Issue 6
Issue 6 - October 2011
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Issue 6 - October 2011 |
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From the Editors Desk
It is my greatest pleasure to welcome you to another edition of The Responder, Be Safe Paramedical’s official newsletter. It was rather an emotional experience watching the demise of the Bokke in the RWC quarter finals with a rather rowdy bunch of Americans here in the Gulf of Mexico. It was certainly not a very profitable world cup for me, as I think I was far too optimistic of the Bokke taking the title. So much so that I am now out of a few $10 notes?. I don’t think the locals here understood the concept of “our blood is green” as many thought I was referring to some sort of tropical disease... let’s just say that I had very few patients visiting me after making that quote public out here... I was really excited to hear that the Metro Emergency Medical Services in the Western Cape have taken delivery of two specialised paediatric ambulances. What an exciting concept. I am really looking forward to seeing the results of this initiative. Well done Dr. Robertson and crew... Be Safe is very pleased to announce that we have acquired a stand at the upcoming Emergency Medicine in the Developing World Conference to be held at the Cape Town International Convention Centre from the 15 – 17 November 2011. See the Be Safe Paramedical News Column for details. Pulse Oximeter has become an extremely valuable part of patient monitoring across healthcare disciplines. This month’s article focuses on the basics of pulse Oximeter. Be Safe is pleased to offer you some fantastic specials on a range of quality products. Don’t delay; take advantage of these specials today. We are pleased to introduce our readers to our latest pulse Oximeter/ Capnograph in our product showcase column. This really is an excellent little unit and will be of huge benefit to patient care. Just check out the specs. With that said, I wish you happy reading...
Yours in Healthcare
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Be Safe Specials
Pulse Oximeter - H10 Finger Oximeter
Jet Pull Tourniquet
Pupil Torch - Semi Disposable
Pupil Torch - Steel with Pupil Gauge
Rescue Scissors
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Health Focus Pulse Oximeter - The Basics |
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Is it not amazing how pulse oximeters have evolved over the past several years? I can recall the early days of my career where our pulse oximeters were bigger than most portable transport ventilators are nowadays. With ongoing technology, we have become spoilt for choice from a wide range of units that seem to be getting smaller and smaller. It is an extremely competitive market with companies investing millions of Rands into research and development, in an attempt to produce models that provide superiorly accurate results. There is no doubt that pulse Oximeter plays a crucial part in patient monitoring, however it must be said that one should not use it without considering important factors such as, patient medical history, clinical examination findings and if there are any other factors that could influence the readings presented by the pulse Oximeter. In this article, I would like to focus on the basics of pulse Oximeter and some of the pros and cons associated with its use. History of Pulse Oximeter In 1935 Karl Matthes from Leipzig, Germany, built the first device to continuously measure blood oxygen saturation by transilluminating tissue on the ear. He used two wavelengths of light, one of which was sensitive to changes in oxygen saturation and the other, which was in the infra-red range, to compensate for the variances of tissue thickness, haemoglobin content and light intensity. This device was groundbreaking in being able to monitor saturation trends; however, it was extremely difficult to calibrate, not very portable and was not able to produce absolute values. In comparison to today’s unit, it was also frightfully expensive. The “modern day” pulse oximeter was developed in 1974 by Takuo Aoyagi and Michio Kishi, who were bioengineers at Nihon Kohden. It was first tested on a patient by a surgeon named Susumu Nakajima. His findings were published in 1975. The first commercially available pulse oximeter was launched by Biox in 1981. Over the years the technology has evolved into the current ‘cost-effective’ units which can be found being widely used across the healthcare fraternity. Pulse Oximeter has proved to be one of the most important advances in respiratory monitoring. Definition Pulse Oximeter (SpO2) is a non-invasive (non skin penetrating) monitoring technique that enables Healthcare Professionals to rapidly measure oxygen saturation of haemoglobin in arterial blood. This is achieved by making use of a device called a pulse oximeter which provides a reading as a percentage, i.e. percentage of available haemoglobin saturated with oxygen (or other gas). How a Pulse Oximeter Works Oxygenated blood absorbs light at 660nm (red light), whereas deoxygenated blood absorbs light preferentially at 940nm (infra-red). One nanometer (nm) is equal to 1 billionth of a meter.
Much of the light is absorbed by structures within the finger, i.e. tissue, bone and venous blood; however a portion of it reaches the light detector. Oxygenated haemoglobin (oxyhaemoglobin or O2Hb) absorbs more infrared light than red light. Deoxygenated haemoglobin (Hb) absorbs more red light than infrared light. By comparing the amounts of red and infrared light received at the light detector, the pulse oximeter calculates the oxygen saturation and displays it on a screen as a percentage.
