Surg: Mechanical Vent Flashcards
what are pulmonary pressures referenced to?
atmospheric pressure: if alveolar pressure is equal to atmospheric then the pulm pressure is 0
Normal breathing is what type of environment? (relating to pressure)
negative pressure environment
Negative pressure ventilation: artificial airway needed? is it appropriate for diseased lungs? used primarily when?
- 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
positive pressure ventilation: artificial airway needed? is it appropriate for diseased lungs? what pulmonary flows can it measure?
- most cases, artificial airway needed (NIV)
- can ventilate diseased lungs
- control of I:E ratios, flow, flow pattern, cycling mechanism
5 indications for mechanical ventilation (maybe)
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
what is the goal of mechanical ventilation? (KNOW)
provide O2 and remove CO2
what 2 lung characteristics do MV’s help overcome?
1) . compliance
2) . resistance
what is lung compliance? what is it related to?
“stiffness” of the lungs
related to volume
what is lung resistance? what is this related to?
pressure difference (airway diameter) related to flow
which two MV settings tell you about oxygenation?
PEEP, FiO2
which two MV settings tell you about ventilation?
RR, Tidal volume
what are the 6 indications for intubation?
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
what is oxygen toxicity?
FiO2 >60% for exposure times > or = to 24 hours
what is the rule of thumb for preventing oxygen toxicity?
use the lowest FiO2 to obtain a satisfactory PaO2/SaO2
Pathophys of oxygen toxicity (4 phases)
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
two damaging results of oxygen toxicity
- damaged alveolar/capillary membranes
- edema, proteins, other debris flood the air spaces (surfactant probs, PHTN, V/Q mismatch, etc)
what is the purpose of low tidal volume ventilation?
its a protective measure to prevent over distention of alveoli by limiting airway pressures (uses PEEP)
what disease is low tidal volume ventilation used for? how does it help this disease?
ARDS (reduces mortality and higher rate of ventilator free days)
what is ARDS?
An acute and diffuse inflammatory response within the lungs that results in pulmonary edema and respiratory failure
3 inclusion criteria of ARDS?
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
how do you manage ARDS? (4)
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
