c:"'~- -- " ~ .,

,1:_,",Cl

(

Possible lndicatorsfor Antivenin Treatment

RALEIGH R. WHITE IV, M.O., and ROBERT A. WEBER, M.O.

Sixty-seven patients hospitalized for poisonous snakebite be-t\\'een 1975 and 1990 \\ere managed by elevation, tetanus pro-phylaxis, intra,'enous fluids and antibiotics, and often by a lim-ited excision ofthe bite site in the Emergency Department, "ithsequentiallaboratory studies as needed. Anti,'enin "'as used forsystemic em'enomation, and 23 of the 67 patients (34%) recened133 ,ials. Thirteen of the n\'enty-three patients (56%) had ad-verse reactions to the antnenin. T"o significant obsenationsarose. First age "as an indicator. Ele"en of eighteen patients 12years or younger (61 C;c) recei,ed antn'enin, ,vhereas 12 of 49patients older than 12 years (24C;c) recen'ed antn'enin (p = 0.0085,

Fisher's exact test). Second species of snake '\as an indicator.Sixty-nvo snakes "ere identified (93%). Of 39 rattlesnake (Cro-talus and Sistrurus) bifes, 20 patients retened antn'enin (53%),but of 23 copperhead and \\ater moccasin (Agkistrodon) bifes,only three patients(12.5%) received antn'enin (p = 0.0025). An-

tn'enin mar be indicated for use in systemic rattlesnake emen-omation, especially in younger patients.

From the Department o, Surgery, Texas A&M UniversityCollege o, Medicine, Scott and White Clinic

and Hospital, Temple, Texas

poisonous snakebites, Iooking especially for possible in.dicators to administer antivenin.

Methods

T HE CLlNICAL MANAGEMENT of poisonous snake-bite continues to stir controversy. Advocatesof antivenin (Crotalidae) polyvalent therapy

(Wyeth-Ayerst Laboratories, Philadelphia, FA) recorditsbenefits and suggest the potentially harmful result of ag-gressive surgical treatment.I.2 Others eschew antivenin torecommend excisional therapy,3 and so me favor excisionjfasciotomy therapv,4.5 sometimes using antivenin. Re--cently a majar series report suggests that neither antiveninnor surgical excision is needed in the majority of snakebitecases.6

Stimulated by the controversy, we established a 15-yearinstitutional review to assess our experience in treating

Presentedat the 102nd Annual Scientitic Session ofthe Southern Sur-gical Association, Boca Raton, Florida, December 3-6, 1990,

Address reprint requests to Dr, Raleigh R, White, Department ofSur-

gery, Texas A&M Uni\ersity ColJege ofMediqine, &ott andWhiteOinicand Hospital. 2401 South 31st Street, Temple, TX 76508.

Accepted for publication Janua~ 9, 1991.

From 1975 through January 1990, 67 patients wereadmitted for treatment of poisonous snakebite at Scottand White Hospital, Texas A&M University College ofMedicine in Temple, Texas. Patient ages ranged from 1to 76 years. Nine patients were aged 6 years or younger.and 18 were 12 years or younger. The average age was32.5 years. Forty-eight patients were male, and 19 patientswere female. The average time from injury to hospitalpresentation was 1.9 hours, with a range of la minutesto 12 hours.

The biting snake was identified in 9390 of the cases.Either the victim or an observer at the scene made positiveidentification or the snake was identified using a coloratlas at the Emergency Department. All snakes identifiedwere native to Central Texas, where 11 species ofpoison-ous snakes are indigenous, including the western dia-mondback (Crota/us atrox), the canebrake rattlesnake(Crota/us horridus atricaudalus), the timber rattlesnake(Crota/us horridus horridus), northern blacktailed rattle-snake (Crolalus m%sus molo5'u5), and the prairie rattle-snake (Crolalus viridus viridus). A second genus ofCentralTexas rattlesnake includes the western massasauga (Sis-trums catenatus lergeminius), the western pigmy (Si5'lrn-rus miliarius slreckeri), and the desert massasauga (.S'i.\-lrurus ca.lenatus edwardsi).7

A third genus of poisonous snakes native to CentralTexas includes the broad-banded copperhead (AgkiSlro-

466

"-""'~ .,-." , -"CC-, ""'C"",?:,,,,, 'C'io,.

ii~4~

Vol.213.No.S POISONOUS SNAKEBITE IN CENTRAL TEXAS 467

mer, and the right hand (27) and left foot (21) were themost common bite sites.

