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Anesthesia > Mechanical Ventilation > Flashcards

Mechanical Ventilation Flashcards

1
Q

On the Hallowell ventilator, the Maximum Working Pressure should be set to ____ cmH2O unless otherwise instructed.

a. 5
b. 10
c. 20
d. 40

A

C

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2
Q

What are two inappropriate intraoperative “rescues” when patients become “light”?

a. Bolus propofol & treat for pain
b. Treat for pain & anxiety
c. Turn up the isoflurane & put the patient on a ventilator
d. Bolus propofol & put the patient on a ventilator

A

C

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3
Q

_____________________ is a significant indicator to provide mechanical ventilation. (select all that apply)

a. Hypertension under anesthesia
b. Use of neuromuscular blocking agents
c. Bradycardia under anesthesia
d. Hypercapnia under anesthesia
e. Intrathoracic surgery
f. Tachycardia under anesthesia
g. Hypoventilation under anesthesia
h. Inadequate staffing

A

B, D, E, G

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4
Q

You should _____________ the gas anesthetic vaporizer setting when mechanically ventilating a patient.

A

lower

mechanical ventilation will make the patient go deeper

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5
Q

Over-ventilation can __________ respiratory alkalosis.

A

cause

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6
Q

What three parameters on the ventilator can be set by the operator? (choose 3 answers)

a. Respiratory Rate (RR)
b. Tidal Volume (TV)
c. Maximum Working Pressure Limit
d. PaCO2
e. Waste Removal Rate (WRR)

A

A, B, C

MWPL acts as a backup so the lungs are not injured

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7
Q

When weaning a patient from a mechanical ventilator, reducing the respiratory rate to ______ breathes per minute may be necessary before the patient will begin to breathe on their own.

a. 1-2
b. 2-5
c. 4-8

A

A

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8
Q

PEEP valves _______________ the pressure within the breathing circuit.

a. increase
b. decrease
c. have no effect

A

A

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9
Q

Using the numbers supplied, please choose the correct numbers to fill in the blanks.

  • Patient’s weight = 22 lbs
  • Tidal Volume = 10 ml/kg
  • MWP valve = 20 cmH2O
  • Respiration rate = 15 breaths per minute

This patient’s Tidal Volume would be ______ mls and its Minute Volume would be ______ mls.

a. 150 and 1350
b. 330 and 4950
c. 300 and 4500
d. 220 and 3300
e. 100 and 1500

A

Vt = 10 ml/kg x 11 kg = 110 mL

MV = Vt x RR = 100 x 15 = 1500

E

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10
Q

Dead space is:

a. Part of the respiratory tract where no gas exchange takes place
b. The negative pressure gradient created between the alveoli and the atmosphere
c. When the patient stops spontaneous ventilation
d. Created by inadequate ventilation

A

A

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11
Q

During _________________ ventilation, a negative pressure gradient is created between the alveoli and atmosphere.

A

spontaneous

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12
Q

The Hallowell Ventilator’s Inspiratory to Expiratory Ratio (I:E) is preset to _______________ .

a. 1: 2
b. 2: 1
c. 2: 2
d. 1: 1

A

A

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13
Q

Mechanical ventilation _______________________. (select all that apply)

a. Can quickly make a patient too deep
b. Can make a patient very cold
c. Produces a lot of waste anesthesia
d. Provides good pain control to the patient
e. Can cause a pneumothorax
f. Is intended to relieve the anesthetist of the necessity of patient monitoring
g. Can cause oxygen toxicity

A

A, B, C, E (barotrauma), G

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14
Q

True or false: Capnography is a useful tool in monitoring a patient on mechanical ventilation.

A

TRUE —> measures ETCO2

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15
Q

True or false: Most patients become bradycardic while being mechanically ventilated.

A

FALSE

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16
Q

All anesthetic agents depress normal instinct to breath. Healthy patients under anesthesia receive assisted ventilation intermittently to help prevent ______.

A

atelectasis (lung collapse)

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17
Q

What are the 6 major indications for the use of mechanical ventilation?

A
  1. large patient size, obesity
  2. space-occupying CNS disease
  3. hypoventilation
  4. intrathoracic surgery (open chest)
  5. intraoperative use of neuromuscular agents where paralysis of the patient is required
  6. inability to maintain steady anesthesia despite administering pain, stress, or inflammation
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18
Q

Why are ventilators that are able to adjust the amount of oxygen the patient breathes helpful?

A

can lower oxygen to avoid oxygen toxicity in surgeries longer than 6 hours

  • room air levels = 21%
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19
Q

At what PaCO2 levels is hypoventilation defined? What is the major cause of hypoventilation?

