Thoracics

Question 1

formula for pulmonary vascular resistance

Answer 1

PVR = [(meanPAP- wedge pressure)/CO] x 80

normal PVR = 50-150 dyne-sec/cm2

Question 2

During apnea, the PaCO2 will increase by ___ mmHg during the first minute and then ___ mmHg each minute thereafter

Answer 2

PaCO2 will increase 6 mmHg in the first minute of apnea PaCO2 will increase 3-4 mmHg in each subsequent minute

Question 3

O2 requirements (in mL/kg/min) for an adult

Answer 3

3-4 mL/kg/min ~250 mL/min for 70 kg pt

Question 4

O2 requirements (in mL/kg/min) for a neonate

Answer 4

7-9 mL/kg/min

Question 5

formula for total O2 content of blood

Answer 5

O2 content = 1.34 x Hg x arterial saturation + (o.oo3 x PaO2) * Hg in g/dL * SpO2 as a fraction of 1 each ram of Hg can carry 1.34 mL of O2 when fully saturated

Question 6

Absolute Indications for one-lung ventilation

Answer 6

Protective isolation

• Massive hemorrhage
• Infection

Control of ventilation distribution

• Bronchopleural or bronchopleural cutaneous fistula
• Giant cyst or bullae (risk of rupture w PPV)
• Major bronchial disruption or trauma

Unilateral lung lavage

VATS

Question 7

Relative indications for OLV

Answer 7

surgical exposure

• Thoracic aortic surgery
• upper lobectomy
• pneumonectomy
• esophageal surgery
• minimally invasive cardiac surgery (MV repair)

Question 8

Type 1 pneumocytes

Answer 8

responsible for gas exchange

Question 9

Type 2 pneumocytes

Answer 9

make surfactant

Question 10

During direct laryngoscopy, FLEXION of the cervical spine is maximal at which level? [2012]

Answer 10

the sniffing position:

• near full extension @ O-A complex
• 25-35 degree flexion: C2-C4
• spine relatively straight belowe C 5

Question 11

6. Which of the following is LEAST effort dependent? [2012]
   a) FEV
   b) FVC
   c) FEF 25-75
   d) Flow volume loop

Answer 11

FEF 25 - 75

• average forced expiratory flow during the middle half of the FEV maneuver
• Decreased flow rates from this middle 50% of FVC are indicative of obstructive disease of medium sized areas
• This test is farly sensitive in the early stages of obstructive airway disease
• Decreased FEV 25-75 frequently will be observed before other obstructive manifestations occur. “Although somewhat effect dependent, the test is much more reliable and reproducible than FEV1/FVC”

Question 12

First site of gas exchange encounter in the lungs? [2012]

Answer 12

Respiratory bronchioles

Question 13

The alveolar-to-deadspace ventilation ratio is ____ during spontaneous ventilation and ___ during PPV

Answer 13

spontaneous: 2:1

PPV: 1:1

Barash pg 361

Question 14

anatomic deadspace = ____ ml/kg of lean body weight

Answer 14

2

Question 15

Massive hemoptysis =

Answer 15

greater than 200mL of blood in 24 - 48 hr

Question 16

Risk factors for desat during OLV

Answer 16

Miller Ch 53, Box 53.7

1. High percentage of ventilatio or perfusion to the operative lung on VQ scan
2. Poor PaO2 during two-lung ventilation, particularily in the lateral position intraoperatively
3. Right-sided thoracotomy
4. Normal preoperative spirometry (FEV1 or FVC) or restrictive lung disease
5. supine position during OLV