Pulse Oximetry

Overview:

Oxygen saturation is a relative measure of the quantity of dissolved or carried oxygen in a given medium. In medicine, oxygen saturation (SO₂) is measured as percentage of hemoglobin binding sites occupied by oxygen in the bloodstream. At low partial pressures of oxygen, most hemoglobin is deoxygenated.

The oxygen saturation level may be measured from different areas of the body and include:

• Arterial oxygen saturation (SaO₂) to measure of the amount of oxygen bound to hemoglobin in the arterial system; commonly referred to Saturation of Peripheral Oxygen (SpO₂) a when measured using oximetry
• Venous oxygen saturation (SvO₂) to measure how much oxygen the body consumes
• Tissue oxygen saturation (StO₂) can be measured by near infrared spectroscopy to estimate tissue oxygenation in various conditions.

Method:

Arterial oxygen saturation can be measured using non-invasive oximetry techniques and avoids technical and ethical concerns associated with arterial sampling for blood oxygen (O₂) level determination.

Pulse oximetry or oximetry is a non-invasive method, which relies on the light absorption characteristics of saturated hemoglobin and thus allows monitoring of the oxygenation of a subject's haemoglobin. This involves placing a sensor on a thin part of the subject’s anatomy such as a fingertip or earlobe. A light containing both red and infrared wavelengths is passed from one side to the other. These light waveforms are transmitted by a semiconductor light emitting diode and detected by a photodetector.

Oximetry determines SaO₂ by analyzing two wavelengths of light (660 nm and 910 nm) that are differentially absorbed by specific hemoglobin structures in the blood. Oxygenated hemoglobin (HbO₂) absorbs more infrared light and allows more red light to pass through. Deoxygenated hemoglobin (Hb) absorbs more red light and allows more infrared light to pass through. The relative absorption of these wavelengths reflects the ratio of oxygenated to total hemoglobin and this ratio is expressed as a percentage. As oximetry does not detect the presence of carboxyhemoglobin and methemoglobin, SaO₂ must strictly be referred to as SpO₂. For a healthy human adult, a SpO₂ of 97% to 99% is considered normal.

 

Software:

LabChart
LabChart software (for Windows and Macintosh) combines the familiar simplicity of a traditional strip chart recorder with the powerful analysis features of a digital acquisition system. LabChart software and a PowerLab data acquisition unit provide data integrity, easy selection of hardware settings, powerful online and offline analysis, procedure automation, seamless extraction of experimental data and flexible display options. Acquisition and analysis capabilities can be further increased with LabChart Extensions and LabChart Modules. LabChart Modules are available as part of LabChart Pro and LabChart Extensions are free for download from the website for existing LabChart users.

 

GLP and 21 CFR Part 11
For those researchers working within a laboratory requiring GLP and 21 CFR Part 11 compliance the GLP Client and GLP Server are available for use with LabChart (Windows only) and PowerLab data acquisition systems. For more information, visit the Good Laboratory Practice application page or contact your nearest ADInstruments representative.
 

Hardware:

PowerLab Data Acquisition Systems
The PowerLab is a high-performance data acquisition unit suitable for a wide range of research applications. Typical applications include human and animal physiology, pharmacology, neurophysiology, biology, zoology, biochemistry, and biomedical engineering. Units are capable of recording at speeds of up to 400 000 samples per second continuously to disk (aggregate), and are compatible with instruments, signal conditioners and transducers supplied by ADInstruments, as well as many other brands. In addition to standard single-ended BNC inputs, 4 differential Pod ports are also available for direct connection of Pod signal conditioners and appropriate transducers. These systems include:

• ML866 PowerLab 4/30 - 4 Channels
• ML870 PowerLab 8/30 – 8 Channels
• ML880 PowerLab 16/30 – 16 Channels

PowerLab can also record pulse oximetry signals from meters that have an analog voltage recorder output such as those provided by:

• Nonin Medical Inc.
• Nellcor
• Datex-Ohmeda

Signal Conditoner
The Oximeter Pod connects to PowerLab models with Pod Ports or to the ML305 Pod Expander for use with PowerLabs without Pod Ports.

