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High pressure injection injuries, the problems, pathogenesis and management
High Pressure Injection Injuries, the Problems, Pathogenesis and Management--H. D. Kau[man
HIGH P R E S S U R E INJECTION INJURIES, T H E PROBLEMS, PATHOGENESIS AND MANAGEMENT
H. D. K A U F M A N , Liverpool INTRODUCTION
The introduction of new machinery and plant into modern industry is geaerally followed by increased or more effective production. Accompanying this obvious advantage however there often follows a crop of hitherto unencountered industrial injuries. This sequence of events is well demonstrated when considering the group of injuries loosely classed as "High Pressure Injection Injuries". The first of this group was initially described by Rees in 1937, the apparatus responsible being the fuel injection mechanism of a diesel engine. Two years later F. H. Smith reported a case in which the high pressure grease gun was the causative agent (Smith 1939). Finally the high pressure spray gun was introduced into commercial use and in 1963 Gruner recorded the case histories of several victims (Gruner 1963). In spite of the fact that the contents of the high pressure spray guns were often toxic, it was not until 1966 that systemic effects were noticed following injury; such a case was reported by the author (Kaufman and Williams 1966). The three types of apparatus mentioned above account for the bulk of the recorded injuries, but in addition there are a few miscellaneous causes. Although the total number of these appliances in use throughout the world is enormous, the numbers of cases either reported or encountered in clinical practice is paradoxically very low. A review of the literature plus personal cases brings the total number of injuries published to fifty-one, the majority being caused by the grease gun (Table I). This is not altogether surprising since either semi-skilled o r non-skilled workers usually grease a car. In contrast to this is the fact that diesel fuel injectors are adjusted and repaired by skilled mechanics and the number of injuries involving this apparatus is correspondingly lower. TABLE I Appliances
APPLIANCES RESPONSIBLE FOR INJURY Cases
Grease Guns . . . . . . . . . . . . . . . . . . . . . Spray Guns ..................... Diesel Fuel Injectors . . . . . . . . . . . . . . . . . . Miscellaneous . . . . . . . . . . . . . . . . . . . . . Valve of grease box of Caterpillar tractor . . . . . . Fractured oil well pipe line ............ Jet of carbonox at high pressure in oil well works ... Oil pipe defect . . . . . . . . . . . . . . . . . . Defective armoured tubing leading to hydraulic ramp
29 9 7
TOTAL
51
Percentage
57 18
14 11
1 1 1 1 2 m
100
The clinical history of the condition is fairly typical, males virtually always being the victims. With occasional exceptions the hands only are involved (Table II), the left twice as often as the right, with a preponderance of terminal segment involvement (Tables III and IV). Overall the terminal segments of the left index and middle fingers have the highest rate of injury. 63
High Pressure Injection Injuries, the Problems, Pathogenesis and Management--H. D. Kaufman
TABLE II FIFTY-TWO SITES OF INJURY IN 51 ACCIDENTS ALL APPLIANCES CONSIDERED Palm ...... Thumb ...... Index Finger Middle Finger Ring Finger Little Finger Orbit ...... Forearm ...... Unknown Site
Left
Right
6
1
1
l
1
-
13 10
6 5
-
...... ...... ... ... ... ...
. . . . . .
......
...
Unknown
Side
1
. . . . . .
1
l
-
. . . . . .
0 2
-
......
0 0
. . . . . .
1
0
......
0
0
2
32
16
4
TOTAL
-
TABLE III INCIDENCE OF INJURIES TO LEFT AND RIGHT SIDES Cases
Left ...... Right ...... Unknown ...
Percentage
32 15 4
63 29 8
TABLE IV SEGMENT INVOLVED IN INJURIES TO THE FINGERS Terminal Middle Proximal
......... ......... .........
Left
Right
16 2 3
4 2 2
Unknown
side
1 -
A s a g e n e r a l rule the i n j u r y occurs at w o r k a n d in spite of the forces involved ( G r u n e r 1963, K a u f m a n 1966) the i m m e d i a t e s y m p t o m s a r e m i n i m a l , the initial i m p a c t being quite painless o r at m o s t a stinging in the affected p a r t being noted. D e p e n d i n g u p o n the q u a n t i t y of foreign m a t e r i a l injected, the affected p a r t (which is u s u a l l y a finger) b e c o m e s i n s t a n t a n e o u s l y distended. A short while l a t e r the d i g i t b e c o m e s p ~ t e , ~ m o r e swollen a n d n u m b . Because the a p p e a r a n c e s of the i n j u r e d p a r t a r e n o t very o u t s t a n d i n g the gravity of the injury is often n o t a p p r e c i a t e d . E x a m i n a t i o n reveals a swollen finger with a p u n c t u r e site a b o u t the size of a p i n h e a d f r o m which the injected m a t e r i a l can be seen oozing. Pressure o n the s u r r o u n d i n g a r e a causes f u r t h e r e x u d a t i o n of the grease f r o m the wound. I n a d e q u a t e l y t r e a t e d the clinical course is v a r i a b l e b u t the p a t i e n t soon c o m plains of t h r o b b i n g p a i n w h i c h b e c o m e s intense, often r e q u i r i n g o p i a t e s o r even a nerve plexus b l o c k to afford relief. C o n t i n u a t i o n with e x p e c t a n t t r e a t m e n t is d o o m e d to failure, whilst a c c e p t e d surgical m a n a g e m e n t has a v e r y high m o r b i d i t y a n d a n o v e r a l l p o o r success rate. T h e m a n a g e m e n t will be d e a l t with m o r e fully l a t e r on in this p a p e r . Because the p r o g n o s i s a p p e a r e d so very p o o r , a series of e x p e r i m e n t s was designed to investigate the m a g n i t u d e of the p r o b l e m , the reasons for the i n a d e q u a t e o u t c o m e , a n d if possible to indicate a r a t i o n a l line of t r e a t m e n t . 64
High Pressure Injection Injuries, the Problems, Pathogenesis and Management--H. D. Kaufman MATERIALS
The injuries were inflicted on selected sites in the human cadaverous hand, using a high pressure spray gun unit at an effective nozzle pressure of 750 lbs. per sq. in. The motive force was provided by a cylinder of compressed air with a delivery pressure of 40 p.s.i, which was boosted to the above ejection pressure by means of a compressor incorporated in the spray gun unit. The material injected was a mixture of white spirit and wax in commercial use, which was stained green for ease of recognition. The machine was so adjusted that only one shot of wax was delivered at a time, the stream issuing through an orifice of 1/20,000 inch in diameter. METHODS
The gun was held either lightly in contact with, or close to, the area to be injected and the trigger was released. After injection skin flaps were reflected and an anatomical dissection performed with particular reference to the relationship of the wax mixture to (a) the normal tissue planes, (b) the digital vessels and nerves and (c) the tendons and tendon sheaths. The results were recorded photographically both in colour and monochrome, using a single lens reflex camera system, equipped with extension tubes and an 85 mm lens. The numbers of experimentally produced injuries at each site are shown in Table V.
