High-pressure injection injury of the hand: an often underestimated trauma: case report with study of the literature

There are several mechanisms responsible for the irreversible damage of the tissues:

Firstly, the pressure plays an important role. In the literature it varies from 40 to 800 bar [10, 16]. A pressure of 7 bar is already sufficient to penetrate the skin. At higher pressures, direct contact with the skin is not necessary to infiltrate the subcutaneous tissues [13]. The injected fluid spreads along the neurovascular bundles through places with the lowest resistance [17]. This causes a traumatic dissection of the finger and compression of the neurovascular bundles with vascular spasms, tissue ischemia and thrombosis as a consequence. If the distension of the tissues, caused by the fluid itself and by swelling and oedema, creates a pressure build-up exceeding hydrostatic pressure, tissue perfusion will be limited similar to that of compartment syndrome.

Secondly, there is the chemical damage by the fluid himself. Some fluids have cytolytic properties and can cause tissue destruction, necrosis and intense inflammatory responses. Fibrosis arises around the tissues and can result in a strong restriction of the hand function [5, 7, 10, 16].

A final factor which plays a role in the vast destruction of tissues is infection. This can occur primarily during the injection, but more often it is a secondary infection that occurs. Ischemia and necrosis facilitate this secondary infection [7, 17]. The use of antibiotics which should cover both gram-positive and gram-negative organism is indicated [4]. The application of corticosteroids has no effect on the presence of infection and does not affect the incidence of amputation [2].

Initially there are only minimal complaints. Mostly there is only a small punctiform skin lesion. After some hours swelling, pain, functio laesa and sensibility impairments appear. Finally, a dysfunction of the perfusion occurs. The initially mild symptoms lead to a delay of treatment and so subcutaneous damage can spread out, increasing the chance on permanent complications and amputation. On average patients are seeing a doctor only after 9 h. The fluid can damage the soft tissues and can spread to neighbouring structures. When the injection takes place at the pink or small finger, the fluid can spread along the synovial sleeves like in a V-phlegmona [9, 13].

In literature some rare cases are described. There was a patient who developed a pneumomediastinum after injection of air in the hypothenar [13, 14]. Some rare perversions of granulomes, a sequel after a high-pressure injection injury by intense inflammatory response, in squameus carcinomas is also given [13, 15].

The factors influencing the prognosis of the final hand function are mainly stipulated by the circumstances of the accident:

Firstly, information about the fluid’s nature is to be gathered to exclude a general intoxication. If needed, contact with an anti-poison-centre can give information about an anti-dotum. Vital parameters must be followed up. The general systemic responses which can occur among others are renal failure, intoxication with lead, allergic responses and haemolysis. There is a big danger for intoxication in case of an injection with white-spirit or terebentine [16].

Most of the authors agree that only a fast and wide exploration under general anaesthesia or plexus block is the suitable treatment for a high-pressure injection injury [2, 3]. Pushing the fluid to the outside or making relieving incisions for decompression is insufficient to prevent additional subcutaneous damage. Ring block of the finger should be avoided because of the possibility of further vascular compression and vasospasm by the extra injected volume [9, 13]. All injected material and necrotic substances must be removed, followed by a saline irrigation. The use of a solvent to remove the fluid is no solution, because most of the solvents themselves have cytolytic properties and can cause additional damage to the weak tissues. The procedure occurs under tourniquet but without using the Esmarch bandage for exsanguination of the arm to avoid further spreading of the injection material along the tendon sheaths and neurovascular bundles [13, 15]. There must be an optimalisation of the vascularisation of the injected hand. Therefore application of ice to reduce swelling is dissuaded (Table 1). Regional anesthesia of the stellate ganglion and brachial plexus produces analgesia and vasodilatation of peripheral arteries by inhibition of the sympathic tone [23]. If there is already a loss of sensibility and a poor vascularisation at arrival in the emergency department, immediate amputation must be discussed with the patient [16]. Frequently there is a need for several debridements or a reconstruction by means of skin grafts, local or free flaps [8, 24]. Sometimes there is a preference to open wound technique with regular salvage of the wound [8]. With this technique Pinto et al. had only an amputation risk of 16%, which lies much lower than the amputation risk that is described in other articles [2, 3, 12]. They applied the same wide exploration and debridement with leaving the wound open and regularly salvage in combination with early intensive physiotherapy treatment in all cases [8].

In the study of Wong et al. the injection injuries were divided in mild, moderate and serious cases, based on the nature of the fluid, the latency time to adequate treatment and the clinical neurovascular status at arrival. Mild injuries can be treated conservatively with broad spectrum antibiotics, tetanus prophylaxis and observation of the neurovascular situation of the fingers. Patients with moderate or serious injuries underwent immediate surgical exploration and decompression with wide debridement in combination with antibiotics and tetanus prophylaxis. Six of seven mild injuries could be well treated with conservative therapy. One nevertheless still needed a surgical exploration. Sixteen patients with a moderate injury had good results. At three of the five serious high-pressure injection injuries an amputation could not be avoided. The other two had good results [24].

Preoperative X-rays can show the quantity and distribution of radio-opaque fluids. The distribution of radiolucent substances can sometimes be shown on X-rays by subcutaneous emphysema [7]. At arrival in the hospital a tetanus prophylaxis and antibiotic prophylaxis, under the form of 3e a generation cephalosporine must be administered. In literature a controverse concerning the use of corticosteroids for high-pressure injection injuries exists. There is a theoretical evidence for the use of corticosteroids in the case of intense inflammatory reactions and at late presentations with diffuse oedema and erythema. Corticosteroids can avoid an acute response to the strange fluid and functional sequels [15]. In the study of Lewis et al. all patients received 100 mg hydrocortisone/6 h intravenously and later 25 mg prednisolone/24 h orally while diminishing the concentration in order to stop within 3–5 days. [16] Other authors dissuade the use of corticosteroids because of the possible disadvantages. Corticosteroids oppress the leukocyte response and raise the infection risk. The chance on infection increases more within necrotic tissues and diminished vascularisation [24, 25]. A recent review of the literature [2] however shows, that the application of corticosteroids has no effect on the presence of infection and does not affect the incidence of amputation [2].

Postoperative the patient receives a palmar splint. It is very important to start immediately with physiotherapy to build up the hand function as well as possible. In the first three weeks patients only receive active and passive mobilisation of the fingers. After three weeks they can start with an intensive physiotherapeutic scheme for 6 up to 12 months.

The outcome after a high-pressure injection injury is frequently disappointing, even after immediate adequate treatment. The patient has to be informed previously concerning the possible restrictions in hand function and the chance on finger amputation. The amputation risk is valued on 16–55%. With solvents it goes up to 50–80% [12, 13, 16]. When there are already impairments of the vascularisation during the first medical examination or when the pressure was more than 490 bar, amputation risk reaches the 100% [13]. Permanent complaints of the patient among others are hyperesthesia, continuous pain, cold intolerance, contracture, and reduced sensitivity. Amputation and aesthetic problems are two other complications. Only a small percentage of the patients can resume its original work [10].