Cardiovascular Monitoring in ICU Notes

Cardiovascular Monitoring in ICU

Introduction

• Cardiovascular monitoring is vital in critical care due to the dependence of patient survival on competent cardiac performance.

• Hemodynamic monitoring offers clinical data on blood pressure, fluid volume, and cardiac status via invasive catheters.

• Respiratory Therapists (RTs) must understand catheter placement, data interpretation, catheter usage, and potential complications.

Learning Objectives

• Review heart anatomy and physiology.

• Review normal blood flow through the heart.

• Describe arterial cannulation, central venous pressure (CVP) monitoring, and pulmonary artery pressure monitoring.

• Enumerate indications for catheter placement.

• Identify common catheter insertion sites.

• Describe catheter placement procedures.

• Interpret arterial pressure measurements and their significance.

• Identify potential complications of catheter insertion.

Cardiovascular System Components

• Heart

• Blood vessels

  • Arteries: Carry oxygenated blood away from the heart.

  • Veins: Carry deoxygenated blood towards the heart.

  • Capillaries: Facilitate fluid exchange between blood and interstitial space.

The Heart

• Located in the Mediastinum.

Heart Layers

• Pericardium:

  • Double-walled membranous sac.

• Pericardial space:

  • Space between parietal and visceral layers.

  • Contains pericardial fluid.

Chambers of the Heart

• Atria:

  • Receive blood from veins.

  • Send blood to ventricles.

  • Separated by the interatrial septum.

• Ventricles:

  • Receive blood from the atria.

  • Send blood to arteries.

  • Separated by the interventricular septum.

Valves of the Heart

• Atrioventricular valves (AVs):

  • One-way flow from atria to ventricles.

    • Right: Tricuspid valve.

    • Left: Bicuspid (mitral) valve.

• Semilunar valves:

  • One-way flow from ventricles to pulmonary artery or aorta.

    • Pulmonic semilunar valve.

    • Aortic semilunar valve.

Blood Flow Through the Heart

• Superior vena cava → Right atrium → Tricuspid valve → Right ventricle → Pulmonic valve → Pulmonary artery → Lungs → Pulmonary veins → Left atrium → Mitral valve → Left ventricle → Aortic valve → Aorta → Body.

Hemodynamic Parameters

• Preload: Amount of blood returning to the right side of the heart.

• Afterload: Pressure against which the left ventricle pumps to eject blood.

• Compliance: How easily the heart muscle expands when filled with blood.

• Contractility: Strength of the heart muscle contraction.

• Stroke volume

Cardiac Output

• Crucial for tissue perfusion, end-organ function, and delivering oxygen and nutrients to body cells.

• Poor cardiac output leads to:

  • Decreased LOC (brain).

  • Chest pain, weak peripheral pulses (heart).

  • SOB, crackles, rales (lungs).

  • Cool, clammy, mottled extremities (tissues).

Causes of Decreased and Increased Cardiac Output

• Decreased CO:

  • Bradycardia.

  • Arrhythmias (Pulseless V-tach, V-fib, Asystole).

  • Hypotension.

  • MI.

  • Cardiac muscle disease.

• Increased CO:

  • Increased blood volume (sometimes).

  • Tachycardia (sometimes).

  • Medications (Inotropes).

Blood Pressure

• Systemic arterial blood pressure (BP) is the force exerted against artery walls when blood is pumped.

• Expressed as systolic pressure over diastolic pressure.

• Systolic pressure:

  • Highest pressure attained in the artery.

  • Determined by:

    1. Stroke volume of left ventricle.

    2. Rate of blood ejection from left ventricle.

    3. Elasticity of the arterial tree.

• Diastolic pressure:

  • Lowest pressure attained in the artery.

  • Determined by:

    1. Magnitude of preceding systolic pressure.

    2. Length of ventricular diastolic interval.

Blood Pressure Assessment

• Systolic pressure assesses left ventricular function.

• Diastolic pressure assesses peripheral resistance.

• Stroke volume is significant for systolic pressure.

• Peripheral resistance is significant for diastolic pressure.

• The difference between systolic and diastolic pressures is the pulse pressure.

Mean Arterial Pressure (MAP)

• Represents the average pressure over one complete cardiac cycle.

