Instruments I: Families and How They Work

This is Unit Twelve of Tech in Surgery Prep. Unit Eleven ended with a room checked and ready. This unit opens the instrument tray, the scrub person's own territory. Carry one idea through this lecture. Instruments are easiest to learn by function, because almost every basic instrument belongs to a small number of families. Names come later; knowing what an instrument does tells you when the surgeon will want it. Every instrument fact in this unit rests on two independent references. A worked example near the end shows a new scrub person naming a tray this way. By the end you will be able to sort instruments by family and explain how a ringed instrument works. To identify the blades and scissors. To identify forceps, hemostats and tissue clamps. And to choose needle holders and tell look-alikes apart.

Four entries on the instrument families, and on the parts that make a ring-handled instrument work.

Learning by function.

TSC 276 Instruments by Function

Instruments are easiest to learn by function, because almost every basic one belongs to a few families: cutting and dissecting, grasping and holding, clamping, retracting and exposing, suturing and stapling, and suctioning. Names come later; knowing what an instrument does tells you when the surgeon will want it.

From the rings to the tips.

TSC 277 How a Ringed Instrument Works

Many instruments are ring-handled. The thumb and finger go through the rings. Clamps and needle holders have a ratchet near the rings that locks the jaws in steps, so the grip holds without squeezing. The two halves pivot at the hinge. The jaws or blades may be serrated, toothed or smooth, and the tips straight, curved or angled. Scissors share the rings and hinge but have no ratchet. Blood collects at the hinge and jaws, so these instruments are opened for processing, and a stiff hinge is reported, never forced.

With a ratchet, or without.

TSC 278 Locking and Non-Locking Instruments

Grasping instruments either lock with a ratchet or do not. Clamps are locking instruments that hold tissue or vessels; thumb forceps, called pick-ups, are non-locking and held closed by hand. A clamp left on tissue stays closed by itself, so every clamp on the field is tracked.

How the jaws meet tissue.

TSC 279 Serrations, Teeth and Jaws

A grasping instrument's surface decides how it treats tissue. Serrations add friction without piercing; teeth hold tough tissue firmly but can damage delicate tissue, so instruments are called traumatic or atraumatic. Teeth and serrations are different features, and the wrong one can tear tissue.

Five entries on the cutting family: knife handles, blades, and the scissors seen most often.

Asked for by number.

TSC 280 Knife Handles and Blades

Surgeons usually ask for a scalpel by its blade number. The number ten is large and curved, for long skin incisions. The number eleven has a pointed tip, for precise stab incisions. The number fifteen is smaller and curved, for short, fine incisions. A number three handle commonly carries the ten and also takes the eleven and fifteen, and a long version reaches deeper; the thinner number seven handle suits deep, narrow spaces. Sets often include a skin knife and a second, clean knife for deeper work. A request for an eleven usually means a stab incision is coming.

A blade is a sharp.

TSC 281 Blades Are Sharps

Scalpel blades are sharps: counted, passed with care, and disposed of in a sharps container. Safety-engineered options include shielded or retracting scalpels. A blade is never left loose on the field or in the tray after the case.

Heavy scissors and fine ones.

TSC 282 Scissors: Mayo and Metzenbaum

The two scissors seen most are Mayo and Metzenbaum. Mayo scissors are heavy and strong with short blades; curved Mayos cut tough tissue such as fascia and muscle, and straight Mayos cut suture and other non-tissue items. Metzenbaum scissors, called Metz, have long, slender shanks and fine tips for cutting and dissecting delicate tissue and spreading planes. On a tray, tell them apart by proportion. Metz are kept for delicate tissue, so suture and heavy material go to the Mayos.

The suture scissors.

TSC 283 Straight Mayo for Suture

Straight Mayo scissors cut suture, which is why they are sometimes called suture scissors. They also cut other non-tissue items such as mesh, drains and dressings, sparing the finer scissors. Expect to pass them each time a tie or stitch needs cutting.

Scissors for delicate work.

TSC 284 Fine Scissors

Fine scissors include iris scissors, with very sharp fine tips for fine dissection and fine suture, and Potts scissors, with angled blades for opening and extending incisions in blood vessels. Their tips are fragile, so they are protected on the field and in processing.

Ten entries on grasping and clamping: thumb forceps, hemostats, and the tissue clamps, each matched to the tissue it holds.

Pick-ups, by what they hold.

TSC 285 Thumb Forceps

Thumb forceps are non-locking instruments for grasping tissue or objects. DeBakey forceps are non-toothed and atraumatic, for tissue including bowel. Adson forceps are small with fine tips, and the toothed version holds skin edges for closure. Heavy toothed forceps, such as Bonney forceps, hold tough tissue like fascia. Russian forceps have rounded serrated tips for dense tissue. Non-toothed dressing forceps handle dressings and packing. Toothed forceps on bowel can puncture it, so atraumatic forceps stay ready whenever bowel is handled.

Teeth for tough tissue.

TSC 286 Toothed or Smooth

Toothed forceps grip tough tissue such as skin and fascia; smooth, atraumatic forceps handle bowel and other delicate structures. Toothed forceps are never used to hold a suture needle, because the needle damages the teeth.

Two small forceps alike.

TSC 287 Adson and Its Relatives

Adson forceps are small, fine-tipped thumb forceps for delicate or superficial tissue such as skin edges. The standard toothed Adson has one tooth fitting between two; the Adson-Brown has rows of very fine teeth. They look alike from a distance, so ask which one the surgeon wants.

Clamping a bleeding vessel.

