Hats off to Bob Peterson for the best response to this month’s scenario. Bob correctly identified the right BLS treatment including withholding oxygen based on current AHA guidelines. Bob also identified some “must not miss” diagnoses in addition to cardiac chest pain. Nicely done!
Last week we presented the scenario of a 57-year-old overweight male who experienced an onset of chest pain while mowing his lawn. His pain did not subside when he stopped his activity and did not respond to taking his own nitroglycerin. The 911 call taker had advised him to take aspirin prior to your arrival, which he did.
Assessment
There are generally considered to be two types of angina (chest pain): stable and unstable. Stable angina usually occurs with an increased level of physical activity when the heart has to work harder than usual.
Often, stable angina is anticipated and patients are able to see a pattern in their symptoms. Stable angina often resolves with rest or after taking medications (like nitroglycerine). Stable angina can be caused by a narrowing of the coronary arteries that worsens over time.
Unstable angina is abnormal for the patient. While it often begins when at rest, it may be characterized by pain, which does not improve when an increased level of activity is stopped.
Additionally, unstable angina often does not respond to medication. As indicated by its rapid onset and unusual quality, unstable angina is often caused by a new blood clot that suddenly blocks a coronary artery. This decreases the flow of oxygenated blood in the heart and eventually results in the death of cardiac tissue.
Treatment
Because Frank’s pain is different than normal, came on suddenly and did not respond to rest or medication, it seems likely that he is experiencing unstable angina. Because the suspected underlying cause of his pain is a blood clot in a coronary artery, taking aspirin early is extremely important.
Aspirin decreases platelet aggregation and can keep a clot in the heart from getting bigger. Because of its importance in treating heart attack many EMS systems are advising patients to take an aspirin when they call 911.
The acronym that many EMS providers learn when treating chest pain is MONA, which stands for morphine, oxygen, nitroglycerin and aspirin. Obviously, with a BLS ambulance, morphine is not an option in this case. And, the patient has already taken aspirin.
What about nitroglycerin?
Nitro is light sensitive and is usually packaged in dark-colored containers to protect it. Additionally, patients may not check the expiration date before taking a nitro tablet when they have an onset of chest pain.
Taking an expired tablet may not cause any harm to the patient but it may not treat his symptoms either. Some EMS systems allow EMTs to assist a patient in taking his or her own medication (like nitro), but before doing so, the EMS provider should check to ensure that the medication has not expired.
In the case of Frank, that his pain did not respond to medication may be a result of his underlying heart disease, or it may be as simple as the fact that his nitro is expired.
Oxygen has been a go-to medication for EMS providers for many years. The first two steps in our assessment and care of patients are airway and breathing after all.
Not so long ago, EMS providers put many patients on supplemental oxygen under the mistaken impression that it couldn’t hurt.
Recently however, the wisdom of that assumption is being questioned. Researchers are finding that for many groups of patients, outcomes are actually worse when oxygen is given in excess.
The mechanism of harm is thought to be linked to oxidative stress, which is a result of the reactivity of oxygen and the ability of free radicals to damage cells in the body.
In the last release of guidelines, the American Heart Association modified its recommendations for application of oxygen to patients suffering from acute coronary syndrome (ACS).
Rather than place all chest-pain patients on oxygen, the AHA now states that there is not evidence to support the “…routine use (of oxygen) in uncomplicated ACS.”[1] The guideline goes on to state that in patients who are short of breath as well, oxygen may be administered until pulse oximetry is 94 percent or above.
Ultimately, patients with chest pain need to have a 12 lead ECG performed and, if they are having an acute myocardial infarction, need to be transported to a hospital with the ability to perform a cardiac catheterization.
Outcome
After checking Frank’s nitroglycerine you find that it expired over one year ago. Since the medication is too old, you elect to withhold additional nitro.
Additionally, since Frank’s pulse-ox is above 94 percent, you do not administer oxygen. While waiting for ALS to arrive, you continue to monitor Frank’s vital signs and find no changes.
The ALS unit arrives and the paramedic immediately performs a 12 lead ECG which shows an acute MI. The patient is loaded into the ambulance and the paramedic joins your unit while you transport to the hospital.
En route, the medic places an IV and gives nitroglycerine, which provides some relief to Frank’s pain. After approximately 10 minutes, you arrive in the ED. The staff from the cath lab have been advised of your arrival and meet Frank in the code room.
Frank was taken to the cardiac cath lab immediately out of the ER. He was found to have a total occlusion of two branches of his coronary arteries. After the arteries were opened two stents were placed.
Frank made a quick recovery and was discharged home which an appointment to undergo cardiac rehabilitation.
References
1. O’Connor, Robert E., William Brady, Steven C. Brooks, Deborah Diercks, Jonathon Egan, Chris Ghaemmaghami, Venu Menon, Brian J. O’Neil, Andrew H. Travers, and Demtris Yannopoulos. “Part 10: Acute Coronary Syndromes: 2010 American Heart Association Care Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular.” Circulation 122(2010): S787-S817.
