Arterial cannulation with continuous pressure transduction allows for moment-to-moment monitoring of blood pressure changes. In addition, it permits detection of intraoperative hypotension earlier than indirect monitoring techniques and provides reliable vascular access for blood sampling. Invasive arterial blood pressure monitoring allows pressure monitoring in situations when noninvasive blood pressure monitoring is not possible, such as during nonpulsatile cardiopulmonary bypass. Invasive monitoring also allows for the analysis of arterial pressure waveforms, which can be utilized to better understand clinical scenarios. However, invasive monitoring is not without its disadvantages: it requires technical expertise; it is costly; and it has the potential for serious complications when compared to noninvasive techniques.
Indications for invasive arterial blood pressure monitoring include:
Induced, on-going or anticipated hypotension, or wide variations in blood pressure
End-organ disease requiring precise pressure regulation
The need for frequent or multiple blood gas measurements
The need for continuous monitoring of cardiac output and stroke volume, where the placement of a pulmonary artery catheter is impractical
Situations when noninvasive methods of blood pressure monitoring are unreliable or difficult, such as with burns, trauma, or dysrhythmias
A few absolute contraindications to invasive pressure monitoring exist. Catheterization should be avoided in smaller end-arteries with inadequate collateral blood flow. To prevent ischemia, invasive monitoring should also be avoided in extremities with suspected or preexisting vascular insufficiency.
Complications associated with arterial cannulation include hematoma formation, thrombosis with distal ischemia, air or catheter embolism, blood loss, arterial drug administration, vasospasm, pseudoaneurysm, systemic infection, and inadvertent nerve damage or damage to adjacent structures. However, data suggest that the majority of complications can be attributed to equipment misuse, such as incorrect calibration or incorrect interpretation of the pressure display. Overall, there is a very low incidence of long-term complications associated with invasive arterial blood pressure monitoring. For example, the risk of distal ischemia is estimated to be less than 0.1%.
There are several risk factors that can potentially contribute to complications with arterial cannulation, including prolonged cannulation, repeated insertion attempts, high-dose vasopressor administration, and the use of large-bore catheters. Additional risk factors include hyperlipidemia, anticoagulation, vasospastic arterial disease, previous arterial injury, thrombocytosis, and protracted shock.
Several steps can be taken to minimize the risk of complications. Small catheters and continuous saline infusion at 2–6 mL/h help reduce the risk of thrombosis and disruption of the arterial wall. Using flexible guidewires may reduce the risk of traumatic cannulation, especially in tortuous vessels. Monitoring with a pulse oximeter on the ipsilateral side of the catheter helps to detect decreased perfusion to distal tissues. Additionally, minimizing the cannulation time and insertion attempts, and limiting flushing can help to decrease complication rates. Finally, an aseptic technique and early discontinuation of unnecessary catheters reduces ...