1. EET286 – Fall 2015 follow-up
Four types of clinical equipment
Power Connectors
NFPA99 Chassis Leakage (touch) Current
Human Heart & Cardiac Cycle
Wiggers diagram
Pressure Conversions
Common Electronic Component Abbreviations
Quiz #2 recap
Quiz #3 recap

2. Four types of clinical equipment
Monitoring:
Detects and displays physiologic data for the purposes of clinical observation.
Diagnostic:
Detects, displays, and records physiologic data in order to confirm or rule out a disorder or disease.
Therapeutic:
Applies treatment in the form of energy or medication in order to treat a disorder or disease.
Assistive:
Used as an accessory to facilitate a medical or surgical procedure.

3. Power Connectors plug: male connector, furthest away from power source
outlet or receptacle: female connector providing power
NEMA: (U.S.) National Electrical Manufacturers Association
IEC: International Electrotechnical Commission
NEMA wire colors:
Hot – Black Neutral – White Ground – Green
IEC wire colors:
Hot – Brown Neutral – Blue Ground Green/Yellow
Screw colors on some connectors:
Hot – Gold Neutral – Silver Ground – Green
HOT (L1) Neutral (L2) Ground (earth)
NEMA colors: Black White Green
IEC colors: Brown Blue Green/Yellow
connectors: Gold Silver Green

4. NFPA99 Chassis Leakage (touch) Current
1999 edition
2005 edition
2012 edition
2015 edition * Touch Current – Portable Equipment. The touch current for cord- connected equipment shall not exceed 500 uA with normal polarity and the ground wire disconnected (if a ground wire is provided).

7. Pressure Conversions Most useful conversions in bold 51.7 1.36 14.7
PSI
KiloPascal
cm of H2O
mm of Hg
atmosphere
millibar
1 PSI = 1
6.89
70.3
51.7
0.068
68.9
1 KiloPascal =
0.145
10.19
7.5
0.0098 10
1 cm of H2O =
0.014
0.1
0.735
1 mm of Hg =
0.019
0.133
1.36
0.0013
1.33
1 atmosphere =
14.7
101
1033
760
1013
1 millibar =
0.0147
1.02
0.75
0.0009
Most useful conversions in bold

8. Manometers, two styles; Pressure measured as a column of mercury:
closed end (contains vacuum)
measures atmospheric pressure
760 mmHg ‘normal’
higher atmospheric pressure =
higher number
(pressure in outer space vacuum
would be 0 mmHg)
open end (contains ambient
air pressure)
measures applied pressure
0 mmHg is ‘unpressurized’ state
higher applied pressure =
higher number

9. Common Electronic Component Abbreviations (rev 2015-12-01)
(silk screened on circuit boards and printed on schematics) technical term is "reference designators"
B battery
BR bridge rectifier
BT battery
C capacitor
CB circuit breaker
CR diode
CT center tap of transformer
D diode
F fuse
IC integrated circuit (chip)
J jack or jumper
K relay
L coil or inductor
LED light emitting diode
M motor
Q transistor
R resistor
S switch
SW switch
T terminal
T transformer
TP test point
U integrated circuit (chip)
VR voltage regulator
XTAL crystal

10. ECG trace and display
Calibration (y axis):
10 mm = 1 mV
Speed (x axis):
25mm = 1 Second
| mm (1 milliVolt) |
| mm (1 Second) |

11. Pacemaker Modes: Asynchronous: provides pulses at a fixed rate
Demand (or ‘Synchronous’): provides pulses when the heart fails to beat
Rate-Modulated: provides pulses based on the
heart’s current activity

12. Defibs for Cardioversion
The use of a small energy pulse from a defibrillator to convert an non-lethal arrhythmia (eg atrial flutter) to a normal sinus rhythm
Delivers a pulse about 30ms after the peak of the R-wave, synchronized by the defibrillator
Modern units can discriminate the R-wave from the T-wave or noise spikes

13. Timing of cardioversion pulse
Do NOT cardiovert across the T-wave !

14. Linear power supply (2) (3) (4) (5) Line in (not shown here)
Transform (only the output is shown here)
Rectify (usually a 4-diode bridge)
Filter (usually a big cap & a small cap)
Regulate (often with 78xx & 79xx ICs on heat sinks)
Linear power supply
(2) (3) (4) (5)

