Patient Monitors and analyzers Flashcards
1
Q
What is one of the most important pieces of monitoring hardware available to RTs?
A
Pulse oximeter
2
Q
What information does a pulse oximeter offer?
A
Hemoglobin saturation
Heart rate
Perfusion index
Pulse amplitude
3
Q
What are the most common sites for placing a pulse oximeter?
A
Finger
Toe
Nose
Ear
Foot
forehead
4
Q
What two principles do pulse oximeters operate off of?
A
Optical plethysmography
Spectrophotometry
5
Q
What is the wavelength of the red portion of the light beam?
A
660 nm
6
Q
What is the wavelength of the infrared portion of the light beam?
A
930 nm
7
Q
In basic terms, how does a pulse oximeter work?
A
Shoots a beam of red and infrared light through the tissue where oxygen laden hemoglobin absorb the light. Unabsorbed light passes through and is picked up via a receptor where it is determined how loaded the hemoglobin are
8
Q
How come bones, venous blood, and tissue do not affect the saturation reading?
A
Their absorption is constant over short periods of time and oximeters are able to account for them
9
Q
What are the two main types of pulse oximeters?
A
Reusable
Disposable
10
Q
What kind of alarms can be equipped onto pulse oximeters?
A
Audible and visual alarms
10
Q
What are the 3 different sizes of pulse oximeters?
A
Adult
Pediatric
Neonatal
11
Q
What fancy new features do modern pulse oximeters offer?
A
Perfusion index
Pulse amplitude
Trends
Error messages
12
Q
What are the normal values for pulse oximetry in healthy individuals?
A
95-100
13
Q
At what point is sat considered low?
A
90%
14
Q
What factors can skew the results of a pulse oximeter?
A
Low blood perfusion
Motion
Dysfunctional hemoglobin
Venous pulsation
Dark nail polish
Dark skin pigmentation
Extreme anemia
Surrounding light
15
Q
If placing a pulse oximeter on a finger, where should the hand be placed?
A
At the heart level
16
Q
T/F: you must calibrate pulse oximeters between uses
A
False. Pulse oximeters cannot be calibrated
17
Q
What are normal values for end tidal CO2?
A
35-45 mmHg
18
Q
What is the purpose of end tidal CO2 monitoring?
A
Assess respiration
Assess placement of ET tubes
Assess adequacy of perfusion during CPR
Metabolic studies
19
Q
What are the types of CO2 monitors?
A
Capnometer
Capnograph
20
Q
Describe a capnometer
A
Continuously measures CO2 and displays discrete numbers
21
Q
Describe a capnograph
A
Measures CO2 during each inspiratory and expiratory cycle and displays both a CO2 waveform and numeric data
graph=waveform
22
Q
How do CO2 monitors work?
A
Use infrared absorption spectroscopy to measure the partial pressure of CO2 in exhaled gas
23
Q
What are the types of CO2 monitors?
A
Mainstream
Side stream
24
Describe mainstream CO2 monitors
Direct measurement of total CO2 in exhaled gas
25
Describe sidestream CO2 monitors
Sampling of exhaled gas in intubated patients and spontaneously breathing patients
26
What can interfere with the accuracy of CO2 monitors?
Water vapor in tubing
Atmospheric pressure
Anesthetic vapors
Nitrous effect
27
What mechanisms can be utilized in side stream CO2 monitors to ensure their accuracy?
Water traps
Filters
Nafion tubing
28
What are the 2 points of calibration for CO2 monitors?
Zero and 5%
29
T/F: CO2 monitors do not need to be calibrated
False. CO2 monitors need to be calibrated at regular intervals
30
What is the concentration of FeNO that is measured by nitric oxide detectors?
Parts per billion
31
What are exhaled nitric oxide monitors used for?
Marker for diagnosis of asthma
Monitor response to anti-inflammatory meds
Monitor adherence to asthma therapy
Predict upcoming asthma exacerbations
32
How are nitric oxide detectors calibrated?
Nitric oxide detectors are calibrated via linear validation using at least 3-point calibration, 0, 200 and 500 parts per billion
33
What is nitric oxide measurement based on?
Chemiluminescence analysis
34
What is highly recommended for the FeNO detector calibration process?
Stable temp
Stable pressure
Stable humidity
34
T/F: medical air can be used to calibrate FeNO detectors
False. Medical air is not recommended for calibrating FeNO detectors
35
What is a transcutaneous monitor?
A method of noninvasive monitoring that allows for continuous monitoring via a sensor applied to the body
Allows for blood gasses diffusing through the skin to be detected and estimated
36
What can transcutaneous oxygen and CO2 monitors provide?
