Thursday, March 21, 2013

Poisoning - Its Clinical Manifestation and Management

Acute poisoning accounts for about 4-7% of admissions into major general hospitals in the world. Poisoning may be suicidal, accidental or homicidal. The high incidence of poisoning is attributed to the widespread use and free availability of insecticides, pesticides and other harmful chemicals for use in agriculture and industry. Depending upon the cost and local availability, varied substances are used.

In the order of frequency, the toxic agents include organophosphorus compounds, barbiturates, vegetable poisons, phenothiazines, corrosive acids, and several others. The precipitating factors which drive persons to commit suicide are depressive illness, financial problems, domestic conflicts, and frustration in studies, jobs or incurable illness. Among epileptics and alcoholics, the incidence of suicidal poisoning is high. Accidental poisoning is common in children. Persons engaged in the use of toxic chemicals in agriculture and in industry are liable to suffer if proper safety precautions are not adhered to.

Clinical presentation of acute poisoning: Though poisoning by many chemicals lead to characteristic clinical features, in the majority of cases, symptoms are nonspecific and may be mistaken for other acute illnesses. The common presentations are coma, acute psychosis, convulsions, gastroenteritis, circulatory collapse, or pulmonary edema. Corrosive poisons produce noticeable lesions at the points of maximum contact such as the mouth, esophagus and stomach. other poisons affect specific organs maximally, e.g, Liver damage in paracetamol poisoning, renal damage in copper sulphate poisoning, and Cardiac dysfunction in Cerebral odullum poisoning. Poisons consumed on an empty stomach are absorbed more rapidly than if taken on full stomach. Also, if taken along with alcohol, many poisons are quickly absorbed and their damaging effects are cumulative.

Diagnosis: Diagnosis is rendered easy if proper history or evidence of the material is obtained, but in many cases such help is not available. A high index of suspicion on the part of the physician is absolutely necessary for arriving at an early diagnosis in such cases. Abrupt occurrence of acute illness in a person who is in good health should suggest acute poisoning as a possibility. Smell of alcohol or kerosene, severe respiratory depression, circulatory collapse, convulsions, constricted pupil, Cardiac arrhythmia's, dystonic postures, and muscle fasciculations add support to this diagnosis. The outcome depends upon factors like:

1. The amount of poison and its mode of administration
2. Presence of food in the stomach at the time of ingestion.
3. delay in starting treatment.
4. Age,
5. General health and concurrent illness, and
6. Availability of specific antidotes.

Patients who are comatose owing to acute poisoning face the twin dangers of the toxic effects of the chemical and the grave consequences of an obstructed airway.

general management of acute poisoning: Acute poisoning is a medical emergency and is best treated in a well-equipped hospital with teams specially trained to handle such cases. Since in many cases the nature of the poison will not be evident at first, the aim of treatment is to keep the patient alive with support of vital functions and eliminate as much of the poison as possible from the body. Specific antidotes are given as soon as the nature of the poison is known.

Supportive management: Most important is to clear the airway and ensure adequate ventilation. If there is respiratory depression, stimulants like nikethemide (500 mg) should be given along with oxygen inhalation. Intermittent positive pressure respiration has to be instituted after tracheostomy or endotracheal intubation, if conservative measures fail. The patient should be turned from side to side at four hourly intervals to prevent aspiration and hypostatic Pneumonia. Frequent bronchial suction helps in preventing atelectasis and aspiration Pneumonia. Shock is managed on the usual lines. Maintenance of fluid and electrolyte balance is of utmost importance in all cases. An intake-output chart should be maintained and a urine output of 1500 ml should be ensured. Replacement of electrolytes and correction of acidosis should be done with proper laboratory monitoring. Maintenance of nutrition is equally important. Diet containing 2000 calories should be given through a nasogastric tube or parenterally. Repeated examination of blood and urine help in monitoring the level of poison in blood and the amount eliminated.

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