A

PaCO2 > 45 mmHg (hypercarbia)

low respiratory rate or low tidal volume —> anesthesia/sedatives, respiratory muscle fatigue, brain disease, lung disease

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20
Q

At what PaCO2 levels is hyperventilation defined? When does this occur?

A

PaCO2 < 35 mmHg (hypocarbia)

rapid breathing or deep breaths, decreased cellular metabolism (hypothermia)

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21
Q

What is FiO2?

A

fraction of inspired oxygen, % of oxygen inspired

  • 21% at sea level
  • 100% on anesthesia machines
22
Q

What is the purpose of a PEEP valve?

A

(positive end expiratory pressure)

added to the exhalation limb of the anesthesia machine to maintain a certain pressure in the lungs at the end of exhalation, preventing the alveoli from collapsing —> increases the pressure within the breathing circuit

23
Q

What is a normal PaO2? What are hypoxic levels?

A

PaO2 = 80-120 mmHg (generally 4-5x FiO2) —> those breathing 100% O2 should be 400-500 mmHg

PaO2 < 60 mmHg

24
Q

What are 6 causes of hypoxia?

A
  1. low inspired concentrations of oxygen delivered to the patient
  2. hypoventilation
  3. diffusion impairment caused by lung disease severe enough to slow the passage of O2 from alveoli to the blood stream
  4. shunt causing perfusion imbalance - air enters alveoli, but there is no circulation
  5. V/Q mismatch - perfusion without ventilation or vice versa
  6. severe anemia, carbon monoxide poisoning, methemoglobinemia (acetaminophen poisoning)
25
Q

What is minute volume? How is it calculated?

A

amount of gas/air going in and out of the lungs

RR x tidal volume (normal is 150-250 mL/kg/min)

26
Q

What is the difference between pressure-limited ventilation and volume-limited ventilation?

A

PLV = mechanical ventilation where a breath is given to a predetermined pressure regardless of volume, causing the tidal volume to vary due to pulmonary compliance and pressure

*VLV = mechanical ventilation where a breath is given to a predetermined tidal volume where minor changes to compliance is accommodated and minute ventilation is constant

27
Q

What does “bucking the ventilator” mean?

A

patient initiates breaths that are counteractive to the breaths from a ventilator

28
Q

What are the 4 major negative effects of mechanical ventilation?

A
  1. impedes venous return to the right side of the heart, causing low venous pressure
  2. pneumothorax due to added pressure tearing lung or bronchus
  3. oxygen toxicity when 100% O2 is breathed longer than 6-8 hours, manifesting as pulmonary edema
  4. decreased perfusion, decreased urine output, fluid retention
29
Q

What bellows are recommended for different sizes of patients?

A
  • SMALL = 0-300 mL = < 15 kg
  • MEDIUM = 300-1600 mL = > 15 kg
30
Q

What are the 3 steps to weaning a patient from the ventilator?

A
  1. lower the anesthesia until the patient is starting to take breaths on its own (turning the anesthetic completely off is usually not ideal so think ahead and start weaning the patient before anesthesia is completely over)
  2. lower the RR slowly so that you can watch for patient breathing and allow the patient some breaths on its own.
  3. when the patient is taking breaths on its own, you can disconnect and either place on the anesthesia machine alone or to room air
31
Q

What are 5 possible causes of patient-ventilator asynchrony (bucking the ventilator)?

A
  1. inadequate anesthetic depth
  2. hypoxemia
  3. hypercapnia
  4. hyperthermia
  5. inappropriate ventilator settings
32
Q

What are 4 possible causes of a pulse oximeter measuring less than 95%?

A
  1. check probe position and check waveform/heart rate
  2. check oxygen flow/supply
  3. check ET tube
  4. check mucous membrane color, pulses, blood gas
33
Q

What are 5 possible causes of true hypoxemia?

A
  1. oxygen supply
  2. pneumothorax
  3. atelectasis (V/Q mismatch)
  4. significant hypoventilation
  5. patient bucking the ventilator
34
Q

What are 8 possible causes of end tidal CO2 monitor alarms or measures > 50 mmHg?

A
  1. occluded ET tube
  2. excessive dead space
  3. rebreathing of exhaled gases
  4. pneumothorax
  5. patient bucking the ventilator (panting = dead space ventilation)
  6. hypercapnia
  7. hyperthermia
  8. respiratory rate or tidal volume too low
35
Q

What are 5 possible causes of true hypercapnia?

