FPS Clinical Reference

Clinical snapshot

Twenty-second review

Back pain may originate from muscle, joint, disc, nerve root, vertebra, abdominal or vascular structures, infection, or malignancy.
New weakness, saddle anesthesia, bladder dysfunction, fever, severe trauma, pulsatile mass, or pain with shock requires urgent assessment.
Keep renal or abdominal disease in the differential; overlapping or concurrent illness remains possible.
For back pain, trends and combinations of findings are more informative than one isolated vital sign.

Differentials

Compare the clinical patterns

The repeated material is grouped inside each possibility. Open only the condition you need.

Serious4 conditions

Cauda equinaTime-sensitive high-risk possibility

HPI

Clarify traumatic or atraumatic; sudden/gradual; midline vs muscular.

Signs & symptoms

Neurologic loss, fever, trauma, cancer risk, or vascular signs.

Focused exam

Expose only as needed, inspect and palpate systematically, and document distal circulation, sensation, and movement; Reassess pain, swelling, perfusion, and neurologic status after movement or intervention.

Brief pathophysiology

Cauda equina may cause back pain through a time-sensitive process capable of rapid physiological deterioration.

Vital-sign pattern

What the trend may show

Possible pattern

Isolated injury may have normal observations. Serial heart rate, pressure, respiratory status, and oxygenation help identify occult hemorrhage or thoracic injury.

Heart rate (bpm)

May rise

Pain, distress, and hemorrhage can increase rate; medications can blunt it.

Blood pressure (mmHg)

May fall late

A normal pressure does not exclude compensated hemorrhage.

Respiratory rate (breaths/min)

Trend rate / effort

Tachypnea may reflect pain, thoracic injury, shock, or acidosis.

Oxygen saturation (SpO₂)

Usually preserved

Low saturation suggests thoracic injury, hypoventilation, or concurrent disease.

Front-load in the triage report

Cauda equina: Neurologic loss, fever, trauma, cancer risk, or vascular signs.
Traumatic or atraumatic?
Sudden/gradual.

Spinal infectionTime-sensitive high-risk possibility

HPI

Clarify sudden/gradual; midline vs muscular; radiation.

Signs & symptoms

Neurologic loss, fever, trauma, cancer risk, or vascular signs.

Focused exam

Reassess pain, swelling, perfusion, and neurologic status after movement or intervention; Inspect and palpate the spine and abdomen; assess lower-limb power, sensation, reflex-related function, gait, pulses, and bladder symptoms.

Brief pathophysiology

Spinal infection may cause back pain through a time-sensitive process capable of rapid physiological deterioration.

Vital-sign pattern

What the trend may show

Possible pattern

Isolated injury may have normal observations. Serial heart rate, pressure, respiratory status, and oxygenation help identify occult hemorrhage or thoracic injury.

Heart rate (bpm)

May rise

Pain, distress, and hemorrhage can increase rate; medications can blunt it.

Blood pressure (mmHg)

May fall late

A normal pressure does not exclude compensated hemorrhage.

Respiratory rate (breaths/min)

Trend rate / effort

Tachypnea may reflect pain, thoracic injury, shock, or acidosis.

Oxygen saturation (SpO₂)

Usually preserved

Low saturation suggests thoracic injury, hypoventilation, or concurrent disease.

Front-load in the triage report

Spinal infection: Neurologic loss, fever, trauma, cancer risk, or vascular signs.
Sudden/gradual.
Midline vs muscular.

FractureTime-sensitive high-risk possibility

HPI

Clarify midline vs muscular; radiation; weakness/numbness.

Signs & symptoms

Neurologic loss, fever, trauma, cancer risk, or vascular signs.

Focused exam

Reassess pain, swelling, perfusion, and neurologic status after movement or intervention; Inspect and palpate the spine and abdomen; assess lower-limb power, sensation, reflex-related function, gait, pulses, and bladder symptoms.

Brief pathophysiology

Fracture may cause back pain through a time-sensitive process capable of rapid physiological deterioration.

Vital-sign pattern

What the trend may show

Possible pattern

Isolated musculoskeletal injury often leaves central vital signs near baseline. Persistent abnormality should prompt reassessment for hemorrhage, thoracic injury, infection, or a medical cause.