Initiallaboratol)' studies included complete blood countwith platelet count and clotting studies (prothrombin time,partial thromboplastin time, fibrinogen levels. and fibrinsplit products.) These studies were repeated at 6-hour in-tervals until stable. Initial treatment often included a lim-ited, early excision of the bite wound, especially for rat-tlesnake bites. Removal of a small 'plug' of skin and sub-cutaneous tissue, to include the fang marks, was chosenwhen anatomically convenient. Sometimes an incisionwas made connecting two fang marks. This procedureusually was carried out in the emergency department.Fascial integrity can be assessed through this wound.

The small wounds resulting from bite excision some-times produced voluminous outpouring ofserous drainagein the first several days, thU':s partially decompressing the

extremity.Wound sites were maximally elevated to protect distal

tissue from vascular compromise associated \v1th swelling.Upper-extremity bites were elevated by nonconstrictingstockinette sling, and lower extremity hiles were elevatedwith multiple pillows and bed positioning. Swelling wascentripetal, and regionallymph nades routinely becametender. Swelling and ecchymosis often progressed to thetrunk.

Patients were administered intravenous fluids and an-tibiotics, tetanus toxoid, and analgesics as needed. In theearly years ofthe review, four patients were administeredsystemic steroids. On review no specific benefit could beattributed to steroid therapy. Patient condition was mon-itored continuously. If severe systemic symptoms devel-oped, such as marked nausea and vomiting, central ner-vous system signs, cardiovascular shock, or deteriorationof clotting parameters, the patient was skin tested for sen-sitivity to antivenin (Crotalidae) polyvalent. Ifnonreactiveto skin test, patients with severe systemic signs and symp-toms were moved to a monitored bed in the surgical in-tensive care unit and administered intravenous antivenin.If no allergic symptoms developed, multiple vials wereadministered according to package insert guidelines (Table1). Twenty-three patients received 133 vials. Mild itching

don contortrix laticint/ls), the southern copperhead (Ag-kistrodon contortri.\' contortrix), and the western cotton-mouth moccasin (Agkistrodon piscn'oms le/lcostoma).7

According to type of snake, 39 victims were bitten byrattlesnake (58%), 20 by copperhead (30%), 3 by cotton-mouth moccasin (4%), and 5 by an unidentified snake(7%). Medical record review also included location ofbitewound, circumstances ofthe biting event, patients' clinicalsigns and symptoms, steps in early management, labo-ratory reports, severity of injury with attempts at retro-spective grading of envenomation, use of antivenin, re-quirements for further surgery, and eventual outcome.

Results

lnitial care began with verification of bite wound bypoisonous snake. Some patients brought to the EmergencyDepartment a dead snake in a bag, and one even broughta live one. The history of snakebite was then confirmedby documentation of one or more fang marks at the bitesite. The distance between fang marks was used as a guideto size of snake and gave rough indication of severity ofenvenomation to be expected. Physical findings and com-plaints of pain confirmed envenomation, but severity ofthese signs varied widely at the time ofinitial presentationto the emergency department, depending partially onelapsed time since the biting. The sooner the patient carneto the emergency department, the more unimpressive werethe presenting physical findings. Several patients thoughtinitially to have sustained no envenomation, but who hada positive history and fang marks, subsequently, in theensuing hours developed pain, marked swelling, and ec-chymosis. All patients with fang marks were admitted forclose observation because initial grading was unreliableas a guide to the severity of envenomation. Clinical signsand symptoms evolved progressively in 6 to 12 hours afterbiting, revealing the degree of envenomation. Subsequentretrospective grading also pro ved imprecise.

No patients were bitten on the job, but all were bittenduring what generally could be termed recreation-suchas hunting, fishing, gardening, outside play, and snakeround-ups. Most bites occurred during spring and sum-

T ABLE l. Guidelines for Antivenin Admini.!"tration

Amount of AntiveninManifestationsSeverity

o2-4 vials5-9 vials10-15+ vials

No envenomationMínima] envenomationModerate envenomationSevere envenomatíon

:--'0 local or systemic signsLocal swelling, no systemic signs, normallabExtended swelling, 1 or more systemic manifestation, lab abnormaJitiesMarked local response, severe systemic manifestations

From Wyeth, Antivenin (Crotalidaej PolyvaJent (equine origin) package insert, 1984.

468 WHITE ANO WEBER

In.

Surg .May 1991

"ABLE

¡"/lriher

erJ

Del!

PatientsRecei\ingFunherSurgef)'

,

of PatientsReceivingFUI1herSurgery

Rattlesnake bitesCooperhead bitesWater moccasin bitesUnidentified12 years old or youngerOlder than 12 years oldTotal patients

16 (411 (5",2 (67O9 (50'

10(~0'19 (~8'

2011

O4753

]00

51849

received antivenin (p = 0.0085). Of the 12 patients de-

veloping severe coagulopathy, 9 were children, whereasonly 3 were adults (p = 0.0002).

