Penetrating high-velocity genitourinary injuries Part I. Statistics, mechanisms, and renal wounds

REVIEW ARTICLES

PENETRATING

HIGH-VELOCITY

GENITOURINARY

INJURIES*

Part I. Statistics, Mechanisms, STUART M. SELIKOWITZ,

and Renal Wounds

M.D.f

From the Department of Surgery, Division of Urology, Dartmouth Medical School, Dartmouth-Hitchcock Medical Center, Hanover, New Hampshire, and Veterans Administration Center, White River Junction, Vermont

ABSTRACT - As a consequence of missile-tissue energy exchange, high-velocity missile wounds necessitate wide surgical debridement because of severe tissue contusion distant from the wound tract. A missile tract mentally projected by the physician through the urologic tract demands appropriate investigation. The approach to urologic surgery may be primarily determined by the wound tract since this has to be debrided anyway. Ureteral filling on an intravenous pyelogram will save valuable time at surgery. High-velocity penetrating renal injury demands an aggressive surgical avvroach to obviate later comvlications.

A recent arms experts’ report from the International Committee of the Red Cross’ described “weapons that may cause unnecessary suffering or have indiscriminate effects.” High-velocity ammunition such as that used in our M-16 military rifles (5.56 mm.), the Russian and Chinese AK-47 (7.62 mm.), and many newer sporting arms are included in the definition from the report. The effect of these missiles is much like that of the “dum-dum” bullet, which was prohibited by the Hague Declaration of 1899. “Since high-velocity wounds seldom occur in peacetime,” relates the report, “most surgeons are unfamiliar with their specific treatment,” and the Surgeon Generals office concurs.’ However, high-velocity weapons are becoming more common in the continental United States and, in the current state of social and political unrest, it behooves the urologic surgeon to be familiar with their effects. *The opinions expressed in this article are the personal views of the author and in no way reflect the policies of the United States Army, the Veterans Administration, or the Dartmouth-Hitchcock Medical Center. t Former chief of urology and member combat surgical team, 12th Evacuation Hospital (USAMC), 3rd Corps, RSVN, 1967-1968.

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This article describes the experience garnered by the author from the treatment of 250 genitourinary wounds caused by high-velocity ammunition.3 This work is the compilation of an extensive, personal experience with urologic trauma under battlefield conditions at one of the most active Army treatment centers, the 12th Evacuation Hospital, in the war zone of the Republic of South Vietnam during 1967 and 1968. Because of the medical and military necessity for evacuation from the combat zone, there was little opportunity for patient follow-up beyond two weeks. Severely injured Vietnamese patients often were kept under surveillance for a longer period. Also, at the time of these injuries, the armed forces did not keep and categorize records of ultimate destination and final results concerning the wounded. Nevertheless, the author believes that the continuity of care under one urologic surgeon gives a unique and, hopefully, rare opportunity to study highvelocity penetrating wounds as they relate to the urinary tract. Statistics Marshall” reported less than 1 per cent incidence of urologic injuries in his series during

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World War II. Patton5 reported a 2 to 4 per cent incidence of genitourinary injuries during the same period. The Vietnamese experience6-8 resulted in a decrease from a 10 per cent incidence in the Busch et ~1.~ series to 3 per cent urologic injuries in this particular series. This reflects the type of warfare, the theater of operations, and the manner of documentation during a particular time. It may be inferred that the increasing incidence of shell fragments from 1965 to 1967,9 with the great number of boobytrapped, below-the-waist explosions prior to the Tet Offensive (1968), most likely accounts for the percentages of urologic injuries during the earlier phases of the Vietnamese War.

FIGURE 1. High-velocity missile wound resulting in bladder penetration and temporary cavitation effect with evisceration and bowel rupture.

FIGURE 2. (A) Highvelocity fragment wound to genitalia and inner thighs; (B) extensive debridement and orchiectomy necessitated by inM-5

FIGURE 3. (A) Throughand-through fragment wound to penis and thigh; catheter passed easily despite missile trajectory. (B) At debridement, missile tract passed between corpora cavernosa and urethra with minimal injury to both; instrument in tract

With the onset of more offensive type of warfare in 1967 and 1968, plus the use of highvelocity small arms, approximately 250 cases* of genitourinary injury were accounted for by this series. However, a concomitant increase in nonurologic wounds at the same time resulted in a reduction of urologic injuries to 3 per cent of the whole (8,511 total surgical procedures done at the 12th Evacuation Hospital from Sep*Recorded by author in the field since the Department of the Army did not break down surgical procedures by clinical service prior to 1971; many urologic wounds were multiple fragment wounds, laparotomies, and others.