TABLE
V NUMBER
OF
Index, Middle
EXPERIMENTAL
INJURIES
and Ring Fingers:
INFLICTED
AT
EACH
Distal Phalanx . . . . . . . . Middle Phalanx . . . . . . . . Proximal Phalanx . . . . . . . . Thumb: Distal Phalanx . . . . . . . . Proximal Phalanx . . . . . . . . Little Finger: Distal Phalanx :. . . . . . . Middle Phalanx . . . . . . . . Proximal Phalanx . . . . . . . . Mid Palmar Region: . . . . . . . . . . . . . . . . . . . . . . . . Thenar Eminence: . . . . . . . . . . . . . . . . . . . . . . . . Hypothenar Eminence: . . . . . . . . . . . . . . . . . . . . .
. . . . . . . .
SITE 3 4 4 1 2 1 2 2 3 3 3
A P P L I E D ANATOMY The important feature of the anatomy of the finger in the context of these experiments is the various layers which can be identified and the different strength of the tissues comprising these layers. Thus passing from superficial to deep on the flexor surface there is skin, subcutaneous fat, flexor tendon sheath, synovial sheath, tendons and bone. The flexor sheath extends from the base of the proximal phalanx to that of the terminal phalanx and encloses both the superficial and deep flexor tendons binding them to the volar surface of the individual phalangeal bones. The sheath is not however of uniform consistency, that part overlying the centre of the phalanx being quite fibrous and rigid, whilst the segment overlying an interphalangeal joint is thin and flexible.
65
High Pressure Injection Injuries, the Problems, Pathogenesis and Management--H. D. Kaufman
Within the flexor sheath lies the delicate synovial sheath which in the index, middle and ring fingers has blind ends at about the level of the metacarpophalangeal joint proximally and just beyond the insertion of the flexor profundus distally. The synovial sheaths of the thumb and little finger extend proximally to the radial and ulnar bursae respectively thus differing from the middle three digits which can from this standpoint be classed together. In the palm the point of importance is the fact that the superficial and deep palmar spaces do not communicate radially with thenar eminence nor medially with hypothenar space.
Fig. 1
High pressure injection injury, External appearance.
Fig. 2
Subcutaneous spread of wax in finger.
Fig. 3a & 3b Tendon sheath opened showing long flexor tendons surrounded by wax. RESULTS
Injection over the fibrous flexor sheath of any finger Following injection the most striking feature was the small puncture wound at the site of entry through which some wax exuded. Surrounding this point there was quite a marked distension of the digit which extended for some considerable distance in both proximal and distal directions (Fig. 1). 66
High Pressure Injection Injuries, the Problems, Pathogenesis and Management--H. D. Kaufman Removal of the overlying skin showed the extensive distribution of the wax in the superficial tissues. The wax spread both longitudinally and laterally within the finger, thereby completely encircling the digit. Naturally, the amount of wax on the dorsal surface was less than that on the anterior aspect. In the midst of the wax the digital nerves and vessels could be seen (Fig. 2) and often the site of the impact on the fibrous sheath could be seen. Injection site around the skin creases of the digit i.e. over the thinner part o[ the flexor sheath Because of the lesser resistance offered at this point by the flexor sheath, the stream of wax was not stopped and penetration of the synovial sheath caused this structure to be distended with wax and the enclosed tendons to be surrounded by the foreign material (Fig. 3a and 3b). There were thus two levels of spread in this case:-(i) in the superficial tissues as previously, and (ii) in the deeper plane as described above. Joints were not entered on any occasion in this series of experiments but it should be appreciated that a relatively low injection pressure of 750 p.s.i, was used. It is possible that with the higher pressures encountered in industry, articular damage might well occur. Eccentric Site of Injury of any finger From time to time the direction of the injection was such that the stream of wax passed right through the finger lateral to the bone, emerging via a gaping exit would on the opposite side of the digit. In addition the superficial spread was quite extensive, the dorsal surface of the finger and the extensor tendon being heavily surrounded. Thumb and Little Finger With the thumb and little finger the injuries produced much the same effects as described above, with the exception that if the tendon sheaths were penetrated, then the radial and ulnar bursae were respectively contaminated by retrograde spread. Mid-Palmar Region So that the mid-palmar spaces would be entered, the injection site was selected between the third and fourth metacarpals midway between the two transverse
Fig. 4
Superficial spread of wax in the palm. 67
High Pressure Injection Injuries, the Problems, Pathogenesis and Management--H. D. Kaufman
palmar skin creases. Immediately beneath the skin the tough palmar aponeurosis caused a fair amount of lateral spread, but the structure was penetrated nevertheless and a deeper spread also ensued. Fig. 4 shows how the superficial spread was confined to the boundaries of the palmar aponeurosis extending in triangular fashion to its apex at the heel of the palm, radially to the edge of the thenar eminence and medially to the fourth interosseous space. The base of the triangle was formed by a line crossing the palm at the heads of the metacarpal bones. Removal of the aponeurosis showed the penetration and spread at a deeper level with the m a x i m u m concentration of wax in the third interosseous space. The superficial palmar arch and its branches together with the digital nerves were all intimately surrounded by wax (Fig. 5). As the various layers of the hand were dissected the wax was still found penetrating right through to the dorsal aspect of the hand (Figs. 6 and 7). There was no extension distally beyond the transverse ligament of the palm nor proximally beyond the flexor retinaculum.
Fig. 5
Maximum amount of grease in the third interosseous space.
Fig. 6 Fig. 7
Superficial tendons and some of the lumbrical muscles surrounded by wax. Deep tendons and lumbrical muscles surrounded by wax.
