Hemodynamics & Critical Care Nursing

Hemodynamics & Critical Care Nursing

Course Information

• Institution: Georgia Southern University

• Course Code: NURS 4111 – Adult Health Nursing

• Instructor: Kimberly J. Burke, MSN-Ed, RN, CCRN, SCRN

Understanding Hemodynamics

• Definition: Hemodynamics refers to blood flow, circulation, and perfusion.

• Key Concepts: Includes but is not limited to:

  • Preload

  • Afterload

  • Contractility

  • Cardiac output

  • Systemic vascular resistance

• Purpose: Nurses utilize hemodynamic monitoring to assess cardiovascular function and guide therapeutic interventions.

Preload and Afterload

Preload

• Definition: Volume of blood in the ventricles at end of diastole, also known as end-diastolic pressure.

• Conditions Leading to Increased Preload:

  • Hypervolemia

  • Regurgitation of cardiac valves

  • Heart Failure

Afterload

• Definition: The resistance the left ventricle must overcome to circulate blood.

• Conditions Leading to Increased Afterload:

  • Hypertension

  • Vasoconstriction

• Implication: Increased afterload leads to increased cardiac workload.

Cardiac Output and Its Determinants

• Formula: Cardiac Output (CO) = Stroke Volume (SV) x Heart Rate (HR)

• Stroke Volume Factors: Affected by preload, afterload, and contractility.

• Mean Arterial Pressure (MAP): Calculated using the formula:

  • MAP = rac{(2 imes Diastolic) + Systolic}{3}

• Requirement: A MAP of at least 65 mmHg is required for adequate organ perfusion.

Invasive Hemodynamic Monitoring

• Arterial Lines:

  • Provide continuous blood pressure monitoring.

  • Allow arterial blood gas sampling.

• Pulmonary Artery Catheters (Swan-Ganz):

  • Measure pulmonary artery pressures, cardiac output, and preload.

• Central Venous Catheters (CVC):

  • Measure Central Venous Pressure (CVP), which assesses fluid volume status and right heart function.

Arterial Line Nursing Safety & Care Considerations

• Ensure proper securement to prevent accidental dislodgement.

• Maintain continuous pressure monitoring to detect fluctuations in blood pressure.

• Utilize aseptic technique to handle the line, reducing infection risk.

• Regularly assess distal circulation and capillary refill to monitor for compromised perfusion.

• Calibrate and zero the transducer at the phlebostatic axis for accurate readings.

• Keep the arterial line patent by delivering a small amount of fluid under pressure.

The Pulmonary Artery Catheter

Insertion Protocol

• Prime the catheter before insertion.

• Ensure the catheter is free of air.

• System must be properly zeroed prior to insertion.

• Monitor patients for dysrhythmias during placement.

• Observe appropriate waveforms as catheter passes through correct chambers.

• Infection prevention is critical.

• Monitor for complications such as spontaneous wedging, pulmonary infarction, and pulmonary artery rupture.

Normal Readings

• Heart Failure Indicators: Increased readings.

• Hypovolemia Indicators: Changes in usual readings.

Swan-Ganz Monitoring Parameters

• Right Atrial Pressure (RAP): 0 - 6 mm Hg

• Right Ventricular Pressure (RVP): 15 - 25 mm Hg

• Pulmonary Artery Pressure (PAP): 15 - 25 mm Hg

• Pulmonary Capillary Wedge Pressure (PCWP): 8 - 12 mm Hg

• Mean PAP: 10 - 20 mm Hg

Central Venous Pressure (CVP)

• Definition: Pressure within the Superior Vena Cava/Right Atrium.

• Normal Values: 3-8 mmHg.

• Transducer Zeroing: At the mid-axillary line, 4th intercostal space (Right Atrium).

• Patient Positioning: Supine with head of the bed elevated to 45 degrees.

• Patient Criteria: Must be relaxed with normal respiratory rate and heart rate, no arrhythmias.

• Documentation: If on ventilator, read at end-expiration.

• Patency Maintenance: Use a small volume of fluid delivered under pressure.

Non-Invasive Hemodynamic Monitoring

• Echocardiography: Assesses cardiac function, preload, and contractility.

• Doppler Ultrasound: Evaluates blood flow velocity and cardiac output.

• Non-Invasive BP Monitoring: Provides indirect yet valuable hemodynamic data.

Shock and Hemodynamic Profiles

• Definition of Shock: Inability of the circulatory system to deliver adequate oxygen and nutrients to tissues.

Types of Shock:

1. Hypovolemic Shock:

   • Characteristics: Decreased preload, low cardiac output, high systemic vascular resistance.

2. Cardiogenic Shock:

   • Characteristics: Low cardiac output, high preload, high systemic vascular resistance.

3. Distributive Shock (Septic, Anaphylactic, Neurogenic):

   • Characteristics: Low systemic vascular resistance, variable cardiac output.

