Objectives:


Students should be able to:

1. Describe the need for consent in the Doctor-patient relationship.
2.Describe the concept of competence to give consent/refusal for overall treatment.
3. Describe what is meant by blood pressure, know expected values and have an overall view of how it is normally maintained.
4. Describe the nature, mechanism, possible causes and management of a “faint”.
5. Describe why stitches would promote wound healing and prevent scarring.



1. Describe the need for Consent in the Doctor-Patient Relationship:

Full details of the GMC's Guidelines on consent can be found on their website (see sources)

A successful relationship between a doctor and patient is heavily dependent on trust. To establish that trust, you must respect patients' autonomy. Patients must be given sufficient information, in a way that they can understand, to enable them to exercise their right to make informed decisions about their care. This right is protected by law.

If consent is to be obtained by a doctor for any procedure, examination or investigation, then the patient must feel comfortable in their decision of informed consent. For informed consent to be viable, the patient must - as stated above - have sufficient information about the procedure they are about to undergo. Facts that they may wish to know might include:

  • details of the diagnosis, and prognosis, and the likely prognosis if the condition is left untreated;
  • uncertainties about the diagnosis including options for further investigation prior to treatment;
  • options for treatment or management of the condition, including the option not to treat;
  • the purpose of a proposed investigation or treatment; details of the procedures or therapies involved, including subsidiary treatment such as methods of pain relief; how the patient should prepare for the procedure;and details of what the patient might experience during or after the procedure including common and serious side effects;
  • for each option, explanations of the likely benefits and the probabilities of success; and discussion of any serious or frequently occurring risks, and of any lifestyle changes which may be caused by, or necessitated by, the treatment;
  • advice about whether a proposed treatment is experimental;
  • how and when the patient's condition and any side effects will be monitored or re-assessed;
  • the name of the doctor who will have overall responsibility for the treatment and, where appropriate, names of the senior members of his or her team;
  • whether doctors in training will be involved, and the extent to which students may be involved in an investigation or treatment;
  • a reminder that patients can change their minds about a decision at any time;
  • a reminder that patients have a right to seek a second opinion;
  • where applicable, details of costs or charges which the patient may have to meet.




2. Describe the concept of competence to give consent/refusal for overall treatment

Competence is defined to be "the quality of being adequately or well qualified physically and intellectually". Using this definition, there are



3. Describe what is meant by blood pressure, know expected values and have an overall view of how it is normally maintained:
Blood pressure is defined to be: "The pressure of blood against the walls of the main arteries". However, due to the changing nature of human blood pressure, the measurement of blood pressure is split into two parts: Systolic pressure and Diastolic pressure.
Systolic Pressure is the pressure reached when the ventricles are in systole (contraction), and the diastolic pressure is the pressure reached when the ventricles are in diastole (relaxation).
Blood pressure is measured in millimetres of mercury, and the clinical measurement is performed by a Sphygmomanometer and a stethoscope (shown below):

external image sp_st.jpg
external image 2652W.jpg
Figure 1
Figure 2
The Blood pressure is measured from the Brachial artery, as this is one of the easiest peripheral arteries to find, and circulation to the arm can be cut off for short periods of time.
Blood pressure is normally displayed in the form of systolic/diastolic, and the normal values are considered to be 120/80.
High blood pressure - Hypertension - in the UK is defined (in non-diabetics) to be a sustained systolic pressure of greater than or equal to 140/90. Classification of blood pressure groups is shown in the table below:

Table 1. Classification of BP levels (mmHg) in people without diabetes.
Category*
Systolic BP
Diastolic BP
Optimal
<120
<80
Normal
<130
<85
High normal
130-139
85-89
Mild hypertension
140-159
90-99
Moderate hypertension
160-179
100-109
Severe hypertension
>=180
>=110
Isolated systolic hypertension
>=140
<90
  • When systolic and diastolic readings fall into different categories, the higher BP category should apply.

To maintain blood pressure in the body, two factors must be considered: The condition of the heart, and the volume of fluid in the cardiovascular system.
The reasoning behind these factors can be analogous to a car. The car stops running if it either runs out of fuel, or the engine breaks. Thus the blood pressure in the body is maintained by the heart beating effectively and in its correct rhythm, and by the fluid levels in the body being maintained by a correct intake of fluids and management by homeostasis.
The Physiological mechanisms to maintain normal blood pressure are listed below:
  1. Autonomic nervous system responses
  2. Capillary shift mechanism
  3. Hormonal responses
  4. Kidney and fluid balance mechanisms

The autonomic nervous system is the most rapidly responding regulator of blood pressure and receives continuous information from the baroreceptors (pressure sensitive nerve endings) situated in the carotid sinus and the aortic arch. This information is relayed to the brainstem to the vasomotor centre (VMC). A decrease in blood pressure causes activation of the sympathetic nervous system resulting in increased contractility of the heart (beta receptors) and vasoconstriction of both the arterial and venous side of the circulation (alpha receptors).

