PFT Flashcards
What pts are at risk for PPC?
Hx of significant pulmonary disease
Obesity
Aortic, thoracic, abdominal surgery
Long term smokers
Elderly (>70)
High risk PFT results: FEV1, FEV1/FVC, VC
<2L
<.5
< 40-50% predicted (15cc/kg in adults, 10cc/kg in children)
What % improvement in PFT is good?
15
How to treat bronchospasm and infections preoperatively
Bronchodilators
ABX, culture and senstivity
IE ratio for COPD pt
BIGGER
1:2 to 1:3!
What level to keep etco2 in co2 retainers? What if you dont?
Baseline, if not, you will cause metabolic alkalosis
What drugs to avoid in bronchospasm?
Histamine releasing drugs
STP (penthotal, barbituate for induction),
ABX,
neostigmine,
morphine/meperdine,
atracurium/succ/mivacurium,
Possibly aspirin, and if so then ketoralac
Only use albuterol, ketamine
If FEV1 is less than ___% of predicted, extubation will not be effected
50
If FEV1 is __% - __% of predicted, with some hypoxemia and hypercarbia, prolonged extubation is probably
25-50
If FEV1 is less than 25% what procedures should be done?
only life saving procedures
use regional if possible
Risk: inability to wean ventilator, trachestomy
Extubation criteria; RR, PaO2, PaCO2, MIF, VC
<30
>70 (on fio2 .4)
<55
less than -20cmH2o
>15cc/kg
Intubation criteria for acute respiratory failure; rr, vc, MIF, pao2, paco2, vd/vt, aa gradient, and clinical diagnosis’
> 35
<15cc/kg or 10cc/kg
-20cm h20
<70 on fio2 .4
55 (unless chronic)
.6
350mmHg on fio2 1.0
burns, AMS, rapid deterioration, fatigue
ABCs if CXR
airway
bone
cardiac
diaphragm
equal fields of lungs
gastric
hilum
invasive lines
How soon does an ABG need to be measured? What will happen if not?
15 minutes, glycolysis with lactic acid production, decreased ph, increased pco2
How long can i store abg on ice?
2h
What will heparin do to abg
lower PCO2 by dilution, especially in children with small samples
ABG normal values, ph, pco2, po2, hco2, base excess
7.35-7.45
35-45
70-105
22-27
-3 - 3
How does PCO2 effect ph
pco2 increase by 10, ph drop by .08
vice verse
Alveolar gas equation/ AA gradient equation
PAO2=(Pb-Ph2o)x(fio2)-(paco2/rq)
PaO2= from abg
What increases AA gradient?
GA
PTX
PE
shunt
VQ MM
When is AA gradient normal? in disease processes
hypoventilation, low fio2
How to treat high Aa?
fio2
PEEP
How does bicarb effect ph?
Increase in bicarb by 10mmoles increases ph by .15 (stronger than pco2)
What causes respiratory acidosis?
CNS depression from trauma or drugs
Obesity PF
COPD asthma
Causes of respiratory alkalosis
hypoxic respiration
encephalitis
anxiety
pregnancy
mech ventilation
Metabolic alkalosis causes
bicarb infusion
excessive vomiting
NGT suctioning
FRC in ml
2300
IC in ml
3500
vc in ml
4600
TLC in ml
5800
what % of TLC is FRC?
40%
FEV1 normal range
4L or 75% (if fev1 frc ratio)
What is the most important tool in assessing the severity of obstructive airway disease?
FEV1 will decrease to below 20% with acute asthma
Most sensitive marker of small airway disease?
FEF 25 75
Degree of risk in OLD, FEV1FRC
Normal- >75
Mild- 60-75
moderate- 45-60
severe- 35-40
extreme- <35
What is the use of flow volume loops?
Helps distinguish extrathoric/ intrathoracic diseases
ALSO
Helps distinguis from OLD vs RLD
FV loop normal
Semi circle on bottom (inspiration right to left)
Line up and angled right, and start line back to starting point (expiration)
What PFT has been shown to predict increased mortality in pts undergiong thoracic surgery?
MMV/ MBC
Maximum voluntary ventilation
What % fef 25 75 is considered confirmation of airway obstruction?
60
WITH
FEV1 FVC low or normal
FV loops intrat vs extra thoracic
Extra thoracic- top heavy
Intrathoracic- bottom heavy
(extra- you can see, it, intra, underground, cant see)
FV loops L or R shift
L shift- OLD
R shift- RLD
PFTs that indicate airway obstructions
FEF 25 75- less then 60% predicted
AND
FEV1:FVC- low (or normal)
What PFT, when decreased, has a high correlation with mortality and morbidity?
MMV max minute ventilation
MBC mac breathing capacity
Patho of extra vs intrathoracic disease? what do each mean?
Extra- obstruction
Intra- lung disease
Most important PFT for assessment of severity of OLD?
FEV1
How to differentiate OLD from RLD (PFT)
FEV1 FVC ratio
What conditions (bad) dont stimulate HPV?
Anemia/ CO poison
PaO2 stays normal
Extrathoracic vs intrathoracic obstruction effect on inspiratory vs expiratory flow
Extra- inspra
Intra-extra
Extra blocks inspiration
Intra block expiration
Fixed FV loop shape and cause
Its a small rectangle around the line
Tracheal stenosis
Metabolic acidosis causes
Lactic acidosis
DKA
ASA
high protein intake
Bicarb loss from diarrhea
When (how soon) does renal compensation occur after respiratory acidosis
1-2 days after
