Intern Report 6.11

Case Presentation by Dr. Erin Ge

Chief complaint:

Seizure

History of present illness:

A 1 year old male presented to the ED with fever.  The previous night, his parents noticed that he felt warm to the touch.  He had been acting more tired than usual throughout the previous day, but was otherwise asymptomatic. While in the waiting room, the boy fell to the ground, became unresponsive and began to exhibit jerking motions of his arms and legs.  The jerking motions lasted for approximately 3 minutes and then ceased. The child had no history of seizures or any other major medical problems and he was developmentally normal.  There was no reported family history of seizures.

Review of Systems:

As stated in the HPI. Remaining ROS negative.

History:

Past Medical History:  None.

Past Surgical History:  None.

Medications:  None.

Allergies:  None.

Family History:  DM, no history of seizures, no history of childhood or inherited illnesses

Birth History:

Full-term, normal delivery

Birth weight: 6lb15ozs

Complications: neonatal jaundice which resolved with phototherapy, no other complications

Immunizations:

Up-to-date. No flu vaccine.

Initial Physical Exam:

General: Well nourished, unarousable male

Vitals:  T 39.8 rectal, HR 70, RR 32, BP 97/50, O2 Sat 100%, Wt 10kg

Head:  Normocephalic, atraumatic.

Eyes: PERRL, Normal conjunctiva

ENT: TM’s normal.  Mild rhinorrhea.  MMM. No evidence of tonsilar enlargement, edema or exudate.

Neck:  No nuchal rigidity. No cervical LAD.

Respiratory:  Clear to auscultation bilaterally. Respirations are nonlabored. Equal chest expansion bilaterally.

CVS:  RRR. S1, S2 normal.  No murmur.

Abdomen:  Soft, nondistended, nontender.  No palpable masses.  Bowel sounds normoactive.

Skin: Warm to the touch. No rashes.

Musculoskeletal: No obvious deformities.  Moving all extremities equally.

Neurologic: Not arousable, localizes physical stimuli, PERRL, normal deep tendon reflexes, normal tone

Repeat Physical Exam after 60 minutes

General: Awake, interactive male

Vitals:  T 37.6 rectal, HR 82, O2 Sat 100%

Neurologic: Alert, makes appropriate eye contact, interacting playfully with parents, PERRL, normal deep tendon reflexes, normal tone

Labs:

CBC: WBC 6.8   Hgb 10.8   Platelets 567

BMP: Na 133   K 144   Chloride 97   CO2 19   Glucose 104   BUN 14   Creatinine .4

Calcium 9.6    Magnesium 2.1  Phosphorus 5.4

Influenza A  –    Influenza B +   RSV –

Blood culture: No growth

Questions:

1)    Which of the following is true about the prognosis of a child with a first time simple febrile seizure?

a) Antiepileptic medications should be used to prevent further seizures

b) Likelihood of developing epilepsy is doubled

c) Over 75% of children under 12 months at time of first seizure will have another febrile seizure

d) Acetaminophen and ibuprofen use is effective in preventing recurrent febrile seizure episodes

2)    Which of the following patients who presented with fever and seizure should an LP be considered for?

a) 1 year old male who was diagnosed with acute otitis media one week ago and currently taking amoxicillin

b) 4 year old female who has been complaining of headache and asks for the lights to be turned off in the exam room

c) 10 month old male who has not been seen by a physician since being discharged after birth

d) b and c

e) all of the above

3)  Treatment of febrile status epilepticus includes which of the following?

a) Phenobarbital IV 15-18mg/kg loading dose, 5mg/kg repeat dose

b) Phenytoin IM 15-18mg/kg loading dose

C) All of the above

d) None of the above. Febrile seizures do not progress to status

 

Discussion & Answers

Question answers

1)  The answer is b.  Patients who have had febrile seizures have approximately a 2% incidence of epilepsy as adults which is twice the general population incidence of about 1%.

Answer a is incorrect. Although antiepileptic medications have actually been shown to decrease reoccurrence of febrile seizure activity in patients with a history of febrile seizures, they are typically not initiated due to the risk of medication effects outweighing the benefits of preventing a typically self limited seizure.  In a subset of patients who have increased risk for complications from seizures, however, these may be considered.

