3-2: Mechanical Ventilation Flashcards
What is the total lung capacity and typical range?
the volume of air the lungs can hold after max inhalation
5,500 - 6,000 mL
What is the tidal volume and typical range?
volume moved with each breath
~7 mL
What is exhaled tidal volume (Vte)
volume of air returned from a vented patient
What is the vital capacity (VC)? What is typical range?
the amount of air forced out of the lungs after a maximal respiration.
Average: 4.6-4.8
What is residual volume (RV) and normal range?
volume of air remaining in the lungs after maximal expiration
usually about 1 L in adult pts
Functional Residual Capacity = WHAT?
OXYGENATION
If you increase the FRC, you increase oxygenation
FRC is the volume of air remaining in the lungs at the end of a standard expiration
Minute ventilation = WHAT? define
CO2- capnography
the amount of air expired per minute
What is the difference between anatomical and physiological dead space.
anatomical dead space is just the air that remains in the conductive region. physiological dead space is all of anatomical + alveolar dead space. It is air that doesn’t participate in gas exchange
What are the indications for mechanical ventilation?
- acute respiratory failure
- hypovolemia despite maximum oxygen delivery
- apnea
- to increase lung volume (FRC)
- diffusion disturbances across alveolar/capillary membrane
- control PaCO2 in pts with head injuries
- to decrease the myocardial oxygen demand in the presence of acute coronary syndrome or PE
- when procedures require heavy sedation
- to facilitate alveolar recruitment and prevent atelectasis
What are the clinical indicators for mechanical ventilation?
- PaCO2 > 50 or pH <7.3
- PaO2 <60 with inspired O2 concentration >60%
- RR > 30-35
- decreased LOC with inability to protect airway
What are the goals of mechanical ventilation?
- maintain adequate PaO2 and PaCO2
- return ABG to normal for pt
- improve ventilation to meet demands
- decrease work of breathing
What measurement is important to keep an eye on when using a volume support ventilator?
Plateau pressure
Is CPAP a true mode of ventilation and why?
CPAP is not a true mode of ventilation because it does not provide additional pressure during inspiration
Is BIPAP a true mode of ventilation and why?
BIPAP is a true mode of ventilation because it provides inspiratory support
Why is CPAP used for treatment of acute COPD and CHF exacerbations?
These patients can’t get air OUT, and CPAP helps by keeping the diameter of the bronchi wider, allowing air flow out
What is iPAP?
inspiration PAP - similar to pressure support ventilation
it is ventilation, ETCO2
it is the SIZE of the breath
What is ePAP?
expiration PAP - provides pressure to maintain open airways during exhalation, enhancing oxygenation
it is oxygenation, SPO2
it is FRC- oxygenation
What is the range for PS-ventilation for iPAP in BIPAP?
5-20 cmH2O
adjust by 5
What is the range for PEEP for ePAP in BIPAP?
2-20 cmH2O
adjust by 2.5-5
In what conditions might you see “stiff lungs” or high plateau pressures?
- ARDS
- Pneumonia
- Pulmonary fibrosis
What is the difference between AC and SIMV
in AC, the patient receives the full volume or pressure that is set when they take a breath.
In SIMV, the patient takes what they can take and the volume of that breath is dependent on pt effort
What types of patients is IRV (inverse ratio ventilation) really good for and REALLY bad for?
really good: pneumonia and ARDS
really bad: asthma/COPD
What does an FiO2 of 0.4 mean?
40% inspired oxygen
What is the typical tidal volume for adults?
5-8 mL/kg
What is the typical I:E ratio?
1:1.5-2
Inverse I:E can’t be done in patients with a pH of < ____
7.2
What is the PIP?
Peak inspiratory pressure
sets the highest pressure that will be delivered in the vent circuit
What is the plateau pressure (P Plat)?
the overall pressure it took to overcome the elastic forces resisting inflation of the lungs during the static phase of inhalation
What is the goal P Plat
< 30
What is sigh?
an uncommon method used to help prevent atelectasis
volume of air that is 1.5-2x the inspired tidal volume
frequency about 6-10 times per hour
What is Paw
the current airway pressure
What is the equation for oxygen tank life?
lpm
What is the most common dysrhythmia as a complication of mechanical ventilation?
PVCs
What are the causes of atelectasis in vented patients?
- inadequate tidal volumes
- infrequent repositioning
- secretion retention
- high concentrations of oxygen (absorptive atelectasis)
What are the classic signs and symptoms of oxygen toxicity in a vented patient?
- V/Q mismatch
- diffuse pulmonary infiltrates on x-ray
- o2 saturations falling despite increases in FiO2
What are the early signs of oxygen toxicity in a vented patient?
substernal discomfort, malaise, fatigue, nausea
What are the late signs of oxygen toxicity in a vented patient?
decrease in lung compliance, decreased vital capacity, and increased PIPs
How can we prevent O2 toxicity in a vented pt?
decrease FiO2 as early as possible without causing hypoxemia
the goal is to wean the pt from 1.0 FiO2 to 0.5 FiO2 within the first 24 hours
What is the diagnostic triad for ventilator acquired pneumonia?
- pulmonary infection signs (purulent secretions, fever, and leukocytosis)
- bacteriologic evidence of pulmonary infection
- radiologic suggestions of pulmonary infection
