Monitoring and Diagnostics (CMC) Flashcards
The cardiovascular system is regulated by two types of mechanisms:
(broad)
neural and hormonal mechanisms
neural: the autonomic nervous system modulates heart rate and vascular tone through SNS and PNS pathways.
hormonal: like adrenaline, influence CO and vascular resistance
cardiac output
SVxHR
the volume of blood pumped by the heart per minute
normal:
CVP
reflects right atrial pressure and is indicative of venous return and fluid status (? may be old news)
normal:
Pulmonary Artery Pressure (PAP)
provides information about the pressure in the PA and can indicate left heart function
normal:
Pulmonary Capillary Wedge Pressure (PCWP)
estimates left atrial pressure, aiding in diagnosing LV dysfunction
normal:
Systemic vascular resistance (SVR)
reflects resistance faced by blood flow through systemic circulation, impacting afterload
normal:
stroke volume (SV)
amount of blood ejected with each heartbeat
normal:
how does echocardiography work?
a transducer emits high-frequency sound waves that penetrate the chest wall and reflect off cardiac structures. The reflected waves are captured and translated into visual images by a computer, to observe heart chambers, valves, walls, and surrounding structures.
What does echo allow for the assessment of?
ventricular size and function, ejection fraction, and wall motion abnormalities
valve morphology (measuring blood flow velocities across valves, aiding in determining severity of valvular lesions)
stress echocardiography
combines exercise or pharmacological stress with US imaging to evaluate myocardial perfusion and ischemia. helps identify CAD by revealing areas of reduced blood flow under stress conditions.
echo can help diagnose
heart failure, cardiomyopathy, ischemic heart disease, valvular heart disease
three-dimensional echocardiography
advanced technique that offers volumetric imaging, enhancing the spatial understanding of complex cardiac anatomy. useful in pre-surgical planning and assessing congenital heart defects.
PR interval indicates
time taken for electrical conduction from atria to ventricles
QRS duration assesses
ventricular depolarization time
prolonged indicates BBB or ventricular hypertrophy
QT interval measures
total time for ventricular depolarization and repolarization
prolonged: increase risk for torsades de pointes
What do Troponin I and T measure?
myocardial injury/ infarction
used to diagnose ACS
What do B-type Natriuretic Peptide (BNP) and N-terminal pro B-type Natriuretic Peptide (NT-proBNP) measure?
heart failure
elevated levels correlate with increased cardiac stress and fluid overload.
helps differentiate between cardiac and non-cardiac causes of dyspnea
What is the purpose of a stress test?
evaluate CV systems response to increased physical activity or pharmacologic stimulation to assess how well the heart handles work and to identify potential CAD, arrhythmias, and other cardiac conditions.
primary goal is to detect ischemia (ST segment depression)
exercise stress test vs. pharmacologic stress test vs. nuclear stress test
exercise: most common. physical exertion.
pharm: used if cannot exercise. using agents like adenosine, dipyridamole, or dobutamine to mimic exercise by increasing workload of heart
nuclear: injection of radioactive tracer to highlight blood flow patterns in heart muscle during rest and stress conditions
stress echocardiography:
uses US waves to visualize heart structures and function during stress
why do stress echo or nuclear stress test instead of just exercise or pharm stress test?
used with stress testing for enhanced diagnostic accuracy
what is remote cardiovascular monitoring? benefits?
wearable or implantable device that transmits data to healthcare providers via secure networks. (smartwatches, patches, implantable loop recorders, Holter monitors, event monitors, etc)
-continuous monitoring outside of hospital/clinic. early detection of potential issues, real time data vs periodic assessments
What is a pulmonary artery sensor?
used in remote CV monitoring to assess hemodynamic parameters directly within pulmonary artery to detect changes in cardiac function via wireless sensor
name the structures of the upper airway and their function
nose, nasal cavity, pharynx, and larynx
filter, warm, humidify incoming air
name the structures of the lower airway
trachea, bronchi, bronchioles, and alveoli
explain gas exchange in the alveoli
diffusion oxygen from inhaled air diffuses across the alveolar membrane into the pulmonary capillaries, while CO2 from deoxygenated blood diffuses into the alveoli to be exhaled. this exchange is driven by concentration gradients and facilitated by a thin respiratory membrane and a large surface area provided by numerous alveoli
why is oxygenation/ventilation so important in cardiac patients?
