Question 1

A 68-year-old female admitted for congestive heart failure is in respiratory distress and is being seen by the hospital's medical emergency team in her regular room.The patient is in obvious respiratory distress and is immediately placed on a nonrebreathing mask.Physical assessment reveals: pulse 138 and thready;respiratory rate 30,shallow and labored;temperature 37° C;blood pressure 110/68.Breath sounds are bilaterally decreased with coarse crackles on inspiration.EKG shows normal sinus rhythm with widened cardiac output (QT)interval and an occasional irregular beat.No coughing is noted.The arterial blood gas on the nonrebreathing mask is: pH 7.34;PCO₂ 46 mm Hg;partial pressure of oxygen in the arteries (PO₂)is 52 mm Hg;oxygen saturation is 86%;bicarbonate (HCO₃^-)is 24 mEq/L.The patient is diaphoretic.The most appropriate ventilator mode to manage this patient initially is which of the following?

Accepted Answer

This patient is in impending respiratory failure due to a congestive heart failure (CHF)exacerbation.The arterial blood gas (ABG)also reveals mild hypercapnia and severe hypoxemia.With the proper treatment this exacerbation could be reversed fairly quickly.Non-invasive positive pressure ventilation (NPPV),in the form of bilevel positive airway pressure,is appropriate because of this.All the other choices require intubation.If the NPPV doesn't work to decrease the patient's respiratory failure then intubation would be the next step.

Question 2

A breath that is triggered,limited,and cycled by the mechanical ventilator is which of the following?

Accepted Answer

Breaths that are triggered by the mechanical ventilator are considered mandatory breaths because the ventilator is controlling the timing of the breath and delivering either a set volume or set pressure.

Question 3

During volume control ventilation a patient's airway resistance increases.This change will cause which of the following to occur?

Accepted Answer

During volume control ventilation,changes in lung characteristics cause changes in pressure.Increasing airway resistance causes an increase in the amount of pressure required to deliver the volume,thereby increasing peak airway pressure.

Question 4

A breath that is patient triggered,pressure targeted,and time cycled is which of the following?

Accepted Answer

Assisted breaths have characteristics of both mandatory and spontaneous breaths.In an assisted breath,all or part of the breath is generated by the ventilator,which does part of the work of breathing (WOB)for the patient.If the airway pressure rises above baseline during inspiration,which it does in this case,the breath is assisted.

Question 5

Which of the following is the minimum ventilator rate that is considered full ventilatory support?

Accepted Answer

Full ventilatory support is provided when the ventilator initiated rates are 8 breaths/minute or more.

Question 6

An assisted breath in the pressure-controlled continuous mandatory ventilation (PC-CMV)mode can be described by which of the following?

Accepted Answer

An assisted breath is always patient triggered.In the pressure control or targeted mode the pressure set is the pressure limit and the inspiratory time setting ends inspiration (cycle).Therefore,the correct answer is patient triggered,pressure limited,time cycled.The time triggered,pressure limited,time cycled breath is a mandatory breath in the pressure-controlled continuous mandatory ventilation (PC-CMV)mode.The time triggered,pressure limited,pressure cycled breath describes an intermittent positive pressure breathing (IPPB)-type mandatory breath.The patient triggered,volume limited,volume cycled is a mandatory breath in the volume-controlled continuous mandatory ventilation (VC-CMV)mode.

Question 7

A patient has recently been diagnosed with obstructive sleep apnea.The most appropriate treatment includes which of the following?

Accepted Answer

Continuous positive airway pressure (CPAP)is an accepted method used to treat obstructive sleep apnea.Noninvasive positive pressure ventilation (NPPV)would be appropriate if the patient had central sleep apnea,since there would be no respiratory efforts during the apnea periods.Pressure support ventilation (PSV)and Pressure controlled continuous mandatory ventilation (PC-CMV)would require the patient to be intubated.

Question 8

Full ventilatory support is provided by which of the following modes?

Accepted Answer

Full ventilatory support is provided when the ventilator-initiated rates are set at 8 breaths/minute or more in the continuous mandatory ventilation (CMV)or synchronized intermittent mandatory ventilation (SIMV)modes with either pressure-control or volume-control.

Question 9

The ventilator mode that would be most appropriate to iatrogenically induce hyperventilation to manage a closed head injury patient with severely elevated intracranial pressure (ICP)is which of the following?

