Catheterization and Vascular Access Review

Catheterization: Lines and Balloon Pumps

Understanding Vascular Access and Pressure Measurements

• Four basic lines provide both vascular access and pressure measurements:
  • Arterial Lines (Art-lines, A-lines):
  • Gold standard for continuous blood pressure (BP) monitoring.
  • Central Venous Catheters (CVC):
  • Essential for evaluating volume status and for medication delivery.
  • Peripheral Inserted Central Catheter (PICC Lines):
  • Allows for long-term therapy without the need for repeated venipuncture.
  • Pulmonary Artery Catheter (PAC):
  • Used for advanced hemodynamic monitoring in complex medical cases.

Arterial Lines

Definition

• Invasive arterial catheterization for direct pressure measurement.

Pressure Monitoring

• Provides beat-to-beat analysis of BP.
• Waveform Analysis:
  • Reveals cardiac function and vascular resistance.
• Blood Sampling:
  • Enables frequent arterial blood gas (ABG) analyses without repeated sticks.
• Dynamic Response:
  • Shows immediate effects of interventions.
• Calibration Requirements:
  • Zero reference at phlebostatic axis.
• Normal Values:
  • Systolic: 90-140 mmHg (average: 120 mmHg)
  • Diastolic: 60-90 mmHg (average: 80 mmHg)
  • Mean Arterial Pressure (MAP): 70-100 mmHg (average: 93.3 mmHg)

Arterial Line: Indications and Hazards

Indications

• Frequent ABG sampling.
• Continuous invasive BP monitoring.
• Hemodynamically unstable patients.
• Assessment of therapeutic interventions.
• Dye dilution QT.

Hazards

• Blood loss.
• Arterial spasm.
• Infection.
• Air embolism.
• Thrombus.
• Bleed back.

Arterial Line Placement Sites

Adults

• Radial Artery:
  • Modified Allen's test required.
  • Collateral flow via ulnar artery.
  • Preferred due to safety profile.
• Brachial Artery:
  • Larger caliber vessel with less anatomical variation and higher flow rates.
• Femoral Artery:
  • Preferred in shock states due to larger diameter; however, higher infection risk.

Children and Neonates

• Dorsalis Pedis:
  • An alternative when upper extremity access is contraindicated.
  • Lower accuracy when vasopressors are used.
• Umbilical Line:
  • Can only be obtained in neonates and is used for arterial blood sampling only.

Arterial Line Setup

Equipment Required

• Arterial catheter kit
• Pressure transducer system
• 500 mL pressure bag with normal/heparinized saline
• Ultrasound device
• Sterile barriers and PPE
• Area stabilization equipment

Procedure

1. Verify medical orders.
2. Prepare sterile equipment.
3. Don appropriate PPE and prepare a sterile field.
4. Use ultrasound or palpation to locate the artery.
5. Insert the needle catheter at a 30-45° angle.
6. Slide the sheath into the artery while removing the needle.
7. Attach the pressurized line and the transducer.
8. Stabilize and secure the catheter location.

Setup Steps

• Insert salinized bag into pressure bag and inflate to 300 mmHg.
• Priming the system and de-bubbling.
• Level transducer at phlebostatic axis.
• Adjust waveform calibration and perform dynamic response testing.
• Document the insertion site and pressure readings.

Arterial Line Waveform Components

• Duration: 0.1-0.2 seconds.
• Slope: Indicates contractility.
• Height: Reflects stroke volume.
  • Systolic Upstroke (Anacrotic Limb):
  • Represents peak systolic pressure and relates to the timing in the cardiac cycle.
  • Systolic Peak:
  • Occurs at aortic valve closure and relates to T-wave timing.
  • Analyzed using reflection wave methods.
  • Dicrotic Notch:
  • Indicates the rate of pressure decay and assesses peripheral resistance.
  • Diastolic Runoff (Dicrotic Limb):
  • Illustrates the return to baseline.
  • The dicrotic notch aligns with the T-wave peak.