Adverse reactions to antivenin \Vere recorded in 13 of23 hospitalized patients treated with antivenin (56%). Nineof these patients had seyere anaphylactic reactions withshock symptoms. This experience leads us to give anti-veniD in the intensive caTe setting. The mea n age of hos-

pitalized patients showing no adverse allergic reactions toantivenin was 18.2 years, \vhereas those with adverse al-lergic reactions had a mean age of 34.5 years. Althoughyounger patients were sicker and more often received an-tivenin, they tolerated anti\'enin therapy better, havingfewer adverse reactions. The frequency of serious allergic

reactions, however, is a majar restraint on OUT decisionto chose antivenin therapy.

During the hospital course, 19 patients required sub-sequent surgical procedures (Table 3). Of these, 16 ",'ererattlesnake bite victims (84%), 2 were moccasin bites, and1 was a copperhead bite. Rattlesnake bites (16/39) weremuch more likely than copperhead bites (1/20) to requirefurther surgery (p = 0.005). A 7-year-old patient, who wasbitten by a copperhead on the left fifth toe. developedsevere nausea and vomiting and a marked coagulopathyassociated with dramatic swelling and impaired circulationin the left foot. Within the first 24 hours he had a pressure-

releasing dorsal skin incision that was closed secondarilyon day 6. No tissue was lost. This patient, treated in 1980,was also OUT last copperhead bite to receive antivenin.One of the two moccasin bite victims was similarly op-erated for severe lower-extremity swelling and distal isch-emia with secondary closure and no tissue loss. The othermoccasin bite requiring further surgery had a left longfinger bite that led to finger-tip necrosis and distal inter-

phalangeal amputation. The 16 rattlesnake patients re-quiring additional surgery included two arthrotomies forwash-out of joint penetration (one finger in an adult andone knee in a child). Fasciotomy was used whenever sus-

or hives were treated with intravenous Benadf)'i1Si (Parke-Davis, Morris Plains, NJ). When severe allergic reactionssuch as anaphylactic shock developed, however, the an-tivenin was immediately stopped and the patient was re-suscitated.

Clotting abnormalities seemed to be of two varieties.One was a consumption-type coagulopathy with very lowplatelet count and disseminated intravascular coagulation.The other was a heparinlike syndrome with prolongationofprothrombin time and partial thromboplastin time butwith normal platelet count. Mixed-cQagulopathy patternsalso were noted. Both types of coagulation abnormalitiesoccasionally returned toward normal within minutes ofintravenous antivenin administration, but not in all pa-tients. Some antivenin recipients demonstrated slow re-covery of clotting aberrations in a way similar to untreatedpatients. Relief of gastrointestinal symptoms frequentlyfollowed antivenin administration, but again, at a variablerateo

Of the 67 patients hospitalized, 23 were treated withantivenin for severe systemic symptoms of envenomation(Table 2). Twenty of these twenty-three severely injuredpatients (87o/c) were rattlesnake (Crotalus and Sistrnrns)bite victims, constituting 53% of the 39 total rattlesnakebites. The remaining three patients treated with antiveninfor severe systemic symptoms were bitten by copperhead(two) and cottonmouth moccasin (one) of genus Agkis-trodon. They constituted 13% ofthe 23 Agkistrodon bites.Comparing species ofbiting snake as an indicator for an-tivenin use, 53,:,c of Crotalus and Sistrnrus hiles weretreated, but only 13% of Agkistrodon hiles were treated(p = 0.003 Fisher's exact test). AII thtee of these Agkis- '.

trodon hiles were treated before 1980. OUT current practiceis to withhold antivenin for Agkistrodon bites because thesymptoms are less severe and resol ve sooner than do rat-tlesnake bite symptoms.

Analysis of patient ages (Table 2) showed that 18 bitevictims were 12 years of age or younger and that 11 ofthese (61 %) recei ved anti veniD for signs of systemic en-venomation. By contrast, 12 (24%) of49 older patients

'ABlE;

Palien! Groups

Ratt.lesnake hilesCopperhead bi!esWater moccasin bitesUnidentilied] 2 years old or younglOlder than 12 years 01T ota! patients

392035

184967

2010

o1112

23

61

2434

~

POISONOUS SNAKEBITE IN CENTRAL TEXAS 469

bite patients stayed 2 days or less in the hospital and clearlyhad minimal envenomation.