Heart rate (bpm)

May rise with pain

Tachycardia can reflect pain or distress; trend after treatment.

Blood pressure (mmHg)

May rise with pain

Hypotension is not expected in an isolated minor injury.

Respiratory rate (breaths/min)

May rise with pain

Persistent tachypnea suggests more than a minor isolated injury.

Oxygen saturation (SpO₂)

Usually preserved

Desaturation suggests thoracic injury or concurrent disease.

Front-load in the triage report

Fracture: Neurologic loss, fever, trauma, cancer risk, or vascular signs.
Midline vs muscular.
Radiation?

Aortic emergencyTime-sensitive high-risk possibility

HPI

Clarify radiation; weakness/numbness; saddle anesthesia.

Signs & symptoms

Neurologic loss, fever, trauma, cancer risk, or vascular signs.

Focused exam

Reassess pain, swelling, perfusion, and neurologic status after movement or intervention; Inspect and palpate the spine and abdomen; assess lower-limb power, sensation, reflex-related function, gait, pulses, and bladder symptoms.

Brief pathophysiology

Aortic emergency may cause back pain through a time-sensitive process capable of rapid physiological deterioration.

Vital-sign pattern

What the trend may show

Possible pattern

Aortic catastrophe has no single required vital pattern. Measure pressure and pulses carefully; shock or a new inter-arm difference raises concern but may be absent.

Blood pressure (mmHg)

May be high or low

Hypertension may coexist; hypotension suggests rupture, tamponade, or malperfusion.

Heart rate (bpm)

Variable

Pain may raise rate, while medications or reflexes can blunt it.

Pulse pressure (mmHg)

Compare pulses / arms

A calculated pulse pressure is less specific than pulse deficits and appropriate bilateral BP assessment.

MAP (mmHg)

Trend perfusion

A falling MAP supports hemodynamic deterioration.

Front-load in the triage report

Aortic emergency: Neurologic loss, fever, trauma, cancer risk, or vascular signs.
Radiation?
Weakness/numbness?

Common2 conditions

MechanicalCommon presentation pattern

HPI

Clarify traumatic or atraumatic; sudden/gradual; midline vs muscular.

Signs & symptoms

Movement-related pain, paraspinal tenderness, or dermatomal symptoms may support the pattern.

Focused exam

Expose only as needed, inspect and palpate systematically, and document distal circulation, sensation, and movement; Reassess pain, swelling, perfusion, and neurologic status after movement or intervention.

Brief pathophysiology

Mechanical may explain the presenting symptoms through a common clinical mechanism, while serial assessment checks for complications or an alternate cause.

Vital-sign pattern

What the trend may show

Possible pattern

Isolated injury may have normal observations. Serial heart rate, pressure, respiratory status, and oxygenation help identify occult hemorrhage or thoracic injury.

Heart rate (bpm)

May rise

Pain, distress, and hemorrhage can increase rate; medications can blunt it.

Blood pressure (mmHg)

May fall late

A normal pressure does not exclude compensated hemorrhage.

Respiratory rate (breaths/min)

Trend rate / effort

Tachypnea may reflect pain, thoracic injury, shock, or acidosis.

Oxygen saturation (SpO₂)

Usually preserved

Low saturation suggests thoracic injury, hypoventilation, or concurrent disease.

Front-load in the triage report

Movement-related pain, paraspinal tenderness, or dermatomal symptoms may support the pattern.
Traumatic or atraumatic?
Sudden/gradual.

Radicular painCommon presentation pattern

HPI

Clarify sudden/gradual; midline vs muscular; radiation.

Signs & symptoms

Movement-related pain, paraspinal tenderness, or dermatomal symptoms may support the pattern.

Focused exam

Reassess pain, swelling, perfusion, and neurologic status after movement or intervention; Inspect and palpate the spine and abdomen; assess lower-limb power, sensation, reflex-related function, gait, pulses, and bladder symptoms.

Brief pathophysiology

Radicular pain may explain the presenting symptoms through a common clinical mechanism, while serial assessment checks for complications or an alternate cause.