Arterial Line Troubleshooting

Central Venous Catheters (CVC)

• Also known as a „Central Line.”
• Technical Specifications:
  • Lumens: Range from single to quad-lumen options.
  • Length: 15-30 cm depending on insertion site.
  • Materials: Polyurethane or silicone, with anti-microbial coating options.
  • Common sites of insertion are:
  • Internal jugular.
  • Subclavian.
  • Femoral.

Measurements

• Central Venous Pressure (CVP): Normal range: 2-6 mmHg
• Continuous central venous saturation.
• Direct pressure monitoring.
• Cardiac preload assessment.

Clinical Applications

• Vasopressor administration.
• Volume resuscitation.
• Total parenteral nutrition (TPN) delivery.
• Central venous blood sampling.
• Temporary access for hemodialysis.

CVC Placement and Setup

Insertion Sites Comparison

• Internal Jugular:
  • Success rate: 90-95%.
  • Landmark: Carotid pulse and sternocleidomastoid.
  • Advantages: Offers a straight path to the superior vena cava (SVC).
  • Complications: Risk of carotid puncture.
• Subclavian:
  • Success rate: 85-90%.
  • Landmark: Clavicle and first rib.
  • Advantages: Lower infection rates.
  • Complications: Risk of pneumothorax.

Equipment Checklist

• Ultrasound with sterile cover.
• Full barrier precautions.
• ChloraPrep/betadine.
• Local anesthetic.
• Multiple catheter sizes.
• Required post-procedure chest x-ray.

CVP Waveform Components

• Normal CVP values are 2-4 mmHg above baseline.
• a-wave (1-2 mmHg rise): Represents atrial contraction.
  • Timing correlates with P-wave.
• c-wave (2-3 mmHg drop): Indicates atrial relaxation and coincides with ventricular systole.
• x-descent (2-3 mmHg rise): Corresponds with atrial filling.
• v-wave: Represents the return to baseline during tricuspid opening with early diastolic timing.
• y-descent: Always is noted in correlation with EKG tracing.

Peripheral Inserted Central Catheter (PICC Lines)

• Lengths: 40-60 cm.
• Sizes: 3-6 French.
• Duration: Up to 12 months.
• Inserted through a peripheral vein: Terminates in the superior vena cava.

Catheter Characteristics

• Designed for long-term use, with a lower infection risk and reduced complications.
• Available in multiple lumens.

Benefits of PICC

• Uses the Modified Seldinger Technique (MST).
• Ultrasound-guided venipuncture.
• Catheter tip confirmation via methods like ECG guidance, chest radiograph, or fluoroscopy.

Advanced PICC Line Applications

Clinical Indications

• TPN.
• Poor peripheral access.
• Frequent blood sampling.
• Long-term IV therapy.
• Difficult venous access.
• Chemotherapy administration.
• Extended antibiotic therapy.

Contraindications

• Severe coagulopathy (INR > 3.0).
• Active bacteremia.
• Ipsilateral conditions:
  • AV fistulas.
  • Lymph node dissection.
  • History of radiation therapy.

Complications Management

• Includes catheter migration, thrombosis prevention, exit site infection, and mechanical phlebitis.
• Important note: Do NOT administer nitrates or nitroprusside through the CVC/PICC.

Maintenance Protocol

• Weekly dressing changes.
• Daily line assessments.
• Regular patency checks.
• Monitoring for infections.

Pulmonary Artery Catheter

Lumen Functions

• Distal Port (Yellow):
  • Used for pulmonary artery pressure monitoring and mixed venous blood sampling.
  • Continuous cardiac output measurement.
• Proximal Port (Blue):
  • Used for central venous pressure monitoring and medication administration.
  • Fluid infusion capabilities.
• Thermistor Connection:
  • Monitors temperature and calculates cardiac output with thermal dilution curves.
• Balloon Port:
  • Maximum inflation of 1.5 mL, used for wedge pressure measurements; only to be inflated intermittently.

