Article, Toxicology

A retrospective review of the prehospital use of activated charcoal

a b s t r a c t

Objective: We studied the complications and timing implications of prehospital activated charcoal (PAC). Appropriateness of PAC administration was also evaluated.

Methods: We retrospectively reviewed prehospital records over 32 months for overdose cases, where PAC was administered. Cases were assessed for amount and type of ingestant, clinical findings, timing of PAC, timing of transport and arrival into the emergency department (ED), and complications. Encounter duration in cases of PAC was compared with that, for all cases during the study period, where an overdose patient who did not receive activated charcoal was transported.

Results: Two thousand eight hundred forty-five total cases were identified. In 441 cases, PAC was given; and complications could be assessed. Two hundred eighty-one of these had complete information regarding timing of ingestion, activated charcoal administration, and transport. The average time between overdose and PAC was 49.8 minutes (range, 7-199 minutes; median, 41.0 minutes; SD, 30.4 minutes). Complications included emesis (7%), declining mental status (4%), declining blood pressure (0.4%), and declining oxygen saturation (0.4%). Four hundred seventeen cases of PAC had documentation of timing of emergency medical service (EMS) arrival on scene and arrival at the ED. Average EMS encounter time was 29 minutes (range, 10-53 minutes; median, 27.9 minutes). Two thousand forty-four poisoning patients were transported who did not receive PAC. The average EMS encounter time for this group was 28.1 minutes (range, 4-82 minutes; median, 27.3 minutes), not significantly different (P =.114).

Conclusions: Prehospital activated charcoal did not appear to markedly delay transport or arrival of overdose patients into the ED and was generally safe.

Introduction

Activated charcoal (AC) is the preferred method of decontamination when indicated for a variety of intoxicants. Activated charcoal contains a complex pore structure and a large surface area allowing it to bind intoxicants in the gastrointestinal tract, thereby preventing systemic absorption. It is generally well tolerated and has few side effects [1]. Activated charcoal can be given for a wide variety of toxic ingestions but is not generally recommended for poisonings with alcohol, hydro- carbons, corrosives, or heavy metals [1,2]. Timing of charcoal adminis- tration is crucial to its efficacy in oral overdose, as several volunteer studies have shown that AC can significantly reduce drug absorption when given within 1 hour of drug ingestion, but becomes much less effective if given more than 1 hour after ingestion [3-5].

For the period examined in this study, our city’s protocol for the ad- ministration of AC included ingestion of a substance Potentially bound

* Corresponding author. 200 W Arbor Dr, San Diego, CA 92103.

E-mail address: [email protected] (R.F. Clark).

by AC with a cooperative patient whose gag reflex is intact. Paramedics in our prehospital system in many cases contact our local poison control center for assistance in management of overdose patients before arrival in an emergency department (ED). In some cases, this prevents transport, when a nontoxic exposure has occurred. City prehospital protocol allows administration of up to 50 g of AC by standing order or in consultation with our poison control center or a base hospital. Consultation with poison control or a base hospital is not mandatory for AC to be administered. The protocol in use during the study period specifically did not distinguish between substances ingested when recommending AC but does exclude its use in cases of isolated alcohol, heavy metals (including iron), caustic agents, and hydrocarbons.

Although the relative safety of AC in the hospital setting has been established, few studies have examined the safety of AC in the prehospital setting [6,7]. In addition, there may be concern that the administration of AC in the field may delay transport of patients and ultimately delay their arrival into the ED. We attempted to examine ambulance transport times, appropriateness of administration, and complications in prehospital AC administration.

http://dx.doi.org/10.1016/j.ajem.2014.10.019

Methods

J. Villarreal et al. / American Journal of Emergency Medicine 33 (2015) 56-59 57

Table 1

We retrospectively reviewed the emergency medical service (EMS)

