This series will focus on working through the differential diagnosis for the 3 most common causes of 911 services activation; those causes being:
Acute Chest pain
Shortness of breath
Abdominal pain
Developing a differential diagnosis, and using history, physical assessments, and vital signs, to reach a working field diagnosis, are skills that every paramedic needs to be proficient in. If we don't know what the problem is, then we can't help our patients. So, without further delay, lets look at how we work through the differential for a patient complaining of chest pain.
Obviously, upon patient contact our initial priorities remain the same regardless of the nature of the 911 call. We need to assess LOA, open and maintain the airway, assess respirations and address respiratory distress with oxygen, or respiratory failure with ventilation, control bleeding, and assess circulatory status.
Once we have completed our primary assessment and mitigated any life threats, we need to determine what we think is going on with our patient. To do this we start with the chief complaint. In this case we are discussing chest pain. There are a variety of potential causes of chest pain, most of which are benign, however, this is EMS and our job is to rule out life threats. In order to do this, we need to have a differential diagnosis (list) containing 4-5 of the most deadly causes of chest pain, that we cannot afford to miss. We can then use our history questions, physical examination, and vital signs to rule-in, and rule-out, the possible causes of the patient's chest pain. The mnemonic P.A.P.P.A. Gives us a good way to remember the potentially lethal causes of chest pain:
P= Pulmonary Embolism
A= Acute Coronary Syndrome (STEMI/NSTEMI)
P= Pneumothorax/Pneumonia
P= Pericarditis
A= Aortic Dissection
By keeping these potential causes in mind, we can use our history taking questions to start to narrow the differential. We can start with a general SOCRATES history, to start the process:
Site: Where is the pain located? If the pain is well localized, or diffuse/poorly localized, we can start to differentiate potential causes.
Well Localized
Pulmonary embolism
Pneumothorax
Aortic dissection
Poorly localized
ACS
Pericarditis
Pneumonia
We can further narrow the differential by looking at where the pain occurs on the chest:
PE: Generally can occur anywhere, but is usually not centrally located, as the occlusion occurs in the pulmonary artery of the affected lung.
ACS: Classically, pain is felt centrally, or just left of centre, retrosternal.
Pneumothorax: Pain will be felt on the affected side, and is usually in the lateral chest wall.
Pneumonia: Pain is generally diffuse across the entire chest wall.
Pericarditis: Pain is typically retrosternal, central, or epigastric.
Aortic dissection: Pain is typically central chest, directly behind the sternum.
Now that we have looked at the site of the pain for clues, we can move on to the:
Onset: we want to know if the pain came on suddenly or gradually, and what the patient was doing when it started. -PE: Usually has a gradual onset, typically beginning with shortness of breath, and developing into pain over a short period of time. -ACS: The onset may be sudden or gradual, however pain generally starts out mild and reaches maximal intensity over a period of time. -Pneumothorax: Usually pain is sudden and severe. -Pneumonia: Pain usually develops over several hours to days. -Pericarditis: Pain typically has a gradual onset. -Aortic dissection: Sudden onset at maximal intensity.
Next we look at:
Character: What does the pain feel like? -PE: Usually described as sharp or stabbing. -ACS: Typically “crushing”, “Squeezing”, “heavy”, “Pressure” -Pneumothorax: Sharp, squeezing. -Pneumonia: Sharp or burning -Pericarditis: Burning or pressure -Aortic dissection: Ripping, tearing, or stabbing pain.
Then we move to:
Radiation: -PE: Generally does not radiate. -ACS: commonly radiates to either arm, the shoulder, jaw, or back. -Pneumothorax: No radiation usually. -Pneumonia: Usually the entire chest. -Pericarditis: May follow similar pattern to that of ACS. -Aortic dissection: Often felt in the mid scapula as well.
Associated symptoms: -PE: Severe dyspnea, hemoptysis, Syncope, hypoxia, recent history of surgery, long travel, or prolonged immobility, or other risk factors such as cancer, birth control, pregnancy, or age >65 years. -ACS: dyspnea, nausea, diaphoresis, weakness, existing cardiac risk factors including: DM, HTN, Smoking, High Cholesterol, or family history of MI. -Pneumothorax: Dyspnea, hypoxia, dizziness -Pneumonia: Fever, chills, productive cough, weakness -Aortic dissection: Stroke-like symptoms if carotid affected, lower limb weakness, dizziness, altered LOA (particularly if tomponade develops), pulse deficits
Timing: Is the pain constant or does it come and go? -PE: Pain is generally constant. -ACS: Pain is constant. -Pneumothorax: Pain may come and go. -Pneumonia: Generally intermittent. -Pericarditis: Constant -Aortic dissection: Pain is constant.