Thenar and Hypothenar Eminences
When either of these areas were injected, the overall contour of the area was maintained even though the part was distended (Fig. 8). In both cases transgression of the wax into the mid-palmar spaces did not occur, but the intrinsic musculature of the eminences were thoroughly impregnated with the wax. In the case of the thenar eminence the tendon of the flexor pollicis longus and the neurovascular bundle to the first interosseous space were surrounded by the wax (Fig. 9). 68
High Pressure Injection Injuries, the Problems, Pathogenesis and Management--H. D. Kau[man
Fig. 8 Fig. 9
Injections of wax into both eminences. No extension of wax into mid-palmar region. Wax around flexor pollicis longus tendon and the digital vessels and nerves. DISCUSSION
The stream of wax emitted from a high pressure injection apparatus is in the form of a fine jet, which in the case of the spray gun and grease gun, is modified by the application of a nozzle. Injury occurs as a result of accident, negligence or ignorance, particularly when the nozzle has been removed for some reason or another. Penetration of the skin occurs easily and close contact between the skin and the gun is not necessary, a gap of an inch or so being compatible with severe damage. Having entered, the wax continues in its line of fire with little lateral spread, until a resistant structure is encountered, which cannot be penetrated. At this point the wax is deflected from its path and spreads along the tissue planes of the level in question. Regardless of the site of injection certain characteristics are always noticed. 1. A typical puncture wound exuding wax. 2. Local distension of the part injected. 3. Spread along a superficial plane beneath the skin. 4. Spread along a deeper plane, the level of which depends on the tissues encountered by the stream of wax. It was found in the above experiments that it was possible to enter the tendon sheath at will depending on the injection site selected. From this it would be possible to predict the likelihood of tendon sheath involvement in actual live injuries and the appropriate action taken. When pressures of 5-10,000 lbs./sq, in. are involved, the tendon sheath must always be at risk and this point should be remembered. The experiments in the palm show that it would appear to be unnecessary to explore any other space than the one involved by the injection, as the lateral distribution occurs with insufficient force to transgress the limiting structures. The extent of lateral spread within a particular tissue space or plane is determined by the size of the space involved. The relationship between the ejection pressure and the velocity of the stream of wax is governed by the equation. V=v'2gp/K (Gruner 1963) Where V----velocity in feet per second g=acceleration due to gravity, i.e. 32 ft./sec./sec. p--ejection pressure in lbs. per sq. in., and K--density of the injected material in lbs. per cu. ft. 69
High Pressure Injection Injuries, the Problems, Pathogenesis and Management--H. D. Kaulman
If for the purposes of the calculation we imagine that instead of wax, water was the material injected, then a range of velocities which might be encountered in industry could easily be calculated. Thus considering the grease gun operating at pressures up to 10,000 p.s.i. (10,000 x 144 lbs./sq, ft.) and water with a density of 6.24 x 10 lbs./cu, ft. V = / 2 x 32 x 104 x 144 = 1,360 ft./sec. / or 928 m.p.h. V' 6.24 x i0 Similarly the ejection velocity of the spray gun in use during the experiments would be calculated to be 332 ft./sec, i.e. approx. 225 m.p.h. As the specific gravity of the actual injected greases is not far removed from that of water (1.0) the velocities met with in practice would be of a similar order. Approximately one gram (0.036 oz.) of wax entered the finger at each shot, the limiting factors being the capacity of the finger and the fact that the digit is deflected out of the line of fire by the force of the stream. The palm usually corrtained about five grams of wax (0.18 oz.). The Kinetic energy which is dissipated on impact can be determined from the formula K.E.=½ mv 2, where m is the mass of wax ejected and v is the velocity of impact. Thus in the case of a finger injured by a stream of wax issuing at 10,000 p.s.i, the energy expended would be 2,040 ft. lbs. this value being approximately equivalent to a ton weight falling from a height of about ten inches. With a large amount of wax being considered as in the palm, then the figures would be correspondingly higher. Appreciating the magnitude of the forces the following was said by Golay and Verdan "I1 faut donc se m6fier de l'embout du graisseur, de l'injecteur du moteur Diesel, comme du canon d'un fusil charg6!" One should therefore mistrust the nozzle of the grease gun and fuel injector of the Diesel engine, like the barrel of a loaded gun (Golay and Verdan 1956). Some time ago Mason and Queen (1941) in their paper on the subject arbitrarily divided the local clinical symptoms and findings into three stages, v i z : - acute, intermediate and late. In spite of the elapse of almost thirty years this classification has not yet been bettered.
Acute Stage This represents the acute onset and immediate symptoms due to the entry into the tissues of a foreign material under high pressure. The initial swelling of the part is due to the introduction of the foreign material and the resultant inflammatory response with accompanying oedema. Following on the distention the tissues become white and anaesthetic and undoubtedly this is due to local interference with the vascular supply of the affected part. Many suggestions have been made as to the reason for the arterial insufficiency, but irrespective of the operating mechanism the resultant vascular changes impair the viability of the part. In addition the effects of the ensuing chemical inflammation and superimposed secondary infection cause tissue necrosis and contribute further towards gangrene. The sequence of events can b~e expressed diagrammatically as shown in Diagram 1.
Intermediate Stage This follows the acute phase and is characterised by the formation of oleogranulomata around the site of the injection. These oleomata are nodular tumours which arise as a result of a foreign body tissue reaction to the injected material (Fig. 10). They may remain without apparent change for many years but an associated fibrosis occurs which causes considerable loss of function and mobility of the affected part. 70
High Pressure Injection Injuries, the Problems, Pathogenesis and Management--H. D. Kau[man
Pallor
Numbness
',,
/
DIAGRAM 1 Intravascular Thrombosis
Destruction of vessels
Spasm of" vessels
Physical distention Injected material Chemi!al irritation
Circulatory Embarrassment
/
Acute Inflammation
~ Gang~rene
Pain
Secondary bacterial infection Sequence of vascular changes following high pressure injection injuries (Adapted from Smith, M. G. H., 1964)
Fig. 10
Histological appearance of oleogranuloma.
