High call volume at poison control centers: identification and implications for communication

CONTEXT

High volume surges in health care are uncommon and unpredictable events. Their impact on health system performance and capacity is difficult to study.

OBJECTIVES

To identify time periods that exhibited very busy conditions at a poison control center and to determine whether cases and communication during high volume call periods are different from cases during low volume periods.

METHODS

Call data from a US poison control center over twelve consecutive months was collected via a call logger and an electronic case database (Toxicall®).Variables evaluated for high call volume conditions were: (1) call duration; (2) number of cases; and (3) number of calls per staff member per 30 minute period. Statistical analyses identified peak periods as busier than 99% of all other 30 minute time periods and low volume periods as slower than 70% of all other 30 minute periods. Case and communication characteristics of high volume and low volume calls were compared using logistic regression.

RESULTS

A total of 65,364 incoming calls occurred over 12 months. One hundred high call volume and 4885 low call volume 30 minute periods were identified. High volume periods were more common between 1500 and 2300 hours and during the winter months. Coded verbal communication data were evaluated for 42 high volume and 296 low volume calls. The mean (standard deviation) call length of these calls during high volume and low volume periods was 3 minutes 27 seconds (1 minute 46 seconds) and 3 minutes 57 seconds (2 minutes 11 seconds), respectively. Regression analyses revealed a trend for fewer overall verbal statements and fewer staff questions during peak periods, but no other significant differences for staff-caller communication behaviors were found.

CONCLUSION

Peak activity for poison center call volume can be identified by statistical modeling. Calls during high volume periods were similar to low volume calls. Communication was more concise yet staff was able to maintain a good rapport with callers during busy call periods. This approach allows evaluation of poison exposure call characteristics and communication during high volume periods.

Esophageal laceration and charcoal mediastinum complicating gastric lavage

A 19-year-old woman underwent multiple attempts at orogastric lavage before success 5 h after ingesting approximately 24 grams of ibuprofen in a suicide attempt. Activated charcoal was administered via the lavage tube. She vomited charcoal shortly after administration and began experiencing difficulty breathing and an increase in the pitch of her voice. A chest X-ray study showed a widened mediastinum, pneumopericardium, and subcutaneous emphysema consistent with esophageal perforation that was confirmed by computed tomography scan. Surgical exploration revealed a tear in the proximal posterior esophagus with charcoal in the posterior mediastinum. She remained intubated for 7 days and was discharged 14 days after admission. This is a report of esophageal perforation with activated charcoal contamination of the mediastinum after gastric lavage. The risks and benefits of this procedure should be carefully considered in each patient prior to its use. Awake patients should be cooperative with the procedure to minimize any risk of trauma to the oropharynx or esophagus.

Unintentional acetaminophen ingestion in children and the potential for hepatotoxicity

OBJECTIVE

Children who unintentionally ingest acetaminophen are often referred to health care facilities for evaluation. Criteria for referral are not well defined and the vast majority of these exposures result in nontoxic serum concentrations. The objective of this study was to determine the incidence of potentially hepatotoxic serum concentrations and to more clearly define referral criteria for these patients.

METHODS

A prospective evaluation of all childhood (age 1-72 months) single ingestions of acetaminophen-containing products was performed by the Utah Poison Control Center. All patients ingesting 140 mg/ kg or greater or an unknown amount were referred for medical evaluation. Patients who ingested greater than 100 mg/kg were advised to administer syrup of ipecac at home if less than 1 hour since ingestion. Activated charcoal was recommended within 2 hours of ingestion if the patient was already at a health care facility. The potential for hepatotoxicity was assessed according to the Rumack-Matthew nomogram.