Vital-sign pattern

What the trend may show

Possible pattern

Isolated injury may have normal observations. Serial heart rate, pressure, respiratory status, and oxygenation help identify occult hemorrhage or thoracic injury.

Heart rate (bpm)

May rise

Pain, distress, and hemorrhage can increase rate; medications can blunt it.

Blood pressure (mmHg)

May fall late

A normal pressure does not exclude compensated hemorrhage.

Respiratory rate (breaths/min)

Trend rate / effort

Tachypnea may reflect pain, thoracic injury, shock, or acidosis.

Oxygen saturation (SpO₂)

Usually preserved

Low saturation suggests thoracic injury, hypoventilation, or concurrent disease.

Front-load in the triage report

Movement-related pain, paraspinal tenderness, or dermatomal symptoms may support the pattern.
Sudden/gradual.
Midline vs muscular.

Mimics2 conditions

RenalImportant alternative presentation

HPI

Clarify traumatic or atraumatic; sudden/gradual; midline vs muscular.

Signs & symptoms

Flank, urinary, abdominal, or systemic features suggest a non-spinal source.

Focused exam

Expose only as needed, inspect and palpate systematically, and document distal circulation, sensation, and movement; Reassess pain, swelling, perfusion, and neurologic status after movement or intervention.

Brief pathophysiology

Renal can resemble back pain through overlapping symptoms or referred physiology despite a different primary mechanism.

Vital-sign pattern

What the trend may show

Possible pattern

Isolated injury may have normal observations. Serial heart rate, pressure, respiratory status, and oxygenation help identify occult hemorrhage or thoracic injury.

Heart rate (bpm)

May rise

Pain, distress, and hemorrhage can increase rate; medications can blunt it.

Blood pressure (mmHg)

May fall late

A normal pressure does not exclude compensated hemorrhage.

Respiratory rate (breaths/min)

Trend rate / effort

Tachypnea may reflect pain, thoracic injury, shock, or acidosis.

Oxygen saturation (SpO₂)

Usually preserved

Low saturation suggests thoracic injury, hypoventilation, or concurrent disease.

Front-load in the triage report

Flank, urinary, abdominal, or systemic features suggest a non-spinal source.
Traumatic or atraumatic?
Sudden/gradual.

Abdominal diseaseImportant alternative presentation

HPI

Clarify sudden/gradual; midline vs muscular; radiation.

Signs & symptoms

Flank, urinary, abdominal, or systemic features suggest a non-spinal source.

Focused exam

Reassess pain, swelling, perfusion, and neurologic status after movement or intervention; Inspect and palpate the spine and abdomen; assess lower-limb power, sensation, reflex-related function, gait, pulses, and bladder symptoms.

Brief pathophysiology

Abdominal disease can resemble back pain through overlapping symptoms or referred physiology despite a different primary mechanism.

Vital-sign pattern

What the trend may show

Possible pattern

Isolated injury may have normal observations. Serial heart rate, pressure, respiratory status, and oxygenation help identify occult hemorrhage or thoracic injury.

Heart rate (bpm)

May rise

Pain, distress, and hemorrhage can increase rate; medications can blunt it.

Blood pressure (mmHg)

May fall late

A normal pressure does not exclude compensated hemorrhage.

Respiratory rate (breaths/min)

Trend rate / effort

Tachypnea may reflect pain, thoracic injury, shock, or acidosis.

Oxygen saturation (SpO₂)

Usually preserved

Low saturation suggests thoracic injury, hypoventilation, or concurrent disease.

Front-load in the triage report

Flank, urinary, abdominal, or systemic features suggest a non-spinal source.
Sudden/gradual.
Midline vs muscular.

Red flags

Findings that should escalate concern

New weakness, saddle anesthesia, bladder dysfunction, fever, severe trauma, pulsatile mass, or pain with shock requires urgent assessment.
Cauda equina, spinal infection, fracture, or aortic emergency: Neurologic loss, fever, trauma, cancer risk, or vascular signs.

Related medications

Medication recognition

Amoxicillin Cephalexin Doxycycline

Continue the clinical pathway

References

Clinical and academic sources

Curated clinical guidance and peer-reviewed evidence supporting this presentation. Current BCEHS guidance, medical direction, and local policy remain authoritative for practice.