Mechanical Ventilation Flashcards
ventilation
movement of gas in and out of the alveoli
ventilate is defined by
PaCO2
normal 35-45 mmHg
oxygenation is defined by
PaO2 or SpO2
T/F whe breathing 100% O2 oxygenation cannot be improved by more ventilation
True
apneic oxygenation is possible - ventilation may not be needed for oxygenation
T/F using 100% oxygen can insure good oxygenation in most circumstances
resistance limits
flow
resistance = pressure difference / flow
compliance limits
Volume
complience = volume / flow
what is mechanical ventilation
method of artificial ventilation where mechanical means is used to assust or replace spontaneous breathing
provided by ventilator or person
types of ventilation
spontaneous
assisted
mandatory (or controlled)
IPPV
intermittent positive pressure ventilation
positive pressure is maintained only during inspiration
IMV
intermittent mandatory ventilation
operator sets a predetermined number of positive breaths but patient can also breathe freely inbetween
CPAP
continuous positive airway pressure
spontaneous breathing with positive pressure durinng inspiration and expiration
PIP
peak inspiratory pressure
inflates the alveoli, opens atelectasis or causes barotrauma
PEEP
positive end expiratory pressure
keeps alveoli open (prevents re-collapse)
T/F the benefit of PEEP is questionable durinf routine anesthesia
True
indications for PEEP
open thorax
lung parenchymal disease
following alveolar recruitment maneuver
indications for mechanical ventilation under anesthesia
want to decrease PaCO2 (intubated patients on 100% O2)
breathing air: hypoemia
specific indications for MV under anesthesia
neuromuscular blockade
thoracic surgery
control of intracranial pressure
chest wall or diaphragmatic trauma
side effects of MV
impairs venous return and cardiac output
may cause hypotension
direct effects of hypercapnia
peripheral vasodilation
decreased myocardial contractility
increased intracranial pressure
indirect effects of hypercapnia
via catecholamine release
tachycardia
increased myocardial contractility
T/F ventilating during anesthesia is a debated issue (esp. in horses)
True
permissive hypercapnia may be acceptable up to
60-70 mmHg for the purpose to improve circulation
tidal volume in healthy lungs
10-15 ml/kg
respiratory rate for ventilating healthy lungs
10-15 breaths/min
inspiratory time (healthy lungs)
1-2 sec
tidal volume in sick lungs is bigger/smaller
smaller
2 respiratory assist devices
ambu bag
demand valve
modes of MV
volume controlled ventillation mode
pressure controlled ventilation mode
common source of driving power
pneumatically driven
uses pressurized gas source
control variables
flow controlled
pressure controlled
ventilator controls these variables
u
cycle variables
defines the start of expiration
volume, pressure, and time cycled
trigger variable
defines start of inspriation - inspiration starts when a set value is reached
pressure and flow trigger
limit variable
stops inspiration
volume and pressure limit
T/F in an atelectic lung, increasing alveolar minute ventilation can remove more CO2 but without opening the atelectasis you will not be able to improve oxygenation
True
