Table of Contents
Introduction and History 1
The Principles Of Laser Doppler Flowmetry 2
Clinical Applications 4
Recent Developments 4
Glossary 5
Works Cited 6
Introduction and History
Laser Doppler flowmetry, or LDF, is a unique way to measure the microcirculatory blood flow without a painful or invasive procedure. LDF uses the Doppler shift theory as a way to transmit the information, with the scattering of light coming from the laser by way of the red blood cells. [A, B, C] Micro-vascular applications have greatly benefited from this type of technology. The accuracy and reproducibility can be shown after years of extensive research. It can continuously monitor the blood flow and between every two to five seconds give an average output value. [E]
The blood cell velocity in capillaries is too low to use the technique of the Doppler shift using ultrasound, as the frequencies of the sound that would reverberate back would be too small to identify. [B] Using the laser, calculations based upon the measurements between the primary light source’s frequencies that were transferred towards the vasculature and the reflective light coming back towards the source can determine the blood flow’s velocity. [B] This non-destructive way to assess microcirculatory function has been around for approximately 40 years now in its realised state. The proposed device became experimentally plausible in 1972 when Riva used LDF for measuring retina vessels in rabbits. [D] Around 1980 another
In Exercise 1, diaminofluorene is used to determine the hemoglobin concentration in the daphnids. A higher hemoglobin concentration is indicated by a darker blue color. A spectrophotometer was used to determine the absorbance at 610nm. When measuring the absorbance levels a blank is necessary to have a zero reference, the blank is the “starting point” for the measurements of the sample (re-word). The blank consists of 10µL of diaminofluorene(DAF), 50µL of hydrogen peroxide, and 0.5mL of PBS. The PBS acts as a buffer in this experiment. The cuvette with the sample of daphnids consisted of 10µL of DAF, 50µL of hydrogen peroxide, and 0.5mL of the sample of Daphnia. In Exercise 2, the Pasteur pipette was used to obtain the sample of Daphnia. The depression slide used in this experiment isolated the daphnid, cotton was used to keep the daphnid still while the heartbeat was counted. The ocular micrometer on the microscope allows the tail spine length to be measured accurately, as well as using an ocular magnification table.
All tests were conducted in the same posture; leaning over the lab table with elbows resting on the table and the head down. Students worked in groups of three to four, and each one took turn being the experimental subject, taking the pulse and handling the stopwatch. To measure the radial pulse manually, the subject’s palm was facing upward. The index and middle fingers were used to locate the pulse between the radial bone, which is on the same side as the thumb, and with a slight pressure, the pulse could be found.
The purpose of arterial pressure and the pulse lab is to determine the effect of posture and exercise on systolic and diastolic pressure and the heart rate. And also in order to find the differences in the reading taken under these condition compares to the baseline reading. The Sphygmomanometer and stethoscope are used to measure the systolic and diastolic blood pressure, counting the beat on the radial artery will give the reading for pulse rate and by using the lab scribe software and IWX214, the blood pressure will be measured. In the heart, the aorta and the carotid arteries have baroreceptors and the chemoreceptors that identify the changes in arterial pressure and the changes in
The materials used to preform the lab include; living Daphnia, water, 3 pieces of thread, slide and cover slides, microscope, alcohol substance. The pieces of thread will be used to keep the Daphnia in place on the slide under the microscope. Placing the Daphnia under the microscope we were able to see the heart located on the upper part of the Daphnia. With the transparent structure of the Daphnia. We are able to visually see the solution affecting the heart beats. Before applying the solution we took the three readings of the normal Daphnia heart rate for 15 seconds and multiply the number by 4 to collect the number of 1 minute. After we applied the same method observing the heart beat affected by the solution and recorded the heart beats
"Oscillatory Blood Pressure Monitoring Devices." BMJ : British Medical Journal. BMJ, 20 Oct. 2001. Web. 16 Dec. 2016. .
As you have seen, a pulse is measured as the distention of an artery that can be felt each time the heart contracts. Pulse is measured in number of beats per minute. You can measure pulse anywhere an artery passes close to the skin. Clinically, it is most common to measure heart rate in the radial artery on the inside of the wrist. The figure shows you the procedure.
Fig (34): Spurious spectral broadening visualized in (A) due to large sample volume. When sample-volume size is reduced, the accurate depiction of flow velocities within the vessel is seen in image (B) (Barr RG, 2012).
