History and Physical Examination
In cases of high-pressure injection (HPI) injury, a complete history should be obtained that includes the mechanism of injury, the nature of the materials injected, the timeline, and, if possible, the pressure of the machine at the time of injury. [33] Following a physical examination of the involved upper extremity that notes circulation in the digit and evaluates for compartment syndrome, further investigations, such as radiographs, may be helpful (see Workup).
Most frequently, the site of injury is a small puncture wound on the terminal segment of the index finger of the nondominant hand. The average patient is in their second decade of life. [13] The left hand is twice as likely to be damaged as the right hand. [18, 7, 34] A common explanation for this pattern is that inexperienced workers sometimes clean the end of a pressure gun with the tip of a finger. The injection can be painless, and the individual may continue to work [5, 33] ; however, these substances may be absorbed systemically and, within hours of injury, may result in fever, leukocytosis, and lymphadenitis. [16, 35]
The entrance site of an HPI injury is often deceptively small. The injected material acts as a projectile. The physician must look for possible exit sites as well. [12] This seemingly benign appearance may lead some clinicians to send the patient home with analgesia and reassurance. [36] Invariably, the patient returns to the hospital experiencing excruciating pain and unable to move the involved finger or hand. [37]
Depending on the volume and materials injected, the finger may be distended, swollen, and tender on palpation. If vessels in the involved digit have been thrombosed or compressed, the digit may be pale, anesthetic, or even ischemic. [13] In the case of an air-injection injury, associated crepitus and subcutaneous emphysema are possible. [11] Interestingly, Temple et al reported a case of pneumomediastinum after an injection injury to the hand. [38]
The severity of the injury is dependent on many factors, including the following [7, 39] :
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Type, toxicity, temperature, amount, and viscosity of the material injected
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Pressure of injection
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Involvement of synovial sheaths
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Anatomy and distensibility of the injection site
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Secondary infection
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Time interval between injury and surgery
With paint and other solvents, factors affecting dispersion of the material include the pressure of injection, the elasticity of tissue, and the viscosity of the substance itself. [35, 40] In addition, the site of penetration can influence the extent of injury. [39]
Kaufman performed experiments on cadaver hands in which he injected wax at 750 psi. [41] By varying the site of injection, he discovered that injection over the fibrous tendon sheath resulted in the injected materials collecting in the tissues around the sheath, rather than within the sheath itself. When the membranous portion of the sheath was involved, the result was filling of the sheath with the injected material.
The former situation resulted in extensive neurovascular damage, with spread of the substance through loose subcutaneous tissues and into fascial planes; the latter situation caused the injected material to travel long distances. [41] In some cases, the proximal elbow may be reached along the flexor tendon sheath. Injected material may also travel into the deep spaces of the hand. [17]
Infection following HPI injuries is seen more commonly in digits that have not been treated. Ischemia and necrotic tissue are a haven for the proliferation of microbes. Coincidentally, many materials injected have antimicrobial properties. [18, 11] Amputation rates for HPI injuries range from 16% to 55%. [18, 7, 13, 39, 42]
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Photograph taken approximately 12 hours after high-pressure injection injury involving paint.
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Photograph taken after urgent debridement following high-pressure injection injury involving paint.
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Photograph taken 48 hours after high-pressure injection injury involving paint.
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Debridement of necrotic index and middle digits following treatment of high-pressure injection injury involving paint.
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Reconstruction of high-pressure injection injury with abdominal flap.
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Excellent functional recovery after reconstruction of high-pressure injection injury with abdominal flap.
