Treatment of Yellow Scorpion (Leiurus quinquestriatus) Sting: A Case Report
Posted 12/07/2007
Eric A. Shalita; Ryan D. Wells
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Abstract
Objectives: To report the treatment given to a 26-year-old Air Force medic who was stung twice by a yellow scorpion (Leiurus quinquestriatus) while stationed in Iraq and to describe the problems and issues related to the use of the scorpion antivenin.
Patient Case: The patient presented 2 hours after envenomation to the local military treatment facility, where she was minimally symptomatic initially. Shortness of breath and anxiety developed, and the patient was sedated, intubated, and evacuated to a large Air Force medical facility for more advanced care. Vasopressor support was required during flight. At the medical facility, antivenin was administered, and the patient's cardiac condition was stabilized with norepinephrine drip, mild hydration, and vasopressor support. A second dose of antivenin diluted in sodium chloride and further pressor support were required. ST-segment depression eventually resolved, and the patient was gradually taken off norepinephrine and extubated. She recovered fully within 2 weeks and returned to active duty.
Discussion: Because the antivenin used is not licensed by the Food and Drug Administration, informed consent was needed; however, it could not be obtained because the patient was unconscious, intubated, and in a life-or-death situation. Antivenin selection is based on the species of scorpion and symptom severity; therefore, the scorpion should be, with great care, killed for identification. In the military setting, inventory control, storage, and accountability are vital issues surrounding antivenin use, and these are discussed in this article.
Conclusion: Immediate action and effective communication, along with timely antivenin administration and well-equipped intensive care facilities, were integral in saving the life of this victim of a yellow scorpion envenomation. All level 3 facilities in Southwest Asia must be familiar with ordering, administering, and documenting this antivenin because it is difficult to obtain and infrequently available.
Introduction
One of the most dangerous scorpions found in Southwest Asia is the yellow scorpion (Leiurus quinquestriatus), also known as the "death stalker scorpion" (Figure 1).[1,2] The yellow scorpion's venom is highly cardiotoxic and may cause irregular heartbeats, rapid changes in pulse and blood pressure, myocardial injury, and heart failure.[2-6]
Scorpion venom is a highly antigenic compound, made up of several proteins and enzymes that have known neurotoxic, cardiotoxic, nephrotoxic, and hemotoxic effects. The rapid action of these agents presents major issues. Treatment of patients with systemic symptoms should be initiated as soon as possible. Lethal dose is measured in milligrams injected per kilogram of body weight of the victim; thus, lower body weight is related to increased morbidity and mortality.[1,7] Most deaths reported occur within 24 hours and are related to respiratory and cardiovascular collapse.
Polyvalent scorpion antivenin (Equine—registered by the Ministry of Health in Saudi Arabia under registration no. 98/308/1) is a refined and highly purified preparation containing the F(ab')2 fraction of the immunoglobulin raised against scorpion venoms. The antivenin is prepared by hyperimmunizing healthy Arabian horses using gradually increasing doses of local scorpion venoms and immunomodulators. Polyvalent scorpion antivenins are highly specific in neutralizing the venoms of yellow scorpions, black scorpions (Androctonus crassicauda), and a variety of other scorpions found in the Middle East and North Africa. The antivenin also has a wide spectrum of activity and can neutralize the venoms of many of the scorpions, including Buthus arenicola, Butus mimax, Buthus occitanus, L. quinquestriatus hebreus, and Androctonus amoreuxi, found in that part of the world (Figures 2 and 3).[8]
Antivenin is a protein, in this case derived from equine sources. It acts as a denaturing agent, breaking up the four disulfide bonds that bend the venom protein into its characteristic folded shape. When these bonds are broken, the molecule relaxes into an inactive conformation.[9] While the product labeling for scorpion antivenin states that one dose of antivenin should be effective, redosing of a patient with multiple stings may be required to ensure that all of the venom has been denatured and inactivated.
Patient Case
A 26-year-old woman serving as an Air Force medic at an air base in Iraq presented to that base's medical facility 2 hours after scorpion envenomation. The scorpion was captured and identified by public health personnel as L. quinquestriatus. The patient reported two separate envenomations by the scorpion: one on the left hand and the other on the left side of the chest. Initially, the patient was minimally symptomatic with only mild discomfort at the sting sites. Arrangements were made for medical air evacuation to a facility with appropriate antivenin, and the pharmacists and physicians at the sending and receiving facilities communicated before transport was initiated.
The patient developed shortness of breath and anxiety over the subsequent 2 hours and was intubated and sedated before departure. During the helicopter flight to the Air Force Theater Hospital (AFTH), the patient lost her pulse and was administered a epinephrine 1 mg I.V. push on two occasions during the flight; her pulse recovered in both instances.
Upon arrival to the emergency department at the AFTH, the patient was noted to be intubated and sedated, with a wide complex tachycardia at a rate of approximately 130 beats per minute (bpm). Her initial blood pressure was 153/110 mm Hg. Within 1 to 2 minutes, she went into a junctional cardiac rhythm at a rate of 50 bpm. Three minutes after arrival, five 1 mL ampules of polyvalent scorpion antivenin (Figure 4) diluted in 0.45% sodium chloride 45 mL was administered over 30 minutes.
The patient had rhonchorous breath sounds bilaterally on chest auscultation. Her pupils were 4 mm to 2 mm bilaterally. She was moving all four extremities. The two reported sites of envenomation were not apparent upon physical examination. The patient's secondary physical examination did not reveal any further noteworthy findings.
