Chapter 11 - Support Oxygenation and Ventilation Flashcards Preview

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1

You are called to the ER to help in the assessment and care of a patient admitted with CHF and severe pulmonary edema. While starting an intravenous line, the physician tells you to give the patient O2. You would start the following:

  1. A nonrebreathing mask
  2. A nasal cannula at 4 L/min
  3. A simple face mask at 5 L/min
  4. A 35% air-entrainment mask

1

Patients with CHF and pulmonary edema typically have severe hypoxemia and compromised myocardial function. In these cases, the goal is to provide high concentrations of oxygen (60% or more). Of the devices listed, only the nonrebreathing mask can deliver high FIO2s. You might also recommend CPAP with 100% O2 for this patient, since the elevated airway pressure can help reduce venous return and alleviate pulmonary congestion.

2

Assuming all else being equal, which of the following BiPAP settings would result in the greatest increase in FRC?

  1. EPAP = 5 cm H2O; IPAP = 15 cm H2O
  2. EPAP = 10 cm H2O; IPAP = 20 cm H2O
  3. EPAP = 5 cm H2O; IPAP = 25 cm H2O
  4. EPAP = 15 cm H2O; IPAP = 30 cm H2O

4

The resting lung volume or FRC during BiPAP is primarily determined by the EPAP pressure setting. All else being equal, the higher the EPAP pressure, the larger the FRC.

3

Absolute contraindications to turning or rotating critical ill patients include which of the following?

  1. Unstable cardiac arrhythmias: No; Unstable spinal cord injuries: Yes; Ventilatory dependency: No
  2. Unstable cardiac arrhythmias: No; Unstable spinal cord injuries: No; Ventilatory dependency: Yes
  3. Unstable cardiac arrhythmias: Yes; Unstable spinal cord injuries: Yes; Ventilatory dependency: No
  4. Unstable cardiac arrhythmias: Yes; Unstable spinal cord injuries: Yes; Ventilatory dependency: Yes

3

Absolute contraindications to turning or rotating critical ill patients include unstable spinal cord injuries, unstable cardiac arrhythmias that may require defibrillation or cardiac compression, and traction of arm abductors. Relative contraindications include severe diarrhea, marked agitation, a rise in ICP, large drops in blood pressure (>10%), worsening dyspnea, hypoxia, and cardiac arrhythmias not likely to require defibrillation or cardiac compression.

4

A postoperative 40-year-old 70 kg (154 lb) patient is breathing spontaneously at a rate of 28/min with a delivered FIO2 of 0.4. The following arterial blood gases are obtained:


____Blood GasespH7.24PaCO238 torrHCO323 mEq/LBE-1PaO2610 torrSaO2100%
Based on the above data, VC, SIMV ventilation is instituted with a tidal volume of 650 mL and an FIO2 of 0.5. The SIMV rate should be set at which of the following?
  1. 2/min
  2. 6/min
  3. 12/min
  4. 28/min

3

Most patients started on mechanical ventilation are initially provided full ventilatory support. The initial rate setting for patients receiving full ventilatory support ranges from 8-12 breaths per minute.

5

 

A 43-year-old 50 kg woman receiving 40% oxygen via T-tube has been admitted to the ICU following gastric surgery. Here attending doctor orders volume control assist/control ventilation (VC,A/C). Which of the following would be the most appropriate initial ventilator settings for this patient?

 

                 VT                   Rate                         FIO2    

A               500                 10                          0.070

             700                  8                           0.60

C               400                 12                          0.50

             600                 20                          0.40

  1. A
  2. B
  3. C
  4. D

3

Given this patient's weight, a tidal volume in the 300 to 500 mL range (6 to 10 mL/kg) is in order. The rate should be in the 8–12/min range. Given that she is already receiving 40% oxygen, it would be wise to provide an initial small increment in FIO2 as she is first placed on the ventilator.

6

A doctor requests that you begin noninvasive positive pressure ventilation (NPPV) on a COPD patient in hypercapnic respiratory failure. Which of the following setting would you choose?