Accepted Answer

In order to deliberately hyperventilate a patient,each breath needs to be a machine breath (either volume or pressure).The only mode from the choices given that does that is the pressure-controlled continuous mandatory ventilation (PC-CMV)mode.Volume support ventilation (VSV)is a patient triggered,volume-targeted,flow cycled mode of ventilation that has no back-up rate and therefore is a purely spontaneous mode.Airway pressure release ventilation (APRV)is designed to provide two levels of continuous positive airway pressure (CPAP)and to allow spontaneous breathing at both levels when spontaneous effort is present.If the patient is not breathing spontaneously,APRV resembles pressure-controlled inverse ratio ventilation (PCIRV)and could potentially elevate the patient's already elevated intracranial pressure (ICP).Volume-controlled synchronized intermittent mandatory ventilation (VC-SIMV)actually could be made to hyperventilate the patient if the rate is set high enough.The SIMV mode is actually used to reduce the effect of patient hyperventilation on acid-base balance.This happens because only the set rate is a ventilator breath;the rest are patient triggered with the patient's own tidal volume.

Question 10

A hemodynamically unstable patient being ventilated in the volume-controlled continuous mandatory ventilation (VC-CMV)mode is triggering inspiration at a rate of 25 breaths/minute and has the following arterial blood gas results: pH 7.50,partial pressure of carbon dioxide (P_aCO₂)30 mm Hg,partial pressure of oxygen (P_aO₂)98 mm Hg,arterial oxygen saturation (S_aO₂)100%,bicarbonate (HCO₃^-)24 mEq/L.The respiratory therapist should peform which of the following?

Accepted Answer

This patient has ventilator induced hyperventilation as evidenced by the partial pressure of carbon dioxide (P_aCO₂)of 30 mm Hg with a trigger rate of 25 breaths/minute.Switching to the volume-controlled synchronized intermittent mandatory ventilation (VC-SIMV)mode will decrease the number of ventilator breaths the patient triggers by allowing the patient to breathe spontaneously between the mandatory ventilator breaths.This will reduce the patient's minute ventilation and normalize the P_aCO₂ and pH.Another potential advantage is to put less of a strain on an already hemodynamically unstable patient.There is nothing in this patient's scenario that suggests extubation and use of noninvasive positive pressure ventilation (NPPV).Switching to the pressure-controlled continuous mandatory ventilation (PC-CMV)mode will most likely not correct the patient's problem because the patient will still be able to trigger ventilator set breaths and could continue to hyperventilate.Although sedating and medically paralyzing the patient could normalize the patient's acid-base balance,it is not the treatment of choice because of the hemodynamic instability of the patient.

Question 11

Partial ventilatory support can be provided by which of the following ventilator modes? 1)Pressure Controlled Continuous Mandatory Ventilation (PC-CMV)set rate 8 breaths/minute 2)Volume Controlled Synchronized Intermittent Mandatory Ventilation (VC-SIMV)set rate 4 breaths/minute 3)Pressure Controlled Synchronized Intermittent Mandatory Ventilation (PC-SIMV)set rate 10 breaths/minute 4)VC- MMV set V_e8 L/minute

Accepted Answer

Continuous mandatory ventilation (CMV)is a full ventilatory support mode.Therefore,Pressure Controlled Continuous Mandatory Ventilation (PC-CMV)rate 8 breaths/minute is not partial ventilatory support.A ventilator rate setting of 8 breaths/minute or more is also considered full support.Therefore,even though Pressure Controlled Synchronized Intermittent Mandatory Ventilation (PC-SIMV)could be partial ventilatory support,it is full support because of the set rate of 10 breaths/minute.Volume Controlled Synchronized Intermittent Mandatory Ventilation (VC-SIMV)with a set rate of 4 breaths/minute is partial ventilatory support and MMV can be partial ventilatory support when the patient is participating in the work of breathing (WOB)to maintain effective alveolar ventilation.

Question 12

The pressure-time scalar shown in the figure represents which of the following?

Accepted Answer

The figure shows two levels of pressure-control ventilation.The higher level,around 22 cm H₂O is the mandatory ventilator breaths.The lower level shows spontaneous breaths with a pressure support of approximately 15 cm H₂O.Baseline (PEEP)is at 5 cm H₂O.

Question 13

The ventilator mode that allows the patient to breathe spontaneously between operator selected time-triggered volume or pressure-targeted breaths is which of the following?

Accepted Answer

The synchronized intermittent mandatory ventilation (SIMV)mode allows the patient to breathe spontaneously between operator mandatory ventilator breaths.During these spontaneous breaths the baseline pressure may be set at ambient pressure or above ambient pressure.In addition,pressure support may be used during the spontaneous breathing period.Pressure support ventilation (PSV)has no time-triggered breaths,nor does it have volume-targeted breaths.Continuous mandatory ventilation (CMV)does not allow for spontaneous breathing,it only allows the patient to trigger the mandatory ventilator breath.Airway pressure release ventilation (APRV)does not have volume-targeted breaths.It is designed to be two levels of continuous positive airway pressure (CPAP)where the patients breathe spontaneously at both levels.