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tember, 1967, to September, 1968). It is understood that 95 per cent of those patients with urologic wounds had associated injuries of other systems (that is, the multiplicity factor’,g) and some had more than one urologic injury. Also, not all of these wounds were of high-velocity origin although in this report we are primarily concerned with this type of injury. In the author’s experience, external genital injuries were less percentage-wise than in any of the other series except for World War I (Table I). This may be explained by less emphasis on booby-trap type of weapons and more of a shift to offensive small arms after 1967. The rate of

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TABLE I.

Site of Genitowinay

Znjuy (Adapted from Busch, et al.‘)

Per Cent of Injuries World War II Vietnam Gulp Kimbrough Selikowitz2g (1967- 1968) Busch (1965- 1966)

Site Kidney Ureter Pelvic injuries Bladder Urethra Penis Testicle and scrotum Total external genitalia

World War I Young

20.8 4.2

35 3

30.0 3.8

14.0 3.4

36.7 2.2

8.3 6.3 25.0 35.4 66.7

20 10 5 27 40

16.3 15.0 14.0 21.0 50.0

14.5 14.5 18.7 34.9 68.1

31.7 . . * . . .

genital injuries in World War I might be explained by the stagnant nature of the war with trench fighting and below-the-waist cover. These statistics also reveal that the pelvic injuries (arbitrarily, bladder and urethra in our series)3 rival those of World War II; that earlier in the Vietnamese War,6 pelvic injury was not so prevalent, again probably due to the nature of the war, lower velocity weapons, and the bony girdle protection afforded by the pelvis. Also, ureteral injuries have varied from their small incidence by only one or two percentage points, more or less, from war to war, and within the different series of the Vietnam War too.3 external

Ballistics A true appreciation of high-velocity projectile injuries can only be attained by some understanding of ballistics and how it relates to tissue damage. Low-velocity missiles, traveling less than 1,000 feet per second, will produce their major effect along the projectile’s tissue path, also called the “permanent cavity.“‘O However, high-velocity missiles, such as the M-16 bullet which has a muzzle velocity greater than 3,200 feet per second, cause most of their injury by the almost explosive consequences of what is called a “temporary cavity” produced by energy transference from missile to tissue. l1 The stability imparted by spinning a bullet in flight increases its impact velocity, range, and accuracy by reducing its aerodynamic resistance and, therefore, its tendency to tumble. However, the spin, itself, produces additional motions by a gyroscopic effect, not unlike that of a spinning top. These motions, known as precession and nutation, may be analyzed into a component known as yaw, which is a deviation of the missile’s longitudinal axis from the line of flight, the trajectory. The missile, under spinning conditions, is theoretically relatively stable

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unless the overturning moment increases so much that tumbling supervenes. It is of great importance that the energy liberated by a missile in tissue dramatically increases as the square of the velocity. The kinetic energy of a body of mass (m) and velocity (v) is described mathematically as E = mv*/2. This is the total energy given up if (v) represents the impact velocity and the missile is arrested in the target. However, if the missile emerges from the target, the energy (Et) liberated during the passage through the target is the energy (Er) at impact minus the residual energy (E2) of the missile at exit. This is represented as: Et=Ei--Ez=mv:

2

rnvg = m(v? - v.$ 2

2

Therefore, it can be appreciated that the energy (Er - E2) released, or given up, by a small missile determines the peripheral damage done and is dependent on the retardation the projectile undergoes which is related, in turn, to the tissue resistance, among other factors. The rate of change of velocity (deceleration), or the rate of retardation, can be expressed” as:

dv = (YVwherea = dt

DAcd 2m

Alpha (a) is the retardation coefficient, and it depends on the tissue density (D), the missile mass (m), the presenting area of the missile (A), and the drag coefficient (Cd). Put in another way, retardation rate of a missile, while penetrating tissue, is directly proportional to the impact velocity and tissue density. It can be seen from this that yaw, by presenting more missile area (A), will increase the discharge of energy to tissue. Tumbling of the missile will accentuate the process even more so. Considerable yaw occurs in tissue because the

