Year : 1985 | Volume
: 33 | Issue : 3 | Page : 155--162
Muscle relaxants in relation to intra ocular tension
TZ Khan, Rashid M Khan
Department of Anaesthesiology, J.N. Medical College Aligarh Muslim University, Aligarh, India
T Z Khan
Department of Anaesthesiology, J.N. Medical College Aligarh Muslim University, Aligarh
|How to cite this article:|
Khan T Z, Khan RM. Muscle relaxants in relation to intra ocular tension.Indian J Ophthalmol 1985;33:155-162
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Khan T Z, Khan RM. Muscle relaxants in relation to intra ocular tension. Indian J Ophthalmol [serial online] 1985 [cited 2021 Jun 13 ];33:155-162
Available from: https://www.ijo.in/text.asp?1985/33/3/155/30811
Despite every endeavour made by the anaesthetist to maintain the internal milieu of the eye near normal during anaesthesia, there are anaesthetic agents which tend to change it. One such group of agents are the muscle relaxants. Perhaps succinyoline, which is the most versatile relaxant, is the most abused in this regard due to its tendency to raise intra-ocular tension substantially as a result of sustained contracture of extra ocular muscles. Other relaxants used either alone or as pretreatment agents prior to succinylcholine have also been subject of much discussion. This study analyses the variations in intra ocular tension by 4 commonly used muscle relaxants alone and the modification of the action of succinylcholine in particular by a small pretreatment dose of the above relaxants when administered immediately prior to it. An attempt is also made to find out the best relaxant amongst these 4 relaxants or their combination for intubation purpose with minimal effects on intra ocular tension.
MATERIAL AND METHODS
400 patients undergoing general anaesthesia for non-ophthalmic surgery were included in this study. They belonged to both sexes and their age ranged from 10-78 years. All were classified as A.S.A. Grade I (a normal healthy patient) with haematological and biochemical values within normal range. None of the patients had any evidence of ocular pathology. The patients were divided into 8 groups of 50 patients each according to the muscle relaxant which had been used. These groups were ;
Group. A = Receiving succinylcholine (1.5- 2 mg/Kg) alone.
Group. B = Receiving gallamine triethiodide (2.5-3 mg/Kg) alone.
Group. C = Receiving d-tubocurarine (0.50.6 mg/Kg) alone.
Group. D = Receiving pancuronium bromide (0.08-0.1 mg/Kg) alone.
Group. E = Receiving pretreatment with 5-10 mg succinylcholine, one minute prior to intubating dose of succinylcholine.
Group. F = Receiving pretreatment with 10-20 mg gallamine triethiodide 3 minutes prior to intubating dose of succinylcholine.
Group. G = Receiving pretreatment with 1.5-3 mg d-tubocurarine 3 minutes prior to intubating dose of succinylcholine.
Group. H = Receiving pretreatment with 0.5-1 mg pancuronium bromide 3 minutes prior to intubating dose of succinylcholine.
Premedication consisted of only inj. atropine 3.01 mg/Kg I.M. about 30 minutes before surgery.
Following 3 minutes preoxygenation, anaesthesia was induced with thiopentone sodium 5-7 mg followed by either depolarising or a non-depolarising muscle relaxant as mentioned above to facilitate endotracheal intubation. Following intubation (done after If minutes of full dose of succinylcholine in group A, E, F, G & H while in group B, C, & D it was done 3 minutes after full dose of the relaxant concerned) anaesthesia was maintained with N 2 0 6 lit/min. and 0 3 3 lit/min. supplemented with diethyl ether in a Mapleson "A" anaesthetic system. Intermittent positive pressure ventilation was performed till the return of spontaneous respiration (approximately 7-10 minutes) in Group, A, E, F, G & H or continued or as intermittent positive pressure ventilation in Group B, C & D as the nondepolarizing muscle relaxant administered to these groups have duration of action lasting 20-50 minutes. Throughout this study the patients were placed supine with slight extension of the head and all attempt was made to maintain normocapnia.
Intra ocular tension, pulse & blood pressure were recorded simultaneously at the following time interval-pre-induction (acting as control), after pretreatment, 1 min after induction and then 30 secs., 1½ min, 3 min, 5 min, 7 min & 15 min. after the intubating dose of the concerned muscle relaxant. Intra ocular tension was recorded by a well calibrated schiotz tonometer by the same person throughout this study.
Mean arterial pressure is taken as diastolic pressure plus one third of the pulse pressure.