Answer c is incorrect. Having one simple febrile seizure does increase the risk of having another and increases it even more so the younger the patient is at time of initial seizure.  The risk, however is around 50% for patients younger than 12 months at first seizure and about 33% for patients older than 12 months.

Answer d is also incorrect.  Although use of ibuprofen and acetaminophen is commonly used to help break a febrile seizure, these medications have not been shown to have any effect on preventing seizure activity.

 

2)  The answer is e.  All of the described patients should raise some concern for a CNS infection.  The patient described in a is currently on antibiotics which can mask the presenting symptoms of a meningeal infection.  While clearly not an indication for an LP, extra consideration should be given to possible LP in this patient.  The patient described in b has other concerning neurological symptoms, headache and photophobia, which may be indicative of meningeal irritation.  The patient in c has not received proper vaccinations and patients without known immunization against Haemophilus influenzae b and Streptococcus pneumoniae are at increased risk for meningitis.  Once again, none of these are indications for LP, but they should increase your suspicion for an occult infection.

 

3)  The answer is a.  Status from febrile seizure should be treated in the same manner as status from any etiology.  First line treatments are benzodiazepines and if those fail to break the seizure phenobarbital can be given as a second line treatment.

Answer b is incorrect.  Although phenytoin is a second line treatment for status, it should not be given IM due to its poor absorption via this route and its tendency to cause hemorrhagic necrosis at the injection site.

Answer c is incorrect because answer b is incorrect as stated above.

Answer d is incorrect.  Although rare, febrile seizures can progress to status epilecticus.

 

Febrile Seizures

This patient presented with a brief, generalized seizure associated with fever which was followed by a short postictal state and then complete neurologic recovery.  This presentation in a previously neurologically normal patient between the ages of 6 months and 6 years is characteristic of a simple febrile seizure.  Febrile seizures are classified as “simple” when the seizure activity is generalized, lasts for less than 15 minutes and only occurs once within a 24 hour period.  Seizures are considered complex if they do not follow any one of the classifications of simple febrile seizures (ie seizures are focal, last longer than 15 minutes or occur more than once in a 24 hour period).  Febrile seizures typically will occur during the first day of illness and are often associated with higher elevations in temperature and when temperatures increase or decrease rapidly.

Febrile seizures are common and may occur in up to 5% of children.  They are typically benign in nature.  A small number of patients who present with complex febrile seizures do have underlying pathology, so clinicians should be more wary with a complex presentation.  In general, however, patients do not have any long term sequelae due to these seizures.  As previously discussed in the question answers, there is a greater risk of epilepsy in adulthood for patients who had febrile seizures, but it is still only seen in about 2% of this population.  Also as previously discussed, febrile seizures do often recur and while administration of antiepileptics can decrease recurrences, the risks associated with use of these medications is viewed as greater than the risk posed by the seizures in most children.  Factors shown to correlate with increased recurrence risk include: younger age at first seizure, first degree relative with history of febrile seizures, lower degree of fever in the ED and brief duration between onset of fever and seizure activity.

The treatment of febrile seizures is similar to that of any seizing patient.  The initial concern is to stop the seizure activity.  While febrile seizures usually are self limited in nature, they can also persist and rarely progress to status epilepticus.  First line treatment is administration of benzodiazepines, typically lorazepam or diazepam.  Preferred route is IV, but as IV access can be difficult in a seizing patient both lorazepam and diazepam are available and effective via rectal administration.  Midazolam has also been shown to be effective when administered intramuscularly.  If repeated doses of benzodiazapines do not break the seizure, the second line agents are phenytoin and phenobarbital.  As previously discussed, phenytoin should not be used intramuscularly due it poor absorption and tissue necrosis.  It should also not be administered at a rate faster than 1mg/kg/min as it is prepared with propylene glycol which can cause cardiac complications when infused at a higher rate.  Use of Fosphenytoin circumvents both these issues, but is significantly more costly.  Simultaneous reduction of fever is appropriate for patients.  Rectal acetaminophen and ibuprofen can be administered.

