Arterial pressure monitoring is a form of invasive blood pressure monitoring and is done through the cannulation of a peripheral artery. Hemodynamic monitoring is important in the care of any hospitalized patient. Frequent monitoring is of utmost importance in critically ill patients and surgical patients with an increased risk of morbidity and mortality. This can be achieved through intermittent monitoring, which is non-invasive but only provides snapshots in time, or by continuous invasive monitoring.
The most common way to do this is arterial pressure monitoring via the cannulation of a peripheral artery. Each cardiac contraction exerts pressure, which results in mechanical motion of flow within the catheter. The mechanical motion is transmitted to a transducer via a rigid fluid-filled tubing. The transducer converts this information into electrical signals, which are transmitted to the monitor. The monitor displays a beat-to-beat arterial waveform as well as numerical pressures. This provides the care team with continuous information about the patient’s cardiovascular system and can be used for diagnosis and treatment.
The most common site of arterial cannulation is the radial artery due to ease of accessibility. Other sites are the brachial, femoral, and dorsalis pedis artery.
For the following patient care scenarios, an arterial line would be indicated:
①Critically ill patients in the ICU who require close monitoring of hemodynamics. In these patients, blood pressure measurements at spaced out intervals may be unsafe as they may have sudden changes in their hemodynamic status and require timely attention.
②Patients being treated with vasoactive medications. These patients benefit from arterial monitoring, allowing the clinician to titrate the medication to the desired blood pressure effect safely.
③Surgical patients at increased risk of morbidity or mortality, either because of preexisting comorbidities (cardiac, pulmonary, anemia, etc.) or because of more complicated procedures. These include but are not limited to neurosurgical procedures, cardiopulmonary procedures, and procedures in which a large volume of blood loss is anticipated.
④Patients who require frequent lab draws. These include patients on prolonged mechanical ventilation, which necessitates an analysis of arterial blood gas for titration of vent settings. The ABG also allows for monitoring hemoglobin and hematocrit, treatment of electrolyte imbalances, and evaluating a patient’s responsiveness to fluid resuscitation and administration of blood products and calcium. In these patients, the presence of an arterial line allows a clinician to easily obtain a sample of blood without having to stick the patient repeatedly. This minimizes patient discomfort and decreases the infection risk as the integrity of the skin does not need to be violated with each lab draw.
While arterial blood pressure monitoring can provide invaluable information, arterial cannulation is not routine patient care. It is not required for every patient in the ICU or every patient undergoing surgery. For certain patients, the cannulation of an artery is contraindicated. These include infection at the site of insertion, an anatomic variant in which collateral circulation is absent or compromised, the presence of peripheral arterial vascular insufficiency, and peripheral arterial vascular diseases such as small to medium vessel arteritis. Additionally, while not absolute contraindications, careful consideration should be made in patients who have coagulopathies or take medications that prevent normal coagulation.
Post time: Sep-28-2023