Discussion

picion of subfascial envenomation led to concern formuscular compartment pressure syndrome.

One rattlesnake victim kept several 'pet' snakes in hishouse and regularly 'mainlined' small doses of venomintravenously in the mistaken effort to become tolerant.He was 'kissing' a large rattler when it bit him in theupper lip, causing marked facial swelling. Surgical releasewas performed by upper labial sulcus incision for sub-muscular elevation of the soft tissues of the central faceat the periosteal level, resulting in outpouring of edemafluido Eventual healing ensued with no tissue loss and nopostoperative complications. A 55-year-old man, bittenon the left foot by a rattlesnake, was treated with ice beforereferral to Scott and White and sustained eventual ski nnecrosis on the foot and ankle. He had a $urgically re-mediable arterial occlusive lesion that was repaired beforesoft-tissue reconstruction. The left foot wound was re-paired, first by unsuccessful free flap transfer, and latersuccessfully by cross-leg flap. Limb salvage was accom-plished, but ibis patient was in the hospital for 57 days.One female competitor in the snake-bagging contest at arattlesnake roundup was struck by a large rattlesnake that'hung on' for a prolonged intervalo Despite antivenin andsurgical releasing incisions, marked tissue necrosis led toamputation ofthe index finger rayo Nine ofthe nineteenpatients requiring subsequent surgery were a~ed 12 yearsor younger, arate of 50% for the 18 children in the series(Table 3). Ten offorty-nine older patients (20%) requiredfurther surgery (p = 0.03). No patients died.

Average length ofhospital stay (Table 4) for all patientswas 5.6 days. Rattlesnake bite victims stayed an averageof 7.8 days, whereas copperhead bite patients averaged2.2 days. The three moccasin bite patients stayed 11, 5,and I days in the hospital. Using hospital stayas a severityindex, rattlesnake bites kept patients in the hospital thelongest. Further only two of the 20 copperhead bite pa-tients stayed longer iban 4 days in the hospital (6 daysand 8 days), whereas nine of 39 rattlesnake bites stayedin the hospital ayer 10 days (10, 13, 14, 15, 17, 19, 19,20, and 57 days). At the same time, 12 of39rattlesnake

T ABLE 4. Lenglh af H, o.\pitalSlay

Number ofPatients in2 or Less

Days

Although ibis series of 67 poisonous snakebites is nota large experience, it demonstrates several observationsthat may help us to understand some of the divergent

recommendations in the snakebite literature.First OUT study suggests that all United States pit vipers

(Crolalid family), and pit viper hiles, are not equal. OUTrattlesnake (Crolalus and Sislnlrns) bite patients moreoften manifested signs of sev~re envenomation. more of-ten required additional surgei-y, more often received an-tivenin, and had a much longer average hospital stay ibanthe copperhead (Agkislrodon) bite patients. Of coursesome rattlesnake hiles produced minimalenvenomation,but if a large rattlesnake inflicted significant envenoma-tion, the patient would very likely be quite sick.

Snakebite series wherein rattlesnakes (Crolahis and

Sislrurns) predominate, such as the comprehensive reportsofSnyder et al.,8 Glass,4 and Grace and Omer,5 documentthe severe injury caused by significant rattlesnake enven-

omation, including tissue necrosis, amputation, and death.Our rattlesnake experience supports these reports.

Other authors report snakebite series predominantlyinvolving bites by copperhead and water moccasin (Ag-kislrodon),6,9 or the mildly poisonous Northem Pacificrattlesnake (Crolalus viridis oregansus).2 Burch et al.6 re-port a larger series of 81 snakebites, but only la wererattlesnake hiles. These la hiles accounted for four oftheir five most severe envenomations. Their 45 copper-head bite patients had a relatively short hospital stay (2.5

days), comparing favorably with OUT average copperheadbite hospital stay of 2.2 days. Similarly a recent report byWagner and Golladay9 suggests management guidelinesfor (Crolalid) envenomation in a series of 29 young snak-ebite patients that included only three documented rat-tlesnake hiles. Of the 26 remaining hiles (Agkislrodon orunidentified), al! but one wasjudged to be mildly or min-imally envenomated. Only three hiles were graded moresevere-two rattlesnake and one moccasin. In OUT seriesthe 20 copperhead hiles were similarly less severely en-venomated than the 39 rattlesnake hiles.

