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***LISTEN TO THE PODCAST HERE***

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Background

• These studies are conducted at the Ottawa Hospital Research Institute and University of Ottawa starting in 1992 and the main researcher behind these is Ian Stiell.
• They are international recognized and have been validated multiple times to decrease unnecessary radiographic testing and decrease healthcare costs

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Disclaimer for Using Clinical Decision Instruments

• Your clinical judgement should ALWAYS trump using any CDI
  • Distracting injuries
  • Intoxication
  • Inability to fully examine
  • Gestalt

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Ottawa Rules of the Foot and Ankle

• The Numbers
  • Ankle xrays are the second most commonly ordered film in the ED
  • < 15% fracture incidence rate
• The study
  • Published in 1992, validated in 1995
  • 7 months long
  • 750 patients
  • 21 EM physicians looking at 32 clinical variables

• Variables
  • Lateral malleolus tenderness
  • Medial malleolus tenderness
  • Base of 5^th metatarsal tenderness
  • Navicular tenderness
  • Inability to bear weight immediately and in the emergency department for four steps
    • Limping counts
• Outcomes
  • Identified 100% of clinically significant fractures
  • Decreased ankle imaging 36% and foot imaging 21%

• Clinical Pearls
  • Be sure to palpate the entire 6cm of the distal tibia and fibula
  • Do not confuse soft tissue tenderness for bony tenderness

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Ottawa Rules of the Knee

• The Numbers
  • >600,000 patients annually present to ED with knee complaints
  • 80% of these patients have radiography
    • Majority have soft tissue injuries
• The study
  • Published in 1995, validated in 1996
  • 14 months long
  • 1,047 patients
  • 33 EM physicians looking at 23 clinical variables

• Variables
  • > 55 years of age
  • Isolated patella tenderness
  • Fibular head tenderness
  • Inability to flex knee to 90^o
  • Inability to bear weight immediately and in the emergency department for four steps
    • Limping counts
• Outcomes
  • Identified 100% of clinically significant fractures
  • Decreased knee imaging by 28%

• Clinical Pearls
  • Use only for injuries < 7 days old
  • Patella tenderness only significant if an isolated finding

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Ottawa Rules of the Cervical Spine

• The Numbers
  • C-spine series is the most common radiograph for trauma
  • > 1,000,000 series performed annually
    • > 98% being negative
• The study
  • Published in 2001, validated in 2003
  • 3 years long
  • 8,924 patients
    • Blunt trauma only
    • Stable vital signs
    • GCS of 15
  • Looked at 20 clinical variables

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• Variables
  • ≥ 65 years of age
  • Dangerous mechanism
    • Fall from height > 3 feet or 5 stairs
    • Axial load
    • High speed (> 60mph) MVC, rollover, or ejection
    • Motorized recreational vehicle accident
    • Pedestrian or cyclist versus automobile accident
  • Immediate pain
  • Non-ambulatory at scene
  • Inability to rotate neck
• Outcomes
  • Identified 100% of clinically significant fractures
  • Decreased cervical spine imaging by 42%

• Clinical Pearls
  • Not applicable if:
    • Non-trauma
    • GCS < 15
    • Unstable vital signs
    • Age < 16 years of age
    • Acute paralysis
    • Known vertebral disease
    • Previous cervical spine history

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Canadian Head CT Rule

• The Numbers
  • > 2 million ED visits annually for minor head trauma
    • Average cost of CT scan ~ $1200
      • Average annual cost > $900 million
  • < 3% incidence of clinically significant intracranial injuries
• The study
  • Published in 2001, validated in 2005
  • 3 years long
  • 3,121 patients
    • Blunt trauma only
    • GCS between 13-15
    • < 24 hours on presentations
    • Must have loss of consciousness, altered mental status, or amnesia
  • Across 10 academic hospitals
  • Looked at 22 clinical variables

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• Variables
  • High risk variables (need for neurosurgical intervention)
    • GCS < 15 at 2 hour after injury
    • Suspected open/depressed skull fracture
    • Signs of basilar skull fracture
    • ≥ 2 episodes of vomiting
    • ≥ 65 years of age

• Variables
  • Medium risk variables (predicting clinically important brain injury)
    • Retrograde amnesia ≥ 30 minutes
    • Dangerous mechanism
      • Pedestrian versus auto
      • MVC ejection
      • Fall from height > 3 feet or > 5 stairs