  1. IPAP 20 cm H2O; EPAP 5 cm H2O; assist-control mode
  2. IPAP 30 cm H2O; EPAP 5 cm H2O; assist (spontaneous only) mode
  3. IPAP 20 cm H2O; EPAP 0 cm H2O; assist-control mode
  4. IPAP 10 cm H2O; EPAP 10 cm H2O; assist (spontaneous only) mode

1

To initiate NPPV to manage a patient in hypercapnic respiratory failure, choose a suitable ventilator and appropriate interface; explain the therapy to the patient and provide reassurance; initiate NPPV in the assist-control mode while securing the airway interface; titrate IPAP/VT to patient comfort (usually < 25 cm H2O) and EPAP/PEEP to 5–10 cm H2O to improve oxygenation and/or overcome auto-PEEP; and titrate FIO2 to maintain SpO2 > 90%. Continue to coach/reassure the patient.

7

To minimize hypoxemia, a patient in congestive heart failure with cardiogenic pulmonary edema should be placed in what position?

  1. Trendelenburg
  2. supine
  3. semi-Fowler's
  4. prone

3

It is common for patients with congestive heart failure to experience shortness of breath while lying flat or in a head-down position (orthopnea). This is due to fluid displacement into the thorax and lungs and worsening of the pulmonary edema and hypoxemia. To improve gas exchange and minimize the work of breathing, such patients should generally be positioned in a semi-Fowler's or Fowler's position.

8

A patient receiving pressure support ventilation (PSV) exhibits repeated overshooting of the set pressure early in the airway pressure waveform. Which of the following is the likely cause of this problem?

  1. rise time set too slow/low
  2. expiratory trigger set too low
  3. rise time set too fast/high
  4. expiratory trigger set too high

3

To avoid asynchrony during PSV requires proper setting of the inspiratory trigger, rise time and (if adjustable) the flow termination criterion or 'expiratory trigger.' Overshooting or spiking of the set pressure early in the airway pressure waveform (aka a 'left dog ear') indicates that the rise time is set too fast/high and should be lowered until the pressure spike disappears.

9

You observe the following graphics display on a patient receiving volume controlled A/C ventilation. The most significant problem is:

  1. a leak in the patient-ventilator system
  2. inadequate inspiratory flow setting
  3. improper sensitivity setting
  4. presence of auto-PEEP/air-trapping

2

The primary problem apparent in this graphic is the 'scalloping' of the inspiratory airway pressure waveform (Paw) occurring AFTER the beginning of inspiration. Normally, pressure should rise after inspiration begins. A drop in pressure ('scalloping') during flow-limited volume control ventilation indicates inadequate inspiratory flow. The upper expiratory flow waveform also suggests slight auto-PEEP.

10

A patient is admitted to the Emergency Department comatose with suspected smoke inhalation. After confirming airway patency, which of the following should you do FIRST?

  1. Measure the SpO2
  2. Initiate 100% oxygen
  3. Obtain an arterial blood gas
  4. Request a stat chest X-ray

2

In cases of suspected smoke inhalation, it is likely that the patient is suffering from hypoxemia due to a high concentration of carboxyhemoglobin (COHb) in his blood, which requires immediate treatment. Unless a hyperbaric chamber is available, the only way to treat carbon monoxide poisoning is to provide supplementary O2, ideally 100%. Note also that standard pulse oximetry cannot reveal the presence of COHb and the SaO2 reported by blood gas analysis is simply a calculated value based on the PO2 and pH. To measure the actual amount of COHb in the patient's blood (after administering 100% O2), you would need to perform co-oximetry.

11

A patient is being mechanically ventilated in the SIMV volume control (VC) mode at a rate of 4/min. The spontaneous respiratory rate increases from 12 to 35/min. Which of the following is the most appropriate action?

  1. Increase the SIMV rate
  2. Add 10 cm H2O PEEP
  3. Initiate pressure control
  4. Sedate the patient

1

In the SIMV mode, a significant increase in the total respiratory rate indicates increased work of breathing. To maintain a normal patient rate of breathing, you can increase the machine rate and/or add presure support.

12

While monitoring a patient receiving volume control A/C ventilation, you note the following:

You should:

  1. decrease the high pressure limit to 45 cm H2O
  2. increase the high respiratory rate alarm to 40/min
  3. decrease the low tidal volume alarm to 500 mL
  4. decrease the low pressure alarm to 10 cm H2O

1

Recommended alarm settings are as follows: Low VT: 10-15% below the set or targeted tidal volume; High Pressure Limit: 10-15 cm H2O above average peak pressure, Low Pressure Alarm: 5-10 cm H2O below average peak pressure, High Respiratory Rate Alarm (for adults): 30-35/min. In this case the High Pressure Limit is 30 cm H2O above the peak inspiratory pressure and should be decreased to 40-45 cm H2O.

