MONA: Morphine, Oxygen, Nitroglycerin and Aspirin
Acute coronary syndrome is characterized by symptoms of myocardial ischemia. The condition can be life-threatening and requires immediate medical attention. One of the main symptoms associated with acute coronary syndrome is chest pain. Pain can also radiate to the arms, jaw, back and sometimes the teeth. Although not a hard and fast rule, the severity of symptoms will sometimes correlate with the degree of occlusion in the arteries. Additional symptoms of acute coronary syndrome may include nausea, shortness of breath and diaphoresis, as well as apprehension or a sense of impending doom.
MONA is an acronym used to help medical professionals remember the initial treatment for acute coronary syndrome. MONA stands for morphine, oxygen, nitroglycerin and aspirin (“MONA greet chest pain patients at the door”). It is important to understand that the acronym represents the steps in treatment, but not necessarily the order in which they are administered.
The ‘M’ in MONA stands for morphine. Morphine is administered to patients with acute coronary syndrome to decrease pain when pain is not resolved with nitroglycerin. Although doses may vary according to physician preference, generally small doses are administered more often, rather than large doses that are spread out i.e. 2-4 mg of morphine given IV push every five to 15 minutes.
One of the classic symptoms of acute coronary syndrome is chest discomfort or pain which can vary from mild to severe. When a person experiences significant pain, anxiety is usually quick to follow. Chest pain may cause a patient to believe they are having a heart attack, which will also increase anxiety. Morphine can be helpful in relieving both pain and anxiety.
Morphine binds to opiate receptors in the brain, which decreases the perception of pain. It also has a calming effect on a person, decreasing their emotional response to pain.
Patients who are administered morphine should be monitored closely to determine their reaction to the medication. Pain level should be accessed, as well as blood pressure. Since morphine often has a sedating effect, it can depress respiratory drive significantly. Respiratory status should be continually monitored, along with pulse oximetry. Additional side effects which can occur after giving morphine include dizziness, nausea, dry mouth, drowsiness and headache. Caution should be used when administering morphine to patients with right-sided heart failure or patients with inferior MI, as hypotension may occur and can be severe. If possible, a 12-lead ECG should be obtained to rule out an inferior MI.
Oxygen administration is also part of MONA. When blood flow is decreased to the heart in acute coronary syndrome, a portion of the heart is deprived of oxygen. Supplemental oxygen may be administered as part of the initial treatment for acute coronary syndrome in order to improve oxygenation of the ischemic heart tissue.
According to the American Heart Association, there is not sufficient evidence to support the benefits of using oxygen in uncomplicated acute coronary syndrome. However, it is often administered during the initial assessment. In patients who are short of breath, have signs of heart failure or are hypoxic (SPO2 ≤ 94%), oxygen should be administered.
Oxygen can be administered through a nasal cannula or mask. According to the AHA, oxygen levels equal to or greater than 94 percent are usually acceptable. In addition to monitoring a patient’s oxygen level with pulse oximetry, it is important to be aware of signs of hypoxemia, such as confusion and cyanosis.
Be aware that oxygen can only be delivered through a low flow nasal cannula up to six liters per minute. High flow nasal cannulas, which may be used in a hospital setting, can deliver much higher flow rates depending on the manufacturer. Simple masks and non-rebreather masks are additional options used to administer higher levels of oxygen.
Another medication used which is part of the initial treatment for acute coronary syndrome is nitroglycerin. Nitroglycerin is used to decrease chest pain and may be administered as soon as pain starts. It causes arterial and venous dilatation, which decreases the workload of the heart and reduces myocardial oxygen demand.
Nitroglycerin may be administered in different forms. For example, it may be given in the form of sublingual tablets at a dose of 0.3 mg to 0.4 mg every five minutes for up to three doses. Nitroglycerin also comes in a spray form. One to two sprays every five minutes up to three times may also be administered. Nitroglycerin should not be given to patients with a systolic blood pressure of less than 90 mm Hg.
Aspirin is also part of the initial treatment for acute coronary syndrome. Aspirin is used to prevent further clot formation by decreasing platelet aggregation. According to the AHA, 160 to 325 mg of aspirin should be administered. If possible, the aspirin should be chewed to allow for faster absorption. Some possible contraindications to aspirin therapy includes a bleeding disorder, active peptic ulcer disease and hepatic disease.
O’Connor, R. 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Acute Coronary Syndromes. Circulation. 2010. http://circ.ahajournals.org/content/122/18_suppl_3/S787.full Accessed September 2014.
Overbaugh, K. MSN, RN. Acute Coronary Syndrome. The American Journal of Nursing. 2009; 109(5). http://www.ucdenver.edu/academics/colleges/nursing/Documents/PDF/coronary-syndrome.pdf Accessed September 2014.