OBJECTIVE Without reference, identify basic facts about the clinical applications of pulse oximeters...

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OBJECTIVEWithout reference, identify basic facts about

the clinical applications of pulse oximeters with at least 70 percent accuracy.

Pulse Oximeters

Purpose Provides continuous, noninvasive

monitoring of patient oxygenation Provides rapid indication of a patient’s

changing level of oxygenation

Pulse Oximeters

Determines arterial blood oxygen saturation (SpO2) using spectrophotometric oximetry principles• Spectrophotometric Oximetry is the measurement of blood

oxygen concentration using an instrument that makes measurements based on the comparison of light being output to the amount received. The more light received the less that was absorbed by the blood.

Determines pulse rate using plethysmographic techniques

Pulse Oximeters (Continued)

Principles Differential light absorption is used to

determine the percent of oxygen saturation of hemoglobin in arterial blood

Hemoglobin - an iron-containing compound found in red blood cells that carries oxygen from the lungs to the body tissues Two different wavelengths of light

Red Infrared

Emitted from a probe Passes through a pulsating arterial bed

Fingertip Earlobe Forehead

To a photodetector

• Light absorption Absorption characteristics »Oxygenated hemoglobin absorbs less

than deoxygenated hemoglobin at the red wavelength

»They are more similar at the infrared wavelength

Each pulse of arterial blood causes small arteries and arterioles to expand and contract, this varies the amount of light absorbed by the arterial blood

A portion of the passing light is absorbed by tissue constituents »Venous blood »Muscle »Cartilage »Bone

The absorption due to these constituents is constant allowing the microprocessor to eliminate them from the calculations

Plethysmographic technique Plethysmogram corresponds to the

patient's pulse waveform This signal is used to calculate the

patient's pulse rate, and is determined from the peaks of the arterial blood waveforms

• Sensor probes Transmittance probes - light from each

LED is passed through the measurement site to a single photodetector on the opposite side

Reflectance probes - light scattered along the tissue surface is collected by a photodetector adjacent to the LED

In both probes, LED's alternately pulse on and off

This allows differentiation between red and infrared light at the photodetector

the clinical applications of patient monitoring systems with at least 70 percent

accuracy.

Patient Monitoring Systems

Intended Purpose -To watch or monitor a patient's vital signs and display waveforms and/or numerical data

Vital signs Heart rate and ECG

When the heart contracts an electrical signal can be detected by electrodes placed on the patient's chest and extremities

This electrical signal can be plotted as a function of time, and the resultant waveform is referred to as an electrocardiogram (ECG)

• Pulse • Temperature • Blood pressure

Systolic - the peak blood pressure felt in the circulatory system

Diastolic - the resting pressure of heart Mean - average of the systolic and

diastolic

Patient Monitoring Systems (Continued)

Respiration Arterial O2 saturation Cardiac Output Airway CO2 Concentration

The medical and nursing staff analyze these physiological parameters To reveal changes in patient's condition To determine proper treatment

Typical locations Acute care units

Intensive care units Cardiac care units

Surgery and recovery units

Description of Monitoring Systems Bedside monitor mainframe Has a display and possibly a printer Can be switched with any bedside

monitor Has ports for different modules or

different modules are built in

Modules of a bedside monitor ECG module

Amplification of the cardiac signal is performed within the ECG module

Displays electrical activity of the heart by waveform presentation on CRT

Can display oHeart rate - determined from the R to R

interval oHeart irregularities

Heart rate alarms Tachycardia - heart rate is too fast Bradycardia - heart rate is too slow

Blood pressure module To monitor patients when fluids are

being lost; in burn victims or major surgery

To monitor patients when fluids are gained; during infusions of blood or other fluids

To detect hypotension (low blood pressure) which can lead to vascular collapses because of hypovolemia (low blood volume)

To detect hypertension (high blood pressure) which can overload the heart because of hypervolemia (high blood volume)

Temperature module (body temperature) Usually measured by means of a

thermistor probe Probe is inserted in mouth, armpit, or

rectum

Respiration module Methods »Most common - impedance

pneumography - measurement of the change of impedance across patient's chest during respiration

Pressure sensitive capsules placed on abdomen to detect body movement

Thermistor near mouth or nose to measure change in temperature between inhaled and exhaled breaths

