EET286 – Fall 2015 follow-up 2015-12-10 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

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.

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

NFPA99 Chassis Leakage (touch) Current 1999 edition 2005 edition 2012 edition 2015 edition 10.2.6* 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).

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 0.00097 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

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

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

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

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

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

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

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)

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

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.

Where does the leakage current go?

Open ground ! Where does the leakage current go now?

chassis leakage current: Test device measuring chassis leakage current:

as defined by the IEC standard 60601-1: “Applied Part” of medical equipment as defined by the IEC standard 60601-1: 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)]

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

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

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.

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

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

Pressure waveforms during insertion of the Swan-Ganz catheter:

Most used:

Manual determination of NIBP blood pressure :

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

Pressure pulsations during oscillometry:

non-invasive blood pressure monitor

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)

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.

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)

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