12.1 Compression Types, Indications, and Contraindications

Why compression is the venous intervention

A venous leg ulcer (VLU) in the gaiter region is a pressure problem. Ambulatory venous hypertension drives edema, inflammation, and a wound that weeps through every dressing you name. Independent OpenExamPrep teaching for Certified Wound Care Nurse (CWCN) candidates treats therapeutic compression as the mechanical therapy that actually lowers venous hypertension, not as an accessory after a foam is chosen. You still cleanse, debride when indicated, and manage exudate. You do not pretend a dressing brand replaces a 30–40 mmHg ankle dose.

The exam asks you to pick a class of wrap and to know when the class is unsafe. A Profore-type kit, a CircAid-type Velcro garment, or an Unna paste boot is an example of a class, not a product you are required to promote.

Laplace’s law, conceptually

Laplace’s law, used conceptually in bandaging, says sub-bandage pressure rises with tension and with the number of layers, and falls as limb radius (circumference) and bandage width increase. Pull harder, pressure rises. Overlap so two layers sit where one sat, pressure rises. Wrap a thin ankle (small radius) with the same pull you used on a large calf, pressure is higher at the ankle. Let a wrap slip into a narrow cord, effective width collapses and focal pressure spikes like a tourniquet.

That geometry is why a correctly applied wrap is graduated even before you “think gradient”: the ankle is narrower than the calf, so even tension yields higher pressure at the ankle. It is also why padding over the malleoli, tibial crest, and Achilles is not cosmetic. Padding increases local radius over bone and drops the focal pressure that would otherwise necrose a prominence.

Laplace is not a license to yank. Tension is one variable. A high-resting elastic wrap on a skinny ankle can overshoot the therapeutic window. A loose wrap on a large, wet leg can deliver almost no working pressure no matter how confident the spiral looks.

Therapeutic high compression

For a typical VLU with adequate arterial inflow, the usual target is about 30–40 mmHg at the ankle, with lower pressure as the system climbs the calf. “Adequate” means a current ankle-brachial index (ABI) generally above about 0.8, no ischemic rest pain, and viable tissue—not a guess from warm toes in a warm clinic. High compression on a limb that cannot deliver arterial blood is how a venous-looking ulcer becomes necrotic.

Short-stretch versus long-stretch

Short-stretch (inelastic) bandages elongate little. When the calf muscle pump fires against a relatively rigid cylinder, working pressure is high and edema is driven proximally. At rest the cylinder does not squeeze as hard, so resting pressure is lower. That profile suits people who walk and is often better tolerated recumbent than a high-resting elastic system.

Long-stretch / elastic bandages (the classic Ace-type wrap) recoil strongly. They maintain higher resting pressure. They do not give the same rigid counterforce to the calf pump. They are easy to apply too tightly, stay tight when the person is in bed, and are a trap when someone treats “any tight wrap” as therapeutic venous compression.

Multilayer, Unna, inelastic wraps, and stockings

A Profore-type four-layer kit is a class example. Typical order is orthopedic wool or padding, a light crepe to anchor, a light elastic compression layer, and a cohesive outer layer that maintains the system. When ankle circumference is in the kit’s intended range—commonly about 18–25 cm for a standard kit—the assembled system is designed to deliver roughly 40 mmHg at the ankle and about 17 mmHg at the knee. Wrong-size ankles need the matching kit or a different class. Stretching a too-small kit is an unmeasured dose, not resourcefulness. Change often weekly if exudate is managed; sooner if the wrap slips or soaks through.

An Unna boot is zinc oxide paste gauze that dries into an inelastic cylinder. Working pressure depends on walking. Many clinicians add a cohesive outer wrap (sometimes called a Duke boot) to hold the paste. Typical change interval is about weekly. The person cannot bathe the wrap. Zinc or adhesive allergy is a stop. Unna systems underperform in people who do not ambulate, because there is little working pressure without a calf pump.

CircAid-type inelastic adjustable wraps (Velcro inelastic garments) let the person or caregiver tighten as edema falls. They are useful for self-management and fluctuating volume. Teach not to crank straps into a tourniquet, and to leave toes visible for color checks.

Once the ulcer is closed, graduated stockings maintain the gain. 20–30 mmHg is a common moderate class for milder edema, intolerance of a higher class, or some mixed disease when vascular agrees. 30–40 mmHg is the usual maintenance class after VLU healing if arterial status allows. Stockings that live in a drawer do not count as compression.

Indications versus stop rules

Indications for therapeutic compression include VLU with adequate arterial inflow, venous edema that feeds the wound, and maintenance stockings after healing. Match the class to mobility: short-stretch and Unna-type inelastic systems need a calf pump to generate working pressure; elastic multilayer kits still require a competent wrap and a limb that can tolerate resting pressure.

Uncompensated congestive heart failure (CHF) is at least a relative caution. Compression moves edema into the central circulation. Bilateral high wraps move more volume than a single leg. If the person already has pulmonary edema, orthopnea, or an acute decompensated picture, hold compression until the heart failure is treated. A euvolemic, compensated person with a VLU may still receive compression with monitoring—that is not the same as wrapping someone who is drowning in their own lungs.

Untreated acute deep vein thrombosis (DVT) is not a clinic wrap-and-see. A hot, swollen, unevaluated leg needs vascular or medicine evaluation. After anticoagulation is in place, those teams often endorse compression for symptoms; that is their sequence, not a CWCN solo decision on an untreated clot.

Untreated infection or cellulitis is controlled first. Spreading, febrile cellulitis is not an indication to bury the limb in four layers. Once source control and antibiotics are underway and the person is improving, compression often helps by reducing the edema that impairs host defense.

Clinical scenario

A 71-year-old has a medial gaiter ulcer, hemosiderin, and pitting edema. Pulses are palpable, there is no rest pain, and ABI today is 0.92. A colleague applies a single long-stretch Ace from mid-calf downward “to tighten the calf” and leaves the foot out. Independent OpenExamPrep teaching flags the miss: the ankle never received a 30–40 mmHg therapeutic dose, the wrap is high-resting elastic rather than a venous class system, and the gradient is reversed. A short-stretch or multilayer class wrap, distal to proximal, with padding at the malleoli, matches the indication. If the same person later presents with crackles and a five-pound overnight gain, you hold the next wrap until volume overload is treated—even though yesterday’s ABI still looks reassuring.