May also include an apnea alarm

Carbon dioxide (CO2) module • Measures CO2 concentration at the end

of an exhaled breath • Two types

Capnograph »Measures the increase and decrease

in CO2 during each inspiratory / expiratory cycle

»Displays both CO2 waveform and numerical data

Capnometer Continuously measures CO2 Displays only numerical data When connected to a patient monitor,

becomes a capnograph

Pulse oximeter module Noninvasive and continuous means of

monitoring percent of O2 saturation (SaO2) of arterial blood

Reduces the need for arterial puncture and blood gas analysis

Physiological monitors are often equipped with 2 types of alarms System faults

Loose electrodes Defective electrodes

Physiological parameters have exceeded the limits set by the operator

the clinical applications of electrocardiograph units with at least 70

percent accuracy.

Electrocardiograph

Intended Purpose To detect the electrical activity of the

heart and produce an electrocardiogram (ECG) which is a graphic record of voltage versus time

To diagnose cardiac abnormalities To monitor patient's response to drug

therapy

Electrocardiograph Units

To revel major changes in heart rate and cardiac rhythm (ECG disturbances) Pericarditis - inflammation of the sac

containing the heart Atria and ventricular hypertrophy -

enlargement f the walls due to obstruction

Myocardial infarctions - coagulation in the muscular tissue of the heart resulting from obstruction of circulation

Electrocardiograph Units (Continued)

Ventricular fibrillation Asystole Electrolyte concentrations and acid base

balance Increased metabolic activity Drug reactions Hypoxemia - low oxygen content in the

blood Hypothermia - low body temperature

ECG monitors typically measure and display up to three physiological parameters Electrocardiogram (ECG) Heart rate Body temperature or respiration

Elements of the ECG P-wave - represents depolarization of both

atria Begins with electrical impulse from the

SA node Impulse spreads in wave-like fashion,

stimulating both atria Both atria depolarize (contract) and

produce electrical activity

PR Segment Electrical impulse from atria passes to

the AV node There is a 1/10 second pause allowing

blood to enter the ventricles The AV node is depolarized Duration - .12 - 2.0 seconds Measures from the onset of the P-wave to

the onset of the QRS complex

QRS complex Represents the electrical impulse as it

travels from the bundle of HIS into the bundle branches into the Purkinje fibers and into the myocardial cells (causing ventricular contraction)

The depolarization of the ventricles Duration - .08 - .12 seconds

Consists of: Q-wave

First down stroke of the QRS complex Not always present

R-Wave - first upward deflection of the QRS complex

S-Wave - first downward stroke after the R-wave

ST segment Used to identify myocardial infarctions Serves as the isoelectric line from which

to measure the amplitudes of other waveforms

J-point - junction between the QRS complex and the ST segment

T-wave - represents the repolarization of the ventricles

Principles of Operation The heart rate is determined by the R to R

interval of successive QRS waves Electrocardiographs record small voltages

(about 1mv) that appear on the skins surface as a result of cardiac activity by using various electrode configurations discussed earlier

Multichannel electrocardiographs Operate similarly to single channel units

in that the user selects certain similar functions:Automatic or manual lead switching Signal sensitivity Chart speed

Unlike signal channel units, multichannel units have some advantages:Record 3 or more leads simultaneously Tracings can be held in memory Tracings are printed out in a one-page

format

Modes Manual mode »User selects three leads to be

recorded »Unit traces signal from these leads

until others are selected

Automatic mode »Each standard 12 leads are recorded

for a preset time period »Switching from one lead to another

occurs automatically »Some units can be programmed to

record tracings from any lead sequence

Units with integral timers and selectable chart speeds can also be programmed for »Stress testing »Trending »Rhythm monitoring

Semi-automatic mode »Recorder scans through first lead

Semi-automatic mode » Recorder scans through first lead group »Then switches to observe modeoAllows user to preview next lead group

for signal quality before recording oUser restarts recording of next group

manually• Lead hold feature

Overrides programmed timer Allowing longer recording time for a

particular lead

Sensitivity setting User selectable Determines size of the recorded ECG

waveformECG signals that become too large and

produce a waveform that goes over scale (arrhythmic beat) »Most units will automatically switch to

lower sensitivity setting immediately

Other units allow user to choose between recording »Affected channel at lower sensitivity »All channels at lower sensitivity »Waveform as is, followed by re-

recording at lower sensitivity

Frequency response Factory-set to detect ECG signals

between 0.05 and 100 Hz for diagnostic purposes

Electrical interference also occurs within this range producing artifacts by recording »Muscle movement »Line power frequency