• Measured directly via an arterial line or estimated by formula.

• $MAP = [Systolic + (2 * Diastolic)]/3$

• Indicator of left ventricular afterload.

• Reflects an inverse relationship with stroke volume.

• Represents a direct relationship with myocardial oxygen consumption and myocardial work.

Arterial Blood Pressure Measurement

• Measured with a sphygmomanometer cuff inflated above the patient’s BP.

• The first sound heard (Korotkoff sounds) when deflating the cuff represents systolic pressure.

Reference Ranges for Hemodynamic Pressures

• Arterial pressure (BP): Systolic 100-140 mm Hg, Diastolic 60-90 mm Hg, typically 120/80 mm Hg (90/60 in teenage girls).

• Mean Arterial Pressure (MAP): 70-105 mm Hg.

• Central Venous Pressure (CVP): 2-6 mm Hg (mean).

• Right Atrial Pressure (RAP): 2-6 mm Hg (mean).

• Right Ventricular Pressure (RVP): Systolic 15-30 mm Hg, Diastolic 2-8 mm Hg.

• Right Ventricular End-Diastolic Pressure (RVEDP): 2-6 mm Hg.

• Pulmonary Artery Pressure (PAP): Systolic 15-30 mm Hg, Diastolic 8-15 mm Hg.

• Mean Pulmonary Artery Pressure (MPAP): 9-18 mm Hg.

• Pulmonary Artery Wedge Pressure (PAWP): 6-12 mm Hg.

• Left Atrial Pressure (LAP): 4-12 mm Hg.

• Left Ventricular Pressure (LVP): Systolic 100-140 mm Hg, Diastolic 0-5 mm Hg.

• Left Ventricular End-Diastolic Pressure (LVEDP): 5-12 mm Hg.

Hemodynamic Changes in Common Clinical Conditions

• ↑ = Increased

• ↓ = Decreased

• N = Normal

Arterial Pressure Monitoring

• Crucial for assessing cardiovascular tone and oxygen delivery.

• Involves direct measurement via arterial cannula insertion.

• Cannula connects to a sterile, fluid-filled system linked to an electronic patient monitor for continuous BP monitoring.

Indications for Arterial Pressure Monitoring

• Continuous blood pressure monitoring.

• Hemodynamic monitoring (surrogate measures of hemodynamic status).

• Arterial blood sampling for serial blood gases or other tests.

Contraindications for Arterial Pressure Monitoring

• Vascular compromise at or distal to the desired site.

• Vascular abnormality at the desired site.

• Infection in overlying tissues.

• Coagulopathy (INR ≥ 3, aPTT ≥ 100 sec, Platelets <50 x $10^9$/L).

• Recent thrombolytic administration.

• Therapeutic anticoagulation.

Arterial Catheter Insertion Sites

• Radial (preferred).

• Ulnar.

• Brachial.

• Axillary.

• Femoral.

Insertion Site Details

Advantages and Disadvantages of IBP Measurement

• Advantages:

  • Continuous blood pressure recording.

  • Accurate BP even in profound hypotension.

  • Real-time visual display.

• Disadvantages:

  • Potential complications.

  • Skilled technique required.

  • Expensive.

Equipment Set-Up for Arterial Cannulation

• Arterial cannula (Polytetrafluoroethylene).

  • 20G (pink) - adult patients.

  • 22G (blue) - pediatrics.

  • 24G (yellow) - neonates and small babies.

• Arterial giving set.

• Angiocatheter-style setup.

Materials Needed for Arterial Cannulation

• Antiseptic site prep.

• Sterile gloves.

• Sterile towels or drape.

• Positioning aids.

• Arterial line insertion kit.

• 1% lidocaine without epinephrine.

• Transducer, arterial line non-compliant tube set, 500mL sterile saline with pressure bag.

• Ultrasound (linear probe) with sterile probe cover.

• Non-absorbable suture and transparent dressing.

Arterial Line Insertion Procedure

1. Identify arterial pulse by palpation.

2. Perform Allen test.

3. Sterile technique.

4. Local anesthesia with lidocaine.

5. Insert arterial catheter under ultrasound guidance or palpation at a 30-45º angle.

   • Direct puncture.

