High-pressure injection (HPI) injuries are usually work-related but occasionally involve hobbyists or home repair projects. HPI injuries are rare, even though the use of high-pressure injection apparatus and activities involving the injection of various industrial fluids under high pressure are common industrial processes. These fluids include paints, air, solvents, gasoline, hydraulic fluid, grease, and water. Accidental injection of industrial fluid via an HPI apparatus has serious and often limb-threatening consequences for workers.
Pressure can be as high as 10,000 pounds per square inch (69,000 kilopascals) with velocities up to 400 mph (644 km/hour), which can cause direct and sometimes severe tissue damage. Also, the injected fluid disperses throughout the subcutaneous tissues, often along lines of low resistance, specifically often the neurovascular structures. Many injected fluids are irritating and cause a significant foreign body reaction if allowed to remain in the tissue. Infection rates depend on the substance injected, degree of tissue damage, and the body part involved. Patients should be frequently re-evaluated because the risk for infection following these injuries is high.
Most HPI injuries occur in the nondominant hand of male workers with an average age of 36.
Symptoms and Signs of HPI Injuries
In an HPI injury, the puncture wound is small and not distinct; pain and local swelling is minimal until hours later.
Compartment syndrome Compartment Syndrome Compartment syndrome is increased tissue pressure within a closed fascial space, resulting in tissue ischemia. The earliest symptom is pain out of proportion to the severity of injury. Diagnosis... read more may result from injection of fluid into potential spaces in the extremities and the hands.
Diagnosis of HPI Injuries
Prompt and correct diagnosis is critical to managing high-pressure injection injury. Because the initial symptoms and signs are sometimes mild, these injuries are easily overlooked or minimized, delaying accurate diagnosis and prompt surgical treatment.
Recognition of an HPI injury is apparent by history. The extent of the injury is assessed based on symptoms and examination of all neurologic, vascular, and tendinous structures in the injured body part .
Plain x-rays are taken to check for fractures and, if radiopaque foreign materials are injected, to determine the extent of the injury. Ultrasonography and MRI or CT are sometimes done, but there is no consensus on when they are indicated. Photographs of the injured body part, taken in the acute care setting before surgical exploration, may be useful.
Prognosis for HPI Injuries
The prognosis for patients with HPI injuries depends on the material injected. Paints and solvents cause the most severe injuries and result in the worst prognosis. The force of injection also affects prognosis: Less injury is expected when injection pressure is lower, and more extensive injuries are expected with when pressure is higher.
Amputation rates for HPI injuries are reported to be as high as 50 to 80% if wounds involve solvents. Patients should be warned that permanent local pain, hyperesthesias, hot and cold intolerance, and wound contractures with permanent disability may result from HPI injuries.
Treatment of HPI Injuries
Prompt surgical exploration
In the acute setting, the injured part is gently cleansed, dressed loosely with a sterile dressing, and elevated. Patients are given broad-spectrum IV antibiotics and, if necessary, tetanus prophylaxis Prevention Tetanus is acute poisoning from a neurotoxin produced by Clostridium tetani. Symptoms are intermittent tonic spasms of voluntary muscles. Spasm of the masseters accounts for the name... read more . There is no evidence that the use of corticosteroids improves outcomes, and their use remains controversial.
Clinicians (and patients) should not try to express the injected material out of the entrance wound by applying lateral pressure . Doing so is ineffective and simply spreads the injected fluid farther into the injured tissue. Ice should not be applied to the injured area.
Pearls & Pitfalls
All high-pressure injection injuries require prompt exploration by a knowledgeable surgeon in an operating room; general anesthesia is required. The injured part is widely incised and explored. Dead and devitalized tissue is debrided, and as much foreign material as possible is irrigated and/or sharply debrided from the wound. In most cases, the surgical wound is left open and allowed to heal by secondary intention (ie, without being repaired), or closure is delayed.
Amputation (eg, of digits or limbs) may be required.
Because high-pressure injection injuries may initially cause only minimal pain and swelling, they are easily overlooked, delaying diagnosis and necessary treatment.
Serious consequences, including digit and/or limb amputation, are possible.
Document neurologic, vascular, and tendinous functions, and do appropriate imaging.
Do surgical exploration of all high-pressure injection wounds, with removal of as much foreign material as possible by irrigation and debridement in an operating room.