To reduce such interference, notch filters can be selected to block these frequencies »Because filters limit frequency

response, they can affect diagnoses based on certain details (amplitude)

»Therefore, they are not usually used for diagnostic recording

ECG tracings Single-channel units require cutting

and pasting to achieve standard format Mutichannel electrocardiographs

require less preparation time - 3 leads are recorded simultaneously

In some mutichannel units, no cutting or pasting is necessary

»ECG signals from each lead are stored in memory

»Then traced all at once on a single page

»Therefore, all 12 ECG tracings are representations of the heart's electrical activity from same heart beat

Formatting options One-page formatting Formatting according to number of

pages programmed

Formatting according to number of heart beats recorded in each lead group

Formatting according to number of seconds for overall recording

Automatic formatting saves time but an atypical waveform may be missed

Some units are capable of producing multiple copies of recent ECGs

Data which can be printed at the top of ECG recordings Patient data (entered by alphanumeric

keyboard if available) Time Lead identifiers Heart rate

Recording parameters »Sensitivity setting »Chart speed »Filtered mode

Options Heart rate LED or LCD displays

Alarms »Tachycardia »Artifacts »Loose electrodes »Out-of-paper »System fault (leads/electrodes)»Automatic recording

Capability of storing rhythm strips for later retrieval

Ability to extend recording time if arrhythmia is detected

ECG report editing capability "Freeze" capability »ECG will be held and displayed

indefinitely »The current trace will be lost or

transferred to another channel (printer)

"Memory delay" feature - the last few seconds of the trace prior to an alarm will be lost or transferred to another channel or printer

Some store, compute, and display trends in data through the use of a microprocessor »Trend plot is a graph of a physiological

parameter over a period of time »Heart rate trend is an example

Where Multichannel Electrocardiographs are Found

Doctor's office Flight medicine clinics Physical exams and standards clinics Intensive care units Coronary care units Emergency rooms Cardiopulmonary labs Special care units

OBJECTIVEWithout reference, identify basic facts about the clinical applications of defibrillators with

at least 70 percent accuracy.

Defibrillators

Terms and Definitions Arrest - cessation of the electrical activity of

the heart Atrial flutter - very rapid (250-150/min)

electrical discharge and contraction of the upper chambers (atria) of the heart

Cardiogenic shock - shock resulting from the diminishment of cardiac output

Fibrillation - irregular, totally disorganized electrical activity of the atria or ventricles or both

Defibrillators (Continued)

Defibrillation - electrical termination of fibrillation

Cardioversion - the restoration of the sinus rhythm by electrical shock

Synchronous - occurring at the same time Stored energy - the energy stored within

the defibrillator by the capacitor

Joule - a unit of work; the energy expended by 1 amp flowing for 1 second through 1 ohm of resistance Also called a watt second The unit of calibration for the output of a

defibrillator

Intended Purpose To apply controlled monophasic (single

phase) or biphasic (two phase) DC defibrillating pulse to the heart Monophasic

One pulse of electricity One direction of current flow between

the paddles High amounts of energy needed

Biphasic • Current reverses itself • Two directions of current flow • Uses smaller amounts of energy • Can compensate for differences in

patient impedance Chest size Tissue density

Sync mode To perform elective cardioversion Uses the patient's generated R-wave as a

timing reference Most defibrillators also monitor the ECG

signal To verify fibrillation To verify effectiveness of treatment

Patient signals can be picked up by the external paddles which are transcutaneous leads

Paddle Types Standard adult external Anterior/posterior Internal Pediatric Neonatal (newborn) Disposable

Modes of Operation External emergency defibrillation

Discharge into the patient by pressing the 2 discharge buttons (one on each handle) simultaneously

2,000 to 4,000 volt shock For less than 20 msec Using gels and pastes to improve

conductivity between paddles and chest

AHA ( American Heart Association) Studies indicate that about 98% of patients

can be defibrillated with 300 joules or less Recommends not exceeding 360 joules

delivered to the patient Internal defibrillation

Energy is delivered directly to the exposed heart

All defibrillators are designed to limit the output energy to 50 joules to prevent injury to the heart muscle

• Paddles are small (50 mm in dia.) and able to withstand sterilization between uses

Synchronized cardio version (Sync Mode) • Uses a discharge of 25-100 joules • Used to correct certain arrhythmias

Ventricular tachycardia Atrial flutter

• Sync marker will show up on the defibrillator monitor on the R-wave

The shock is delivered On the first down stroke of the R-wave

detected after both paddle discharge buttons are pressed

Must occur within 30 msec of the R-wave

Timing is critical because discharge during the T-wave could cause fibrillation

OBJECTIVEWithout reference, identify at least four out of

six basic facts about the clinical applications of invasive and noninvasive blood pressure

monitors.

