What are the ABG normal values?
pH = 7.4 Bicarb - 24 CO2 - 40 PO2 - 75-100 Base excess = -3 to 3
What pH is considered acidemic?
What pH is considered alkalotic?
How can you tell if the alteration in pH is respiratory?
CO2 will be the most affected in a resp problem
How can you tell is the pH alteration is metabolic?
HCO3 will be the most affected in a metabolic problem
An increase or decrease in PCO2 by _________mm Hg causes a a decrease or increase in pH by _______.
10mmHg and pH 0.08
What is the A-a gradient?
It is a measure of lung efficiency
What is the equation for PAO2?
How do you find the A-a gradient?
PAO2 = (PB * PH2O) (FIO2) - PaCO2/0.8)
PB = 760, PH2O = 47
To find A-a gradient, subtract PAO2 from PaO2 measured on ABG
What is a rough estimate of a NORMAL A-a gradient?
approximately your age/3
or less than 20mmHg difference
What would cause a widened A-a gradient?
pneumothorax, PE, shunt, VQ mismatch, diffusion problems
How would you treat an abnormal A-a gradient?
tx underlying cause - supplemental O2, adjust ventilation, tx atelectasis, add PEEP,
An increase or decrease in bicarb by _________mmoles will increase or decrease the pH by __________.
10 mmoles, pH 0.15
What is the equation for TOTAL BODY bicarb deficit?
base deficit x wt in kg x 0.4 = answer is in mEq/L
How much of the total body bicarb deficit would you replace?
half of the deficit
What is an acute cause of low pH and high PCO2?
hypoventilation with hypercarbia
What is a chronic cause of low pH and high PCO2? (resp acidosis)
How long does it take the kidneys to help compensate the pH in acidosis?
________ ions are excreted by the kidneys and _________ is reabsorbed into blood to PARTIALLY correct the pH
What can cause a HIGH pH and LOW PaCO2? (resp alkalosis)
Hyperventilation with hypocarbia
What are some causes of resp alkalosis?
Pregnancy, artificial ventilation, hypoxic resp, CNS dzs, encephalitis, anxiety, withdrawal, early septic shock
What are some causes of LOW pH and LOW HCO3? (met acidosis)
Lactic acidosis, Diarrhea, ASA ingestion, high protein intake, DKA,
What are some causes of HIGH pH and HIGH HCO3? (met alkalosis)
Loss of H+ from vomiting or excessive NG tube suctioning
What is the most important clinical tool in assessing the severity of airway disease?
What is FEV-1? What are the normal values?
After max inspiration, the volume of air that can be forcefully exhaled in 1 second Normal - 3-5 liters
How else can FEV-1 be reported?
Can also be reported as a percent of FVC. FEV-1/FVC
What is a normal FEV1/FVC?
What is a moderate and extreme FEV1/FVC and what would it indicate?
Mod = 45-60% Extreme = < 35% Degree of risk of obstructive lung disease
what is FEF 25-75 and how is it different from FEV1?
Reflects collapse of small/peripheral airways and It is a sensitive indicator of early airway obstruction. It is different because it is effort independent
What is the nickname for Maximal Voluntary Ventilation (MVV) or Maximal Breathing Capacity (MBC)?
the "will to live" test - it is the maximal amount of air a pt can exhale in one minute at maximal effort (hyperventilation) tests motivation, mechanics, strength and endurance
What patient are at risk for post-op pulmonary complications?
-Hx of pulmonary disease -Thoracic/abdominal(upper) surgery -Obesity -Long-term smoker -Elderly patients (>70 yrs)
Why get a pulmonary functioning Test preoperative?
Have a better plan and predict pre-, inta-, and post-operative pulmonary care requirements.
What is the normal inspiration:expiratory (I:E)?
What is the inspiration:expiratory (I:E) of a COPD patient?
T/F: CO2 retainers: EtCO2 should be keep near the patient's baseline, a rapid correction will lead to metabolic alkalosis.
What class of drugs should be avoided during bronchospasm?
Histamine releasing drugs
What drugs release histamine?
-Pentothal (STP) -Morphine (MSO4) -Atracurium -Mivacurium -Neostigmine
The extubation criteria are:
- VSS, awake and alert, resp. rate<30
- ABG on FIO2 40% --> PaO2>70 and PaCO2<55
- MIF is more negative than -20cm H2O
- VC > 15cc/kg
Mechanic intubation criteria are:
RR>35, VC <10cc/Kg in child or 15cc/kg adult, MIF more neg. than -20cmH2O
Oxygenation intubation criteria are:
PaO2 < 70mmHg on FiO2 of 40%, A-a gradient > 350mmHg on 100% O2
Ventilation intubation criteria are:
PaCO2 > 55 (except in chronic hypercarbia), Vd/Vt > 0.6 (remember normal dead space is 30%)
Clinical intubation criteria are:
airway burn, chemical burn, epiglottis, mental status change, rapidly deteriorating pulmonary status, fatigue
An arterial blood gas must be measured within 15 minutes or ________ will occur.
glycolysis (The sample can be placed on ice for 1 to 2 hours)
What MAY heparin due to a small arterial blood gas sample?
What results would indicate high risk PFT's on FEV1 and FEV1/FVC?
FEV1 <2 liter/second