|Year : 1989 | Volume
| Issue : 2 | Page : 67-68
Microsurgical instruments and their care
NN Sood, Harsh Kumar
B-1/34, Model Town, Delhi 110 009, India
B-1/34, Model Town, Delhi 110 009
Source of Support: None, Conflict of Interest: None
The microsurgical instruments should be chosen such that they are less than 10cm long, made of titanium, dulled, have very little closing pressure and the working parts do not open more thanl0mm. They should be cleaned with ultrasonic cleaners and sterilised preferably by Ethylene oxide, though Cidex and dry heat can also be used.
|How to cite this article:|
Sood N N, Kumar H. Microsurgical instruments and their care. Indian J Ophthalmol 1989;37:67-8
| Introduction|| |
It was in the 1930's that the operating microscope was introduced in the field of surgery. The initial credit going to Otolaryngiologists. It took another three decades before Peritt in USA used a binocular dissecting microscope for ophthalmic surgery, this being quickly followed by others heralding an era which led to modern day microsurgery.
Microsurgery became popular because it is precison surgery, has minimal tissue trauma, fewer complications, better surgical results, greater professional satisfaction and makes operations possible, which would be otherwise unthinkable. However, it's not without its problems as it is a relatively static surgery, it is done under a narrow field of vision and a narrow depth of focus, it results in loss of points of reference and tactile control, surgeons dependence on a good assistant is increased and it is much more expensive.
For microsurgery to succeed, besides a good microscope and surgical skill, one requires an excellent set of micro-surgical instruments. Microsurgical instruments being quite expensive, their selection and care are a matter of concern to any surgeon who wishes to do well in microsurgery.
For performing a wide range of ophthalmic surgeries one requires only four basic microinstruments namely micro-needle holder, microtoothed forceps with a tying platform, a blade breaker and a Vannas scissors. There are certain characteristics which must be incorporated in any of these microsurgical instruments so that they can be used with ease and can perform minute tasks. Thus they should follow such guidelines such as :
a. Length should be less than 10 cm.
b. Closing pressure should be minimal so as to prevent tremors.
c. Working parts should not open more than 10 mm. and should be dulled to avoid glare.
d. They are preferably made of titanium which is light and durable.
e. One should avoid using a microneedle holder with a catch as it can give jerks which one cannot afford to here during a microsurgical procedure. It should possess a round handle so that it can be rotated easily. The working part should have a gentle curve at 30° to enable it to be held like a pen.
The tying forceps should be toothed with a tying platform the jaws of the tying forceps should come together accurately and the edges should be rounded so that they will not break the sutures. The teeth should also be checked for alignment. McPherson's straight microforceps with a tying platform and dulled surface are adequate for general - purpose such as handling the corneoscleral wound. Angled Colibri toothed forceps with a good curved tying platform prevent the blurred, out of focus shaft obstructing the field that is seen with the straight forceps under the microscope. They can be used to tie even 10-0 nylon. Lim's angled forceps are also equally good.
METHODS OF CLEANING
Cleaning of microsurgical instruments should always be done separately. The cleaning should be entrusted only to senior and experienced technicians / nurses.
Only a fine brush should be used for their cleaning avoiding cloth, a metal scrubber or abrasive. Blood and debris adhering to the working parts is to be removed by washing before it clots. Do not use saline as the washing solution. Distilled water should be preferred but one has to be careful of the residual distilled water which would be toxic to the endothelim.
Various types of ultrasonic cleaners are available in the market. The basic principle of these cleaners is that the mechanical energy in the form of high intensity, high frequency sound waves is added to the cleaning liquid. The result is a build up and collapse of a large number of minute bubbles throughout the liquid. This effect known as cavitation is responsible for the special scrubbing action which ensures quick and thorough cleaning of all immersed surfaces including holes recesses and otherwise inacessible areas. The instruments should not be thrown together in the ultrasonic bath but should be put separately or placed in separate beakers in order to avoid damage to their cutting edges. The instruments should then be air dried.
A number of techniques of sterilisation are available to us but the one becoming most popular at present is the ETHYLENE OXIDE sterilisation. This machine use Feroxide in a mixture of ethylene oxide and freon in the ratio of 12: 88. It is a low pressure gas, an ideal agent for hospital sterilisation.
The instruments should be packed in 300 gauge polyethylene bags. Each microsurgical instrument should be placed in a small polyethylene bag so that it just about fits the space available. This would prevent contact with other instruments and would avoid unnecessary movement which could spoil the edges. These bags are heat sealed with minimum air in them as this could lead to bursting of the bag during the vacuum cycle. One should use A.T.I. Ethylene oxide indicators in the bags to make sure that adequate amount of gas for the appropriate time has been used and that the bags are sufficiently permeable to cause complete sterilisation. It usually requires 6 hrs of exposure but can vary with the concentration of the gas and the temperature.
Another method of chemical sterilisation is that of using Cidex 2 % which is an activated saturated dialdehyde solution. It kills vegetative bacteria including tubercle bacillus, viruses, fungi and all pathogenic spores. Its active ingredient is Gluteraldehyde. It is non corrosive and can sterilise all kinds of instruments. Instruments are placed on a plastic mat, not touching each other at the bottom of a tray. It requires only 10 minutes for all vegetative bacteria to be killed though total sterilisation including killing of spores takes 3 hrs. after this the instruments are to be rinsed in sterile water.
Dry heat which is bactericidal by causing oxidative destruction of the protoplasm can also be used to sterilise the instruments. A temperature of 150° for one and a half hour is found sufficient to cause complete sterilisation. Any temperature lower than this would result in incomplete sterilisation while any temperature higher than this would spoil the edges. The instruments can be wrapped in brown paper bags and kept in racks in the hot air ovens. The technique of autoclaving i.e. using steam under pressure to kill the organisms is usually inappropriate for metallic instruments.
Microsurgical instruments should be routinely stored in trays with rubber pads and rubber projections in them so that the instruments do not touch each other even accidently as the rubber projection would prevent the sliding of instruments, The tips should be protected by plastic tubing. While keeping the instruments on surgical trolleys, they should be placed on strips of foam or sponges.
To summarise, micro instruments should be handled with extreme care, cleaned immediately after use, packed carefully to avoid damage and should be under the charge of a senior nurse or a doctor. They should be used only for microsurgery and should not be kept with other routine instruments so that, "if you take care of them, they will take care of you" and help you become a competent microsurgeon.
| References|| |
Ming, A.L.S., Ophthalmic Microsurgery, S. karger Basel, Munchen, Paris, London, New York, Sydney, 1980.
Ming, A.L.S., A Color Atlas of Posterior Chamber Implants, PG Publishing, Singapore, Hongkong, New Delhi, 1985.
Stallard, H.B., Eye Surgery, 6th Edition. Ed. Roper Hall, IMLS.,K.M. Varghese Company, Bombay, 1980.