random RT30 questions Flashcards
Removing a patient from a ventilator to ventilate manually can lead to which of the following?
- Barotrauma
- Lung derecruitment
- Increased airway resistance
- Ventilator-acquired pneumonia
1, 2, 4
Removing a patient from the ventilator for manual ventilation can inadvertently cause barotrauma by using excessive pressure during ventilation (>40 cm H2O). Disconnecting a patient who is being ventilated with a high level of PEEP (15 to 25 cm H2O) can cause derecruitment of the lung. Disconnection of the ventilator can cause contamination of the patient’s airway, increasing the patient’s risk of developing ventilator-associated pneumonia.
If the patient is in severe distress the initial step in the management of patient-ventilator asynchrony is which of the following?
If the patient is in severe distress, the first step is to disconnect the patient from the ventilator and carefully ventilate the patient using a manual resuscitation bag.
An increased arterial-to-end-tidal partial pressure CO2 gradient can help identify which of the following?
Capnographic findings can provide a clue to the presence of a PE. A decrease in the end-tidal carbon dioxide (PetCO2) value compared with previous readings and a widening of the arterial-to-end-tidal partial pressure CO2 gradient (P[a-et]CO2) may suggest the presence of an embolus.
What ends inspiration in pressure support ventilation?
Each pressure support breath is flow cycled
At what pressure is pressure support not high enough to contribute significantly to ventilatory support but is sufficient to overcome the work imposed by the ventilator system?
When pressure support is reduced to about 5 cm H2O, the pressure level is not high enough to contribute significantly to ventilatory support. However, this level of support usually is sufficient to overcome the work imposed by the ventilator system (i.e., the resistance of the ET tube, trigger sensitivity, demand-flow capabilities, and the type of humidifier used).
Which mode of ventilation delivers the exact amount of pressure required to overcome the resistive load imposed by the ET tube for the flow measured at the time?
Automatic tube compensation
The closed loop mode used for weaning from mechanical ventilation is which of the following?
ASV (adaptive support ventilation) is a patient-centered method of closed loop mechanical ventilation that increases or decreases ventilatory support based on monitored patient parameters.
A postoperative patient, still under anesthesia, is being ventilated with VC-CMV with Automode. After 2 hours the patient is waking up and beginning to breathe spontaneously. The ventilator will respond by _____________________.
switching to the volume support mode.
If a postoperative patient is still recovering from the effects of anesthesia and the ventilator operator has selected volume-controlled continuous mandatory ventilation (VC-CMV) with Automode as the operating mode, all breaths are mandatory (time triggered, volume limited, and time cycled). If the patient begins to trigger breaths, the ventilator switches to VS (patient triggered, pressure limited, and flow cycled with a volume target) and remains in this mode as long as the patient is breathing spontaneously.
calculate anion gap
Na-Cl-HCO3
calculate VO2
QT(PaO2-PvO2)10
calculate Raw
PIP-Pplat
calculate Cs
Vte/Pplat-PEEP
calculate Cd
Vte/PIP-PEEP
QS/QT
A-a X .003/(A-a X .003) + (CaO2 - CVO2)
Calculate for Qs/Qt shunt
Step 1
PAO2
FiO2(Pb-47) - PaCO2 (FiO2+[1-FiO2/.8])
Calculate for Qs/Qt shunt
Step 2
(A-a).003
Calculate for Qs/Qt shunt
Step 3
C[a-v]O2
CaO2=(Pao2 X .003) + (SaO2 X 1.34 X Hb)
Cvo2=(PvO2 X .003) + (SvO2 X 1.34 X Hb)
Cuff pressures
20 to 25 mm Hg
27 to 34 cm H2O
Upper inflection point
Indicates a point at which large numbers of alveoli are becoming over-inflated
Inflection point
Occurs during deflation also sometimes called the deflection point and represents collapse of a significant number of lung units following full inflation of the lungs
Types of recruitment maneuvers
Sustained inflation PC CMV with a high peep level PC CMV with increased peep Recruitment and decremental peep Sigh techniques
APRV
P high
P low=0
T high
T low= .5 sec
Contraindications for peep
Hypovolemia: it must be treated first
Absolute contraindication untreated significant pneumothorax or a tension pneumothorax
Ve and IBW
Mulitply 3.5 (F) or 4 (M) to BSA equals Ve
f calculation
60 sec/ TCT sec
Ti calculation
Vt/ flow
Vt calculation
Flow X Ti
Flow calculation
Vt / Ti
Time constant calculation
C X Raw
One time constant
63%
Two time constants
86%
Three time constants
95%
Four time constants
98%
Five or more time constants
100%
Less than 3 time constants
May result in incomplete delivery of Vt
Inspiratory muscles
Scalene (anterior, medial, posterior)
Sternocleidomastoids
Pectorals ( major and minor)
Trapezius
Expiratory muscles
Rectus abdominus External oblique Internal oblique Transverse abdominal Serratus (anterior, posterior) Latissimus dorsi
MMV
Minimum minute ventilation aka aumented minute ventilation, is used primarily for weaning. It allows the operator to minimum Ve (70 - 90%) of the pts current Ve
MIP values
cm H2O
Normal -100 to -50
Critical -20 to 0
MEP values
cm H2O
Normal 100
Critical <40
Vital capacity VC values
mL/kg
Normal 65 to75
Critical <10 to 15
Tidal volume Vt values
mL/kg
Normal 6 to 8
Critical <6