• Outcomes
  • Identified 100% of high risk patients and 98.4% of medium risk patients
  • Reduction in head CT by > 30%

• Clinical Pearls
  • Not applicable if:
    • < 16 years of age
    • On anticoagulation
    • Witnessed seizure post-injury
    • Unstable vital signs
    • Acute focal neurologic deficit

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Ottawa Rules for Subarachnoid Hemorrhage

• The Numbers
  • 2% of all ED visits are for headache
  • 2% incidence of subarachnoid hemorrhage
  • 51% mortality if missed
• The study
  • Published in 2010, validated in 2013
  • 5 years long
  • 1999 patients
    • Non-traumatic
    • < 1 hour from onset
    • GCS 15
  • Looked at 13 clinical variables

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• Variables
  • ≥ 40 years of age
  • Neck pain
  • Witnessed loss of consciousness
  • Exertional onset
  • Added on validation study:
    • Thunderclap headache
    • Limited neck flexion on exam
• Outcomes
  • Identified 100% of subarachnoid hemorrhages
  • 100% negative predictive value
  • Decreased head CT or lumbar puncture rates by 20%

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The Cottage Physician (1893)

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References

1. The Ottawa Rules. [online] Available at: http://www.theottawarules.ca/ [Accessed 10 Nov. 2019].
2. Stiell IG, Greenberg GH, McKnight RD, Nair RC, McDowell I, Worthington JR. A study to develop clinical decision rules for the use of radiography in acute ankle injuries. Annals of emergency medicine. 1992; 21(4):384-90. [pubmed]
3. Stiell IG, Greenberg GH, McKnight RD, et al. Decision rules for the use of radiography in acute ankle injuries. Refinement and prospective validation. JAMA. 1993; 269(9):1127-32. [pubmed]
4. Stiell IG, McKnight RD, Greenberg GH, et al. Implementation of the Ottawa ankle rules. JAMA. 1994; 271(11):827-32. [pubmed]
5. Stiell I, Wells G, Laupacis A, et al. Multicentre trial to introduce the Ottawa ankle rules for use of radiography in acute ankle injuries. Multicentre Ankle Rule Study Group. BMJ (Clinical research ed.). 1995; 311(7005):594-7. [pubmed]
6. Stiell IG, Greenberg GH, Wells GA, et al. Derivation of a decision rule for the use of radiography in acute knee injuries. Annals of emergency medicine. 1995; 26(4):405-13. [pubmed]
7. Stiell IG, Greenberg GH, Wells GA, et al. Prospective validation of a decision rule for the use of radiography in acute knee injuries. JAMA. 1996; 275(8):611-5. [pubmed]
8. Stiell IG, Wells GA, Hoag RH, et al. Implementation of the Ottawa Knee Rule for the use of radiography in acute knee injuries. JAMA. 1997; 278(23):2075-9. [pubmed]
9. Stiell IG, Wells GA, Vandemheen KL, et al. The Canadian C-spine rule for radiography in alert and stable trauma patients. JAMA. 2001; 286(15):1841-8. [pubmed]
10. Stiell IG, Clement CM, McKnight RD, et al. The Canadian C-spine rule versus the NEXUS low-risk criteria in patients with trauma. The New England journal of medicine. 2003; 349(26):2510-8. [pubmed]
11. Stiell IG, Wells GA, Vandemheen K, et al. The Canadian CT Head Rule for patients with minor head injury. Lancet (London, England). 2001; 357(9266):1391-6. [pubmed]
12. Stiell IG, Clement CM, Rowe BH, et al. Comparison of the Canadian CT Head Rule and the New Orleans Criteria in patients with minor head injury. JAMA. 2005; 294(12):1511-8. [pubmed]
13. Perry JJ, Stiell IG, Sivilotti ML, et al. High risk clinical characteristics for subarachnoid haemorrhage in patients with acute headache: prospective cohort study. BMJ (Clinical research ed.). 2010; 341:c5204. [pubmed]
14. Perry JJ, Stiell IG, Sivilotti ML, et al. Clinical decision rules to rule out subarachnoid hemorrhage for acute headache. JAMA. 2013; 310(12):1248-55. [pubmed]