Chapter 3 MI Introduction to Patient Monitoring System Flashcards
What is the purpose of patient monitoring?
To have a quantitative assessment of the patients important physiological variables during critical conditions of his biological functions
What are some desired design features of a Patient Monitoring System? (3 examples)
1) Mobility
2) Ease of use
3) Effortless patient data transfer
What are the 6 patient monitoring variables?
1) Body Temperature
2) Heart Rate
3) Blood Pressure
4) Respiration Rate
5) Oxygen Saturation
6) ECG
What is the normal core temperature range?
36.5 Degree Celsius to 37.5 Degree Celsius
Will body temperature increase when waking up, by how much?
Yes, by 0.5 Degree Celsius
Does anesthesia lower body temperature, by how much?
Yes, by 1 Degree Celsius
What are the 4 modes of body heat loss?
1) Radiation
2) Convection and conduction of air
3) Evaporation of sweat
4) Evaporation of water through breathing
What are the 4 Temperature Measurement Methods?
1) Invasive or Non- Invasive
2) Contact or Non Contact
3) Direct or Indirect
(Direct means convert temperature to electricity, while Indirect means curve or algorithm)
4) 1-D and n-D
What is an Invasive way to measure temperature?
May require needle-type or a catheter-type (rectum and blood vessel)
What is an Semi-Invasive way to measure temperature?
Normal clinical thermometer (through the mouth)
What is an Non-Invasive way to measure temperature?
Normal clinical thermometer can be used, including infra-red radiation types (forehead, ear canal)
Heart rate measurement can come from which 2 types of reading?
1) ECG reading
2) Pulse rate reading
What is the typical range of heart rate measurement?
0 - 250 beats/min
What is the normal heart rate range?
60 - 100 BPM
What is blood pressure?
It is the force of the body’s blood pushing against the walls of your blood vessel
What is systolic pressure?
It is the pressure when your heart contracts
What is diastolic pressure?
It is the pressure when your heart rests between beats
What is a Healthy BP reading?
120/80 mmHg or lower (millimetres of mercury)
Can Diastolic BP change with age?
Yes, diastolic blood pressure can increase with age as a result of stiffening arteries
What are the 3 Indirect Methods to measure BP?
1) Auscultatory (using Sound)
2) Oscillometric (using Vibration)
3) Ultrasonic (using Waves)
What is auscultatory method?
1) Occlusive cuff is inflated until the pressure is above systolic pressure then slowly bled off
2) When the systolic peaks are higher than the occlusive pressure, the blood spurts under the cuff
3) Audible sounds (Korotkoff sounds) generated by the flow of blood and vibrations of the vessel under the cuff are heard through a stethoscope
4) The manometer pressure at the first detection of the pulse indicates systolic pressure
5) When the sound can no longer be heard, the manometer pressure indicates diastolic pressure
6) This depends on the hearing acuity of the user, as well as a relatively quiet environment
What is oscillometric method?
1) Compression cuff is inflated above systolic pressure and slowly deflated
2) Systolic pressure is detected where there is a transition from small amplitude oscillations to increasing cuff-pressure amplitude
3) Algorithmic methods are used to predict diastolic pressure
What is ultrasonic method?
1) Compression cuff is placed over the transmitting and receiving crystals (at 8MHz)
2) Opening and closing of blood vessel are detected as the applied pressure is varied
What are the 2 Direct Methods to measure BP?
1) Extravascular Sensor (Sensor outside of body)
2) Intravascular Sensor (Sensor inside body usually tip of needle)
What is extravascular sensor?
A sensor outside of body
(Typically a catheter that is connected to an external pressure sensor; inserted surgically)
What is intravascular sensor?
A sensor inside the body, usually tip of needle
(The sensor is incorporated into the catheter tip; inserted surgically)
What is the technique to obtain heart rate from ECG?
Heart rate meters usually work on the basis of converting each R wave of the ECG into a pulse of fixed amplitude and duration. Afterwards, it will determine the average rate from those pulses.
What is the technique to obtain pulse rate from oximeter?
The pulse oximeter typically uses photoelectric method (reflectance or transmittance) to pick up the pulse rate
What is Respiration Rate?
