BME 1008 Recap

Class III Devices

*high risk -Devices that are implanted and life-supporting/sustaining OR have potential for unreasonable risk of harm -Require FDA approval for safety BEFORE they can be marketed

Why do distal occlusions in infusions pumps often occur?

- It could be a kink in the tubing if the patient lies on it - it the patient detaches the line in their arm.

How is a medical device different than a pharmacological drug?

- Localized - primary effect NOT through pharmacological, immunological, or meteorological activity

4 ways to classify leakage in electrical devices:

- earth leakage - enclosure leakage - patient leakage - patient aux leakage

What electrical safety tests should be performed on infusion pumps?

- line voltage - ground wire resistance - chassis leakage

Polymer material examples

- nylon - silicon - polyester

How to perform ground wire resistance test?

- select ohms - with lead plugged in zero the test lead - connect probe to test points on the device

How to test for leakage current?

- select uA - connect probe to test point on device

List two ways to check a blown fuse?

- using a digital multimeter across the legs of the fuse - visually inspecting the fuse to see if the wire is broken.

Why do proximal occlusions in infusion pumps often occur?

- when the bottle side clamp is not removed - the bottle isn't vented - there is a clogged filter.

ground wire resistance should not exceed?

0.5 ohms or unless specified by facility/manufacturer

3 possible reasons there would be leakage current in a device?

1) Equipment may be built with components that have high intrinsic leakage, such as some transformers and capacitors. This leakage can find its way to patient contact surfaces. 2) Circuit design may bring current pathways or components together in such a way as to produce capacitive or inductive coupling to patient contact surfaces. 3) Components or conductors may connect with patient contact surfaces through improper design or through warping or breakage of structures.

ECG artifact examples

1. Due to leads: - bad connection (dirt, patient movement) - misplaced leads 2. Due to EMI: - other devices turned on in the room - electrical storm

How to check a fuse:

1. Inspect (leave connected if power still on): - check for broken wires or scorch marks 2. Multimeter: turn off power, use multimeter to test for continuity (no shorts) or resistance 3. Replacing: make sure to choose a fuse with the correct rating (amps)

The three modes of delivering pacemaker pulses to the heart are:

1. With a relatively large signal applied through electrodes placed on the patient's chest (requires the largest signal) 2. Through wires connected from an external device directly to the heart 3. Through wires from an implanted pacemaker device to the heart muscle. (requires the smallest signal)

According to the FDA what 3 things make a product a medical device?

1. recognized in the official National Formulary, or the United States Pharmacopoeia, or any supplement to them, 2. intended for use in the diagnosis of disease or other conditions, or in the cure, mitigation, treatment, or prevention of disease, in man or other animals, or 3. intended to affect the structure or any function of the body of man or other animals, and which does not achieve its primary intended purposes through chemical action within or on the body of man or other animals and

IEC 62353 Requirements

1. testing before initial start- up, after repair, and periodically 2. document work 3. testing includes: visual inspection, electrical measurements, leakage measurements

In general patient leads should not exceed _______ uA with the ground in tact.

10 uA

IEC 62353: leakage current for Class II medical equipment should not exceed _______ µA

100 uA

In general chassis leakage should not exceed ________ uA for portable equipment.

100 uA

IEC 62353: the protective earth resistance should not exceed _____ mW

300 mw

In general patient leads should not exceed _______ uA with the ground lifted.

50 uA

IEC 62353: leakage current for Class I medical equipment should not exceed _______ µA using the direct measurement method.

500 uA

What is the frequency of the standard U.S outlet?

60 hz

Currents greater than ____ mA* can cause ventricular fibrillation.

75 mA

How a fuse works:

A fuse is nothing more than a short length of wire designed to melt and separate in the event of excessive current.

What is Einthoven's Triangle?

An imaginary formation of three limb leads in an inversed triangle used in electrocardiography, formed with two shoulders and the pubis.

The Doppler effect

An observed change in the frequency of a wave when the source or observer is moving

What other vitals sings besides ECG are commonly monitored?

Blood Pressure, Oxygen Saturation, Temperature

Class III Device examples

Examples of this class include heart pacemakers, replacement heart valves, SCS, silicone gel-filled breast implants

Class II Devices examples

Examples of this class include insulin syringes,infusion pumps, BP gauges, diagnostic reagents, electric heating pads, electronic thermometers, power wheel chairs, & surgical drapes.

Class I Device examples

Examples of this class include toothbrushes, tongue depressors, bandages, exam gloves, eye pads, ice bags, hand-held surgical instruments.

Doppler effect example

In the case of Fetal heartbeats when the probe is placed on the mother's stomach it sends out a wave into her stomach. Once the wave enters her stomach they bounce off from the fetus's heart this then causes frequency changes in the wave. Those frequency changes are then picked up by the Doppler and converted into that weird sound you hear.

Class II Device

Medium risk

You are investigating a possible electrical short in a medical device. Removing the fuse would be difficult due to its position in the device. However you are able to measure the contact points of the fuse with your multimeter probes, there is a very small voltage drop (in mV) measured across the fuse. Is the fuse bad?

No, the fuse is not bad because it should be showing some resistance if it is working properly

OEM

Original Equipment Manufacturer

What does a proximal air in line and distal air in line sensor detect?