Patients diagnosed with simple febrile seizures typically do not require admission or further follow up as long as they have shown full neurologic recovery and the source of the fever does not require more intensive treatment.

There should be an appropriate investigation for etiologies of fever in children that would be treated i.e. pneumonia, otitis media, urinary tract infection…etc.

The diagnosis of febrile seizure should only be given when other causes for seizure have been ruled out either from the patient’s clinical presentation or further lab and/or imaging studies.  Patients who raise any suspicion for meningitis should receive steroids, antibiotic therapy, antivirals, and further work up including a lumbar puncture.  Any patient with signs of neurologic impairment prior to seizure activity or incomplete neurological recovery after seizure requires further workup.

What Happened

The patient presented in the case was brought back to the pod actively seizing since at that time there were no open spots in resuscitation.  He was administered rectal acetaminophen and was about to be given a dose of lorazepam when his seizure activity ceased.  As stated in the discussion, his history and clinical presentation did not seem to indicate an underlying pathology for his seizures other than the fever, so we chose to perform basic lab studies and observe him.  His labs results were within normal limits with the exception of testing positive for flu, as shown, and his neurological state upon re-evaluation was completely normal.  Our final impression was that this child had a simple febrile seizure secondary to fever caused by the influenza virus.  Our plan had been to discharge him home, but upon discussion we the family over concerns that the child may seize again, we did decide to admit him to observation overnight.  He was started on a course of oseltamavir and administered ibuprofen and acetaminophen for fever control.  Overnight, he did not have any further seizure activity.  He was discharged home the next morning and was given instructions to follow up in the neurology clinic.

Intern Report 6.10

Case Presentation by Dr. Sean Michael

Chief Complaint: “my stomach is killing me”

History of Present Illness :

57-year-old man with history of COPD and remote history of breast and testicular cancer who presents to the ED approximately 72 hours after an alleged assault in which he was struck with a bat multiple times in the left flank. He sought care on the day of the assault and had a negative urinalysis, chest x-ray, and plain films of the right hand and wrist and T- and L-spine. He reported that his pain had improved considerably while in the ED, and he was discharged home.

He returns today complaining of severe epigastric and left flank pain as well as multiple episodes of nausea and vomiting that began when he woke up this morning. He denies trauma in the interim and has otherwise been well with no recent illness, fever, chills, diarrhea, dysuria, or hematuria. His flank pain radiates to the left groin and is “sharp” and severe. It has been worsening since the onset this morning. He’s had no relief with ibuprofen 800 mg and Norco, which he was prescribed during his last ED visit.

Review of Systems : Negative except per HPI

Medications: albuterol, Norco, ibuprofen.

Medical history: remote history of breast cancer, remote history of testicular cancer, COPD

Surgical history: bilateral mastectomy (remote)

Social history: Denies alcohol use, current tobacco use, and illicit drug use

Physical Examination

Vital signs:  T 35.9, BP 143/99, HR 85, RR 18, SpO2 99% on room air, BMI 17.8

General:  Alert, anxious, diaphoretic. Ill-appearing and looks rather uncomfortable.

Skin:  Normal color for ethnicity.  Cool, diaphoretic.

Head:  Atraumatic

Neck:  Normal active ROM.  No tenderness, step-off, or deformity.  No JVD.

Eye:  PERRL, EOMI. Normal conjunctiva.

ENT:  Dry oral mucosa

Cardiovascular:  Regular rate and rhythm.  Normal S1 and S2. No murmur.  No edema.  Radial pulses strong and symmetric. Extremities well-perfused.

Respiratory:  Lungs are clear to auscultation bilaterally.  Respirations are non-labored. Symmetrical chest wall expansion.

Chest wall:  No tenderness, ecchymosis, deformity, or other evidence of trauma.

Abdomen:  Significant voluntary guarding. Upon focused relaxation, he has significant epigastric and left upper quadrant tenderness as well as left CVA tenderness. He has pain referred to the epigastrium upon palpation elsewhere in the abdomen. He has intense pain with gentle back and forth movement of the abdomen and with tapping on his heels.

