cardiopulmonary review Flashcards by Jessica Ernst

Mean Arterial pressure equals what?

Cardiac output X systemic vascular resistance

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What is MAP=CO X SVR good for?

fixing hypotensive patients

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electrophysiology

electrical activity required for mechanical activity to occur

excitation-contraction coupling

distribution of Na, K, Cl, and Ca responsible for electrical potential across cell membranes

normal distribution of ions required for normal electrical activity to occur

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What does 0 represent?

rapid inward Na flux

rapid depolarization

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What does 1 represent

transient outward K+ flux

initial repolarization

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What does 2 represent?

large, slow inward Ca flux

triggers cellular Ca release

cell contracts

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what does 3 represent?

Outward K flux

repolarization

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What does 4 represent

resting phase

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What does 0 represent

slower inward Na and Ca flux

slower rate of depolarization

pacemaker cells

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What does 2 represent

large slow inward Ca flux

trigger cellular Ca release

cell contracts

pacemaker cells

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What does 3 represent?

outward K flux

repolarization

pacemaker cells

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What does 4 represent?

Slow inward Na flux

slow depolarization

pacemaker cells

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diastolic depolarization

SA & AV node, purkinje system

resting potential gradually depolarizes

reaches threshold, triggers action potential

cardiac tissue with the most rapid rate of rise of phase 4 determines heart rate

Usually SA node

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excitation contraction coupling

calcium

Action potential (phase 2)–>inward Ca flux

trigger Ca release from sacroplasmic reticulum

Ca binds to troponin C

Actin and myosin can now interact

cell contracts

strength of contraction depends on amount of Ca

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What interferes with excitation contraction coupling and Ca?

inhalants

increase phase 2 of action potential

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What is most important in delivering oxygen to tissues?

Hemoglobin

What pathophysiologies affect delivery of oxygen?

Anemia

Low CO (low MAP)

Acid-base imbalances

hypothermia

Blood pressure

best measurement of perfusion

MAP=CO X SVR

Cardiac output equals?

heart rate X stroke volume

What is stroke volume affected by?

preload

afterload

contractility

At what bp would a small animal patient be considered hypotensive?

<60 mmHg

At what bp would a large animal patient be considered hypotensive?

<70 mmHg

maintain perfusion to skeletal muscles

At what bp would a small animal renal patient be considered hypotensive?

<70 mmHg

At what bp would a hypertensive patient be considered hypotensive?

try to keep within 20% of normal for that patient

What affects cardiac output?

most anesthetics arrhythmias contractility decreased preload low SVR automaticity effects

What increases automaticity of the heart?

tachycardia hyperthermia hypoxia hypokalemia hypercalcemia catecholamines

inspiration

slight negative intrathoracic pressure active process (diaphragm, external intercostal) augments venous return

expiration

slight positive pressure passive or active process (internal intercostals, horses, reptiles, birds)

Goals of Ventilation

Gas exchange! CO2 removal Oxygenation of Hemoglobin

control of ventilation

central: pons and Medulla Chemoreceptors

central control of ventilation

pons: pneumotaxic center, apneusti center Medulla: Dorsal respiratory group, ventral respiratory group

chemoreceptor control of ventilation

Oxygen, CO2 and H concentrations peripheral chemoreceptors: Carotid body, aortic bodies Central Chemoreceptors: sense CO2, BBB less permeable to H+

5 reasons for hypoxemia

low inspirated O2 (FiO2) Hypoventilation diffusion impairment ventilation/perfusion mismatch shunt

V/Q mismatch

Normal lung has a range of V/Q matching Well ventilated but no perfusion--\>physiologic dead space, V/Q=infinity no ventilation/well perfused--\>shunt, V/Q = 0