Intoxicants ingested by subjects receiving prehospital AC. “Pure ingestions” were defined as only 1 substance by history. “Total ingestions” also included those cases where multiple

intoxicants were ingested

records for a large urban community to identify cases with a dispatch

reason listed as “poisoning/drug ingestion” during the period starting

Class Pure ingestions Total ingestions

on May 1, 2010, and ending on December 31, 2012. Cases of patients Benzodiazepine who received prehospital AC and were transported by ambulance to a Antidepressants	47 (11%) 32 (7%)	127 (29%) 97 (22%)
local hospital were then selected out from the total group identified. ^SSRI	13 (3%)	46 (10%)
Identified cases were abstracted by one of the authors trained in data TCA	4 (1%)	10 (2%)
SNRI	0 (0%)	4 (1%)
abstraction who entered data into a standard Excel (Redmond, WA) _Other	15 (3%)	37 (8%)
spreadsheet of variables agreed upon by all authors. A sample of located NSAID cases was independently reviewed by 2 other authors to insure W/ codeine	37 (8%) 1 (b1%)	91 (20%) 2 (b1%)
Interrater agreement. Variables collected were decided before review ^W/ ^{antihistamine}	1 (b1%)	4 (1%)
Opioid	26 (6%)	67 (15%)

in the records that occurred during transport, whether they resulted

and for each case included amount and type of intoxicant ingested,

W/ APAP

16 (4%)

45 (10%)

timing of intoxicant ingestion, clinical findings on arrival of medics,

Antihistamine

17 (4%)

58 (13%)

time of administration of AC, timing of transport and arrival into the ED, and complications during transport. We believed that it is important

to list common and potentially clinically significant complications listed

Hypnosedative Acetaminophen

W/ antihistamine

W/ codeine

21 (5%)

22 (5%)

6 (1%)

0 (0%)

54 (12%)

57 (13%)

12 (3%)

1 (0.2%)


Antiepileptic	10 (2%)	33 (7%)

(b 90 systolic with a drop of >=30 mm Hg from baseline), decline in ox- ygen saturation (b 90% with a drop in oxygen saturation as measured by pulse oximetry of >= 5%), or declining mental status (compared with baseline, subjectively described as becoming “unarousable” or with Glasgow Coma Scale b 11 by paramedics), after patients received AC. In addition, cases were assessed for emesis after administration of AC.

? blocker 2 (b1%) 7 (2%)

Ca channel blocker 2 (b1%) 4 (1%)

from AC administration. “Complications” were predetermined by the	Antihypertensive	11 (2%)	33 (7%)
study team before case review and defined as decline in blood pressure	ACE inhibitor	3 (1%)	9 (2%)

Thiazide 0 (0%) 3 (1%)

ARB 1 (b1%) 2 (b1%)

Other 3 (1%) 8 (2%)

Muscle relaxant 7 (2%) 20 (4%)

Antibiotic 3 (1%) 10 (2%)

Anticoagulant 4 (1%) 9 (2%)

If none of the defined complications was mentioned in the prehospital	Excedrin	4 (1%)	8 (2%)
record, it was assumed to have not occurred.	Opioid	3 (1%)	7 (2%)

From the timing of data collected, the duration in each case of the overall EMS encounter, transport time, and elapsed time from intoxicant ingestion to AC administration was recorded. Overall encounter duration was defined as the time elapsed from EMS arrival on scene to EMS arrival at the ED. Overall encounter duration in cases of AC administration was then compared with overall encounter duration for cases who did not receive AC but were transported by am- bulance and for whom the dispatch reason was listed as “poisoning/ drug ingestion.” The mean overall encounter durations for these groups were compared using the 1-tailed Student t test with differences being considered significant at P b .05. Tolerance of AC was also recorded, and tolerance was assessed in the study by whether patients were able to drink any amount of AC without emesis. This study was approved by the human research protection program of our institution.

Results

A total of 2485 cases were identified during the study period who were transported with a dispatch reason of “poisoning/drug ingestion,” with complete records for abstraction. Four hundred forty-one cases were identified, where prehospital AC was given. The toxic ingestion was known in 380 of these cases. Patients in the study ingested a wide variety of intoxicants (Table 1). A significant portion of overdoses (33%) were combination ingestions with 2 or more substances being ingested. Only 1 case involved the pure ingestion of an intoxicant that would have fallen out of the city’s standing protocol (lithium). In 2 cases, AC was given despite documentation that there was no knowl- edge by EMS personnel as to what type of pill the patient had ingested. Of the 441 total cases, 29 patients (7%) were unable to tolerate AC due to emesis or gagging.

