Tiêu đề 1. GENERAL PRINCIPLES INVOLVED IN THE MANAGEMENT OF POISONING.pdf ✅

PHARMD GURU Page 1 TOXICOLOGY: The classic definition of toxicology has traditionally been understood as the study of xenobiotics, or simply stated, as the science of poisons — i.e., the interaction of exogenous agents with mammalian physiological compartments. CLINICAL TOXICOLOGY: Traditionally, clinical toxicology was regarded as the specific discipline of the broader field of toxicology concerned with the toxic effects of agents whose intent is to treat, ameliorate, modify, or prevent disease states, or, the effect of drugs which, at one time, were intended to be used as such. These compounds would fall under the classification of therapeutic agents (Part II). A more liberal definition of clinical toxicology involves not only the toxic effects of therapeutic agents but also those chemicals whose intention is not therapeutic. This includes drugs whose exposure has an environmental component (metals), drug use as a result of societal behavior (alcohol and drugs of abuse), chemical by-products of industrial development (gases, hydrocarbons, radiation), or essential components of urban, suburban, or agricultural technologies (pesticides, insecticides, herbicides). These chemicals can be classified as nontherapeutic agents (and constitute Part III of this book), but are in fact associated with a variety of well-known clinical signs and symptoms that warrant discussion as part of a clinical toxicology text. GENERAL PRINCIPLES INVOLVED IN THE MANAGEMENT OF POISONING
PHARMD GURU Page 2 GENERAL PRINCIPLES INVOLVED IN THE MANAGEMENT OF POISONING: There are mainly 6 steps in management of poisoning: 1. Stabilizations 2. Evaluation 3. Decontamination 4. Poison Elimination 5. Antidote Administration 6. Nursing and Psychiatric Care 1. STABILIZATION: The initial survey should always be directed at the assessment and correction of life threatening problems, if present. Attention must be paid to the Airway, Breathing, Circulation, and Depression of the CNS (the ABCD of resuscitation). A - Airway. B - Breathing. C - Circulation. D - Depression of the CNS (CNS depression). ASSESSMENT 1) AIRWAY & 2) BREATHING:  Symptoms of airway obstruction include dyspnoea, air hunger, and hoarseness. Signs comprise stridor, intercostal and substernal retractions, cyanosis, sweating, and tachypnoea. STABILIZATION ASSESSMENT MANAGEMENT
PHARMD GURU Page 3  Increasing metabolic acidosis in the presence of a normal Pa02 suggests a toxin or condition that either decreases oxygen carrying capacity (e.g. carbon monoxide, methaemoglobinaemia), or reduces tissue oxygen (e.g. cyanide, hydrogen sulfide).  The immediate need for assisted ventilation has to be assessed clinically, but the efficiency of ventilation can only be gauged by measuring the blood gases.  Retention of carbon dioxide (PaCO2 > 45 mmHg or 6 Kpa), and hypoxia (Pa02 < 70 mmHg or 9.3 Kpa) inspite of oxygen being given by a face mask are indications for assisted ventilation.  Some drugs stimulate the respiratory centre: amphetamines, atropine, cocaine, and salicylates.  Some drugs are associated with non-cardiogenic pulmonary oedema, characterised by severe hypoxaemia, bilateral infiltrates on chest X-ray, and normal pulmonary capillary wedge pressure.  Some drugs cause or exacerbate asthma. The most important among them include NSAIDs, antibiotics like penicillins and cephalosporins. 3) CIRCULATION:  Several drugs produce changes in pulse rate and blood pressure. Eg: Antihistamines, caffeine produce Tachycardia & Normotension and Amphetamines, cocaine produce Tachycardia & Hypertension.  Some drugs induce cardiac arrhythmias and heart block. Eg: Alpha adrenergic drugs, beta blockers, carbamates produce Sinus Bradycardia or A-V Block and Amphetamines produce Sinus Tachycardia. 4) DEPRESSION OF CENTRAL NERVOUS SYSTEM:  Depression of Central Nervous System is defined as an unarousable lack of awareness with a rating of less than 8 on the Glasgow Coma Scale.  There are numerous causes for coma of which one of the most important is acute poisoning.  A number of substances can induce coma, and it will require a great deal of astuteness and expertise to pinpoint the poison.
PHARMD GURU Page 4 The doctor humanely determines whether the coma is true or fake by: 1. Pinching nipples or genitals, or repeatedly pinching any part of the body. 2. Slapping the face hard, repeatedly.  Cotton pledgets or sterile applicator tips soaked with ammonia solution being inserted into the nostrils.  Perform a quick physical examination with particular attention to the breathing, vital signs, and the gag reflex.  If these are normal, the coma is almost certainly psychogenic.  Another indication is a tightly clenched jaw when attempts are made to open the mouth. However, first rule out seizure disorders.  A useful technique is to lift the patient's hand directly above his face and letting it drop. A psychogenic etiology is almost a certainty if the hand falls gently to his side, rather than obeying the law of gravity and landing on the face.  Pinching the shoulder may also be tried, but must not be repeated more than twice. Some clinicians advocate rubbing the patient's sternum with the knuckles of the clenched fist.