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missile becomes unstable as it proceeds through tissues of various densities. Deformation of the missile and the motion of spin are modified by tissues of different densities causing the energy released to vary. Despite a reduction in velocity, the changes in motion and deformation of a missile as it passes through tissue actually increase its imparted exit energy. Therefore, the size of the exit wound is greater than the entrance in high-velocity missile injury. The principal method of damage by a lowvelocity missile is laceration and crushing along the permanent cavity. Shock waves occur as the tissue is compressed before the missile. Temporary cavitation occurs in high-velocity missile penetration as the tissue particles are accelerated and continue to move long after the missile has gone by. The cavity so produced may alternately be at pressures greater than 100 atmospheres and then subatmospheric as the cavity undulates and finally damps out.” While the temporary cavity is pulsating, air is alternately sucked in and out through both exit and entrance wounds. Critical temperatures are not high enough around wound edges to destroy bacteria that are sucked into these pulsating temporary cavities. l2 The damages caused by laceration and crushing and by shock waves are not nearly so important as the temporary cavity bruising that occurs. The energy exchange at high velocity can be so rapid that explosive wounding can occur. Nerve axon sheath and arterial disruption occur in high-velocity injury without actual penetration by the missile. The larger arteries, because of their elasticity, may not disrupt completely, but thrombosis can occur.13 Bone ends comminute as the pulsations are propagated and grind bone ends after the missile has passed on. Soft tissue, muscle for instance, is often severely contused a great distance from the permanent cavity. Temporary cavitation in the abdomen may cause bowel rupture through sudden enlargement of the intra-abdominal cavity (Fig. 1) and the expansion of bowel gases. It should be realized that high-velocity injury occurs not only with single bullet penetration but with some of the newer fragmentation shells that throw out pieces traveling over 4,500 feet per second. Because of their irregularity, the initial velocity rapidly drops off to below 2,000 feet per second within 30 feet. However, within that zone they are high velocity, and their injury potential will follow the previously discussed mechanisms.

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Debridement Mandatory adequate debridement,g the most important surgical point to remember about high-velocity missile injury, follows from what happens to tissue when pierced by a highvelocity fragment. Necrotic tissue, secondary to temporary cavitation, provides an excellent media for bacterial growth. Lack of adequate debridement leads to infection, sepsis, even gas gangrene, and secondary breakdown of wounds. Under an antibiotic umbrella, all fragment wounds, whether the entrance site is insignificant or not, should be laid open and liberally debrided along their tracts, taking care not to damage nerve and vascular structures even more (Fig. 2). In Vietnam, the wounded were covered with 20 to 40 million units of aqueous penicillin, 2 to 4 Gm. of streptomycin, or 1 to 2 Gm. of chloromycetin per twenty-four hours until after the delayed primary closure four to ten days later. If sepsis, foul smell, or drainage supervenes during this period, the wound is uncovered and immediately redebrided and not closed until clean for two to three days. At delayed primary closure, a layered closure of fascia, muscle, and subcutaneous tissue, without dead space or tension, is accomplished. Wound edges may be undercut subcutaneously to relieve tension. Skin flaps may be rotated to cover extensive areas of loss and a relaxing incision can sometimes be used. Skin grafts are applied to defects too large to close. Despite thousands of wounds closed in a delayed primary manner, the author remembers few which became grossly infected while the patients were hospitalized in the war zone. Obviously, many patients were evacuated almost immediately after closure and follow-up could not be continued. However, many others were returned to duty or kept beyond the usual time. Diagnosis and Evaluation Except for the external genitalia, the urologic organs are deep within the body, surrounded by a bony and muscular shield, so that highvelocity injury of one is usually associated with extensive wounds of contiguous structures. Single or multiple high-velocity wounds may involve every organ system. Both the multiplicity of abdominal wounds and the degree of shock correlate well with the severity of wounding.‘>g Often, the physical findings will lead one to suspect distant, intra-abdominal, chest, or extremity involvement. Roentgenograms of the

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projection of the missile path are necessary to note its presence, or air, at distant or crucial sites. Lateral as well as anteroposterior filins will fix the position of the fragments or missiles and aid in making a mental composite image of the line or flight through tissues. Usually, debridement and or repair are necessary at these sites and early organized planning will be to the patient’s advantage (Fig. 3). Of course, optimal conditions are not always available, especially in war. After stabilization with blood, intravenous fluids, chest tube, and so on, all these patients with any possibility of urologic injury received an infusion pyelogram, injected while in the emergency area, on the way to the radiology unit. Antegrade infusion pyelography” with 60 to 150 ml. of 50 per cent sodium diatrizoate given over a five to ten minute period will usually adequately visualize the upper tracts and the lower ureters in the majority of cases within fifteen to twenty minutes.r6 This one simple step greatly facilitated the workup and prevents back-tracking. Under the more sophisticated setting of a major civilian hospital, nephrotomography” and even arteriography’* can be done for a more accurate diagnosis of urologic and other injuries. Owing to the great number of penetrating wounds likely to occur under battlefield conditions and also to the stress of emergency surgery, ureteral injury can be overlooked. If, at surgery, there is a large pelvic and or retroperitoneal hematoma, the ureters may be difficult to find and examine, even with the bladder opened and the ureters catheterized. One would certainly rather not have to open the bladder unless absolutely necessary in an operative field that already may be contaminated from without and by bowel contents from within. Extensive dissection in a pelvic hematoma only adds blood loss and operating time to an already desperate situation, but should be done if one is unsure about urethral injury. Carlton, Scott, and Guthrielg report 91 per cent abnormal findings on intravenous pyelograms in patients with penetrating ureteral trauma. Therefore, immediate surgery is not the answer in most cases, and a preoperative intravenous pyelogram, if it reveals the necessary information on the ureters, is a valuable tool. *In patients with borderline shock and dehydration hyperosmotic solutions of radio-contrast should be administered with extreme caution because of the rapid vascular compartment fluid shifts, cerebral dehydration,14 and acute renal failure. I5