Invasive and Nonivasive Blood Pressure Monitors

Purpose The presence of an ECG signal does not

assure effective pumping of blood Automatic electronic sphygmomanometers

noninvasively measure and display a patient's arterial blood pressure

Invasive and Nonivasive Blood Pressure Monitors (Continued)

Terms and Definitions Systolic pressure - the highest arterial

pressure of the blood Diastolic Pressure - the lowest arterial

pressure of the blood Mean - midway or an average of the

systolic and diastolic pressures Pulse pressure - the difference between

the systolic and diastolic pressures

Korotkoff sounds - sounds heard through the stethoscope as the blood flow changes

Hypotension - low blood pressure Hypertension - high blood pressure Hypovolemia - inadequate blood volume Hypervolemia - excessive blood volume Noninvasive - uses a cuff Invasive - uses a catheter and puts patient

at a higher risk of infection or emboli

Normal pressure - 120/80 mmHg expressed as systolic over diastolic pressures

Principles of Blood Pressure Left ventricle of heart contracts • Blood is forced into arteries • Creates a pressure increase, peak of

which is called systolic pressure

Ventricles then relax Pressure in the arteries decrease as

blood leaves arteries and enters capillaries

Lowest point the pressure reaches before the next ventricular contraction represents the diastolic pressure

Pressure values are recorded in millimeters of mercury (mmHg)

Noninvasive Method Peripheral blood flow sounds were

correlated to systolic and diastolic pressures by Nicolai Korotkoff in 1905

Uses a cuff wrapped around patient's arm and a stethoscope

Cuff is inflated to pressure greater than systolic pressure Patient's artery closes Blood flow stops

Cuff pressure is gradually lowered, pressure falls below systolic pressure but higher than diastolic pressure Some blood forces its way through artery Blood flow not normal, the resulting

turbulence produce korotkoff sounds Sounds persist until cuff pressure falls

below the diastolic pressure and blood flow returns to normal

Techniques for Automatic Measurement Auscultatory Same principles as

sphygmomanometers, detection of korotkoff sounds Pressures at which korotkoff sounds

first begin mark the systolic pressure Pressures at which sounds disappear

marks the diastolic pressure Cuff with transducer wrapped around

patient's arm

Cuff is inflated with transducer positioned against compressed artery Transducer detects korotkoff sounds Enables user to determine both systolic

and diastolic values Oscillometric Cuff is wrapped around a patient's arm

and inflated Pressure in the cuff is released

Sensor located in the monitor detects air pressure fluctuations in the cuff Due to arterial volume changes Occur because blood is pulsing through

artery, rather than flowing smoothly Pressure at which oscillations peak

correspond to mean arterial pressure (MAP)

Unit calculates the systolic and diastolic pressures from the increasing and decreasing magnitude of the oscillations

Differential sensor Cuff with dual-head sensor inflates

around a patient's arm Cuff pressure is released

Sensor against artery detects korotkoff sounds, oscillometric pressures and artifact signals

Sensor against the cuff (air bladder) detects only oscillometric sounds and artifact signals

The monitor subtracts the two signals leaving only the korotkoff sounds

Process should remove some of the unwanted interference signals

Light-emitting diode (LED) Cuff bladder - slipped over patient's

finger or thumb

Cuff is inflated stepwise under microprocessor control Signals from optical sensor determine

mean arterial pressure which is sufficient enough to permit the artery to remain open

Procedure repeated several times in first minute until volume of finger under cuff is stabilized »Once stabilized, unit is calibrated to

patient

» Calibration procedure takes place every minute in some units

Changes in blood volume causes the optical sensor to send signals to an electropnuematic servo-controlled valve Increases and decreases the cuff pressure A transducer detects the cuff pressure and

produces a corresponding electrical signal Arterial pressure waveform can be displayed

on a monitor or sent to a printer

Advantages of Noninvasive Low risk to patient compared to invasive Simplicity - easy to set up

Locations Emergency room Intensive care unit Surgery Recovery

the clinical applications of infusion pumps with at least 70 percent accuracy.