Based on our experience and that reported by others,we believe that identifying the biting snake is an importantaspect in establishing the therapeutic mind-set for the caTeof a snakebite patient. In doing so, some apparent con-tradictions in management recommendations are re-solved. Burch et al.6 and Wagner and Golladay9 reportseries from OUT south-central United States region. Theirseries include few ratt]esnake hiles, and their recommen-

AverageDays inHospitalPatient Groups

39 Rattlesnake biles20 Copperhead biles3 Water moccasin5 Unidentilied

67 Total patients

9,(2f\

7.82.2~ 7

12 (32o/c

16 (80o/cI (33o/c5 (IDO'

470 WHrTE AND WEBER

dations for therapy are conservative, mostly advocatingsupportive careo Looking exclusively at OUT copperheadbite patients, we concur with these authors. We disagree,however, that management experience based largely oncopperhead bites should be generalized to the manage-ment of all Crolalid (United States pit viper) bites.

Similarly when Snyder et al.,8 Glass,4 and Grace andOmer ,5 all dealing mainly with rattlesnake victims, ad-vocate more aggressive medical and surgical treatment,we again concur. OUT significantly envenomated rattle-snake bite patients suffered severe pain, marked coagu-lation defects, systemic symptoms, and tissue necrosis.We agree that aggressive medical and surgical therapy isappropriate for many rattlesnake bite victims, but we dis-agree that one can generalize from this experience tomanagement recommendations for all 'Crolalid (US pitviper) bite patients. We also disagree with the influentialreport of Huang et al.3 from a coastal Texas experiencegeographically similar to that of Burch et al.6 Huang ad-vocated an aggressive surgical excision approach to allpoisonous snakebite patients without any genus identifi-cation ofbiting snake in the reporto OUT data cannot sup-port the implicit assumption that all poisonous snakebitesare the same and should therefore be treated similarly. Ingeneral rattlesnake bites are worse injuries than copper-head bite s, and cottonmouth moccasin bites probably fallsomewhere in between.

Secondly, OUT data show that younger patients sufferedmore se,ere envenomation syndromes than did adults.This observation is consistent with other reports.5.8 Onthe other hand, Wagner and Golladay9 suggest that poi-sonous snakebite in children can be managed conserva-tively, especially in copperhead bites. In addition, our.datashow that 9 of 12 severe coagulopathy reactions occurredin children, one of which was a copperhead bite. Whetherthis age group difference is related to weight, blood vol-ume, surface afea, ór other factors is unknown.

Biochemical analyses of snakebite-related coagulationdefectslO-13 suggest significant species differences amongpoisonous snakes. Not only are differences noted betweenEastern diamondback rattlesnake (Crolalus adamanleus),which can cause a hypofibrinogenemia without profoundthrombocy10penia,13.14 and Western diamiondback (Cro-lalus alrox), which can cause a consumptive-type coag-ulopathy with thrombocytopenia,12,15 but also differencesare noted among individual snakes in the same genus.11,12There is e,en variation ofvenom enzymatic content doc-umented in the same rattlesnake at different times.15Moreover distinct differences between CrOlalus and Ag-kislrodon venoms are noted both in their mechanism ofenzymatic initiation of anticoagulation effect and in theirpotency to anticoagulate the victims.13

Ann Sur¡. May 1991

.lndications for antivenin treatment remain uncertainand subject to debate. Analysis of our data shows thatrattlesnake (Crotalus and Sistrnrns) bites andjuvenile pa-tient age are two factors that correlate both with increasedseverity of envenomation and consequently with our se-lective decision to administer intravenous antivenin.

The answer to the question of when to give antiveninis not clarified by inspection ofthe antivenin (Crotalidae)polyvalent. lt is developed by collecting concentratedserum globulins from horses immunized with the follow-ing venoms: Crotalus adamanteus (Eastern diamondbackrattlesnake), Crotalus atro.x (Western diamondback rat-tlesnake), Crotalus durissus terrijicus (Tropical rattle-snake, Cascabel) and Bothrops atrox (Fer-de-Iance).16 Thedecision to treat with antivenin not only loads the patientwith additional foreign animal proteins but also admin-isters a product derived from equine exposure to snakevenoms, two of four of which snakes do not even residein the United States. Knowing the variations among nativesnake venoms, one must question the wisdom of givingpatients antivenin against foreign snakes. The content ofantivenin complicates a therapeutic decision already fac-ing myriad variables. ,

Until the double-blind study called for by Lindseyl7 ispublished, the treating physician must weigh indicationsfor antivenin therapy on an individual basis.