   • Separate guidewire.

   • Integral guidewire.

6. Hold pressure after needle/guidewire removal.

7. Secure catheter with suture or sutureless fixation device.

8. Use a continuous flush system with normal saline solution containing heparin.

9. Assess daily for inflammation or ischemia.

10. Limit cannulation to 4 to 5 days at one site.

Radial Artery Catheterization Techniques

• Figures provided comparing Separate-Guidewire Technique and Integral-Guidewire Technique, detailing needle, guidewire, and catheter advancement.

Arterial Line Placement Procedure

1. Allen’s Test to ensure adequate collateral circulation.

2. Clean the site with Chloraprep solution.

3. Anesthetize the site with 1% lidocaine.

4. Incise the skin with a scalpel.

5. Insert the arterial needle into the skin and radial artery at a 30 to 60-degree angle until pulsatile blood flows into the column.

6. Advance the guide-wire through the arterial needle; it will curve into the radial artery.

7. Advance plastic catheter over guide-wire, remove the guide-wire, and connect to pressure tubing.

8. Anesthetize skin and suture catheter in place; place Tegaderm over the skin and secured line.

Pressures Measured on the Arterial Waveform

1. Systolic pressure (peak of the waveform, normally ~120 mm Hg).

2. Diastolic pressure (lowest point of the waveform, normally 60 to 80 mm Hg).

3. Pulse pressure (difference between systolic and diastolic pressures, normally ~40 mm Hg).

4. Mean arterial pressure (MAP) representing average pressure during the cardiac cycle (normally 80 to 100 mm Hg).

MAP Calculation

• $MAP = [Systolic + (2 * Diastolic)]/3$

Dicrotic Notch

• Represents aortic valve closing.

• If not visible, pressure readings may be inaccurate.

• May disappear when systolic pressure drops below 50 to 60 mm Hg.

The Square Wave Test

• Figures illustrating Optimally Damped, Overdamped, and Underdamped waveforms.

Complications with Arterial Lines

1. Arterial vasospasm.

2. Thrombosis.

Troubleshooting for Arterial Lines

1. "Damped" pressure tracing:

   • Occlusion by clot: aspirate and flush with heparinized saline.

   • Catheter tip against vessel wall: reposition catheter.

   • Clot in transducer or stopcock: flush system or change stopcock.

   • Air bubbles: disconnect transducer and flush.

2. Abnormally high or low pressure readings:

   • Improper calibration: recalibrate.

   • Improper transducer position: level with patient’s heart.

3. No pressure reading:

   • Improper scale selection: select appropriate scale.

   • Transducer not open to catheter: check connection.

Monitoring of Central Venous Pressure (CVP) – Right Atrial Pressure

• CVP is the pressure in the right atrium or vena cava.

• Represents right ventricular end-diastolic pressure (RVEDP) and right ventricular preload.

• Measured via venous catheter in a major vein.

• Normal range: 2 to 6 mm Hg.

• CVP is a measure of right atrial preload.

Indications for CVP Monitoring

1. Assess circulating blood volume.

2. Guide fluid replacement therapy.

3. Patients with pulmonary edema.

4. Evaluate right ventricular damage due to myocardial infarction.

CVP Catheters and Insertion Sites

• Catheters:

  • Single-lumen.

  • Triple-lumen.

• Insertion Sites:

  • Subclavian veins.

  • Internal jugular veins.

CVP Catheter Insertion Site Comparison

Procedure for Inserting a CVP Catheter

• Equipment Needed:

  • Venous pressure tray.

  • Cutdown tray or percutaneous catheter insertion tray with introducers.

  • Infusion solution/infusion set with CVP manometer or semi-rigid pressure tube.

  • IV pole, arm board.

  • Sterile dressing and tape.

  • Gowns, masks, caps, and sterile gloves.

  • Heparin flush system and pressure bag.

  • ECG monitor.