RESULTS

Inclusion criteria were met by 1015 patients. The mean age was 28 +/- 12 months and mean dose was 213 +/- 148 mg/ kg. Decontamination with ipecac, gastric lavage, or activated charcoal within 2 hours of ingestion occurred in 81% of patients ingesting greater than 140 mg/kg or an unknown amount. Six patients (0.59%, 95% CI 0.12-1.16%) had "possible" or "probable" hepatotoxic serum concentrations and all had ingested greater than 200 mg/kg or an unknown amount. There were 423 patients who ingested between 100 and 200 mg/kg and none had potentially hepatotoxic serum concentrations (upper 95% CL 0.71%).

CONCLUSIONS

Children who ingest between 140-200 mg/kg of acetaminophen and demonstrate ipecac-induced emesis within 60 minutes may be safely managed at home. Patients ingesting greater than 200 mg/kg or an unknown amount should be referred for a serum acetaminophen concentration.

Rhabdomyolysis: a rare adverse effect of diphenhydramine overdose

Drug- and toxin-induced rhabdomyolysis is a nonspecific clinical syndrome resulting from the release of skeletal muscle cell contents into the plasma and urine. Antihistamine drugs are the active ingredients in a number of over-the-counter preparations and are frequently ingested in suicide attempts. We report rhabdomyolysis as a rare adverse effect of diphenhydramine toxicity in a 29-year-old man who ingested an unknown quantity of an over-the-counter sleep preparation in a suicide attempt. The patient had documented toxic concentration of diphenhydramine in his cerebrospinal fluid and no history of seizures, coma, or hypothermia. A high index of suspicion and an evaluation for rhabdomyolysis is warranted in antihistamine toxicity.

Cardiovascular effects of carbamazepine toxicity

STUDY OBJECTIVE

To evaluate the cardiovascular effects of carbamazepine in patients presenting to the emergency department.

DESIGN

A retrospective case series from February 1, 1985, to July 30, 1993.

SETTING

Six urban EDs.

PARTICIPANTS

Seventy-two adult and pediatric patients with serum carbamazepine concentrations greater than 12 micrograms/mL and concurrent 12-lead ECGs.

RESULTS

The mean carbamazepine level was 24 micrograms/mL (range, 12.6 to 55 micrograms/mL). Minor ECG abnormalities were noted but no clinically significant arrhythmias were found. No correlation was found between carbamazepine concentration and heart rate or PR, QRS, or corrected QT intervals. Four adult patients had transient hypotension.

CONCLUSION

Clinically significant cardiovascular toxicity occurs rarely in patients with toxic carbamazepine concentrations. ECG findings do not correlate with serum carbamazepine concentration.

Massive dextromethorphan ingestion and abuse

The case of a 23-year-old man who was acutely intoxicated on dextromethorphan and who was chronically addicted to the drug is described. He consumed the highest daily dose for the longest duration yet reported in the world's English-language medical literature. Toxicity, abuse potential, and therapy of dextromethorphan intoxication are discussed.

Gila monster envenomation

Envenomation from the bite of the Gila monster (Heloderma suspectum) has been reported in the medical literature only nine times since 1956. We present an additional four cases to better define the signs and symptoms of envenomation. Frequent clinical manifestations are pain, hypotension, tachycardia, nausea, and vomiting. Gila monster teeth remaining in the wound are not detectable by soft tissue radiography. In our series, hypotension responded well to i.v. crystalloid fluid administration. We recommend at least 6 hours of observation after the bite to assess the potential for systemic toxicity.

Hydrogen peroxide exposure--325 exposures reported to a regional poison control center

Isolated case reports have documented that hydrogen peroxide exposure can be associated with serious toxicity by various routes of exposure. The purpose of this study was to better delineate the epidemiology, medical outcome, and potential health hazards of hydrogen peroxide exposures to the general public. We performed a retrospective review of all exposures reported to a regional poison center over a 36 month period and found that of 95,052 exposures reported, 325 (.34%) were due to hydrogen peroxide. The pediatric population (< 18 years) accounted for 71% of hydrogen peroxide exposures and ingestion was the most common route of exposure (83%). Nausea and vomiting were the most common symptoms secondary to ingestion. Ocular and dermal exposures to dilute solutions resulted in transient symptoms without permanent sequelae. While most exposures by all routes resulted in a benign outcome (no effect or minor effect), there was a trend toward more severe outcomes in those who ingested a concentration greater than 10% (p = 0.011).