Systolic blood pressure (SBP) fell into the 70 mm Hg range shortly after arrival. At that point, she was given epinephrine 100 mcg I.V. over 20 seconds. She was also placed on epinephrine 100 mcg in 100 mL 0.9% sodium chloride, given at a drip rate to maintain SBP at 85 mm Hg or greater. The patient's initial electrocardiogram revealed a sinus rhythm of 90 bpm, with up to 4-mm ST depression in leads V2 through V5 and a prolonged QT segment. Her chest X-ray film revealed good endotracheal tube placement and mild bilateral pulmonary vascular congestion.
The patient had a right femoral arterial line placed under sterile conditions in standard fashion. She then had a right subclavian triple lumen catheter placed under sterile conditions in standard fashion. For longer-term pressor support, the patient was placed on a norepinephrine drip titrated to maintain SBP greater than 85 mm Hg and titrated off the epinephrine drip.
The patient's cardiac condition at presentation to the AFTH emergency department had been stabilized by antivenin administration, mild hydration, and judicious vasopressor support. The patient's cardiac rhythm stabilized to a sinus rhythm at approximately 90-100 bpm. Her SBP stabilized around 90 mm Hg with the norepinephrine drip. However, after approximately 50 minutes, the patient was still requiring pressor support to maintain an acceptable blood pressure. At that point, a second dose of five 1 mL ampules of polyvalent scorpion antivenin diluted in 0.45% sodium chloride 45 mL was administered over 30 minutes.
The patient was moved from the emergency department to the intensive care unit (ICU). Blood pressure and heart rate stabilized, with a decreasing need for pressor support. A repeat electrocardiogram in the ICU revealed resolution of the previous ST segment depression. The QT prolongation continued. Over the next few hours, the patient was weaned off the norepinephrine and extubated.
Overnight in the AFTH ICU, the patient developed mild dyspnea. She was noted to have increasing pulmonary edema on chest X-ray films. Repeat cardiac enzymes were positive qualitatively. She was placed on 4 liters oxygen by nasal canula and given furosemide 20 mg I.V. She was stable for the remainder of her stay and moved by a critical care air transport team to the Landstuhl Army Regional Medical Center in Germany. An echocardiogram in Landstuhl revealed normal cardiac wall motion. The patient rapidly returned to baseline and, within 10 days, was ready for return to duty in Iraq.
Discussion
Several issues surrounding the use of antivenin made this both an interesting and challenging case. These are outlined in a policy letter provided to all pharmacies in level 3 military hospitals in Southwest Asia.[10] Level 3 hospitals have ICU capability and are similar to level 1 trauma centers in the United States.
The antivenin used in this case is not licensed by the Food and Drug Administration (FDA); it is produced by the Antivenom and Vaccine Production Center in Riyadh, Kingdom of Saudi Arabia. This means that technically, informed consent must be obtained before administering the antivenin to Americans. In this patient, however, this was not possible because she was unconscious, intubated, and in a life-or-death situation.
The non-FDA-licensed antivenins required for treatment of scorpion stings are only stocked at larger facilities within the United States Central Command area of responsibility, where they are prepositioned. These pharmacies stock antivenin for the most common poisonous snakes and scorpions in the region. If a scorpion sting occurs, consideration for the use of antivenin is based on species of scorpion and symptom severity. Therefore, without risking another sting, the scorpion should be killed and identified. If the scorpion is highly venomous, the victim should be transported immediately to the nearest medical facility with appropriate antivenin. Patients are at risk for hypovolemic shock, renal impairment, cardiac arrhythmias, and bleeding due to stings, as well as immediate and delayed hypersensitivity reactions from the antivenins.
While inventory control is a constant challenge in a combat zone, management of the ordering and distribution chain regarding these antivenins is even more tightly monitored. Only the pharmacy officer at the level 3 facility can order these agents, and stock levels are closely managed to avoid depleting or exhausting the supply. Storage also is a major challenge. These antivenins must be specially handled under refrigeration conditions and never frozen.
Control and accountability is vital because these antivenins are considered investigational products in the military system and are therefore managed in the same manner as controlled substances. Each vial or ampule is monitored closely. All receipts and expenditures must have justifying documentation, and a perpetual inventory is maintained.
These antivenins require specific reporting to ensure proper use and full documentation in the patient record. When an antivenin is ordered, the following information must be provided to the pharmacy service: full name and rank of the patient, branch of service of the patient, last four digits of the patient's Social Security number, antivenin product used, quantity of product used (number of vials and total number of milliliters or total dose), and patient's clinical outcome from the treatment, as well as the medical provider's name, rank, last four digits of Social Security number, and unit identification.
This information must be forwarded by the pharmacy service to the appropriate headquarters pharmacy staff officer, who then forwards it to FDA. Providing these data is essential to justify reordering. Additional antivenin stock will not be provided to the facility if this report is not provided, unless it is to replenish expiring antivenin stock. These reports are then forwarded to the U.S. Army Medical Research and Materiel Command's Chief of Regulatory Affairs. The Chief of Regulatory Affairs is required to report all use of these products to FDA.
Conclusion
Prompt action and effective communication by Air Force facilities, coupled with quick antivenin administration and comprehensive intensive care facilities, saved a patient's life. Because antivenins are difficult to acquire and only sporadically available, pharmacy officers at all level 3 facilities in Southwest Asia must be familiar with ordering, administering, and documenting these agents.
Source
http://www.medscape.com/viewarticle/566804_1
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Regards
Robin
