AHN 572
AHN 572 RESPIRATORY EXAM 1 2025
What causes shift to right? - -it is a decreased hbg affinity for o2. Hgb lets go of o2 at
tissues.
-acidosis- increased co2
-pregnancy
-hyperthermia
-increased 2,3, dpg (arterial hypoxemia, chronic anemia, pregnancy, hormones [epi,
thyroxine, gh, testosterone]
-chronic anemia-sickle cell anemia
-tissue hypoxia releasing acid facilitates o2 release and co2 binding
What causes shift to left? - -increased hgb affinity for o2. Less o2 is unloaded at tissues.
-hgb hold on o2 when youre cold. Hypothermia.
-alkalosis-decreased co2
-decreased 2,3, dpg bc less stored rbc. And hypophosphatemia causes low 2,3 dpg.
-hbg dysfunction- fetal hemoglobinameia, methaemoglobin, carboxyhaemoglobin.
-carbon monoxide poision-spo2 will be 100% bc hgb 100% saturate with monoxide.
-hypophosphatemia-rbc dysfunction and low levels of 2,3 dpg.
* all these perpetuate tissue hypoxia*
Normal value of pft? - -value greater than 70% of predicted volume & >80% pefr flow
rate
Mildly reduced pft - -mild= 60-70% of predicted volume/flow rate
Moderately reduced pft - -50-60% of predicted volume/flow rate
Severely reduced pft? - -<50% predicted volume/flow rate
Diagnostic of air trapping or hyperinflation on pft? - -rv and tlc exceeds 120% of
predicted value
Residual vol- vol left after expire
Tlc- total expired vol
Green zone on pefr - -peak expiratory flow rate on flowmeter
80-100% expected volume, maintain or reduce meds, or no change needed
Yellow zone on pefr - -50-80% of baseline
increase therapy or in acute exacerbation then additional therapy should be added
Red zone on pefr - -<50% form baseline
if still in distress after treatment give epinephrine and call 911
Key to diagnosing obstruction from pft - -obstruction has high residual volume rv and
AHN 572
,AHN 572
Fvc is >80% but fev1/fvc is <0.7.
O2 goals - --if hypoxemia exists, use o2 for goal 90-94% spo2.
-if >96% then wean o2.
-if hypercapnia risk: 88-92%
-100% o2 for cluster ha, ptx, sickle cell crisis, carbon monoxide poison
-no o2 for stoke or mi unless spo2 <90%
Bernoulli's principle and nc liter capability. - -o2 in nose is pulled to trachea irregardless
of mouthbreathing with nc on
Nc 1-6l.
Add 4% with every l to 21% ra. If using >4l then consider different therapy.
-doesn't cause breathing of co2.
Pro and con of simple face mask - -pro: 5-8l, 40-60% fio2
Con: air is trapped under mask and imprecise.
Not ideal for copd, aspiration risk pt.
Venturi mask ability and pros - -up to 40l, 60% fio2
Very precise because there is no airtrapping. Fio2 doesn't very with flow rate and
breathing pattern.
Ideal for hypercapnia pt not rebreathe and o2 is exact.
Non-rebreather pro and con
Liter amount - -11-15l, almost 100%
One way valve allows for exhaled co2 to not be inhaled again.
Inflate then collapse 1/3-watch bag amount
Con-no humidification and o2 toxicity atelectasis risk
High flow nc- optiflow, vapotherm
Liter and fio2 - -up to 60l
21-100% fio2
1st line tx for hypoxic resp failure, chf, ards. Reduced intubation occurrences with early
application.
(humidified and heated)
Oxygen toxicity can cause what? - -1. Tracheobronchitis- substernal chest pain
2. Hypercapnic resp failure-copd
3. Absorption/alveolar atelectasis- collapse proximal airway with air trap in alveoli
4. Coronary vasoconstriction from hyperoxia
Increased hbg affinity for o2 means? - -less unloading of o2 at tissues by hbg
Weak hbg affinity for 02 means? - -hgb readily disassociates with o2 when pao2 falls
below 60
AHN 572
,AHN 572
Left shift causes? - -sa2 value is higher than normal predicted for the given pao2.
Less o2 released at tissues but more o2 is bound to hbg in lungs.
Right shift causes? - -is causes hbg affinity for o2 at given pao2 on curve to go down,
and sao2 value decreased below normal
O2 is easily delivered to tissues if pt is getting enough o2 from lungs.
Is pa02 is 40-60? What to do? - -supplemental o2 significantly helps increase sa02
5 causes of hypoxia - -1. Hypoventilation
2. V/q mismatch
3. Right to left shunt
4. Diffusion limitation
5. Reduced inspired oxygen tension-high alt
Causes of hypoventilation? (hypoxia) - -cns depression-od, neuro compromise
Obesity-
Musculoskeletal weakness- gillian barre, muscular dystrophy, spinal cord injury
Hypothyroid
Causes of v/q mismatch (hypoxia) - -*most common reason for hypoxemia*
*most responsive to o2 therapy*
Perfusion or ventilation to alveoli are altered
Shock, low co
Pe
Obstructive lung dz-copd, emphysema
Interstitial edema
Causes of right to left shunt (why extreme hypoxemia?) - -anatomic-alveoli are
bypassed- intracardiac shunt like pfo, pulmonary avm, hepatoplumonary shunt
2. Physiologic shunt- nonventilated alveoli are perfused- pna, atelectasis, pus, blood in
alveoli.