One of the major benefits of pulse Oximeter is that it provides continuous non-invasive monitoring of oxygen saturation. Prior to the availability of pulse Oximeter, arterial blood gas (ABG) analysis was been used to determine haemoglobin saturation. This involves taking an arterial blood sample (usually from the radial artery) running it through an ABG machine and waiting for results. The results of numerous surveys conducted have indicated a downward trend in oxygen saturation related lab tests since the wide scale introduction of pulse oximeters. This has two spin-offs. Firstly it reduces the costs associated with unnecessary lab testing on patients that are otherwise deemed to be ‘relatively’ stable. Secondly, because it is non-invasive, it reduces patient exposure to pain and complications associated with taking samples for testing. I have firsthand experience of the joys of having arterial samples taken and it wasn’t a pleasant experience by any means. Furthermore, relying on physical hypoxic signs in a patient, such as cyanosis, is dangerous, as it is usually picked up at a very late stage. Pulse Oximeter desaturation will occur significantly sooner thereby prompting healthcare providers to reassess the patient clinically and take the necessary action. Low saturation alarms found on all machines provide valuable warning. It is however important to note that pulse Oximeter does not provide the additional information that is obtained from arterial blood gas analysis. pH, partial pressure of oxygen (PO2), carbon dioxide (PCO2), standard bicarb, base excess and oxygen saturation are all obtained from ABG’s and provide crucial information when treating patients with acid-base disturbances related to a compromised respiratory system. Limitations of Pulse Oximeter There are several limitations to pulse Oximeter that may produce inaccurate or false readings. We’ll discuss a few. Carbon Monoxide poisoning Pulse Oximeter only reads the percentage of bound haemoglobin; it cannot determine what gas has actually bonded to the haemoglobin. As such, a patient with carbon monoxide poisoning may exhibit normal pulse Oximeter readings despite inadequate oxygen transport. This may significantly delay the recognition of hypoxaemia in these patients. The events leading up to the emergency that is being treated becomes crucial information in interpreting the pulse Oximeter results. Anaemia Peripherally vasoconstricted patients Nail polish and dirt under the finger nails One of the ways that poor readings through nail polish can be overcome is to move the probe so that it transmits light from one side of the finger to the other, rather than through the nail bed. Alternatively, use another site such as an ear or toe. Bright external light source Failure to detect hypoventilation A combination pulse oximeter/ Capnograph provide a far better range of monitoring. A capnograph measures CO2 in exhaled air and is thus the monitor of choice to pick up acute events such as a dislodged endotracheal tube. A pulse oximeter will only pick up the consequences of an acute event (hypoxia) and may result in significant time delay before healthcare providers may respond and correct the problem. In Conclusion Pulse Oximeter provides extremely valuable information when monitoring acutely ill patients. The cost effectiveness of modern day pulse oximeters has seen them being widely utilised in both in-hospital and pre-hospital medicine. The limitations associated with pulse Oximeter should always be considered when evaluating results. Failure to do so may paint a confusing picture of the patient. With the large amounts of money being invested in pulse Oximeter research and technology we will no doubt see a continued improvement in the quality and accuracy of data being produced by future designs of the pulse oximeter. Be Safe Paramedical markets and sells a range of excellent quality pulse oximeters. These include the small finger type to the technologically superior oxygen saturation/ capnograph combination monitor. Give us a call or drop us an email at
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for further information regarding our range of products.
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Be Safe Product Showcase NT1D Handheld Pulse Oximeter / Capnograph Be Safe Paramedical is pleased to introduce you to the NT1D combination SPO2/ CO2 vital signs monitor from Solaris.
This vital signs monitor boasts the following features: • Bright 2.4 inch TFT LCD Colour Display
Contact us for more information or to place your orders. This e-mail address is being protected from spambots. You need JavaScript enabled to view it |
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Healthcare Fun The Evolution of Medicine I have an earache... 2000BC – Here eat this root 1000AD – That root is heathen. Here say this prayer 1850AD – That prayer is superstition. Here drink this potion 1940AD – That potion is snake oil. Here take this pill. 1985AD – That pill is ineffective. Here take this antibiotic 2000AD – That antibiotic is artificial. Here eat this root. |
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Be Safe Paramedical News Be Safe is pleased to announce that we have acquired a stand at the Emergency Medicine in the Developing World Conference scheduled at the Cape Town International Convention Centre from the 15 – 17 November 2011. Our stand (no 27) is located in the Strelitzia Restaurant within the centre. We are very excited about being able to showcase some of our quality products. Please feel free to pop in for a chat, as we would love to meet as many of you as we can. This is going to be a bumper of a Conference with a host of well known South African and international speakers and should not be missed. Registration is still open and all details and forms can be found at http://www.2011.emssa.org.za/registration We look forward to seeing you there!
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A pulse oximeter probe consists of a light source (red – 660nm and infrared – 940nm) at one end and a light detector at the other end. When the probe is placed on a finger the red and infrared light from the source passes through the finger towards the light detector. 