Late Stage
With the passage of time there occurs a breakdown of the skin over the oleomata, resulting in the formation of widespread cutaneous and subcutaneous lesions, ulcers and persistent sinuses occur which discharge an amorphous material consisting of grease and epithelial debris which is sterile on culture. The sinuses become secondarily infected and eventually the skin of the digit is much thickened and pitted, being both functionally and cosmetically poor. As a late complication malignant change may occur in the sinuses, the histology being squamous epithelioma (Vinogradov 1936). The intermediate and late stages can also be represented diagrammatically (Diagram 2). DIAGRAM 2 Chronic inflammation r-Fibrosis ~ Loss of function Chemical irritation
f
~ ' ~ Foreign body granuloma -- Sinuses ~ Malignancy Diagrammatic representation of intermediate and late stages (Adapted from Smith, M. G. H., 1964) 71
High Pressure Injection Injuries, the Problems, Pathogenesis and Management--It. D. Kaufman MANAGEMENT
Irrespective of the apparatus responsible for the injury the prognosis is poor and the morbidity considerable. It is convenient to consider the morbidity as that period elapsing from the time of the accident to complete healing and return to work. With all methods of treatment the morbidity resulting from forty injuries caused by all types of appliance, ranged from one month to two years. The so far accepted management of these injuries can be divided into: (a) conservative and/or local drainage of the affected area, (b) early amputation, usually because of gangrenous changes. On an average those patients treated by more conservative methods had a morbidity of about six months with a range of one month to two years, whilst the average time required for complete healing and return to work following early amputation was one and a half to two months. It has been demonstrated in the earlier part of this paper that following a high pressure injection injury the initial physical destruction is so great that a return to normality is precluded. This fact together with the lesser morbidity associated with radical surgery leads me to believe that the primary treatment for this condition should be immediate amputation of the affected digit. Naturally occasions will arise where this form of management is not acceptable e.g. thumb and palm, and in such circumstances wide exploration and evacuation of as much foreign material as possible is the treatment of choice, but skin grafting either immediately or later may be required. Should the synovial sheath of either the thumb or little finger be penetrated it is recommended that the radial or ulnar bursa respectively be irrigated with warm physiological saline to remove as much grease as possible. The cleaning of the sheath in this manner is purely mechanical and the use of chemical agents such as fat solvents is not advised. All surgical manoeuvres should be conducted in a bloodless field. Because compression of the part and further impregation of the tissues is likely to occur with the use of an Esmarch's bandage, this latter method of exsanguination should be avoided and instead the arm elevated for about 10 minutes before applying a tourniquet proximal to the site of the injury. In addition to the purely surgical aspect of the management, general therapeutic measures should also be used. Broadly speaking the latter fall into the use of three main groups of drugs.
Analgesics The injury both pre- and post-operatively is extremely painful, and in addition to morphia and pethidine, nerve blocks may be necessary. Local ring blocks should not be used as they will increase the local distension of the part, but on the other hand brachial plexus block is extremely effective in relieving pain. This method has been personally used with considerable success and does not appear to have been recorded previously.
Anti-In[ective Although even garage grease is sterile to culture, the prevention of secondary infection is important and the prophylactic administration of a broad spectrum antibiotic is suggested.
A nti-lnflammatory In an effort to minimise the considerable inflammatory response consequent upon the chemical irritation and secondary bacterial infection various drugs of this class have been used. Of these Tanderil (oxyphenbutazone--Geigy) was considered to be worthy of further trial. Bottoms (1962) using steroids (dexamethasone) claimed considerable success and recommended further usage of this class of drug. 72
High Pressure Injection Injuries, the Problems, Pathogenesis and Management--H. D. Kau[man GENERAL SUPPORTIVE MEASURES
Although systemic effects following injury have only been recorded on one occasion (Kaufman 1966), the increased use of high pressure spray guns for the delivery o f a variety of substances, many of which are toxic, would suggest that others will be encountered. The treatment is largely resuscitative and somewhat empirical, the clinical picture varying according to the toxic material absorbed. If severe toxaemia occurs urinary function should be observed to detect any signs of renal damage and similarly routine liver function tests would help detect any gross degree of liver damage that might be caused by substances such as industrial solvents. If intravenous therapy were required, five per cent dextrose and isotonic saline are adequate and should be administered according to the patient's fluid balance requirements and renal function. SUMMARY
A series of experiments were conducted to demonstrate the damage occurring following upon high pressure injection injuries. In addition to this an account of the clinical picture and prognosis was detailed, based on personal cases and a review of the literature. Finally the management of the condition was reviewed and in the light of the experimental evidence certain lines of treatment were suggested. ACKNOWLEDGEMENTS
The work in this paper formed the major part of the thesis for the degree of Ch.M. submitted to and accepted by the University of Liverpool. In addition it has to a large extent already been published in the British Journal of Surgery. Kaufman, 1966, 1968, a and b). Figs. 2 and 3 are reproduced through the generosity of the Editor and the Publishers of the British Journal of Surgery, John Wright and Sons Ltd., Bristol. REFERENCES BOTTOMS, R. W. A. (1962), A case of High Pressure Hydraulic Tool Injury to the Hand, its Treatment aided by Dexamethasone and a plea for a further trial of this substance. Medical Journal of Australia, 2: 591. GOLAY, L. and V E R D A N , C. (1956). Mortification tissulaire par jet de mazout. Zeitschrift ftir Unfallmedizin and Berufskankheiten. Revue des accidents du travail et des maladies professionelles, 49:115. G R O N E R , O. P. N. (1963). Sproyte- og Smorepistol skader. Skader ved hoytrykksprut fra sma apninger, oppstaelsesmate og behandling. Tidsskrift for den Norske Laegeforening, 83: 1263. K A U F M A N , H. D. (1966). A study of High Pressure Injection Injuries. Ch.M. Thesis, University of Liverpool. K A U F M A N , H. D. (1968) (a). The Clinicopathological Correlation of High-Pressure Injection Injuries. British Journal of Surgery, 55: 214. K A U F M A N , H. D. (1968) (b). The Anatomy of Experimentally Produced High-Pressure Injection Injuries of the Hand. British Journal of Surgery, 55: 340. K A U F M A N , H. D. and WILLIAMS, H. O. (1966). Systemic Absorption from High-Pressure Spray-Gun Injury. British Journal of Surgery, 53: 57. MASON, M. L. and QUEEN, F. B. (1941). Grease Gun Injuries to the Hand, Pathology and Treatment of Injuries (Oleomas) Following the Injection of Grease Under High Pressure. Quarterly Bulletin of Northwestern University Medical School, 15: 122. REES, C. E. (1937). Penetration of Tissue by Fuel Oil Under High Pressure from a Diesel Engine. Journal of the American Medical Association, 109: 866. SMITH, F. H. (1939). Penetration of Tissue by Grease Under Pressure of 7000 Pounds. Journal of the American Medical Association, 112: 907. SMITH, M. G. H. (1964). Grease Gun Injury. British Medical Journal, 2: 918. V I N O G R A D O V , I. (1936). Ober Sp~itfolgen Ktinstlicher Oleogranulome. Archiv ftir Klinische Chirurgie, 187: 69.
