Overview
Definition:
Arterial line insertion is a procedure to cannulate an artery, typically the radial artery, to provide continuous, real-time invasive arterial blood pressure monitoring
It also allows for frequent arterial blood gas sampling.
Epidemiology:
Arterial lines are widely used in critically ill patients in ICUs and during major surgical procedures
Radial artery cannulation is the most common site due to its accessibility, superficial location, and collateral circulation via the ulnar artery
Complication rates are generally low when performed correctly.
Clinical Significance:
Continuous arterial blood pressure monitoring is crucial for managing hemodynamically unstable patients, titrating vasoactive medications, and guiding fluid resuscitation
Arterial blood gas analysis provides essential information on oxygenation, ventilation, and acid-base status, guiding critical care decisions
In surgical contexts, it aids in monitoring for intraoperative hypotension or hypertension and assessing tissue perfusion.
Indications
Indications For Insertion:
Hemodynamic instability requiring frequent blood pressure monitoring
Need for frequent arterial blood gas sampling
Titration of vasoactive or vasopressor drugs
Procedures with significant risk of hemodynamic fluctuations (e.g., major vascular surgery, cardiac surgery)
Induced therapeutic hypothermia
Patients with severe hypertension or hypotension
Arterial waveform analysis for dynamic preload responsiveness assessment.
Contraindications:
Absence of palpable pulse at the insertion site
Local infection or skin lesion at the insertion site
Significant peripheral vascular disease or occlusive disease in the limb
Coagulopathy or anticoagulation therapy (relative contraindication, assess risk vs
benefit)
Previous arterial surgery or bypass at the insertion site
Arteriovenous fistula in the ipsilateral limb.
Site Selection:
The radial artery is preferred due to its superficial location, collateral circulation via the ulnar artery, and low risk of nerve damage
Other sites include the brachial, femoral, and dorsalis pedis arteries, each with specific advantages and disadvantages.
Preoperative Preparation
Patient Assessment:
Assess patient's coagulation status (PT/INR, PTT)
Review platelet count
Identify allergies
Assess for contraindications
Explain the procedure and obtain informed consent.
Equipment Gathering:
Sterile gloves, gown, mask
Antiseptic solution (e.g., chlorhexidine)
Sterile drapes
Local anesthetic (e.g., lidocaine 1-2%) with syringe and needle
Arterial line kit: typically includes a 20-22 gauge Teflon-over-needle catheter, guidewire, introducer sheath (optional), flush bag with heparinized saline, pressure tubing, transducer, and monitor connection
Suture material for securement.
Allen Test:
Perform the modified Allen's test to ensure adequate collateral circulation from the ulnar artery
Occlude both radial and ulnar arteries, have the patient make a fist, then release pressure on the ulnar artery while maintaining pressure on the radial
The palm should flush pink within 5-15 seconds, indicating good ulnar artery patency and collateral flow
Failure to flush suggests inadequate collateralization and contraindicates radial artery cannulation on that side.
Procedure Steps
Aseptic Technique:
Perform hand hygiene
Don sterile gloves, gown, and mask
Prepare the insertion site with antiseptic solution using concentric circles from the center outwards
Apply sterile drapes.
Local Anesthesia:
Infiltrate the skin and subcutaneous tissue overlying the palpated radial artery with local anesthetic
Avoid injecting directly into the artery.
Catheter Insertion:
Palpate the radial artery with the non-dominant hand to stabilize it
Insert the arterial catheter (typically 20-22 gauge) at a 30-45 degree angle through the skin directly over the artery, aiming towards the palpable pulse
Look for pulsatile flashback of bright red blood into the catheter hub, indicating arterial entry
Once blood enters, advance the catheter slightly and then advance the catheter while withdrawing the needle
If using a Seldinger technique, advance the guidewire through the catheter, remove the catheter, and thread the new catheter over the guidewire.
Securing The Line:
Once arterial pulsatile flow is established through the catheter, gently advance the catheter fully
Secure the catheter hub to the skin with sutures and/or sterile dressing
Connect the arterial line tubing to the transducer and flush system
Ensure the line is securely connected to prevent dislodgement.
Confirmation Of Placement:
Confirm arterial waveform on the monitor
The waveform should be sharp and pulsatile with clear systolic upstroke and dicrotic notch
Blood samples should be bright red and pulsatile
Check for distal perfusion and sensation in the hand to ensure no occlusion or nerve compromise.
Postoperative Care And Monitoring
Hemodynamic Monitoring:
Continuously monitor arterial blood pressure (systolic, diastolic, mean arterial pressure - MAP)
Observe the arterial waveform for changes that may indicate hypovolemia, vasodilation, vasoconstriction, or dysrhythmias
Calibrate the transducer to the level of the phlebostatic axis.
Blood Sampling:
Collect arterial blood gases (ABGs) and other laboratory samples as needed
Ensure proper technique for sample collection to avoid air bubbles or venous admixture
Discard the initial aliquot of blood to prevent heparin contamination if heparinized saline is used for flushing.
Site Care:
Inspect the insertion site regularly for signs of bleeding, hematoma, infection, or thrombosis
Dress the site with a sterile transparent semipermeable dressing and change it according to hospital policy
Avoid excessive manipulation of the line.
Limb Perfusion Assessment:
Assess distal perfusion, sensation, and motor function of the cannulated limb at regular intervals
Check capillary refill, skin color, temperature, and presence of pulses distal to the insertion site.
Complications
Early Complications:
Hemorrhage and hematoma formation at the insertion site
Artery spasm
Accidental venipuncture
Nerve damage
Thrombosis leading to occlusion
Pain at the insertion site
Infection.
Late Complications:
Arterial occlusion and limb ischemia (rare with radial artery due to collateral flow)
Pseudoaneurysm formation
Arteriovenous fistula (rare)
Infection progressing to sepsis
Embolization of thrombus or plaque.
Prevention Strategies:
Perform a thorough Allen's test
Use the smallest gauge catheter appropriate for the indication
Secure the line meticulously to prevent dislodgement
Maintain strict aseptic technique during insertion and site care
Use heparinized flush solution judiciously
Monitor distal perfusion regularly
Remove the line as soon as it is no longer indicated.
Key Points
Exam Focus:
The modified Allen's test is critical for radial artery cannulation
Continuous MAP monitoring is essential in unstable patients
Common complications include hematoma, thrombosis, and infection
Radial artery is preferred due to collateral circulation.
Clinical Pearls:
Stabilize the artery firmly before insertion to prevent multiple punctures
A good pulsatile flashback is key to confirming arterial entry
Secure the line meticulously
dislodgement is a common issue
Always assess distal perfusion after insertion and regularly thereafter.
Common Mistakes:
Failing to perform or misinterpreting the Allen's test
Incorrect angle of insertion leading to subcutaneous puncture
Failure to adequately stabilize the artery
Inadequate securement of the line
Over-reliance on arterial waveform without considering clinical context
Prolonged indwelling time without clear indication.