Atropine anesthesia

Drug solutions and implantation of osmotic mini-pumps Physostigmine hemisulphate and procyclidine hydrochlorid were obtained from Sigma (St.Louis, U.S.A.), scopolamine hydrobromid from Merck (Darmstadt, Germany), atropine sulphate was obtained from ACF (Amsterdam, The Netherlands), and diazepam from Roche (The Netherlands). HI-6 was made available by the Defence Research Establishment, Suffield, Canada. Soman (O-pinacolyl methylphosphonofluoridate) was synthesised at TNO. Alzet Osmotic Mini-pumps with a constant delivery rate of 0.55 pl/hr (Model 2002, Alza Corp., Palo Alto, USA) were used to deliver PYR, PHY and SCO. The vehicle consisted of 20% propylene glycol, 10% ethanol and 70% water. The pumps were implanted subcutaneously under isoflurane/02 inhalation anesthesia. 

At least 1 week after their arrival, the rats are given atropine sulfate (0.4 mg/kg, i.p.) and anesthetized with sodium pentobarbital (50 mg/kg i.p.) or isoflurane gas (5%). When necessary, supplemental doses of sodium pentobarbital are given or isoflurane gas is adjusted to maintain anesthesia. The rats are hydrated with 0.9% saline (3.0 cc, s.c.) and given penicillin (0.05 cc 1500 units, i.m.). 

Bronchial secretion. Premedication with atropine before inhalation anesthesia prevents a possible hypersecretion of bronchial mucus, which cannot be expectorated by coughing during intubation (anesthesia). 

Atropine is frequently used during anesthesia in surgery. The main goal is to minimize secretion in the bronchi and nasopharynx, which can impede respiration. In cases where additional sedative action is needed, scopolamine is preferred. 

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. 

Atropine and other drugs from this group has been a standard preoperative adjuvant therapy in general anesthesia since they inhibit the reflex increase of bronchial secretion due to mechanical irritation (intubation) and volatile anaesthetics. 

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. 

A 77-year-old man is admitted to the hospital for a coronary artery bypass. He has been treated with a (3-blocker (Tenormin 100 mg per day), which he took every morning. He is induced with propofol 1 mg/kg, fentanyl 5 jjig/kg and vecuronium 8 mg for muscle relaxation. After 3 minutes a decreasing heart rate becomes a worry for the anesthesiologist. The heart rate continues to fall until it reaches 38 BPM. At this point the patient s blood pressure is 80/60 and the anesthesiologist gives atropine 0.4 mg and ephedrine 10 mg. This treatment results in a stable patient. What effects were most likely produced by the anesthesia procedure Could this have been avoided ... 

Anesthetic techniques that have minimized adverse effects include the use of muscle relaxants and, more recently, nerve stimulators to assess adequacy of relaxation, the introduction of very rapid acting, short-duration barbiturates, and the use of atropinic agents to minimize the cardiovascular response to a combination of a seizure and anesthesia (93). In addition, 100% oxygenation (adequacy monitored by a pulse oximeter) with positive-pressure ventilation can minimize related cardiac events and memory disruption. 

Anticholinergics Prevent excessive salivation and respiratory tract secretions Atropine Glycopyrrolate Scopolamine Oral 2 mg IM 0.2-0.6 mg 30 to 60 minutes before surgery IM 0.0044 mg/kg body weight 30 to 60 minutes before induction of anesthesia IM 0.2-0.6 mg 30 to 60 minutes before induction of anesthesia... 

The pharmacology and adverse effects of midazolam in infants and children have been reviewed (4). The optimal dose of intramuscular midazolam for preoperative sedation has been studied in a double-blind prospective study of 600 patients who were age-stratified (51). The patients received intramuscular atropine 0.6 mg and one of five doses of midazolam 15 minutes before induction of anesthesia. For the age groups 20-39, 40-59, and 60-79 years, the optimal sedative and amnesic effects of midazolam were 0.10, 0.08, and 0.04 mg/kg respectively. The frequency with which the undesirable adverse effects of reduced blood pressure, oxygen desaturation, oversedation, loss of eyelash reflex, and tongue root depression occurred increased with age, and optimal doses for a low incidence of adverse effects were 0.08, 0.06, and 0.04 mg/ kg in the same age groups respectively. 

Despite the reputation of scopolamine for causing amnesia. Hardy and Wakely (124) found that only 13 of 100 patients given subcutaneous injections of l osclne at about 6.3 Mg/kg and morphine at about 157.2 vg/kg had any amnesia of being shown a card Just before Induction of anesthesia. Only seven of these patients had complete amnesia of preoperative events. When atropine at about 9.4 ug/kg was substituted for scopolamine In the preanesthetlc mixture, only one of 100 patients had partial amnesia of belxig shown a card before Induction of anesthesia. 

Belladonna, also called deadly nightshade, gets its name from its ability to dilate the pupils of the eyes. In the past women used belladonna for this purpose because they felt it made them more attractive. The word means beautiful lady in Italian. The plant is a mediumsized herb with long, dark green leaves and small purple flowers. The alkaloids in the plant come from the leaves and the root. Scopolamine and atropine are the main substances used from belladonna in medicine. They have been used as analgesics, anesthesia, and are especially useful in examining eyes. Atropine is also an antidote for some poisons. 

