pulm function tests Flashcards
PFT is usually
spirometry
pt’s at risk for post op pulm complications
significant hx of pulm disease, thoracic or abdomical surgery, obesity, long term smoker, elderly >70
normal FEV is 5, patient should be able to get __% of that which is
80, 4
high risk result for FEV
<2 L
high risk result for FEV/FVC
<0.5
normal FEV/FVC
80%
high risk VC in adult
<15cc/kg
high risk VC in child
<10cc/kg
why PFT pre-op
good to know pulm reserve so you can plan
bronchodilators are most important pre-op for patients with
> 15% improvement in FEV1 after treatment
normal I:E
1:2
severe emphysema requires longer
expiratory times 1:3
rapid correction in ETCO2 leads to
metabolic alkalosis.
the body handles acidosis or alkalosis better?
acidosis
with bronchospasm you should aviod
histamine releasing drugs
why does your patient become light when you treat with nebulized albuterol?
because it takes 10L of oxygen so youre diluting your gas
in terms of extubation, if FEV1 is ____ predicted, then extubation prob wont be effected
> 50%
if FEV is ___ predicted, only do life saving procedures under general
<25%
if FEV is between 25-50% with some hypoxemia and hypercarbia..
prolonged intubation probable
to extubate, RR should be less than
30
to extubate, ABG of 40% should show
PaO2 >70 and PACO2 <55
to extubate, MIF should be
more negative then -20
to extubate, vital capacity should be
> 15cckg
to intubate resp rate is
> 35
to intubate VC is
<15cc/kg in adult or <10cc/kg in child
intubate if mif is more negative than
20
intubate if PAO2 is
70 on fio2 of 40
intubate if A-a gradient is >
350 mmhg on 100% O2
intubate if PACO2 is
> 55
intubate if vd/vt is
> 0.6
intubate if clinically
airway burn, chemical burn, epiglottis, ams, rapidly deteriorating pulm status, fatigue
if youre worried about pneumothorax, get an X-ray on
exhalation
ABG must be measured within __ or what happens
15min , glycolysis will occur with lactic acid production, decreased pH and increased PCO2
ABG can be stored on ice for
1-2h
heparin may significantly lower PCO2 by
dilution, esp in children
buffer
substance that can absorb or donate H+
examples of buffers
bicarb (HCO3), hb, serum proteins, phosphate (HPO4)
normal ph
7.35-7.45
normal PCO2
35-45
normal PO2
75-105
normal bicarb
20-26
normal base excess
-3 to +3
blood gas machine assumes the person is breathing
Room air
an increase in PCO2 by 10mmhg causes a ____ in ph by ___
decrease 0.08
an decrease PCO2 by 10 will ___ ph by ___
increase 0.08
hypoxemia is PO2
75
A-a gradient measures
efficiency of lung, how well is oxygen making it from your lungs to your normal blood supply
normal a-a is approx
age/3
how does anesthesia affect A-a
widens
A-a is ___ with hypoventilation or low FiO2
normal
A-a is ____ with intrinsic lung disease - PTX,PE,Shunt, v/q mismatch, diffusion problems
widened
a decrease in bicarb by 10 ___ the pH by ___
decreases 0.15
bicarb and ph are ___ , PCO2 and ph are ___
direct, indirect
an increase in bicarb by 10 ___ the ph by
increases 0.15
** total body bicarb deficit =
base deficit x weight in kg x 0.4
usually replace ___ of total body bicarb deficit
half
resp acidosis caused by ____ventilation and ____carbia
hypoventilation , hyper
resp acidosis is ___ ph and ___ Paco2
low ph high PACO2
resp acidosis causes ___ FRC
decreased
resp acidosis causes
sleep apnea, obesity, trauma drugs CNS depression, upper or lower airway obstruction, asthma, pulm fibrosis
after __ days of resp acidosis, renal compensation occurs
1-2 days
how do the kidneys compensate for resp acidosis
H+ is excreted by the kidney and HCO3 is reabsorbed into blood to partially correct pH
resp alkalosis is __ph and __ paCO2
high, low
resp alkalosis is caused by ___ventilation and ___carbia
hyperventilation, hypocarbia
resp alka is caused by
hypoxic respiration (mtn climbing), CNS disease, encephalitis, anxiety, narcotic withdrawal, *pregnancy, artificial ventilation
how do the kidneys compensate for resp alkalosis
increased excretion of HCO3 and decreased secretion of H+ which partially corrects pH
meta acidosis is ___ph and ___HCO3
low low
causes of metabolic acidosis
lactic acidosis* from hypo perfusion, DKA,renal dz with bicarb loss (anion gap and k+), *diarrhea, ASA ingestion, high protein intake
metabolic acidosis compensation
resp compensation(central chemoreceptors) with hypocarbia, more rapid than renal compensation, partial correction
metabolic acidosis kidneys..
may increase H+ excretion
metabolic alkalosis ph and hco3
high ph and high hco3
causes of metabolic alkalosis
bicarb infusion,metabolism of lactate or citrate, loss of H+ from vomiting or excessive NGT suctioning
resp compensation for met alka
limited hypoventilation due to eventual hypoxic drive, partial correction (cant slow respirations down enough)
metabolic alka kidneys
may increase bicarb excretion in urine
FRC is
ERV +RV
what decreases FRC
obesity, full belly,pregnant, trendelenberg
what is the most important clinical tool in assessing the severity of airway obstructive disease
FEV-1second
FEV -1 second definition
after max inspiration, the volume of air that can be forcefully expelled in one second
whats a normal FEV-1
2-5L
FEV1/FVC
> 75%
FEV1/FVC can tell you
how severe their obstructive lung disease is
mild risk
60-75
moderate risk
45-60
severe risk
35-45
extreme risk
<35
FEF 25-75 is effort ____
independent
FEF 25-75 reflects
collapse of small airways, peripheral airways. sensitive indicator early airway obstruction
MVV orMBC
maximal breathing capacity- “will to live” test
MVV is effort ___
dependent , non-specific
extra obstruction decreases ___ flow
insp
insp obstruction decreases ___ flow
exp
the downward slope on pressure volume loop is
FEV1