Extreme hypoxemia from extreme mismatch in perf and vent. Dead space is hard to
oxygenate so profound hypoxemia.
This is less responsive to o2 therapy when shunt is greater >than 20%
What causes diffusion limitation? (hypoxmemia) - -interstitial lung disease
Exposure, medication, autoimmune, idiopathic reason for fibrosis and scarring.
The o2 movemnt from alveoli to capillaries is impaired causes a v/s mismatch. Diffusion
limitation and v/q mismatch often coexist.
AHN 572
, AHN 572
What causes reduced inspired oxygen tension? - -high altitude causes reduction in a-a
gradient causing hypoxia
X axis of curse is what? - -po2 80-100
Critical is less than 60
Y axis of curse is what? - -oxyhemoglobin percentage concentrated
Normal 95-100%
Po2 40=
Po2 50=
Po2 60= - -po2 40= 70% sat
Po2 50=80% sat
Po2 60= 90% sat
How to diagnose asthma - -1. Spirometry with airflow limitation
-reduced, fev1, fev1/fvc ratio,
-reduced peak expiratory flow (pef)
2. Symptoms: wheeze, dyspnea, cough
-prolonged expiration and diffuse wheezes
-increased sputum
-diminished breath sounds
-allergic s/s/
3. Positive broncoprovacation challenge
Where bronchodilator reverses airflow obstruction
Treatment of mild asthma exacerbation - -minor change in peak expiratory flow. Still
>80% overall.
1. Saba at increased dose
2. Po steroid if already taking daily inhaled steroid
Tx of moderate asthma exacerbation - -peak exp flow <70% needs steroids.
1. Saba
-(how much pef improves after 30min is severity of exacerbation)
2. Systemic steroids
3. Correct hypoxemia, reverse the obstruction
Try to prevent this reoccurance by stepping up therapy and adding meds. Consult
asthma specialist steps 3-6.
How to treat a severe asthma attack? - -o2
Saba
Steroids + ipratroprium
Iv magnesium
No mucoylytics
Abx if indicated
AHN 572
AHN 572 RESPIRATORY EXAM 1 2025
What causes shift to right? - -it is a decreased hbg affinity for o2. Hgb lets go of o2 at
tissues.
-acidosis- increased co2
-pregnancy
-hyperthermia
-increased 2,3, dpg (arterial hypoxemia, chronic anemia, pregnancy, hormones [epi,
thyroxine, gh, testosterone]
-chronic anemia-sickle cell anemia
-tissue hypoxia releasing acid facilitates o2 release and co2 binding
What causes shift to left? - -increased hgb affinity for o2. Less o2 is unloaded at tissues.
-hgb hold on o2 when youre cold. Hypothermia.
-alkalosis-decreased co2
-decreased 2,3, dpg bc less stored rbc. And hypophosphatemia causes low 2,3 dpg.
-hbg dysfunction- fetal hemoglobinameia, methaemoglobin, carboxyhaemoglobin.
-carbon monoxide poision-spo2 will be 100% bc hgb 100% saturate with monoxide.
-hypophosphatemia-rbc dysfunction and low levels of 2,3 dpg.
* all these perpetuate tissue hypoxia*
Normal value of pft? - -value greater than 70% of predicted volume & >80% pefr flow
rate
Mildly reduced pft - -mild= 60-70% of predicted volume/flow rate
Moderately reduced pft - -50-60% of predicted volume/flow rate
Severely reduced pft? - -<50% predicted volume/flow rate
Diagnostic of air trapping or hyperinflation on pft? - -rv and tlc exceeds 120% of
predicted value
Residual vol- vol left after expire
Tlc- total expired vol
Green zone on pefr - -peak expiratory flow rate on flowmeter
80-100% expected volume, maintain or reduce meds, or no change needed
Yellow zone on pefr - -50-80% of baseline
increase therapy or in acute exacerbation then additional therapy should be added
Red zone on pefr - -<50% form baseline
if still in distress after treatment give epinephrine and call 911
Key to diagnosing obstruction from pft - -obstruction has high residual volume rv and
AHN 572
,AHN 572
Fvc is >80% but fev1/fvc is <0.7.
O2 goals - --if hypoxemia exists, use o2 for goal 90-94% spo2.
-if >96% then wean o2.
-if hypercapnia risk: 88-92%
-100% o2 for cluster ha, ptx, sickle cell crisis, carbon monoxide poison
-no o2 for stoke or mi unless spo2 <90%
Bernoulli's principle and nc liter capability. - -o2 in nose is pulled to trachea irregardless
of mouthbreathing with nc on
Nc 1-6l.