13

A doctor requests that you use positioning to improve the oxygenation of an adult patient with lobar pneumonia of the right middle and lower lobes. Which of the following positions would you select?

  1. Right lateral decubitus position
  2. Trendelenburg position
  3. Left lateral decubitus position
  4. Semi-Fowler's position

3

In patients with unilateral lung disease, placing the good lung in the dependent or "down" position tends to improve oxygenation. Oxygenation improves because gravity directs more blood flow to the well-ventilated dependent alveoli. In conditions such as lung abscess, however, the good lung normally is kept in the up position. This helps prevent blood or pus from entering the good lung. Placement of the good lung up (and diseased lung down) is also indicated with unilateral pulmonary interstitial emphysema (PIE).

14

While suctioning an adult patient receiving ventilatory support, you note the heart rate decreases abruptly from 92 to 55/min. Which of the following actions could help prevent or minimize this problem?

  1. Recommend a bolus of atropine before suctioning
  2. Instill lidocaine (Xylocaine) into the trachea before suctioning
  3. Increase the FIO2 to 1.0 for at least 30-60 seconds before suctioning
  4. Give the patient 2 MDI puffs of beclomethasone before suctioning

3

Most cardiac arrhythmias during suctioning are due to arterial hypoxemia. The best way to prevent or minimize arterial hypoxemia during suctioning is to preoxygenate the patient with 100% O2 for at least 30-60 seconds prior to beginning the procedure. Assuring short suction times (< 15 sec) can also help prevent hypoxemia during suctioning. For severely hypoxemia patients receiving ventilatory support with PEEP (e.g., ARDS patients), preoxygenation and suctioning using a closed catheter system is the best way to avoid arterial hypoxemia. Closed catheter systems allow suctioning while maintaining ventilator-controlled PEEP and FIO2.

15

You are trying to wean an alert intubated patient off full ventilatory support using an "on ventilator" CPAP protocol with 40% O2. Early in the initial effort his respiratory rate increases from 24 to 30/min and you start to observe some use of his accessory muscles of respiration. Which of the following would be your first action?

  1. Restore the patient to full ventilatory support
  2. Apply 5-10 cm H2O pressure support
  3. Increase the FIO2 to 0.50
  4. Extubate the patient and re-evaluate

2

Your first action in this case should be to add a low level of pressure support ventilation (PSV) to the CPAP. PSV can augment a patient's spontaneous tidal and thus allow for a more efficient breathing pattern/lower respiratory rate. PSV also can help unload the respiratory muscles from the extra work of breathing imposed by artificial airways and thus further aid in weaning.

16

For which of the following patients would application of noninvasive positive pressure ventilation (NPPV) likely be most difficult?

  1. A patient with acute exacerbation of COPD
  2. A patient with Duchenne muscular dystrophy
  3. A patient copious secretions requiring suctioning
  4. A patient with cardiogenic pulmonary edema

3

The presence of copious secretions requiring suctioning is a relative contraindication against NPPV, making its application potentially difficult. Other relative contraindications include 1) confusion, agitation and a decreased level of consciousness; 2) impaired upper airway reflexes such as dysphagia; 3) morbid obesity; 4) acute sinusitis or otitis media; and 5) allergy or hypersensitivity to the mask materials. Acute exacerbation of COPD, chronic neuromuscular disorders (like Duchenne muscular dystrophy) and cardiogenic pulmonary edema are all potential indications for application of NPPV.

17

A doctor orders a lung recruitment maneuver for a patient with ARDS who was just intubated and placed on pressure control A/C ventilation. Prior to implementing the maneuver you would want to assess which of the following?

  1. arterial blood pressure
  2. oxygen consumption
  3. renal output and BUN
  4. physiologic deadspace

1

Because a recruitment maneuver (RM) can decrease cardiac output and tissue perfusion (due to high intrathoracic pressures), RMs should only be conducted on hemodynamic stable patients, most commonly defined as those having a mean arterial pressure ≥ 60-65 mm Hg that has not required recent alterations in vasoactive or inotropic drug dosing.