PAC Overview

• Also known as Swan-Ganz Catheter or flow-directed balloon-tipped catheter.
• It has a 4-lumen design and measures various pressures including right atrial, pulmonary artery, left heart filling, alongside core temperature monitoring.

Pulmonary Artery Catheter: Indications and Hazards

Hazards

• Cardiac arrest.
• Arrhythmias.
• Catheter displacement.
• Risk of pulmonary infarct, air embolism, kinked catheter, balloon rupture, valve damage (on removal), infection, pneumothorax.

Indications

• Used for management of complex myocardial infarctions, post-operative heart patients, assessments of respiratory distress, shock therapy, fluid replacements, and valvular heart diseases, including cardiac tamponade.

Pulmonary Artery Catheter Placement

• Inserted through subclavian or internal jugular veins, or sometimes femoral vein (though rare).
• The catheter moves through the right atrium to the right ventricle and into the pulmonary artery, where it remains.

Pulmonary Artery Catheter: Insertion and Waveforms

• Catheter begins through the selected vein with the balloon deflated.
• Thread it until the right atrial waveform is displayed on the monitor.
• Inflate the balloon; waveform similar to a central venous catheter will be shown.
• As the catheter passes naturally with blood flow into the RV, waveform patterns change, then it will enter the PA, once again with waveform changes.
• Wait for a wedge (waveform change) once in the PA and then passively deflate the balloon.
• The balloon remains deflated; the catheter sits in the PA and continuously monitors CVP (RA) and pulmonary artery pressure (PAP).

Pulmonary Artery Catheter: Pulmonary Artery Wedge Pressure Procedure

• If unable to achieve PA wedge pressure, substitute with pulmonary artery diastolic pressure, keeping in mind that PAP diastolic will be approximately 3 mmHg higher than PA wedge pressure values.
• The balloon will inflate (no more than 1.5 mL) at end-expiration for accurate measurements, leading to the catheter “wedging” into a pulmonary artery, thus occluding blood flow.
• Observe the pressure waveform change on the monitor as this indicates the PA wedge pressure, providing insights about the left heart function.
• The balloon should be passively deflated within 15 seconds or 5 breaths.

Normal Pressures from the PAC

• CVP: 2-6 mmHg
• Right Ventricular Pressure (RV): 15-25/0-8 mmHg
• Pulmonary Artery (PA): 15-25/8-15 mmHg
• PA Wedge Pressure (PAWP): 4-12 mmHg

Hemodynamic Pressure Review

Central Venous Pressure

Causes of Decreased CVP

• Hypovolemia.
• Changes in patient or transducer position.

Causes of Increased CVP

• Increased preload and afterload.
• Hypervolemia.
• Reduced contractility.
• Tricuspid stenosis.
• Cor pulmonale.
• Right ventricular failure.
• Clot within the line.
• Patient or position changes.

Pulmonary Artery Pressure

Causes of Decreased PAP

• Pulmonary vasodilation.
• Hypovolemia.

Causes of Increased PAP

• Increased pulmonary blood flow.
• Hypervolemia.
• Pulmonary vasoconstriction.
• Pulmonary hypertension.

Pulmonary Artery Wedge Pressure

Causes of Decreased PAWP

• Hypovolemia.

Causes of Increased PAWP

• Cardiac tamponade.
• Left ventricular failure.
• Hypervolemia.
• Mitral valve regurgitation.
• Mitral valve stenosis.
• Pneumothorax.
• Mechanical ventilation.
• High PEEP effects.

Hemodynamic Pressure Interpretation

• CVP indicates right heart function.
• PAP assesses pulmonary circulation.
• PAWP evaluates left heart function.
• Systolic pressures reflect contractility.
• Diastolic pressures indicate filling.

