Exam Review Module 2: Oxygen supply & demand

Internal respiration

Exchange of gas between capillaries and the cells of the body (oxygen is delivered and carbon dioxide is removed)

External respiration

exchange of gases between the alveoli and the lung capillaries (between air and blood)

True or false: A decrease is PaCO2 indicates an increase in ventilation

true

True or false: Veins contain approximately 75% of circulating blood volume?

Ture

Atrioventricular valves are:

Tricuspid and mitral values

Where is the mitral valve located (between which 2 structures)?

The Left atrium and the Left ventricle

When the patient’s hemoglobin levels decrease, does their SpO2 or SaO2 decrease?

No, it will not decrease because the amount of O2 bound to hgb will not change, just the number of available hgb.

What does aldosterone do in the RAAS?

Causes Na+ and H20 retention

True or false: Peripheral nervous system activity results in slowing the HR

True

What does angiotensin II in the RAAS activate?

Vasoconstriction

What do the Beta 1 receptors do?

Increased contractility, increased HR and increased conductivity

What receptors are responsible for bronchodilation and peripheral vasodilation?

Beta 2

Which receptors are responsible for vasoconstriction (smooth muscle contractions)?

Alpha receptors

The peripheral chemoreceptors respond to a decrease in:

PaO2

What is the role of ACE in the RAAS?

Convert angiotensin I to angiotensin II

What are the 3 factors that influence arterial oxygen saturation:

1. Concentration of O2 in the inspired gas (FiO2) ( consider use supplemental O2?)

2. Individual’s ability to get air in and out of lungs (ventilation)

3. The effectiveness of gases moving across the A-C membrane (gas exchange)

The two key factors that influence ventilation are:

1. Resp rate

2. Tidal volume

How do you assess tidal volume?

auscultation of depth of breath sounds

When tidal volume is decreased, what happens to the resp rate?

increases to compensate

Factors that influence ventilation and WOB are:

1. Respiratory muscle function

2. Lung compliance

3. airway resistance

How do you assess Respiratory muscle function (RMF)?

• older age

• poor nutrition

• tiredness and exhaustion

• generalized muscle weakness/fatigue

• accessory muscle use

• increased WOB

• lack of use (mechanical ventilation)

• Weak cough (muscle is weak)

** pain is NOT an assessment cue for RMF

Assessment cues for decreased lug compliance:

• increased WOB

• increased resp rate

• decrease in tidal volume

• Mucus and secretions

• inflammation

• consolidation

• fibrosis

• Productive cough

• pink, frothy sputum

• thick, yellow sputum

• fine or coarse crackles on auscultation

• audible crackles (without a stethoscope)

• pulmonary edema

• lung infections

• atelectasis

• spinal deformities

• circumferential chest burns

• Chest xray findings: wet-looking lungs, edema, infiltrates, consolidation, pneumonia, COPD, fibrosis and ARDS

assessment data for increased lung compliance:

1. emphysema (big and baggy lungs)

2. Flail chest (lungs expand beyond chest wall)

Increased airway resistance assessment cues:

• broncho constriction

• asthma attack

• wheezes

• stridor

• inflammation

• airway edema/swelling

• thick mucus AND mucous plugs

• lots of secretions that fill the airway

• airway obstruction (partial/complete)

• artificial airways (tracheostomy; oral endotracheal tubes)

• broncho spasms

What is tidal volume? What is the normal amount?

the amount of air that moves in and out of the lungs with one respiratory cycle during a normal breath at rest.

normal: 400-500mL

How do you assess Vt?

• auscultation of breath sounds to bases

• Decreased breath sounds indicate shallow breathing

• shallow breathing can be visualized by lack of movement of the ribs

• fast resp rate lead to shallow breaths and therefore less time to completely inflate lungs

• Atelectasis on chest x-ray due to shallow breathing

• pain (chest, abdo) can lead to shallow breathing

• rib fractures, chest tubes

What is vital capacity?

is the total amount of air forcefully expelled from the lungs after maximum inhalation

How do you assess VC?

• resp muscle function

• cough strength

• trends in VC volume numbers

• conditions and diseases that decrease respiratory muscle strength —> such as spinal cord injury and late stages of multiple sclerosis, guillain barre syndrome and ALS

What does Vital capacity assess for in patients?

if a patient can protect their own airway (good indicator of resp muscle strength)

What is FRC? Normal range?

Volume of air remaining within the lungs after passive exhalation at rest.

• Indicates how many alveoli remain open at the end of exhalation; the larger the FRC, the less WOB

Normal range: 2400-3000mL in healthy ppl

Assessing the FRC:

• resp muscle function

• prolonged decreased breath sounds

• prolonged shallow breathing

• atelectasis on chest x-ray

True or false: Ventilation is normal if PaCO2 is normal, despite abnormal findings in compliance, resistance, Vt and RMF

True

Increased ventilation is when the PaCO2 is ____

decreased

Decreased ventilation is when: the PaCO2 is ____ and ___ are abnormal or RR is ___

Increased and lung compliance, airway resistance, Vt and RMF are abnormal

Or RR is decreased and PaCO2 is increased

Assessment of ventilation:

• lung auscultation

• WOB

• RR

• admitting diagnosis

• patient position

Auscultation sounds tell you that…

1. crackles

2. decreased breath sounds to bases…

3. Wheezes

1. decreased compliance

2. decreased Vt

3. increased airway resistance

Increasd RR during compensation can ___ventilation and can ____ PaCO2

increase and decrease

If the only issue with ventilation is decreased RR, it can be concluded that ventilation is ___, even without PaCO2

decreased

Interventions to increase ventilation:

• DB+C

• Incentive spirometry to increase Vt

• chest physio - remove secretions and increase compliance

• BiPAP (IPAP) to improve Vt and augment ventilation

• Bronchodilators to open up airways and reduce airway resistance

• Positioning: High fowlers to reduce WOB and increase Vt and improve V/Q matching & more ventilation to bases

when lung compliance, RMF and PaCO2 are decreased, ventilation is ___

increased

Right shift of ODC:

• Elevated PaCO2

• pH acidotic (below 7.35)

• Elevated temperature

• Elevated 2,3 DPG

Left shift of the ODC:

• Decreased PaCO2

• pH alkolosis (above 7.45)

• Decreased temperature

• Decreased 2,3 DPG

What happens to affinity with right shift?

Decreases; O2 molecules are readily released from hgb

What happens to affinity with a left shift?

Increases; O2 molecules stay attaches to hgb and do NOT release easily from hgb

When a patient has a normal afterload, preload is…

normal

When afterload is increased, what happens to preload?

It is increased

When afterload is decreased, preload is…

decreased

When preload is decreased, afterload is…

increased to compensate

How does afterload indirectly impact contractility?

When afterload is increased, preload increases which increases contractility

When afterload is decreased, preload decreases which decreases contractility

How does afterload directly impact contractility?

When afterload increases due to vasocontriction, the resistance the heart has to pump against increases → the SNS is activated, which increases contractility

When preload is normal, contractility is___

normal

When preload is increased, contractility is ___

increased

When preload is excessively increased, contractility is ___

decreased

When preload is decreased, contractility is ___

decreased

Preload can directly affect contractility, but can contractility directly affect preload?

Yes; contractility is decreased when ventricular compliance is decreased … when contractility is decreased, preload is increased