18

To adjust patient oxygenation during high-frequency oscillation ventilation (HFOV), you manipulate which of the following settings:

  1. oscillation frequency
  2. mean pressure (Pmean)
  3. % inspiratory time
  4. amplitude/power

2

The main determinant of oxygenation during HFOV is the mean airway pressure (Pmean). In general, the higher Pmean, the larger the FRC and better the oxygenation for a given FIO2.

19

An 80 kg patient is receiving volume control SIMV at a rate of 4 with a tidal volume of 700 mL. Over the last hour his spontaneous respiratory rate has increased from 12 to 37/min. Which of the following is the most appropriate action?

  1. increase the SIMV rate
  2. add 10 cm H2O PEEP
  3. switch to control mode
  4. sedate the patient

1

The rise in spontaneous rate suggests that minute ventilation being provided by the ventilator (4 x 700 mL = 2.8 L/min) is not meeting the patient’s needs. After ruling out causes (anxiety, fever, etc.), the best action would be to at least temporarily increase the ventilator minute volume by providing a normal rate (10-12/min). Alternatively, you could increase the pressure support level to increase the spontaneous breath volume.

20

A 70 kg patient with a history of COPD is being mechanically ventilated because of respiratory failure. Current ventilator settings and arterial blood gas results are as follows:
 

Ventilator Settings                                   Blood Gases

Mode                              Vol Ctrl A/C                                   pH          7.38

VT                                                600 mL                                         PaCO2    50 torr

PEEP                               0 cm H2O                                      SaO2        91%

You should recommend which of the following?

  1. Increase tidal volume to 750 mL
  2. Set the rate at 6/min
  3. Add 8 cm H2O PEEP
  4. Maintain present settings

4

The blood gas indicates that this patient has fully compensated respiratory acidosis. Because the acidosis is fully compensated, ventilation should remain unchanged. Regarding oxygenation, the target range for PaO2 in COPD patients who are CO2 retainers such as this patient, is 50 to 70 torr. Consequently, the settings should NOT be changed at this time.

21

A doctor requests that you use positioning to improve the oxygenation of an adult patient with lobar pneumonia of the right middle and lower lobes. Which of the following positions would you select?

  1. right lateral decubitus position
  2. Trendelenburg position
  3. left lateral decubitus position
  4. semi-Fowler's position

3

In patients with unilateral lung disease, placing the good lung in the dependent or "down" position tends to improve oxygenation. Oxygenation improves because gravity directs more blood flow to the well-ventilated dependent alveoli. However, in conditions such as lung abscess or unilateral bleeding, the good lung normally is kept in the up position. This helps prevent blood or pus from entering the good lung. Placement of the good lung up (and diseased lung down) is also indicated with unilateral pulmonary interstitial emphysema (PIE).

22

A 60 kg patient receiving mechanical ventilation has the following ventilator settings and arterial blood gas results:
 

Ventilator Settings                              Blood Gases

Mode                          Vol Ctrl SIMV                                pH           7.56

VT                                           500 mL                                        PaCO2      26 torr

Set Rate                      14/min                                           HCO3        22 mEq/L Spon Rate                   0                                                   PaO2          92 torr FIO2                                       0.55                                             SaO2          96%

Which of the following should you recommend?

  1. Increase the inspiratory time
  2. Increase the tidal volume to 600 mL
  3. Decrease the FIO2 to 0.50
  4. Decrease the SIMV rate

4

The blood gas indicates uncompensated respiratory alkalosis. To restore the pH back down to normal, you need to increase the PaCO2. To increase the PaCO2 you need to reduce the patient's minute ventilation. In this case the best option would be to decrease the SIMV rate. This may also stimulate some spontaneous breathing.

23

To lower the PaCO2 of a patient receiving high-frequency oscillation ventilation (HFOV), you would:

  1. decrease the oscillation frequency
  2. increase mean pressure (Pmean)
  3. increase the oscillation frequency
  4. increase the % inspiratory time

1

The settings that affect ventilation/CO2 elimination during HFOV are the amplitude and frequency of the pressure oscillations. Increasing the amplitude and decreasing the oscillation frequency lowers the PaCO2, whereas decreasing the amplitude and increasing frequency raises the PaCO2).

24

A doctor wants to provide full ventilatory support for an adult patient but allow her to control her own rate and CO2 levels. Which of the following modes of mechanical ventilation would you choose for this patient?

