Pyrimidinemia familial
Overview
A metabolic error where a deficiency of an enzyme called dihydropyrimidine dehydrogenase prevents the normal metabolism of certain proteins. High levels of certain proteins are excreted in the urine. The enzyme is also needed the breakdown a chemotherapy drug called 5-flurouracil and its absence can result in a severe toxicity reaction.
Symptoms
* Seizures * Hypertonia * Increased reflex response * Small head * Deficiency of dihydropyrimidine dehydrogenase * Brain dysmyelination * Low blood platelet level * Reduced number of neutrophils in blood * Fluoouracil toxicity * Abnormal brain (cerebral) function * High uracil level in urine * High thymine level in urine * High 5-hydroxymethyluracil level in urine * Convulsions
Causes
Of the approximately 45,000 snakebites that occur in the United States each year, 7,000 to 8,000 are from poisonous snakes, resulting in 5 to 6 deaths. Such bites are most common during summer afternoons in grassy or rocky habitats. Pit vipers are nocturnal but active snakes that are responsible for 99% of venomous snake bites in the United States. Coral snakes are also nocturnal, but their placidity makes coral snake bites less common than pit viper bites. Coral snakes tend to bite with a chewing motion, and may leave multiple fang marks, small lacerations, and extensive tissue destruction.
Treatment
Prompt, appropriate first aid can reduce venom absorption and prevent severe symptoms. ❑ If possible, identify the snake, but don’t waste time trying to find it. ❑ Place the victim in the supine position to slow venom metabolism and absorption. ❑ Don’t give the victim any food, beverage, or medication orally. ❑ Authorities disagree about what constitutes appropriate prehospital care. Some recommend against placing a constrictive tourniquet (band) on the affected limb unless the victim is far from a medical facility. ❑ Whether you apply a tourniquet or not, immediately immobilize the victim’s affected limb below heart level, and instruct the victim to remain as quiet as possible. ❑ If a tourniquet is applied, the victim or the person applying the tourniquet should check the victim’s distal pulses regularly and loosen the tourniquet slightly as needed to maintain circulation. Remember that the goal of applying a tourniquet is to obstruct lymphatic drainage, not blood flow. ❑ When indicated, apply the tourniquet so that it’s slightly constrictive, obstructing only lymphatic and superficial venous blood flow. Apply the band about 4(10 cm) above the fang marks or just above the first joint proximal to the bite. The tourniquet should be loose enough to allow a finger between the band and the skin. After the tourniquet is in place, don’t remove it until a physician has examined the victim. Alert Don’t apply a tourniquet if more than 30 minutes have elapsed since the bite. Keep in mind also that total tourniquet time shouldn’t exceed 2 hours and that the use of a tourniquet shouldn’t delay antivenin administration. Loss of a limb is possible if a tourniquet is too tight or if tourniquet time is too long. ❑ If the patient is more than a few hours away from a hospital, wash the skin over the fang marks. Within 5 to 15 minutes of a pit viper bite, make an incision through the fang marks about ½"(1.3 cm) long and ⅛"(3.2 mm) deep. Be especially careful if the bite is on the hand, where blood vessels and tendons are close to the skin surface. Using a bulb syringe — or, if no other means is available, mouth suction — apply suction for up to 1 hour in the absence of antivenin administration. Alert Remember, an incision and suction are effective only in pit viper bites and only within 1 hour of the bite. Suction is also indicated if transport time to an emergency facility would exceed 30 minutes. Mouth suction is contraindicated if the rescuer has oral ulcers, if the victim is close to a medical facility, or if antivenin can be given promptly. Alert Never give the victim alcoholic drinks or stimulants because they speed venom absorption. Never apply ice to a snakebite because it will increase tissue damage. ❑ Record the signs and symptoms of progressive envenomation and when they develop. Most snakebite victims are hospitalized for only 24 to 48 hours. Treatment usually consists of antivenin administration, but minor snakebites may not require antivenin. Other treatments include tetanus toxoid or tetanus immune globulin; various broad-spectrum antibiotics; and, depending on respiratory status, severity of pain, and the type of snakebite, acetaminophen, codeine, morphine, or meperidine. (Opioids are contraindicated for the treatment of coral snakebites.) Necrotic snakebites usually need surgical debridement after 3 or 4 days. Intense, rapidly progressive edema requires fasciotomy within 2 or 3 hours of the bite; extreme envenomation may require amputation of the limb and subsequent reconstructive surgery, rehabilitation, and physical therapy .