You Lab-Solutely need to know this
You are performing an Allen Test on your patient, when you find that their coloring returns in about 16 seconds. What does this indicate?
Negative test.
*Coloring in the hand should return in about 10 seconds; this suggests that collateral flow is inadequate.
A COPD patient presents with chronic ventilatory failure. What ABG pattern would you expect?
Elevated PaCO₂ (>45 mmHg), normal or slightly acidotic pH (~7.35–7.39), elevated HCO₃⁻ (renal compensation).
How is chronic ventilatory failure different from acute ventilatory failure on ABG analysis?
Chronic: elevated PaCO₂ with near-normal pH (renal compensation).
Acute: elevated PaCO₂ with low pH (uncompensated).
What is normal anatomic shunt?
2-5% of the Cardiac Output = 250 mL
What is a normal CaO2
19.8 mL/O2/100mL
What respiratory complication is associated with increased compliance?
Emphysema (destruction of elastic tissue)
A patient’s PaO₂ is 50 mmHg on FiO₂ 0.6. What is their PaO₂/FiO₂ ratio and what does it suggest?
PaO₂/FiO₂ = 50 / 0.6 ≈ 83 → indicates severe hypoxemia
What is the equation for PIO2?
PIO₂ = (PB – PH₂O) × FiO₂
List two clinical examples of V/Q mismatch
Pulmonary diseases COPD (causes low V/Q) Pneumonia Interstitial lung disease Pulmonary embolus (causes abnormally high V/Q) Atelectasis (extreme case of V/Q mismatching where there is perfusion without ventilation
Calculate CaO2.
Hb= 7
SaO2= 82
PaO2= 88
FiO2: 0.21
CaO₂ = (Hb × 1.34 × SaO₂) + (PaO₂ × 0.003)
(7*1.34*82) + (88*0.003)= 7.9 mL/dL
You have a patient who is suffering from pneumonia, and they also have chronic obstructive pulmonary disease. They are considered to be _____. Additionally, list one type of pneumonia they could have.
Acute on Chronic Respiratory Failure.
Streptococcus pneumoniae, Haemophilus influenzae, Klebsiella pneumoniae, legionella pneumophila, Chlamydophila (chlamydia) pneumoniae, mycoplasma pneumoniae, bordetella pertussis, mycobacterium tuberculosis
What is the interpretation of this ABG?
pH- 7.44, PaCO2- 24mm Hg, HCO3- 16mm Hg
Chronic alveolar hyperventilation (fully compensated respiratory alkalosis)
Indications for Mechanical Vent
apnea, AVF, impending vent failure, severe oxygenation problems (refractory hypoxemia)
Define a physiological shunt.
Venous blood bypasses oxygenation in alveoli and mixes with arterial blood, reducing PaO₂ and CaO₂.
What is a normal Hb for female?
F= 12-15.5 mL/dL
M= 13.5-17.5 mL/dL
-EGANS
You have a patient who is male with a normal HCT. (List a possible value they could fall in.) They have come into the hospital for a KFT, with microalbumin levels that are found to be 60 mg/g. The patient also received testing for BUN and creatinine levels. What findings can you gather from these results? (HINT: Tell me what 60mg/g tells you in terms of KFT, and do the BUN and creatinine tests help tell you anything about kidney disease?)
HCT Values for normal range in males: 40-50%. They have early-stage kidney disease. Tests that measure an elevated BUN and creatinine do not indicate early impairment.
Which HH equations are correct?
1. pH= 6.1 + log ([HCO3-]/ (PaCO2 * 0.03))
2. pH= pka +log ([A-]/[HA])
3. pH= pka +log ([HCO3-]/[H2CO3])
4. KA= [H+]x[HCO3]/[H2CO3]
5. 1= p^2 +2pq+q^2
1,3,4
What is the primary difference between oxygenation and ventilation?
Oxygenation = O₂ delivery to blood; ventilation = CO₂ removal
* PaO₂ and SaO₂ assess oxygenation; PaCO₂ reflects ventilation adequacy.
What are the normal electrolyte levels (name one value for each)
Na+: 136-145 mEq/L
K+: 3.5-5.1 mEq/L
Cl-: 98-107 mEq/L
HCO3-: 22-26 mEq/L
Most common causes of community acquired pneumonia?
Pneumocytis jirovecii
What are the criteria for extubating?
Cough/Gagging and the ability to manage secretions
VT > 5 ml/kg IBW
RSBI <105 breaths/min/L
Vital capacity (VC): > 10–15 mL/kg.
Minute ventilation (VE): < 10 L/min (with stable ABGs).
What is the purpose of IGRA testing?
Detect latent or active MTB infection without skin injection. Alternative testing TST. In vitro.
Decrease stroke volume and/or decreased heart rate
Ischemic heart disease
Myocardial infarction
Cardiac arrhythmia
Heart failure (CHF) (left ventricular failure)
Hypertension
Hypovolemia (blood or fluid loss)
Valvular disease
Cardiomyopathies
Late septic shock
Mechanical ventilatory support wit positive end-expiratory pressure (PEEP)
Na+: 137 mEq/L
K+: 4 mEq/L
Cl-: 100 mEq/L
HCO3-: 24 mEq/L
ANION GAP EQ
(Na+K)-(Cl-+HCO3-)
(137+4)-(100+24)
= 17 mEq/L
Tell me how you would take a sputum sample ideally from the patient. List the steps and what you DONT want to see in lab results.
Morning before eating/brushing teeth
Rinse mouth w/ plain water no mouthwash
Take deep breaths and cough hard from chest
Spit mucus not saliva into sterile cup
Close lid tightly and send to lab
Saline can help for patients ineffective cough
IF THERE IS SQUAMOUS CELLS… it is not sputum but saliva