Page 30 - Medicine and Surgery

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26 Chapter 2: Cardiovascular system

pressure of the venules is low. Any remaining interstitial oxygenation. This may be a result of blood bypassing
fluid is then returned to the circulation via the lymphatic the lungs (right to left shunting) or due to severe lung
system. disease.
Mechanismsofcardiovascularoedemaincludethefol-
lowing:
The arterial pulse
Raised venous pressure raising the hydrostatic pres-

sure at the venous end of the capillary bed (right ven- The pulse should be palpated at the radial and carotid
tricularfailure,pericardialconstriction,venacavalob- artery looking for the following features:
struction). Therateisnormallycountedover15secondsandmul-
Salt and water retention occurring in heart failure, tiplied by 4. The normal pulse is defined as a rate be-

which increases the circulating blood volume with tween 60 and 100 beats per minute. Outside this range
pooling on the venous side again raising the hydro- it is described as either a bradycardia or a tachycardia.
static pressure. The rhythm is either regular, regularly irregular, i.e.
The liver congestion that occurs in right-sided heart irregular but with a pattern, or irregularly irregular,

failure may reduce hepatic function, including albu- which is suggestive of atrial fibrillation.
min production. Albumin is the major factor respon- The character and volume of the pulse are normally
sible for the generation of the colloid osmotic pressure assessedatthebrachialorcarotidartery.Characterand
that returns the tissue fluid to the vasculature. A drop volume felt at the carotid may be described according
in albumin therefore results in an accumulation of to the waveform palpated (see Fig. 2.2).
oedema. Pulse delay is a delay in the pulsation felt between two
Oedema is described as pitting (an indentation or pit pulses. Radio-femoral delay is suggestive of coarcta-
is left after pressing with a thumb for several seconds) tion of the aorta, the lesion being just distal to the
or nonpitting. Cardiac oedema is pitting unless long origin of the subclavian artery (at the point where the
standing when secondary changes in the lymphatics may ductus arteriosus joined the aorta). Radio-radial de-
cause a nonpitting oedema. Distribution is dependent lay suggests arterial occlusion due to an aneurysm or
on the patient. Patients who are confined to bed develop atherosclerotic plaque.
oedema around the sacral area rather than the classical
ankle and lower leg distribution. Pleural effusions and Jugular venous pressure
ascites may develop in severe failure.
The internal jugular vein is most easily seen with the pa-
tient reclining (usually at 45˚), with the head supported
Cyanosis
and the neck muscles relaxed and in good lighting con-
Cyanosis is a blue discolouration of the skin and mu- ditions. The jugular vein runs medial to the sternomas-
cous membranes. It is due to the presence of desaturated toid muscle in the upper third of the neck, behind it
haemoglobin and becomes visible when levels rise above in the middle third and between the two heads of ster-
5 g/dL. Cyanosis is not present in very anaemic patients nocleidomastoid in the lower third. It is differentiated
due to the low haemoglobin levels. Cyanosis is divided from the carotid pulse by its double waveform, it is non-
into two categories: palpable, it is occluded by pressure and pressure on the
Peripheral cyanosis, which is seen in the fingertips and liver causes a rise in the level of the pulsation (hepato-

peripheries. When occurring without central cyanosis jugular reflex). The jugular waveform and pressure give
it is due to poor perfusion, as the sluggish circulation information about the pressures within the right atrium
leads to increased desaturation of haemoglobin. This as there are no valves separating the atrium and the in-
may be as a result of normal vasoconstriction in the ternal jugular vein (see Fig. 2.3).
cold, poor peripheral circulation or a poor cardiac The height of the jugular venous pressure (JVP) is as-
output. sessed as the vertical height from the sternal angle to the
Central cyanosis also affects the warm mucous mem- point at which the JVP is seen. A height of greater than

branes such as the tongue. It is a result of failure of 3cmrepresents an abnormal increase in filling pressure