Monitoring Pulse Monitoring Pulse OximetryOximetry

By the EMT-BasicBy the EMT-Basic

ObjectivesObjectives

Understand the Kansas Regulations Understand the Kansas Regulations relative to monitoring pulse oximetry relative to monitoring pulse oximetry by the EMT-Bby the EMT-B

Review the signs and symptoms of Review the signs and symptoms of respiratory compromiserespiratory compromise

Understand the importance of Understand the importance of adequate tissue perfusionadequate tissue perfusion

Define hypoxia and describe the Define hypoxia and describe the clinical signs and symptomsclinical signs and symptoms

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Describe the technology of the pulse Describe the technology of the pulse oximeteroximeter

Define normal parameters of oxygen Define normal parameters of oxygen saturationsaturation

Describe the relationship between oxygen Describe the relationship between oxygen saturation and partial pressure oxygensaturation and partial pressure oxygen

Describe the significance of the information Describe the significance of the information provided by pulse oximetryprovided by pulse oximetry

Describe monitoring pulse oximetry during Describe monitoring pulse oximetry during patient assessmentpatient assessment

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Describe the use of pulse oximetry Describe the use of pulse oximetry with pediatricswith pediatrics

Describe patient conditions that may Describe patient conditions that may affect pulse oximetry accuracyaffect pulse oximetry accuracy

Describe patient environments that Describe patient environments that may affect pulse oximetry accuracymay affect pulse oximetry accuracy

Describe the evaluation and Describe the evaluation and documentation of pulse oximetry documentation of pulse oximetry monitoringmonitoring

Kansas RegulationsKansas Regulations

Regulation 109-6-4Regulation 109-6-4 Adopts “EMT-Basic Advanced Adopts “EMT-Basic Advanced

Initiatives”Initiatives” Allows EMTs to monitor saturation of Allows EMTs to monitor saturation of

arterial oxygen levels of blood by way of arterial oxygen levels of blood by way of pulse oximetrypulse oximetry

Appropriate physician oversightAppropriate physician oversight On line medical control or written protocolsOn line medical control or written protocols

Complete a course of instructionComplete a course of instruction

Respiratory CompromiseRespiratory Compromise

Signs and SymptomsSigns and Symptoms DyspneaDyspnea Accessory muscle useAccessory muscle use Inability to speak in full sentencesInability to speak in full sentences Adventitious breath soundsAdventitious breath sounds Increased or decreased breathing ratesIncreased or decreased breathing rates Shallow breathingShallow breathing Flared nostrils or pursed lipsFlared nostrils or pursed lips

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RetractionsRetractions Upright or tripod positionUpright or tripod position Unusual anatomy changesUnusual anatomy changes

HypoxemiaHypoxemia

Decreased oxygen in arterial bloodDecreased oxygen in arterial blood Results in decreased cellular Results in decreased cellular

oxygenationoxygenation Anaerobic metabolismAnaerobic metabolism Loss of cellular energy productionLoss of cellular energy production

Hypoxemia EtiologyHypoxemia Etiology

Inadequate External RespirationInadequate External Respiration Decreased on-loading of oxygen at Decreased on-loading of oxygen at

pulmonary capillariespulmonary capillaries Inadequate Oxygen TransportInadequate Oxygen Transport

Decreased oxygen carrying capacityDecreased oxygen carrying capacity Inadequate Internal RespirationInadequate Internal Respiration

Decreased off-loading of oxygen at Decreased off-loading of oxygen at cellular capillariescellular capillaries

External RespirationExternal Respiration

Exchange of gases between the alveoli Exchange of gases between the alveoli and pulmonary capillariesand pulmonary capillaries

Oxygen diffuses from an area of higher Oxygen diffuses from an area of higher concentration to an area of lower oxygen concentration to an area of lower oxygen concentrationconcentration

Oxygen must be available and must be Oxygen must be available and must be able to diffuse across alveolar and able to diffuse across alveolar and capillary membranescapillary membranes