Proximal and distal air line sensors detect when there is an air bubble in the upstream and downstream lines of the pump.

How much voltage is required to create a hazardous current assuming average body resistance

The amount of voltage required to create a hazardous current, assuming average body resistance, is 6-30 mA.

What is the body's average resistance?

The average person has a resistance of 200,000 Ω but may vary due to weight and moisture of skin.

You are investigating an electrical short in a medical device. You measure the contact points of the fuse, there is a large voltage drop (let's say approximately 115 V), what is the likely problem?

The likely problem that has occurred is that the Neutral prong is damaged.

Two types of x-rays?

The two types of x-rays are "hard" and "soft" x-rays.

True or false. There are more incident reports on infusion pumps than any other medical device.

True.

Nuclear medicine

Uses radioactive materials either to image a patient's body or to destroy diseased cells

Which is more serious A-fib or V-fib?

V-fib

What happens to the wavelength if the frequency increases?

Wavelength decreases when frequency increases

Ventricular Fibrillation:

When the heart beats with rapid, erratic electrical impulses causing the ventricles to quiver uselessly, instead of pumping blood.

How could you check the line voltage using a multimeter? What class multimeter should you use?

You could check the line voltage using a multimeter by inserting the probes directly into the outlet. The Red lead goes to the positive (right) and the Black lead goes to the Neutral (left). After checking the voltage across the socket, then insert the Red lead into the positive again and the Black lead into the ground (round hole)

Insulator:

a material whose internal electric charges do not flow freely; very little electric current will flow through it under the influence of an electric field

Ceramic material example

aluminum oxide

Voltage:

amount of potential energy between two points on a circuit

Flow rates

amount of volume of a substance per second *ml/hr

ECG Artifacts

an abnormal signal that does not reflect electrical activity of the heart during the cardiac cycle

Soft X-rays

are greater than 0.1 nm.

Hard x-rays

are less than 0.1 nm

Why are nurses and technicians discouraged from using alcohol to prepare a patients skin for ECG electrodes?

because it can increase the impedance(resistance) of the skin

Whys is copper often used in x-ray machines as the substrate for the metal target?

because it has properties of high heat conductivity which reduces heat buildup in the target contact area.

Why is a spinning target used in X-ray tubes?

because the x-rays themselves produce quite a bit of heat so in order to keep the target from melting it is rotated to allow the entire plate to get hot instead of just one area.

Distal occlusion

blockage at the end closes to patient attachment.

Proximal occlusion

blockage in the upstream line (bottle side) that prevents the liquid from infusing to the patient.

Fuse Function:

break the circuit in case of faulty conditions so as to protect the power system equipment and auxiliaries

CAPP

capital asset protection program

Composites material example

carbon fiber

fluroscopy

continuous x-ray image for internal movement or contrast die path

Leakage current

current that flows in an unintended path

Wavelength

distance between two crests or distance between the recurring points in a wave

Current:

flow of electrical charge carriers, usually electrons

Pressure

force over an area

Class 1 device

low risk devices. *exempt from PMA and 510k

Volumes

measure amount of space occupied by a substance

Life support equipment

medical equipment that takes over the function of the human body and whose loss will cause immediate death

How do you know if a plug has a ground plug?

middle prong

frequency

number of occurrences per second (usually measured in hz)

Testing Frequency

number of times a medical device undergoes preventative maintenance

Resistance:

opposition of current

Ground Wire Resistance Testing

performed to ensure grounding is working properly by measuring resistance

Pressure formula

pressure=force/area

Atrial fibrillation

rapid, random, ineffective contractions of the atrium

Pathway of blood through the heart

right atrium -> right ventricle -> out of heart -> left atrium -> left ventricle -> out of heart Pathway of blood through the body and heart: Once the blood is in the heart it flows from the right atrium to the right ventricle and then to then into the lungs where carbon dioxide is removed and swapped out with clean oxygen. The blood then goes from the lungs into the left atrium and from there into the left ventricle where it is finally distributed throughout the whole body.

Conductors:

substance in which electrical charge carriers, usually electrons, move easily from atom to atom with the application of voltage

TSP

technical service program or partnership

The advantages to using electrical current to perform surgery are

that it not only cuts the tissue but cauterized it too which helped control bleeding as well as reduce the risk of infection. One disadvantage I could see is finding a the right current to balance between tissue cutting and not causing too much tissue damage that will significantly scar

Grounding

the grounding system is a "backup" pathway that provides an alternate route for electrical current to follow back to "ground" in the case of a problem in the wiring system.

Clinical risk

the risk associated with the clinical use of equipment

In order for liquid to flow through a tube what must happen?

there must be a difference of pressure

What is the backprime function used for?

used to infuse two drugs in a central IV through the same secondary set. This saves time and money because the line is not connected and disconnected multiple times to infuse the drugs separately.

thermography

uses infrared spectrum of light to diagnose patients

MRI

uses magnetic properties of water for 3D cross sections

Velocity formula

v=d/t

What needs to be tested on infusion pumps?

• Alarm pressure • Electrical safety • Visual Inspection • Included (blocked or pinched line) • Check the battery • Accuracy rate check • Pressure Calibration • Prime the set (no air bubbles)