effective ventilation ensures adequate oxygenation of blood returning t the left side of the heart for systemic circulation. inadequate ventilation or impaired gas exchange can lead to hypoxemia and hypercapnia, which can affect cardiac output and exacerbate cardiac conditions
also if they’re anemic: less hgb circulating to carry oxygen to tissues
ABGs are used to monitor ______ via the levels of _______
oxygenation, ventilation, and acid-base status via the levels of oxygen (PaO2), carbon dioxide (PaCO2), and the pH of arterial blood
the primary components measured in an ABG test include
pH, partial pressure of oxygen (PaO2), partial pressure of carbon dioxide (PaCO2), bicarbonate (HCO3), and oxygen saturation (SaO2)
pH indicates
acidity or alkalinity of the blood
partial pressure oxygen (PaO2) measures
oxygen levels in the blood with normal values ranging from 75 to 100 mmHg
helps assess how well oxygen is being transferred from the lungs to the blood
partial pressure carbon dioxide (PaCO2) measure
effectiveness of ventilation by measuring CO2 levels, with normal between 35 to 45 mmHg.
elevated suggests hypoventilation or respiratory acidosis
low levels- hyperventilation or respiratory alkalosis
bicarbonate (HCO3) measures
metabolic component and buffering capacity, with normal between 22 and 26 mmHg
distinguish between metabolic acidosis and alkalosis
oxygen saturation (SaO2) measures
a more precise measurement of hemoglobin saturation with oxygen compared to the pulse oximetry (SpO2)
mixed venous gas is a measurement of
gases in blood collected from the pulmonary artery, reflecting overall balance between oxygen delivery and consumption throughout the body.
assesses adequacy of tissue oxygenation and determining effectiveness of CO
primary components of mixed venous gas
partial pressures of oxygen (PvO2) and carbon dioxide (PvCO2) as well as venous oxygen saturation (SvO2).
Normal SvO2 values and abnormal indications
normal 60-80%
below: suggest increased oxygen saturation due to inadequate delivery or heightened demand.
above: decreased extraction or impaired utilization
What does SvO2 assess?
how much oxygen remains in the blood after it has circulated through the body, offering insight into the body’s oxygen utilization.
O2 and CO2 levels on ABG vs mixed venous
PvO2 usually lower than arterial oxygen partial pressure (reflecting consumption by tissues)
PvCO2 slightly higher than arterial representing CO2 production from cellular metabolism
what does pulse oximetry measure?
oxygen saturation level of hemoglobin in the blood
how does the pulse ox probe work?
the probe emits light wavelengths through the skin and measures the amount of light absorbed by the oxygenated and deoxygenated blood hemoglobin. this data is then used to calculate the percentage of hemoglobin saturated with O2, displayed as SpO2 on device screen
end-tidal capnography (EtCO2) measures
partial pressure or concentration of carbon dioxide in exhaled breath at end of expiration
provides continuous graphical representation known as capnogram reflecting patient’s ventilatory status, perfusion, and metabolic activity
normal EtCO2 levels and indications if high or low
35-45 mmHg
high: hypoventilation, increased metabolic activity, decreased CO
low: hyperventilation, decreased metabolic rate, pulmonary embolism
describe the four phases of capnogram
1: baseline with no CO2 as fresh gas is inhaled
2. sharp rise as alveolar gas mixes with dead space gas
3. alveolar plateau, CO2 levels reach peak at end expiration
4. beginning of inhalation with rapid fall in CO2 levels
analyzing these phases helps identify ventilation-perfusion mismatches and airway obstructions
EtCO2 is especially helpful in the ICU for
intubation and CPR
titrating ventilator settings
accidental extubation
equipment malfunction
