This diagram depicts some of the physical and physiologic factors that affect the thermoreceptor (TR) discharge rate and consequently the temperature sensed in an examiner’s skin in contact with a patient’s skin. The temperature and its rate of change of the examiner’s thermoreceptors are functions of the net effects of the time that the tissues are in contact, their contact area (A), the temperatures (TBe and TBp) and volume flow rates (Ve and Vp) of blood perfusing the examiner’s and patient’s skin, epidermal thickness (Xe and Xp) and thermal conductivity (Ke and Kp) of both, dermal temperature (TDe and TDp) of both, as well of the net heat exchange rate (QH) between the two tissues. QH is strongly affected by the heat transfer properties of material trapped between the two skin surfaces, for example air, water, oil, grease, hand lotion, dirt, tissue debris, fabric (Adams et al 1982).
Note: This posting is a copy of an article appearing in the June 2008 issue of MassageToday
Palpation lies at the heart of much that we do in manual medicine and bodywork in general, and massage in particular, but how accurate and reliable is it?
What we do therapeutically is commonly determined by prior palpation, and the meaning we give to what has been palpated. In other words we assess and decide what treatment is needed, and then apply techniques in order to achieve those ends. If however our palpation skills are limited, or our interpretation of what it is we are feeling, is inaccurate, then the treatment we choose to apply – based on such misinformation- is likely to fail.
Famous osteopathic physician Viola Fryman (1963) has said:
“Palpation cannot be learned by reading or listening; it can only be learned by palpation.”
Palpation represents a two way communication between the examiner and the patient, and often, decisions as to what to do therapeutically will be based on a variety of palpation and assessment methods, together with the symptoms complained of, and the patient’s responses to these manual (and sometimes observational) evaluation procedures.
In other instances – I am thinking of methods such as neuromuscular technique, or many massage techniques – palpation and treatment are synchronous with decisions over how we should respond by varying the degree, duration and directions of forces.
These decisions are determined by what is being assessed/’felt’ by the contact hand(s), and how this is interpreted, in real time, moment by moment. So what is being done therapeutically, in such a setting, is directly related to what is being palpated and assessed – at that moment – rather than having been planned ahead.
• How firmly or softly or variably, is pressure being applied?
• How rapidly, slowly?
• For how long?
• In what direction(s)?
• And in which combinations of compression, distraction, torsion, shearing, vibration etc – locally or generally?
• And how do the tissue responses – local and/or reflexive – to such treatment variables, modify the procedures being used, as they soften, tense, release, change, mobilise etc?
• Equally importantly how does verbal feedback from the patient/client modify these processes?
For experienced practitioners and therapists much of the instant decision-making, that results in modifications of application of forces (compression/stretch etc) happens without due deliberation – the hands do the thinking – intuitively, so to speak. – in much the same way that a tightrope walker makes instant – non-cognitive – decisions based on the processing of multiple pieces of information.
In other circumstances, active deliberation and thought is required as to what to do next.
How accurate such decision making is, will be based on a combination of experience, learned information, as well as being ‘present in the moment‘, and truly in touch with tissues that offer information that requires interpretation?
So, at the heart of palpation is what many years ago I termed ‘palpatory literacy’. Do we know how to read the signs and signals the body and its’ tissues offer us?
Nowadays, with the clamour for ‘evidence based’ methods, a great deal of effort goes into evaluating how reliable and how valid (accurate) palpation and assessment methods are.
These can be looked at in several ways. The most common being studies that try to see how reliable an examiner’s findings (and therefore the methods used) are. This is measurement of intra-examiner reliability
The other major focus is on how repeatable findings are, when different examiners are involved. This is measuring inter-examiner reliability.
The difference between these, is that one (intra) looks at how competent you are in making judgements about what you palpate, and whether the same findings are repeatable when you apply them to other people, or other tissues, that display similar characteristics (edematous, hypertonic etc).
Do your findings commonly agree with previous findings that you have come to?
In which case there is good intra-examiner reliability.
Inter-examiner evaluation, looks at how much agreement there is when others palpate the same tissues. Do they come to the same conclusions that you did?
In which case there is good inter-examiner reliability.
It’s worth reminding ourselves that such reliability does not necessarily mean that accuracy has been achieved. The interpretation of methods of palpation that can reliably be duplicated, and which agree with the palpation findings of someone else, does not in and of itself mean that the conclusions deriving from the palpation exercise are accurate. You may both be wrong – depending on what you are basing your interpretation of similar palpation findings on.
For example you could reliably aim at, and hit a dartboard every time you threw a dart…… and this would reflect your throwing reliability. But only if you consistently, or frequently, hit the bulls-eye, would the dart throwing be categorised as accurate!
So how can we ensure better intra- and inter-examiner reliability – and accuracy?
There are a number of ways, and I’ve explored these in my book Palpation and Assessment Skills (Churchill Livingstone/Elsevier. ISBN – 0443072183) which attempts to lead the reader through multiple graduated exercises, that should result in enhanced skills.
Assessment and palpation methods need to be standardized, well taught, and regularly assessed for both reliability and validity (accuracy)?
The acronym STAR is used in osteopathic medicine to describe characteristic s that are commonly present – and assessable – when dysfunction exists.
S = sensitivity, because dysfunction usually increases sensitivity, soreness, pain
T = Tissue texture, because dysfunctional tissues usually ‘feel’ different to surrounding or ‘normal’ tissues (spasm, hyper or hypotonic, ‘boggy’, fibrous etc).
A – Asymmetry, because commonly the same tissues on the other side of the body are different, more ‘normal’.
R = range of motion, because tissues that are dysfunctional will commonly display a decreased (sometimes increased) range – whether this be a joint, or soft tissues, or the skin overlying these.
Some of these elements are measurable, and some not. In other words some are subjective (tissue texture for example) and some are objective (range of motion for example).
One thing is certain – the more you practice palpation methods the more sensitive and reliable your methods should become.
What your palpation and assessment findings mean depends on the degree of knowledge you have acquired, and your particular belief system. For example when palpating the radial pulse your belief system may cause you to interpret findings as relating to heart rate, whereas someone else, who appears to be performing precisely the same palpation, might be evaluating chi levels in different meridian systems.
I will return to the vast topic of palpation in a future posting
REFERENCES
Adams T, Steinmetz J, Heisey R et al 1982 Physiologic basis for skin properties in palpatory physical diagnosis. Journal of the American Osteopathic Association
Frymann V 1963 Palpation – its study in the workshop. Academy of Applied Osteopathy Yearbook, Newark, OH, pp 16–30