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732 > Session 14 _ Arterial blood gases & Obstructive/ Restrictive lung disease > Flashcards

Session 14 _ Arterial blood gases & Obstructive/ Restrictive lung disease Flashcards

1
Q

PaO2 (PO2) =

A
  • Partial pressure of arterial oxygen

* amount of O2 in blood (both attached to Hgb and dissolved in plasma)

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2
Q

SaO2 =

A
  • amount of O2 bound to Hgb is related to PaO2

* If Hgb is low, SaO2 will be fine but PaO2 decreases

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3
Q

Alveolar ventilation is represented by PCO2, what is the normal range?

A

35-45mmHg

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4
Q

Hypoventilation =

A

retains CO2 (CO2 >40)

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5
Q

Hyperventilation =

A

blow off CO2 (CO2

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6
Q

In normal individuals without lung pathology, what happens if they hypoventilate? If they hyperventilate?

A

Hypoventilate - CO2 eventually causes respiratory center to stimulate increased ventilation
Hyperventilate - CO2 signals respiratory center to decrease ventilation

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7
Q

What is the normal value for PO2, PCO2 and pH?

A 
PO2= 80 
PCO2 = 40
pH = 7.4
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8
Q

what is the normal range for pH? PO2? PCO2?

A 
ph = 7.35-7.45
PO2 = 80-100 mmHg
PCO2 = 35-45 mmHg
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9
Q

Hypoxemia =
mild Hypoxemia =
moderate Hypoxemia =
severe Hypoxemia =

A

Hypoxemia =

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10
Q

When matching ventilation with the needs of the body, the goal is to maintain appropriate O2, CO2 and H+. What molecules are control mechanisms responsive to?

A
  • CO2 and H+

* O2

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11
Q

Central control of ventilation is known as the central chemoreceptors (medulla). What do they respond to?

A

increase PCO2, pH and CSF

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12
Q

Peripheral control of ventilation is known as the peripheral chemoreceptors. What do they respond to?

A

• Carotid bodies (cranial n. IX)
–> respond to decrease in PO2 or decreased pH
• Aortic bodies (cranial n. X)
–> respond to decreased PO2 or decreased pH

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13
Q

In the regulation of respiration, a decrease in PO2 causes:

A
  • little effect until drops 40% or below 60 mmHg

* if drops to 40 mmHg, then respiration increases only 50-60%

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14
Q

In the regulation of respiration, a increase in PCO2 causes:

A
  • if increases 10%
  • respiration increases by 2x
  • even if PO2 is normal
  • CO2 regulates respiratory activity under normal conditions
  • subject to adaptation
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15
Q

What are the affects of pulmonary disease on respiration?

A

• Retention of CO2 can occur (making it difficult to exhale; get pockets of air retained in alveoli)
• Example: Emphysema
•PCO2 chronically elevated (system adapts to elevated PCO2)
*** Therefore, reduced PO2 acts on peripheral chemoreceptors and provides main stimulus for respiration = hypoxic drive

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16
Q

Blood gas analysis provides information on:

A
  • Blood O2 levels through gas exchange
  • blood CO2 levels
  • pH- acid base balance or imbalance (*noted in extra-celluar fluid)
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17
Q

Blood gas analysis reflects oxygen status and acid-base balance needed to sustain life. pH

A

pH 7.8 is lethal
Acidic blood = force of cardiac contraction LESSENS
Alkaline blood = impaired neuromuscular function

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18
Q

What are the 3 processes in the body that regulate acid-base?

A 
1. chemical buffers 
•substances combining with acid or bases
2. respiratory system 
• regulates CO2 in the blood
• central chemoreceptors note change in pH - regulate rate and depth of breathing
3. renal system 
• slower system
• retain or excrete acids and bases to maintain equilibrium
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19
Q

Respiratory vs metabolic cause of acid base change=

A 
respiratory = lung dysfunction does not allowing to correct amount of CO2 to be exhaled
metabolic = something else going on in the body that is causing a build up of H+ -->  allow pH drop
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20
Q

How do you interpret blood gases?

A
  • Look at PCO2 to determine alveolar ventilation
  • Look at pH to see if normal acid-base balance and whether acute or chronic
  • Look at PO2 to determine oxygenation or hypoxemia and to what degree

To determine if acidosis or alkalosis and if cause is respiratory or metabolic

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21
Q

Is the patient on oxygen or mechanical ventilation with these values?

A

this is the question to ask yourself

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22
Q

If pH is 7.4 =

A

potential for acidosis

potential for alkalosis (more basic EN)

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23
Q

Elevators and see-saws: help to remember how pH and CO2 move in relation to each other. What is the see saw in metabolic dysfunction?
*****

A

metabolic dysfunction - pH decrease, CO2 (biocarbonate) goes down

24
Q

See-saw; if pH is going down –> CO2 increase =

A

respiratory cause

25
Q

In a metabolic elevator:

A
  • check pH
  • examine HCO3-
  • if metabolic, HCO3 will go in same direction as pH
  • Low pH and low HCO3- = METABOLIC acidosis
26
Q

What is an example of metabolic acidosis?