Musculoskeletal:  Moving all extremities spontaneously, no deformity or evidence of trauma

Neurological:  Alert and oriented to person, place, time, and situation.  No focal neurological deficit observed.  Face symmetric. Grossly normal sensation, motor function, and speech.

 

IV access was established, and labs were sent including CBC, chemistries, coags, type and screen, LFTs, amylase, lipase, serum alcohol, UDS. He was bolused with IV normal saline and given IV morphine for pain control.

12-Lead EKG:

6.10 ECG

Chest X-Ray (upright): Old right-sided rib fractures but no acute cardiopulmonary abnormality. Mild hyperinflation. No evidence of pneumoperitoneum.

Bedside FAST exam was performed.

US-LUQ

Questions:

1. Based on the case information provided and this ultrasound image of the patient’s left upper quadrant, which of the following is the most appropriate next step in management?

A. Urgent consultation to urology

B. Urgent consultation to general surgery

C. CT abdomen/pelvis with PO and IV contrast

D. Urinalysis with microscopic exam

2. After administration of 2 liters of IV normal saline and 0.1 mg/kg morphine IV, the patient becomes hypotensive and complains of lightheadedness. Which of the following is the most appropriate next therapy?

A. IV crystalloid

B. Blood products

C. Naloxone

D. Diphenhydramine

 3. For which of the following patients is bedside FAST exam most appropriate and clinically helpful?

A. 40 year-old woman ejected from her motorcycle after a collision, HR 94 and BP 142/89

B. 23 year-old man with a gunshot wound to the right upper quadrant, HR 128 and BP 94/56

C. 28 year-old woman involved in a motor vehicle collision who has a “seat belt sign,” HR 92 and BP 132/78

D. 37 year-old male pedestrian struck by a vehicle at 30 mph, HR 112 and BP 102/60

 

Answers:

  1. B
  2. B
  3. D

 

Course in the ED:

In this case, bedside FAST exam was actually the first imaging obtained (17 minutes before the portable chest x-ray).

RUQ (positive for free fluid in the hepatorenal space and perihepatic areas):

US-RUQ

 

Suprapubic-transverse (fluid in the lumen of the bladder with a significant amount of free fluid in the pelvis):

US-PelvisTrans

 

Suprapubic-sagittal (same as above):

US-PelvisSag

The subxyphoid view was negative for pericardial effusion and is not shown.

The LUQ view (shown in question 1) was positive for a small amount of free fluid in the splenorenal space and much more free fluid in the perisplenic area. An urgent consultation was placed to general surgery (answer B). The patient was also crossmatched for 4 units of packed red blood cells and consented for transfusion, if necessary. After evaluating the patient, the surgery resident requested that we obtain a stat CT of the abdomen and pelvis with IV contrast. The patient remained hemodynamically stable and went to CT uneventfully.

Axial image through the mid-spleen:

Axialj

Sagittal image through the spleen and kidneys:

Coronalj

 

The CT demonstrated a grade 3 splenic laceration with significant hemoperitoneum and a large subcapsular hematoma, likely with a small amount of active extravasation.

While surgery was staffing the patient, the patient began having worsening discomfort and became more agitated. He became hypotensive to the mid-70s systolic with heart rate 110-115 and respiratory rate 30. At this point, the patient had already received at least two liters of crystalloid, and he was transfused with two units of packed red blood cells (question 2, answer B). Central venous access was obtained, and the patient was taken emergently to the operating room by general surgery.

He underwent exploratory laparotomy and was found to have a grade 4 splenic rupture with 3000 mL of blood in the abdomen and a grade 1 small bowel mesenteric hematoma in the jejunum. He received further pRBC transfusions in the OR, as well as Cell Saver autologous transfusion. He underwent splenectomy and was transferred to the SICU. His postoperative course was uneventful, and he was discharged home on post-operative day #4.

 

Discussion: imaging in blunt abdominal trauma

Emergency physicians are confronted with a broad spectrum of presentations of abdominal trauma, both blunt and penetrating. We also have at our disposal a variety of imaging options to evaluate and diagnose these injuries. As with any diagnostic test, however, it is important to understand the performance characteristics in order to appropriately select the right test in a given clinical situation.