73
HIGH P R E S S U R E INJECTION INJURIES, T H E PROBLEMS, PATHOGENESIS AND MANAGEMENT
H. D. K A U F M A N , Liverpool INTRODUCTION
The introduction of new machinery and plant into modern industry is geaerally followed by increased or more effective production. Accompanying this obvious advantage however there often follows a crop of hitherto unencountered industrial injuries. This sequence of events is well demonstrated when considering the group of injuries loosely classed as "High Pressure Injection Injuries". The first of this group was initially described by Rees in 1937, the apparatus responsible being the fuel injection mechanism of a diesel engine. Two years later F. H. Smith reported a case in which the high pressure grease gun was the causative agent (Smith 1939). Finally the high pressure spray gun was introduced into commercial use and in 1963 Gruner recorded the case histories of several victims (Gruner 1963). In spite of the fact that the contents of the high pressure spray guns were often toxic, it was not until 1966 that systemic effects were noticed following injury; such a case was reported by the author (Kaufman and Williams 1966). The three types of apparatus mentioned above account for the bulk of the recorded injuries, but in addition there are a few miscellaneous causes. Although the total number of these appliances in use throughout the world is enormous, the numbers of cases either reported or encountered in clinical practice is paradoxically very low. A review of the literature plus personal cases brings the total number of injuries published to fifty-one, the majority being caused by the grease gun (Table I). This is not altogether surprising since either semi-skilled o r non-skilled workers usually grease a car. In contrast to this is the fact that diesel fuel injectors are adjusted and repaired by skilled mechanics and the number of injuries involving this apparatus is correspondingly lower. TABLE I Appliances
APPLIANCES RESPONSIBLE FOR INJURY Cases
Grease Guns . . . . . . . . . . . . . . . . . . . . . Spray Guns ..................... Diesel Fuel Injectors . . . . . . . . . . . . . . . . . . Miscellaneous . . . . . . . . . . . . . . . . . . . . . Valve of grease box of Caterpillar tractor . . . . . . Fractured oil well pipe line ............ Jet of carbonox at high pressure in oil well works ... Oil pipe defect . . . . . . . . . . . . . . . . . . Defective armoured tubing leading to hydraulic ramp
29 9 7
TOTAL
51
Percentage
57 18
14 11
1 1 1 1 2 m
100
The clinical history of the condition is fairly typical, males virtually always being the victims. With occasional exceptions the hands only are involved (Table II), the left twice as often as the right, with a preponderance of terminal segment involvement (Tables III and IV). Overall the terminal segments of the left index and middle fingers have the highest rate of injury. 63
High Pressure Injection Injuries, the Problems, Pathogenesis and Management--H. D. Kaufman
TABLE II FIFTY-TWO SITES OF INJURY IN 51 ACCIDENTS ALL APPLIANCES CONSIDERED Palm ...... Thumb ...... Index Finger Middle Finger Ring Finger Little Finger Orbit ...... Forearm ...... Unknown Site
Left
Right
6
1
1
l
1
-
13 10
6 5
-
...... ...... ... ... ... ...
. . . . . .
......
...
Unknown
Side
1
. . . . . .
1
l
-
. . . . . .
0 2
-
......
0 0
. . . . . .
1
0
......
0
0
2
32
16
4
TOTAL
-
TABLE III INCIDENCE OF INJURIES TO LEFT AND RIGHT SIDES Cases
Left ...... Right ...... Unknown ...
Percentage
32 15 4
63 29 8
TABLE IV SEGMENT INVOLVED IN INJURIES TO THE FINGERS Terminal Middle Proximal
......... ......... .........
Left
Right
16 2 3
4 2 2
Unknown
side
1 -
A s a g e n e r a l rule the i n j u r y occurs at w o r k a n d in spite of the forces involved ( G r u n e r 1963, K a u f m a n 1966) the i m m e d i a t e s y m p t o m s a r e m i n i m a l , the initial i m p a c t being quite painless o r at m o s t a stinging in the affected p a r t being noted. D e p e n d i n g u p o n the q u a n t i t y of foreign m a t e r i a l injected, the affected p a r t (which is u s u a l l y a finger) b e c o m e s i n s t a n t a n e o u s l y distended. A short while l a t e r the d i g i t b e c o m e s p ~ t e , ~ m o r e swollen a n d n u m b . Because the a p p e a r a n c e s of the i n j u r e d p a r t a r e n o t very o u t s t a n d i n g the gravity of the injury is often n o t a p p r e c i a t e d . E x a m i n a t i o n reveals a swollen finger with a p u n c t u r e site a b o u t the size of a p i n h e a d f r o m which the injected m a t e r i a l can be seen oozing. Pressure o n the s u r r o u n d i n g a r e a causes f u r t h e r e x u d a t i o n of the grease f r o m the wound. I n a d e q u a t e l y t r e a t e d the clinical course is v a r i a b l e b u t the p a t i e n t soon c o m plains of t h r o b b i n g p a i n w h i c h b e c o m e s intense, often r e q u i r i n g o p i a t e s o r even a nerve plexus b l o c k to afford relief. C o n t i n u a t i o n with e x p e c t a n t t r e a t m e n t is d o o m e d to failure, whilst a c c e p t e d surgical m a n a g e m e n t has a v e r y high m o r b i d i t y a n d a n o v e r a l l p o o r success rate. T h e m a n a g e m e n t will be d e a l t with m o r e fully l a t e r on in this p a p e r . Because the p r o g n o s i s a p p e a r e d so very p o o r , a series of e x p e r i m e n t s was designed to investigate the m a g n i t u d e of the p r o b l e m , the reasons for the i n a d e q u a t e o u t c o m e , a n d if possible to indicate a r a t i o n a l line of t r e a t m e n t . 64
High Pressure Injection Injuries, the Problems, Pathogenesis and Management--H. D. Kaufman MATERIALS
The injuries were inflicted on selected sites in the human cadaverous hand, using a high pressure spray gun unit at an effective nozzle pressure of 750 lbs. per sq. in. The motive force was provided by a cylinder of compressed air with a delivery pressure of 40 p.s.i, which was boosted to the above ejection pressure by means of a compressor incorporated in the spray gun unit. The material injected was a mixture of white spirit and wax in commercial use, which was stained green for ease of recognition. The machine was so adjusted that only one shot of wax was delivered at a time, the stream issuing through an orifice of 1/20,000 inch in diameter. METHODS
The gun was held either lightly in contact with, or close to, the area to be injected and the trigger was released. After injection skin flaps were reflected and an anatomical dissection performed with particular reference to the relationship of the wax mixture to (a) the normal tissue planes, (b) the digital vessels and nerves and (c) the tendons and tendon sheaths. The results were recorded photographically both in colour and monochrome, using a single lens reflex camera system, equipped with extension tubes and an 85 mm lens. The numbers of experimentally produced injuries at each site are shown in Table V.