Complications occurred in 46 cases (10.4%, Table 2). Recorded com- plications included emesis in 29 cases (7%), declining mental status in 20 cases (5%), 2 patients who developed declining blood pressure (0.5%), and 2 patients whose oxygen saturation declined after AC (0.5%). We were unable to obtain follow-up information on the cases of complications.

Cold medication 3 (1%) 7 (2%)

Lithium 1 (b1%) 6 (1%)

Amphetamine 1 (b1%) 4 (1%)

Statin 1 (b1%) 3 (1%)

Melatonin 1 (b1%) 3 (1%)

Multivitamin 1 (b1%) 3 (1%)

Platelet inhibitor 1 (b1%) 2 (b1%)

Levothyroxine 0 (0%) 2 (b1%)

Metformin 0 (0%) 1 (b1%)

Iron 0 (0%) 1 (b1%)

Anticholinergic 0 (0%) 1 (b1%)

Dopamine agonist 0 (0%) 1 (b1%)

Cough syrup 0 (0%) 1 (b1%)

Abbreviations: SSRI, serotonin selective reuptake inhibitor antidepressants; TCA, triCyclic antidepressants; SNRI, serotonin nonselective reuptake inhibitor antidepressants; NSAID, nonsteroidal antiinflammatory drug; APAP, acetaminophen; ACE, angiotensin-converting enzyme inhibitor; Ca, calcium; ARB, angiotensin receptor blocker.

Of the 441 total cases, 281 cases had complete documentation regarding timing of intoxicant ingestion relative to AC administration. The average elapsed time between intoxicant ingestion and AC adminis- tration was 49.8 minutes (range, 7-199 minutes; median, 41.0 minutes; SD, 30.4 minutes). Activated charcoal was given more than1 hour after intoxicant ingestion in 63 cases (22%), and AC was given more than 2 hours after intoxicant ingestion in 9 cases (3%).

Of the 441 total cases, 417 cases had complete documentation of the timing of EMS arrival on scene and arrival at the ED. For these 417 cases, the average total EMS encounter time was 29 minutes (range, 10-53 minutes; median, 27.9 minutes), and the average total transit time was 15 minutes (range, 2-38 minutes; median, 13.8 minutes). Dur-

Table 2

Complications reported in patients administered prehospital AC

Complication % (n)

Emesis 6.6% (29)

Decline in mental status 4.5% (20)

Hypotension 0.5% (2)

Hypoxia 0.5% (2)

58 J. Villarreal et al. / American Journal of Emergency Medicine 33 (2015) 56-59

ing the same study period from May 1, 2010, to December 31, 2012, there were 2044 patients transported by ambulance who did not receive AC and who had a reason for dispatch of “poisoning/drug ingestion.” The av- erage total EMS encounter duration for this group was 28.1 minutes (range, 4-82 minutes; median, 27.3 minutes), which was not significantly different than in the main study group (P =.114).

Discussion

Our study found that what we defined as complications after admin- istration of prehospital AC were uncommon and often could have been related to the ingestion itself. We also found that, in our EMS system, the administration of prehospital AC in situations where it may be contrain- dicated is also rare; but implementation more than 1 hour after toxic in- gestion, when efficacy of AC is thought to decrease significantly, was more common. Emesis composed most of the complications seen in our study. Furthermore, the elapsed time from paramedic arrival to ar- rival in the ED in our cases, where prehospital AC was administered, seems to be similar to the average total encounter duration in poisoning and drug ingestions, where prehospital AC was not administered.

