Poijonouj Snakes of tho World 



riio viMioins of tlio oliipiWs uiv ((iiisiiUMahly <iif 

 iViviit ill llifir ilu'inifiil sinictinv from tli<)s<> of 

 llio viiuTS, mill llio si riirt Ill-ill vnriiitioiis williiii 

 llu^ vOMonis of llio family Klapitlsio aro (h'linilply 

 moro cnmplfx tliaii lliosi- williiii the families ("ro 

 taliilai> ami VipiTidat". PivsiMit know IimIjji' indi- 

 latps tiiat, in fiononil, olapid vt'iioms are absorhiMl 

 in i^ivaliT (|iiantiti(>s throiiixli llu- l>loo(l vessels 

 llian tliroufiii lymi)liati(: vessels. 



Both experimental and cliniral studies indicaie 

 tliat a constriction l)aiid is of (|uest ioi\al)lc vahie 

 following envenomat ion l>y an clapid. 'I'lie xaliic 

 of a lijrlil toiinii(iiiet is not so easily decided. 

 The rationale for using a tight tourniquet to oc- 

 iludo l)oth .suijcrfk-ial and deep blood vessels is 

 easily understood. However, it must be admitted 

 that adequate supimrtive evidence is still lacking. 

 N'evertheless, it seems best to advise placing a 

 tight tourni(iuet proximal to wounds inflicted by 

 large cobras, kraits, mambas, tiger snakes, death 

 adders, and taipans. Tourniquets should be left in 

 place only until antivenin is injected. Under no 

 circumstances should they bo used for more than 

 8 hours, and never without the usual i)recautions 

 associated with the use of a tourniquet. 



INCISION AND SUCTION 



Few problems in the first aid treatment of snake 

 venom poisoning liave elicited as much contro- 

 versy as incision and suction. Kecent experi- 

 mental studies have shown that in the case of 

 Ci'otahis envenomation, incision and suction at 

 the fang puncture woiuuls instituted within sev- 

 eral minutes of the bite, and suction continued 

 for no less than ."0 minutes, can remove a meas- 

 urable portion of the venom. The exudate ob- 

 tained from such incised wounds has been found 

 to produce the typical fall in systemic arterial 

 blood pressure, the increase in systemic venous 

 and cisternal pressures, the changes in cardiac 

 and respiratory rates, and the alterations in the 

 electrocardiogram and electroencephalogram ob- 

 served following injection of crude venom. The 

 exudate has also been found to be lethal to mice 

 in doses appi-oaching that of the crude venom. 

 Studies with I'-'^-labeled Crofahis venom indicate 

 that the toxin can be removed from properly in- 

 cised wounds by suction. These various experi- 

 mental studies strongly support the clinical im- 



piessioiis of thos*', physicians wiio have treated a 

 sullicient number of rattlesnake bites to \m in a 

 position to evaluaie I his first aid measure crit- 

 ically. 



Contrary to some opinion, few if any blood 

 vessels, leiulons, or other vital structures have 

 been iiijui'e<l by propei'ly executed cuts Ihrough 

 fang marks of Noith American i-attlesnakes. 

 There is no foundation foi- the, cDndemnat ion of 

 Ihis pi-oceduiHi on the basis thai vital siruclurcs 

 have been damaged dui-ing the execution of cuts. 

 There is also no support for the contention that 

 such lri\ial incisions will piuduce neural and 

 glandular activities which, in turn, increase the 

 lethal ell'ect of tho venom. 



According to some clinicians, incision and suc- 

 tion ihiough the fang wounds have not been 

 found tr) be effective following the bites of vipers 

 in Asia, Africa and parts of the Middle East. 

 While they are advised and nsed by some physi- 

 cians in these areas, others do not recommend 

 iheir use. Adequately controlled studies on the 

 depth (if fang penetration by the Old World 

 \ipers have not been done, but clinical evidence 

 would seem to indicate that these snakes bite 

 deeper than their North American cousins. If this 

 is ti'ue then incision and suction wo\ild be less 

 etl'ective than in North American crotalid bites. 

 AVhei'e intramuscular envenomation occurs, inci- 

 sion and suction are of no value and are not 

 recounnended. 



The lime of instigation and the manner in 

 which incisions have been made following bites 

 by vipers in Asia and Africa have been so in- 

 consistent that it is quite impossible to determine, 

 solely on the basis of clinical reports, whether or 

 not these measures are useful as first-aid measures 

 in poisonings by the Old AVorld vipers. It seems 

 best at this time to advise incision and suction in 

 most cases of viper venom poisoning. In no case, 

 however, should incisions be made deeper than 

 the subcutaneous tissues, and in those cases where 

 it is obvious that the fangs have penetrated 

 muscle tissue, no incisions should be made. 



Incision and suction through the fang marks 

 produced by the elapid snakes have not been 

 found useful. This may be because elapid ven- 

 oms are absorbed more directly into the blood 

 stieam than into lymphatic channels. It is not 

 ])ossil)le from the clinical re]>orts on elapid bites 



18 



