II. Indications: Critically Ill Patient
- Serial Arterial Blood Gas monitoring (esp if >4 samples needed in 24 hours)
- Continuous Blood Pressure Monitoring optimized for accuracy
- Accurate systolic and diastolic Blood Pressures needed to titrated vasoactive medications
- Intracranial Hemorrhage
- Aortic Dissection
- Cardiac Arrest
- Other hemodynamic monitoring parameters may be estimated electronically (based on wave form)
III. Precautions
- Never use arterial catheters for medication or fluid infusions
- Monitor line continuously
- Alarms that would indicate open catheter (with blood loss)
- Inspect for ischemic limb or infection
- Remove catheter immediately if these occur
- Remove catheters as soon as they are no longer needed
- Must calibrate catheter and transducer first at heart level
- As with Blood Pressures in general, normal arterial pressure does not exclude hypoperfusion
- Compensatory Vasoconstriction may mask hypoperfusion until precipitous drop
- Use other measures (e.g. IVC Ultrasound for Volume Status) to further evaluate vascular status
- Abnormal pressure readings from catheter should be confirmed with manual Blood Pressure readings
- Waveform may be distorted by vascular and transducer changes
- Mean arterial pressure typically remains accurate despite waveform distortion
IV. Preparation: Arterial Line Sites (in order of preference)
- Radial artery (preferred)
- Femoral artery (requires longer catheter)
- Axillary artery (requires longer catheter)
- Dorsalis pedis artery (less reliable reading in adults)
- Avoid Brachial artery cannulation (risk of distal hand ischemia)
V. Technique: Preparation for Wrist Arterial Cannulation
- Perform Allen Test to confirm collateral circulation
- Ultrasound may also be used to demonstrate pulsatile flow in both ulnar and radial arteries
-
Heparinize syringe
- Start with 10 cc Syringe with stopcock
- Draw up 3-5 ml of Heparinized saline (50 units/ml)
- Obtain IV catheter
- Needle of 18 or 20 gauge with plastic cannula
- Flush with Heparinized saline
- Position patients wrist and hand
- Patient dorsiflexes wrist over towel pad
- Tape palm and upper Forearm to arm board
- Clean radial entry site
- Povidone-Iodine solution (Betadine) scrub
- Alcohol scrub
-
Local Anesthetic at entry site
- Small skin wheal (1-2 ml) of Lidocaine 2%
VI. Technique: Placing Arterial Line
- Identify radial artery with gentle pressure
- Needle angled 45 degrees toward arm
- Enter skin just distal to palpated artery site
- Slowly advance needle until spontaneous blood enters
- Guide wire passed into artery
- Remove needle
- Advance flushed plastic cannula over top of guide wire
- Uses modified Seldinger technique
- Attach syringe of Heparinized saline
- Re-flush cannula with 2 cc Heparinized saline
- Turn Stopcock to seal artery
- Connect transducer and high-pressure infusion set
- Remove pad under wrist and secure arm board
VII. Monitoring
- A-Line compatible monitors
- Continuous reading of systolic and diastolic Blood Pressure as well as mean arterial pressure
- Requires calibration and special tubing
- Disposable monitors
- Attach inline to the catheter and have a small digital screen displaying mean arterial pressure
VIII. Complications
- Arterial Thrombosis
- Risk increases with decreasing wrist circumference
- Risk increases rapidly in first 24 hours, than slowly
- Occult Hemorrhage
- Open Arterial Line can result in rapid blood loss
- Cerebral embolization
- Occurs with vigorous Flushing of radial catheters
- Gentle irrigation with 1-2 ml boluses should be used
- Localized infection
- Risk increases after 72 hours
- Remove catheter at earliest possible time
- Provide careful wound and dressing care
IX. Resources
- Arterial Line Placement - Ultrasound Guided (Dr. Mellick, Youtube)
X. References
- Killu and Sarani (2016) Fundamental Critical Care Support, p. 93-114