Bradycardia atropine

Overdosage of carvedilol results mainly in hypotension and bradycardia (2). For excessive bradycardia, atropine has been used successfully, while to support ventricular function intravenous glucagon, dobutamine, or isoprena-line have been recommended. For severe hypotension, adrenaline or noradrenaline can be given. 

Supraventricular bradycardia is treated by implantation of a pacemaker device or has been treated pharmacologically with atropine. Supraventricular paroxysmal tachycardia is treated with aj marine or praj marine. Supraventricular tachyarrhythmias or AV reentrant arrhythmia typically can be terminated using adenosine. 

Cardiovascular system—palpitations, bradycardia (after low doses of atropine), tachycardia (after higher doses of atropine)... 

If pronounced bradycardia occurs, the primary heal til care provider may order emergency measures, such as die administration of IV atropine (see Chap. 25) or isoproterenol (see Chap. 22). Any sudden change in mental state should be reported to the primary health care provider immediately because a decrease in die dosage may be necessary. 

Anticholinergic treatment (atropine derivatives) may sometimes be indicated, especially in patients with pronounced bradycardia. 

Consider glucagon 2-10 mg IV bolus followed by a 2-10 mg/h continuous IV infusion in P-adrenergic blocker or calcium channel blocker-induced bradycardia not responsive to atropine... 

Acute treatment of patients with second- or third-degree AV nodal blockade consists primarily of administration of atropine, which maybe administered in the same doses as recommended for management of sinus bradycardia. In patients with hemodynamically unstable or severely symptomatic AV nodal blockade that is unresponsive to atropine and in whom temporary or transvenous pacing is not available or is ineffective, epinephrine (2 to 10 mcg/minute, titrate to response) and/or dopamine (2 to 10 mcg/kg/minute) maybe administered.14... 

Muscarine, an alkaloid from certain species of mushrooms, is a muscarinic receptor agonist. The compound has toxicologic importance muscarine poisoning will produce all of the effects that are associated with an overdose of ACh (e.g., bronchocon strict ion, bradycardia, hypotension, excessive salivary and respiratory secretion, and sweating). Poisoning by muscarine is treated with atropine. 

Atropine generally increases heart rate, but it may briefly and mildly decrease it initially, due to Ml receptors on postganglionic parasympathetic neurons. Larger doses of atropine produce greater tachycardia, due to M2 receptors on the sinoatrial node pacemaker cells. There are no changes in blood pressure, but arrhythmias may occur. Scopolamine produces more bradycardia and decreases arterial pressure, whereas atropine has little effect on blood pressure (Vesalainen et al. 1997 Brown and Taylor 1996). 

Sinus bradycardia. An abnormally low sinoatrial impulse rate (<60/min) can be raised by parasympatholytics. The quaternary ipratropium is preferable to atropine, because it lacks CNS penetrability (p. 107). Sympathomimet-ics also exert a positive chronotropic action they have the disadvantage of increasing myocardial excitability (and automaticity) and, thus, promoting ectopic impulse generation (tendency to extrasystolic beats). In cardiac arrest epinephrine can be used to reinitiate heart beat... 

In sinus bradycardia or incomplete heart block, lidocaine administration for the elimination of ventricular ectopy without prior acceleration in heart rate (eg, by atropine, isoproterenol or electric pacing) may promote more frequent and serious ventricular arrhythmias or complete heart block. Use with caution in patients with hypovolemia and shock, and all forms of heart block. 

Cardiovascular effects During evaluation of nalbuphine in anesthesia, a higher incidence of bradycardia has been reported in patients who did not receive atropine preoperatively. 

Sradycard/a Atropine is used in the suppression of vagally mediated bradycardias. Preoperative medication Atropine, scopolamine, hyoscyamine, and glycopyrrolate are used as preanesthetic medication to control bronchial, nasal, pharyngeal, and salivary secretions and to block cardiac vagal inhibitory reflexes during induction of anesthesia and intubation. Scopolamine is used for preanesthetic sedation and for obstetric amnesia. 

Uses t CO in bradycardia refractory to atropine Action Pi- stimu-... 

O2, IV fluid, pressors, cyanide antidote kit, Cyanokit, sodium bicarbonate, anticonvulsants for Szs O2, charcoal, atropine (bradycardia), antiar-rhythmic (lidocaine, amiodarone)... 

Sinus rhythm with a rate of less than 60/min is defined as sinus bradycardia. This bradycardia is usually a physiological response. Pathological and/or symptomatic sinus bradycardia may suggest sinus node dysfunction (see sick sinus syndrome). Vagally induced sinus bradycardia may be responsive to atropine, but only needs to be treated if symptomatic. Atropine doses of less than 0.5 mg may cause a paradoxical increase in vagal bradycardia. 

The reflex nature of the bradycardia induced by parenterally administered norepinephrine can readily be demonstrated by administration of atropine, a choli-noreceptor antagonist. Atropine abolishes the compensatory vagal reflexes. Under conditions of vagal blockade, the direct cardiac stimulatory effects of norepinephrine are unmasked. There is marked tachycardia, an increase in stroke volume, and as a consequence, a marked increase in cardiac output (Fig. 10.4). 

B. Phenylephrine is an aj-selective agonist. It causes an increase in peripheral vascular resistance. The major cardiovascular response to this drug is a rise in blood pressure associated with reflex bradycardia. The slowing of the heart rate is blocked by atropine. 

Atropine can be useful in patients with carotid sinus syncope. This condition results from excessive activity of afferent neurons whose stretch receptors are in the carotid sinus. By reflex mechanisms, this excessive afferent input to the medulla oblongata causes pronounced bradycardia, which is reversible by atropine. 

Atropine can be used in the differential diagnosis of S-A node dysfunction. If sinus bradycardia is due to extracardiac causes, atropine can generally elicit a tachy-cardic response, whereas it cannot elicit tachycardia if the bradycardia results from intrinsic causes. Under certain conditions, atropine may be useful in the treatment of acute myocardial infarction. Bradycardia frequently occurs after acute myocardial infarction, especially in the first few hours, and this probably results from excessive vagal tone. The increased tone and bradycardia... 

The administration of angiotensin II to an animal with intact baroreceptor reflexes results in reflex bradycardia in response to the marked vasoconstriction. When baroreceptor reflexes are depressed (barbiturate anesthesia) or if vagal tone is inhibited (atropine or vagotomy), angiotensin directly induces cardiac acceleration. 

Overdose may result in cholinergic crisis, characterized by severe nausea, increased salivation, diaphoresis, bradycardia, hypotension, flushed skin, abdominal pain, respiratory depression, seizures, and cardiorespiratory collapse, increasing muscle weakness may result in death if respiratory muscles are involved. The antidote is 1 -2 mg IV atropine sulfate with subsequent doses based on therapeutic response. 

Overdose can cause cholinergic crisis, marked by increased salivation, lacrimation, bradycardia, respiratory depression, hypotension, and increased muscle weakness. Treatment usually consists of supportive measures and an anticholinergic such as atropine. 

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