TABLE
V NUMBER
OF
Index, Middle
EXPERIMENTAL
INJURIES
and Ring Fingers:
INFLICTED
AT
EACH
Distal Phalanx . . . . . . . . Middle Phalanx . . . . . . . . Proximal Phalanx . . . . . . . . Thumb: Distal Phalanx . . . . . . . . Proximal Phalanx . . . . . . . . Little Finger: Distal Phalanx :. . . . . . . Middle Phalanx . . . . . . . . Proximal Phalanx . . . . . . . . Mid Palmar Region: . . . . . . . . . . . . . . . . . . . . . . . . Thenar Eminence: . . . . . . . . . . . . . . . . . . . . . . . . Hypothenar Eminence: . . . . . . . . . . . . . . . . . . . . .
. . . . . . . .
SITE 3 4 4 1 2 1 2 2 3 3 3
A P P L I E D ANATOMY The important feature of the anatomy of the finger in the context of these experiments is the various layers which can be identified and the different strength of the tissues comprising these layers. Thus passing from superficial to deep on the flexor surface there is skin, subcutaneous fat, flexor tendon sheath, synovial sheath, tendons and bone. The flexor sheath extends from the base of the proximal phalanx to that of the terminal phalanx and encloses both the superficial and deep flexor tendons binding them to the volar surface of the individual phalangeal bones. The sheath is not however of uniform consistency, that part overlying the centre of the phalanx being quite fibrous and rigid, whilst the segment overlying an interphalangeal joint is thin and flexible.
65
High Pressure Injection Injuries, the Problems, Pathogenesis and Management--H. D. Kaufman
Within the flexor sheath lies the delicate synovial sheath which in the index, middle and ring fingers has blind ends at about the level of the metacarpophalangeal joint proximally and just beyond the insertion of the flexor profundus distally. The synovial sheaths of the thumb and little finger extend proximally to the radial and ulnar bursae respectively thus differing from the middle three digits which can from this standpoint be classed together. In the palm the point of importance is the fact that the superficial and deep palmar spaces do not communicate radially with thenar eminence nor medially with hypothenar space.
Fig. 1
High pressure injection injury, External appearance.
Fig. 2
Subcutaneous spread of wax in finger.
Fig. 3a & 3b Tendon sheath opened showing long flexor tendons surrounded by wax. RESULTS
Injection over the fibrous flexor sheath of any finger Following injection the most striking feature was the small puncture wound at the site of entry through which some wax exuded. Surrounding this point there was quite a marked distension of the digit which extended for some considerable distance in both proximal and distal directions (Fig. 1). 66
High Pressure Injection Injuries, the Problems, Pathogenesis and Management--H. D. Kaufman Removal of the overlying skin showed the extensive distribution of the wax in the superficial tissues. The wax spread both longitudinally and laterally within the finger, thereby completely encircling the digit. Naturally, the amount of wax on the dorsal surface was less than that on the anterior aspect. In the midst of the wax the digital nerves and vessels could be seen (Fig. 2) and often the site of the impact on the fibrous sheath could be seen. Injection site around the skin creases of the digit i.e. over the thinner part o[ the flexor sheath Because of the lesser resistance offered at this point by the flexor sheath, the stream of wax was not stopped and penetration of the synovial sheath caused this structure to be distended with wax and the enclosed tendons to be surrounded by the foreign material (Fig. 3a and 3b). There were thus two levels of spread in this case:-(i) in the superficial tissues as previously, and (ii) in the deeper plane as described above. Joints were not entered on any occasion in this series of experiments but it should be appreciated that a relatively low injection pressure of 750 p.s.i, was used. It is possible that with the higher pressures encountered in industry, articular damage might well occur. Eccentric Site of Injury of any finger From time to time the direction of the injection was such that the stream of wax passed right through the finger lateral to the bone, emerging via a gaping exit would on the opposite side of the digit. In addition the superficial spread was quite extensive, the dorsal surface of the finger and the extensor tendon being heavily surrounded. Thumb and Little Finger With the thumb and little finger the injuries produced much the same effects as described above, with the exception that if the tendon sheaths were penetrated, then the radial and ulnar bursae were respectively contaminated by retrograde spread. Mid-Palmar Region So that the mid-palmar spaces would be entered, the injection site was selected between the third and fourth metacarpals midway between the two transverse
Fig. 4
Superficial spread of wax in the palm. 67
High Pressure Injection Injuries, the Problems, Pathogenesis and Management--H. D. Kaufman
palmar skin creases. Immediately beneath the skin the tough palmar aponeurosis caused a fair amount of lateral spread, but the structure was penetrated nevertheless and a deeper spread also ensued. Fig. 4 shows how the superficial spread was confined to the boundaries of the palmar aponeurosis extending in triangular fashion to its apex at the heel of the palm, radially to the edge of the thenar eminence and medially to the fourth interosseous space. The base of the triangle was formed by a line crossing the palm at the heads of the metacarpal bones. Removal of the aponeurosis showed the penetration and spread at a deeper level with the m a x i m u m concentration of wax in the third interosseous space. The superficial palmar arch and its branches together with the digital nerves were all intimately surrounded by wax (Fig. 5). As the various layers of the hand were dissected the wax was still found penetrating right through to the dorsal aspect of the hand (Figs. 6 and 7). There was no extension distally beyond the transverse ligament of the palm nor proximally beyond the flexor retinaculum.
Fig. 5
Maximum amount of grease in the third interosseous space.
Fig. 6 Fig. 7
Superficial tendons and some of the lumbrical muscles surrounded by wax. Deep tendons and lumbrical muscles surrounded by wax.