Prospective evaluation of adverse drug interactions in the emergency department

STUDY OBJECTIVE

To determine the incidence and risk factors of clinically relevant adverse drug interactions occurring in emergency department patients.

DESIGN

This report describes the drug interactions identified in an emergency population. Patients' drug regimens were evaluated prospectively at the time of the emergency evaluation.

SETTING

University hospital ED.

TYPE OF PARTICIPANTS

Convenience sample of 341 patients.

INTERVENTIONS

Patients' medications on arrival at the ED (current medications) and medications initiated in the ED were entered into Hansten's computer-based drug interaction program to identify potential drug interactions. All potential drug interactions were brought to the attention of the attending emergency physician, whose subsequent actions were noted. Clinically relevant interactions were determined by a physician panel based on the ED attendings' actions, set criteria, and a review of hospital charts and four-week telephone follow-up of patients with potential drug interactions.

MEASUREMENTS AND MAIN RESULTS

Three hundred forty patients were enrolled. One hundred thirty-five potential drug interactions were identified in 61 patients. Among these 135 potential drug interactions and 61 patients, we identified 20 clinically relevant interactions in 15 patients. The incidence of clinically relevant interactions was significantly higher (chi 2 = 3.95, P = .047) among current medication (9.7%) than medication added in the ED (3.1%). Clinically relevant interaction from both current and ED-initiated medication was associated with taking three or more medications on ED arrival (P = .016 and .045, respectively). Multiple regression showed age of 60 years or older to be the sole predictor of clinically relevant interaction among current medication (P = .05).

CONCLUSION

Clinically relevant adverse drug interaction was significantly less from medication administered or prescribed in the ED than from current medication.

Histamine antagonists in the treatment of acute allergic reactions

STUDY OBJECTIVE

We compared the efficacies of cimetidine (an H2-receptor antagonist) and diphenhydramine (an H1-receptor antagonist) alone and in combination for alleviation of symptoms of acute allergic reactions. STUDY DESIGN AND INTERVENTIONS: In this prospective, randomized, double-blind study, patients and examiners assessed the severity of symptoms and signs of acute allergic reactions using a visual-analog scale before treatment and 30 minutes after treatment with 300 mg IV cimetidine and placebo, 50 mg IV diphenhydramine and placebo, or diphenhydramine plus cimetidine.

SETTING AND PARTICIPANTS

Thirty-nine patients with acute allergic reactions presenting to two emergency departments of teaching hospitals.

RESULTS

Of the 35 patients with pruritus, all 12 receiving diphenhydramine placebo had clinically significant relief compared with six of ten (60%) receiving cimetidine plus placebo (P = .03). Twelve of 13 (92%) receiving diphenhydramine plus cimetidine had relief, which was not a significant difference from the single drugs. Comparison of mean differences in pretreatment and post-treatment symptom scores (relief scores) among groups of patients with pruritus detected significantly more relief in the group receiving diphenhydramine plus placebo (80.3 +/- 7.4) than in those receiving cimetidine plus placebo (48.8 +/- 13.4) (P = .022). Of the 33 patients with urticaria, five of 11 (46%) receiving diphenhydramine plus placebo had clinically significant relief compared with eight of ten (80%) receiving cimetidine plus placebo (P = .18). Eleven of 12 patients (92%) receiving diphenhydramine plus cimetidine had relief, which is a significant difference from those receiving diphenhydramine plus placebo (P = .027). Comparison of mean relief scores in patients with urticaria detected significantly more relief in the group receiving diphenhydramine plus cimetidine (55.3 +/- 6.5) than in the group receiving diphenhydramine plus placebo (30.7 +/- 6.1) (P = .006).