A

renal failure

27
Q

In a respiratory see-saw:

A
  • check pH
  • CO2 will go in opposite direction as pH is respiratory imbalance
  • RESPIRATORY acidosis low pH and high CO2
28
Q

Explain what occurs during respiratory failure:

A

•Inability to meet needs to body ( “the arterial oxygen, carbon dioxide or both cannot be kept at normal levels. A drop in the oxygen carried in blood is known as hypoxemia; a rise in arterial carbon dioxide levels is called hypercampia”
• pH below 7.30
• PCO2 above 50; usually also have hypoxemia
• Treatment includes: oxygen therapy and positive airway pressure
** Respiratory ventilation - airflow to help keep airways open (used with sleep apnea and with critically ill patients (ex. with end-stage COPD)

29
Q

What disease pathology causes patients to have respiratory failure?

A

COPD

30
Q

COPD and supplemental oxygen:

A
  • In emphysema, CO2 is retained in alveoli, equilibrates and is high in blood (long-term compensation)
  • pH can be in normal range, due to increased bicarbonate
  • set point for central chemoreceptors is higher than 40 mmHg (limited drive to breathe)
  • Low PO2 (hypoxia) allows for respiratory responses: EXCEPT if supplemental oxygen relieves hypoxia, then neither central or peripheral chemoreceptors are sensitive enough to improve respiration
  • Additional supplemental oxygen can lead to respiratory failure
31
Q

Patient example: COPD with PO2 75, PCO2 70 and pH 7.37; if add oxygen to relieve hypoxia and bring PO2 to 90, what happens?

A

patient has no stimulus to increase respiration

theoretically will stop breathing… because hypoxic drive is reduced

32
Q

List examples of conditions that impact the pulmonary system:

A

obstruction of the airway, drowning, lung cancer, scoliosis, asthma, premature birth, ruptured diaphragm, atelectasis, metabolic acidosis, interstitial lung disease (ILD), rib fracture, pneumothorax, tuberculosis, pneumonia, paralysis of respiratory mms
COPD, CO poisoning, EN (asbestos…)

33
Q

Pulmonary disease is a leading cause of morbidity and mortality. There are two types of pulmonary disease; obstructive and restrictive. What is obstructive characterized by?

A
  • airflow obstruction
  • increased airway resistance
  • often affects expiratory flow rate
34
Q

Pulmonary disease is a leading cause of morbidity and mortality. There are two types of pulmonary disease; obstructive and restrictive. What is restrictive characterized by?

A
  • reduced lung compliance
  • reduced thoracic compliance
  • often affects inspiratory volume
  • •less elasticity
35
Q

List obstructive lung disease:

A
  1. chronic bronchitis
  2. emphysema
  3. bronchiectasis
  4. Asthma
    (5. CF)
36
Q

List restrictive lung diseases:

A
  1. Interstitial lung disease

2. Idiopathic Pulmonary fibrosis (IPF)

37
Q

In pulmonary function tests (PFTs)
Normal =
Obstructive =
Restrictive =

A

Normal = FEV1 = 3 L / FVC 4L / ration 75%
Obstructive = FEV1 = 1 L / FVC 4L / ration 25%
Restrictive = FEV1 = 2.5 L / FVC 3L / ratio 83%
(no difficulty getting air out, but the volume only goes up to 3 L; can’t get as much air in so —> ratio is higher)
** ratio of a restrictive disease is usually higher than 80%

38
Q

In pulmonary function tests, what is normal ratio?

A

75%

39
Q

Describe the typical characteristics of obstructive lung disease?

A
  • 3rd leading cause of death in the US
  • US estimated 12.7 million diagnosed with obstructive lung disease
  • > women dies from diagnosis of COPD than men
  • smoking is the primary risk factor for COPD
40
Q

What do we see in radiographs of individual with obstructive diseases:

A

•flattened diaphragm
•hyper inflated lungs due to air trapping
• Enlarged heart with enlarged right ventricle
• barrel chest - sign of lung disease
• may see small pockets of air (1-2 cms) = blebs
(due to the destruction of alveoli)
• if bleb pops, air goes into pleural cavity
•elasticity lost, walls become fragile
• bullae = > 2 cm of air

41
Q

What are some potential consequences of obstructive lugs disease:

A

• destruction of lung tissue resulting in emphysema
• inflammation of airways
•pulmonary hypertension (getting blocked –> less capilaries and arterioles for blood to flow through –> less area for blood to flow through
(* develop it from L side HF or idiopathic –> blood can’t go from lung to heart, get back flow in lung –> dmanage and increase pressure)
• hypoxemia
• dysrhythmias
•sleep disorders
• repeated infections
• build up of secretions