Assessing an arterial line the nurse looks at the insertion site does it look red, swollen, is the transducer even with the patient’s right atrium and does the BP readings look accurate? To monitor for accurate circulation, you look at circulation below the site, is there a pulse and are the extremities looking blue? A benefit of this is having a constant BP reading and tells the patients temperature. Some negatives is that it can be an extra risk for infection. Potential complications is the lower part of the extremity is not receiving adequate
• Molecules with small differences in absorption wavelengths can be detected well due to their differences in separation time. i.e one which travels faster is measured prior to the other which is measured later. This is the prime advantages if HPLC which makes it
The pulse is an indication of an individual’s heart rate. When checking for a pulse in the primary survey, begin with palpating the patient’s radial or carotid artery (Basic Patient Care 2012, p. 50). This may reveal a normal (60-100 beats/min), tachycardia (<100 beats/min), bradycardia (> 60 beats/min) or asystole heart rate. Additionally, the capillary refill may also provide details about a patient’s cardiovascular status. This is performed by applying pressure to the nail bed and calculating the time it to takes to refill to a normal color, which should take no more then a few seconds otherwise suggesting capillary closure (Mick J Sanders, 2012, p. 1400). An additional accessory to Circulation is Hemorrhages, these involve more through examinations of the pulse, blood pressure and warmth of peripheries of patients. Additionally, you must thoroughly look for indication of bleeding, specifically in the areas around the chest, abdomen and externally seen by the eye.
Blood is a highly specialized complex connective tissue with a unique fluid of variable composition circulating through the heart, arteries, capillaries, and veins, known as the vascular system of the body (???). Blood approximately accounts of 8% of the body weight, with female body consists of 4-5 litres while males have around 5-6 litters. This variation is mainly due to the difference in body size between men and women (@@@). Human blood has a pH of 7.35-7.45, this makes the blood to be basic in nature. The viscous nature of blood makes it more resistant to flow than water. Unless blood is viscous, it can strain the heart and lead to severe cardiovascular problems (@@@). Due to the presence of high oxygen in arteries,
Lasers treatments work by producing heat when interaction with the skin takes place. A quite high beam of light is passed through the skin at the dermal level which makes it quite hot and stimulates the cells which produce elastin& collagen. The laser is also targeted to coloured lesions such as broken blood
appear similar to conventional stents.”8 Middleton, Teefey and Darcy8 note that the use of PFTE endografts will likely become standard as their performance outweighs the early stent materials used. Color Doppler as well as pulsed Doppler should be used to interrogate the stent and supporting vessels. Velocity measurements are taken using angle correct and spectral waveforms are recorded. Careful examination of the liver vasculature is imperative to verify proper stent function. Specifically, thrombosis or occlusion can be assessed with color and Doppler ultrasound. Velocity parameters may vary from patient to patient and also will change from immediate post procedure velocities to those obtained during long term follow up. Universal Doppler
As the blood flows in the blood vessels, the blood, just like any other fluids, experiences a viscous drag. Viscosity is experienced when a layer of liquid within a given flowing liquid exerts frictional forces on the other layers of flowing liquid due to different velocities with these separate layers of liquid are flowing at. The fluids that are flowing at a relatively slower velocity mostly found on the external layer of the fluid flowing will exert on the layers of fluid flowing in the internal parts of the fluid a viscous drag. The difference in the velocities of flow of the two layers of the same liquid could be caused by frictional forces between the external layer of the flowing liquid and the walls of the blood vessels as they move about the circulatory system.
A negative relationship between the RBC concentration and LIM voltage is observed, when more blood is added to the isotonic saline solution, blood concentration increased, therefore the protein concentration become greater in the solution. The greater concentration of protein in the solution the more light is scattered. The intensity of the scattered light increased, resulted in a lower voltage was detected by the LIM device. Thus resulted in a trend of decreasing voltage with an increasing blood concentration. Figure 1 indicates that the output of the LIM is linear. RBCs were added in an isotonic solution, which means there will be no net water movement between the saline solution and the RBCs. When the blood concentration increased the voltage is decreased, therefore, an inversely proportional relationship is observed between the two variables (y = -0.1069x + 0.0885). Hence, the concentration of blood in the unknown solution is 12.05 µLml-1.