The increase of medical imaging over the past few decades has brought an increase in the use of contrast media. While contrast media is usually safe there are also adverse reactions ranging from mild to life-threatening. There are two basic types of contrast reactions , anaphylactoid and nonanaphylactoid. Symptoms of a reaction can vary from chills, urticaria, seizures, etc.. Obtaining a good patient history can help check for risk factors such as asthma, previous adverse reactions, allergies, as well as, see if premedication needs to be used. The onset of a contrast reaction can range from minutes to days after the introduction of the contrast. Since some reactions can occur within minutes after the injection it is important that radiographers know not only the symptoms of reactions, but are also aware of how to treat reactions. Over the past few decades a growth in the use of medical imaging has brought along an increase in the amount of contrast media used. Contrast media is used to increase the contrast of internal organs and structures in the body. In some cases this feature is crucial for diagnosis. According to Beckett, Moriarity and Langer (2015), “Half of the approximately 76 million computed tomographic (CT) and 34 million magnetic resonance imaging (MRI) examinations performed each year include the use of intravenous contrast agents” (p. 1738). Contrast media is usually safe however, there are also adverse reactions. These reactions are generally mild but can range all the way to life-threatening. Beckett et al. (2015), also found “Authors of several recent studies have found that radiologist do not feel prepared in handling these incidents, especially the severe reactions” (p.1742). Since contrast media is used in radiography it is important for radiographers and radiologist to know the signs of a reaction and how to treat a reaction efficiently as well as feel comfortable doing so.
There are two main types of reactions, anaphylactoid and nonanaphylactoid. An anaphylactoid reaction, also know as a Idiosyncratic reaction, can be broken down into mild, moderate, and severe. These reactions mirror that of a allergic reaction. It should be noted that not everyone will experience every symptom mentioned below and may experience symptoms not mentioned. It is important that the radiographer is extremely observant and notices any changes that patient might make during the procedure. The symptoms of a mild anaphylactoid reaction include skin rash, itching, nasal discharge, nausea, and vomiting (Singh and Daftary, 2008). A moderate reactions symptoms include but is not limited to the mild reaction symptoms, edema, throat tightness or hoarseness, and wheezing with mild hypoxia. A severe anaphylactoid reaction is extremely rare but needs to be taken care of in a timely manner since some symptoms can be life-threatening. Symptoms of a severe reaction can include hypotension, laryngeal edema, anaphylactic shock, etc.. The other type of reaction is a nonanaphylactoid reaction. These reactions might also be known as physiologic reactions or chemotoxic reactions. These reactions are believe to arise from a disruption of homeostasis. Like the anaphylactoid reaction, physiologic reactions are broken down into mild, moderate, and severe. Some of the symptoms of physiologic reactions are warmth, vomiting, altered taste and in severe cases seizures.
While there is no guarantee that people will have an adverse reaction to contrast media there are some factors that might increase a person's chance of having an adverse reaction. Obtaining a good patient history can help determine if the patient has a higher risk of an adverse reaction. The physician should consider the risk and decide what is in the patients favor. Some risk factors include if the patient has had a previous reaction to contrast media, has a history of asthma, allergies, bronchospasm, diabetes, cardiac or renal disease. Other factors include age, sex, and medications. Infants and those older than 60 tend to have an increased risk (Singh and Daftary, 2008). In some cases it has been thought that patients with anxiety or who are anxious about the exam have a higher risk of an adverse reaction. It is important if the technologist notices patient anxiety they do there best to explain the procedure well and answer any questions the patient might have. In some situations premedication may be used. The point of premedication is to make a reaction that is believed to happen less severe. For example if a patient comes in for a MRI with contrast and has previously had a severe reaction to contrast before then the physician might give them medicine before the contrast to counteract the reaction. Knowing anaphylactoid reactions from physiologic reactions is important because patients with physiologic reactions do not require premedication (Beckett et al., 2015). It should be known that even in patients that are premedicated there can be a breakthrough reaction.
Almost all life-threatening contrast reactions occur within the first 20 minutes (ACR Committee, 2018). Since reactions can happen fast it is important that facilities are prepared for emergencies. Most reactions occur in the first hour after administration some as soon as 5 minutes after administration. However, in some cases there are delayed reactions that can take up to a week to occur. Delayed reactions seem to be seen more in young adults, women, and patients with an allergy history (Beckett et al., 2015). Delayed reactions occur in approximately 2% of patients and have flulike symptoms (Singh and Daftary, 2008).
When it comes to treating adverse reactions it is important to work fast and efficiently. The longer the patient goes untreated the worse the reaction can become. As soon as a reaction is suspected the administration of contrast media should be stopped immediately (Andreucci, Solomon and Tasanarong, 2014). Reactions will be treated much like an allergic reaction, physicians will use epinephrine and antihistamines in most cases. It is important that the patient is well observed and vitals are maintained in case of any sudden changes. This is extremely necessary if the patient is a child that can not express what they are feeling. For some mild reactions the physician might just observe the patient until symptoms subside whereas most moderate and severe reactions will require medication. Medications will vary depending on the severity, symptoms, and type of reaction.
If a patient is pregnant or breastfeeding they may consider waiting to have a procedure done. Contrast materials can cross through the placenta and a small amount can be excreted in breast milk. A lot is still unknown about the effect that contrast material may have on the fetus/infant. Patients should be notified of all possible risk before the procedure. Procedures using contrast should only be done if the benefits are greater than the risk and should be held off until after the postpartum period (Singh and Daftary, 2008).
Another topic worth mentioning is Contrast-Induced Nephropathy also known as CIN. This is when the use of contrast media leads to kidney dysfunction or acute renal failure. Andreucci et al. defines it as “acute renal failure occurring within 24-72 hrs of exposure to intravascular radiographic contrast media that cannot be attributed to other causes” (p. 3). CIN should be taken very seriously. It occurs especially in patients with diabetes and with preexisting renal impairment (Andreucci et al., 2014). It is important that the physician looks at the risks and benefits before deciding if the patient needs to go ahead with the procedure. If a patient with diabetes or preexisting renal impairment has to have contrast then it is critical that the doctors check their kidney function within a couple days after to make sure there is no change. According to Andreucci et al. (2014), “Several years ago it was indicated as the third leading cause of hospital-acquired acute renal failure accounting for 12% of all cases” (p.3).
Contrast media reactions are rare but still happen. Reactions can be mild, moderate, or in some cases severe. The symptoms can range from chills, hives, vomiting, seizures, hypotension, anaphylactic shock, and many more. It is important that facilities obtain a good patient history to check for factors that might increase a person's risk of having an adverse reaction. Facilities that administer contrast need to also be equipped with medication to treat adverse reactions. In some cases patients might also experience CIN which must be taken very seriously. While some reactions can be life-threatening most reactions are easily treated. The more informed technologist are with the topic the better they will be at noticing the signs and treating reactions.