. Peak T4RIA values in three patients were 32.8, 30.0, and 26.4 micrograms/dl, respectively, and two of these patients remained asymptomatic. Initial therapy for acute levothyroxine ingestions in children can be safely limited to routine gastrointestinal decontamination. Hospitalization or prophylactic treatment with propranolol, propylthiouracil, corticosteroids, cholestyramine, or extracorporeal detoxification are unnecessary in the early asymptomatic phase.

Battery ingestions: product accessibility and clinical course

Results of 125 battery ingestions in 114 separate episodes over an 11-month period are analyzed. The 125 batteries included 119 button batteries and six cylindrical cells. The location of batteries just prior to ingestion (loose or discarded [48.7%], in product [34.4%], in manufacturer's battery packaging [3.4%]) determined the need for consumer education of this potential hazard. The observation that hearing aid batteries were the most common type swallowed (33.9%), and that 14 batteries were ingested by hearing-impaired children after they removed the batteries from their own aids, further directs appropriate prevention efforts. All the larger cylindrical batteries and 89.9% of the button cells passed through the gastrointestinal tract spontaneously. Endoscopic retrieval was unsuccessful in 66.7% of cases attempted. Ipecac syrup, administered to 11 patients, uniformly failed to expel the battery. Transit time was within 48 hours for 68.8% of button cells, and 85.4% of the batteries were passed by 72 hours, with a range of 12 hours to 14 days. Once beyond the esophagus, arrested battery progression failed to correlate with adverse outcome. Symptoms developed in 11 patients but were only severe in the single case of esophageal lodgment. The vast majority of battery ingestions are benign and can be managed without endoscopic or surgical intervention.

The anecdotal antidotes

The author reviews obscure or unusual antidote recommendations, emphasizing antidotes or antidote uses that are not generally acknowledged or that have little experimental or clinical confirmation of their efficacy. Also included are unusual uses of well known antidotes. Among the antidotes considered are naloxone, physostigmine, folate, Prussian blue, n-acetylcysteine, cimetidine, subcutaneous magnesium salts, nicotinamide, and thioctic acid.

Amoxapine overdose. Seizures and fatalities

Thirty-three amoxapine overdoses, including five fatalities, were reported to two regional poison centers over an 18-month study period. The 15.2% mortality rate stands in alarming contrast to the 0.7% death rate for all other cyclic antidepressant overdoses reported to these same two centers during the study. Seizure activity was noted in 36.4% of amoxapine overdoses, compared with 4.3% of other cyclic antidepressant poisonings. Amoxapine appears to be responsible for a disproportionate share of seizures and deaths resulting from cyclic antidepressant overdose.

Button battery ingestions. A review of 56 cases

A retrospective analysis of 56 button (miniature) battery ingestions was conducted. This represents the largest series in the literature studying this problem. Impaction of these foreign bodies, most frequently in the esophagus (five cases), was a uniform predictor of severe morbidity. In the remaining 51 cases, the battery traversed the esophagus without incident; only four of these ingestions produced symptoms, and there was only one case with any severe complications. In 33 asymptomatic patients, the battery passed spontaneously through the gastrointestinal tract. Fourteen patients underwent endoscopic or operative procedures or both despite the absence of symptoms. Unanticipated mucosal erosions were noted in seven of these patients, although no symptoms or sequelae developed. Initial chest roentgenogram and observation for symptoms will detect ingestors at risk of complications. Operative or endoscopic intervention should be withheld in the absence of these clinical indicators. Button batteries can routinely be allowed to pass spontaneously.

Poison center operations: the necessity of follow-up

A retrospective study of 2,526 calls made to a regional poison center demonstrated the value of telephone follow-up of poison exposures. Further treatment recommendations were required in 21.2% of follow-up calls, more than 25% of which were made to physicians. Poison prevention education and data collection were accomplished in more than 95% of cases. Twenty-four telephone follow-up calls corrected major treatment errors, corresponding to a dramatic change in patient management more than twice each week. This study delineates the functions and value of the follow-up call in the treatment and prevention of poisonings and in toxicologic research. Because the effective use of this procedure is limited to comprehensive poison centers with vast resources and full-time staff, this study further supports regionalization to promote maximal utilization of this and other elements of poison control.