|Year : 1981 | Volume
| Issue : 1 | Page : 5-8
Sustained intraocular tension during reversal of general anaesthesia
P Chari, J Sood
Department of Anaesthesia, Postgraduate Institute of Medical Education and Research, Chandigarh, India
8H/5, Sector 12 Chandigarh-160012
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Chari P, Sood J. Sustained intraocular tension during reversal of general anaesthesia. Indian J Ophthalmol 1981;29:5-8
It is important to maintain intraocular pressure (I.O.P.) at normal or reduced levels during intraocular surgery. Any increase in I.O.P. while the eyeball is open may result in vitreous prolapse with subsequent loss of vision. I.O.P. falls during smooth general anaesthesia but coughing and straining on the endotracheal tube causes an increase in I.O.P. The benefit of non-depolarising muscle relaxants in small doses to the conscious and spontaneously breathing patient during operation under local analgesia has been described earlier. Increase in I.O.P. with the use of suxamethonium and increase in suxamethonium induced intraocular hypertensive effect with intubation has also been documented. There are different views regarding the taming of the suxamethonium induced increase in I.O.P. with a prior injection of smaller dose of non-depolarizing muscle relaxants., The usual practice of bandaging of the operated eye with the endotracheal tube in situ involves repeated lifting of the head of the patient. This leads to straining of the patient on the tube which in turn may lead to increased I.O.P.
This study was undertaken to see the effect on I.O.Y. with the use of non-depolarising muscle relaxants and local Xylocaine spray on larynx for intubation. Secondly, the effect on I.O.P. while bandaging the eye at the end of surgery have been compared in two groups. In one group bandaging of the eye was done with the endotracheal tube in situ while in the other group it was done after extubation.
| Materials and methods|| |
This study was carried out on 100 healthy adults (25-45 years) posted for elective surgery other than ophthalmic surgery. Patients were premeditated with oral diazepam and intramuscular morphine and Phenergan [Table - 1]. A similar anaesthetic technique was used for both groups, which consisted of thiopentone, non-depolarising muscle relaxants, local spray of the larynx with 4% Xylocaine, oxygen, nitrous oxide and incremental dose of intravenous morphine. Patients were ventilated with Manley ventilator. At the end of the operative procedure, the effect of non-depolarising muscle relaxants were reversed with prostigmin and atropine.
Out of 100 patients, fifty patients received tubocurarine and fifty received gallamine as muscle relaxants. In part one of the study, these two groups were compared. All E.O.P. measurements were made at the same time intervals in both the groups [Figure - 1],[Figure - 2]. I.O.P. was measured with Schiotz indentation tonometer (5.5 gm. wt.) after using 4 Xylocaine drops as topical anaesthetic in the eye. Basal I.O.P. was taken a day prior to the surgery. On the day of surgery, measurements were taken an hour after premedication, and at 1, 2, 7, 12 and 17 minutes after induction. In part two of the study, each group of fifty patients were further divided to bandage first group and extubation first group [Table - 2]. In the bandage, first group after the operation, the eye was bandaged, first and then the suction, reversal of the effect of the muscle relaxants, and the extubation of the tube was done. In extubation first group after the operation, patients were breathed with 100% oxygen for 3-5 minutes, then suction of the throat was done. After the removal of the endotracheal tube, reversal drugs were administered and then the bandaging of the eye was done. After the application of the bandage, I.O.P. was measured on the non-bandaged eye.
In the second part of the study, I.O.P. measurements were taken at various incidents [Table - 2] like after extubation after suction, after reversal, bandaging of the eye and five minutes after the end of the procedure.
Pulse rate and the blood pressure was measured with an oscillotonometer at the same time as each I.O.P. was measured in the majority of the patients.
| Observations|| |
In both groups age, sex and basal I.O.P. were comparable. At induction, after injection of muscle relaxants and thiopentone, the I.O.P. decreased. At intubation, the I.O.P. rose but remained lower than the basal value. Thereafter till the end of the operation, I.O.P. remained stable. There was no statistical difference between tubocurarine group and gallamine group. [Figure - 1] & [Figure - 2].
In part two of the study [Table - 2],[Figure - 3], it was observed that I.O.P. rose significantly high (P<.001) in bandage first group at the time of bandaging of the eye whereas in extubation, first group at this time, it rose to only 1 mm Hg. Similarly, in bandage first group, the I.O.P. remained significantly high (P<0.01-0.001) during all the incidents whereas in extubation first group, the I.O.P. remained stable till the end. In both group, the changes in the pulse rate and arterial pressure were not significant.
| Discussion|| |
The basic essential for all intraocular surgery is a meticulously smooth, flawless anaesthetic technique with avoidance of coughing, straining or vomiting and adequate, unimpeded ventilation of the lungs. The use of morphine gave good analgesia. Phenergan and diazepam antagonized the emetic effect of morphine. Thiopentone with non-depolarising muscle relaxant lowered the I.O.P. during induction. At the time of intubation though there was a rise in I.O.P., it was still lower than the basal value [Figure - 1],[Figure - 2].
Pandey et a1 supported the views of Wynands and Growell that endotracheal intubation increased the intraocular hypertensive effect of suxamethonium and local analgesia did not prevent this rise. In our study, use of non-depolarising muscle relaxants with 4% lignocaine spray locally prevented significant rise of I.O.P. at the time of intubation. We did not find any significant difference in the changes of I.O.P. with Tubarine and with that of gallamine.
It used to be the practice to maintain deep anaesthesia until after extubation to prevent coughing with resultant strain on the suture line and risk of iris prolapse or worse. Taking the patients deep at the end of procedure has its own disadvantages. The prevention of significant rise in I.O.P. at the time of extubation could be done by removing the tube with proper precautions before giving reversal and bandaging the eye after extubation. From our study, one can see that in bandage first group [Figure - 3], there was significant rise in I.O.P. The frequent lifting of the head with the endotracheal tube in situ results in straining by the patient which is the cause for rise in I O.P. at this stage. In the extubation first group, there was no significant rise in I.O.P. during all the incidents. This confirms that a smooth reversal followed by bandaging of the eye after extubation helps to prevent the significant rise of I.O.P.
As far as arterial pressure is concerned, minor changes have little effect on I.O.P. Adam and Barnett have shown that only fall below 90 mm Hg. of arterial pressure will lower the I.O.P. significantly.
| Summary|| |
The changes in I.O.P. during intubation and reversal of anaesthetics in 100 healthy patients coming for elective nor-ocular surgery was studied. Non-depolarising muscle relaxants with local analgesia was used to facilitate intubation. This technique prevented the significant rise in I.O.P. during intubation. At the time of reversal, the I.O.P. rose significantly high when bandaging of the eye and suction of the throat was done with the endotracheal tube in situ. Suction of the throat and extubation before reversing the patient prevents significant rise in I.O.P. Bandaging of the eye after extubation has been found to be better as it keeps the 1.0-P. stable during reversal and in the immediate post-operative period.
| References|| |
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[Figure - 1], [Figure - 2], [Figure - 3]
[Table - 1], [Table - 2], [Table - 3]