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Emergency Medicine - Clinical Rules and Guidance - Fast Facts | NEJM Resident 360

In this section, we review the following clinical rules and provide links to relevant online calculators and videos.

Head

• Canadian CT Head Injury/Trauma Rule

• New Orleans/Charity Head Trauma/Injury Rule

• PECARN Pediatric Head Injury/Trauma Algorithm

• NIH Stroke Scale/Score

Otorhinolaryngology (ENT)

• Centor Score (Modified/McIsaac) for Strep Pharyngitis

Neck

• NEXUS Criteria for C-Spine Imaging

• Canadian C-Spine Rule

Extremities

• Ottawa Knee Rule

• Ottawa Ankle Rule

• Wells Criteria for Deep-vein Thrombosis

Heart

• HEART Score for Major Cardiac events

• San Francisco Syncope Rule

• Boston Syncope Rule

Lungs

• Wells Criteria for Pulmonary Embolism

• CURB-65 Score for Pneumonia Severity

Abdomen

• Alvarado Score for Acute Appendicitis

• Ranson Criteria for Pancreatitis Mortality

Clinical Rules

Head

Canadian CT Head Injury/Trauma Rule

This rule is designed to identify patients with head injury who can be safely discharged without imaging. It applies to patients with a Glasgow Coma Scale score (GCS) of 13–15 with loss of consciousness (LOC), amnesia to the head injury event, or confusion. In alcohol-intoxicated patients, the sensitivity has been reported to be 70% for “clinically important” brain injury. Exclusions include age <16 years, anticoagulation, or seizure after injury.

High-risk criteria (derived with endpoint of need for neurosurgical intervention):

If any of the following are positive, obtain CT scan:

• GCS <15 within 2 hours after injury

• suspected open or depressed skull fracture

• any sign of basilar skull fracture (hemotympanum, raccoon eyes, Battle sign—mastoid ecchymosis, cerebrospinal fluid [CSF] otorrhea or rhinorrhea, cranial nerve abnormality)

• ≥2 episodes of vomiting

• age ≥65 years

**
Medium-risk criteria** (in addition to the above, rules out “clinically important” brain injury):

If any of the following criteria are positive, obtain CT scan:

• amnesia retrograde to the event ≥30 minutes

• “dangerous” mechanism (e.g., pedestrian struck by motor vehicle, occupant ejected from motor vehicle, fall from >3 feet or >5 stairs, fall from more than 2 times patient’s height, and other event deemed dangerous by physician)

*

New Orleans Criteria/Charity Head Trauma/Injury Rule*

Like the Canadian CT Head Injury Rule, these criteria identify which patients are unlikely to require imaging after head trauma and are for use in patients who have had head injury with LOC who are neurologically normal (GCS 15 and normal brief neurological exam).

If any of the following criteria are positive, consider CT:

• headache

• vomiting

• age >60 years

• alcohol or drug intoxication

• persistent anterograde amnesia (short-term memory deficits)

• visible trauma above the clavicle

• seizure

The New Orleans and Canadian Clinical Decision Rules for CT after Concussion
New Orleans Criteria — Glasgow Coma Scale score of 15
Headache
Vomiting
Age >60 yr
Drug or alcohol intoxication
Persistent anterograde amnesia (deficits in short-term memory)
Evidence of traumatic soft-tissue or bone injury above clavicles
Seizure

Canadian CT Head Rule — Glasgow Coma Scale score of 13–15 for patients 16 years and older
High risk of neurosurgical intervention
Glasgow Coma Scale score <15 within 2 hr after injury
Suspected open or depressed skull fracture
Any sign of basal skull fracture
Two or more episodes of vomiting
Age >65 yr
Moderate risk of brain injury detected by CT
Retrograde amnesia for ≥30 min
Dangerous mechanism |

(Adapted from: Concussion. N Engl J Med 2007.)

PECARN Pediatric Head Injury/Trauma Algorithm

The Pediatric Emergency Care Applied Research Network (PECARN) clinical rule is for pediatric head trauma. Like the head rules described above, this validated algorithm helps identify children at low risk of clinically important head injury who do not require imaging. Of note, physician experience and parental preference are important considerations for the intermediate-risk group and did factor into the ultimate results of the study.