Real time readings, trends, histograms, themistors temps and alarms
37
T/F: two separate sensors are required for transcutaneous oxygen and carbon dioxide monitoring
False. There can be 2 monitors or both fields can be monitors by 1
38
What is transcutaneous monitoring?
Transcutaneous monitoring is the method of choice to continuously and non-invasively monitor oxygenation AND ventilation
39
What is the variable measured by transcutaneous monitors?
tcPO2 and tcPaCO2
40
T/F: tcPO2 and tcPaCO2 are always equal to PaO2 and PaCO2
False. They are not always equal but are general good indicators of the values
41
How do transcutaneous tcPO2 sensors work?
Electrode heats skin to 109-113 degrees fahrenheit
Arterial blood to dermal capillary increases
O2 diffuses through the sensors membrane to the cathode where it is measured
42
What are the two points of calibration for transcutaneous tcPO2 sensors?
A drop of solution with no free O2
Ambient air
43
Describe the accuracy of tcPO2 and tcPCO2 in neonates
tcPO2 is often similar
TcPCO2 is often higher than PaCO2
44
What piece of machinery is use in tcPO2 detector?
Polarographic clark electrode
Silver anode
Semipermeable membrane
Heating element
45
What piece of ,machinery is is used in a tcPO2?
Severinghaus electrode
pH electrode
Reference electrode
Teflon membrane
Heating element
46
Describe how the tcPCO2 operates
Skin is heated to 108-113 degrees fahrenheit
Arterial blood supply is increased to dermal capillary
CO2 diffuses across the sensor membrane interacting with electrolyte solution
Hydrogen and bicarb ions are formed
CO2 is determined
47
What mathematical equation is used to determine CO2 in a tcPCO2 sensor
Henderson-hasselbalch equation
48
What kind of calibration is used for tcPCO2 sensors?
One and Two point calibrations
49
Describe 1 point calibration for tcPCO2 sensors
Expose electrode surface to 5% CO2 gas for several minutes
50
How often is one point calibration uses in tcPCO2 sensors?
Every 4 hours during continuous use
After any period of disuse
51
What is the acceptable difference in calibrations when performing a 1 point calibration on tcPCO2 sensors?
2 mmHg
52
Describe 2 point calibration for tcPCO2 sensors
Expose electrode surface to 5% and 10% CO2 gas for several minutes
53
When should 2 point calibrations be performed on tcPCO2 sensors?
At least once during a 25 hour cycle of continuous use
After membrane and electrolyte change
Whenever in doubt of clinical reliability
54
What can cause discrepancies in tcPCO2 and tcO2 monitors?
Skin oxygenation consumption
Heating of the underlying skin
Impaired peripheral circulation
Shock
Very low core temp
54
What should calibration readings be within when performing a 2 point calibration on a tcPCO2 sensors
Should be within 4 mmHg
55
What might affect the accuracy of transcutaneous oxygen and carbon dioxide monitors?
Ambient air temp
Humidity
Barometric pressure
Membrane thickness
Rate of oxygen and CO2 diffusion across electrode
Polarization voltage of the electrodes
56
Compare readings between arterial and transcutaneous readings
tcPO2 is like PO2
tcPCO2 is higher than PCO2
57
What are the hazards of transcutaneous monitors?
Burns
58
What can affect the response time of transcutaneous monitoring?
Material and size of cathode
pH of the electrolyte used in the sensor
Membrane potential
59
What physiologic factors can cause differences between transcutaneous sensors and ABGs?
Skin permeability
Unusual capillary configurations
Temp differences
Impaired peripheral circulation
60
What are the hazards of transcutaneous monitors?
61
What can apnea monitors track?
Apnea (duh)
Heart rate
Oxygen saturation
62
What patients are apnea monitors most frequently used on?
Premature babies
Patients at risk for apnea (DUH)
63
Describe the detection methods for apnea monitors
Impedance pneumography
Thermistors
Infrared CO2 sensors
Mattress pressure pads
Pneumatic abdominal sensors
64
How does impedance pneumography work?
Detects changes in electrical impedance
65
How do thermistors, proximal airway pressure sensors and carbon dioxide sensors work?
Directly monitor airflow
66
How do pneumatic abdominal sensors work?
Changes in pressure with expansion or contraction
67
How are apnea monitors calibrated?
Not frequently or extensively calibrated
Calibrated via functional self test
67
What are the standard features of apnea monitors?
Timers
Visual and audible alarms
Heart rate monitors
SpO2 monitors
68
What can cause issues with apnea monitors?
Artifacts from heart activity
Patient movement
Home appliances
69
Indirect calorimetry can be used for what?
Understand metabolic diseases
Type II diabetes
Heart disease
Lung disease
70
What can indirect calorimetry be used for that is not disease related
Athletes to determine caloric needs
Nutritionists to determine caloric needs
71
What does indirect calorimetry measure
Inspired gas flows
Expired gas flows
Volumes and concentrations of oxygen and CO2
72
What patients can indirect calorimetry be used on?
