Tachycardia coffee

When use of the CNS stimulants causes insomnia, the nurse administers the drug early in the day (when possible) to diminish sleep disturbances. The patient is encouraged not to nap during the day. Other stimulants, such as coffee, tea, or cola drinks, are avoided. In some patients, nervousness, restlessness, and palpitations may occur. The vital signs are checked every 6 to 8 hours or more often if tachycardia, hypertension, or palpitations occur. Many times these adverse reactions will diminish with continued use as tolerance develops. If tolerance develops, the dosage is not increased. 

Extremely heavy coffee drinkers often have tachycardia and extrasystoles. 

A cnp of coffee can contain 50-150 mg of caffeine, and cola drinks can have 35-55 mg. Theophiline,l,3-dimethylxanthine, a principal, characteristic alkaloid of tea, and theobromine, 3,7-dimethylxanthine (23.3.19), a principal alkaloid of cocoa, are among a number of methylxanthines. In small doses, caffeine is a relatively weak psychostimulant and is used for increasing awareness as well as for relieving headaches associated with blood flow disorders of the brain. Caffeine has a stimulatory effect on the respiratory and vasomotor centers, and it stimnlates centers of the vagus nerve. It has a direct stimulatory effect on the myocardium, and in large doses can cause tachycardia and arrhythmia. 

Cardiovascular system. Both caffeine and theophylline directly stimulate the myocardium and cause increased cardiac output, tachycardia and sometimes ectopic beats and palpitations. This effect occurs almost at once after i.v. injection and lasts half an hour. Theophylline contributes usefuUy to the relief of acute left ventricular failure. There is peripheral (but not cerebral) vasodilatation due to a direct action of the drugs on the blood vessels, but stimulation of the vasomotor centre tends to counter this. Changes in the blood pressure are therefore somewhat unpredictable, but caffeine 250 mg (single dose) usually causes a transient rise of blood pressure of about 14/10 mmHg in occasional coffee drinkers (but has no additional effect in habitual drinkers) this effect can be used advantageously in patients with autonomic nervous system failure who experience postprandial hypotension (2 cups of coffee with breakfast may suffice for the day). In occasional coffee drinkers 2 cups of coffee (about 160 mg caffeine) per day raise blood pressure by 5/4 mmHg. Increased coronary artery blood flow may occur but increased cardiac work counterbalances this in angina pectoris. 

Cuffeine is extracted from tea dust and during coffee roasting, caffeine sublimes. Caffeine has above all a centrally stimulant (analeptic) effect on the cerebrum, produces tachycardia and has a diuretic effect. 

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