CONCLUSION

For treatment of pruritus from acute allergic reactions, diphenhydramine is more effective than cimetidine, and the combination offers no additional benefit. For treatment of acute urticaria, the combination of cimetidine and diphenhydramine is more effective than diphenhydramine alone.

Use of clinical toxicology resources by emergency physicians and its impact on poison control centers

STUDY OBJECTIVE

The need for clinical toxicology resources by emergency physicians is unclear and may have implications for future training and resource availability. This study was designed to assess current emergency physician use of available resources.

DESIGN

Prospective evaluation by mail using a 49-item questionnaire.

TYPE OF PARTICIPANTS

All 170 emergency physicians in Utah.

INTERVENTIONS

None.

RESULTS

The response rate was 75.3% (128 of 170). Resources "outside their own fund of knowledge" were consulted "occasionally" to "frequently" by 98.3%. They used the following resources "occasionally" to "frequently": poison control center (PCC) (93.7%), toxicology textbook (77.6%), "expert colleague" (34.0%), and "in-house POISINDEX" (23.9%). They often contacted the PCC for toxicity information (93.7%) and management recommendations (87.3%) and for acute, symptomatic overdose cases (88.3%). They "almost never" contacted the PCC for adverse drug reactions (76.6%), pill identification (70.2%), consultation with physician toxicologist (68.1%), asymptomatic exposures (62.9%), chronic toxicity (50.4%), or solely to report the case to the American Association of Poison Control Centers data base (90.2%). Those who had access to in-house POISINDEX often did not consult the PCC (82.6%). Of those who did not have in-house POISINDEX, 42.8% contacted the PCC to access it. Providing access to physician toxicologist consultations was thought to be an important role for the PCC by 86.7%, but only 32% of physicians were using this option.

CONCLUSION

The vast majority of emergency physicians in Utah consult the PCC only for acute, symptomatic overdoses. They view access to physician toxicologist consultation as an important role for the PCC but seldom use it. The availability of in-house POISINDEX decreases the likelihood of PCC consultations from emergency departments. The frequency of emergency physician consultation with the PCC may decrease as POISINDEX becomes available at more hospitals.

Demographic and electrocardiographic factors associated with severe tricyclic antidepressant toxicity

This study was designed to evaluate a historic cohort of pure tricyclic antidepressant overdose patients for factors associated with severe toxicity. Hospitalized tricyclic antidepressant overdose patients were identified by computerized discharge diagnosis (ICD-9 codes). Patients with a serum drug screen positive for tricyclic antidepressants and an emergency department 12-lead electrocardiogram were included in the study. Multiple drug overdoses were excluded. Patients were divided into two groups: minor toxicity (n = 41 and major toxicity (n = 65). Criteria for inclusion in the major toxicity group were the occurrence of seizures, endotracheal intubation, coma, arrhythmias requiring treatment, hypotension, or death. The following were found to be associated with increased likelihood of major toxicity (p less than 0.05): ingestion of amitriptyline (odds ratio (OR) 2.57), age greater than or equal to 30 years (OR 2.56), heart rate greater than or equal to 120 bpm (OR 2.86), serum tricyclic antidepressant level greater than or equal to 800 ng/mL (OR 5.20), terminal 40 ms QRS axis (T40-ms axis) greater than or equal to 135 degrees (OR 2.73), QRS interval greater than or equal to 100 ms (OR 2.74), QRS axis greater than 90 degrees (OR 3.68), and QTc interval greater than 480 ms (OR 3.89). The mean T40-ms axis on the initial ECG was more rightward in the major toxicity group (174 +/- 84 vs 125 +/- 91 degrees, p = 0.006). We conclude that patients with severe tricyclic antidepressant toxicity tended to have a more rightward T40-ms axis than those with minor toxicity and that the presence of the above parameters was associated with an increased likelihood of severe toxicity.