• Procedure Preparatory Phase:

  1. Assemble equipment.

  2. Explain procedure, obtain consent, explain Valsalva maneuver.

  3. Position patient supine (Trendelenburg for jugular veins).

  4. Flush IV infusion set and manometer or prepare heparin flush.

  5. Institute electrocardiogram.

• Phlebostatic axis at the intersection of the fourth intercostal space (ICS) and midaxillary line corresponds with the location of the right atrium

• Insertion phase

  1. Clean insertion with surgical prep

  2. Advance catheter percutaneously or via cutdown.

  3. Monitor and assist patient keeping them motionless during insertion.

  4. Monitor for dysrhythmias, tachypnea, and tachycardia

  5. Connect prepared IV tubing/heparin

Measuring CVP

• Manometer system (intermittent readings, less accurate).

• Transducer system (continuous readings on a monitor).

Procedure for Determining CVP with a Manometer

• Figures illustrating manometer setup, zero point adjustment, and catheter placement.

CVP Waveforms and Their Significance

• a wave (atrial contraction).

• c wave (tricuspid valve closure).

• v wave (atrial filling).

Interpretation of CVP Measurements

• Decreased CVP usually indicates hypovolemia.

  • Vasodilation (drugs, hyperpyrexia, sepsis).

  • Inadequate circulating blood volume.

  • Spontaneous inspiration.

  • Transducer above the patient’s right atrium.

• Increased CVP may suggest:

  • Fluid overload.

  • Valve issues.tricuspid/pulmonic

  • Right ventricular failure.

  • Cardiac tamponade.

  • Septal defect

  • Pulmonary embolism.

Complications of CVP Monitoring

• Bleeding or pneumothorax during placement.

• Infection (most common over time).

Pulmonary Artery Pressure Monitoring

• PAP is the systolic and diastolic pressure in the pulmonary artery.

• Measured via pulmonary artery catheter (PAC).

• Important in critically ill patients (sepsis, ARDS, pulmonary edema, MI).

• Also referred to using a flow-directed Pulmonary Artery Catheter.

• PAC provides a better assessment of left-sided heart function.

PAC Measurements include:

• Left ventricular preload (PAWP).

• Cardiac output (stroke volume and cardiac index).

• Pulmonary vascular resistance (PVR).

• Mixed venous $O_2$ content.

• Proportion of left-to-right shunted pulmonary blood flow.

• Patient’s response to therapy.

Indications for Pulmonary Artery Pressure Monitoring

• Severe cardiogenic pulmonary edema.

• Severe ARDS.

• Major thoracic surgery.

• Cardiogenic or septic shock.

Pulmonary Artery Catheters and Insertion Sites

• PACs (Swan-Ganz catheters) are radiopaque polyvinylchloride.

• Adult version ~110 cm long, marked in 10-cm increments with an inflatable balloon.

• Large children & Adult: 7-8 FR size, Small children up to 20kg : 5 FR size.

Parts of PAC

1. Distal channel (PAP measurement).

2. Proximal channel (CVP or right atrial pressure).

3. Balloon inflation channel (PCWP measurement).

4. Extra port for continuous infusion.

5. Computer connector (CO computer, pacemakers, mixed venous $O_2$ sensor).

Insertion of the Pulmonary Artery Catheter

1. Common insertion sites: Basilic, internal jugular, subclavian, or femoral vein.

2. Continuous monitoring of catheter pressure, waveform, and ECG.

3. Catheter advanced into the right atrium, balloon inflated, and catheter flows through the right atrium, right ventricle, and into the pulmonary artery, where it “wedges” into a distal branch.

4. Pressures and waveforms recorded as catheter passes through the right side of the heart.

Pulmonary Artery Pressure Measurement

• Equipment setup and calibration.

• Patent distal lumen.

• Deflated catheter balloon.

• Record PAP data.

Interpretation of Measurements

Elevated PAP values usually seen with the following conditions:

• a. Left ventricular failure/congestive heart failure, acute myocardial infarction, or fluid overload.

• b. Pulmonary hypertension from COPD

• c. Pulmonary hypertension from a pulmonary embolism

Decreased pulmonary artery pressure values are not frequently seen

• a. Patients with hypovolemic shock, anaphylaxis (allergic shock), or excessive use of vasodilating drugs may have a decreased pulmonary artery pressure.

• b. The most obvious clinical sign in these patients is a low systemic blood pressure.

Pulmonary Capillary Wedge Pressure = (PCWP)

• refers to the pressure measured in the pulmonary capillary bed under no-flow conditions.