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Renal Injuries Our renal injury rate, 35 per cent (Table I), was the highest of all the wartime genitourinary series previously presented, except for World War I. This was due, perhaps, to the automatic weapons and fragmentation devices of offensive guerrilla warfare at close quarters. Our nephrectomy rate for penetrating wounds was approximately 84 per cent (74 of 88) which exceeds another earlier Vietnam military trauma series with a nephrectomy rate of 50.7 per cent (35 of 69)* and of renal injuries and civilian nephrectomy rates of about 27 per cent (38 of 139, 6 of 23)20*21and 18 per cent (11 of 60).” These figures include minor and major parenchymal and vascular injuries. Our statistics reflect a larger number of patients with high-velocity renal missile injuries reaching the hospital alive via rapid helicopter evacuation. One case sustained bilateral renal disruption, necessitating nephrectomies. He died of multiple injuries soon thereafter. Another patient was wounded in both kidneys necessitating a unilateral and spinal column, nephrectomy and a heminephrectomy on the opposite side and, much later, a hemicorpectomy. These cases constitute the second and third reported cases of bilateral penetrating renal parenchymal injury.24 There were no instances of high-velocity missiles causing thrombosis of the major renal arteries without frank vessel penetration. We did not practice conservative management of any penetrating renal wounds, highvelocity or not. All were explored primarily through a midline, abdominal incision. If there was evidence of missile perforation or hematoma in the retroperitoneum when the peritoneal cavity was opened for various reasons of multiple fragment or high-velocity missile wounding, a thorough exploration was done after first obtaining proximal renal vascular control. There are those who would explore such penetrating renal injuries.25,26 Since highvelocity missiles produce such a tremendous amount of renal damage, 27there was often no conceivable way of salvaging the kidneys, or because of multiplicity of wounds the surgeon often elected to save time, blood, and perhaps morbidity by performing a nephrectomy if the kidney was not seen to be easily repaired. It must be realized that some decisions were made on the basis of incoming casualties and the state of war the hospital, itself, was involved in at the time. Parenchymal wounds of the kidney were

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treated in a conventional manner, when possible, by debridement, drainage, partial nephrectomy, and others. There was a 16 per cent (14 of 88) incidence of partial nephrectomy, parenchymal or vascular repair and drainage. This is smaller than other civilian (72.7%[101 of 1391, 51.6% [31 of 60])20,22 and military (49.3% [34 of 691)s penetrating wound series. There is no way to know what might have happened had we left well-enough alone and not explored the retroperitoneum in some of the multi-fragment wounds of the kidney with relatively normal findings on intravenous pyelograms. However, the consequences of secondary renal bleeding or complications after a high-velocity missile injury could not have been easily tolerated, as in Ahoniemi, Fisher, and Rulfs’ case,27 under wartime conditions by many of the multi-wounded patients or by the overtaxed staff. We had no reason to regret this decision in the immediate postoperative period. Indeed, Cass and Ireland2* note that this course might lead to three times more renal removal, but less morbidity, and utilizing preliminary vascular control their nephrectomy rate approached renal loss with conservative therapy. We did not lose any patients because of a renal injury. We did not have any immediate complications of this type of treatment; most cases required debridement and exploration because of the high-velocity nature of their injury.

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9.

10. 11.

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14. 15.

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19.

Veterans Administration Center White River Junction, Vermont 05001

20.

ACKNOWLEDGMENT. Vietnam surgical totals courtesy of Col. B. E. Cooksley and LTC T. MacLeod; Patient Administration and Bio-Statistics Office, Department of the Army, Office of the Surgeon General of the United States.

21. 22.