The Oximeter Pod takes approximately 10 seconds to determine an accurate output from the time it is plugged in and the transducer is attached to the subject. It only provides a reading of SpO₂, with no associated pulse rate signal. The Oximeter Pod will provide an output signal between 70 to 100% SpO₂ (values below 70% will not be registered). It provides one reading per second with a resolution of 1%.

Blood oxygen saturation (SpO₂) in human subjects can be monitored with the:

• ML320/F Oximeter Pod (Finger clip) that is supplied with a Finger SpO₂ Sensor
• ML320/E Oximeter Pod (Ear clip) that is supplied with an Ear Clip SpO₂ Sensor

Blood oxygen saturation (SpO₂) in animals can be monitored with the:

• ML325/AC Animal Oximeter Pod (Animal Clip) that is supplied with an Animal Clip SpO₂ Sensor
• ML325/AW Animal Oximeter Pod (Tail Wrap) that is supplied with a Tail Wrap SpO₂ Sensor
• ML325/BS Animal Oximeter Pod (Base Sensor) that is supplied with a Base Sensor Transducer

Oximeter Pod Sensors

• MLT321 SpO2 Finger Clip
• MLT322 SpO2 Ear Clip
• MLT323 SpO2 Animal Clip
• MLT324 SpO2 Tail Wrap
• MLT325 Base Sensor Transducer

Instrument

A specialized oximeter for small animals is also available for providing multiple cardiopulmonary measurements from one non-invasive sensor clip. These cardiopulmonary signals can be recorded using the MouseOx software and with a PowerLab data acquisition system with the use of the MLE1071 STARR-Link analog output module. The Small Animal Pulse Oximeter is available in several configurations that include:

• MLE1115-V Small Animal Pulse Oximeter
• MLE1116-V Small Animal Oximeter with Pulse Output
• MLE1117-V Small Animal Pulse Oximeter with MRI Sensor
• MLE1118-V Small Animal Pulse Oximeter with Pulse Output and MRI Sensor

 MLE1115-V and MLE1116-V Oximeters are supplied with: 

• Small Animal Pulse Oximeter
• MLE1103 ManualSpin^TM Hand Commutator
• MLE1101 Universal Connector Cable (6 ft)
• Sample sensor pack
  • 1x Mouse Thigh Sensor
  • 1x S CollarClip
  • 1x S ThroatClip
  • 1x Rat Foot Sensor
  • 1x L CollarClip
  • 1x L ThroatClip
  • 6x Blank Clips
• Standard USB 2.0 Cable (6 ft)
• MouseOx Software

Bags of 5 sensors are also available for purchase separately:

• MLE1120 XS CollarClips (5 pk)
• MLE1121 S CollarClips (5 pk)
• MLE1122 M CollarClips (5 pk)
• MLE1123 L CollarClips (5 pk)
• MLE1124 XL CollarClips (5 pk)
• MLE1125 XXL CollarClips (5 pk)


• MLE1132 XS ThroatClips (5 pk)
• MLE1133 S ThroatClips (5 pk)
• MLE1134 M ThroatClips (5 pk)
• MLE1136 L ThroatClips (5 pk)
• MLE1137 XL ThroatClips (5 pk)
• MLE1138 XXL ThroatClips (5 pk)


• MLE1126 Mouse Thigh Sensor (5 pk)
• MLE1139 Rat Foot Sensor (5 pk)

 MLE1117-V and MLE1118-V Oximeters are supplied with: 

• Small Animal Pulse Oximeter
• MLE1111 MRI Sensor (20 ft)
  • 2x MRI Mouse Thigh Clips
  • 2x MRI Rat Foot Clips
• Standard USB 2.0 Cable (6 ft)
• MouseOx Software

Human G protein Beta-3 subunit variant does not alter hypercarbic or hypoxic ventilatory response
H J Exner; H Groeben; D Rosskopf; W Siffert and J Peters, Clinical Physiology, 612-620, 2001

Sleep-Disordered Breathing and School Performance in Children.
David Gozal, Pediatrics, 616-620, 1998