Printer Friendly

Caution with ocular phenylephrine.

Phenylephrine is a sympathomimetic agent which acts primarily as an alpha adrenergic agonist. Systemically administered phenylephrine is a powerful vasoconstrictor, which can cause profound haemodynamic changes. Topical phenylephrine solutions are widely used in ophthalmic surgery, both for capillary vasoconstriction and for pupillary dilatation. Ophthalmic phenylephrine is rapidly systemically absorbed through the nasolacrimal system and may have undesired side-effects.

This communication describes a severe hypertensive crisis after topical ocular phenylephrine in a healthy two-year-old child undergoing bilateral squint surgery. With the patient under general anaesthesia, the surgeon applied phenylephrine drops to an eye to reduce hyperaemia. There was an immediate rise in blood pressure (measured non-invasively) to 210/146 mmHg. The hypertension was controlled with increased sevoflurane concentration and boluses of propofol, and returned to acceptable levels within minutes. The eye-drops were rechecked and found to be 10%, the usual concentration used in an adult cataract surgery and not 2.5% as would normally be used for a child. Although this patient recovered uneventfully, an episode of hypertension such as this could result in cardiovascular complications such as acute myocardial failure, pulmonary oedema, intracranial haemorrhage and cerebral oedema.

Infants may develop higher systemic levels from eye-drops compared to adults due to a possible smaller tear film volume and a less mature metabolic system (1). Although serious morbidity associated with hypertension may be uncommon in the paediatric age group following systemic absorption of ocular phenylephrine, pulmonary oedema and cardiac arrhythmias have been reported in an eight-year-old boy after an iatrogenic hypertensive crisis following 10% phenylephrine (2). The concomitant use atropine with associated tachycardia can exacerbate the pressor effects of phenylephrine (and prevent appropriate baroreceptor induced bradycardia), especially in infants. The presence of specific paediatric conditions, such as a left to right shunt (e.g. patent ductus arteriosus) or low birthweight and prematurity may make adverse outcomes more likely.

Various measures to decrease the systemic absorption and associated haemodynamic effects of ophthalmic phenylephrine have been suggested. The use of the 2.5% solution is recommended rather than the 10% solution as both strengths of phenylephrine are equipotent mydriatrics in most patients (3). Other measures include devices to deliver smaller drops, occlusion of the nasolacrimal punctum and blotting away excess drops after drug administration. It has been suggested that the practice of using a 10% solution either by irrigation with a conjunctival pledget or injection subconjunctivally should be discouraged (4).

Although general anaesthetic agents are effective, rapidly titratable and readily available for control of hypertension in these cases, there is some risk that the negative ionotropic effects of these agents, in the presence of dramatically increased afterload, could exacerbate cardiac failure. Less readily available but more specific treatment could be provided with a short-acting alpha adrenergic antagonist such as phentolamine or other short acting vasodilators.

Anaesthetists should be aware of the possible adverse reactions to topical phenylephrine even if a 2.5% solution is used and not underestimate the systemic absorption of these topical drugs, especially in children. It may be preferable to give topical mydriatic drugs 30 to 60 minutes prior to induction of general anesthesia to assess adequacy of mydriasis before induction (5). It has also been observed that the majority of the adverse effects to these agents occur within the first 20 to 30 minutes following topical application. Blood pressure should be monitored during this time (6) and throughout the surgery in all anaesthetized patients.

References

(1.) Lynch MG, Brown RH, Goode SM, Schoenwald RD, Chien DS. Reduction of phenylephrine drop size in infants achieves equal dilation with decreased systemic absorption. Arch Ophthalmol 1987;105:1364-1365.

(2.) Baldwin FJ, Morley AE Intraoperative pulmonary oedema in a child following systemic absorption of phenylephrine eyedrops. Br J Anaesth 2002; 88:440-442.

(3.) Malhotra R, Banerjee G, Brampton W, Price NC. Comparison of the cardiovascular effects of 2.5% phenylephrine and 10% phenylephine during ophthalmic surgery. Eye 1998; 12:973975.

(4.) Fraunfelder FT, Scafidi AE Possible adverse effects from topical ocular 10% phenylephrine. Am J Ophthalmol 1978; 85:447453.

(5.) VanDerSpek AFL, Hantler CB. Phenylephrine eyedrops and anesthesia. Anesthesiology 1986; 64:812-814.

(6.) Kumar V, Schoenwald RD, Barcellos WA, Chien DS, James CF, Weingeist TA. Aqueous vs viscous phenylephrine 1. Systemic absorption and cardiovascular effects. Arch Ophthalmol 1986; 104:1189-1191.

U. GURUNATHAN

Wagga Wagga, New South Wales
COPYRIGHT 2006 Australian Society of Anaesthetists
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2006 Gale, Cengage Learning. All rights reserved.

Article Details
Printer friendly Cite/link Email Feedback
Title Annotation:Correspondence
Author:Gurunathan, U.
Publication:Anaesthesia and Intensive Care
Date:Oct 1, 2006
Words:713
Previous Article:Bispectral index guided timing of intubation without neuromuscular blockade during sevoflurane induction of anaesthesia in adults.
Next Article:Asystole during percutaneous ethanol injection of symptomatic vertebral haemangioma.


Related Articles
BICI to Install Capacity at its Facility in Petersburg, Va., to Meet the Fast-Growing Demand for Phenylephrine.
Cold remedy alternatives have their drawbacks.
Pharmacologic reversal of Horner's syndrome-related ptosis with apraclonidine.
Unilateral mydriasis and hypertensive crisis during nasal surgery.

Terms of use | Copyright © 2017 Farlex, Inc. | Feedback | For webmasters