|Year : 1970 | Volume
| Issue : 3 | Page : 131-134
Anaesthesia in ophthalmology
AH Dastoor, S Bhomisa, H Mobedji
A H Dastoor
|How to cite this article:|
Dastoor A H, Bhomisa S, Mobedji H. Anaesthesia in ophthalmology. Indian J Ophthalmol 1970;18:131-4
Apart from surgical skill, the ultimate success of an intra-ocular operation greatly depends upon the mode of anaesthesia. The purpose of anaesthesia is to relieve pain, anxiety and apprehension and, if possible, to produce muscular relaxation. Emotional states cause a severe, generalized increase of muscular tone, which affects the orbicularis and extraocular muscles and produces a tendency to hold the breath, causing severe congestion. General anaesthesia combined with local akinesia and retrobulbar anaesthesia seems to accomplish this purpose. Another advantage of general anaesthesia is the peace of mind brought to the surgeon who can concentrate on his surgery. Moreover the average surgeon's performance is vastly improved when he no longer has to worry about the possible reactions of his patient on the table and when he can plan his technique unhurriedly and carefully. To achieve best results, the anaesthesia must be safe and smooth with minimal postoperative complications.
Minor surgery like removal of foreign bodies from the cornea or removal of stitches following an intraocular operation requires local anaesthesia. Instillation of Lignocaine Hydrochloride 4% or Amethocaine Hydrochloride 2% eye-drops usually suffices to anaesthetize temporarily. This will give analgesia of the cornea and conjunctiva, but not of the iris or ciliary body. Apart from the initial smarting sensation on instilling these eve-drops, the patient as a rule is usually co-operative. Similarly transplantation of a Pterygium or excision of a Chalazion of the eye-lid requires an injection of 4 nil. Lignocaine Hydrochloride 2% solution. In apprehensive patients it may be necessary to sedate earlier by a tranquilizer like Hydroxyaine Hydrochloride I tablet of 50 mgm, or Oxazcpam I tablet of 15 mgm. Where deeper sedation is required Chlorpromazine Hydrochloride 1 tablet of 10 mgm. or 25 morn., or Triflupromazine Hydrochloride l tablet of 10 mgm. may be administered, depending upon the general constitution and build of the patient and after confirming that the patient is not hypotensive.
The conventional and most popular mode of anaesthesia for intra-ocular operations is by local injections and local eye-drops. In this series, 50 cases were operated upon under local anaesthesia, of which 40 were Cataract extractions, 8 glaucoma iridectomy or iridiencleisis, and 2 squints in adults. This anaesthesia is obviously contraindicated in children and in elderly, apprehensive, obese patients. Preoperative sedation is administered as in the case of minor surgery about an hour before operation and the patient is brought to the operation table preferably on a stretcher. Lignocaine 4% eye-drops are instilled for local analgesia. An injection of 4 nil. Lignocaine 2% is given at the temporomandibular joint, to anaesthetize the branches of the Facial (VII) nerve, and subsequently a retro-bulbar injection of 2 nil. Lignocaine 2% to anaesthetize the ciliary ganglion. Two patients were sensitive to the drug and experienced a sinking feeling with air hunger and hypotension. Suitable resuscitative measures were immediately adopted and the patients were revived but surgery postponed. In spite of adequate pre-operative sedation several patients were apprehensive and non-cooperative; the application of eye-lid stitches or the suture of the rectus oculi superior muscle being painful. Five patients undergoing cataract surgery were unusually apprehensive and rowdy, producing Vitreous loss although the operations were completed successfully and multiple stitches applied at the limbus cornea. Three patients had sudden hypotension on the operation table prior to surgery, which was probably due to walking into the theatre; once the blood pressure was stabilized, surgery was completed. Such complications may altogether be avoided by adopting general in preference over local anaesthesia except where contraindicated like (1) respiratory tract infections (2) severe anaemia (3) gross pulmonary disease (4) myocardial ischaemia (5) congestive cardiac failure, and (6); muscular dystrophies.
To assess the results of operations under general anaesthesia, 100 cases were: operated upon by the classical method of induction with intravenous Thiopentone Sodium, followed by Succinylcholine Chloride as muscle relaxant and endotracheal intubation maintaining the patient on a mixture of Nitrous Oxide, Oxygen, Trilene and occasionally Ether when the cautery was not used for surgery. Owing to the fairly high incidence of postoperative complications of cough, nausea and vomiting, 100 cases were operated upon under general anaesthesia eliminating endotracheal intubation and all gases except Oxygen. In this method, pre-operative `heavy sedation' or a combination of injections was administered intramuscularly. Altogether under general anaesthesia, 175 cases were cataract extractions, 13 glaucoma operations, 4 dacryocystectomies, 3 squints, 3 discissions for bilateral juvenile cataracts and 2 enucleations of the eye-ball.