Oxygen must be able to saturate the Oxygen must be able to saturate the hemoglobinhemoglobin

Inadequate External Inadequate External RespirationRespiration

Decreased oxygen available in the Decreased oxygen available in the environmentenvironment Smoke inhalationSmoke inhalation Toxic gas inhalationToxic gas inhalation High altitudesHigh altitudes Enclosures without outside ventilationEnclosures without outside ventilation

Inadequate mechanical ventilationInadequate mechanical ventilation PainPain

Rib fracturesRib fractures PleurisyPleurisy

continuedcontinued Traumatic injuriesTraumatic injuries

Open pneumothoraxOpen pneumothorax Loss of ability to change intrathoracic pressuresLoss of ability to change intrathoracic pressures

Crushing injuries of the neck and chestCrushing injuries of the neck and chest Traumatic asphyxiaTraumatic asphyxia Crushing neck injuriesCrushing neck injuries

Tension pneumothoraxTension pneumothorax Increased intrathoracic pressures reducing Increased intrathoracic pressures reducing

ventilationventilation HemothoraxHemothorax

Blood in thoracic cavity reducing lung expansionBlood in thoracic cavity reducing lung expansion Flail ChestFlail Chest

Loss of ability to change intrathoracic pressuresLoss of ability to change intrathoracic pressures

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Other conditionsOther conditions Upper Airway ObstructionUpper Airway Obstruction

EpiglottitisEpiglottitis CroupCroup Airway Edema-anaphylaxisAirway Edema-anaphylaxis

Lower Airway ObstructionsLower Airway Obstructions AsthmaAsthma Airway Edema from inhalation of toxic Airway Edema from inhalation of toxic

substancessubstances

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HypoventilationHypoventilation Muscle ParalysisMuscle Paralysis

Spinal injuriesSpinal injuries Paralytic drug for intubationParalytic drug for intubation

Drug OverdoseDrug Overdose Respiratory depressantsRespiratory depressants

Brain Stem InjuriesBrain Stem Injuries Damage to the respiratory centerDamage to the respiratory center

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Inadequate oxygen diffusionInadequate oxygen diffusion Pulmonary edemaPulmonary edema

Fluid between alveoli and capillaries inhibit Fluid between alveoli and capillaries inhibit diffusiondiffusion

PneumoniaPneumonia Consolidation reduces surface area of Consolidation reduces surface area of

respiratory membranesrespiratory membranes Reduces the ventilation-perfusion ratioReduces the ventilation-perfusion ratio

COPDCOPD Air trapping in alveoliAir trapping in alveoli Loss of surface area of respiratory membranesLoss of surface area of respiratory membranes

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Pulmonary emboliPulmonary emboli Area of the lung is ventilated but Area of the lung is ventilated but

hypoperfusedhypoperfused Loss of functional respiration membranesLoss of functional respiration membranes

Oxygen TransportOxygen Transport

Most of the oxygen in arterial blood Most of the oxygen in arterial blood is saturated on hemoglobinis saturated on hemoglobin

Red blood cells must be adequate in Red blood cells must be adequate in number and have adequate number and have adequate hemoglobinhemoglobin

Sufficient circulation is necessary to Sufficient circulation is necessary to transport oxygen to the cellular leveltransport oxygen to the cellular level

Inadequate Oxygen Inadequate Oxygen TransportTransport

AnemiaAnemia Reduces red blood cells reduce oxygen carrying Reduces red blood cells reduce oxygen carrying

capacitycapacity Inadequate hemoglobin results in the loss of oxygen Inadequate hemoglobin results in the loss of oxygen

saturationsaturation PoisoningPoisoning

Carbon monoxide on-loads on the hemoglobin more Carbon monoxide on-loads on the hemoglobin more readily preventing oxygen saturation and oxygen readily preventing oxygen saturation and oxygen carrying capacitycarrying capacity

