On Vietnam’s battlefields, doctors were faced with massive numbers of casualties -many with horrifyingly severe internal wounds and in imminent danger of bleeding to death. The task of the surgeon was to treat each casualty effectively but quickly in order to move on to the next patient. A new kind of wound dressing was needed to speed up the surgical procedures accordingly. Tissue adhesive or surgical glue, applied by spraying, proved highly valuable in dealing with serious hemorrhaging under pressure of time.
The idea of a quick-acting tissue adhesive has been a surgeon’s dream for many years. For instance, when operating to repair the liver of a soldier wounded by shrapnel, massive bleeding must be brought under control within minutes—but, the delicate tissue of the liver requires painstaking stitching that demands hours of concentrated work. A quicker answer lies in a spray can.
Ideally, the surgeon would be able to spray the bleeding regions with a fine transparent film, which bonds immediately with the tissue, creating a complete seal and staunching the flow of blood. Then the surgeon could hold together the edges of the cut tissue and rejoin them with a swift spray from the same can. when the patient wakes up and surveys his stomach, all he would see is a thin line marking the length of the first incision: no stitches no clips, no staples.
Sadly, this ideal procedure is not yet a reality. The enticing idea that wounds — from superficial grazes to internal hemorrhages — might be safely sealed by the simple application of an appropriate glue has attracted the research departments of several major drug companies for at least 20 years. The fruits of that research have been marketed and they show great promise in a number of specialized applications. A satisfactory product for general surgery is still, however, only dream.
Surgical glues so far developed are based around a family of compounds known as cyanoacrylates. These are organic compounds that are compatible with the biochemistry of living systems, and that are more or less nontoxic to living cells. In the presence of moisture, these compounds undergo a rapid reaction as strong chemical bonds are formed between individual cyanoacrylate molecules. This reaction — called polymerization —changes the compound from a liquid into a semisolid gel with considerable strength. Extra bonds are also formed between individual cyanoacrylate molecules and the surrounding tissue. The result is a tough lattice of molecular chains firmly fixed at the site of application.
One of the most severe problems with tissue adhesives is an inflammation of the wound caused by a slightly toxic reaction to the glue. Following the original injury, this irritation increases the chances of post-operative infection at the site of the wound. Both local healing and overall recovery are often slowed. Furthermore, the medical teams using surgical glue in Vietnam found evidence that even noninflamed wounds sealed with the adhesive did not heal as fast as those closed with conventional stitches. Possibly, this retardation of the healing process may be due to the adhesive film slowing the penetration of new cells across the gap and preventing microscopic blood capillaries from growing back into the wounded region.
Since Vietnam, research into surgical glue has discovered one solution to both these problems: use less adhesive. A recurring problem with the battlefield trials will be familiar to anyone who has ever used spray paint. The spray nozzles kept getting blocked. To avoid this, the spray cans used in Vietnam tended to have large holes – but this meant that it was difficult for the surgeons to apply the adhesive in minimum amounts. Today, special aerosol designs can eliminate the problem of blocking and so it is possible to apply the adhesive in very thin layers. Transparent flexible shields are also used to confine the spray to just the areas required.