Hemodynamics
Common scale used to assess agitation in ICU patients
What is the Richmond Agitation-Sedation Scale (RASS)?
scored -5 to +4. -5 is no response to voice or stimulation and +4 is combative, violent and dangerous to self and others. Generally, we perform this assessment at minimum every 4 hours and as needed. We use this scale to help us titrate sedation medications to their optimal levels for the patient.
This device is used to support heart function and blood flow in individuals with weakened hearts, often serving as a bridge to heart transplantation or as a long-term solution for heart failure patients.
What is a ventricular assist device (VAD)?
VADs may also be used in patients who are postcardiotomy cardiogenic shock and those who have NY Class IV HF that has not been responsive to other treatments.
Contraindications for VAD include BSA lower than manufacturer's limit, irreversible end-stage organ damage, and life expectancy less than 3 years.
This device is inserted into the aorta and inflates and deflates in sync with the cardiac cycle to improve blood flow and reduce the workload on the heart.
What is an intra-aortic balloon pump (IABP)?
Different from the swann-ganz, which is placed in the pulmonary artery, the IABP is placed in the aorta.
IABP use is often called counterpulsation because the balloon inflates and deflates in a counter-rhythm to the heart's natural pumping cycle (deflates during systole, inflates during diastole). It is placed temporarily, reduces afterload, and improves coronary blood flow.
IABP inflation and deflation is directly related to the ECG rhythm, so it is vital that we assess to make sure the rhythm is accurate and leads are placed appropriately. The assist ratio is 1:1. As patient improves, this can be decreased to 1:2, and 1:3 just prior to removal.
Name five major modifiable risk factors for CAD. Explain how each are risk factors.
•High serum lipids: more available lipids to accumulate within vessels
•Hypertension: ↑ BP = endothelial injury = atherosclerosis = ↑ force = ↑ BP
•Tobacco use: releases catecholamines = ↑ HR, vasoconstriction, and ↑ BP = ↑ heart’s workload
•Physical Inactivity: Exercise = efficient lipid metabolism, ↑ HDL production, ↓ thrombus formation
•Obesity: BMI > 30 and waist circumference > 40 inches (men) and > 35 inches (women)
•Diabetes: causes endothelial injury and changes to lipid metabolism = ↑ cholesterol & ↑ triglycerides
•Metabolic Syndrome: cluster of risk factors for CAD (obesity, HTN, ↑ serum lipids, ↑ glucose)
Name two medications that increase contractility of the heart muscle and two different side effects for each.
Dobutamine: Hypertension, dysrhythmias, angina, headache
Digoxin: Dizziness, changes in mood and mental alertness (confusion, depression and lost interest), anxiety, nausea, diarrhea, headache, rash
Normal CVP values
2-8mmHg
CVP is also known as right atrial pressure or a measurement of right ventricular preload and it is an overall reflector of fluid volume status.
Some causes of high CVP could be: fluid volume overload, heart failure, pulmonary hypertension, or mechanical ventilation with high PEEP settings.
Some causes of low CVP could be: hypovolemia, distributive shock.
Normal PAWP values
What is 6-12mmHg.
PAWP, or pulmonary artery wedge pressure, is a measurement of pulmonary capillary pressure. It is pressure that is measured by wedging a catheter into a small branch of the pulmonary artery and inflating a balloon at the tip. This balloon does not remain inflated but rather is inflated periodically to check pressures and then deflated. It helps us to assess left ventricular (LV) function and reflects left ventricular end-diastolic pressure (LVEDP)
Low PAWP could be related to hypovolemia, septic shock, or pulmonary embolism.
High PAWP could be related to LV failure, fluid overload, pulmonary edema, mitral valve stenosis.
Severe aortic regurgitation, AORTIC DISSECTION, and uncontrolled sepsis are among the conditions that make the use of this cardiac support device inadvisable.
What is the use of an intra-aortic balloon pump?
These are all contraindications!
Some indications for IABP use are: acute MI, cardiogenic shock. short-term bridge to heart transplantation, and unstable angina that is unresponsive to drug therapy (there are lots of others, too, listed in PowerPoint and your text).
List two things about BNP.
•BNP ( B-type Natriuretic Peptide)
•A simple test that helps diagnose patients with CHF
•↑ levels by heart tissue when overloaded with pressure & excess volume
•↑ BNP is highly sensitive and specific for the diagnosis of HF
•Also useful for differentiating pulmonary and cardiac causes of dyspnea
What are the shockable rhythms?
Vfib. and V. Tach
How do you calculate mean arterial pressure (MAP)?
[(SBP)+2(DBP)]/3
Normal range 70-105mmHg (note that in practice you may see acceptable parameters lower than this range).
MAP is the average pressure which helps us understand overall blood flow and perfusion to the organs (this is very important when it comes to many ICU diagnoses, but especially in shocks).
Difference between cardiac output (CO) and cardiac index (CI)?
CO is the volume of blood that is pumped by the heart in 1 minute (SV x HR = CO). CI is the CO adjusted for body surface area; this provides for a more precise measurement for the patient and allows for very precise treatment management.
CI = CO/BSA
Inherited predisposition to develop new blood vessels.
What is angiogenesis?
Explain the difference between HFrEF and HFpEF.