Ultrasound:

Focused Abdominal Sonography for Trauma (FAST) is commonly performed as part of the assessment of all major trauma patients, but we sometimes rely on the result as being “black and white” (no pun intended) without fully understanding how to use the exam to inform the clinical picture. Conversely, some physicians discount the utility of ultrasound in the trauma patient altogether.

FAST is a triage tool, not a screening test. In other words, a negative FAST exam is not adequately sensitive to rule out intraperitoneal free fluid (pooled sensitivity 82%; -LR 0.26, 95% CI 0.19-0.34)(6). A positive FAST exam, however, is more accurate than any history or physical examination finding in diagnosing intra-abdominal injury (+LR 30, 95% CI, 20-46)(6). Thus, it is most clinically useful to rule-in injury, rather than to rule it out.

Evidence-based clinical practice guidelines from the American College of Emergency Physicians (ACEP), the Eastern Association for the Surgery of Trauma (EAST), and the American College of Radiology (ACR) are in agreement that FAST is the imaging modality of choice for hemodynamically unstable adult blunt abdominal trauma patients (1,2,4). In the setting of hemodynamic instability, a positive FAST convincingly rules-in intra-abdominal injury requiring operative intervention (1,2,4,5,6,7). A negative FAST, however, does not rule-out an abdominal injury.

Interesting Sidebar (compiled from reference 6):

Finding

Likelihood Ratio for Intra-abdominal Injury (95% CI)

Positive FAST 30 (20-46)
Base deficit less than -6 mEq/L 18 (11-30)
Presence of seat belt sign LR range 5.6-9.9
Rebound tenderness 6.5 (1.8-24)
Hypotension 5.2 ( 3.5-7.5)
Abdominal distention 3.8 (1.9-7.6)
Abdominal guarding 3.7 (2.3-5.9)
Absence of tenderness to palpation 0.61 (0.46-0.80)
Negative FAST 0.26 (0.19-0.34)

In the hemodynamically stable patient, ultrasound still provides useful information, but it’s clinical application is different. Because a positive FAST rules-in intra-abdominal injury, further evaluation is required to determine whether the stable patient requires operative intervention. In one prospective trial, the use of FAST in these patients reduced time-to-surgery by 109 minutes (64% reduction) and also reduced hospital length of stay, complications, and cost (5). Stable patients with a positive FAST should undergo CT (1,4). Depending on the pre-test probability of intra-abdominal injury, stable patients with a negative FAST may be candidates for observation, rather than immediate CT (4). The use of ultrasound for the evaluation of stable patients with blunt abdominal trauma has been shown to decrease CT utilization without deleterious effects on patient outcomes (5).

Of the patients described in question 3, the patient with unstable vital signs and blunt trauma (answer B) is most likely to benefit from FAST. There is a role for FAST in the stable blunt trauma patients (answers A and C), but less so than for the unstable patient. The hemodynamically unstable patient with penetrating abdominal trauma (answer D) requires emergent operative intervention, and FAST is very unlikely to add meaningful information (3,7).

CT:

The same authorities described above also agree that there is rarely a role for CT in the unstable trauma patient (1,2,4). For the stable patient, the preferred imaging modality is CT of the abdomen and pelvis with IV contrast, which enables detection of active bleeding (1,2,4,6). The American College of Radiology makes it clear that “CT evaluation of the abdomen and pelvis for blunt trauma does not require the use of oral contrast” (1). ACEP makes a level B recommendation that “oral contrast is not required in the diagnostic imaging for evaluation of blunt abdominal trauma” (question 1, answer C)(2). This includes the initial scan for patients suspected of having bowel injury (2).

CT has the advantage of better defining organ injury and identifying patients who may be candidates for nonoperative management of solid organ injuries (1). This is part of the rationale for obtaining a CT in stable patients with a positive FAST. It is possible to have intraperitoneal free fluid as a result of an injury that can be managed more conservatively. In addition, CT has the ability to visualize the retroperitoneum and vertebral column (1). While it is much more sensitive for solid organ injury than ultrasound, CT is not sufficiently sensitive to rule out some pancreatic, diaphragmatic, bowel, and mesenteric injuries (1). Therefore, patients with suspicion of intra-abdominal injury but negative CT should be observed for clinical changes that may suggest an occult injury (4).