ShockShock Low blood pressures result in inadequate oxygen Low blood pressures result in inadequate oxygen

carrying capacitycarrying capacity

Internal RespirationInternal Respiration

Exchange of gases from the systemic Exchange of gases from the systemic capillaries to the tissue cellscapillaries to the tissue cells

Oxygen must be able to off-load the Oxygen must be able to off-load the hemoglobinhemoglobin

Oxygen moves from a area of higher Oxygen moves from a area of higher concentration to an area of lower concentration to an area of lower concentration of oxygenconcentration of oxygen

Inadequate Internal Inadequate Internal RespirationRespiration

ShockShock Oxygen is not available due to massive Oxygen is not available due to massive

peripheral vasoconstriction or micro-emboliperipheral vasoconstriction or micro-emboli Cellular environment is not conducive to Cellular environment is not conducive to

off-loading oxygenoff-loading oxygen Acid Base ImbalanceAcid Base Imbalance Lower than normal temperatureLower than normal temperature

PoisoningPoisoning CO will reduce the oxygen available at the CO will reduce the oxygen available at the

cellular levelcellular level

Signs and Symptoms of Signs and Symptoms of HypoxemiaHypoxemia

RestlessnessRestlessness Altered or deteriorating mental Altered or deteriorating mental

statusstatus Increased or decreased pulse ratesIncreased or decreased pulse rates Increased or decrease respiratory Increased or decrease respiratory

ratesrates Decreased oxygen oximetry readingsDecreased oxygen oximetry readings Cyanosis (late sign)Cyanosis (late sign)

PathophysiologyPathophysiology

Oxygen is exchanged by diffusion Oxygen is exchanged by diffusion from higher concentrations to lower from higher concentrations to lower concentrationsconcentrations

Most of the oxygen in the arterial Most of the oxygen in the arterial blood is carried bound to hemoglobinblood is carried bound to hemoglobin 97% of total oxygen is normally bound 97% of total oxygen is normally bound

to hemoglobinto hemoglobin 3% of total oxygen is dissolved in the 3% of total oxygen is dissolved in the

plasmaplasma

Oxygen SaturationOxygen Saturation

Percentage of hemoglobin saturated Percentage of hemoglobin saturated with oxygenwith oxygen

Normal SpO2 is 95-98%Normal SpO2 is 95-98% Suspect cellular perfusion Suspect cellular perfusion

compromise if less than 95% SpO2compromise if less than 95% SpO2 Insure adequate airwayInsure adequate airway Provide supplemental oxygenProvide supplemental oxygen Monitor carefully for further changes Monitor carefully for further changes

and intervene appropriatelyand intervene appropriately

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Suspect severe cellular perfusion Suspect severe cellular perfusion compromise when SpO2 is less than compromise when SpO2 is less than 90%90% Insure airway and provide positive Insure airway and provide positive

ventilations if necessaryventilations if necessary Administer high flow oxygen Administer high flow oxygen Head injured patients should never Head injured patients should never

drop below 90% SpO2drop below 90% SpO2

SpO2 and PaO2SpO2 and PaO2

SpO2 indicates the oxygen bound to SpO2 indicates the oxygen bound to hemoglobinhemoglobin Closely corresponds to SaO2 measured Closely corresponds to SaO2 measured

in laboratory testsin laboratory tests SpO2 indicates the saturation was SpO2 indicates the saturation was

obtained with non-invasive oximetryobtained with non-invasive oximetry PaO2 indicates the oxygen dissolved PaO2 indicates the oxygen dissolved

in the plasmain the plasma Measured in ABGsMeasured in ABGs

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Normal PaO2 is 80-100 mmHgNormal PaO2 is 80-100 mmHg NormallyNormally

80-100 mm Hg corresponds to 95-100% 80-100 mm Hg corresponds to 95-100% SpO2SpO2

60 mm Hg corresponds to 90% SpO260 mm Hg corresponds to 90% SpO2 40 mm Hg corresponds to 75% SpO240 mm Hg corresponds to 75% SpO2