Ventilated patients
Spontaneous breathing patients
73
T/F: indirect calorimetry requires a closed circuit method
False. Can be done in a closed or open circuit method
74
Describe the theory behind indirect calorimetry
All energy is derived from the oxidation of carbs, fats and proteins and the ratio of CO2 produced to O2 consumed (respiratory quotient) is characteristic of the fuel being burned
75
Describe open circuit indirect calorimetry
Concentrations and volumes of inspired and expired O2 and CO2 are measured to determine O2 consumption and CO2 production
76
What is required to ensure the accuracy of indirect calorimetry?
Stable FiO2
Leak free system
77
What does calibration of indirect calorimetry involve?
Calibration of gas analyzers, pressure transducers and flow sensors
77
When is calibration of indirect calorimetry performed?
Usually automatic
Once daily
78
How does closed circuit indirect calorimetry differ from open circuit?
Method for measuring o2 consumption
Uses volumetric spirometer, mix chamber, carbon dioxide analyzer and carbon dioxide absorber
79
What are the applications for an esophageal pressure catheter?
Differentiation of chest wall, lung, and respiratory system mechanics
Monitoring parenchymal lung stress
Limiting peak end inspiratory transpulmonary pressures
Monitoring vent synchrony
PEEP titration
80
Where is the esophageal pressure monitor placed?
The lower 3rd of the esophagus
81
Describe the components of an esophageal pressure catheter
Balloon tipped catheter attached to a pressure transducer
81
What is the esophageal pressure catheter used for?
Used to estimate pleural pressure
82
What are contraindications for esophageal pressure catheters?
Esophageal varices, tumors, ulcerations, diverticulitis
83
Describe the principles of operation of an esophageal pressure catheter
Air filled balloon ( 0.5-1.5 mL) placed in lower 3rd of esophagous
Proximal end is connected to pressure transducer
Pressure transducer incorporated in mechanical ventilators
84
What area of insertion is preferred for esophageal pressure monitors?
Nasal
85
What is done after an esophageal pressure monitor is inserted?
Positioning is checked via xray
86
Describe galvonic oxygen analyzers
Use galvanic or polargraphic cells
Self energizing
Sensor consists of an anode and a cathode
Contains a semipermeable membrane and electrolight
87
When should esophageal pressure monitors be replaced?
Every 29 days
88
What are the two points of calibration for oxygen analyzers?
21% and 100%
89
Describe polarographic oxygen analyzers
External electric source
Electrochemical sensor measures changes in partial pressure of O2
Contains anode and cathode
Contains electrolyte
90
What are the two types of helium analyzers?
Handheld
Incorporated into diagnostic systems (ie PFTs(
91
What does the electronic circuit of a helium analyzer measure
Measures the difference between the thermal conductivity of the gas mixture and that of a reference gas and then calculates the helium content
92
How is helium content analyzed?
Measurement is based off the high thermal conductivity of helium
93
What are the two main components of a helium analyzer?
Sensor block
Electronic circuit
94
Describe the calibration requirements of a helium analyzer
Supplied fully calibrated
Needs calibration check every 30 days
Requires very little maintenance
Sensitive to vibration
95
What is exhaled nitric oxide used for?
as a marker for the diagnosis of asthma
to monitor the response to anti-inflammatory meds
to monitor adherence to asthma medications
predict upcoming asthma exacerbations
96
How many points of of calibration do exhaled nitric oxide monitor use?
3
97
to measure the oxygen from a large volume jet neb to determine the correct FiO2, the therapist needs:
oxygen analyzer
98
What situation can change the results of pulse oximetry?
low perfusion to a digit
motion
anemia
interference from surrounding light
99
Babies who need a monitor to ensure they are breathing need a:
apnea monitor
100
What is indirect calorimetry?
a technique that measure inspired and expired gas glows, volumes, and concentrations of O2 and CO2
101
What kind of electrode does a transcutaneous CO2 monitor use?
severinhaus electrode
102
A baby that needs ventilation of PCO2 monitored would need a
transcutaneous carbon dioxide monitor
103
to determine the inspired and expired gas flow, volumes and concentrations of carbon dioxide and oxygen, what kind of test/monitor should be used?
indirect calorimetry test
104
What does and esophageal pressure catheter monitor?
estimates pleural pressure
105
What oxygen analyzer is self energizing, contains an anode and a cathode and contains a semipermeable membrane and electrolyte?
galvanic oxygen analyzer
106
Describe a polarographic analyzer
a polarographic analyzer has an electrochemical sensor to measure the partial pressure of oxygen