PECARN Algorithm for Children after Head Trauma

NIH Stroke Scale/Score

This scale was developed to quantify the severity of a stroke in the acute setting. Increasing scores correlate with severity and clinical outcomes. Documentation of the scale is important for neurologists; however, it should not delay consultations, workup, or care. This scale is long and complicated. Instructions and details of the scale can be found here.

Although a score <4 generally is associated with good clinical outcome and functional independence, it should not preclude the need for imaging.

Components of the NIH Stroke Scale

Response	Scoring Definition
Level of Consciousness (LOC)	Alert; keenly responsive (0)
Not alert; arousable by minor stimulation (1)
Not alert; requires repeated stimulation (2)
Unresponsive; responds only with reflex (3)
LOC questions (Ask age; current month):
Answers both questions correctly (0)
Answers one question correctly (1)
Answers neither question correctly (2)
LOC commands (close eyes; squeeze hand):
Performs both tasks correctly (0)
Performs one task correctly (1)
Performs neither task correctly (2)
Best Gaze	Normal (0)
Partial gaze palsy; gaze is abnormal (1)
Forced deviation or total gaze paresis (2)
Best Visual Field	No visual loss (0)
Partial hemianopia (1)
Complete hemianopia (2)
Bilateral hemianopia (3)
Facial Palsy	Normal symmetrical movements (0)
Minor paralysis (1)
Partial paralysis (2)
Complete paralysis of one or both sides (3)
Motor Arm (left and right)	No drift; limb holds for full 10 seconds (0)
Drift; limb holds but drifts down (1)
Some effort against gravity; cannot maintain (2)
No effort against gravity; limb falls (3)
No movement (4)
Amputation or joint fusion, explain:
Motor Leg (left and right)	No drift; leg holds for full 5 seconds (0)
Drift; leg falls by the end of 5 seconds (1)
Some effort against gravity (2)
No effort against gravity (3)
No movement (4)
Amputation or joint fusion, explain:
Limb Ataxia	Absent (0)
Present in one limb (1)
Present in two limbs (2)
Amputation or joint fusion, explain:
Sensory	Normal; no sensory loss (0)
Mild-to-moderate sensory loss (1)
Severe or total sensory loss (2)
Best Language	No aphasia; normal (0)
Mild-to-moderate aphasia (1)
Severe aphasia (2)
Mute, global aphasia (3)
Dysarthria	Normal (0)
Mild-to-moderate dysarthria (1)
Severe dysarthria (2)
Intubated or other physical barrier, explain:
Extinction and Inattention (formerly Neglect)	No abnormality (0)
Visual, tactile, auditory, spatial, or personal inattention (1)
Profound hemi-inattention (2)

Otorhinolaryngology (ENT)

Centor Score (Modified/McIsaac) for Strep Pharyngitis

This score is for use only in patients with recent-onset (≤3 days) acute pharyngitis. It is used to predict which patients will have culture-confirmed streptococcal infections to minimize testing.

A score 0–1: no testing required
A score >1: test and treat according to result

Modified Centor Score criteria:

• age 3–14 years (+1)

• age 15–44 years (0)

• age ≥45 years (-1)

• exudate or swelling on tonsils (+1)

• tender/swollen anterior cervical lymph nodes (+1)

• fever >38°C, 100.4°F (+1)

• cough present (0)

• cough absent (+1)

Neck

NEXUS Criteria for C-Spine Imaging

These criteria were derived to identify patients who are eligible to be cleared clinically, without imaging. If no findings are present, risk of dangerous cervical spine fracture is very low.

If any of the following criteria are positive, obtain CT scan:

• altered level of consciousness

• intoxication

• distracting injury

• focal neurologic deficit

• midline cervical spinal tenderness to palpation

*

Canadian C-Spine Rule*

The Canadian C-Spine Rule is a validated decision rule that can be used to safely rule out cervical-spine injury in alert, stable trauma patients without the need to obtain radiographic images. It can also be used for stable trauma patients. In contrast with NEXUS (described above), the rule can be used if a patient is alert and cooperative, regardless of blood alcohol content.

However, strict exclusion criteria include the following:

Canadian C-Spine Rule exclusion criteria:

• nontrauma patient

• GCS <15

• unstable vital signs

• age <16 years

• acute paralysis

• known vertebral disease

• previous C-spine surgery

Canadian C-Spine Rule

Extremities

Ottawa Knee Rule

Knee imaging is not warranted in patients identified to be at low risk for fracture. This rule should be applied to all patients age ≥2 years with knee pain/tenderness in the trauma setting.

