Colyte

NEW YORK -- Management of a patient who has ingested poison or an overdose of pills should be determined as much by when the ingestion occurred as by what the person swallowed, Dr. Robert Hoffman said at a program on primary care emergencies, sponsored by Symposia Medicus.

The basic treatment options--syrup of ipecac, gastric lavage, activated charcoal, cathartics, and whole bowel lavage--each have their place. The choice of when to use which approach is highly situational, but "more often than not, you do not have to be aggressive," said Dr. Hoffman, director of the New York City Poison Control Center.

He offered these guidelines for using each of the five treatment options:

* Syrup of Ipecac. "If I put ipecac in your soda, 88% of you will vomit within the next 10-20 minutes, Dr. Hoffman told attendees. "Very few things in medicine work 88% of the time."

The problem is, from the point of view of poison control, vomiting is not equal to efficacy Induction of vomiting with ipecac is useless if the patient presents several hours after ingestion; 2 or 3 hours is plenty of time for poisons or drugs to be digested and assimilated. Ipecac is useful only if given within an hour of ingestion.

Dr. Hoffman's general rules for ipecac are: The ingested substance must be a non caustic toxin; the ingestion has to be recent; and the patient has to be conscious and functional. Never induce vomiting in someone who is unconscious, delirious, seizing, or in a drug-related significantly altered state.

Always ask if the person has already vomited; there is nothing gained by inducing a repeat. "Induction of vomiting should never be used as 'punishment,'" he stressed.

The ideal scenario for using syrup of ipecac is the case in which a parent walks in, sees his or her 3-year-old eating large quantities of aspirin, and calls your office in a panic.

Adults can usually be treated with 30 mL of ipecac with 240-480 mL of water. For children under 12, use 15 mL with 240 mL of water. Ipecac should not be used in babies under 6 months, but for those aged 6-12 months, you can safely use it at a dose of 5-10 mL with 15 mL water per kilogram of body weight.

* Gastric Lavage. "It is pretty brutal," Dr. Hoffman admitted. "The condition has to be absolutely life threatening for me to lavage someone."

Many of the same guidelines for ipecac apply to lavage: It is helpful only within 12 hours of ingestion and should be used only when induction of vomiting with ipecac is contraindicated--situations such as tricyclic antidepressant overdose, in which a rapid decline in mental status or vital signs is expected.

Lavage is the preferred approach only in those patients who have lost their gag reflex and who are intubated for airway protection, he said.

* Activated Charcoal. "For the average overdose, this is a very reasonable approach," Dr. Hoffman stated. "A teaspoon of activated charcoal has the surface area of a tennis court." It is very absorptive, prevents toxin absorption in the gut, and binds bile, thus blocking enterohepatic enzymatic digestion of drugs.

Charcoal is excellent when the patient presents several hours after ingestion, and the toxin is already in the absorptive phase of digestion. In some situations, charcoal in the intestines can actually draw toxins or drug metabolites from the blood. This is the case with theophylline.

The problem with charcoal is that to be effective it must be taken in a roughly 10:1 ratio with the substance ingested. If the patient has swallowed dozens of pills, it can be very difficult to load in adequate quantities of charcoal. And large numbers of pills may clump together, forming concretions that are not easily neutralized with charcoal.

In these cases, gastric emptying maybe warranted prior to giving charcoal, so long as the pills are still in the stomach, Dr. Hoffman said.

Charcoal is generally safe for a wide range of patients and ages, though it should not be given to anybody with decreased GI motility, he noted.

If a patient is conscious and objects to drinking large quantities of charcoal, you can sometimes improve compliance by giving the patient a quick look at the lavage hose and explaining that this is the alternative, Dr. Hoflinan said.

Repeated dosing with charcoal, typically every 6 hours, is warranted in overdoses of phenobarbital, theophylline, digoxin, digitoxin, phenytoin, and carbamazepine. It also makes good sense if the patient has ingested sustained-release formulations of any type of drug. But be aware that repeated dosing of large quantities can result in formation of solid charcoal aggregates--essentially briquettes-- in the patient's gut, which must be removed surgically.

*Cathartics. Theoretically use of a cathartic agent such as magnesium sulfate, magnesium citrate, or sorbitol, along with activated charcoal makes a lot of sense. "If [the toxin] is in the bedpan instead of your intestines, it can't poison you," he said. But there is little evidence that use of cathartics really reduces the absorption of poisons. The only strong indication is in salicylate overdose, since salicylate can be released by the activated charcoal late in the digestive process.

Of the available agents, Dr. Hoffman prefers sorbitol because of its quick onset of action. Patients usually begin defecating within an hour; magnesium products can take 4-16 hours to work. Most adults can be given a 70% sorbitol solution at a dose of 1 g per kilogram of body weight; for children, use a 35% solution.

Be aware that some activated charcoal products already contain a cathartic agent; if you use one of these, do not give an additional cathartic.

* Whole Bowel Irrigation. The process of instilling and then flushing large volumes of irrigation solutions such as Colyte or Golytely is "unbelievably messy and labor-intensive," he said.

Although this- is no substitute for activated charcoal, it is very useful when a patient has swallowed substances such as iron, lead, lithium, or zinc, which will not bind easily to charcoal.

Irrigation is also good in cases involving large quantities of sustained-release tablets or those involving drug-smuggling "body-packers" who have swallowed large numbers of condoms filled with heroin or cocaine.

Aggressive irrigation requires that adult patients receive 2 L/hr, either by actively drinking or via nasogastric tube, for 4-6 hours. Children can be treated with 0.5 L/hr, Dr. Hoffman said.

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