42
Q

Consequences (continued):

A
  • polycythemia
  • adaptation to chronically low O2
  • sluggish blood flow
  • right heart failure
  • resistance to air flow-increased work of breathing
  • normal or increased lung capacity
43
Q

Example of COPD: Chronic Bronchitis. Diagnosis =

A

greater than 3 months of productive cough most days in for at least 2 consecutive years

44
Q

Example of COPD: Chronic Bronchitis. Causes =

A
  • irritation of the bronchial tree; risk factor - smoking or exposure to smoke
  • genetics
  • exposure to particles (EN hazards, occupational dust, indoor air pollution, outdoor air pollution, respiratory infections, alpha 1 antitryspin disorder)
45
Q

S and S of obstructive lung disease:

A
  • secretion production
  • reduced cilia action leading to build up of secretion and bacteria
  • repeated infection, pneumonia
  • hypoexemia
46
Q

Emphysema = end stage COPD; defined =

A

abnormal, permanent increased size of air spaces distal to terminal bronchioles by the destruction of alveolar walls

47
Q

What other changes occur during end stage COPD?

A
  • alveolar destruction
  • over-inflation of the lungs
  • lungs cannot empty (expiration)
  • emphysematous bullae
  • chronic hypoxia and hypercapnea

** surgical Rx: potential for lung reduction surgery

48
Q

What are some characteristics of restrictive lung disease:

A
  • decreased expansion of the lung
  • decreased total lung capacity
  • Hypoxemia [examples = disease of pleura (pneumothorax), disease of chest wall (kyphoscoliosis, obesity - lungs expand), extrapulmonary mass restricting the expansion of lungs)
  • rupturing blebs –> more resistance to filling lungs
  • stiffening of the lung tissue preventing expansion
  • structural limitations preventing lung inflation: examples anklylosing spondylosis, kyphoscoliosis, obesity.
  • Interstitial lung disease (ILD)
  • Pleural abnormalities “trapped lung”
  • Mass
  • Systemic lupus erythematosus (SLE)
  • Pneumothorax
  • Connective tissue disease - scleroderma
  • Radiation therapy
  • Idiopathic pulmonary fibrosis (IPF)
49
Q

what is ankylosing spondylosis?

A

fused not, much movement or expansion

50
Q

What are characteristics of pulmonary fibrosis?

A
  • Onset middle age (50-70)
  • 4-5 years mean life expectancy
  • Increased respiratory rate (30-40)
  • Hypoxemia, cyanosis - GIVE OXYGEN
  • treat inflammation before turns to fibrosis (corticosteroids)
51
Q

What are some medical treatments for lung diseases?

A
  • steroids - usually for presence of inflammation
  • antibiotics - for presence of infection
  • oxygen - to treat hyoexemia
  • inhalers - for bronchospasm
  • assisted ventilation - invasive or non-invasive
  • lung transplant
  • lung reduction surgery - to make smaller pockets where air can sit
52
Q

Is there a measure for SaCO2?

A

no convenient non-invasive measure

53
Q

What should a typical PT assessment include?

A
  • O2 ned at rest
  • O2 need for activity
  • Blood gases PaO2, PaCO2, pH
  • Auscultation
  • RR
  • Breathing patterns (symmetrical?)
  • Endurance
  • Perceived exertion
  • timing of rest breaks
  • time to return to baseline HR and RR
  • Safe exertion levels
  • O2 saturation
  • O2 requirements as evidence by O2 saturation
  • Gait safety
  • Prior level of function? Prior O2 use
  • Education needs, such as not tripping on O2 cords
  • Need for lifestyle changes ??
  • Psychosocial influences affecting potential outcomes
54
Q

** PRECAUTIONS**

A
  • people w/ chronic lung disease may have chronic hyoxemia. A certain level of hypoxemia is required to trigger inspiration. Over oxygenating these patients may decrease their inspiratory drive
  • Target O2 sat is lower than usual: 88-92%
  • Time to return to steady state may be prolonged
  • Few or no symptoms at low O2 saturations - Low O2 saturation will overtax the heart and result in cell death and maybe actual death
55
Q

** ALERTT*** w/ • ILD and O2 desaturation

A
  • Monitor w/ a pulse oximeter from the start if you have a with diagnosis of ILD
  • Be prepared to see O2 saturation drop like a rock with minimal activity
  • Always have access to a full O2 tank
  • Ambu-bag
56
Q

List some PT treatments:

A
  • breathing control - diaphragmatic, PLB
  • pacing skills/ work simplification
  • endurance training
  • strengthening
  • education e.g. O2 management, fatigue scale
  • confidence building
  • Carefully include those with: older age, hypercapnia, severe impairment
  • Patient’s own goals: couch vs marathon?

732 (12 decks)

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