Transient central blindness has followed an intravenous injection of atropine 0.8 mg in the course of spinal anesthesia blink reflex and pupillary response to light and accommodation were lost vision returned slowly after some hours after the instillation of pilocarpine (6). 

Allen GD, Everett GB, Kennedy WF Jr. Cardiorespiratory effects of general anesthesia in outpatients the influence of atropine. J Oral Surg 1972 30(8) 576-80. 

An 86-year-old man, who was taking captopril 25 mg bd and bendroflumethiazide 25 mg/day for hypertension, had a transurethral resection of the prostate under spinal anesthesia, and developed profound bradycardia and hypotension with disturbances of consciousness during transfer to the recovery room (18). Initial treatment with atropine produced rapid improvement in cardiovascular and cerebral function. A further hypotensive episode, without bradycardia, occurred about 1 hour later, but responded rapidly to methoxamine. He made a full recovery overnight. 

In a double-blind, randomized, controlled study of 77 children undergoing halothane anesthesia for adenoidect-omy, the effects of atropine 0.02 mg/kg, glycopyrrolate 0.04 mg/kg, and physiological saline were compared (9). There was no difference in the incidence of ventricular dysrhythmias. Atropine prevented bradycardia but was associated with sinus tachycardia in most patients. The bradycardias that occurred in the groups that received glycopyrrolate or placebo were short-lived and resolved spontaneously. 

Intracardiac conduction disturbances should not be considered as absolute contraindications to epidural anesthesia there were only nine cases of sinus bradycardia, easily reversed with atropine sulfate, in 66 patients (123). However, rare cases of complete heart block and complete left bundle branch block have occurred (SEDA-21, 132) (124). 

A 68-year-old man developed total spinal anesthesia after the administration of 20 ml of ropivacaine 1% without a prior test dose via an epidural catheter, which was inadvertently placed intrathecally (83). Initial aspiration of both the Touhy needle and the catheter failed to identify the intrathecal position of the catheter. The patient noted weakness in his right leg immediately after the end of the injection. This was followed by weakness in his right arm, asystole, apnea, and loss of consciousness. Ventricular escape beats were noted and sinus rhythm returned after mask ventilation with 100% oxygen and the administration of atropine 1 mg and ephedrine 50 mg. He was able to open his eyes, but remained apneic and was therefore intubated and ventilated. Cardiovascular stabihty was maintained with incremental boluses of ephedrine to a total of 60 mg. He regained consciousness and was successfully extubated 145 minutes later. AH sensory and motor deficits had resolved within 8 hours and no neurological deficit or transient neurological symptoms were detected 5 days later. 

In contrast to isoflurane and desflurane, sevoflurane tends not to increase the heart rate, and is usually well tolerated for induction of anesthesia in young children. However, profound bradycardia was reported in four unpremedicated children aged 6 months to 2 years during anesthesia induction with sevoflurane 8% and nitrous oxide 66% (7). The episodes were not associated with loss of airway or ventilation. In three of the children there was spontaneous recovery of heart rate when the sevoflurane concentration was reduced the other child received atropine because of evidence of significantly reduced cardiac output. In a previous study of sevoflurane induction of anesthesia in children with atropine premedication there was also a low incidence of this complication (8), which is probably due to excessive sevoflurane concentrations. 

A 65-year-old woman, who had had normal preoperative serum electrolytes and a normal QT interval with sinus rhythm, received hydroxyzine and atropine premedication followed by thiopental and vecuronium for anesthetic induction. Endotracheal intubation was difficult and precipitated atrial fibrillation, which was refractory to disopyramide 100 mg. Anesthesia was then maintained with sevoflurane 2% and nitrous oxide 50%. Ten minutes later ventricular tachycardia ensued, refractory to intravenous lidocaine, disopyramide, and magnesium. DC cardioversion resulted in a change to a supraventricular tachycardia, which then deteriorated to torsade de pointes. External cardiac massage and further DC cardioversion were initially unsuccessful, but the cardiac rhythm reverted to atrial fibrillation 10 minutes after the sevoflurane was switched off. Two weeks later she had her operation under combined epidural and general anesthesia, with no changes in cardiac rhythm. 

Inhalational agents potentiate muscle relaxants, which is of more clinical importance with regard to non-depolarizing agents. Tachyphylaxis and phase II block develop earlier and after smaller total doses of suxamethonium when volatile agents such as halothane, enflurane, or isoflurane (306,307) are used instead of balanced anesthesia. Halothane can increase the incidence of cardiac dys-rhjdhmias, especially bradycardia and nodal rhythm, after suxamethonium. Atropine and glycopyrrolate, particularly when given intravenously just before, afford some protection (SEDA-5,136) (308). 

Anticholinergic agents are only effective in controlling vagal-mediated bradyarrhythmias and, as such, are usually only used to treat or prevent life-threatening bradycardia during anesthesia. Atropine and glycopyrrolate are used most... 

Atropine may be used to treat some types of arrltythmias. It increases the heart rate hy blocking the effects of ACh on the vagus. In this context, it is used to treat certain reversible hiadyairhythmias that may aceompany aeute myocardial in-raiction. It is also used us an adjunct to anesthesia to protect against bradycardia, hypotension, and even cardiac arrest ittduccd by the skeletal muscle relaxant sueeinylcholine chloride. 

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