Patients who do not meet any of the following criteria do not need an x-ray. If one or more of the conditions are met, then imaging is recommended.

• age ≥55

• isolated tenderness of the patella (no other bony tenderness)

• tenderness at the fibular head

• unable to flex knee to 90°

• unable to bear weight both immediately and in emergency department (ED) (four steps, limping is okay)

*

Ottawa Ankle Rule*

This rule was also developed to reduce the use of unnecessary radiographs. You can apply this rule for patients age ≥2 years to rule out clinically significant ankle and mid-foot fractures after trauma without radiograph.

Patients who do not meet any of the following criteria do not need an ankle or foot radiograph. Those that fulfill either the foot or ankle criteria need an x-ray of the respective body part.

Wells Criteria for Deep-Vein Thrombosis

According to the Wells clinical decision rule, an ultrasound to rule out deep-vein thrombosis (DVT) is not necessary in patients deemed low risk with a negative D-dimer test result.

Interpretation of the Wells score:

A score of 0: DVT unlikely

• If the D dimer is negative, no further imaging is required.

• If the D dimer is positive, obtain an ultrasound.

• A negative ultrasound is sufficient to rule out DVT.

• If ultrasound is positive, consider treatment with anticoagulation.

A score of 1–2: moderate risk

• If high-sensitivity D dimer is negative, no further imaging is required.

• If the D dimer is positive, obtain an ultrasound.

• A negative ultrasound is sufficient to rule out DVT.

• If ultrasound is positive, consider treatment with anticoagulation.

A score of ≥3: likely DVT

• All patients require ultrasound and D-dimer test.

• If ultrasound is positive, treat with anticoagulation.

• If the D dimer is positive and ultrasound is negative, repeat ultrasound in 1 week.

• If the D dimer and ultrasound are negative, no further workup required.

Wells Criteria for Predicting Pretest Probability of DVT

Clinical Features	Score
Active cancer	+1
Bedridden recently (>3 days) or major surgery within 4 weeks	+1
Calf swelling more than 3 cm compared to the other leg	+1
Collateral (nonvaricose) superficial veins present	+1
Entire leg swollen	+1
Localized tenderness along the deep venous system	+1
Pitting edema confined to the symptomatic leg	+1
Paralysis, paresis, or recent immobilization to the lower extremity	+1
Previously documented DVT	+1
Alternative diagnoses to DVT as likely or more likely	-2

(Reference: Value of assessment of pretest probability of deep-vein thrombosis in clinical management. The Lancet 1997.)

Heart

HEART Score for Major Cardiac Events

Chest pain is a common complaint in the emergency department. This score predicts the 6-week risk of major cardiac events, thus helping clinicians determine appropriate disposition.

A score of 0–3: appropriate to discharge
A score of 4–6: admit to the hospital
A score of ≥7: candidates for early invasive measures

HEART Score criteria:

• slightly suspicious history (0)

• moderately suspicious history (+1)

• highly suspicious history (+2)

• normal electrocardiogram (ECG) (0)

• nonspecific repolarization disturbance in the ECG (+1)

• significant ST depression (+2)

• age <45 years (0)

• age 45 to 65 years (+1)

• age >65 years (+2)

• no known risk factors (0)

• one or two risk factors (+1)

• more than three risk factors or history of arteriosclerotic disease (+2)

• initial troponin within normal limit (0)

• initial troponin one or two times the normal limit (+1)

• initial troponin more than two times normal limit (+2)

*

San Francisco Syncope Rule*

The San Francisco Syncope rule can be used to separate patients with syncope into high-risk and low-risk groups. The high-risk group is associated with serious adverse outcomes (e.g., death, myocardial infarction [MI], arrhythmia, pulmonary embolism [PE]) within 30 days. The rule has been studied in several different settings and countries. Some controversy exists about the sensitivity of this rule to predict a bad outcome, particularly in different geographic regions.

If the patient meets any of the following criteria, he/she cannot be considered low risk:

• history of congestive heart failure

• hematocrit <30%

• ECG abnormal (ECG changed, or any nonsinus rhythm on ECG or monitoring)

• symptoms of shortness of breath

• systolic BP <90 mm Hg at triage

*

Boston Syncope Rule*

This rule predicts adverse events or need for critical interventions in patients who had syncope.