Interpretation Summary

1. If all three values are below normal or on the low end of normal, the issue is hypovolemia.
2. If all three values are above normal or at the high end of normal, possible conditions include congestive heart failure (CHF) or hypervolemia.
3. CHF: BP, MAP, and/or cardiac output may all be below normal or on the low end.
4. Hypervolemia: BP, MAP, and/or cardiac output may all be above normal or on the high end.
5. If CVP is elevated: indicates a right heart issue and management should be adjusted accordingly.
6. If PAP is elevated: indicates a pulmonary vascular problem, necessitating further investigations or interventions.
7. If PAWP is elevated: indicates a left heart problem, further assessments are warranted.

Critical Factors Influencing Pressure Measurements

Mechanical Factors

• Transducer position influences pressure readings substantially: ±1 mmHg per inch deviation.
• Factors such as system dampening and catheter whip artifact need consideration.

Physiological Factors

• Influences can stem from respiratory variations, intrathoracic pressure changes, vasomotor tone, and cardiac rhythm fluctuations.

Equipment Considerations

• Regular calibration frequency is crucial.
• Zero reference points need to be reconfirmed.
• Perform dynamic response testing and maintain the equipment regularly.

Advanced Clinical Applications and Decision Making

Shock Management

• Cardiogenic shock: signified by PAP exceeding 25 mmHg.
• Hypovolemic shock is indicated by low filling pressures observed during monitoring.
• Distributive shock reveals low systemic vascular resistance (SVR).
• Obstructive shock presents with high right-sided pressures.

Fluid Management

• Consider both static pressure parameters and dynamic indices when assessing volume responsiveness and fluid challenges.

Medication Titration

• Important consideration for administering agents such as vasopressors, inotropes, vasodilators, and managing volume expansion.

Safety Protocols

• Maximum barrier precautions during procedures are imperative.
• Utilize ChloraPrep for skin preparation and ensure ongoing daily assessments.
• Bundle compliance, infection prevention, maintenance of pressure bag integrity, connection security, and thrombosis prophylaxis are critical.
• Focus on mechanical safety during insertion, accuracy of pressure recordings, waveform quality, and monitoring for possible complications.
• Documenting requirements must be scrupulously maintained.

Absolute and Relative Contraindications

Absolute Contraindications

• Local infection at the insertion site.
• Severe coagulopathy (platelets <50,000).
• Active bacteremia.
• Patient refusal of the procedure.

Relative Contraindications

• Moderate coagulopathy.
• Anatomical vascular variants.
• Prior vascular surgeries.
• History of local radiation therapy.

Introduction to Intra-Aortic Balloon Pumps (IABP)

• A cutting-edge mechanical circulatory support device, utilizing synchronized counter-pulsation therapy.
• Plays a critical role in modern cardiac care units and has core functions that include:
  • Reducing left ventricular workload by up to 25%.
  • Increasing coronary perfusion by 30-40%.
  • Enhancing cardiac output by 15-20%.
  • Optimizing overall systemic circulation.
• Catheter specifications:
  • Size: 7.5-8 Fr.
  • Balloon volume: 25-50 mL.
  • Length: 25-27.5 cm; insertion requires precise positioning.
  • Entry via the femoral artery (using Seldinger technique).
  • Position: Catheter tip should be 2-3 cm below the left subclavian artery, proximal tip at aortic arch, and the distal end above the renal arteries.
  • Fluoroscopic guidance is utilized during insertion for accuracy.

IABP Clinical Indications

Primary Clinical Indications

• Congestive heart failure (CHF).
• Acute myocardial infarction.
• Cardiogenic shock.
• Septic shock.
• Unstable angina.
• Pre-infarct conditions.

Secondary Clinical Indications

• Bridge to coronary artery bypass grafting (CABG).
• Bridge to heart transplantation.
• Support following CABG operations.
• Cardiac contusion cases.
• Management of mechanical cardiac defects.
• Severe mitral regurgitation.

