Anticholinergic premedication for infants and children

Should the routine use of atropine before succinylcholine in children be reconsidered?

It is common practice to administer atropine before a first dose of succinylcholine in infants and children. However, the administration of succinylcholine without atropine has not been investigated in children. This study was designed to compare cardiovascular changes after the administration of either atropine with succinylcholine or succinylcholine alone. In 41 ASA I or II patients aged from 1 to 12 yr anaesthesia was induced with thiopentone 5 mg.kg-1. Patients were randomly allocated to receive either atropine 20 micrograms.kg-1 and succinylcholine 1.5 mg.kg-1 (n = 20) or succinylcholine 1.5 mg.kg-1 alone (n = 21). Heart rate and rhythm were recorded continuously from two minutes before induction until two minutes after tracheal intubation. Blood pressure was measured non-invasively before and after induction of anaesthesia and both immediately and two minutes after laryngoscopy. One self-limiting episode of bradycardia was recorded during laryngoscopy in a child who received atropine. Heart rate increased in both groups compared with baseline values (108 +/- 25), with a greater increase in patients who had received atropine (150 +/- 13) than in those who had not (128 +/- 18) (P < 0.05). There was no difference in mean arterial pressure or incidence of arrythmias between the two groups. No recorded arrythmias were judged to be clinically important by a cardiologist. The incidence of bradycardia after succinylcholine in the absence of atropine in children aged from 1 to 12 yr appears to be lower than previously estimated. The use of atropine before a single dose of succinylcholine in children deserves to be reconsidered.

A national survey of atropine use by Australian anaesthetists

All Fellows of the Faculty of Anaesthetists, Royal Australasian College of Surgeons (now Australian and New Zealand College of Anaesthetists) were surveyed by mail regarding their use of prophylactic atropine. They were asked whether their usual practice was to give atropine for the following indications: premedication, induction of anaesthesia, intubation of the trachea, one dose of suxamethonium, a second dose of suxamethonium, halothane anaesthesia, oropharyngeal surgery, bronchoscopy and eye surgery. For each indication they were asked for details regarding their practice concerning neonates, infants, children and adults. The large response rate of 86% of Fellows returning a survey form ensured that the survey was representative of Australian anaesthetic practice. Results indicate a wide variation in practice regarding the prophylactic use of atropine, with neonates, infants and children more likely to receive prophylactic atropine than adults. The majority do not give prophylactic atropine as premedication, but may give it in the younger age groups at induction, and many (67%) only give it if they are to administer suxamethonium to a child. The only indication for which a convincing majority (> 80%) of anaesthetists agreed that prophylactic atropine should be given was when a repeated dose of suxamethonium was to be given to neonates, infants or children. A large proportion of anaesthetists (> 80%) agreed that atropine is not necessary prior to halothane anaesthesia in all age groups, nor as premedication, at induction, at intubation, prior to oropharyngeal surgery or prior to eye surgery in adults. These results were compared with the practice at a major paediatric hospital where the practice is not to use routine prophylactic atropine.

Principles of ophthalmic anesthesia

Ophthalmic surgery presents the anesthesiologist with many unique challenges. The exigencies of this subspecialty include a comprehensive knowledge of ocular physiology and pharmacology and an understanding of the anesthetic implications intrinsic to a wide variety of ophthalmic procedures.

Intraocular pressure--physiology and implications for anaesthetic management

The major factors controlling intraocular pressure during surgery are the dynamic balance between aqueous humour production in the ciliary body and its elimination via the canal of Schlemm; the auto-regulation and chemical control of choridal blood volume; the extraocular muscle tone and vitreous humour volume. Prior to surgical incision of the anterior chamber in open intraocular procedures, a low-normal intraocular pressure is mandatory to avoid the hazards of iris or lens prolapse and vitreous loss associated with sudden decompression. In general, the central nervous system depressant drugs, hypnotics, narcotics, major tranquillizers, volatile anaesthetic agents are associated with a reduction in intraocular pressure, with the exception of ketamine and possibly trichloroethylene. The mechanism of action of anaesthetic agents in reducing intraocular pressure may involve a direct effect on central diencephalic control centres, reduction of aqueous production, facilitation of aqueous drainage or relaxation of extraocular muscle tone. Succinylcholine administration is associated with a significant rise in intraocular pressure, with a peak increase between two to four minutes following administration and a return to base line values after six minutes. The intraocular hypertensive effect may be due to a tonic contraction of the extraocular muscles, choroidal vascular dilatation or relaxation of orbital smooth muscle. Despite many claims to the contrary, no reported method to date has been shown to consistently prevent the intraocular hypertensive response to intravenous succinylcholine administration. Because the non-depolarizing relaxants are associated with a reduced intraocular pressure, a barbiturate-non-depolarizing relaxant technique utilizing preoxygenation and cricoid pressure has evolved as the most commonly employed induction technique for the emergency repair of a penetrating eye injury. The alternative non-depolarizing relaxant pretreatment-barbiturate-succinylcholine technique may offer the advantages of more rapid onset of relaxation with only minor increases in intraocular pressure and in a carefully controlled rapid sequence induction technique may be the most acceptable method of handling emergency penetrating eye injuries.

The management of anaesthesia for patients with cystic fibrosis

The clinical problems of patients with cystic fibrosis who require anaesthesia are reviewed. The management and the complications of anaesthesia in 77 patients over a 3-year period are presented. The long term effects of anaesthesia are analysed by a study of the lung function tests of these patients. The results suggest that even multiple procedures, as for instance nasal polypectomy, are not harmful. A method for safe peroperative management is presented.