References

24.

1. Weapons That May Cause Unnecessary Suffering or Have Indiscriminate Effects, Report On The Work of Experts, Geneva, International Committee of the Red Cross, 1973. Editorial report, The Boston Globe, SepASPIN, L.: tember 1, 1973. SELIKOWITZ, S. M.: Penetrating High-Velocity Genitourinary Injuries, Part 2, in press. MARSHALL, D. F.: Urogenital wounds in an evacuation hospital, J. Urol. 55: 119 (1946). Symposium of Treatment of Trauma PATTON, J. F.: in the Armed Forces, Army Medical Service Graduate School, 1952. 6. BUSCH, F. M., CHENAULT, 0. W., ZINNER, N. R., and CLARKE, B. G.: Urological aspects of Vietnam War injuries, J. Urol. 97: 763 (1967). 7. OCHSNER, T. J., BUSCH, F. M., and CLARKE, B.

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23.

25.

26.

27.

28.

29.

G.: Urogenital wounds in Vietnam, ibid. 101: 224 (1969). SALVATIERRA, R. O., RIDGON, W. O., NOREUS, D. M., and BRADY, T. W.: Vietnam experience with 252 urological war injuries, ibid. 101: 615 (1969). WHELEN, T. J., BURKHALTER, W. F., and GOMEZ, A.: Management of war wounds, in Welch, C. E., Ed.: Advances in Surgery, 3: 315 (1968). Chicago, Year Book Medical Publishers. HOPKINSON, D. A. W.: Firearm injuries, Br. J. Surg. 54: 344 (1967). AMATO, J. J., and RICH, N. M.: Temporary cavity effects in blood vessel injury by high-velocity missiles, J. Cardiovasc. Surg. 13: 147 (1972). THORESBY, F. P., and DARLOW, H. M.: The mechanisms of primary infections of bullet wounds, Br. J. Surg. 54: 359 (1967). RICH, N. M., AMATO, J. J., and BILLY, L. J.: Arterial thrombosis secondary to temporary cavitation, Surg. Digest 6: 12 (1971). RIESER, C. : Diagnostic evaluation of suspected genitourinary tract injury, J. A.M.A. 199: 124 (1967). DUDZINSKI, P. J., PETRONE, A. F., PERSOFF, M., and CALLAGHAN, E. E.: Acute renal failure following high-dose excretory urography in dehydrated patients, J. Urol. 106: 619 (1971). SMALLEY, R. H., and BANOWSKY, L. H. W.: Evaluation of renal trauma by infusion urography, ibid. 105: 620 (1971). MAHONEY, S. A., and PERSKY, L.: Intravenous drip nephrotomography as an adjunct in the evaluation of renal injury, ibid. 99: 513 (1968). LANG, E. K., et al. : Arteriographic assessment of injury from renal trauma, an analysis of 74 patients, ibid. 106: 1 (1971). CARLTON, C. E., SCOTT, R., JR., and GUTHFUE, A. G.: The initial management of ureteral injuries, Trans. Genito-Urin. Surg. 62: 141 (1970). SCOTT, R., JR., CARLTON, C. E., and GOLDMAN, M.: Penetrating injuries of the kidney, an analysis of 181 patients, J. Urol. 101: 247 (1969). WATERHOUSE, K., and GROSS, M.: Trauma to the genito-urinary tract, ibid. 101: 241 (1969). PETERSON, N. E., and KIRACOFE, L. H.: Renal trauma: when to operate, Urology 3: 537 (1974). amputation for adMILLER, T. R.: Translumbar vanced cancer, CA 19: 36 (1969). ESHO, J. O., and CASS, A. S.: Bilateral renal injury: case report, J. Urol. 108: 955 (1972). LUCEY, D. T., SMITH, M. J. V., and KOONTZ, W. W.: Modern trends in the management of urologic trauma, ibid. 107: 641 (1972). DEVILLAR, R. G., IRELAND, G. W., and CASS, A. S.: Management of renal injury in conjunction with the immediate surgical treatment of the acute severe trauma patient, ibid. 107: 208 (1972). AHONIEMI, P. J., FISHER, R. G., and RULFS, D. M.: Delayed multifocal intra-renal bleeding: a complication of high-velocity trauma, ibid. 110: 625 (1973). CASS, A. S., and IRELAND, G. W.: Comparision of the conservative and surgical management of the more severe degrees of renal trauma in multiple-injured patients, ibid. 109: 8 (1973). SELIKOWITZ, S. M.: The symphysiotomy approach to high-velocity missile trauma, Ann. Surg. 178: 616, 1973.

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