High Pressure Water Jetting Injuries
Pressure injection injuries, especially to the hand and upper extremities, with water, grease, paint, gasoline or paint thinner are well described. High pressure injection injuries are serious injuries with life and limb threatening potential. The pressure required to penetrate the surface of the skin is in the order of 7x105 N/m2 or 100psi. However, pressures currently used for ultra high pressure water jetting can exceed 2500bar (35,500lbs/in2). The combination of irritant material and high pressure results in an extremely intensive inflammatory reaction which develops within hours of the injury occurring. The irritant material may travel proximally along visceral planes, nerves or tendon sheaths resulting in vascular compression and local necrosis.
Nature of Injury
The theoretical velocity of the jet can be derived from the formula: 8.3vp (p=lbs/in2). With water pressures up to 2500bar (35,500lbs/in2) velocity in the order of 1,550 m.p.h. (2,500 KM/HR) can be encountered.
The kinetic energy dissipated on impact can, of course, be derived from KE = MV where M is the mass of water ejected and V the velocity of impact. Even with parts of the body that have a capacity to absorb only small quantities of water, say 0.035 oz (1 gramme) as in the case of the finger, the energy expanded may be of the order of 1,500ft lbs (63.21 Joules). With other parts of the body with greater capacity the energy levels will be much higher.
When a high pressure injection injury occurs the kinetic energy absorbed by the tissues is substantial and the toxic material is often driven from the fingertip to the palm. Injuries in which an irritant material is injected have a particularly poor prognosis even with the prompt exploration and debridement. Amputation of the finger is often required in these cases.
Water injection injuries do not result in the same degree of secondary tissue damage and toxicity although the greater pressures and nozzle velocities can result in very extensive tissue injury. The pattern of tissue damage can be similar to that of high velocity missile gunshot wounds. All high pressure water jet injuries should be considered surgical emergencies. The small entrance wound and lack of an exit wound is not indicative of the extensive disruption of deeper tissues which can result from dispersion of kinetic energy penetration of the skin by water.
High pressure water jet injuries may result in the infiltration of water and air into the tissue planes. The resulting subcutaneous emphysema can be an indication of the extensive internal damage. A classic radiographic appearance of diffuse subcutaneous air may be found.
High pressure water jet injuries present with several unique features. The external manifestations in the injury are unreliable in predicting the extent of internal damage. Bacterial or chemical inoculation can cause significant morbidity. High pressure water jet wounds may involve vascular or neurological injuries. Wounds of the abdominal wall may involve intraperioneal injuries.
1. At Scene
The importance of the injury and the potential severity must be recognised immediately.
First aid measures should include controlling any bleeding by the application of pressure over the bleeding site and elevation of the injured limb where possible.
Arrangements should then be made for the immediate transfer of the patient to a hospital medical facility.
It is recommended that the hospital Accident and Emergency Department be contacted by telephone whilst the patient is in transit with the following details:
- Time of the injury.
- The nature of the material in the jet.
- To reiterate to hospital Accident and Emergency staff that although the initial injury may appear to be minor, the potential for serious complications arising exists and these patients require referral to the duty Orthopaedic team for assessment.
2. In Hospital
Assess the patient for any life-threatening injury and ensure that the airway, breathing and circulation are controlled and stable.
Control any external haemorrhage by the application of pressure.
Obtain the following details in the history:
- Time of the incident.
- Details of the contaminant.
- Past medical history.
- Any antibiotic allergies.
- Date of last Tetanus injection.
- General examination.
- Examination of the injury site - note the size and site of the entry wound.
- Check for local swelling.
- Assess the range of movement.
- Assess nerve and tendon function.
- NB. A Normal examination at this stage does not exclude serious and potentially limb threatening complications developing.
4. Obtain x-rays of the injured area to check for presence of subcutaneous air.
5. Refer the patient for assessment by a senior Accident and Emergency doctor or the Orthopaedic team.
6. The patient should be taken to theatre for exploration of the injured limb.
7. Prophylactic broad spectrum antibiotics will be required at the earliest possible stage.
8. Ensure that Tetanus prophylaxis is up to date.
High pressure water jet injuries should be considered surgical emergencies. A high index of suspicion of associated internal injuries and aggressive surgical intervention are required.
Although water injection is not as toxic to petroleum based agents, high pressure water injuries pose a serious risk of bacterial infection (20%). Bacterial contaminants include gram positive and gram negative bacteria, fungi and uncommon pathogens including aeromonas hydrophia. The water used in high pressure jet devices may be contaminated with sewage or oil lubricants. For these reasons, broad spectrum antibiotics should be started and continued for several days post operatively.
Unfortunately, the initial apparently minor nature of the injury associated with the delay in the progression to severe inflammation frequently results in a delay in referal. The management of such injuries consists of immediate exploration, extended as widely as necessary with surgical debridement of all toxic material, areas of obvious necrosis should be excised and the wound left open. Serial surgical debidement may be necessary. Open wound management has been shown to offer the best results for injuries. One series reported an 84% digit salvage rate and return to normal hand function in 64% of patients. Amputation may be necessary in some cases.