A
  1. pneumothorax
  2. patient bucking the ventilator (panting = dead space ventilation)
  3. inappropriate settings (RR or TV too low)
  4. hyperthermia
  5. excessive anesthetic depth
36
Q

What is the most common cause of air-leak sounds during inspiration?

A

ET tube cuff lead or tube dislodgement

37
Q

What are the 2 most common causes of fluid sounds during inspiration?

A
  1. mucus in ET tube or airways
  2. fluid in tubing
38
Q

What should be done if a patient is on ventilation and a power outage occurs?

A

disconnect the patient and hand ventilate

39
Q

What is the difference between spontaneous and mechanical ventilation?

A

natural negative pressure causes air to enter the lungs

positive pressure is applied and air is forced into the alveoli, where blood is prevented from returning to the chest and cardia (decreased circulation, increased intraocular and intracranial pressure)

40
Q

Why is it so important for patients with CNS disease to be properly ventilated?

A

cerebral blood flow is mostly affected by PaCO2 and when it increases, herniation will occur

41
Q

What are the major consequences associated with mechanical ventilation?

A
  • increased depth of anesthesia
  • decreased venous return and cardiac output
  • V/Q mismatch (increased O2, decreased perfusion or vice versa)
  • oxygen toxicity
  • hypothermia
  • infection/inflammation
  • hyperventilation = respiratory alkalosis
  • baro/volutrauma (can lead to pneumothorax)
  • incressed thoracic pressure
  • decreased pulmonary arterial flow
  • redistribution of renal blood flow (affects RAAS)
  • hepatic plasminogen activation
42
Q

If a patient is has a high ETCO2, what should be done before they are put on ventilation?

A
  • turn off vaporizer
  • disconnect breathing circuit from ET tube
  • cap the end
  • oxygen flush with patient disconnected
  • reconnect breathing circuit
  • turn down vaporizer by 50%

wait 10-12 minutes while supplementing 1-2 breaths per min

43
Q

What should be considered if the vaporizer is up, but the patient is still waking up?

A

MOST PATIENTS —> review pre-meds and add opioids, sedatives, or anti-inflammatories

FEW PATIENTS —> intraoperative rescue

44
Q

What intraoperative rescues should be considered for pain, stress/awareness, and inflammation?

A

PAIN = opioids at 1/3 premed dose (Fentanyl), Ketamine, Lidocaine, Dexmedetomidine

S/A = Acepromazine, Dexmedetomidine, Midazolam

INFLAM = Carprofen, Meloxicam, Dex Na Phos, Lidocaine

(remember: opioids can cause increase inflammation)

45
Q

What does the respiratory cycle consist of during mechanical ventilation?

A
  • gas pumped in during inspiration (Ti)
  • patient passively expires (Te)

Ti + Te = cycle

46
Q

How does mechanical ventilation compare to intermittent positive pressure ventilation?

A

IPPV is when the rebreather bag is pushed to the usual frequency and volume of respiratory cycle, which allows for some normal spontaneous breathing

(no spontaneous breathing during MV)

47
Q

What is the proper inhalation to exhalation ratio? What should the normal RR and tidal volume be?

A

1:2-3 —> exhalation is longer to allow for healthy circulation

  • 10-15 breaths/min
  • 10-15 mL/kg
48
Q

What is the difference between therapeutic and auto PEEP?

A

THERAPEUTIC = using a PEEP valve to create back pressure to exhalation to improve severely decreased oxygenation (sound circulation required)

AUTO = pressure left in alveoli due to ventilation can cause inhalation before complete exhalation and bronchospasm

49
Q

What are normal ETCO2, PaCO2, PaO2, and blood pH?

A

30-50 mmHg

35-45 mmHg

3-5x FiO2 (80-100 mmHg)

7.35-7.45

50
Q

What are 6 major contraindications where if mechanical ventilation is required, it should be done extremely carefully?

A
  1. bullous or emphysematous changes to lungs
  2. collapsing trachea
  3. chronically compressed lung lobes (pyothorax)
  4. severe V/Q mismatch
  5. respiratory/metabolic alkalosis
  6. decreased cardiac output from hypovolemia or shock
51
Q

What 3 things can high tidal volume lead to?

A
  1. hypotension
  2. volutrauma
  3. expansion edema
52
Q

What are 6 possible causes of bellows becoming less full or failing to fill?

A
  1. gas leaking
  2. inadequate fresh gas supply from anesthesia machine
  3. bellows have a hole, tear, or rip or is detached
  4. pop off valve not completely closed
  5. sodasorb canister is not appropriately placed
  6. loose one-way valve

Anesthesia (40 decks)

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