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.
List the normal ranges for pH, PaCO2, HCO3, and PaO2.
pH: 7.35-7.45
PaCO2: 35-45
HCO3: 22-26
PaO2: 80-100
What is the difference between hypoxemic and hypercapnic respiratory failure?
Hypoxemic respiratory failure (oxygenation failure)
• PaO2 < 60 mm Hg with either normal or slightly
subnormal PaCO2 levels
• Inadequate exchange of O2 between the alveoli and pulmonary capillaries
Hypercapnic respiratory failure (ventilator failure)
• PaCO2 > 50 mm Hg and may be accompanied by hypoxemia and/or acidemia
• Insufficient CO2 removal
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).
Determine what the pt is experiencing with the following ABGs. pH: 7.27, PaCO2: 68, HCO3: 28, PaO2: 60
pH: 7.27 low (acidic)
PaCO2: 68 high (acidic)
HCO3: 28 high (alkalotic)
PaO2: 60 low (hypoxemia)
Partially Compensated Respiratory Acidosis with hypoxemia
Ratio of air entering lungs to alveoli to the amount of blood flowing to capillaries are not equal.
What is V/Q Mismatch?
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
This flexible tube is inserted through the nose to maintain an open airway, especially useful in patients with altered levels of consciousness or during anesthesia.
What is a nasopharyngeal airway (NPA)?
NPAs are used to establish and maintain a patent airway in patients with altered levels of consciousness (ALOC). They are less likely to induce a gag reflex than other airway devices and so they may be used in conscious or semi-conscious (breathing or non-breathing) patients when the airway is at risk of compromise. However, assessment for presence of a gag reflex should still be performed.
We should not use NPAs on patients with active epistaxis, known/suspected nasal or basilar skull fractures.
The goal is to displace the tongue away from the back of the throat in order to achieve ventilation without causing trauma to the nasal cavity. Sizing is important. If it's too short, it won't displace the tongue away from the back of the throat. If it's too long, it may enter the esophagus, causing gastric distention and vomiting. It could also cause laryngospasm and subsequent vomiting. To size appropriately, measure from the tip of the nose to the tip of the earlobe. If a NPA is misplaced, hypoventilation will occur.
Name 3 causes of respiratory alkalosis. Explain each cause.
Causes: Psychogenic (fear, pain, anxiety), CNS stimulation (brain injury, ETOH,
salicylate poisoning, brain tumor), Hypermetabolic states (fever, thyrotoxicosis, sepsis, pregnancy), Hypoxia (high altitude, pneumonia,
heart failure, pulmonary embolism), Mechanical ventilator rate too fast
Name three causes of alveolar hypoventilation.
- Central Nervous system (CNS) problems
- Chest wall dysfunction
- Acute asthma
- Restrictive Lung Disease
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.
This rigid device is inserted through the mouth to prevent the tongue from obstructing the airway, commonly used in unconscious patients or during resuscitation.
What is an oropharyngeal airway (OPA)?
The OPA should displace the tongue away from the back of the throat in order to achieve ventilation without causing trauma to the oral cavity and also without obstructing the airway. Sizing the OPA is important! Measure the distance from the corner of the patient's mouth to the angle of the jaw. If it is too short, the tongue will not be displaced from the back of the throat. If it is too long, the tip of the OPA can push the tongue into the airway, completely occluding it.
An OPA can be used on both breathing and non-breathing patients, however, you MUST establish the ABSENCE of a gag reflex before placement. An OPA WILL trigger a gag reflex and induce vomiting and possible aspiration. OPAs should not be used on patients who have an active gag reflex and also should not be used on patients with known or suspected palate fractures.
Describe the difference between Assist-Control and Pressure-Control modes on the ventilator.
AC: A set respiratory rate, tidal volume, PEEP, inspiratory time, & FiO2%. Most common mode. Considered “full” support. Patient is capable of taking spontaneous breaths and set volume is delivered. Can be used for pts with or without spontaneous breaths. Reduces work of breathing and allows the respiratory muscles to rest. Risk of hyperventilation due to many spontaneous breaths at set tidal volume. May lead to respiratory alkalosis. Sedation may be needed to limit spontaneous breaths
PC: A set respiratory rate, peak inspiratory pressure (PIP), inspiratory time, & PEEP. Considered “full” support. Patient can initiate spontaneous breath and vent will deliver a volume of gas up to the set PIP limit. PIP is never exceeded, but tidal volume varies. Sedation may be needed to limit spontaneous breaths. Setting used for ARDS patients to decrease risk of volutrauma or barotrauma
Name the four primary causes of hypercapnic respiratory failure.
1. CNS problems
2. Neuromuscular problems
3. Chest wall abnormalities
4. Problems affecting airway and/or alveoli
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.
This tube is inserted through the mouth or nose into the trachea to maintain an open airway and facilitate mechanical ventilation in patients who cannot breathe on their own.
What is an endoctracheal tube (ETT)?
ETT provide access to the tracheobronchial tree which allows for easy access to secretions for suctioning. Common indications are inability to maintain own airway, ARDS, apnea, upper airway obstruction caused by trauma, tumors, burns, bleeding. Complications that can occur are trauma, accidental intubation of the pyriform sinus or the right mainstem bronchus, and cardiac arrhythmias.
Contraindications are patients with an intact gag reflex, patients likely to react with laryngospasm (such as those with epiglottitis), and naso tracheal ET in those with basilar skull fractures.
Some nursing responsibilities include: Verify proper placement. Assess for proper cuff inflation. Continuously assess tube for placement/dislodgment/cuff leak. Provide oral care and maintain integrity of oral mucosa every 2-4 hours and PRN. Implement frequent position changes and perform ROM exercises... and don't forget the VAP bundle!
This ventilator mode combines mandatory breaths with patient-triggered breaths, allowing patients to breathe spontaneously between the scheduled breaths, making it suitable for those needing partial respiratory support.
What is Synchronized Intermittent Mandatory Ventilation (SIMV) mode?
Considered partial support, unlike AC and PC mode which are both full support modes. SIMV can function like AC mode and be fully supportive if needed, however, it allows patients to use their own work of breathing when breathing spontaneously in between scheduled breaths, which is helpful when weaning patients off the vent.
Name two settings on the ventilator that is preferred for pts with ARDS.
- Low tidal volume (VT) ventilation (4-8 mL/kg) – limits volutrauma and barotrauma
- Permissive hypercapnia – consequence of low tidal volume ventilation, where PaCO2 levels will slowly rise above normal range. PaCO2 up to 60mmHg is
acceptable in ARDS
- Positive end-expiratory pressure (PEEP) – helps open collapsed alveoli
• Improves oxygenation while decreasing FiO2 needs