TSC 288 Hemostatic Clamps

Hemostatic clamps, called hemostats or artery forceps, clamp vessels so they can be tied or sealed. The surgeon grasps a bleeder with the serrated jaws, the ratchet locks the clamp so it holds alone, the vessel is tied or sealed with electrosurgery, and the clamp is released and returned. They come straight or curved and in many sizes, and curved ones can spread tissue in blunt dissection. In heavy bleeding, several may go on in quick succession, so have more ready and track where each goes.

Two common hemostats.

TSC 289 Crile and Kelly

Crile and Kelly clamps are hemostats with similar uses and looks. The Crile is a standard non-toothed hemostat, often called a snap; the Kelly is a larger variation that secures bleeders before they are tied or sealed. Sets keep them in labelled order, and the surgeon's request decides which is passed.

Sized to the vessel.

TSC 290 Mosquito and Large Clamps

Hemostats are sized to the vessel. The mosquito is the smallest common one, for small bleeders in delicate surgery; larger clamps, such as the Kelly, handle larger vessels and tissue. Too small a clamp on a large vessel risks slipping.

Reaching behind a vessel.

TSC 291 Right Angle Clamps

A right angle clamp has jaws bent at a right angle, to reach around and behind vessels and ducts. Surgeons dissect around a structure with it and pass a tie or vessel loop underneath to tie it off or lift it. When a right angle is asked for, have a tie ready next.

Clamps that hold tissue.

TSC 292 Tissue Clamps: Allis, Babcock, Kocher

Tissue clamps hold tissue rather than vessels. The Allis has short interlocking teeth that grasp firm tissue such as fascia, is often used on tissue being removed, and some use it to hold bowel during a resection. The Babcock has smooth, rounded, open jaws that encircle tubular structures, such as intestine, without crushing them. The Kocher has teeth at its tip and holds tough, slippery tissue such as fascia. The Allis is not gentle, so for bowel that will stay in the patient, the atraumatic Babcock is usually right.

Telling two apart.

TSC 293 Allis and Babcock Side by Side

The Allis and the Babcock look alike from a distance, and the difference is at the jaws. The Allis has sharp interlocking teeth; the Babcock has a smooth, rounded window with no teeth. Glance at the jaws, not the handles, before passing either.

Holding the drapes.

TSC 294 Towel Clamps

Towel clamps are ratcheted clamps that hold towels and drapes around the field. Penetrating ones have sharp points and can also grasp tough tissue being removed. They are not used to attach cords or tubing to drapes, because they puncture drapes and can damage cables.

Three entries on needle holders and sponge forceps, then two worked examples. The opening idea is paid off at the first.

Gripping the needle.

TSC 295 Needle Holders

A needle holder, or needle driver, is a ratcheted instrument that grips a suture needle firmly through tissue. The Mayo-Hegar is the general-purpose type for medium and heavy needles, such as for fascia. Smaller ones, such as the Webster, hold fine needles; very fine spring-handled ones, such as the Castroviejo, serve eye and microsurgery. Length follows the depth of the wound. The needle is gripped at a right angle, about a third of the way back from where the suture attaches. Too large a holder can bend a needle, so match and load it before it is asked for.

Needle and wound together.

TSC 296 Sizing the Needle Holder to the Needle

The needle holder is matched to both the needle's size and the wound's depth. Fine needles need small, fine-jawed holders; heavy needles need sturdy ones; deep wounds need longer instruments. A loose grip lets the needle rotate, and an oversized holder can deform it.

A sponge on a stick.

TSC 297 Sponge Forceps

Sponge forceps are ring-handled clamps that hold a folded gauze sponge as a sponge stick. Sponge sticks are used for skin preparation, blotting blood and gentle blunt dissection deep in a wound. A sponge on a stick is still a counted sponge.

Ten instruments, two questions.

TSC 298 Naming Ten Instruments on a Tray

A worked example, constructed for this course, pays off the opening idea. Quinn, a student, stands at a basic tray with a mentor who says: family first, then the name. A curved blade on a handle is cutting: a number ten on a number three handle, for skin. The heavy, short-bladed straight scissors are a straight Mayo, for suture; the long, slender pair is a Metzenbaum. Smooth fine forceps are a DeBakey; a small pair with a tooth pattern is a toothed Adson. A small curved hemostat is a mosquito, a larger one a Kelly. Bent jaws mean a right angle; a smooth rounded window, a Babcock. Short stout jaws with a ratchet: a Mayo-Hegar needle holder. A name with its job helps in a case.

Look-alikes under pressure.

TSC 299 The Look-Alikes on the Mayo Stand

A worked example, constructed for this course, follows Sky on a bowel resection, where several pairs are easy to confuse. A curved Mayo and a Metzenbaum are told apart by proportion: the Mayo for fascia, the Metz for delicate tissue. An Allis and a Babcock look the same at the handles, so Sky looks at the jaws, and passes the Babcock for bowel that will stay. A toothed Adson and an Adson-Brown go on opposite sides of the stand. The loaded needle holder has its own fixed spot, apart from the hemostats, so a hurried grab never produces a clamp. The remedy for look-alikes is a habit: look at the working end, and keep look-alikes apart.

Look at what you can now do. You can sort instruments by family, explain the rings, ratchet, hinge and jaws, and tell locking from non-locking and teeth from serrations. You can name the common blades and handles by number, and choose between Mayo, Metzenbaum and fine scissors. You can match thumb forceps, hemostats and the Allis, Babcock and Kocher to the tissue they hold. And you can size a needle holder to its needle, count a sponge stick, and keep look-alikes apart on the stand. Unit Thirteen continues the tray with retractors, suction and specialty instruments.