It is the number of breaths a person takes in a minute (usually at rest)
What is the normal range for Respiration Rate?
12 - 25 breaths per minute
What is the 5 Measurement Methods for Respiration Rate?
1) Displacement Method
2) Thermistor Method
3) Impedance Pneumography
4) CO2 Method
5) Apnea Detectors
What is Oxygen Saturation?
It is the measurement of how much oxygen is bounded to your blood
When/why do we need to know the level of blood oxygen saturation? (5 examples)
1) During or after procedures that uses sedation
2) To see how well lung medicines are working
3) To check a person’s ability to handle increase activity levels
4) To see if ventilator is needed to help to breathe
5) To check if there are moments when breathing stop during sleep
How do we measure Oxygen Saturation? (3 examples)
1) Pulse Oximetry (most common way to measure)
2) Skin Reflectance Oximeter
3) Intravascular Oximeter
What does P wave represent?
Contraction/Depolarization of the Atria
What does the QRS Complex represent?
Contraction/Depolarization of the Ventricles
What Does the T wave Represent?
The Relaxation/Repolarization of the Ventricles
Where does the repolarization of the atria occur?
During the QRS complex, which masks it on the ECG
What are common ECG abnormalities? (5 examples)
- Second-degree block
- Atrial fibrillation
- Ventricular tachycardia
- Ventricular fibrillation
- Third-degree block
How does Second Degree block look like?
From diagram, 50% of P wave no QRS and 50% of P wave got QRS
How does Atrial Fibrillation look like?
From diagram, there is no clear P wave while QRS got more QRS wave
How does Ventricular Tachycardia look like?
From diagram, during the S phase of QRS, it will have a very big dip down
What Does Ventricular Fibrillation look like?
From diagram, it just looks like noise, no clear wave
How Does Third-Degree Block look like?
From diagram, it looks like a flat line but sometimes there is still a small signal
How many electrodes are there in ECG?
(Chest how much? Limb how much?)
10 Electrodes
6 Chest electrodes
4 Limb electrodes
What are the 6 Frontal Leads?
1) I
2) II
3) III
4) aVR (augmented unipolar Vector Right leg)
5) aVL (augmented unipolar Vector Left leg)
6) aVF (augmented unipolar Vector Foot)
What are the 6 Transverse Leads?
1) V1
2) V2
3) V3
4) V4
5) V5
6) V6
How many of the 12 leads are bipolar and what are they?
3 leads (bipolar)
1) I Lead
2) II Lead
3) III Lead
Because no fix reference point
Lead I, 2 electrodes start from where and end at where?
Starts From Left Arm (+) ends at Right arm (-)
Lead II, 2 electrodes start from where and end at where?
Start from Left Leg (+) to Right Arm (-)
Lead III, 2 electrodes start from where and end at where?
Start from Left Leg (+) to Left Arm (-)
What is Eindhoven’s Triangle?
The vectors of leads I, II, and III where I - II + III = 0
(Basically, KVL also known as Kirchhoff’s Voltage Law)
Suggest situations for continuous observation of ECG and heart rate (3 examples)
- During anesthesia and recovery from anesthesia
- During danger period following myocardial-infarction
- During labour
In cardiac monitor, briefly describe functions of
a) Pre-amplifier
b) Isolation circuit
c) Amplifier
d) ADC
e) Alarm indicator
a) Pre-amplifier - amplifies ECG signals and improve signal-to-noise ratio
b) Isolation circuit - blocks current from power line
c) Amplifier - amplifies ECG signals to appropriate level for recording (include band-pass filter)
d) ADC - digitizes ECG signals to facilitate storage, display and transmission
e) Alarm - warns of high and low heart rates
What are the common artefacts in ECG? (3 examples)
1) Power line interference
2) Baseline shift
3) Muscle tremor
How to reduce the effects of power line interference?
Noise rejection circuitry in amplifiers, shielding, earthing
How to reduce the effects of baseline shift?
Ensure patient is relaxed and electrodes properly attached with electrode gel
How to reduce the effects of muscle tremor?
Can be partially solved by attaching electrodes to chest instead of limbs
