The call comes in as “difficulty breathing.”
You arrive to find a patient sitting upright, breathing fast, scared, clutching heir chest. Lung sounds are clear. Oxygen saturation is 97%. Blood pressure is stable. Heart rate is elevated but not shocking.
Someone says, “She’s been really anxious today.”
The working diagnosis settles in fast: hyperventilation.
The crew stays on scene coaching slow breathing. Reassurance continues. Minutes pass. Nothing changes.
And that’s the moment we need to stop and ask a harder question.
What if this isn’t anxiety?
What if this is a pulmonary embolism quietly declaring itself while we’re trying to calm it down?
| MORE: Recognizing pulmonary embolism: Key indicators
Hyperventilation: A dangerous assumption
Hyperventilation is common in EMS. Pulmonary embolism (PE) is not.
That imbalance creates risk. Experience teaches us to recognize what we see often. But PE is one of those diagnoses that punishes familiarity.
Pulmonary embolism remains a major cause of sudden morbidity and mortality, and delayed diagnosis is still a significant contributor to poor outcomes [1].
We don’t miss PE because we don’t care.
We miss it because it looks ordinary at first.
Why pulmonary embolism is easy to miss
PE rarely presents dramatically in the early phase.
Many patients have:
- Clear lung sounds
- Near-normal oxygen saturation
- Anxiety and air hunger
- Persistent tachypnea
Studies of confirmed pulmonary embolism cases show that hypoxemia may be absent early, and clinical presentations vary widely [2].
That air hunger is not psychological. It’s physiologic. The embolism blocks perfusion, increases dead space, and drives respiratory compensation. The patient breathes faster because their body is trying to survive.
Anxiety is often the result, not the cause.
Hyperventilation vs. pulmonary embolism: Deciding factors
No single sign separates hyperventilation from pulmonary embolism. Patterns do.
Patients experiencing hyperventilation usually:
- Improve with reassurance
- Have an emotional trigger
- Show gradual symptom relief
- Heart rate normalizes when breathing slows
Patients experiencing pulmonary embolism often:
- Have sudden onset without a clear trigger
- Do not improve with coached breathing
- Exhibit persistent tachypnea and tachycardia
- Experience pleuritic or vague chest pain
If the patient is not improving with reassurance, that is diagnostic information.
That is when we need to reassess.
The on-scene time trap
One of the most dangerous habits on these calls is extended scene time.
We want to fix hyperventilation before transport. We want to help. That instinct is good. But PE is not an on-scene problem. It is a transport problem.
Definitive diagnosis requires imaging and anticoagulation. Time-to-diagnosis matters. Delays increase risk of deterioration and death [1].
Transport is not abandoning care.
For pulmonary embolism, transport is care.
Ask better questions
Focused history often reveals what reassurance hides.
Ask about:
- Sudden onset vs. gradual
- Recent surgery or hospitalization
- Long travel or immobilization
- Hormone therapy or birth control
- Cancer or prior blood clots
These risk factors strongly increase the likelihood of venous thromboembolism and should raise concern when symptoms persist [2].
Curiosity saves lives.
Vital signs tell stories
Normal oxygen saturation does not rule out pulmonary embolism.
Persistent tachypnea and tachycardia matter. Trends matter more than single numbers.
If capnography is available, low end-tidal CO₂ in a tachypneic patient may reflect ventilation-perfusion mismatch rather than successful breathing control.
And when the patient does not improve with reassurance, consider diagnostic anchoring. Cognitive bias and premature closure are known contributors to missed diagnoses in emergency medicine [3].
What medics should do differently
This isn’t about fear. It’s about discipline.
Tomorrow on shift:
- Don’t label hyperventilation early
- Reassess after reassurance
- Limit scene time when symptoms persist
- Communicate PE concern to the hospital
- Trust discomfort that doesn’t resolve
Hyperventilation is a diagnosis of improvement.
Pulmonary embolism is a diagnosis of exclusion.
If the patient isn’t getting better, neither should your certainty.
Hyperventilation vs. pulmonary embolism: Final thoughts
We have all coached breathing on scene. Many times, it was the right call.
But every once in a while, the patient in front of you is not anxious. They are hypoxic at a cellular level. They are compensating. They are deteriorating.
The next time you find yourself trying to slow someone’s breathing, pause and ask one question:
Is this patient improving — or am I just hoping they will?
That answer may change the outcome.
REFERENCES
- Goldhaber SZ, Bounameaux H. (2012). Pulmonary embolism and deep vein thrombosis. The Lancet, 379(9828), 1835–1846. https://doi.org/10.1016/S0140-6736(11)61904-1
- Stein PD, Beemath A, Matta F, Weg JG, et al. (2005). Clinical characteristics of patients with acute pulmonary embolism: Data from PIOPED II. The American Journal of Medicine, 118(12), 1413–1418. https://doi.org/10.1016/j.amjmed.2005.01.060
- Croskerry P. (2013). From mindless to mindful practice — Cognitive bias and clinical decision making. New England Journal of Medicine, 368(26), 2445–2448. https://doi.org/10.1056/NEJMp1303712