We recommend withholding antivenin therapy forcopperhead snakebite patients in all but the most severecopperhead envenomations. Rattlesnake hiles in our 10-cale are capable of producing very severe envenomationsyndromes, especially in young patients, and, therefore,we will continue to treat selected severely envenomatedrattlesnake bite victims with antivenin. The species ofsnake and the age of patient may be possible indicatorsfor its selected use.1~~=G¡a~~ur treatment recommendati~s:we ad-

vocate earlv limiten hite Pyric;ioQ when anatomically con-

venient, following Snyder et al.,8 who demonstrated re-

Il1o~al.of ~ t2 75J°.of ~nje~te~ "e.no¡J1 f;¿r ~p.t°.2 h.ou~.after the bite. We especially advocate excision of rattle-.,. ...snaKe and cottonmouth moccasin bites. T~e inillTPn n~rtis the~ elev~ted t.o rni.nil1Jiz~ swellinli' ~eeking to avoid

releasing incision/fasciotomy. toagulation studies and~!inical conniti~n ~rp ~nnitArp;¡- Surgical releasing inci-

slons are used for any signs of circulatory compromise inperipheral tissues or to release envenomated muscularcompartments. No attempt is made to excise ecchymotictissue at the time ofthese later operations.Secondarv clo-C;llre ic; c;mloht ~c; c;onn ~c; nprrp~c;en ~wpl1ino ~llnwc;. lntra-venous antivenin (rrntalidae) Dolvvalent i~ Qiven 10 n~-tients who manifest svstemic ~iQn~ nf c;pvprp pnvpnArn,,-~, mostly for rattlesnake bites, especi~ i-;;-childre;

'11¡.j ,

~

llol:!13.No.5 POISONOUS SNAKEBITE IN CENTRAL TEXAS 471

8. Snyder CC, Pickins JE. Knowles RP. et al. A definiti\'e study ofsnakebite. J Aa Med Assoc 1968: 55:330-337.

9. Wagner CW, Golladay ES. Crotolidenvenomation in children: se-lective conservative management. j Pediatr Surg 1989: 24: 1 28-131.

10. Simon TL. Grace TG. Envenomation coagulopathy in wounds frompit vipers. N Eng J Med 1981: 305:443-447.

11. Hasiba U, Rosenback LM. Rockwell D. Lewis JH. DIC-like syn-drome after envenomation by the snake, Crotahls horridus hor-ridus. N Eng J Med 1975: 292:505-507.

12. Budzynski AZ, Pandya BV, Rubin RN, et al. FiblÍnolytic afibri-nogenemia after envenomation by Western diamondback rattle-snake (Cmtohls otro.\"). Blood 1984: 63:1-14.

13. Van Mierop LHS, Kitchens CS. DefiblÍnation syndrome follo\\'ingbites by Eastern diamondback rattlesnake. J Aa Med Assoc 1970;67:21-27.

14. McCreary T, Wurzel H. Poisonous snakebites: report ora case. JAMA1959; 170:268-272.

15. Reid HA, Theakston RDG. Changes in coagulation effects by venomsof Crotolus otrox as snakes age. Am J Trop Med Hyg 1978; 27;1053-1057.

16. Olin BR, Hebel FK, Connell SI, et al. Facts and CompalÍsons. StoLouis: JB Lippincott. 1990, pp 451-45Ia.

17. Lindsey D. Controversy in snake bité-time for a controlled ap-praisal. J Trauma 1985; 25:462-463.

IFurther surgef)' is chosen as needed in the repair of ne-i'rotic tissues. This occurs predominantly in rattlesnakebites.

References

l. Russell FE. Ruzic N. Gonzales H. Effectiveness of Antivenin (Cro-lalidac) poly\alent follo\\'ing injection of Crolalus venom. T ox-icon 1973.11:461-464.

2. Butner AN. Rattlesnake bifes in noI1hem C.alifomia. West J Med1983; 139: 179-183.

3. Huang TT. Lynch JB. Larson DL, Lewis SR. The use of excisionaltherapy in management of snakebite. Ann Surg 1974; 179:598-606.

4. Glass TG Jr. Early debridement in pit viper bit es. JAMA 1976: 235:2513-2516.

5. Grace TG, Omer GE. The management ofupper extremity pit viperwounds. J Hand Surg 1980: 5:168-177.

6. Burch JM. Argaf"\\al R, Mattox KL, et al. The treatment of Crolalidenvenomation without antivenin. J Trauma 1988; 28:35-43.

7. Russell FE. Snake Venom Poisoning. Philadelphia: JB Lippincott.1980, pp 57-65.

ofthis organization, feels as 1 do, that if adequate antivenin is given onerarely needs surgery.

Because 21 % of alI snakebites occur in the digits, we have done 80digit derrnotomies and think it is helpful and have described this pro-cedure in the literature.