Hypovolemic Shock

• Causes: Hemorrhage, dehydration, burns, or third-spacing.

• Signs: Tachycardia, hypotension, low CVP, cold clammy skin.

• Nursing Interventions: Focus on rapid fluid resuscitation with crystalloids and blood products.

Cardiogenic Shock

• Causes: Myocardial infarction, heart failure, severe arrhythmias.

• Signs: Hypotension, pulmonary edema, jugular vein distention, weak peripheral pulses.

• Management: Inotropic support (e.g., dobutamine), diuretics, vasodilators, possible mechanical circulatory support.

Septic Shock

• Causes: Systemic infection and inflammation lead to profound vasodilation.

• Early Signs: Warm skin, tachycardia, low blood pressure.

• Late Signs: Cold extremities, multi-organ dysfunction.

• Treatment: Aggressive fluid resuscitation, vasopressors, early antibiotic therapy.

Neurogenic Shock

• Definition: Occurs after spinal cord injury, resulting in hypotension and bradycardia.

• Management: Includes vasopressors, epinephrine, fluid resuscitation, and airway support.

Anaphylactic Shock

• Causes: Severe allergic reaction leading to airway edema and hypotension.

• Management: Similar to neurogenic shock, focusing on emergency airway support and rapid fluid resuscitation.

Pharmacologic Management of Hemodynamics

• Vasopressors:

  • Examples: Norepinephrine, dopamine, phenylephrine.

  • Function: Increase blood pressure by causing vasoconstriction.

• **Inotropes: **

  • Examples: Dobutamine, milrinone.

  • Function: Enhance myocardial contractility.

• Vasodilators:

  • Examples: Nitroglycerin, nitroprusside.

  • Function: Reduce preload and afterload.

Nursing Considerations for Hemodynamic Medications

• Administration: Titrate vasopressors carefully based on blood pressure and perfusion status.

• Route: Administer vasopressors via central line to prevent tissue extravasation.

• Monitoring: Watch for signs of excessive vasoconstriction, including cool extremities and poor capillary refill.

Diseases Affecting Hemodynamics

• Heart Failure: Leads to elevated central venous pressure and low cardiac output.

• Pulmonary Hypertension: Results in high pulmonary artery pressures and right heart strain.

• Sepsis: Causes widespread vasodilation, fluid shifts, and heightened risk of multi-organ failure.

Nursing Management of Hemodynamic Instability

• Monitor vital signs and perfusion status.

• Closely monitor urine output.

• Strive to optimize oxygen delivery and ensure adequate fluid resuscitation.

• Adjust medication therapy based on hemodynamic responses and laboratory values.

Hemodynamics and Mechanical Ventilation

• PEEP Impact: Positive end-expiratory pressure can reduce cardiac output through increased intrathoracic pressure.

• High Tidal Volumes: May decrease venous return and cause hypotension.

• Nursing Role: Monitor hemodynamic stability and adjust fluid therapy as needed.

Nursing Prioritization in Hemodynamics

• Assess for signs of inadequate perfusion such as altered mental status, hypotension, and weak pulses.

• Early initiation of fluid resuscitation in shock states.

• Titrate vasopressors based on the patient’s needs.

• Ensure proper oxygenation and assist with mechanical ventilation support for critically ill patients.

NCLEX Style Questions

1. Question: A nurse is caring for a critically ill patient with a newly placed pulmonary artery (Swan-Ganz) catheter. Which finding requires the nurse to take immediate action?

   • A. Pulmonary artery wedge pressure (PAWP) of 10 mmHg

   • B. Central venous pressure (CVP) of 6 mmHg

   • C. Sudden flattening of the pulmonary artery waveform

   • D. Mean arterial pressure (MAP) of 75 mmHg

2. Question: A nurse is monitoring a patient with an arterial line. Which action should the nurse take to ensure accurate blood pressure readings?

   • A. Position the transducer at the level of the phlebostatic axis

   • B. Inflate the pressure bag to 200 mmHg

   • C. Flush the arterial line every 2 hours with heparinized saline

   • D. Zero the transducer once every 24 hours

3. Question: A nurse is caring for a patient with cardiogenic shock receiving continuous norepinephrine via central venous catheter. The nurse notes the following hemodynamic values: Mean arterial pressure (MAP): 55 mmHg, Central venous pressure (CVP): 2 mmHg, Cardiac output (CO): 3.5 L/min. Which priority intervention should the nurse anticipate?

   • A. Increase the norepinephrine infusion rate

   • B. Administer a 500 mL normal saline bolus

   • C. Prepare for emergency intubation

   • D. Titrate nitroglycerin infusion for afterload reduction

Key Takeaways and Summary

• Understanding hemodynamics is crucial for assessing circulatory stability and ensuring effective organ perfusion.

• Early intervention during shock states is vital for improving patient outcomes.

• Nurses must adeptly recognize hemodynamic changes and implement timely, appropriate interventions to maintain patient stability.