Thenar and Hypothenar Eminences
When either of these areas were injected, the overall contour of the area was maintained even though the part was distended (Fig. 8). In both cases transgression of the wax into the mid-palmar spaces did not occur, but the intrinsic musculature of the eminences were thoroughly impregnated with the wax. In the case of the thenar eminence the tendon of the flexor pollicis longus and the neurovascular bundle to the first interosseous space were surrounded by the wax (Fig. 9). 68
High Pressure Injection Injuries, the Problems, Pathogenesis and Management--H. D. Kau[man
Fig. 8 Fig. 9
Injections of wax into both eminences. No extension of wax into mid-palmar region. Wax around flexor pollicis longus tendon and the digital vessels and nerves. DISCUSSION
The stream of wax emitted from a high pressure injection apparatus is in the form of a fine jet, which in the case of the spray gun and grease gun, is modified by the application of a nozzle. Injury occurs as a result of accident, negligence or ignorance, particularly when the nozzle has been removed for some reason or another. Penetration of the skin occurs easily and close contact between the skin and the gun is not necessary, a gap of an inch or so being compatible with severe damage. Having entered, the wax continues in its line of fire with little lateral spread, until a resistant structure is encountered, which cannot be penetrated. At this point the wax is deflected from its path and spreads along the tissue planes of the level in question. Regardless of the site of injection certain characteristics are always noticed. 1. A typical puncture wound exuding wax. 2. Local distension of the part injected. 3. Spread along a superficial plane beneath the skin. 4. Spread along a deeper plane, the level of which depends on the tissues encountered by the stream of wax. It was found in the above experiments that it was possible to enter the tendon sheath at will depending on the injection site selected. From this it would be possible to predict the likelihood of tendon sheath involvement in actual live injuries and the appropriate action taken. When pressures of 5-10,000 lbs./sq, in. are involved, the tendon sheath must always be at risk and this point should be remembered. The experiments in the palm show that it would appear to be unnecessary to explore any other space than the one involved by the injection, as the lateral distribution occurs with insufficient force to transgress the limiting structures. The extent of lateral spread within a particular tissue space or plane is determined by the size of the space involved. The relationship between the ejection pressure and the velocity of the stream of wax is governed by the equation. V=v'2gp/K (Gruner 1963) Where V----velocity in feet per second g=acceleration due to gravity, i.e. 32 ft./sec./sec. p--ejection pressure in lbs. per sq. in., and K--density of the injected material in lbs. per cu. ft. 69
High Pressure Injection Injuries, the Problems, Pathogenesis and Management--H. D. Kaulman
If for the purposes of the calculation we imagine that instead of wax, water was the material injected, then a range of velocities which might be encountered in industry could easily be calculated. Thus considering the grease gun operating at pressures up to 10,000 p.s.i. (10,000 x 144 lbs./sq, ft.) and water with a density of 6.24 x 10 lbs./cu, ft. V = / 2 x 32 x 104 x 144 = 1,360 ft./sec. / or 928 m.p.h. V' 6.24 x i0 Similarly the ejection velocity of the spray gun in use during the experiments would be calculated to be 332 ft./sec, i.e. approx. 225 m.p.h. As the specific gravity of the actual injected greases is not far removed from that of water (1.0) the velocities met with in practice would be of a similar order. Approximately one gram (0.036 oz.) of wax entered the finger at each shot, the limiting factors being the capacity of the finger and the fact that the digit is deflected out of the line of fire by the force of the stream. The palm usually corrtained about five grams of wax (0.18 oz.). The Kinetic energy which is dissipated on impact can be determined from the formula K.E.=½ mv 2, where m is the mass of wax ejected and v is the velocity of impact. Thus in the case of a finger injured by a stream of wax issuing at 10,000 p.s.i, the energy expended would be 2,040 ft. lbs. this value being approximately equivalent to a ton weight falling from a height of about ten inches. With a large amount of wax being considered as in the palm, then the figures would be correspondingly higher. Appreciating the magnitude of the forces the following was said by Golay and Verdan "I1 faut donc se m6fier de l'embout du graisseur, de l'injecteur du moteur Diesel, comme du canon d'un fusil charg6!" One should therefore mistrust the nozzle of the grease gun and fuel injector of the Diesel engine, like the barrel of a loaded gun (Golay and Verdan 1956). Some time ago Mason and Queen (1941) in their paper on the subject arbitrarily divided the local clinical symptoms and findings into three stages, v i z : - acute, intermediate and late. In spite of the elapse of almost thirty years this classification has not yet been bettered.
Acute Stage This represents the acute onset and immediate symptoms due to the entry into the tissues of a foreign material under high pressure. The initial swelling of the part is due to the introduction of the foreign material and the resultant inflammatory response with accompanying oedema. Following on the distention the tissues become white and anaesthetic and undoubtedly this is due to local interference with the vascular supply of the affected part. Many suggestions have been made as to the reason for the arterial insufficiency, but irrespective of the operating mechanism the resultant vascular changes impair the viability of the part. In addition the effects of the ensuing chemical inflammation and superimposed secondary infection cause tissue necrosis and contribute further towards gangrene. The sequence of events can b~e expressed diagrammatically as shown in Diagram 1.
Intermediate Stage This follows the acute phase and is characterised by the formation of oleogranulomata around the site of the injection. These oleomata are nodular tumours which arise as a result of a foreign body tissue reaction to the injected material (Fig. 10). They may remain without apparent change for many years but an associated fibrosis occurs which causes considerable loss of function and mobility of the affected part. 70
High Pressure Injection Injuries, the Problems, Pathogenesis and Management--H. D. Kau[man
Pallor
Numbness
',,
/
DIAGRAM 1 Intravascular Thrombosis
Destruction of vessels
Spasm of" vessels
Physical distention Injected material Chemi!al irritation
Circulatory Embarrassment
/
Acute Inflammation
~ Gang~rene
Pain
Secondary bacterial infection Sequence of vascular changes following high pressure injection injuries (Adapted from Smith, M. G. H., 1964)
Fig. 10
Histological appearance of oleogranuloma.
