Indications for Arterial Line Placement
Arterial line placement should be strongly considered in patients with persistent hypotension despite treatment, hemodynamic instability requiring vasopressor therapy, or when frequent arterial blood gas sampling is needed. 1
Primary Clinical Indications
Hemodynamic Instability and Shock States
Patients with persistent low blood pressure or shock states require arterial line placement for continuous, accurate blood pressure monitoring. 1 This is particularly critical when systolic blood pressure remains low despite initial resuscitation efforts.
Arterial lines should be placed early in patients requiring vasopressor therapy to facilitate precise titration of medications like norepinephrine and to maintain target mean arterial pressure (MAP) ≥65 mmHg. 1, 2
In critically ill patients with shock, peripheral edema, or severe hypotension, invasive monitoring is essential because non-invasive blood pressure measurements become significantly inaccurate in these conditions. 3
Acute Heart Failure and Cardiogenic Shock
- In patients with acute heart failure who are refractory to pharmacological treatment or persistently hypotensive, arterial line insertion should be considered. 1 This allows for accurate assessment of hemodynamic response to therapy.
High-Risk Surgical Patients
Arterial lines should be considered at an early stage during emergency laparotomy in high-risk patients to aid physiological assessment and facilitate goal-directed hemodynamic therapy (GDHT). 1
During aneurysm surgery or neurosurgical procedures, arterial line placement before induction of anesthesia enables continuous blood pressure monitoring, though the evidence for routine placement is not definitively established. 1
Specific Clinical Scenarios Requiring Continuous Monitoring
Patients requiring frequent arterial blood gas analysis for assessment of pH, oxygenation, ventilation, electrolytes (potassium, ionized calcium), glucose, and hemoglobin should have arterial line placement. 4
In donation after circulatory death (DCD) organ procurement, an arterial line should be routinely placed prior to withdrawal of life-sustaining therapy to accurately determine loss of circulation and ensure lack of brain perfusion when normothermic regional perfusion is utilized. 1
For pelvic trauma with severe bleeding requiring resuscitative endovascular balloon occlusion of the aorta (REBOA), arterial line placement is necessary both for vascular access and to provide accurate blood pressure readings during the procedure. 1
Advanced Hemodynamic Monitoring
Arterial lines enable pulse contour analysis to assess cardiac output, stroke volume variation (SVV), and pulse pressure variation (PPV), which are critical for optimizing fluid resuscitation and guiding inotrope/vasopressor therapy in high-risk patients. 1, 4
Goal-directed hemodynamic therapy using arterial line-derived data should target a cardiac index ≥2.2 L/min/m² and MAP of 60-65 mmHg (individualized to patient comorbidities). 1
Important Technical Considerations
Site Selection
The radial artery is the preferred insertion site for most cases, though femoral artery access may be appropriate in specific situations like REBOA placement. 5, 1
In aortic dissection, the arterial line should be placed in the right radial artery, or on the left side if brachiocephalic trunk involvement is suspected. 3
Placement Technique
- Ultrasound guidance for arterial cannulation significantly reduces time to placement (107 vs 314 seconds), decreases number of attempts (1.2 vs 2.2), and requires fewer sites compared to palpation technique. 6
When Arterial Lines Are NOT Routinely Indicated
Non-invasive blood pressure monitoring suffices for most stable patients without hemodynamic instability, shock, or need for frequent blood sampling. 7
Arm cuff non-invasive mean arterial pressure readings are accurate in stable patients (mean bias 3.4 ± 5.0 mmHg), making arterial lines unnecessary in this population. 8
Quality Assurance
The fast-flush Gardner test should be performed to validate arterial catheter system accuracy, particularly in patients on vasopressors where precise blood pressure management is critical. 3 An optimally damped system shows 1-2 oscillations after the square wave before returning to baseline. 3
Proper leveling and zeroing of the transducer at the phlebostatic axis is crucial for accurate measurements. 5
Common Pitfalls to Avoid
Do not rely on non-invasive blood pressure monitoring in patients with circulatory failure, elderly patients, or those with calcified arteries, as these devices are unreliable in these populations. 4
Avoid delaying arterial line placement in patients requiring vasopressor titration, as intermittent automated oscillometry has extended intervals between measurements that are inadequate for managing critically unstable patients. 7