Following induction with thiopentone sodium there is a fall in intra occular tension significantly. However administration of succinylcholine raises the tension above control value at the 3rd minute interval by an average of 1.24 nim Hg. In gallamine, d-tubocuratine and pancuronium group (B, C & D) intra ocular tension remains persistently below the value at all time interval and the fall is significant [Table 1].
Succinylcholine in subparalytic doses used as pretreatment agent raises intra ocular tension above control value by 2.65 mm Hg. (av.). But other non-depolarizing muscle relaxants in subparalytic doses produce insignificant changes. However, following full dose of Succinylcholine, after pretreatment, intra ocular tension never rose above the control value in any group [Table 2]
The changes in pulse and mean arterial pressure, correspond closely to the intra ocular tension variations [Table 3],[Table 4].
A closed eye will normally withstand a slight increase in intra ocular tension without any trouble but the problem comes in intra ocular surgery or in patients with penetrating injury of the eye undergoing an emergency surgery. In the later in addition to the problem of full stomach the patient will risk impairment or loss of vision as a result of expulsion of intra ocular contents if the anaesthetic is mismanaged and intra ocular tension rises abruptly. Such a situation demands quick smooth intubation without significant fluctuations in intra ocular tension. For ideal intubating conditions succinylcholine is the relaxant of choice but unfortunately it produces a significant rise
in intra ocular tension,,. Adams & Barnett, assign transient dilatation of the choroidal blood vessels as the main cause of increase in intra ocular tension following succinylcholine, while Katz and Eakins explain this by postulating that extra ocular muscle of man contains two separate neuromuscular systems-a twitch and a tonic system. Succinylcho line raises intra ocular tension by stimulating the tonic system of the extra ocular muscle. Whatever be the cause, this rise was evident in this study also, though the rise was insignificant because succinylcholine was administered immediately following thiopentone sodium which lowers the tension significantly due to the relaxation of extra ocular muscle together with an increase in the coefficient of facility of out-flow of aqueous.
Several workers have reported successful taming of succinylcholine induced rise in intra ocular tension by prior administration of subparalytic dose of depolarizing or nondepolarizing muscle relaxant,,,. This is because the subparalytic dose of non-depolarizing muscle relaxant depresses the tonic system of the extra ocular muscle on which succinylcholine acts. Present study also justifies the use of gallamine tr iethiodide, paneuronium bromide and d-tubocurorine 3 minutes prior to succinylcholine to check the rise in intra ocular tension. However results to the contrary are not rare,.
This study however shows the futility of using succinylcholine self pretreatment to check the rise in intra ocular tension. This is because the subparalytic dose of succinylcholine administered before induction raise the tension appreciably. This is contrary to verma's result but in agreement to the findings of Mayer, Singer & Ottol.
Use of non-depolarizing muscle relaxant is not associated with the rise in intraocular tension,, since it depresses both tonic and twitch system. This tallies with our finding. However, in situations where quick relaxation for a hurried intubation is required, non-depolarizing muscle relaxants are at a handicap because of significant delay in onset of full relaxation. With these agents good intubating condititions are not reached before 1½-3 minutes-a period too dangerous in patients with full stomach.
In this study, following intubation the intra ocular tension rose by an average of 3.68 mm Hg as compared to value immediately prior to it. Bannerji, Lala & Mohapatral found that intra ocular tension under succinylcholine increased by 2-9 mm Hg.
Although was have recorded a good correlation between the fluctuations in intra ocular tension and the haemodynamic changes, no cause and effect relationship could be established because all the changes were recorded with either pharmacological or mechanical intervention and not in a steady anaesthetised state.
Atropine as a premedicant in the dosage of 0.01 mg/Kg has not been considered in this study as in this dose it does not have any pharmacologic action on the eye even in patients with acute glaucoma as the total amount of this drug reaching the eye is only 0.001 mng. Utting supports similar view. Also not considered in this study was the effect of IPPR which was done in all cases till the last but one recording. However the last intra ocular tension recording was slightly lower in group B, C & D where IPPR was continued.
We, therefore, recommend succinylcholine as the relaxant of choice for intubation purpose in ophthalmic practice, both for routine and emergency situations. However, it is madatory to pretreat it by subparalytic doses of nondepnlarizing relaxant 3 minutes prior to succinylcholine for optimal control of intra ocular tension.
Effects of different muscle relaxants and their combination on intra ocular tension was evaluated in 400 patients. Succinylcholine was found to raise intra-ocular tension significantly. This could be effectively checked by pretreatment with subparalytic dose of nondepolarizing muscle relaxants 3 minutes prior to succinylcholine. Gallamine triethiodide, d-tubocurarine and pancuronium bromide were found to lower intraocular tension appreciably.
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