TechnologyTechnology The pulse oximeter has Light-emitting The pulse oximeter has Light-emitting

diodes (LEDs) that produce red and diodes (LEDs) that produce red and infrared lightinfrared light

LEDs and the detector are on opposite LEDs and the detector are on opposite sides of the sensorsides of the sensor

Sensor must be place so light passes Sensor must be place so light passes through a capillary bedthrough a capillary bed Requires physiological pulsatile waves to Requires physiological pulsatile waves to

measure saturationmeasure saturation Requires a pulse or a pulse wave (Adequate Requires a pulse or a pulse wave (Adequate

CPR)CPR)

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Oxygenated blood and deoxygenated Oxygenated blood and deoxygenated blood absorb different light sourcesblood absorb different light sources Oxyhemoglobin absorbs more infrared Oxyhemoglobin absorbs more infrared

lightlight Reduced hemoglobin absorbs more red Reduced hemoglobin absorbs more red

lightlight Pulse oximetry reveals arterial Pulse oximetry reveals arterial

saturation my measuring the difference.saturation my measuring the difference.

Patient AssessmentPatient Assessment

Patient assessment should include Patient assessment should include all componentsall components Scene Size-upScene Size-up Initial AssessmentInitial Assessment Rapid Trauma Assessment or Focused Rapid Trauma Assessment or Focused

Physical ExamPhysical Exam Focused HistoryFocused History Vital SignsVital Signs Detailed AssessmentDetailed Assessment Ongoing AssessmentOngoing Assessment

Pulse Oximetry Pulse Oximetry MonitoringMonitoring

Pulse oximetry monitoring is Pulse oximetry monitoring is NOTNOT intended to replace any part of the intended to replace any part of the patient assessmentpatient assessment Pulse oximetry is a useful adjunct in Pulse oximetry is a useful adjunct in

assessing the patient’s oxygenation and assessing the patient’s oxygenation and monitoring treatment interventionsmonitoring treatment interventions

Initiate pulse oximetry immediately Initiate pulse oximetry immediately prior to or concurrently with oxygen prior to or concurrently with oxygen administrationadministration

Continuous MonitoringContinuous Monitoring Monitor current oxygenation status and Monitor current oxygenation status and

response to oxygen therapyresponse to oxygen therapy Monitor response to nebulized treatmentsMonitor response to nebulized treatments Monitor patient following intubationMonitor patient following intubation Monitor patient following positioning Monitor patient following positioning

patients for stabilization and transportpatients for stabilization and transport Decreased circulating oxygen in the Decreased circulating oxygen in the

blood may occur rapidly without blood may occur rapidly without immediate clinical signs and immediate clinical signs and symptomssymptoms

PediatricsPediatrics Use appropriate sized sensorsUse appropriate sized sensors

Adult sensors may be used on arms or feetAdult sensors may be used on arms or feet Active movement may cause erroneous Active movement may cause erroneous

readingsreadings Pulse rate on the oximeter must coincide with Pulse rate on the oximeter must coincide with

palpated pulsepalpated pulse Poor perfusion will cause erroneous Poor perfusion will cause erroneous

readingsreadings Treat patient according to clinical status when Treat patient according to clinical status when

in doubtin doubt Pulse oximetry is useless in pediatric cardiac Pulse oximetry is useless in pediatric cardiac

arrestarrest

Conditions Affecting Conditions Affecting AccuracyAccuracy

Patient conditionsPatient conditions CarboxyhemoglobinCarboxyhemoglobin AnemiaAnemia Hypovolemia/HypotensionHypovolemia/Hypotension HypothermiaHypothermia

CarboxyhemoglobinCarboxyhemoglobin

Carbon monoxide has 200-250 greater Carbon monoxide has 200-250 greater affinity for the hemoglobin molecule than affinity for the hemoglobin molecule than oxygenoxygen Binds at the oxygen binding siteBinds at the oxygen binding site Prevents on-loading of oxygenPrevents on-loading of oxygen Fails of readily off-load at the tissue cellsFails of readily off-load at the tissue cells