  1. control mode, rate = 12/min
  2. assist/control mode, rate = 10/min
  3. 5/10 cm H2O CPAP + pressure support
  4. SIMV mode, rate = 4/min

2

Assist/control mode (A/C) is indicated when full ventilator support is needed but the patient's rate results in acceptable PCO2. Assist/control mode allows patients to control their own rate and CO2 levels. Note that in many institutions, assist/control mode has largely been replaced by normal rate SIMV.

25

A doctor orders BiPAP for a patient with CHF and acute pulmonary edema just admitted to the Emergency Department. What FIO2 would you set for this patient?

  1. 0.4
  2. 0.6
  3. 0.8
  4. 1

4

Used to treat acute cardiogenic pulmonary edema, BiPAP aims to decrease the work of breathing, overcome the hypoxemia, and retard venous return. The treatment of hypoxemia is of utmost priority, with very high FIO2 often needed to assure adequate oxygenation. In general, 100% oxygen should be used.

26

Which of the following BiPAP settings would you initially select for a 165 lb COPD patient in hypercapnic respiratory failure needing NPPV in the emergency department?

  1. EPAP = 5 cm H2O; IPAP = 15 cm H2O; A/C (S/T) mode; rate 10
  2. EPAP = 0 cm H2O; IPAP = 10 cm H2O; A/C (S/T) mode; rate 10
  3. EPAP = 5 cm H2O; IPAP = 15 cm H2O; assist (spontaneous) mode only
  4. EPAP = 20 cm H2O; IPAP = 30 cm H2O; A/C (S/T) mode; rate 10

1

For a patient in hypercapnic respiratory failure needing NPPV the following settings are a good starting point: EPAP = 5 cm H2O; IPAP = 15 cm H2O; mode A/C (S/T); rate 10. Setting an EPAP of 5 cm H2O helps prevent auto-PEEP and air trapping, the IPAP of 15 cm H2O should increase the patients tidal volume and using the A/C mode with a rate of 10 assures that the patient will receive adequate ventilatory support even if apneic.

27

You are getting ready to suction an orally intubated patient receiving SIMV. To prevent hypoxemia during suctioning you should do which of the following?

  1. silence all alarms prior to suctioning
  2. set vacuum pressure to 100-120 mm Hg before procedure
  3. administer 100% O2 for 30-60 seconds before suctioning
  4. maintain the set FIO2 and increase PEEP prior to suctioning

3

To prevent hypoxemia during suctioning of an intubated patient, you should administer 100% O2 for 30-60 seconds, ideally via the ventilator (without removing the circuit). Using an inline/closed suction system also is helpful in minimizing volume loss and hypoxemia.

28

In order for CPAP to be successful in treating hypoxemic respiratory failure, the patient must have:

  1. an adequate PaO2 on less than 50% O2
  2. a secure artificial airway in place
  3. adequate spontaneous ventilation
  4. a cardiac output greater than 5 L/min

3

CPAP alone does not provide ventilation, serving only to maintain the FRC and prevent alveoli from collapsing. Because this mode depends entirely on patient breathing efforts, to succeed the patient must have adequate spontaneous ventilation.

29

Which of the following conditions is an indication for the use of PEEP?

  1. tension pneumothorax
  2. pulmonary embolism
  3. pulmonary edema 
  4. asthma

3

PEEP (positive end-expiratory pressure) can help overcome the shunting and hypoxemia common in both cardiogenic and noncardiogenic pulmonary edema. In cardiogenic pulmonary edema, PEEP can help decrease venous return and thus decreases pulmonary blood flows and pressures. In noncardiogenic pulmonary edema (e.g., ARDS), PEEP opens collapsed alveoli and improves the V/Q ratio.

30

Continuous positive airway pressure (CPAP) is indicated as a treatment for:

  1. post-operative atelectasis
  2. acute exacerbation of COPD 
  3. hypercapnic respiratory failure
  4. acute pulmonary emboli

1

CPAP is indicated to treat hypoxemia due to shunting in patients with adequate spontaneous ventilation (e.g., ARDS, IRDS). CPAP is also used to treat patients with atelectasis (intermittent therapy), CHF/pulmonary edema (short term application) and sleep apnea (nocturnal application). CPAP is contraindicated if the patient cannot maintain adequate ventilation on their own, e.g., hypercapnic ventilatory failure, acute exacerbation of COPD.