 

Summary:

  • No imaging test is sufficiently sensitive to exclude clinically meaningful intra-abdominal injury in the setting of blunt abdominal trauma.
  • FAST is most useful when it is positive in a hemodynamically unstable blunt trauma patient.

 

References:

  1. American College of Radiology. “ACR Appropriateness Criteria: Blunt Abdominal Trauma.” (http://www.acr.org/~/media/ACR/Documents/AppCriteria/Diagnostic/BluntAbdominalTrauma.pdf). Accessed February 3, 2013.
  2. Diercks DB, Mehrotra A, Nazarian DJ, et al. Clinical policy: critical issues in the evaluation of adult patients presenting to the emergency department with acute blunt abdominal trauma. Ann Emerg Med. 2011;57(4):387–404.
  3. Como JJ, Bokhari F, Chiu WC, et al. Practice management guidelines for selective nonoperative management of penetrating abdominal trauma. J Trauma. 2010;68(3):721–733.
  4. Hoff WS, Holevar M, Nagy KK, et al. Practice management guidelines for the evaluation of blunt abdominal trauma: the East practice management guidelines work group. J Trauma. 2002;53(3):602–615.
  5. Melniker LA, Leibner E, McKenney MG, Lopez P, Briggs WM, Mancuso CA. Randomized controlled clinical trial of point-of-care, limited ultrasonography for trauma in the emergency department: the first sonography outcomes assessment program trial. Ann Emerg Med. 2006;48(3):227–235.
  6. Nishijima DKD, Simel DLD, Wisner DHD, Holmes JFJ. Does this adult patient have a blunt intra-abdominal injury? JAMA. 2012;307(14):1517–1527.
  7. Offner P. “Penetrating Abdominal Trauma Treatment & Management.” eMedicine website. (http://emedicine.medscape.com/article/2036859-overview). Accessed February 3, 2013.

COW

COWj

G. Patrick Daubert 
KPNC Regional Toxicology Service
Kaiser Permanente
South Sacramento Medical Center

 

51-year-old man presents to the ED after being bit by a snake.  Apparently, he handles snakes as a hobby.  He tells you (with a tear in his eye) the snake is a 9-foot long, female Bushmaster.  He was feeding the snake a rat when it apparently bit him on the dorsum of the right hand.  He tried to drive himself to the hospital but had to pull off of the road because he was concerned that he may crash his car.  He is complaining of some numbness and tingling in the hand and a “funny” sensation around his mouth.  The patient has pain and swelling of his right hand.  He is right handed.  He tells you he had a snakebite about 30 years ago and was treated with antivenom and reportedly had a “minor” reaction at that time.

PMHx/SurgHx: None

Allergies: None

Meds: None

Soc.  He has a history of alcoholism but has not had any alcohol to drink for the past five to six years. He denies tobacco use and does not have any history of any illicit or intravenous drug use.  The man apparently is a neuropsychologist (with reptiles as a hobby).

vs.  T37.7 BP168/119 RR16 HR131

MUSCULOSKELETAL:   He has intact distal pulses. There is significant swelling of the dorsum of his right hand, and there is evidence of a singular wound which is approximately 4 to 5 mm in length over the dorsum of his right hand.  The other extremities have no evidence of any swelling or deformity.

SKIN:  He has a very slight amount of erythema over his abdominal wall and slightly over his forehead, but there is no distinct urticaria. There are no vesicles or pustules, no ulcerations, or any other lesions noted on his skin.  There are no petechiae or ecchymoses noted.  A right femoral central venous line in his right inguinal region was started and there is evidence of some oozing of blood from the insertion site

  1. What is a Bushmaster snake and what is it doing in Michigan?  What type of venom does this snake possess?
  2. How would you initially manage this case?  Based on this envenomization, what labs do you order?
  3. What antivenomn do you use for this snake?  How do you dose/administer antivenom?  What types of antivenom do you commonly have in the ED?  Where do you find more or exotic antivenom?