Late Stage
With the passage of time there occurs a breakdown of the skin over the oleomata, resulting in the formation of widespread cutaneous and subcutaneous lesions, ulcers and persistent sinuses occur which discharge an amorphous material consisting of grease and epithelial debris which is sterile on culture. The sinuses become secondarily infected and eventually the skin of the digit is much thickened and pitted, being both functionally and cosmetically poor. As a late complication malignant change may occur in the sinuses, the histology being squamous epithelioma (Vinogradov 1936). The intermediate and late stages can also be represented diagrammatically (Diagram 2). DIAGRAM 2 Chronic inflammation r-Fibrosis ~ Loss of function Chemical irritation
f
~ ' ~ Foreign body granuloma -- Sinuses ~ Malignancy Diagrammatic representation of intermediate and late stages (Adapted from Smith, M. G. H., 1964) 71
High Pressure Injection Injuries, the Problems, Pathogenesis and Management--It. D. Kaufman MANAGEMENT
Irrespective of the apparatus responsible for the injury the prognosis is poor and the morbidity considerable. It is convenient to consider the morbidity as that period elapsing from the time of the accident to complete healing and return to work. With all methods of treatment the morbidity resulting from forty injuries caused by all types of appliance, ranged from one month to two years. The so far accepted management of these injuries can be divided into: (a) conservative and/or local drainage of the affected area, (b) early amputation, usually because of gangrenous changes. On an average those patients treated by more conservative methods had a morbidity of about six months with a range of one month to two years, whilst the average time required for complete healing and return to work following early amputation was one and a half to two months. It has been demonstrated in the earlier part of this paper that following a high pressure injection injury the initial physical destruction is so great that a return to normality is precluded. This fact together with the lesser morbidity associated with radical surgery leads me to believe that the primary treatment for this condition should be immediate amputation of the affected digit. Naturally occasions will arise where this form of management is not acceptable e.g. thumb and palm, and in such circumstances wide exploration and evacuation of as much foreign material as possible is the treatment of choice, but skin grafting either immediately or later may be required. Should the synovial sheath of either the thumb or little finger be penetrated it is recommended that the radial or ulnar bursa respectively be irrigated with warm physiological saline to remove as much grease as possible. The cleaning of the sheath in this manner is purely mechanical and the use of chemical agents such as fat solvents is not advised. All surgical manoeuvres should be conducted in a bloodless field. Because compression of the part and further impregation of the tissues is likely to occur with the use of an Esmarch's bandage, this latter method of exsanguination should be avoided and instead the arm elevated for about 10 minutes before applying a tourniquet proximal to the site of the injury. In addition to the purely surgical aspect of the management, general therapeutic measures should also be used. Broadly speaking the latter fall into the use of three main groups of drugs.
Analgesics The injury both pre- and post-operatively is extremely painful, and in addition to morphia and pethidine, nerve blocks may be necessary. Local ring blocks should not be used as they will increase the local distension of the part, but on the other hand brachial plexus block is extremely effective in relieving pain. This method has been personally used with considerable success and does not appear to have been recorded previously.
Anti-In[ective Although even garage grease is sterile to culture, the prevention of secondary infection is important and the prophylactic administration of a broad spectrum antibiotic is suggested.
A nti-lnflammatory In an effort to minimise the considerable inflammatory response consequent upon the chemical irritation and secondary bacterial infection various drugs of this class have been used. Of these Tanderil (oxyphenbutazone--Geigy) was considered to be worthy of further trial. Bottoms (1962) using steroids (dexamethasone) claimed considerable success and recommended further usage of this class of drug. 72
High Pressure Injection Injuries, the Problems, Pathogenesis and Management--H. D. Kau[man GENERAL SUPPORTIVE MEASURES
Although systemic effects following injury have only been recorded on one occasion (Kaufman 1966), the increased use of high pressure spray guns for the delivery o f a variety of substances, many of which are toxic, would suggest that others will be encountered. The treatment is largely resuscitative and somewhat empirical, the clinical picture varying according to the toxic material absorbed. If severe toxaemia occurs urinary function should be observed to detect any signs of renal damage and similarly routine liver function tests would help detect any gross degree of liver damage that might be caused by substances such as industrial solvents. If intravenous therapy were required, five per cent dextrose and isotonic saline are adequate and should be administered according to the patient's fluid balance requirements and renal function. SUMMARY
A series of experiments were conducted to demonstrate the damage occurring following upon high pressure injection injuries. In addition to this an account of the clinical picture and prognosis was detailed, based on personal cases and a review of the literature. Finally the management of the condition was reviewed and in the light of the experimental evidence certain lines of treatment were suggested. ACKNOWLEDGEMENTS
The work in this paper formed the major part of the thesis for the degree of Ch.M. submitted to and accepted by the University of Liverpool. In addition it has to a large extent already been published in the British Journal of Surgery. Kaufman, 1966, 1968, a and b). Figs. 2 and 3 are reproduced through the generosity of the Editor and the Publishers of the British Journal of Surgery, John Wright and Sons Ltd., Bristol. REFERENCES BOTTOMS, R. W. A. (1962), A case of High Pressure Hydraulic Tool Injury to the Hand, its Treatment aided by Dexamethasone and a plea for a further trial of this substance. Medical Journal of Australia, 2: 591. GOLAY, L. and V E R D A N , C. (1956). Mortification tissulaire par jet de mazout. Zeitschrift ftir Unfallmedizin and Berufskankheiten. Revue des accidents du travail et des maladies professionelles, 49:115. G R O N E R , O. P. N. (1963). Sproyte- og Smorepistol skader. Skader ved hoytrykksprut fra sma apninger, oppstaelsesmate og behandling. Tidsskrift for den Norske Laegeforening, 83: 1263. K A U F M A N , H. D. (1966). A study of High Pressure Injection Injuries. Ch.M. Thesis, University of Liverpool. K A U F M A N , H. D. (1968) (a). The Clinicopathological Correlation of High-Pressure Injection Injuries. British Journal of Surgery, 55: 214. K A U F M A N , H. D. (1968) (b). The Anatomy of Experimentally Produced High-Pressure Injection Injuries of the Hand. British Journal of Surgery, 55: 340. K A U F M A N , H. D. and WILLIAMS, H. O. (1966). Systemic Absorption from High-Pressure Spray-Gun Injury. British Journal of Surgery, 53: 57. MASON, M. L. and QUEEN, F. B. (1941). Grease Gun Injuries to the Hand, Pathology and Treatment of Injuries (Oleomas) Following the Injection of Grease Under High Pressure. Quarterly Bulletin of Northwestern University Medical School, 15: 122. REES, C. E. (1937). Penetration of Tissue by Fuel Oil Under High Pressure from a Diesel Engine. Journal of the American Medical Association, 109: 866. SMITH, F. H. (1939). Penetration of Tissue by Grease Under Pressure of 7000 Pounds. Journal of the American Medical Association, 112: 907. SMITH, M. G. H. (1964). Grease Gun Injury. British Medical Journal, 2: 918. V I N O G R A D O V , I. (1936). Ober Sp~itfolgen Ktinstlicher Oleogranulome. Archiv ftir Klinische Chirurgie, 187: 69.
73