Dr. White, I'd liketo ask you how many ofyour cases with antiveninhad severe anaphylaxis. 1 agree a double-blind study would cenainly bein order, as you mentioned.

DR. RICHARD BAKER (Lubbock, Texas): At Texas Tech we see lO to15 bifes ayear, exclusively the Western diamondback or the prairie rattler.

OUT current management is immediate exploration and decompressionbecause in the past approximately one quarter of OUT patients requiredsubsequent decompression after antivenin treatment, which was consid-ered a failure.

This slide shows an II-year-old who had received eight vials ofantiv-enin in another institution,came in with a cold, insensate leg and requiredex ten si ve debridement, which we closed a week Jater. And the child,again, has no significant disability.

1 do not know an end point for the use of antivenin. One of OUTemergency room physicians regionally uses 100 to ] 25 vial s of antiveninfor significant envenomation. That's $10,000 to $]2,000, which 1 findintriguing, to say the least.

I would ask Dr. Whitc, if you do decide to use the antivenin, what's

~'our cnd point?

DR. TIM PEN:-JELL (Winston-Salem, Nol1h Carolina): Drs. White and\..'eber have undel1aken another good approach in attempting to answerthe very fundamental yet frustrating question ofwhen to use antivenin.It remains a controversial issue, as we have leamed in this discussion,and indeed indicators are needed. The authors make three very goodpoints in their manuscript. (1) Antivenin is not a benign mode of treat-mento (2) AII poisonous snakes and snake bites, even occurring in thesame genus, are not equal. Incidentally those of us who are confrontedwith managing such injuries should be mindful that 20% ofall pit viper

DISCUSSIONS

DR. CHARLES H. \'ATT, JR. (Thomasville, Georgia): 1 became in ter-ested in the treatment ofsnakebites 37 years ago when Dr. L. M. Kiauberof San Diego in his classic two-volume series of rattlesnakes stated thatthe Eastern diamondback rattlesnake was probably the most dangerousin America.

We have 272 poisonous snakebites treated since 1953; 94, as you see,were caused by the Eastern diamondback. Most of our bites were fromthis species and the FJorida couonmouth. There were no deaths. Therewere no deforrnities. except in one case in which cryotherapy was usedat another institution.

Two reasons, perhaps, account for the difference in our treatment.Dr. White is faceA1 \..ith a 2-hour presentation time, as you noted a minuteago, compared to OUT 40 minutes. The difference in species, as he noted,must be taken also into account, which may be why we areusingantiveninmuch more frequently and in Jarger amounts in treating our Easterndiamondback and canebrake ratt]esnakes.

We areacutely a\..'are ofthe disadvantages ofhorse serum in antiveninalso, but without antivenin, we would ha ve several deaths-which hap-pened in our hospital before 1953, but not in our series.

Even with a negative horse serum test, we administer epinephrine andantihistamine, which reduces considerably the incidence of anaphylaxis,and the frequent occurrence ofserum sickness is controlled with steroidsand an antihistamine.

In severe cases we mav give antivenin as a 5-minute push, but werarely continue the push ~fter the first few vials, then switch to a moredilute solution. Due to the above routine, we almost never see coagu-lopathy. We average 18.7 vials of antivenin per patient who has beenbitten by the Eastern diamondback and canebrake rattlesnakes. We givean average of 9,2 vials of antivenin to the victims of the adult cotton-mouth.

1 don't know whether that shows up very well, but this is a goodexample of a child biuen on the left leg three times by an Eastern dia-mondback snake with no excision and who received 22 vials ofantivenin.She had no deformit~,

We have had to do only one fasciotorny in this series of 272 cases.This followed cf)otherapy in another hospital, even though adequateantivenin had been gi\en. Bill Lorimer ofFt. Worth, Texas, and a member

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472 WHITE AND WEBER

bitesdo not result in any envenomation. (3) The use ofantivenin shouldbe based on the degree of systemic envenomation and as presented,predictors ofthis are age and size ofthe patient and snake type and size.Of course the unknown factor is the dose or amount of venom that isinjected and this can be measured accurately only on the basis of clinicalresponse. Funhermore one must take into consideration the basic healthstatus ofthe victim in connection with these other factors.

Ifwe combine and compare this series with ours reponed in 1986 andnow conujning 119 patients, the distribution oftype ofsnake and resultsremain the same. OUT series is dominated by copperhead bites. whereasthe Scott-White clinic experience is predominated by rattlesnakes. Theyare faced ~ith the famous rattlesnake round-up in their afea. Even withthis variation. we both are stressing that copperhead and cottonmouthbites, even ~ith envenomation, rarely if ever require the use of antivenin.