Carboxyhemoglobin can not be Carboxyhemoglobin can not be distinguished from oxyhemoglobin by distinguished from oxyhemoglobin by pulse oximetrypulse oximetry Erroneously high reading may presentErroneously high reading may present

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Suspect the presence of Suspect the presence of carboxyhemoglobin in patient with:carboxyhemoglobin in patient with: Smoke inhalationSmoke inhalation Intentional and accidental CO poisoningIntentional and accidental CO poisoning Heavy cigarette smokingHeavy cigarette smoking

Treat carboxyhemoglobin with Treat carboxyhemoglobin with high flow oxygen irregardless of high flow oxygen irregardless of

the pulse oximetry reading!the pulse oximetry reading!

AnemiaAnemia

Low quantities of erythrocytes or Low quantities of erythrocytes or hemoglobinhemoglobin Normal value of hemoglobin is 11-18 g/dlNormal value of hemoglobin is 11-18 g/dl Values as low as 5 g/dl may result in 100% Values as low as 5 g/dl may result in 100%

SpO2SpO2

Anemic patients require high levels Anemic patients require high levels of oxygen to compensate for low of oxygen to compensate for low

oxygen carrying capacities!oxygen carrying capacities!

Hypovolemia/Hypovolemia/HypotensionHypotension

Adequate oxygen saturation but reduced Adequate oxygen saturation but reduced oxygen carrying capacityoxygen carrying capacity

Vasoconstriction or reduction in cardiac Vasoconstriction or reduction in cardiac output may result in loss of detectable output may result in loss of detectable pulsatile waveform at sensor sitepulsatile waveform at sensor site

Patients in shock or receiving Patients in shock or receiving vasoconstrictors may not have adequate vasoconstrictors may not have adequate perfusion to be detected by oximetryperfusion to be detected by oximetry

Always administer oxygen to Always administer oxygen to patients with poor perfusion!patients with poor perfusion!

HypothermiaHypothermia

Severe peripheral vasoconstriction Severe peripheral vasoconstriction may prevent oximetry detectionmay prevent oximetry detection

Shivering may result in erroneous Shivering may result in erroneous oximetry motionoximetry motion Pulse rate on oximeter must coincide Pulse rate on oximeter must coincide

with palpable pulse rate to be with palpable pulse rate to be considered accurateconsidered accurate

Treat the patient according to Treat the patient according to hypothermic guidelines and hypothermic guidelines and

administer oxygen accordingly!administer oxygen accordingly!

Patient EnvironmentsPatient Environments

Ambient LightAmbient Light Excessive MotionExcessive Motion

Ambient LightingAmbient Lighting

Any external light exposure to Any external light exposure to capillary bed where sampling is capillary bed where sampling is occurring may result in an erroneous occurring may result in an erroneous readingreading

Most sensors are designed to Most sensors are designed to prevent light from passing through prevent light from passing through the shell the shell Shielding the sensor by covering the Shielding the sensor by covering the

extremity is acceptableextremity is acceptable

Excessive MotionExcessive Motion

New technology filters out most New technology filters out most motion artifactmotion artifact

Always compare the palpable pulse Always compare the palpable pulse rate with the pulse rate indicated on rate with the pulse rate indicated on the pulse oximetrythe pulse oximetry If they do not coincide, reading must be If they do not coincide, reading must be

considered inaccurateconsidered inaccurate

Other ConcernsOther Concerns

Fingernail polish and pressed on nailsFingernail polish and pressed on nails Most commonly use nails and fingernail Most commonly use nails and fingernail

polish will not affect pulse oximetry polish will not affect pulse oximetry accuracyaccuracy

Some shades of blue, black and green may Some shades of blue, black and green may affect accuracy (remove with acetone pad)affect accuracy (remove with acetone pad)

Metallic flaked polish should be removed Metallic flaked polish should be removed with acetone padwith acetone pad

The sensor may be placed on the ear if The sensor may be placed on the ear if reading is affectedreading is affected

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Skin pigmentationSkin pigmentation Apply sensor to the fingertips of darkly Apply sensor to the fingertips of darkly

pigmented patients.pigmented patients.