Pediatric coin ingestion. A prospective study on the utility of routine roentgenograms

It has been recommended that all children with a history of coin ingestion immediately undergo roentgenography to locate the coin, regardless of symptoms. We performed a prospective evaluation of these ingestions to determine the risk of asymptomatic esophageal impaction and the need for routine roentgenography. One hundred sixty-two children (mean +/- SD age, 3.6 +/- 2.1 years) were evaluated. All were referred for immediate roentgenography after ingestion and followed up daily by telephone for 5 days. Sixty-six patients (41%) did comply and 96 (59%) did not comply with the roentgenogram recommendation. A coin was visualized in the esophagus of 13 patients (20%); 11 were symptomatic and 2 were asymptomatic at the time of ingestion. Symptomatic patients had a 42% risk of a coin later being located in the esophagus compared with a 5% risk for asymptomatic patients. The asymptomatic patients with lodged coins passed them without difficulty after the administration of oral fluids. Nineteen percent of the patients who did not undergo roentgenography were symptomatic and all became asymptomatic within 24 hours of ingestion. There was no difference in morbidity between the group that underwent roentgenography and the group that did not undergo roentgenography at 5 days after ingestion. Children who are asymptomatic at the time of coin ingestion may not need routine roentgenography if they can tolerate oral fluids and telephone follow-up is available.

Pediatric coin ingestion. A prospective study on the utility of routine roentgenograms

It has been recommended that all children with a history of coin ingestion immediately undergo roentgenography to locate the coin, regardless of symptoms. We performed a prospective evaluation of these ingestions to determine the risk of asymptomatic esophageal impaction and the need for routine roentgenography. One hundred sixty-two children (mean +/- SD age, 3.6 +/- 2.1 years) were evaluated. All were referred for immediate roentgenography after ingestion and followed up daily by telephone for 5 days. Sixty-six patients (41%) did comply and 96 (59%) did not comply with the roentgenogram recommendation. A coin was visualized in the esophagus of 13 patients (20%); 11 were symptomatic and 2 were asymptomatic at the time of ingestion. Symptomatic patients had a 42% risk of a coin later being located in the esophagus compared with a 5% risk for asymptomatic patients. The asymptomatic patients with lodged coins passed them without difficulty after the administration of oral fluids. Nineteen percent of the patients who did not undergo roentgenography were symptomatic and all became asymptomatic within 24 hours of ingestion. There was no difference in morbidity between the group that underwent roentgenography and the group that did not undergo roentgenography at 5 days after ingestion. Children who are asymptomatic at the time of coin ingestion may not need routine roentgenography if they can tolerate oral fluids and telephone follow-up is available.

Nifedipine for the relief of renal colic: a double-blind, placebo-controlled clinical trial

Pain from ureteral stones is believed to be due to spasm and hyper-peristalsis of the involved ureter. Nifedipine has been shown to decrease human ureteral spasm in vitro. Conflicting results have been reported concerning the clinical efficacy of nifedipine in relieving acute renal colic. This prospective, double-blind, crossover clinical trial evaluated the acute pain relief obtained in 30 patients who had ureteral stones. All patients had ureteral stones documented either by plain abdominal radiograph (six), intravenous pyelogram (16), or passage of the stone(s) in the urine (eight). Each patient served as his own control. The mean pain relief scores for placebo versus 10 to 20 mg oral nifedipine were 0.7 +/- 1.8 and 1.2 +/- 2.5, respectively, as measured on a visual analogue scale (P = .404). Seven patients received clinically significant relief associated with nifedipine, and three patients received relief from placebo (P = .300). Twenty patients (66%) did not experience clinically significant relief from either treatment. We conclude that nifedipine does not differ significantly from placebo in providing relief from acute renal colic.