IABP Contraindications

Absolute Contraindications

• Aortic valve insufficiency.
• Aortic dissection.
• End-stage heart disease in non-transplant candidates.
• Terminal illness considerations.
• Severe arteriosclerosis impeding catheter insertion.

Relative Contraindications

• Presence of an aortic aneurysm.
• Complications from vascular grafts.
• Aorto-femoral graft placement.
• Severe peripheral vascular disease.
• Bleeding disorders.

IABP Complications

• Risk of aortic dissection and plaque dislodgement.
• Difficulties in catheter passage leading to femoral blood flow obstruction and vascular damage.
• Insertion complications include:
  • Bleeding events.
  • Compromised leg circulation.
  • Thrombosis formation.
  • Aortic perforation risks.
  • Blood or gas embolism.
  • Issues with timing synchronization during operation.

IABP Technical Aspects

• EKG/Arterial line synchronization is crucial.
• Uses helium-based systems that provide several advantages:
  • Low viscosity facilitating swift movement.
  • Rapid movement leads to a reduced risk of ruptures.

IABP Function: Systolic Phase Mechanics

Precise Deflation Timing

• Initiated 40 ms prior to the R wave duration, lasting between 250-300 ms.
• Pressure reduction of 20-30 mmHg occurs during this phase.

Physiological Effects

• Reduces afterload by 15-20%.
• Decreases wall tension by 20%.
• Reduces myocardial oxygen demand by 25%.
• Improves ejection fraction by 10-15%.

IABP Function: Diastolic Phase Dynamics

• Triggered at the dicrotic notch, lasting 300-350 ms.
• Inflation results in pressure augmentation of 30-40 mmHg.
• Increases diastolic pressure by 30%.
• Improves coronary flow by 25-40%, optimizing subendocardial perfusion and enhancing oxygen delivery by 20%.

IABP Function: Timing Mechanics

• Heart Rate Ranges: 80-120 bpm.
• Minimum Pulsation Pressure: 20 mmHg.
• Arterial Elastance: 0.5-2.0 mmHg/mL.
• Optimal Conditions for Timing Ratios:
  • 1:1 ratio for full support.
  • 1:2 for moderate support.
  • 1:3 for weaning phase.
  • Precise systolic unloading verification and diastolic augmentation assessment is vital.
  • Balloon volume optimization strategies to be adapted based on patient requirements.

IABP Function: Performance and Monitoring

Performance Factors

• Influence from stroke volume outcomes, vascular resistance effects, aortic compliance, and balloon diameter considerations.

Monitoring Requirements

• Continuous EKG monitoring, arterial line pressure assessments, peripheral perfusion checks, coagulation status evaluations, and an overview of hemodynamic parameters are essential for patient safety and effective therapy.

Weaning Strategies

• A gradual reduction approach is advised.
• Time-off intervals: 30 minutes, 1 hour, and 2 hours should be considered based on patient responses and stability.
• Adjust balloon volumes and frequency according to the measured hemodynamic response of the patient.
• Initial Phase: Adjust ratios from 1:2 to 1:4 and finally to 1:8 based on continuous monitoring.
• Advanced Phase: focuses on monitoring patient responses alongside hemodynamic stability assessments.
• Optimize medication management and transition planning should occur alongside these strategies.

IABP Removal Criteria

• Heart Rate <110.
• Mean Arterial Pressure (MAP) >70 with minimal support required.
• Pulmonary Capillary Wedge Pressure (PCWP) <18.
• Absence of arrhythmias.
• Activated Clotting Time (ACT) <180 seconds.
• Adequate peripheral perfusion must be maintained throughout.

IABP Post-Removal Care

• A 5-hour flat position requirement should be adhered to.
• Monitor insertion site for potential pressure and possible complications such as bleeding, hematoma formation, ensure hemodynamic stability and conduct required follow-up assessments post-removal.