Infusion Pumps

Introduction to Fluid Therapy Body fluid balance depends upon • Fluid intake • Body requirements for fluids

Functioning regulatory systems • Cardiovascular system (volume and

blood pressure) • Urinary system (Kidneys) • Nervous system • Endocrine system (Hormones)

Infusion Pumps (Continued)

Electrolytes and other chemical substances which keep body fluids in balance

Disturbances in fluid balance Dehydration - insufficient body water

Causes » Inadequate fluid intake »Vomiting and diarrhea »Fever and excessive sweating

Signs and symptomsThirst Weight loss Low fluid output/concentrated urine Dry membranes in mouth and eyes

Treatment Replace fluids orally when mild Replace fluids by standard IV drip when

severe

Edema - accumulation of excess fluid in body tissue Causes

Heart failure or vessel obstruction Protein loss (starvation, burns) Systemic infection/inflammation Kidney problems/renal failure

Signs and symptoms Swollen eyelids/puffy face Swollen feet and ankles Abdominal distention

Treatment Special IV fluids which pull water from

tissue into vessels Low sodium diet

• Other disturbances in fluid balance Dysfunction in almost any organ

system can affect fluid balance Fluid balance can be affected by

certain drugs - hormones, diuretics

Infusion Pumps (Continued))

Fluid Therapy By Intravenous Route IV regular and special use • Provides route for fluids when oral route

cannot be used or is not practical GI problems (obstruction, mal-

absorption)

Inability to swallow (oral surgery, unconscious patient)

Intolerance to oral fluids (nausea, vomiting)

Some medications are more effective when given by IV route (antibiotics)

Used pre- and post-operatively GI tract must be at rest for anesthesia

related safety purposes (i.e. no food) Gives emergency access to the

circulatory system during surgery for fluid replacements, blood, medication, etc

Emergency Effects of IV fluids/drugs are realized

immediately (within seconds) Gives rapid access to circulatory

system Lack of good peripheral circulation in a

shock patient causes poor absorption of IM (intramuscular) or subcutaneous injection. Therefore, IV is the method of choice

Limitation/problems of IV therapy • Requires special skill • Certain fluids/drugs cannot be given

through an IV • Complications associated with venous IV

site Infection Tissue breakdown due to drugs or

reaction of tissue with IV line Blood clots (embolism) Air embolus (air bubbles in blood stream)

Monitoring IV Therapy Drip rate - measured in cc/hr, is the correlation

between number of drops/minute with actual volume (cc)/hour Leaves room for error due to multiplier effect Changes due to filter clogging or kinked tube Ratio of drops/minute to cc/hr differs with

infusion sets and viscosity of liquid being infused Thicker fluids have slower drops/minute

Importance of monitoring • Assure proper amount of drug/fluid is

administered • Required to prevent too much or too little fluid

intake (edema or dehydration) Infusion Therapy

Best way to provide continuous, well controlled infusion • Controlled/preset volume • Delivery is at a constant rate • Can monitor rate, volume, or both depending on

model or style

Types Controllers

Use gravity feed Monitor the rate by counting drops/minute Control rate by pinching infusion line

Pumps - use pressure to move fluid from IV bag to the patientPeristaltic (usually not direct volumetric, but

counts drops) Piston - known volume per stroke Therefore,

rate of stroke controlled Uses - provides continuous, well controlled

administration of critical drugs/fluids when continuous levels and/or well controlled volume is required

• Children and infants who have a small body volume • Drug therapy

Antibiotics (systemic) Cardiac drugs Anticoagulants Insulin Electrolytes

• Hyperalimentation - providing the body with nutrition intravenously

Advantages of infusion pumps over standard IV methods Usually more accurate/consistent than

standard drip method Allows for better measurement of total

fluid input when this is critical (edema) Warn the staff when there are problems

like extremely high or low pressure in the IV line (occlusion or dislodged line)

Disadvantages - always be aware • Requires power, therefore can stop

running unexpectedly • If no battery backup, patient's movement

is limited • Pumps can build up extremely high

pressure in the IV line or patient

• Can be inaccurate Too little infused - insufficient Too much infused - overdose, circulatory

overload, edema, death

Only as accurate as the BMET who calibrates it!

OBJECTIVE Without reference, identify basic facts about the clinical applications of pulse oximeters...

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