A patient with one of the risk factors should be admitted. If the patient does not have any of the risk factors, the patient can be safely discharged home. In one study, use of the Boston Syncope criteria reduced admissions by 11%. The OESIL Score for syncope estimates 12-month all-cause mortality in patients presenting with syncope

Lungs

Wells Criteria for Pulmonary Embolism

The Wells criteria for pulmonary embolism (PE) is used to determine the pretest probability of PE, which in turn influences the best next steps to rule out or rule in the diagnosis of PE.

Wells Criteria for Pulmonary Embolism

The Wells score can be interpreted as follows:

• score <2: low risk for PE

• score 2–6: intermediate risk for PE

• score >6: high risk for PE

Low-Risk Wells Score: Patients who have a Wells score <2 are at low risk for PE (incidence, 1.3%) and are typically further risk stratified using the Pulmonary Embolism Rule-out Criteria (PERC):

• age <50 years

• heart rate <100 beats per minute

• oxyhemoglobin saturation ≥95%

• no hemoptysis

• no estrogen use

• no prior DVT or PE

• no unilateral leg swelling

• no surgery or trauma requiring hospitalization within the prior 4 weeks

If all eight of these criteria are met, then no further testing is needed. If any of the criteria are not met, then a D-dimer measurement can be helpful; a normal value can help rule out PE and obviate the need for imaging.

Intermediate-Risk Wells Score: In intermediate-risk patients (Wells score of 2–6; incidence of PE, 16.2%), a D-dimer level is indicated. If the D-dimer level is <0.5 µg/mL, further imaging is typically not needed. However, the full clinical picture should be taken into account for patients who fall into this group. Imaging to rule out PE may be appropriate for some intermediate-risk patients, regardless of D-dimer value. This may apply to older patients, those with cardiopulmonary compromise, those with a Wells score at the upper end of the intermediate range, and other patients where the clinical evaluation raises concern for PE beyond what is reflected in the Wells score.

High-Risk Wells Score: Imaging (usually CT angiography) should be obtained in all high-risk patients (Wells score >6; incidence of PE, 37.5%). There is no role for measuring a D-dimer level in these patients, as a normal D-dimer level does not adequately rule out PE. 

The American College of Physicians recommends the following algorithm for evaluating patients with suspected PE using the different clinical guidelines.

Pathway for the Evaluation of Patients with Suspected PE

CURB-65 Score for Pneumonia Severity

This clinical guideline was assigned to determine the disposition of the patient by estimating the mortality of community-acquired pneumonia.

A score of 0–1: outpatient care
A score of 2–3: inpatient or observation admission
A score of >3: inpatient admission with consideration for ICU for the score >4

CURB-65 Criteria

• Confusion (+1)

• blood Urea nitrogen (BUN) >19 mg/dL (+1)

• Respiratory rate ≥30 (+1)

• systolic BP <90 or diastolic BP ≤60 (+1)

• age ≥65 (+1)

Abdomen

Alvarado Score for Acute Appendicitis

The Alvarado Score is used to determine the likelihood of appendicitis in patients with suspected appendicitis.

A score ≤3: rules out appendicitis and generally does not warrant CT for diagnosis
A score of 4–6: indicates that CT will help differentiate the diagnosis
A score ≥7: highly suggestive of appendicitis and prudent to involve early surgical consultation

Alvarado Score criteria:

• right lower quadrant tenderness (+2)

• elevated temperature (37.3°C or 99.1°F) (+1)

• rebound tenderness (+1)

• migration of pain to the right lower quadrant (+1)

• anorexia (+1)

• nausea or vomiting (+1)

• leukocytosis >10,000 WBC/mm³    (+2)

• leukocyte left shift (+1)

*

Ranson Criteria for Pancreatitis Mortality*

A Ranson score estimates mortality in patients with acute pancreatitis. It has two parts; as ED providers, you calculate the first part while the second part is not included.

A score ≤2: severe pancreatitis unlikely, low risk for mortality
A score ≥3: severe pancreatitis likely, consider ICU care

Ranson Score criteria

• age >55 (+1)

• glucose >200 mg/dL(+1)

• WBC >16,000 mm³ (+1)

• AST >250 (+1)

• LDH >350 (+1)

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