Question 14

What type of breath occurs when the ventilator controls the timing,tidal volume,or inspiratory pressure?

Accepted Answer

Mandatory breaths occur when the ventilator is time triggered,volume or pressure targeted.Spontaneous breaths are patient triggered and the volume or pressure is based on the patient's demand and lung characteristics.Assisted breaths have characteristics of both mandatory and spontaneous,the patient triggers the breath,the ventilator delivers a set pressure or volume,and the airway pressure rises above baseline during inspiration.The term control is not used to describe the type of breath delivery.This term is used to describe the variable that is being manipulated as the target for the breaths (for example: pressure control or volume control).

Question 15

When a patient does not breathe spontaneously while in the airway pressure release ventilation (APRV)mode,the pressure-time scalar looks like that of which of the following?

Accepted Answer

The airway pressure release ventilation (APRV)mode is a dual mode of ventilation that allows the patient to breathe spontaneously at two levels of continuous positive airway pressure (CPAP).Both pressure levels are time triggered and time cycled.When the patient is not spontaneously breathing the pressure-time scalar will alternate between the two CPAP levels.The higher pressure,or P_high is set longer than the P_low.The pressure-time scalar for this mode will then appear as pressure-controlled inverse ratio ventilation (PCIRV).

Question 16

A home care patient diagnosed with central sleep apnea would benefit from which of the following modes of ventilation?

Accepted Answer

Noninvasive Positive Pressure Ventilation (NPPV)is appropriate for this patient because during the periods of apnea there are no respiratory efforts.Continuous Positive Airway Pressure (CPAP)is an accepted method used to treat obstructive sleep apnea.Pressure Support Ventilation (PSV)and Pressure Controlled Intermittent Mandatory Ventilation (PC-CMV)would require the patient to be intubated.

Question 17

A 28-year-old male has arrived in the emergency department following a motor vehicle accident.He has a Glasgow Coma Score of 14.Chest x-ray reveals 5 ribs broken anteriorly in 2 areas each.Physical assessment reveals paradoxical movement of the chest.Breath sounds are diminished and the trachea is midline.Arterial blood gas on nonrebreathing mask is: pH 7.53,partial pressure of carbon dioxide (P_aCO₂)is 25 mm Hg,partial pressure of oxygen (P_aO₂)is 59 mm Hg,arterial oxygen saturation (S_aO₂)93%,bicarbonate (HCO₃^-)23 mEq/L.The respiratory therapist should recommend which of the following for this patient?

Accepted Answer

The arterial blood gas shows that the patient is ventilating,as evidenced by the partial pressure of carbon dioxide (P_aCO₂)of 25 mm Hg.Therefore,this patient does not need to be intubated and ventilated at this time.This also means that the patient does not require noninvasive positive pressure ventilation (NPPV).The patient does have an oxygenation problem,as evidenced by the partial pressure of oxygen (P_aO₂)of 59 mm Hg while on a nonrebreathing mask.This is an indication for continuous positive airway pressure (CPAP).

Question 18

If flow or sensitivity is set incorrectly,which of the following is most likely to occur during the continuous mandatory ventilation (CMV)mode?

Accepted Answer

High or low flow rate settings can cause the patient to be out of synchrony with the ventilator.The higher the flow rate the shorter the inspiratory time.Incorrect sensitivity settings can lead to auto-triggering or "locking out" the patient.

Question 19

Of the following breath descriptions,which one is considered spontaneous?

Accepted Answer

Flow triggered and pressure triggered mean that the patient has initiated the breath.Pressure limited and volume limited mean that either one of these variables is not allowed to be exceeded during a breath.This occurs with either ventilator or assisted breaths.Patient triggered could either be pressure or flow and could be part of a spontaneous breath as long as the pressure during inspiration does not rise above the baseline setting.During spontaneous breathing the patient will control both the beginning and the ending of the breath.

Question 20

Which mode of ventilation is shown in the pressure-time scalar in the figure?

Accepted Answer

The pressure-time scalar shows all mandatory breaths,two time triggered and one pressure triggered.This means there is a combination of mandatory and assisted breaths.The scalar shows a peak inspiratory pressure that is not held.This means that the mode being shown is volume-controlled continuous mandatory ventilation (VC-CMV).

Quiz 5: Selecting the Ventilator and the Mode