The Capillary fluid shift mechanism refers to the exchange of fluid that occurs across the capillary membrane between the blood and the interstitial fluid. This fluid movement is controlled by the capillary blood pressure, the interstitial fluid pressure and the colloid osmotic pressure of the plasma. Low blood pressure results in fluid moving from the interstitial space into the circulation helping to restore blood volume and blood pressure.

Hormonal mechanisms exist both for lowering and raising blood pressure. They act in various ways including vasoconstriction, vasodilation and alteration of blood volume. The principal hormones raising blood pressure are:
(a) Adrenaline and noradrenaline secreted from the adrenal medulla in response to sympathetic nervous system stimulation. They increase cardiac output and cause vasoconstriction and act very rapidly.

(b) Renin and angiotensin production is increased in the kidney when stimulated by hypotension (figure 3). Angiotensin is converted in the lung to Angiotensin II, which is a potent vasoconstrictor. In addition these hormones stimulate the production of aldosterone from the adrenal cortex which decreases urinary fluid and electrolyte loss from the body.
Angiotensin_regulation_of_fluid_levels.JPG

This system is responsible for the long term maintenance of blood pressure but is also activated very rapidly in the presence of hypotension.

The kidneys help to regulate the blood pressure by increasing or decreasing the blood volume and also by the renin-angiotensin system described above. They are the most important organs for the longterm control of blood pressure.
In conclusion blood pressure is controlled by several physiological mechanisms acting in combination. They ensure that the pressure is maintained within normal limits by adapting their responses both in the short and long term to provide an adequate perfusion to the body tissues.

Other factors such as vascular resistance play a part in blood pressure, but with relevance to this scenario, the most important factors are the heart and volume of fluid.



4. Describe the nature, mechanism, possible causes and management of a “faint”.

Faint - also known as syncope - is caused by reduction in blood flow to the brain, resulting in a loss of consciousness through reduced oxygen supply to the brain tissue. The types of syncope can be categorised below:

  • Vasovagal syncope - This is the common faint associated with a stress response of the autonomic nervous system which can either suddenly lower the pulse rate, the blood pressure or both together. It is one of the neurally-mediated reflex syncopes.
  • Carotid sinus syncope - Also is associated with abnormal sensitivity to external pressure over the region of the nerve sensory organ at the bifurcation (branching) of the external and internal carotid arteries in the neck. This is also a reflex syncope.
  • Tussive syncope - Induced by coughing fits, also called larangeal syncope.
  • Micturition syncope - A faint during or shortly after urination. Also a reflex syncope.

Some of the other common medical conditions which may result in syncope are orthostatic hypotension (fall in blood pressure when standing) and Cardiac arrhythmia (heart rhythm problems).

Reflex syncopes (described above) are events which are caused by the following mechanism:

• The blood vessels leaving the heart have baroreceptors that detect a decrease in blood pressure (i.e. when a person is orthostatic for a prolonged period and blood pools in the legs)
• The baroreceptors send a message to the brain, which in turn sends a signal to the heart to increase the heart rate, and tighten up the blood vessels
• This process occurs constantly in all of us as we adapt to changes in posture
• In reflex syncope, an abnormal reflex occurs that results in withdrawal of the message that speeds up the heart and tightens up the vessels, often because of an overshoot in the reflex that compensates for the fall in blood pressure
• The resultant decrease in blood flow to the brain will result in dizziness or lightheadedness if mild, and progress to fainting or loss of consciousness if more severe

Management of a faint should be carried out as follows:
  • Lay the casualty down on his/her back
  • Raise and support the legs
  • Make sure that a good supply of fresh air is available – open a window if necessary
  • As they recover, reassure them and help them sit up gradually
  • Look for and treat any injury that has been sustained during falling



5. Describe why stitches would promote wound healing and prevent scarring.

Their are several methods used for primary closure of the skin. Stiches or sutures are the commonest form of primary closure and they are used to promote fast wound healing and to minimise scarring at a superficial level for the patient. The method for closure of wounds using suturing can be seen in the pictures below:

The edges of the
suturing.JPG



Definitions:

Autonomy - A patient's right to decide whether or not to undergo any medical intervention even where a refusal may result in harm to themselves or in their own death.

Informed Consent - Consent by a patient to a surgical or medical procedure or participation in a clinical study after achieving an understanding of the relevant medical facts and the risks involved.

(Definitions from Oxford Medical Dictionary and www.dictionary.com)

Sources:

First Aid Manual

http://www.gmc-uk.org/guidance/library/consent.asp - also in the GMC booklets given out in Freshers' Week

http://www.prodigy.nhs.uk

http://www.londoncardiac.ca/pages/vvs.htm

http://en.wikipedia.org/wiki/Fainting