Page 46 - JSOM Summer 2020

– Overdosing antivenom is not a concern during the active treat- c. Once the patient has arrived at the clinic and can be placed
ment phase, and the worst-case scenario is an allergic reaction. in a bed, aggressively elevate the bitten limb (aim for a min-
If a patient did develop a reaction to large doses, it would most imum 60° angle in a supine patient if possible and tolerated
likely manifest as a late reaction called serum sickness (fever, by patient) to reduce oncotic pressure on swollen tissues.
rash, arthralgia, etc.) 1–3 weeks later and can be managed with 4. Evaluate for specific signs and symptoms of snake envenom-
antihistamines or steroids if the patient is uncomfortable. Se- ation. See Table 1 (page 47) and refer to Specific Criteria for
rum sickness may be uncomfortable but is not life-threatening. Initial Anti venom Treatment and Repeat Doses for additional
information.
Establish a timeline and trend changes over time: Serial assess-
ments and documentation are essential because the resolution of a. Perform a physical examination and history focused on
identifying signs and symptoms of neurotoxic, hemotoxic,
certain clinical findings will be used to determine when the right
dose of antivenom has been given. At a minimum always docu- and cytotoxic envenomations syndromes
i. Determine how long ago the bite occurred
ment the following:
1. Circle the site of the bite wound and write the spe-
– Time and date when bite occurred cific time that it occurred with a permanent marker
– Time elapsed from bite to presentation under your care (record on the patient
as minutes, hours, days, etc) ii. Do not rely on fang marks to assess the possibility of a
– Time when the first dose of antivenom is given (defined as bite or envenomation. Snakebites can leave punctures,
Hour 0, written as H0) multiple lacerations, or even no obvious fang marks
– Always repeat a complete snakebite assessment at hours 2, 4, whatsoever.
6, 12, and 24 (H2, H4, H6, H12, H24) since the first dose of iii. Rapid examination for signs of pain, swelling, or tissue
antivenom was given in order to trend the clinical evolution of destruction (cytotoxic syndrome)
the syndrome over time 1. Separately mark the leading edge of both pain
(dashed line) and edema (solid line) with a perma-
Snakebites are clinically dynamic emergencies: Patients can pres- nent marker and record time of observation next to
ent with one syndrome initially and develop signs and symptoms
each line
of another later on. For example, a patient who presents with lo- iv. Rapid examination for signs of local or systemic bleed-
cal pain and mild swelling at H0 could develop local bleeding or
ptosis at H4. Always look for signs and symptoms of all three ing (hemotoxic syndrome)
1. Inspect the bitten limb for persistent local bleeding
triads when reassessing.
> 30 minutes from the bite wound (if visible) or other
lesions. 1,69–71
Universal Approach to Snakebite Assessment, 2. Inspect the molar gingiva and other mucosa for signs
Diagnosis, and Treatment of systemic bleeding. 1,69,70
Initial Approach to the Snakebite Patient – v. Rapid examination for signs of neuromuscular weak-
Universal Recommendations ness (neurotoxic syndrome)
1. Airway, breathing, circulation, and rapid antivenom adminis- 1. Evaluate respiratory muscle weakness by single
tration are the critical priorities during stabilization and treat- breath count testing and repeat periodically to
72
ment of a snakebite casualty. trend improvement or deterioration in respiratory
a. Assess ABCs; identify and address any immediate life function over time.
threats before proceeding. Treat emergent secondary issues a. The single breath count (SBC) test requires no
that may be present (such as anaphylaxis or hypovolemic equipment to perform and is easily performed in
shock) according to standard clinical protocols. austere settings:
b. Establish IV or IO access in a non-bitten limb before i. Ask the patient to take a deep breath and
proceeding. count as high as possible in their normal
2. DO NOT apply constricting bandages or tourniquets as these speaking voice without taking another breath.
may worsen local tissue injury and increase the risk of perma- Demonstrate the test to the patient, then have
nent disability. 64–66 them repeat it and record the highest number
a. If a tourniquet is already in place, do not remove it until reached.
you are ready to treat and resuscitate the patient as a rapid 1. SBC correlates closely with spirometry.
decompensation can occur. 67,68 When removing a tourni- Normal SBC is approximately 50 and SBC
quet do so sequentially (loosen for several seconds–tighten– < 20 is associated with the need for me-
observe–repeat) over 20–30 minutes; if symptoms develop chanical ventilation.
at any time administer antivenom and wait at least 30 min- b. If spirometry is available, this can be used in place
utes before resuming tourniquet release. Ideally, this should of the single breath count test by evaluating the
not be done until antivenom is available but prolonged evac- negative inspiratory force (NIF) and/or forced vi-
uation times without antivenom may necessitate the risk tal capacity (FVC).
of earlier removal to prevent limb death. Refer to TCCC 2. Conduct gross assessment and pay particular atten-
guidelines for tourniquet conversion in these settings. tion to the following:
3. If and when conditions allow, minimize patient activity and a. Signs and symptoms of descending flaccid
loosely immobilize bitten limb to reduce movement without paralysis:
constricting tissues. i. Ptosis, diplopia, neck flexor muscle weakness,
a. If antivenom is not available onsite, choose whichever evac- bulbar weakness, etc. 1,54,73
uation option will safely get your patient to the antivenom b. Signs and symptoms of parasympathetic/cholin-
in the shortest amount of time. This includes allowing the ergic crisis:
patient to walk to help when needed. i. SLUDGE mnemonic–Salivation, Lacrimation,
b. If conditions allow during transport, maintain the bitten Urination, Defecation, GI distress, Emesis
limb in a position of comfort that is elevated above the level b. Perform and/or check the clinical laboratory tests listed be-
of the heart. low (if available)

44 | JSOM Volume 20, Edition 2 / Summer 2020