Add 4% with every l to 21% ra. If using >4l then consider different therapy.
-doesn't cause breathing of co2.
Pro and con of simple face mask - -pro: 5-8l, 40-60% fio2
Con: air is trapped under mask and imprecise.
Not ideal for copd, aspiration risk pt.
Venturi mask ability and pros - -up to 40l, 60% fio2
Very precise because there is no airtrapping. Fio2 doesn't very with flow rate and
breathing pattern.
Ideal for hypercapnia pt not rebreathe and o2 is exact.
Non-rebreather pro and con
Liter amount - -11-15l, almost 100%
One way valve allows for exhaled co2 to not be inhaled again.
Inflate then collapse 1/3-watch bag amount
Con-no humidification and o2 toxicity atelectasis risk
High flow nc- optiflow, vapotherm
Liter and fio2 - -up to 60l
21-100% fio2
1st line tx for hypoxic resp failure, chf, ards. Reduced intubation occurrences with early
application.
(humidified and heated)
Oxygen toxicity can cause what? - -1. Tracheobronchitis- substernal chest pain
2. Hypercapnic resp failure-copd
3. Absorption/alveolar atelectasis- collapse proximal airway with air trap in alveoli
4. Coronary vasoconstriction from hyperoxia
Increased hbg affinity for o2 means? - -less unloading of o2 at tissues by hbg
Weak hbg affinity for 02 means? - -hgb readily disassociates with o2 when pao2 falls
below 60
AHN 572
,AHN 572
Left shift causes? - -sa2 value is higher than normal predicted for the given pao2.
Less o2 released at tissues but more o2 is bound to hbg in lungs.
Right shift causes? - -is causes hbg affinity for o2 at given pao2 on curve to go down,
and sao2 value decreased below normal
O2 is easily delivered to tissues if pt is getting enough o2 from lungs.
Is pa02 is 40-60? What to do? - -supplemental o2 significantly helps increase sa02
5 causes of hypoxia - -1. Hypoventilation
2. V/q mismatch
3. Right to left shunt
4. Diffusion limitation
5. Reduced inspired oxygen tension-high alt
Causes of hypoventilation? (hypoxia) - -cns depression-od, neuro compromise
Obesity-
Musculoskeletal weakness- gillian barre, muscular dystrophy, spinal cord injury
Hypothyroid
Causes of v/q mismatch (hypoxia) - -*most common reason for hypoxemia*
*most responsive to o2 therapy*
Perfusion or ventilation to alveoli are altered
Shock, low co
Pe
Obstructive lung dz-copd, emphysema
Interstitial edema
Causes of right to left shunt (why extreme hypoxemia?) - -anatomic-alveoli are
bypassed- intracardiac shunt like pfo, pulmonary avm, hepatoplumonary shunt
2. Physiologic shunt- nonventilated alveoli are perfused- pna, atelectasis, pus, blood in
alveoli.
Extreme hypoxemia from extreme mismatch in perf and vent. Dead space is hard to
oxygenate so profound hypoxemia.
This is less responsive to o2 therapy when shunt is greater >than 20%
What causes diffusion limitation? (hypoxmemia) - -interstitial lung disease
Exposure, medication, autoimmune, idiopathic reason for fibrosis and scarring.
The o2 movemnt from alveoli to capillaries is impaired causes a v/s mismatch. Diffusion
limitation and v/q mismatch often coexist.
AHN 572
, AHN 572
What causes reduced inspired oxygen tension? - -high altitude causes reduction in a-a
gradient causing hypoxia
X axis of curse is what? - -po2 80-100
Critical is less than 60
Y axis of curse is what? - -oxyhemoglobin percentage concentrated
Normal 95-100%
Po2 40=
Po2 50=
Po2 60= - -po2 40= 70% sat
Po2 50=80% sat
Po2 60= 90% sat
How to diagnose asthma - -1. Spirometry with airflow limitation
-reduced, fev1, fev1/fvc ratio,
-reduced peak expiratory flow (pef)
2. Symptoms: wheeze, dyspnea, cough
-prolonged expiration and diffuse wheezes
-increased sputum
-diminished breath sounds
-allergic s/s/
3. Positive broncoprovacation challenge
Where bronchodilator reverses airflow obstruction
Treatment of mild asthma exacerbation - -minor change in peak expiratory flow. Still
>80% overall.
1. Saba at increased dose
2. Po steroid if already taking daily inhaled steroid
Tx of moderate asthma exacerbation - -peak exp flow <70% needs steroids.
1. Saba
-(how much pef improves after 30min is severity of exacerbation)
2. Systemic steroids
3. Correct hypoxemia, reverse the obstruction
Try to prevent this reoccurance by stepping up therapy and adding meds. Consult
asthma specialist steps 3-6.
How to treat a severe asthma attack? - -o2
Saba
Steroids + ipratroprium
Iv magnesium
No mucoylytics
Abx if indicated
AHN 572
