Advanced Techniques used to Assess Body Composition Demonstration
Monday 30th January 2017
9am-12noon, 1pm-4pm; EM0026
Group allocations for this practical will be made available on StudySpace on Friday 25th November 2016. If you cannot make your session and wish to swap, please contact me by Monday 12th December 2016.
Demonstration:
In your practical groups you will be required to demonstrate two methods, sometimes referred to as types of advanced body composition techniques, air displacement plethysmography (ADP OR BodPoD) and bioimpedance analysis (BIA) to me (Dr Elizabeth Opara). To prepare fully for this demonstration you are advised to do the reading and advanced techniques tutorial provided on StudySpace (in the ‘Advanced Techniques folder, which will be made available on 16/01/17. This demonstration is also linked to the lecture on cancer cachexia so you are advised to attend.
You will also be required as part of the demonstration to answer the following questions:
- What is the 2C model?
- Why do you think it is used to estimate body composition?
- On what assumptions is this model based?
- Do you think that because of these assumptions the 2C model has limitations? Why?
- What is the science on which the use of air displacement plethysmography (ADP) to estimate body composition based?
- What is the science on which the use of bioimpedance analysis (BIA) to estimate body composition based?
- What factors affect the accuracy of these techniques?
- What other advanced techniques are there?
- What are the advantages and disadvantages of these techniques?
- What other models can be used to estimate body composition?
Although you are required to attend the demonstration (see general guidelines for information regarding the consequences of non-attendance) your ability to carry out the demonstration and to answer the questions WILL NOT be assessed summatively (i.e. you will receive no marks for the demonstration and for answering the questions). However, it is in your best interests to engage fully in this demonstration as this will increase your chance of obtaining a good mark for the write up (consider this demonstration as part of the feed-forward you will receive for this practical). Dr Opara WILL NOT answer any of the questions for you however she will provide you with guidance if necessary to help you answer the questions. Furthermore, she will provide you with feedback and direct you to appropriate reading material if she feels that it is necessary. Please feel free to ask questions concerning the techniques that will be demonstrated and discussed.
Assignment Guidelines:
- Is the 2C model using the Siri equation the best way to assess body composition in those with cancer cachexia? (1 mark). Using data from the literature give reasons for your answer (8 marks). 150 words
- You have been asked to choose ONE advanced body composition technique, from the list below, to assess the body composition, specifically fat mass and fat free mass, of patients with cancer cachexia. Your answer must include a clear, but brief, description of your method of choice, which must include the scientific basis for the method; you are expected to compare and contrast your method of choice with ALL the other methods. (20 marks)
List of advanced techniques:
Air displacement plethysmography (BODPOD),
Bioimpedance analysis (BIA),
Computed tomography (CT).
Dual energy X-ray absorptiometry (DEXA),
Magnetic resonance imaging (MRI)
Under water weighing (UWW),
- What mechanisms appear to underpin the changes in body composition that occur in those with cancer cachexia? (10 marks).
For Q1)
| Parameter | Normal, kg | Cachectic, kg |
| Total body weight | 65.6 | 44.9 |
| Total fat | 17.3 | 3.1 |
| Muscle protein | 2.8 | 0.7 |
| Nonmuscle protein | 8.3 | 8.1 |
| Intracellular water | 19.1 | 12.9 |
| Extracellular water | 15.1 | 17.5 |
| Minerals | 3.0 | 2.6 |
TABLE 1.
Comparison of body composition of cachectic cancer patients with normal controls
Data from Fearon (1992) Proc Nut Soc 51: 251-265
Q2:
The answer will be DEXA
Talk about DEXA especially for this cancer and brief description for other according to this cancer. Limitation for each one , evidence using literature