Terminal 40-ms frontal plane QRS axis as a marker for tricyclic antidepressant overdose

Tricyclic antidepressant (TCA) poisoning has been reported to cause a right-axis deviation of 130 degrees to 270 degrees in the terminal 40-ms frontal plane QRS axis (T40-ms axis) of the ECG. This retrospective cohort study was designed to determine if the T40-ms axis could discriminate TCA-toxic patients from other overdose patients and whether a correlation exists between TCA plasma concentration and T40-ms axis rotation. Only symptomatic overdose patients with plasma and urine drug screens and an ECG obtained within two hours of each other were included in the study. Patients were divided into two groups: TCA overdose patients (TCA OD, n = 48) and nonTCA overdose patients (nonTCA OD, n = 30). The mean T40-ms axis was significantly more rightward in the TCA OD group compared with the nonTCA OD group (179 +/- 74 vs 86 +/- 87, P less than .001). A TCA OD patient was 8.6 times more likely to have a T40-ms axis of more than 120 degrees than was a nonTCA OD patient (odds ratio, 8.6; 95% confidence interval, 2.7 to 29.1). Eight of the TCA poisoned patients (17%) did not demonstrate a T40-ms axis between 120 degrees and 270 degrees. Receiver operating characteristics demonstrated that the T40-ms axis was a better indicator of TCA toxicity than the QRS interval (P less than .05). A T40-ms axis of 120 degrees or more was 83% sensitive and 63% specific for TCA overdose. A correlation between plasma TCA concentration and T40-ms axis deviation was not found (r = .04).(ABSTRACT TRUNCATED AT 250 WORDS)

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.

Fetal toxicity associated with maternal carbon monoxide poisoning

We report six cases of acute carbon monoxide poisoning during pregnancy. All of the women survived with good outcomes, but three cases were associated with fetal mortality. Two fetuses were delivered stillborn within 36 hours of exposure. One fetus remained alive in utero for 20 weeks and was delivered nonviable at 33 weeks gestation with multiple morphologic anomalies. Three pregnancies were carried to term and resulted in normal neonates. Maternal blood carboxyhemoglobin levels did not correlate with the concurrent severity of symptoms in the woman. Maternal symptoms at the site of exposure seemed to predict the risk of associated morbidity to the fetus. A single maternal carboxyhemoglobin level cannot be used to estimate fetal carboxyhemoglobin if the exposure pattern is not known.

Acute hydrofluoric acid exposure

Significant local and systemic toxicity may occur from hydrofluoric acid by all routes of exposure. Prompt decontamination by removal from the source and copious irrigation of eyes and skin are essential to reduce morbidity and mortality. Ingestion of small amounts of HF can lead to rapid systemic poisoning and death. Calcium gluconate therapy has become the preferred method of detoxifying the fluoride ion, although its efficacy is based mainly on anecdotal reports and poorly controlled clinical studies. Therefore, more basic research is needed to elucidate the pathophysiology of local toxicity and the best therapeutic modalities to limit injury. All significant exposures should be evaluated by health care personnel familiar with the potential toxicity of this compound.

Clonidine transdermal patch poisoning

A case of infant clonidine poisoning from a transdermal patch that had been worn for five days by an adult and then discarded is described. The infant became hypotensive with a systolic blood pressure of 38 mm Hg, and a dopamine infusion was required for six hours to maintain adequate blood pressure. The infant was discharged 24 hours after admission. Clonidine toxicity, transdermal delivery system pharmacokinetics, and poison prevention are discussed.

Metabolic abnormalities associated with phosphoric acid ingestion

A 64-year-old man ingested a phosphoric acid solution in a suicide attempt. He subsequently developed hyperphosphatemia, hypocalcemia, and systemic metabolic acidosis. Local caustic effects of the acid were mild. The patient recovered and was lost to follow-up.

Hypokalemia, hyperglycemia, and acidosis after intentional theophylline overdose

Three cases of intentional theophylline overdose in adult patients are described. Among these, hypokalemia, hyperglycemia, and acidosis were found, and markedly elevated initial serum theophylline concentrations (106, 76.2, and 41.4 micrograms/ml) were measured. All patients recovered completely with conservative management. The observed biochemical abnormalities rapidly resolved during maintenance fluid therapy and modest potassium supplementation. In addition, seizures, ventricular arrhythmias, and other serious toxic effects were notably absent.