Surg: Mechanical Vent

Question 1

what are pulmonary pressures referenced to?

Answer 1

atmospheric pressure: if alveolar pressure is equal to atmospheric then the pulm pressure is 0

Question 2

Normal breathing is what type of environment? (relating to pressure)

Answer 2

negative pressure environment

Question 3

Negative pressure ventilation: artificial airway needed? is it appropriate for diseased lungs? used primarily when?

Answer 3

• no artificial airway needed
• not adequate for diseased lungs
• used primarily in home care for intermittent vent support for ppl with NORMAL LUNGS but neuromuscular disease

Question 4

positive pressure ventilation: artificial airway needed? is it appropriate for diseased lungs? what pulmonary flows can it measure?

Answer 4

• most cases, artificial airway needed (NIV)
• can ventilate diseased lungs
• control of I:E ratios, flow, flow pattern, cycling mechanism

Question 5

5 indications for mechanical ventilation (maybe)

Answer 5

1) . apnea
2) . acute ventilatory failure
3) . impending ventilatory failure
4) . severe oxygenation defect
5) . refractory hypoxic respiratory failure with increased work of breathing or an ineffective breathing pattern

Question 6

what is the goal of mechanical ventilation? (KNOW)

Answer 6

provide O2 and remove CO2

Question 7

what 2 lung characteristics do MV’s help overcome?

Answer 7

1) . compliance

2) . resistance

Question 8

what is lung compliance? what is it related to?

Answer 8

“stiffness” of the lungs

related to volume

Question 9

what is lung resistance? what is this related to?

Answer 9

pressure difference (airway diameter)
related to flow

Question 10

which two MV settings tell you about oxygenation?

Answer 10

PEEP, FiO2

Question 11

which two MV settings tell you about ventilation?

Answer 11

RR, Tidal volume

Question 12

what are the 6 indications for intubation?

Answer 12

1) . respiratory failure due to inadequate oxygenation and/or vent
2) . bypass upper airway obstruction
3) . inability to maintain patent airway due to other factors (dec level of consciousness)
4) . aid clearance of secretions
5) . reduce risk of large volume aspiration
6) . apply positive pressure ventilation

Question 13

what is oxygen toxicity?

Answer 13

FiO2 >60% for exposure times > or = to 24 hours

Question 14

what is the rule of thumb for preventing oxygen toxicity?

Answer 14

use the lowest FiO2 to obtain a satisfactory PaO2/SaO2

Question 15

Pathophys of oxygen toxicity (4 phases)

Answer 15

1) . initiation- increase in ROS and lungs fail to clear mucous
2) . inflammation- destruction of ACM and migration of inflam mediators
3) . proliferation- cellular hypertrophy, increased secretions, and inc monocytes
4) . fibrosis- irreversible thickening of interstitium

Question 16

two damaging results of oxygen toxicity

Answer 16

• damaged alveolar/capillary membranes

- edema, proteins, other debris flood the air spaces (surfactant probs, PHTN, V/Q mismatch, etc)

Question 17

what is the purpose of low tidal volume ventilation?

Answer 17

its a protective measure to prevent over distention of alveoli by limiting airway pressures (uses PEEP)

Question 18

what disease is low tidal volume ventilation used for? how does it help this disease?

Answer 18

ARDS (reduces mortality and higher rate of ventilator free days)

Question 19

what is ARDS?

Answer 19

An acute and diffuse inflammatory response within the lungs that results in pulmonary edema and respiratory failure

Question 20

3 inclusion criteria of ARDS?

Answer 20

1) . PaO2/FiO2 ≤ 300
2) . Acute onset (within 7 days of some defined event)
3) . Bilateral (patchy, diffuse, or homogenous) infiltrates consistent with pulmonary edema

Question 21

how do you manage ARDS? (4)

Answer 21

1) . supportive care- MV with low tidal volumes and inspiratory pressure (4-6 ml/kg to maintain pressures less than 30 cmH2O)
2) . prone position >12 hr/day
3) . NO HFOV
4) . Should use higher PEEP