Acute Care Medicine - Anaphylaxis and Head Trauma

Question 1

Discuss the definition and diagnostic criteria for anaphylaxis

Answer 1

• is severe, hypersensitivity reaction that is rapid in onset and characterized by life-threatening airway, breathing and/or circulatory problems and associated skin and mucosal changes
  Diagnostic Criteria (one of the following)
• Acute onset of skin and/or mucosal involvement with one of respiratory compromise or reduced BP or associated end organ damage
• two or more following exposure to likely allergen
  
  • involvement of mucosal tissue
  • respiratory compromise
  • reduced BP or associated symptoms
  • gastrointestinal symptoms
• reduced BP after exposure to a known allergen

Question 2

Discuss the pathophysiology of anaphylaxis

Answer 2

First exposure have activation of B cells producing IgE antibodies -> IgE bind to mast cells -> re-exposure antigen bind to IgE leading to degranulation and

• Lipid mediators causing smooth muscle contraction
• PAF and tryptase leading to superficial and systemic vasodilation
• Histamine leading to increase vascular permeabiltiy and
  
  • utricaria which is fluid leak into superficial dermis
  • angioedema with fluid leak into dermis and subcutaneous tissue

Question 3

Discuss the treatment for anaphylaxis

Answer 3

• Vitals
• ABCDE
  
  • if evidence of airway collapse then intubate early to prevent difficulties due to swelling
• Intramuscular epinephrine 0.3-0.5mg to mid-thigh
  
  • can repeat q5 minutes for maximum 5 doses
  • 0.01mg/kg IM
• Place in recumbent position
  
  • feet elevated
• Oxygen 8-10L/min to keep O2 sat >92%
• Normal saline bolus with 1-2L IV for hypotension
• Salbutamol 2.5-5mg in 3mL saline nebulizer
  - for bronchospasm resistant to IM epinephrine

Question 4

Discuss the adjunctive therapies to anaphylaxis

Answer 4

• H1 antihistamine (Dimenhydramine 25-50mg IV over 5 min)
  
  • for utricaria and itching
• H2 antihistamine (Famotidine 20mg IV over 20 min)
• Glucocorticoid (methylprednisone 125mg IV Q6H)
• Monitoring

Question 5

Discuss the refractory therapies for anaphylaxis

Answer 5

Epinephrine infusion for inadequate response
- 0.1mcg/kg/min
Vasopressor if still unresponsive following epinephrine infusion
Glucagon for patients with beta-blocker
- 1-5mg IM to 5-15mcg/min IV

Question 6

Discuss the secondary biphasic reaction for anaphylaxis

Answer 6

• is the recurrence of symptoms that develop following the initial exposure with re-exposure
• Symptoms can be milder, the same or worse than initial exposure
• can present 1-72hrs following with median being 10-12 hrs
  
  • usually observe patient for 4-6hrs following last dose

Question 7

Discuss the criteria for admission and discharge for those with anaphylaxis

Answer 7

Admission
- severe reaction (hypotension) or requiring >1IM epinephrine dose
- Continue to be symptomatic following 6-8hr observation
- Pre-existing asthma or beta-blocker
- Very old or very young
Discharge
- provide written action plan
- educate on allergen avoidance
- close follow up with GP
- Medications
- Epipen
- Dimenhydramine 25-50mg PO Q4-6H for 3 days
- Ranitidine 150 Q12H for 3 days
- Prednisone 50 mg PO OD for 3 days

Question 8

Discuss the Canadian C-Spine Rule

Answer 8

- any GCS 15 and stable patient where C spine injury is of concern
High Risk Factors get X-ray
- age >=65 years
- dangerous mechanism
     - fall from >3 feet
     - axial load
     - MVC high speed
     - motorized recreational vehicle
     - bicycle struck
- paresthesia in extremities
Any Low Risk Factor Which Allows for ROM Assessment
- Simple rearend MVC
- sitting position in ED
- Ambulatory at time of injury
- delayed onset of neck pain
- absence of midline c-spine tenderness
Able to Actively Rotate Neck to 45 degrees

Question 9

Discuss the simple assessment of the C-spine

Answer 9

Examine Alignment
- Anterior vertebral line
- Posterior vertebral line
- spinolaminar line
Examine for Fracture
Examine Soft Tissue
- <6mm anterior to C2
- <20mm anterior to C6

Question 10

Discuss the CT Head Rule

Answer 10

- Must be GCS 13-15 after witnessed loss of consciousness, amnesia or confusion
High Risk
- GCS score <15 at 2 hrs after injury
- Suspected open or depressed skull fracture
- Any sign of basilar skull fracture
    - Racoon eyes
   - Battle signs
   - CSF otorrhea
- Vomiting >=2 episodes
- Age >=65
Medium Risk
- Amnesia before impact >=30 min
- Dangerous mechanism