a) First set of labs come back

b) Na 144, K 3.5, Cl 112, HCO3 23, BUN 21, Cr 1.5, Ca 8.6

c) WBC 28.6, Hb 17.6, Plt 324

d) PT/PTT/INR 22.3/26/2.06, D-dimer 92, Fibrinogen < 50

  1. Does the history of a previous snakebite and treatment of concern?
  2. This patient came back to the hospital (today as a matter of fact) complaining of not feeling well, general body aches, and dark urine.  What illness has he now developed and why?
  3. There are generally two classes of poisonous snakes in the U.S.  What are they and what is the typical clinical picture for each?
  4. When your friend Roger calls you from Joshua Tree in California on his mobile phone stating that he was just bit by a rattlesnake, what first-aid measures do you immediately recommend?
  5. Name the 5 T’s associated with snakebites.

Answers & Discussion

  1. What is a Bushmaster snake and what is it doing in Michigan?  What type of venom does this snake possess?

COW-1Bushmaster (Lachesis muta) is the largest pit viper, up to 3.6 m and is found in southern Central America and northern South America.  Bushmaster bites are rare (we had two of these in as many months this fall), but the case fatality rate is high.  Bushmasters are native to southern Central America and almost all the northern half of South America.  This snake’s venom is not as potent as other related species.  However, bushmasters produce an enormous amount of venom. The average yield of dried venom from a bushmaster is 411 mg (0.014 oz), compared to just 52 mg (0.0018 oz) from the copperhead.

  1. How would you initially manage this case?  Based on this envenomization, what labs do you order?

There are several initial concerns with snakebites (besides acute death) that need to be on your radar screen.  Patients may initially develop an anaphylactic reaction to the snakebite causing immediate airway compromise and hypotension.  We have seen significant facial/oral edema in our two bushmaster snakebite cases.  The second main concern is, of course, the effects of the snake’s venom. 

Venom is very complex with a multitude of components.  The venom from the bushmaster is primarily hemorrhagic.  One portion of the bushmaster’s hemorrhagic venom is LHF-I.  Lachesis Hemorrhagic Factor I (LHF-I) is a glycoprotein that hydrolyzes the alpha-chain of fibrinogen (greater than the beta-chain) and hydrolyzes selectively the alpha-chain of fibrin, leaving the other chains unaffected.  This, of course, leads to a significant coagulopathy.  In fact, the first patient we had, his blood wouldn’t clot on any of the DMC machines.  We were using a stopwatch to time the coagulation times and dosing antivenom accordingly.

The labs in this case need to focus on the coagulation cascade.  A CBC, coag profile, fibrin, fibrinogen, and D-dimer are needed.  Electrolytes and a urine analysis will also help in the initial management.  Local wound care is important here is well.  Localized edema occurs early and may be rapid.  The affected limb should have areas marked to measure sequential circumferences.  For instance, this patient was bit on the hand.  We marked off zones with a marker at the hand, forearm, elbow, and upper arm to measure circumferences every 15-30 minutes.  An advanced edge of swelling should also be marked.  Continued swelling is an indicator of the need for more antivenom.  A compartment syndrome may develop.  If this occurs, the limb should be elevated and more antivenom administered.  Please try and keep the surgeons away from this until your medical management is exhausted (including mannitol).  Tetanus immunization should be updated based on the patient’s history.

  1. What antivenomn do you use for this snake?  How do you dose/administer antivenom?  What types of antivenom do you commonly have in the ED?  Where do you find more or exotic antivenom?

Many emergency departments will stock either Wyeth [Antivenin (Crotalidae) Polyvalent (ACP) (horse)] or CroFab® [Crotalidae PolyvalentImmune Fab (sheep)] antivenom, but many do not.  The resources for finding antivenom are twofold.  Call the poison center or call the Zoo.   Poison centers will help you track down the antivenom you need.  Most zoos have snakes and therefore are required to have antivenom.  In this case, we tracked down antivenom through the Detroit, Toledo, Cincinnati, and Kentucky zoos.  We used these sources to track down Lachesis antivenom from Costa Rica.  Cool.

