Invasive blood pressure is a highly accurate and continuous blood pressure measurement provided through a catheter inserted into a patient’s artery. Several arteries can be used as insertion sites and this option may be recommended for an unstable patient in the hospital. This technique is widely considered a gold standard because of the high degree of accuracy when compared to non-invasive, also known as indirect, methods like applying a blood pressure cuff. It can also carry some risks which may be considered before implementing it for a given patient.
In situations where invasive blood pressure monitoring is appropriate, a medical provider inserts a catheter into an artery, making sure it is clearly labeled as an arterial catheter. It is attached to a length of tubing which connects to a container of saline. As the pressure in the line changes in response to the heartbeat, a diaphragm records the changes and generates a waveform of the patient’s blood pressure. Beat by beat, medical providers can monitor for changes and spot irregularities.
Direct measurement of blood pressure allows for very accurate monitoring, which can be important in a patient who is not medically stable. A doctor may recommend invasive blood pressure to monitor minute changes during treatment, especially if the procedure is likely to cause spikes or falls in blood pressure. Patients in intensive care may be monitored with this technique as well because of the superior accuracy, and because repeat measurements with a cuff can be irritating and may potentially damage the soft tissue.
Placement of a catheter in an artery also provides a convenient point to take blood samples for the purpose of arterial blood gases and other tests. Critically ill patients may need regular blood tests for monitoring purposes and it can be safer to take them from a fixed catheter than to insert a new needle every time. One potential risk is that someone could mistakenly inject medications into the catheter, which could cause severe complications because drugs are intended for intravenous, not arterial, delivery.
Other concerns with invasive blood pressure can include risks of infection and clotting as a result of the catheter insertion, especially if it needs to be left in place for a long time. Medical practitioners may monitor the site for signs of complications so they can intervene if a problem develops. They check for issues like heat, redness, and swelling that might indicate the patient has inflammation. Keeping the site clean and dry also helps prevent problems associated with invasive blood pressure monitoring.