Respiratory monitors and equipment 2

Question 1

Describe an airflow obstruction capnograph.

Answer 1

prolonged upstroke with increased alpha angle

Question 2

Examples of an airflow obstruction include

Answer 2

COPD, bronchospasm, kinked ETT

Question 3

Describe cardiac oscillations capnograph

Answer 3

oscillations in the capnograph waveform from C to D

Question 4

Cardiac oscillations are more common in

Answer 4

children because of close proximity of the heart to the lungs

Question 5

Cardiac oscillations are caused by the

Answer 5

heart beating against the lungs

Question 6

What is a curare cleft?

Answer 6

spontaneous breaths during mechanical ventilation

Question 7

If present during spontaneous ventilation, the presence of a curare cleft suggests

Answer 7

inadequate muscle relaxant reversal (lack of synchronization between intercostal muscles and diaphragm)

Question 8

Why might we see low EtCO2?

Answer 8

hyperventilation
decreased CO2 production
increased alveolar dead space

Question 9

Examples of low EtCO2 due to hyperventilation include

Answer 9

light anesthesia, metabolic acidosis

Question 10

Examples of low EtCO2 due to low Co2 production include

Answer 10

hypothermia

Question 11

Examples of low EtCO2 due to increased alveolar dead space include

Answer 11

hypotension
pulmonary embolism

Question 12

Why could we see increased EtCO2 with a normal plateau?

Answer 12

increased CO2 production or decreased alveolar ventilation

Question 13

Examples of increased EtCO2 due to increased CO2 production include

Answer 13

MH, sepsis, fever, hyperthyroidism

Question 14

Examples of increased EtCO2 due to decreased alveolar ventilation include

Answer 14

hypoventilation
narcotics

Question 15

How do we know if the capnography is due to inspired CO2?

Answer 15

look at the baseline. it does not return to zero–> rebreathing

Question 16

Why could we see rebreathing?

Answer 16

exhausted CO2 absorbent
incompetent expiratory valve
hole in the inner tube of a Bain system
inadequate FGF with Mapleson circuit
rebreathing under the drapes in a patient who is not intubated

Question 17

An incompetent inspiratory valve will appear on capnography as

Answer 17

a decreased slope during the inspiratory phase (widened beta angle)
waveform may or may not reach zero, depending on the FGF

Question 18

What would a leak in the sample line during positive pressure ventilation appear as?

Answer 18

the beginning of the plateau is low because alveolar gas is diluted when atmospheric air is aspirated into the sample line

Question 19

When could a biphasic expiratory plateau occur?

Answer 19

single-lung transplant b/c alveolar gas from the transplanted lung and the diseased lung may have different time constants

Question 20

Causes of increased EtCO2 include

Answer 20

increased CO2 production and delivery to the lungs
decreased alveolar ventilation
equipment malfunnction

Question 21

Causes of decreased EtCo2 include

Answer 21

decreased CO2 production and delivery to the lungs
increased alveolar ventilation
equipment malfunction

Question 22

For EtCO2 to be detected, the following requirements must be met:

Answer 22

1. CO2 must be produced during metabolism
2. There must be an adequate pulmonary blood flow to deliver CO2 to the lungs for elimination
3. There must be an adequate ventilation to transport CO2 to the breathing circuit
4. There must be an intact sampling system

Question 23

What are the two things that you must consider when answering a question about changes in end-tidal CO2?

Answer 23

1. What is the cause?
2. Does this affect the PaCO2 to EtCO2 gradient

Question 24

Equipment malfunction that can cause increased EtCO2 includes

Answer 24

rebreathing
CO2 absorbent exhaustion
unidirectional valve malfunction
leak in breathing circuit
increased apparatus dead space

Question 25

Equipment malfunction that can cause decreased EtCO2 includes

Answer 25

Ventilator disconnect esophageal intubation poor seal with ETT or LMA sample link leak airway obstruction apnea

Question 26

What are examples of increased alveolar ventilation that can result in decreased EtCO2

Answer 26

hyperventilation inadequate anesthesia metabolic acidosis (if spontaneous ventilation) medication side effect

Question 27

What are examples of decreased alveolar ventilation that can result in increased EtCO2?

Answer 27

hypoventilation CNS depression residual NMB COPD high spinal neuromuscular disease metabolic alkalosis medication side effect

Question 28

What are causes of increased CO2 production and delivery to the lungs that can result in increased EtCO2?

Answer 28

increased BMR malignant hyperthermia thyrotoxicosis fever sepsis seizures laryngoscopy tourniquet or vascular clamp removal sodium bicarbonate administration shivering increased muscle tone (after NMB reversal) medication side effect

Question 29

What are causes of decreased CO2 production and delivery to the lungs that can result in decreased EtCO2?

Answer 29

decreased BMR increased anesthetic depth hypothermia decreased pulmonary blood flow decreased cardiac output hypotension pulmonary embolus V/Q mismatch medication side effect pain/anxiety (if breathing spontaneously)

Question 30

Select the statements that MOST accurately describe pulse oximetry (select 2). a. oxygenated hemoglobin absorbs light at 940 nm b. at the peak of the waveform, the ratio of arterial blood to venous blood is reduced c. it is based on the Beer-Lambert law d. it is based on the Doppler effect

Answer 30

a. oxygenated hemoglobin absorbs light at 940 nm c. It is based on the Beer-Lambert law

Question 30

Select the statements that MOST accurately describe pulse oximetry (select 2). a. oxygenated hemoglobin absorbs light at 940 nm b. at the peak of the waveform, the ratio of arterial blood to venous blood is reduced c. it is based on the Beer-Lambert law d. it is based on the Doppler effect

Answer 30

a. oxygenated hemoglobin absorbs light at 940 nm c. It is based on the Beer-Lambert law

Question 31

The pulse oximeter is based on the _______

Answer 31

Beer-Lambert Law

Question 32

What does the Beer Lambert law describe?

Answer 32

it relates the intensity of light transmitted through a solution (blood) and the concentration of the solute (hemoglobin) within the solution

Question 33

Red light is absorbed at

Answer 33

660 nm

Question 34

Red light is preferentially absorbed by

Answer 34

deoxyhemoglobin (higher in venous blood)

Question 35

Near-infrared light is absorbed at

Answer 35

940 nm

Question 36

Near-infrared light is absorbed by

Answer 36

oxyhemoglobin (higher in arterial blood)

Question 37

As a general rule, monitoring sites ________________ have faster response times

Answer 37

closer to the central circulation (forehead and ear will be more responsive than the toe)

Question 38

What is the SpO2 equation?

Answer 38

SpO2= oxygenated hbg/ (oxygenated hbg + deoxygenated Hbg) x 100%

Question 39

At the trough of the pulse waveform, there is a

Answer 39

greater amount of venous blood in the tissue sample

Question 40

At the peak of the pulse waveform, there is a

Answer 40

greater amount of arterial blood in the tissue sample

Question 41

When SpO2 is monitored on the head or esophagus, the Trendelenburg position can cause

Answer 41

venous engorgement resulting in a falsely decreased SpO2 measurement