Exacerbating factors: What provokes the pain? -PE: Deep inspiration or coughing tend to worsen pain, as does lying down. -ACS: Pain is generally not affected by position, palpation, or insipiration. -Pneumothorax: Inspiration may worsen pain. -Pneumonia: Inspiration and coughing. -Pericarditis: lying flat, or chest wall palpation. -Aortic dissection: Deep inspiration against restricted chest wall movement (hands on either side of chest wall) increases intrathoracic pressure. Generally this will worsen pain in aortic dissection. Lying flat way also increase pain.
Severity: Pain is subjective, and the degree of pain is generally not helpful as a diagnostic tool here.
Once we have collected a history, we usually have narrowed down the differential to 1-3 problems that could be occurring. We can now further ask any clarifying questions if needed, such as:
Do you have a history of blood clots, pulmonary embolism?
Do you have a family history of heart problems or heart attacks?
Have you had any recent infections, fevers, chills, or exposure to potential infectious agents?
Do you have any history of aneurysm, or connective tissue disorders? Has anyone in your family been diagnosed with these issues?
To further clarify things we need to perform a physical assessment and obtain vital signs including a 12-lead ECG. As far as our physical goes we want to:
Palpate the abdomen, to rule out referred pain from gastrointestinal causes.
Palpate the chest wall.
Auscultate the chest
Assess for JVD, or peripheral edema/ascites
Inspect and palpate the back for potential spinal root nerve causes of pain
We can then examine the 12-lead for:
ST-Segment elevation
T-Wave abnormalities
Dysrhythmia
AV Blocks
Bundle Branch blocks
Abnormal heart rate
Reciprocal changes indicating ischemia
We also want to look at our vitals for clues as to what is going on. Remember, the patient's complaint must be investigated globally, taking all of our data into consideration.
Now that we know the process, lets use an example to demonstrate it.
You are called to attend to a 67 year old male complaining of chest pain. On arrival you are greeted by the patient's spouse who directs you to the garage, where the patient is located, seated on a folding chair. The patient is alert, tracks you with his eyes as you approach, and appears pale and diaphoretic. He is leaning forward, clutching his right side chest. After assessing your ABCs. You obtain a history of present illness, which reveals the following.
Fred, was in his garage moving boxes from the floor to a shelf on the wall, when he suddenly became short of breath and had to sit down. He tells you that he had the sudden onset of severe right lateral chest wall pain, that feels sharp and constricting, and does not radiate. He complains of associated shortness of breath, and lightheadedness. The pain is stated to be constant, but is exacerbated by deep inspiration and palpation. He rates it at 8/10 at rest and 10/10 with inspiration.
So, right from the start, we know that the pain is right, lateral, chest wall. PE is a possibility, as is pneumothorax. ACS does not generally present this way, nor does pneumonia, pericarditis, or aortic dissection. The onset was stated to be sudden, which also fits with our 2 potential causes. The pain is described as sharp, which also fits well with PE or pneumothorax. Associated symptoms including shortness of breath and lightheadedness could also fall into either category. The pain is constant but pleuritic in nature, which again fits with both.
At this point, some clarifying questions can help us.
When asked about recent surgery, travel, or immobility, Fred denies any history over the past 6 months. He also denies any recent history of lower leg pain or swelling, and has no known history of blood clots. Fred's medical history does reveal that he is a smoker, with a history of COPD.
From this history we can be reasonably certain that Fred is not experiencing a pulmonary embolism, however physical and vitals will still be needed. At this point, a history of known lung disease, and a continued smoking history may lead us to suspect pneumothorax.
Palpation of the abdomen reveals nothing remarkable. Fred does exhibit chest wall tenderness on the affected side, and auscultation does reveal diminished breath sounds on the right, with no other adventitious sounds noted. The 12-lead ECG is unremarkable, with the exception of atrial fibrillation, which Fred acknowledges is a known condition. The rest of the vitals are as follows:
HR 78 Irregular
RR 24 Shallow
BP 145/77mmHg
GCS 15
Temperature 37.1 degrees celsius
SPO2 89% on room air, corrected to 92% on 2LPM nasal cannula
ETCO2 50mmHg
Based on the vitals and the results of the physical we can narrow or differential from PE to pneumothorax with confidence. From here we can move Fred to the ambulance, start an IV at KVO, and reassess our ABCs, before transporting to the ED.
So, as you can see above, we can use the tools we have, to accurately narrow from a generalized complaint of chest pain, to a focused problem; in this case pneumothorax. Once we know what we are dealing with, we can develop an appropriate treatment plan, and initiate transport to the correct facility.
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