Critical Care

Question 1

When to manual bag mask?

Answer 1

Apnea, inadequate TV, excessive WOB, hypoxemia with poor ventilation, hypoventilation with hypercarbia

Question 2

How much can you deliver with bag mask?

Answer 2

Compress 8-10 RR, 1-1.5 L/bag, so up to 15L minute ventilation

Question 3

Consequences of excess bag masking?

Answer 3

Respiratory alkalosis, insufflating stomach, barotraum

Question 4

What are the indications for ETT?

Answer 4

1. AW protection
2. Relief of obstruction
3. Need mechanical ventilation to improve oxygenation (remember PAO2 variable include PaCO2)
4. Respiratory failure: apnea, inadequate TV, hypoxemia with poor ventilation
5. Shock
6. Hypoventilation with hypercarbia
7. Increased WOB
8. Need to facilitate pulmonary toilet - clear secretions

Question 5

What factors determine a difficult AW?

Answer 5

Neck mobility (cervical spine injury or short neck), external face, mouth opening, tongue size and oropharynx, jaw-thyromental distance

Question 6

What do you do when you anticipate a difficult AW?

Answer 6

Call for help, get flexible fiberoptic technique involved, Awake intubation (laryngoscopy), Layngeal Mask Airway (LMA); if that fails surgical airway

Question 7

Definition of hypoxemic respiratory failure?

Answer 7

1. ) PaO2 < 50-60 mm Hg on RA

2. ) P:F ratio < 300

Question 8

Definition of hypercapnic respiratory failure?

Answer 8

PaCO2 > 50 mm Hg WITH pH < 7.36

Question 9

What describes mixed respiratory failure?

Answer 9

Hypoxemia (ie Aa gradient) and hypercarbia

Question 10

What causes increased dead space?

Answer 10

Hypovolemia, low CO, PE, high airway pressures (resistance to flow)

Question 11

How can hypoventilation contribute to hypoxemia?

Answer 11

The resulting hypercarbia decreases the alveolar concentration of O2 (PAO2) due to the alveolar gas equation: PAO2 = FiO2 (Patm-P H2O) - PaCO2/R

Question 12

What are the advantages of BiPAP?

Answer 12

Avoids intubation, preserves airway reflexes, improves pt comfort, decreases need for sedation, shortens LOS, improves survival

Question 13

What are the advantages of BiPAP?

Answer 13

Avoids intubation, preserves airway reflexes, improves pt comfort, decreases need for sedation, shortens

Question 14

What determines I:E ratio? Consequences when it’s too big?

Answer 14

Inspiratory time: increased with more tidal volume and decreased rate

More inspiration than expiration means incomplete exhalation and breath stacking or auto-PEEP

Question 15

What is auto-PEEP and why is it bad? How do you decrease it?

Answer 15

Leads to increase mean airway pressures which can decrease venous return leading to HoTN and poor oxygenation

Decrease TV or RR or increase the gas flow rate to maximize expiratory time

Question 16

What determines mean airway pressures (PIP, Pplat)?

Answer 16

TV, I:E ratio (ideally 1:2), PEEP, inspiratory gas flow rate, auto-PEEP