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MV - Exam #3
Mechanical Ventilation Exam 3
| Question | Answer |
|---|---|
| What is a trigger? | Signals ventilator to begin inspiration; how breath is started |
| What is a cycle? | Parameters on the vent that terminate inspiration; how the vent ends the breath |
| What are the different triggers that can be set on the vent? | Time, Pressure, Flow |
| What is time triggered ventilation? | Inspiration initiated when a preset time interval has been reach; controlled RR, only machine breaths |
| What is pressure triggered ventilation? | Inspiration initiated when ventilator senses patient's spontaneous inspiratory efforts; controlled by pressure sensitivity |
| What is the normal sensitivity setting? | -1 to -5 cmH2O (-2 is ideal) |
| How does increasing the sensitivity number effect the sensitivity of the vent? | Higher the number (-5), less sensitive the setting; harder to initiate a breath, more the patient has to pull back |
| How does lowering the sensitivity number effect the sensitivity of the vent? | Lower the number (-1), more sensitive the setting; easier to initiate a breath, less patient has to pull back |
| What should be done if the patient is having difficulty triggering a breath on the vent? | Decrease sensitivity # (this makes the vent MORE sensitive) |
| What is flow triggered ventilation? | Low amount of continuous air flows through circuit, as patient tries to initiate a breath, amount of flow at patient wye changes triggering inspiration, controlled by flow (sensitivity) - more flow = easier to inspire, ONLY patient breaths |
| What are the different ways a ventilator can be cycled? | Volume, Time, Pressure, Flow, HPL, HVL |
| What is volume cycled ventilation? | Inspiration ends when preset VT is reached; volume is constant, PIP is variable |
| What is the advantage of volume cycled ventilation? | Guaranteed VT |
| What is the disadvantage of volume cycled ventilation? | PIP may increase too high (causing barotrauma) - PIP must be monitored closely |
| What is time cycled ventilation? | Inspiration ends when preset inspiratory time has been met; volume is variable |
| What is the advantage of time cycled ventilation? | Best method to control I:E ratio |
| What is the disadvantage of time cycled ventilation? | VT dependent on lung cL and RAW (atelectasis), very important to monitor exhaled VT |
| When does the breath end in PCV? | When time has been met, not pressure |
| What is pressure cycled ventilation? | Inspiration ends when preset PIP is reached; volume is variable (varies directly with lung cL and indirectly with RAW); flow and pressure are constant |
| What is the advantage of pressure cycled ventilation? | PIP (and MAP) is controlled (reduces barotrauma) |
| What is the optimal PIP in pressure cycled ventilation? | < 50 cmH2O |
| What is the optimal MAP in pressure cycled ventilation? | < 30 cmH2O |
| What is the disadvantage of pressure cycled ventilation? | Decreased cL and increased RAW = lower VT (can build up CO2; atelectasis) - need to monitor exhaled VT (MOST important to monitor!) |
| What is high pressure limit (HPL or HVL) cycled ventilation? | Safety measure (alarm setting), ends inspiration when high pressure limit value is reached, even if full VT is not delivered. Used with volume ventilation to protect against barotrauma |
| Which waveform mimic spontaneous breathing? | Sine (Sinusoidal) - flow starts slow, goes to peak flow, then slowly back down |
| What is normal MawP? | <10 cmH2O (<30 cmH2O) |
| What is critical MawP? | >30 cmH2O |
| What is TCT? | Total Cycle Time - total time it takes for both inhalation and exhalation to occur |
| How is TCT calculated? | 60/RR |
| How is inspiratory time calculated? | TCT/I+E |
| How is expiratory time calculated? | TCT - I time |
| What is I time %? | Percentage of total breath that is allowed for inspiration |
| How is I time % calculated? | I / I+E |
| What is inspiratory flow? | Speed of the gas flowing in during inspiration |
| How is inspiratory flow rate calculated? | Set MV / I time% |
| What is barotrauma? | Trauma caused by high pressure |
| What is volutrauma? | Trauma caused by high volumes of gas |
| What are the benefits of CPAP? | Increased FRC, decreased pressure need for alveolar inflation, decreased WOB, less FiO2 to achieve adequate PaO2, most therapeutic for hypoxemia secondary to intrapulmonary shunting, increased cL, stabilizes alveoli |
| What is PEEP? | Positive End Expiratory Pressure, preset pressure present in airways at end expiration, can be used in ANY mode of ventilation |
| How does PEEP improve gas exchange? | Preventing alveolar collapse, recruiting more lung units (alveoli), increasing FRC, redistributing fluid in alveoli, improving lung compliance |
| What are the indications for PEEP? | Hypoxemia, mechanical ventilation, severe restrictive lung disease, flail chest (ALWAYS) |
| What are the contraindications for PEEP? | Increased ICPs, untreated pneumothorax, brocho-pleural fistula |
