Michael Patkin's

On giving injections  

Publication history, Reflections & comments



Surgery & ergonomics


Information design

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The giving of injections for various reasons is an integral part of many fields of medical work. It is all too familiar to the public as a classic television situation, where the doctor figure is about to snatch yet another imperilled victim from the jaws of death, or the villain is immobilizing the hero for his wicked purposes.

One can imagine the director of a drama already licking his lips (yet another stereotype of drama) at the prospect of half a dozen enthralling scenes in the episode being taped. Lying prone is one of the heroes, eyes nearly closed, and tossing (restlessly, of course) from one side to the other. Two or three of his best friends stand on one side, worry furrowed into their brows, or weepy and shielding their eyes from the dread spectacle. On the other side of the patient is our medical hero, eyes narrowed in concentration, expelling the very last minim of air from the upheld syringe before. lie plunges it into the recumbent form.

A quick close-up to the face of the stricken one shows a sudden tensing of the muscles of the face, neck, shoulders and chest as the needle pierces his flesh. Then the mouth opens a little, dramatically, as the audience and the victim's animation are both in momentary suspense. A slow expiration followed shortly by signs of revival are mirrored in a conventional gamut of responses of. the other participants in the drama.

Like the rapid recovery of television characters from knock-out blows, this ridiculous portrayal may leave an unfortunate impression on many people unaccustomed to visiting the doctor's surgery, casualty ward or mass immunization clinic. The results, like those of an older folk-lore, are unwelcome, when hairy-chested soldiers collapse, minutes before their impending imagined ordeal, or children shame their parents by an hysterical display of struggling and screaming.

Today the facts should be different. A disposable 26-gauge needle should not. be perceptible as it pierces the skin, provided puncture is carried out as a quick movement to correct depth, without pulling the skin one way or another by the needle shaft's passage deviating from a straight line. The liquid injected may cause pain from its chemical nature, or from a localized distension of tissue which takes place too quickly for dispersion, and which tears strands of connective tissue or muscle.

Speed in the act of penetration is essential to minimize the time during which the quick component of pain would be felt, and to minimize also by inertia, the tiny funnel of skin pulled in about the shaft of the needle if the metal surface is not perfectly polished so that drat; occurs. This funnelling effect may be seen when an older non-disposable needle, especially if it is blunt, is passed into taughtened skin for a venepuncture, or when the abrupt shoulders of a plastic cannula are pushed through without a preliminary nick. Fortunately with modern needles the smooth polished shaft seems to slide painlessly through the tiny cut made by the point and sharp edges of the bevel.

Psychological conditioning is important. Even the lightest touch of an instrument on normal skin, in a situation where a tense patient expects pain, may give rise to a pain response from the patient. The doctor must hope that lie has inspired reasonable confidence, or that he has a patient with a matter-of-fact attitude. Quite the opposite results from community folk-lore and television programmes with their portrayal of pain.
Distracting the nervous patient old enough to talk is a useful trick. ("Stand on one leg, look right, stand on the other leg, look left, count the pens on the -plip- table.") The worst handicap is the presence of other screaming children, with fear or pain, real or imaginary.

Giving an injection without clumsiness is a motor skill, based or taught on reasoned principles, as with many other types of manual activity. It is difficult to judge the exact amount of speed or force. needed to achieve needle penetration to a given depth. If the. syringe is held like a. dart, the ulnar edge of the hand and little finger can act as a pre-set stop, like a collar on a drill piece which prevents too deep a bole being drilled in wood. With too little force, the skin is not penetrated at that attempt. With too much unguarded force, there is a thud against bone, or the hub hits the skin.

The part to be injected must be held securely if an embarrassing miss is not to occur in the, case of infants, or others likely to make a sudden unexpected movement. A baby's arm or leg can be secured very adequately by placing the index finger above and the thumb below the target area, and the other three, fingers behind the limb, as in a double grip of, the hand for stretching a short segment of string or of sticking plaster prior to cutting it.

A complete list of the elements of work in the mundane task of giving an injection would be formidable. It might include printing on the ampoule which is easily legible even with improperly directed light, and other factors to ensure correct identification. It should include the ease with which the needle is tightened on the nozzle of the syringe. A finely milled round needle hub is more difficult to twist. securely into place than one with coarse ridging which is easier to grip. With the former, the embarrassing accident of the injection spraying back on to the doctor or nurse is much more likely.

Friction between the plunger and the barrel should not be so great that the injector wobbles with the effort of expelling the contents of the syringe so that his coordination is impaired. Despite the many virtues of plastic syringes, they take more physical force to use than good quality ones made out of glass. With some brands, the effort becomes prohibitive.. Measurements with a kitchen scale show that a satisfactory batch of syringes require a. force of 200 gm to move the piston in the barrel, while a brand of much poorer design takes a force of 1600 gm. The latter ones also have sharp edges and little projections due to a poor mould, which stick uncomfortably into the fingertips and make manipulation even more difficult.

The art of cannulating barely visible veins in a fat forearm (some know it and some don't) has enough additional problems to make. it a topic for another occasion. One could add other comment on the delightful design of pudendal block needle guides which are also useful for operative splanchnic block, the stiffness and badly designed finger-rings of ear syringes, the importance, of hand steadiness and good lighting, and the anatomical and clinical features of injections in special sites. However, the likely demand for influenza injections before the. coming winter makes a few points worth noting for those running an immunization clinic for their patients, especially if it is for the first time.

As noted earlier, doctors should look at the quality of the plastic syringes they intend to order so that they do not have a brand which is too stiff to work with. About four-fifths of the time for giving an injection is taken up by loading the syringe, quite apart from recording the event in writing. Loading of syringes should therefore begin a calculated period beforehand, or each injector should have three or four assistants, as well as one to put a dab of antiseptic on the site. This eliminates delay from neglect of the patient to remove his coat or roll up the sleeve, comparable to the preparatory element of motion or therblig, termed "pre-position" by the work study expert. A flow line which allows separate exit, especially for tearful children, will save ragged nerves. Such preparations will obviate, having a resigned or resentful queue of people waiting an hour or two for a five-second procedure. There is more than one way of getting under the skin of a patient.