Interpreting Pulse Interpreting Pulse OximetryOximetry

Assess and treat the PATIENT Assess and treat the PATIENT not the oximeter!not the oximeter! Use oximetry as an adjunct to patient Use oximetry as an adjunct to patient

assessment and treatment evaluationassessment and treatment evaluation

NEVER withhold oxygen if the NEVER withhold oxygen if the patient ahs signs or symptoms patient ahs signs or symptoms

of hypoxia or hypoxemia of hypoxia or hypoxemia irregardless of oximetry irregardless of oximetry

readings!readings!

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Pulse oximetry measures Pulse oximetry measures oxygenation not ventilationoxygenation not ventilation Pulse oximetry does NOT indicate the Pulse oximetry does NOT indicate the

removal of carbon dioxide from the removal of carbon dioxide from the blood!blood!

DocumentationDocumentation

Pulse oximetry is usually documented as Pulse oximetry is usually documented as SpO2SpO2 Distinguishes non-invasive pulse oximetry Distinguishes non-invasive pulse oximetry

from SaO2 determined by laboratory testingfrom SaO2 determined by laboratory testing Document oximetry readings as Document oximetry readings as

frequently as other vital signsfrequently as other vital signs When oximetry reading is obtained When oximetry reading is obtained

before oxygen administration, designate before oxygen administration, designate the reading as “room air”the reading as “room air”

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When oxygen administration is When oxygen administration is changed, document the evaluation of changed, document the evaluation of pulse oximetrypulse oximetry

When treatments provided could When treatments provided could potentially affect respiration or potentially affect respiration or ventilation, document pulse oximetryventilation, document pulse oximetry Spinal immobilizationSpinal immobilization Shock positionShock position Fluid administrationFluid administration

SummarySummary

As with all monitoring devices, As with all monitoring devices, the interpretation of the interpretation of

information and response to information and response to that interpretation is the that interpretation is the

responsibility of a properly responsibility of a properly trained technician!trained technician!

ReferencesReferences

Bledsoe, B. et al. (2003). Bledsoe, B. et al. (2003). Essentials of paramedic care. Essentials of paramedic care. Upper Saddle Upper Saddle River, New Jersey: Prentice Hall.River, New Jersey: Prentice Hall.

Halstead, D., Progress in pulse oximetry—a powerful tool for EMS Halstead, D., Progress in pulse oximetry—a powerful tool for EMS providers. providers. JEMS, JEMS, 2001: 55-66.2001: 55-66.

Henry, M., Stapleton, E. (1997). Henry, M., Stapleton, E. (1997). EMT prehospital care EMT prehospital care (2(2ndnd ed.). ed.). Philadelphia: W.B. Saunders.Philadelphia: W.B. Saunders.

Limmer, D., et al. (2001) Limmer, D., et al. (2001) Emergency CareEmergency Care (9 (9thth ed.). Upper Saddle River, ed.). Upper Saddle River, New Jersey: Prentice Hall.New Jersey: Prentice Hall.

Porter, R., et al: The fifth vital sign. Porter, R., et al: The fifth vital sign. Emergency, Emergency, 1991 22(3): 127-130.1991 22(3): 127-130.

Sanders, M., (2001). Sanders, M., (2001). Paramedic textbook Paramedic textbook (rev. 2(rev. 2ndnd ed.). St. Louis: Mosby. ed.). St. Louis: Mosby.

Shade, B., et al. (2002). Shade, B., et al. (2002). EMT intermediate textbookEMT intermediate textbook (2 (2ndnd ed.). St. Louis: ed.). St. Louis: Mosby.Mosby.

Cason, D., Pons, P. (1997) Cason, D., Pons, P. (1997) Paramedic field care: a complaint approach. Paramedic field care: a complaint approach. St. St. Louis: Mosby. Louis: Mosby.