| What is VC-CMV? | Volume Control-Controlled Mandatory Ventilation - set RR, set VT, PIP is variable, time triggered, volume and HPL cycled, machine breaths ONLY, patient cannot breath over vent |
| What is PC-CMV? | Pressure Control-Controlled Mandatory Ventilation-Set RR, set PIP, set I time, VT is variable, time triggered, time and HVL cycled, machine breaths only, patient cannot breathe over vent |
| What is VC-AC? | Volume Control-Assist Control-set RR, set VT, PIP is variable, time, pressure, and flow triggered, volume and flow cycled, machine and assisted breaths, patient can breathe between machine breaths, VT is constant |
| What is PC-AC? | Pressure Control-Assist Control-set RR, set PIP, set I time, VT is variable, time, pressure, and flow triggered, time and HVL cycled, machine and assisted breaths, patient can breathe between machine breaths, PIP is constant |
| What is VC-SIMV? | Volume Control-Synchronized Intermittent Mandatory Ventilation- Set RR, set VT, PIP is variable, time, pressure, and flow triggered, volume, HPL, and flow cycled, machine and spontaneous breaths, patient can breathe between machine breaths, VT varies |
| What is PC-SIMV? | Pressure Control-Synchronized Intermittent Mandatory Ventilation-set RR, set PIP, set I time, time, pressure, and flow triggered, time, HVL, and flow cycled, machine and spontaneous breaths, patient can breathe between machine breaths, PIP varies |
| What is APRV? | Airway Pressure Release Ventilation-aka Bilevel or Biphasic Ventilation: has set RR, but VT is not set, patient can initiate breaths between machine breaths during either high or low pressure |
| What are the two pressures of APRV? | High PEEP and low PEEP, high pressure maintained majority of time, low pressure maintained for very short intervals - allows for exhalation and gas exchange, recruit alveoli to improve oxygenation and FRC |
| What are the disadvantages of APRV? | Variable VT, RCP must closely monitor MV and ABGs for CO2 changes |
| How can you confirm correct placement of ET tube? | CXR, breath sounds, chest rise, CO2 detector (EZ cap or in line) |
| What are the indications for trach placement? | Long term ventilation (>14 days), upper airway/facial trauma, sleep apnea |
| What is pressure support ventilation? | No set RR or VT, pressure and flow triggers, flow cycled, spontaneous breaths only, can be used as a stand alone mode or added to other spontaneous breath modes, set pressure delivered and held through inspiration |
| Define I:E ratio | Portion of inspiratory time compared to portion of expiratory time |
| What are the different drive mechanisms? | Piston (Rotary and Linear), Reducing Valve, Bellows, Microprocessor-controlled pneumatics |
| What is Fluidics? How does it work? | Gas flow and pressure controlled without moving parts; uses flow splitters to direct flow of gas |
| What is sensitivity? | Amount of negative pressure that must be generated to begin inspiration; determines how easy or difficult it is for patient to initiate inspiration, only for when patient initiates breath in between machine breaths (or all breaths of CPAP) |
| What are machine breaths? | Breaths triggered and ended by machine (any set breath) |
| What are assisted breaths? | Breaths triggered by the patient and ended by the machine |
| What are spontaneous breaths? | Breaths triggered and ended by the patient |
| What cuff pressure occludes lymphatic flow? | >5 mmHg |
| What cuff pressure occludes venous flow? | >18 mmHg |
| What cuff pressure occludes arterial flow? | >30 mmHg |
| What is an OPA? | Oropharyngeal airway-holds tongue away from posterior wall of the pharynx, only used on unconscious patient, measure from tip of ear to corner of mouth for correct size |
| What are the two types of OPAs? | Guedell (tubular with hole in the middle) and Berman (channels on the side - I beam) |
| What is an NPA? | Nasopharyngeal airway (aka nasal trumpet), holds tongues away from posterior wall of the pharynx, best tolerated by conscious patients, measure from tip of ear to tip of nose |
| What is an ETT? | Endotracheal tube, tube inserted into trachea via nose or mouth, can be cuffed or uncuffed (kids) |
| What are the indications for ETT? | Facilitate suctioning, protect lower airway, bypass upper airway obstruction, facilitate mechanical ventilation, administration of drugs |
| What are the possible complications or hazards of ETT? | Infection, tracheoesophageal fistula, loss of communication, cuff rupture, cuff herniation |
| What are the different types of laryngoscopes? | Miller (straight - lifts directly), Macintosh (curved - lift indirectly |
| What is normal PaO2? | 80 - 100 mmHg |
| What is the range for mild hypoxemia? | 60 - 79 mmHg |
| What is the range for moderate hypoxemia? | 40 - 59 mmHg |
| What is the range for severe hypoxemia? | <40 mmHg |
| What are the indications for pressure support ventilation? | Decreased spontaneous VT (<5 mL/kg of IBW), increased RR (>25-30), increased WOB (accessory muscle use, fatigue, increased vitals, diaphoresis, decreased SpO2) |
Created by:
ashconrad417
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