One final point, which is often overIooked. and then a question. Theperson who susujns a poisonous snake bite either because ofwhere theylive, their vocation, or hobbies and outdoor activities. usually retums tothe same or similar locations. They are, therefore. at increased risk forsubsequent snake bites. We should not sensitize these people with theinappropriate use of horse serum-based antivenin. 1 would be most in-terested if any ofthe patients in this series sustained more than one snakebite or strike on different occasions.

Ann Sur¡.. May 1991

only with severe systemic illness but would also be justified in thosepatients who had severe envenomation but no severe systemic illness.That is, a patient such as the one who has extremity injury or enven-omation with massive swelling but no systemic signs. Furtherrnore it issuggested by this data that presen'ation of muscle function can be achievedby the administration of antivenin alone.

.So the question would be then, first. do the authors feel that the ad-ministration of antivenin may result in presen'ation of muscle functionand, therefore, would be justified in that special circumstance?

I am also interested in the fact that the rate of anaphylaxis was sohigh. In point offact, an anaphylaxis rate in excess of 40% is much higherthan that reported by other authors who cite rates of 1 % to 10%. Is therea reason for this? Is the rate changing in the more recent time interval?

I applaud the authors' use of consen'ative therapy and antivenin andthe avoidance of massive debridements.

DR. JaN BURCH (Houston, Texas): As mentioned by the authors ofthis paper, we do not use and have not used antivenin at the Ben TaubHospital, although admittedly most of OUT patients have suffered frombites of the copperhead. However we have had some serious bites, andwe have preferred to treat those with the more commonly used methodsofthe modero intensive caTe unit, including careful observation andtimely intervention based on the patient's condition.

1 would like to ask two questions of the authors. Were any bloodproducts used to treat coagulopathies that occurred in patients who weretreated "ith antivenin? Was there any evidence that patients treated withantivenin had less tissue necrosis than those who were nót?

DR. ROBERT A. WEBER (Closing discussion): Talking about antiveninuse is often like trying to answer the question whether Miller Lite beertastes great or is less filling. With the comments we have received thisafternoon, I find that this indeed holds true.

We view the treatment of snakebites as involving in two areas, localinjuries and systemic involvement. We think a local treatment, surgicalexcision of the bite wound, is best suited for the management of localtissue damage.

While laboratory results tend to indicate that antivenin reduces localtissue injury when given soon after the snakebite, we feel the high com-plication rate associated with the antivenin does not justify its routineuse in all circumstances. For systemic involvement, however, there islittle question that antivenin seems to ameliorate the effects of enven-omation. For this reason we use antivenin if and only if systemic in-volvement is presento

The question was raised regarding our rate of anaphylaxis. An articleby Jurkovitch in the Journal ofTrauma reported that 23% ofhis patientsdemonstrated an acute h)'j)ersensiti,it)' response and anaphylactic shock,and 50% had serum sickness. Another paper reported an overall corn-plication rate of 29%. Our numbers are consistent with the literature.

Dr. Pennell asked if we are seeing patients who are bitten on morethan one occasion. We are. One ofthe first patients 1 treated was seenin the emergency room for anaphylactic shock. This was his third biteat a rattlesnake roundup, and this time he developed asevere h)'j)ersen-sitivity reaction to the snake venom. No antivenin had yet been given.

Dr. Baker asked how much antivenin we give. We recommend 5 to10 vials at first, to be titrated to clínica! response.

Dr. Burch asked ifwe use any blood products in the patients treatedwith antivenin. We used a total of9 units offresh frozen plasma and 6units of packed red cells to treat envenomation associated coagulopathiesand bleeding in our patients. We feel the danger of AIDS and hepatitisassociated with the transfusion ofblood products outweighs the morbidityassociated with antivenin, therefore, decreasing or avoiding the use ofblood products by using antivenin is advantageous to the patient.

Thank you for the opportunity to present our data for discussion.

DR. WAY~E ScHWESINGER (San Antonio, Texas): Ob\'Íously someof these questions are becoming repetitive. 1 want to remind those ofyou left in the audience, however, that when controversies persist insurgery, one approach to answering those controversies is to go back t9the Jaboratorv.

That brinis to mind the fact that a resident recently conducted a studyin OUT laboratory on this very issue. Dr. Ron Stewart develOped, validated,and then studied a hind-limb rabbit model ora lixed-dosediamondbackrattler envenomation and noted that, in fact, the use of antivenin wasassociated with decreased swelling, improved survival, and retention ofmuscular activity when compared to either no specilic treatment or theuse of wide debridement.

So it appears that antivenin then would be justified in patients not

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