15. from Electrical Safety presentation (class 6) CORRECTED:
(per NFPA-99, 2012 edition)
Resistance of Ground wire of power cord: 500 milliOhms (500mΩ or .5Ω)
Leakage current at the chassis: NC (normal condition) 100 microAmps (100 μA)
SFC (Single Fault Condition, e.g. open ground) 500 microAmps (500 μA)
Leakage current for any one patient contact lead to ground:
10 μA with ground closed, 50 μA with ground open.
Leakage current for each patient contact lead to any other lead:
Leakage current for patient leads exposed to line voltage: 50 μA

16. Leakage current is both capacitive, caused by intrinsic
or “distributed capacitance”
Leakage current is both capacitive, caused by intrinsic
capacitance between conductors; and resistive, caused
by imperfect insulation.

17. Where does the leakage current go?

18. Open ground !
Where does the leakage current go now?

19. chassis leakage current:
Test device measuring
chassis leakage current:

20. as defined by the IEC standard 60601-1:
“Applied Part” of medical equipment
as defined by the IEC standard :
Type B: Applied parts that are generally not conductive and can be immediately released from the patient. May be grounded.
eg: Non-invasive BP monitors [think: Body]
Type BF: Devices that have direct contact with the patient, or parts that have long term contact with the patient.
eg: ECG monitors [think: Body, Floating (ground)]
Type CF: Applied parts that have direct contact with the heart.
eg: Invasive pressure monitors, defib paddles
[think: Cardiac Floating (ground)]

21. ONE of these ratings should be present on a medical device
If ‘Defib Proof’, ONE of these

22. Troubleshooting invasive BP lines:
Almost
ideal
Air bubbles
in the line
Line is
partially occluded

23. Damping in any oscillating system:
Damping is an effect on any oscillating system that reduces or restricts its oscillations. In a mechanical system, damping is produced by drag in the system. In a fluid system, damping is caused by viscosity. In an electronic system, damping is caused by impedance.
Undamped:
The system oscillates at its natural resonant frequency.
Critically damped:
When disturbed, the system returns to equilibrium quickly, without oscillation.
Overdamped:
When disturbed, the system returns to equilibrium without oscillating.
Underdamped:
When disturbed, the system oscillates, but the amplitude decreases to zero.

24. Swan-Ganz catheter (in ‘right’ heart)
Starts here Ends up ‘wedged’ here or here

25. Swan-Ganz Catheter –
From the Right Atrium through the Right Ventricle, into the Pulmonary Artery

26. Pressure waveforms during insertion of the Swan-Ganz catheter:

27. Most used:

28. Manual determination of NIBP blood pressure :

29. NIBP Blood pressure determination by oscillometry
i.e. the automated electronic method:

30. Pressure pulsations during oscillometry:

31. non-invasive blood pressure monitor

32. Quiz #3 recap R L #1: Intra-aortic balloon pump (IABP) is inserted
into descending AORTA (output of LEFT heart)
#3: IABP is typically used for 1-2 days
#6: Capnography is measurement of CO2.
Measured by how much IR (infrared) light is
absorbed by the gas sample. R L
(from body)
(TO body)
(to lung)
(to lung)
(from lung)
(from lung)
(from body)

33. Question #7:
Deep breath
(or sigh)
normal breathing
exhaling as much as you can
this much air always stays in your lungs
note: TLC is often shown as 6 liters, which is normal for a 75 kg (165 #) person.
80 ml per kg of body weight (as shown here) is more accurate.

34. Pressure-Volume-Flow (X axis for these is time)
Question #14: Flow-Volume Loop (time is shown as a counter-clockwise loop):
Pressure-Volume-Flow
Diagrams
(X axis for these is time)
exhale
note: Residual Volume is shown on the right side
(still part of Total Lung Capacity – 6 liters)
inhale
PEFR: Peak Expiratory Flow Rate:
measures how fast a person can
exhale (breathe out).
PIFR: Peak Inspiratory Flow Rate FVC: Functional Vital Capacity (same as VC)

35. Respiratory Gasses Blood Components
Inspired (inhaled) air: N2 79% O2 21%
Expired (exhaled) air: N2 79% O2 16% CO2 5%
Blood Components
Hemoglobin (hb without attached O2)
Oxyhemoglobin (hb with attached O2)
Carboxyhemoglobin (hb with attached CO, Carbon Monoxide) gives inaccurate SpO2
Methemoglobin (pron: MET-hemoglobin) cannot bind to O2 and gives inaccurate SpO2
this ratio gives SpO2 in Pulse Oximetry