High-pressure injury to the hand is caused by accidental injection of wide varieties of materials. These fluids are injected with high pressure ranging from 40 to 800 atm with a velocity as much as 180 m/seconds (
4). The highly pressurized fluid can penetrate the skin through protective gloves without direct contact with the hand ( 5).
Various types of industrial equipment and substances including paint, paint thinner, gasoline, oil, grease and even water, have been reported (a,b). Grease, diesel and paint are the most commonly reported injected substances. This was the same as the results of our study, in which grease was the most common injected material (
Several mechanisms have been reported in the pathophysiology of vast soft tissue injury. The kinetic energy of the injected material can result in immediate soft tissue necrosis. Edema, vascular spasm, chemical irritation, necrotizing inflammatory reaction due to cytolytic properties of these materials and finally infection are the involved factors in developing severe damage to the vital and delicate soft tissue of the hand (
The non-dominant hand and index finger are at a higher risk to be injured (
2, 6, 7). This was true with our patients, where the index finger of the non-dominant hand was involved most of the time.
Prognosis of the injury is under influence of multiple factors. Nature of the injected material is the most important item. Paint and chemical solvents are more irritating than water, and water based materials or greases. The injection pressure is the prognostic factor. Higher pressure results in more intense and severe damage and necrosis (
6, 7). Volume of the injected material and also the site of injection are important in dictating the prognosis. Finally time delay of the incident and the treatment is a determinant factor ( 6, 7).
After high-pressure injection, the presenting sign and symptoms are usually minimal. Pain and swelling at the initial presentation are not significant. The entrance of the foreign materials is a small pinprick and this can lead both the patient and heath care personnel to underestimating the injury, which in turn results in a delay in the initiation of the classic treatment and urgent decompression. Eventually, the injured part becomes swollen and painful. In a few hours it will edematous, pale, cold and the chance for irreversible damage and amputation will increase.
The amputation risk is about 16 - 55%. It will be as high as 50 - 80% when the injected material is a solvent (
8). Time delay of treatment initiation is also a prognostic factor for amputation risk. Stark et al. reported that, treatment during the first 10 hours after injury results in better outcome ( 9). Another study reported that they did amputation for patients, who were admitted after a 72-hour delay ( 7).
Mean time delay to first treatment procedure for our patients was 29.16 ± 25.66 hours for seven patients and none of them had amputation. The only case of amputation was for case No. 8, who had referred to our center after seven days of delay without any treatment for the injection injury. This low rate of amputation in our patients may be partly due to the nature of the injected materials, which were grease most of the time. The other possible factor is the initiation of primary urgent surgical decompression and debridement as soon as possible after admission to the hand surgery department.
Treatment of the injury needs a classic approach. The patient should be admitted to the hospital and broad-spectrum antibiotics should be administered. The role of the corticosteroids in prevention of amputation was a challenge in the recent years and there is no consensus on its efficacy (
1). Immediate surgical decompression of the injected site (usually a digit) should be done. All injected foreign and devital necrotic tissues should be removed with delicate dissection. The wound should be irrigated with enormous amount of normal saline without using a chemical solvent. The wound should be left open for a second look, which should be 48 - 72 hours later. This sequence of procedures should be done until a highly vascular and infection-free bed is available for the final operation. The nature and extent of the injury as well as the outcome of the multiple irrigation and debridement dictate the kind of the final procedure, which can be a simple skin graft or a more challenging reconstructive procedure ( 4, 5). This algorithmic approach was used for all of our patients.
The outcome after a high-pressure injection injury is reportedly disappointing. Amputation rate is high and the injury burdens devastating sequels, which downgrade the function of the hand (
3). According to the literature, a small percentage of injured patients can resume their original work and duties ( 10). In our series two out of nine patients were able to continue their previous job. This indicates the devastating nature of this kind of injuries.
There are several shortcomings for our study. The size of the series is small and also the follow up period is not long-term. Thus future studies should recruit patients by running a multiple center study and follow the patients in the long-term.
This study emphasizes the findings of previous studies that urge clinicians to not underestimate these benign looking injuries and perform immediate surgical decompression alongside other classic recommendations.