Systolic/HFrEF - Inability to of the ventricles to eject properly. Will see decrease in EF (<45%). Blood backs up into left atrium & lungs, causing pulmonary edema.
Diastolic/HFpEF - Inability of the ventricles to relax & fill during diastole (usually due to stiffness & noncompliance). Results in decreased SV & CO. Diagnosis by s/s, normal EF, evidence of diastolic dysfunction on imaging
What are the normal ranges for the PR interval, QRS complex, and QT interval?
PR interval: 0.12-0.20
QRS complex: less than 0.12
QT interval: 0.34-0.43 or less than 0.50
This invasive monitoring device is indicated for assessing hemodynamic status in critically ill patients, particularly those with complex shock states, severe heart failure, or pulmonary hypertension.
What is a pulmonary artery catheter (Swann-Ganz)?
Considered the gold standard for measuring cardiac output (the swann-ganz device). Some other indications to use a PA catheter: Diagnosis or evaluation of pulmonary hypertension. Assessment of vascular resistance. Determination of etiology in cases of shock. Assessment of volume status in severe shock. Evaluation of pericardial illnesses such as cardiac tamponade or constrictive pericarditis. Assessment of right-sided valvular disease or congenital heart disease. Evaluation of intracardiac shunts.
Some contraindications could be coagulopathy, endocarditis, a right heart mass, or an endocardial pacemaker, among others.
The square wave test is commonly performed to help ensure accuracy of this invasive hemodynamic monitoring device.
What is an arterial line?
Arterial lines are used for many different types of patients. Common indications are hypotension, hypertension, respiratory failure, shocks, neuro or spinal cord injuries, coronary interventional procedures, concurrent with the use of vasoactive medications, and if ABGs are being regularly collected. A-lines are helpful in collecting continuous BP measurements (systolic, diastolic, and mean arterial pressures).
It is important to perform the square wave test at least every 8-12 hours (plus as needed) to ensure accurate waveforms which will lead to appropriate titrations and mangement of vasoactive medications.
Please reference page 782 in your book for the steps for square wave test.
Name and describe the 3 developmental stages of atherosclerosis.
Fatty Streak: lipid accumulation into smooth muscle cells, yellow tinged
Fibrous Plaque: collagen covers the fatty streak, vessel lumen narrowed, blood flow reduced, fissures develop; grey/whitish
Complicated Lesion: continued inflammation can result in plaque instability, ulceration, and rupture
Define ventricular dilation and ventricular hypertrophy.
Ventricular Dilation: Enlargement in the chambers of the heart from the muscle fibers stretching in response to increased preload à causes temporary increased contraction & subsequent increased CO for maintenance of BP & perfusion.
Ventricular Hypertrophy: Increase in the muscle mass and heart wall thickness that occurs from overwork and strain. Initially increases contractile power of the muscle fibers which increases CO & perfusion.
Name two types of pts who are appropriate for an implantable cardioverter-defibrillator.
• Have survived SCD
• Have spontaneous sustained VT
• Have syncope with inducible ventricular
tachycardia/fibrillation during EPS
• Are at high risk for future life-threatening
dysrhythmias
These potential complications of using this catheter include infection, arrhythmias, and, although rare, pulmonary artery rupture.
What is a Swann-Ganz (pulmonary catheter)?
Infection at the insertion site. Thrombosis (blood clot formation). Arrhythmias (irregular heartbeats). Pulmonary artery rupture due to balloon inflation. Air embolism (air bubble in the blood vessel). Pneumothorax (collapsed lung if the subclavian vein is used).
This type of device measures cardiac output by analyzing the arterial pressure waveform, providing continuous and real-time monitoring of a patient's heart function.
What is an arterial-based cardiac output (APCO) monitor?
APCO uses the arterial pressure waveform to estimate cardiac output. This involves analyzing the shape and characteristics of the waveform in order to calculate stroke volume (SV) and subsequently cardiac output (CO).
APCO can also assess a patient's ability to increase SV in response to fluids (fluid responsiveness) by conducting a fluid challenge test.
This is where a small amount of IV fluid is administered to the patient. If the APCO measurement shows a significant increase in stroke volume or cardiac output (usually more than 10-15%), then that indicates that the patient is 'fluid responsive' and would benefit from more IV fluids.
Name five causes of endothelial injury.
1. Hypertension
2. Tobacco use
3. Hyperlipidemia
4. Diabetes
5. Infections
6. Toxins
7. Hyperhomocysteinemia
Define preload, afterload, cardiac output, and ejection fraction.
Cardiac output=amount of blood pumped by the heart in 1 minute (norm 4-8 L/min)
Preload=amount of blood present at the end of diastole prior to the next ventricular contraction (increased by hypertension, aortic valve disease, hypervolemia)
Afterload=peripheral resistance the LV has to pump against in order to open the pulmonic/aortic valves; force opposing the movement of blood
Ejection fraction-the % of blood leaving your heart each time it contracts (norm 55-60%; measured by echocardiogram or cardiac catherization)
What are the two treatment goals for pts with A.fib?
#1 Decrease ventricular rate
• Drugs to slow HR: -adrenergic blockers, IV calcium- channel blockers
#2 Prevent embolic stroke
• Long-term anticoagulation: Coumadin, Alternative anticoagulants