• When the balloon at the distal end of the catheter is inflated, it wedges in a branch of the pulmonary artery blocking blood flow from the right side of the heart.

• The transducer measures the back pressure through the pulmonary circulation, which is equal to pressure in the left atrium and to the left ventricular end-diastolic pressure (LVEDP).

• PCWP, therefore, is a measurement of pressure in the left side of the heart.

• As stated, the balloon should not be inflated any longer than

The normal PCWP value is 5 to 10 mm Hg. A PCWP value of more than 18 mm Hg usually indicates impending pulmonary edema.

Conditions that Increase PCWP

• Left ventricular failure

• Mitral valve stenosis

• Aortic valve stenosis

• Systemic hypertension

Conditions that decrease PCWP

• Hypovolemia

• Pulmonary embolism (PCWP may be normal or decreased)

Complications of Pulmonary Artery Catheter Insertion

1. Damage to tricuspid valve.

2. Damage to pulmonary valve.

3. Pulmonary infarction.

4. Pneumothorax.

5. Cardiac arrhythmias.

6. Air embolism.

7. Ruptured pulmonary artery.

Central Line Bundle

• Evidence-based interventions to improve patient outcomes in the ICU.

• Focused on reducing catheter-related bloodstream infections.

• Requires collaboration within the critical care team.

• The five key components in a bundle

  1. Hand hygiene

  2. Maximal barrier precautions

  3. Chlorhexidine skin antisepsis

  4. Optimal catheter site selection

  5. Daily review of line status

Hand Hygiene

• Hand hygiene involves washing hands or using an alcohol-based waterless hand cleaner.

• When caring for central lines, appropriate times for hand hygiene include:

  • Before and after palpating catheter insertion sites

  • Before and after inserting, replacing, accessing, repairing, or dressing an intravascular catheter
    When hands are obviously soiled or if contamination is

• suspected:

  • Before and after invasive procedures

  • Between patients

  • Before donning and after removing gloves

  • After using the bathroom

Maximal Barrier Precautions

• Strict compliance with hand hygiene (above)

• Wear a cap, mask, sterile gown, and sterile gloves; consider protective eyewear for arterial line insertion

• Cover the insertion area with a sterile fenestrated drape

• Use a sterile sleeve to protect pulmonary artery catheters during insertion

• Wear either clean or sterile gloves when changing the dressing on intravascular catheters

• Use either sterile gauze or sterile, transparent, semipermeable dressing to cover the catheter site

• Replace catheter site dressing if the dressing becomes damp, loosened, or visibly soiled

• Avoid using topical antibiotic ointment or creams on insertion sites (can promote fungal infections)

• Replace gauze dressings every 2 days and transparent dressings at least every 7 days

• Scrub access port and diaphragm with antiseptic (e.g., chlorhexidine, povidone iodine, 70% alcohol) and access only with sterile devices

Chlorhexidine Skin Antisepsis

The technique, for most kits, is as follows:

• Prepare skin with antiseptic-detergent chlorhexidine 2% in 70% isopropyl alcohol

• Pinch wings on the chlorhexidine applicator to break open the ampule (when ampule is included)

• Hold the applicator down to allow the solution to saturate the pad

• Press sponge against skin, using a back-and-forth friction scrub for at least 30 seconds

• Let solution dry completely before puncturing the site (about 2 minutes)

• If chlorhexidine is contraindicated, use tincture of iodine, an iodophor, or 70% alcohol Note: Palpation of the insertion site should not be performed after antiseptic application.

Optimal Catheter Site Selection

• Whenever possible, avoid the femoral site in adults

• For central venous pressure and pulmonary artery catheters, prioritize the subclavian site over the jugular

• Avoid brachial site for arterial lines in children

Daily Review of Central Line Status

• Remove the arterial catheter as soon as it is no longer needed

• Evaluate the catheter insertion site daily by palpation and inspection

• Monitor the catheter sites visually when changing the dressing If the patient has local tenderness or other signs of infection, remove dressing and visually inspect the site

• Do not routinely replace catheters to prevent catheter-related infections; replace only when there is a specific indication

• Encourage patients to report any changes in their catheter site or any new discomfort to their provider

• Replace tubing assembly, continuous flow device, and transducers every 96 hours