General anaesthesia with endotracheal intubation
A pre-operative injection of an anticholinergic agent Atropine Sulphate 0.6 mgm. was given one hour before surgery, and orally 25 to 30 drops of Chlophedianol Hydrochloride or "Detigon" was given a half-hour earlier. "Detigon" serves as a powerful antitussive agent and has both central and local actions in preventing postoperative cough for about 3 hours. The patient was then induced with minimal quantities of Thiopentone Sodium intravenous. As soon as the patient was unconscious, Succinylcholine Chloride was injected 60 to 80 mgm. intra-venously in the amount necessary to produce complete relaxation of the jaw muscles and larynx. Endotracheal intubation was done after inflating the lungs with Oxygen and air and the tube connected to an anaesthetic apparatus. Anaesthesia was maintained by six litre flows of a 60:30 mixture of Nitrous Oxide and Oxygen with Trilene or Ether. Intermittent injections of Thiopentone Sodium were given to a maximum of 1.5 G., carefully noting that there be no significant decrease of intra-ocular pressure and no respiratory depression and maintaining a free air-way. Succinylcholine Chloride raises the intra-ocular pressure because of its contractile effect on the extra-ocular muscles, and should never be injected when actual surgery has begun. During surgery an intravenous injection of Gallamine Triethiodide 80 to 160 mgm. was given as a long acting muscle relaxant. Towards the end of operation an intravenous injection of Atropine Sulphate 0.6 mgm. to 1.2 mgm. followed by Neostigmine Mcthylsulphate 2.5 mgm. slowly till the patient came out of anaesthesia. Neostigmine Methylsulphate reverses the action of Gallamine Triethiodide and produces mucoid secretion which needs removal by a suction apparatus. Post-operative all cases were given a facial block of 4 ml. Lignocaine 2% to prevent squeezing of the eye-lids. Only the operated eye was padded, the other remaining open so that the patient may be spared the ordeal of coming out of anaesthesia in total darkness. The commonest complications noted with this method were post-operative nausea with vomiting in 10 cataract extractions. Application of multiple stitches, injection of facial block and Prochlorperazinc injection 12.5 mgm. intra-muscular helped considerably yet 4 cases developed Iris prolapse, all of which were repaired subsequently, but 2 developed hypopyon and phthisis bulbi. Cough was noted in 8 cases but did no damage. It was obvious that the endotrachcal tube, Trilenc and Ether were responsible for these complications.
General anaesthesia without endo.. tracheal intubation
A pre-operative injection of Atropine Sulphate 0.6 mgm. to 1.2 mgm. was given intramuscularly one hour before surgery. After checking the blood pressure and general condition of the patient, an intramuscular combination injection of the following drugs was given:
1) Pethidine 50 to 75 mgm.
2) Proniethazine 50 mgm.
3) Prochlorperazine 12.5 mgm.
The dose of injection Pethidine was adjusted according to the build of the patient. As before, "Detigon" 25 drops were given orally and the patient brought to the operation table on a stretcher. The patient was induced under anaesthesia by injecting Thiopentone Sodium, the chin elevated and the tongue held by a tongue clip or a metal air-way inserted over the tongue. A thin rubber catheter supplying Oxygen at the rate of 3 to 4 litres per minute from a cylinder was inserted gently through one nostril. A retrobulbar injection of 2 nil. Lignocaine 2% was given in 75 cases and omitted in 25 cases. Surgery was commenced and the patient maintained under anaesthesia by injecting small amounts of Thiopentone Sodium upto a maximum of 1.5 G., constantly keeping a vigil over the blood pressure, respiration, pulse and cardiac rate and the air-way. At the end of surgery a facial block of Lignocaine 2% was given and the patient kept on the operation table till semiconscious. As before only the operated eye was padded. The objection to this method is the risk of a sudden fall in blood pressure during operation and especially during traction on an ocular muscle. Once administered these drugs are out of the anaesthetists' control as distinct from general anaesthesia where the flow rate of the inhalant may be varied. In case of sudden respiratory depression it may be necessary to intubate midway during surgery, This occurred in 1 case of cataract and 1 of glaucoma, though both patients were diabetics and obese. Five cases had a fall of blood pressure on reaching the wards, and were successfully treated. There were no cases of nausea or vomiting, while cough was noted in only 3 cases. There were no complications in any of the 25 cases where the retro-bulbar injection was omitted. However this injection served to lower the intra-ocular pressure and simplify the surgery in the other 75 cases. This method is ideal for intra-ocular operations lasting for 45 minutes to l hour. It is not advisable for prolonged surgery as in Detachment Retina, or Corneoplasty operations.
The prime advantages of induction under general anaesthesia without endotracheal intubation are the ease of administration, no irritant drugs, smooth recovery, safety to life and least post-operative complications. Although not ideal in all cases, this method shows promise and perhaps with modifications in future may prove an asset in ophthalmic surgery.
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