Ouch: crushed fingers and purply-black nails

1 October 2014

Fingers may be small but wounds to them can be disproportionately painful and debilitating. FIONA CASSIE seeks first aid advice for nurses from emergency NP Margaret Colligan on crushed fingers and other common finger wounds.

Black finger nailIt happens all the time. A hammer heading for the nail hits the thumbnail instead. Or a lapse of attention sees fingers jammed in a door, drawer, or machinery.

The wounds may be small but the pain of a throbbing swollen finger or fingers is not easily forgotten.

“Mostly the (crushed finger) injuries that present at ED are people who may have been chatting to someone with their hand on the open car door and then they have inadvertently closed the door,” says Auckland Hospital ED nurse practitioner Margaret Colligan.

She says the pain that brings people into ED is usually caused by bleeding under the nail (subungual haematoma) following a minor laceration.

“The blood that forms under the nail has nowhere to go because it is such a small compressed area and that is why it throbs so much.”

When a nurse in a general practice, rest home, or other community setting has a patient present with a throbbing finger and a subungual haematoma, they need to follow initial first aid steps (see sidebar). They then need to assess whether they can care for the wound or if the damage is such that the person needs to be sent to ED.

Colligan says in the case of industrial accidents, the blow to the finger can have significant force behind it and often the worker may have also broken the bone underneath the nail and suffered significant damage to the nail.

In cases where the patient has a very sore and swollen finger or fingers and there is a suspected fracture of the bone and/or the nail is badly crushed or cracked, the person needs to be referred to ED or an A&E clinic as the nail is likely to have to be removed and the nail bed repaired. An X-ray will also be required.

If the nail is intact and bone fracture unlikely, the nail can be assessed by the nurse for trephination (i.e. making a hole in the nail to release the blood and so reduce the pressure and pain).

Colligan says one factor nurses have to take into account before trephination is how recent the injury is. After 12–24 hours, the blood under the nail is likely to be clotted and trephining will have less impact.

If the haematoma covers 50 per cent or more of the nail, trephination is likely to be worthwhile in relieving pain. If the coverage is 25 per cent or less, a judgment call needs to be made on whether trephination will benefit the person.

Before trephination the nail must be cleaned. The best way to actually carry out trephination is a matter of some discussion (see sidebar).

Colligan says her preferred method is to use a sterile 18-gauge needle and gently rotate the needle (between finger and thumb) down through the nail until it pierces the nail and blood comes out.

If there is a fracture underneath the nail, there is conflicting evidence about whether prophylactic antibiotics should be used after trephination because there is a portal through the nail for infection into the tissue.

“I can’t find any good evidence to support that (prophylactic antibiotics), but anecdotally, that seems to be the practice,” says Colligan.

“This is particularly the case if the injured person is, for example, a mechanic in a garage who is going to continually get the finger dirty. I would have a higher threshold for giving them antibiotics then somebody who works in an office environment.”

Colligan says nails usually grow back within three to six months without any complications.

FIRST AID RESPONSE TO CRUSHED FINGERS

  • Run injured fingers under cold water for 10-20 minutes OR apply ice wrapped in facecloth or gauze on injured area to stop further bleeding.
  • Offer simple pain relief.
  • Check history of injury – including level of force causing the injury.
  • Assess whether nail badly damaged - or that the level of pain, swelling and inability to move finger indicates a possible broken bone and if so refer to ED or A&E clinic.
  • If crush injury is elsewhere on the fingers and is accompanied with major swelling and loss of movement – even if the skin is not broken – a tendon may be lacerated and the injury should be reviewed in ED or A& E clinic. Or if delayed presentation and there is a risk the injury is now infected.
  • If nail intact and fracture unlikely, assess any bleeding under nail – and the patient’s level of pain - and decide whether trephination will be helpful in reducing the pressure and pain.
  • Clean nail area and use appropriate trephination technique (see trephination sidebar) endeavouring not to damage the nail bed.
  • Always consider giving a tetanus booster – particularly if injury happened in garden, or other contaminated areas
  • Consider prophylactic antibiotics after trephination - depending on level of damage to nail, occupation and likelihood of contamination of the wound 
  • Be cautious with patients who are immuno-suppressed or slower healing because of underlying disease like diabetes or vascular disease – a key thing is to keep injury elevated to help circulation.
  • Elevate injury in sling for 12 to 24 hours to help reduce swelling and also help with reducing pain.
  • Follow-up: if patient can’t move fingers, or throbbing pain persists beyond 24 hours, then refer on.

TREPHINING TECHNIQUES  - a matter of some debate 

The methods of trephination are not without controversy.

The ACC’s 2008 Nursing Treatment Profiles came out against the technique of using straightened-out paper clips heated on a flame until hot enough to burn a hole through the nail and release the blood.

The ACC note says while using a hot paper clip was a “simple, common and straightforward” procedure the practice remained “somewhat primitive” and has hazards related to it being performed incorrectly. Including the risk of introducing “lampblack” (carbon filament foreign bodies) into the wound.

ACC also advised strongly against using a sterile needle. “Super-heated needles will certainly puncture the nail but the over-exuberance of the practitioner can cause unnecessary trauma to the nail bed from too much pressure and the super-sharp needle point,” says the guide.

The 2008 publication advises instead that using disposable electrocautery devices is considered “more current and humane”.

But subungual haematoma advice, updated in September 2014, on the American Medscape website still includes using a heated paper clip or an 18 gauge needle as options for trephination along with a cautery tool. Though it does add the caution that injury to the nail bed can result if the nail penetration tool used is advanced too deep.

The web article includes a video demonstrating the needle technique: http://emedicine.medscape.com/article/82926-overview#a15

Some other articles also refer to a haematoma trephination technique* using an extra-fine 29 gauge insulin syringe needle. And instead of penetrating the nail, inserting the needle under the nail (via the quick i.e. hyponychium) and keeping the needle parallel to the nail and as close as possible to the nail to avoid injuring the nail bed.

* Kaya et al, Extra-Fine Insulin Syringe Needle: An Excellent Instrument for the Evacuation of Subungual Hematoma. Dermatol Surg. Nov 2003;29(11):1141-3.

SPLINTERS or THORNS

  • If patient arrives with a swollen, painful finger and there is suspicion of a foreign object in their finger or hand they should be referred to ED
  • Organic materials like rose thorns or phoenix palm can cause very bad infections.
  • Only attempt to pull out splinter or thorn if you can confidently and easily remove all of it and then give the wound an extensive clean
  • Check whether patient needs tetanus booster
  • If not confident that all of the splinter or thorn is out then send them into ED
  • An infection in tender sheaf of finger can transfer quickly up the hand and into the forearm. So have very low threshold for getting such injuries reviewed
  • No point x-raying for organic material like thorns or wood splinter – need an ultrasound