It is common in the literature to see skin testing recommended before the use of equine-based antivenom.  However, skin testing has no predictive value. A negative skin test does not guarantee lack of hypersensitivity; conversely, a positive skin test does not predict the development of an acute reaction.  In summary, don’t worry about doing it.  If a reaction occurs during antivenom administration, stop the infusion (early reactions usually result from too rapid an infusion rate). After administration of epinephrine, H1 and H2 blockers, and isotonic fluids, the antivenom can be further diluted and the infusion resumed at a slower

rate.

    1. First set of labs come back
    2. Na 144, K 3.5, Cl 112, HCO3 23, BUN 21, Cr 1.5, Ca 8.6
    3. WBC 28.6, Hb 17.6, Plt 324
    4. PT/PTT/INR 22.3/26/2.06, D-dimer 92, Fibrinogen < 50

Due to our previous experience and in knowing the snake, we felt that Wyeth (ACP) was our best bet for the bushmaster until we could get the Lachesis antivenom.  In general, patients who have minimal envenomation require no antivenom, moderate cases usually require 10 to 15 vials (100–150 mL) of ACP initially, and severe cases at least 15 vials (150 mL). Patients who have profound circulatory collapse should receive 20 vials (200 mL) initially (CroFab is dosed as 6 vials initially).  Reconstituted ACP antivenom should be diluted in 250 to 1000 mL of normal saline or 5% dextrose in water and given by IV drip, slowly, at 50 to 75 mL/hour for the first 10 minutes.  If no reaction occurs, the remainder can be infused over 1 hour.  Antivenom should never be injected into the finger or toe.  The need for additional antivenom doses should be guided by monitoring for progression of local, systemic, or coagulopathic abnormalities. If local findings, other signs, or laboratory test results progress, the initial dose of antivenom is repeated every 1 to 2 hours.

  1. Does the history of a previous snakebite and treatment of concern?

Absolutely!  This should prompt you to have epinephrine, H1 and H2 blockers, and steroids at the ready.  Close monitoring is essential as this patient may develop a life threatening hypersensitivity reaction.

  1. This patient came back to the hospital (today as a matter of fact) complaining of not feeling well, general body aches, and dark urine.  What illness has he now developed and why?

This is serum sickness.  Roughly every vial of antivenom administered increases your risk of serum sickness by 10%.  So, once you get 10 vials you are going to inevitably develop serum sickness.  As you may recall, serum sickness is a type III hypersensitivity reaction usually appearing 5-14 days after administration of an allergen.  It is characterized by fever, arthralgias, skin rash and lymphadenopathy.  Treatment should begin in the hospital with a 3-week course of tapering steroids.  Otherwise, the treatment is supportive with diphenhydramine and prednisone.  Symptoms usually resolve in a few weeks.

  1. There are generally two classes of poisonous snakes in the U.S.  What are they and what is the typical clinical picture for each?

Only 25 of the more than 120 species of snakes indigenous to the United States are venomous. The majority of these snakes belong to the subfamily Crotalinae (pit vipers: rattlesnakes, cottonmouths, and copperheads). The coral snake (Elapidae) is the only other native venomous snake. At least one species of indigenous poisonous snake has been identified in every state except Alaska, Maine, and Hawaii.

  1. When your friend Roger calls you from Joshua Tree in California on his mobile phone stating that he was just bit by a rattlesnake, what first-aid measures do you immediately recommend?

Place him at rest, reassure him, and keep Roger warm, and then get Roger to the nearest medical facility as soon as possible. The injured area should be immobilized in a functional position below the level of the heart. All rings, watches, and constrictive clothing should be removed.  Previously recommended first aid measures involving the use of tourniquets, incision and suction, cryotherapy, and electric shock therapy are strongly discouraged.  The Sawyer snakebite extractor on the market doesn’t work.  It has been proven more than once that is doesn’t extract any significant amount of venom.  Tell Roger to throw it away.

  1. Name the 5 T’s associated with snakebites.

He has all his Teeth, no Tattoos, was not inToxicated, apparently does not own a Truck, and of course, is a male and therefore has Testaterone.  This list is provided as a summary of the 5 T’s of snake bites – typically people are missing teeth, have tattoos, are intoxicated and own a truck.  Most are male.  Yet, another reason why women are smarter then men.