Activated charcoal is the most commonly used method of gastroin- testinal decontamination for the poisoned patient [8], with several stud- ies suggesting that AC has less adverse effects and better clinical outcomes compared with other forms of gastrointestinal decontamina- tion such as syrup of ipecac and gastric lavage [9-11]. Despite this, pre- vious studies examining the use of AC in oral overdose cases have not been able to demonstrate an improvement in parameters such as length of hospital stay, complication rates associated with overdose, or mortal- ity [12,13]. Activated charcoal is nonetheless commonly used in oral overdose, as several volunteer studies have shown significant reduc- tions in amount of toxin absorption, when AC is given within 1 hour [3-5]. There is no known optimal dose of AC, but the United States Pharmacopeia recommends that adults receive 25 to 100 g of AC, with children aged 1 to 12 years receiving 25 to 50 g or 0.5 to 1.0 g/kg. Many toxicologists recommend 1 g/kg body weight as a starting dose. According to current recommendations, AC is contraindicated in patients with an unprotected airway or patients with a high aspiration risk [2]. Activated charcoal is also contraindicated in patients with gastrointestinal pathology or recent gastrointestinal surgery due to the risk of hemorrhage or gastrointestinal perforation [2]. Previous studies of in-hospital use of AC show that complications are rare, with emesis being the most commonly reported complication. Rates of emesis documented by in-hospital studies range from 7% to 23% [12,14,15]. Although aspiration is occasionally seen with AC use, several studies have shown that aspiration is not more common in overdose patients who receive AC compared with those who do not [8,16].

There are few studies that have examined complications seen with

prehospital AC [6,17]. One small report on prehospital AC found a rate of emesis after prehospital AC use of 7% and found no other significant complications [17]. Our finding of emesis in 7% of prehospital AC treat- ments is consistent with the rates found in previous studies of both in- hospital and prehospital AC use. Other complications observed in our study, such as hypotension, hypoxia, and declining mental status were possibly due to the toxic ingestion rather than the AC itself. Overall, our data suggest the general safety of AC previously shown in the in- hospital setting seems to be similar to our prehospital setting, confirming previous studies from other systems [6].

Guidelines from the American Association of Poison control centers for prehospital management of various toxic overdoses including acet- aminophen, atypical antipsychotics, tricyclic antidepressants, selective serotonin reuptake inhibitors, calcium channel blockers, salicylates, Valproic acid, and ? blockers state that prehospital AC may be given for overdose but emphasize that it should not delay ambulance trans- portation [18-25]. A previous small study of prehospital AC use found that its administration did not significantly delay Patient transport times [17]. Another larger study suggested that prehospital is feasible

even in Severe poisonings [6]. Total encounter duration times in our study were comparable with those seen in poisoning and drug ingestion cases where no AC was given, suggesting that use of AC by EMS person- nel in our city is not markedly delaying patient transport.

The effect of AC is time dependent, and past studies have shown that treating patients in the prehospital setting would allow the treatment of more patients within the recommended 1-hour window [26]. Even if overdose patients arrive at the ED within 1 hour of toxic ingestion, long delays from arrival to AC therapy are common as shown by a recent study of pediatric toxic ingestion cases in which the average elapsed time between EMS arrival at the hospital and AC ingestion was 65 minutes [27]. Our study shows that a large number of patients are able to be treated within the first hour after intoxicant ingestion, although many overdose patients did receive AC more than 1 hour after intoxicant ingestion at a time when the theoretical benefits of AC may be decreased. Finally, our study suggests that our EMS personnel successfully avoid giving AC to patients who have ingested an intoxicant that would not be amenable to effects of AC.

A major limitation of our study is its retrospective design, which could result in missed cases and incomplete data capture. We were lim- ited to using the documentation as recorded by paramedics that could have been incomplete or inaccurate. The actual timing and amounts and substances ingested may not have been completely known in all cases. In addition, we were not able to evaluate the rate of “complica- tions” in patients who did not receive AC, thus making it impossible to compare the complication rate in the 2 groups. Furthermore, our study did not track patient outcomes after arrival in the ED. Doing so would allow us to ascertain a potential clinical benefit of prehospital AC decontamination. Finally, although the group of EMS cases with a dispatch reason of “poisoning/drug ingestion” likely provides a fairly accurate metric for evaluation of paramedic encounter duration in prehospital AC cases, cases still may not have been comparable due to differences in demographics or other characteristics.

Conclusions

In our study group, the prehospital treatment of patients by our city’s paramedics with AC did not appear to markedly delay transport or arrival of overdose patients into the ED; and paramedics largely avoided administration in cases, where AC might be contraindicated. Whether accurate patient selection is related to EMS interaction with a poison control center could not be assessed. The rate of “complica- tions” reported in the records of our study group who received AC appeared to be uncommon. Further studies are required to evaluate the effect of prehospital AC decontamination on patient outcomes.

References

AJEM