High-Pressure Injection Injuries

Why this matters

A high-pressure injection injury is the one injury on this shelf most likely to be dismissed by the person who has it, by the coworker standing next to them, and sometimes by a busy triage desk. It looks like a pinprick on a fingertip. It stings, then seems to settle. Over the next hours, the fluid that went in through that pinhole spreads along the tendons and tissue of the hand, and by the time the finger is swollen and white, the damage may already have cost the finger. Hand surgeons treat it as a surgical emergency, and the single biggest factor the person controls is how fast they get to an emergency department and what they say when they get there.

This card follows mainstream emergency and hand-surgery guidance as reflected by OSHA and the American Red Cross. It is not training: hands-on first aid certification is what makes a responder.

The tools that can do it

Any tool that pushes fluid or air through a small opening at high pressure can drive it through skin. Skin can be penetrated at pressures far below what these tools make; figures around 100 psi are commonly cited. The ones a residential shop handles:

Each tool's rated pressure is on its data plate or in its manual. Grease guns, airless sprayers and hydraulic systems commonly run in the thousands of psi, which is why a wound from any of them is never "just a puncture".

Why it looks small and is not

The mechanism is worth understanding, because it explains every first-aid rule below:

• The entry wound is tiny because the stream is narrow. It may be a dot with a little bead of the material.
• The fluid travels. It follows the path of least resistance along tendon sheaths and tissue planes, often well up the finger or into the palm, away from the entry point.
• The material itself does damage. Solvents and paints inflame and kill tissue chemically. Grease and oil cause a slower but serious reaction. Water and air are generally less damaging, but water can carry debris and infection in.
• Pressure builds inside the finger or hand. The swelling compresses blood vessels from inside, so the tissue starves of blood. That is why a finger that was pink at the job can be pale and numb in the ER.

The time course is the dangerous part. Pain is often mild at first and rises over hours as swelling builds. A person who waits to see if it gets worse is waiting through the window when surgery can still prevent the worst outcomes. The surgical literature commonly cites the first six hours as the period in which early surgical cleaning most improves results, and it consistently reports worse outcomes, including amputation, with solvent-based materials such as oil paint and paint thinner.

The first response

Make the tool safe before anyone handles it. Release the trigger, set the sprayer's trigger lock or turn the tool off, and relieve pressure the way the manual describes (the pressure-relief procedure on a sprayer, opening the bleed on a grease gun, isolating and bleeding a hydraulic circuit). A sprayer or a hydraulic line still holding pressure can inject the person who picks it up. Servicing that stored energy afterwards is lockout work under 29 CFR 1910.147 for the mechanical and hydraulic energy involved.

Then, for the injured person:

• Go to an emergency department now. Not urgent care, not the next morning, not after the shift. An urgent care clinic cannot do the surgery and will send them on, losing time. Call 911 if the person is in severe pain, faint or the injury is large, or if nobody can drive them immediately.
• Do not squeeze the wound, do not try to suck or push the material out, and do not cut the skin. All of these spread the material further or add infection.
• Remove rings, watches and bracelets from that hand at once, before swelling makes it impossible.
• Keep the hand still and supported, loosely covered with a clean dressing. Do not wrap it tightly and do not apply a tourniquet.
• Do not apply heat. Cold is not a treatment for this. It does not slow the spread.
• Nothing by mouth. The person may be going to surgery.
• Bring the material's identity. The product container, a photo of the label, or the SDS (safety data sheet). The surgeon's plan depends on what was injected, and "paint" is not enough: oil-based or water-based, and what solvent.

Tetanus. An injection wound is a puncture, and the ED will ask about the last tetanus shot. See related: Puncture Wounds and the Tetanus Question.

What to say at the triage desk

The most important sentence of the whole response is said at the ER door, because a dot on a fingertip can be triaged as a minor cut and left in the waiting room. Some sprayer and hydraulic equipment makers ship a wallet card for exactly this. A shop can make its own and keep one in every van that carries these tools:

  HIGH-PRESSURE INJECTION INJURY
  This is a surgical emergency.
  Please see this patient promptly and
  consult hand surgery.

  Injected material: ______________________
  Base / solvent:    ______________________
  Tool and pressure: ______________________
  Time of injury:    ______________________
  Entry site:        ______________________
  SDS attached:      yes / no

Have the person or whoever drives them say the words "high-pressure injection injury" and hand the card over. That phrase is what tells a triage nurse this is not the cut it looks like.

A worked case: the clogged spray tip

A painter is spraying trim with an airless sprayer and an oil-based enamel thinned with mineral spirits. The tip clogs. He rotates the reversible tip to clear it, but his left index finger is near the tip when the gun fires a burst. He feels a sharp sting and sees a gray dot on the pad of the finger with a smear of paint. It is 10:15.

The scene. His partner sets the trigger lock, turns the sprayer off and runs its pressure-relief procedure before touching the gun or the hose, then sets the gun down on a drop cloth.

The call. The painter says it is fine, wipes the finger, and wants to finish the room. His partner knows the injury: the source is an airless sprayer, the material is a solvent-thinned oil paint, and the injury is a few minutes old. All three point to the emergency department, and the solvent puts this case at the worse end of the outcomes the literature describes. The partner pulls the wedding ring off the injured hand while it still comes off, wraps the finger loosely in gauze, photographs the paint can and the thinner can, and pulls the SDS for both up on his phone.

Getting there. The nearest ER is 20 minutes away and the partner can leave immediately, so he drives rather than waiting for an ambulance, which is defensible because the painter is alert and the injury is localized; with severe pain, faintness or a large injury he would call 911. At the triage desk at about 10:45, half an hour after the injury, the partner says "high-pressure injection injury from an airless paint sprayer, oil-based paint with mineral spirits" and hands over the filled-in card. The painter is taken back promptly and hand surgery is consulted.

What it would have looked like otherwise. The painter's plan was to finish the room and go home. By late afternoon the finger would have been swollen, tight and pale, and he would have arrived well past the period the literature associates with the best results, with a material that is among the worst to have injected.

What changes the answer. If the injection had been a pressure washer stream of clean water into the top of a foot, the material would be less damaging, but the rule would not change: emergency department, the same day, with the source named, because water injection also carries debris and infection and can still need surgery. If the person had been faint, sweating or in severe pain, the partner would have called 911. And if the material were unknown, the photograph of whatever was in the tool's reservoir or line would matter more, not less.

Prevention in one line each

• Never feel for a hydraulic or fuel leak with a hand. Pass a piece of cardboard or wood along the line and look for the wet spot, with eye protection on.
• Relieve pressure before clearing a spray tip, changing a nozzle or disconnecting a hose, following the manual's procedure, and keep the tip guard on.
• Never point a pressure washer wand or a blowgun at a person, and never use compressed air to clean skin or clothes.

References

• OSHA, hazard guidance on high-pressure fluid injection and 29 CFR 1910.147 for controlling stored hydraulic and mechanical energy.
• American Red Cross, current first aid guidance on puncture and injection wounds.
• Hand-surgery and emergency-medicine literature on high-pressure injection injuries and time to surgical debridement.
• See related: The Small Cut From the Grease Gun; Puncture Wounds and the Tetanus Question.
• See related: When to Go to the ER Versus Urgent Care.