The colour of a part depends upon the amount and distribution of blood in it, upon the general aeration of the blood, the local vigour of the circulation, or upon the escape of blood from the blood-vessels. When gentle pressure with the finger causes a temporary blanching of the compressed part, it shows that the blood is still within the vessels; when pressure upon the part makes no alteration in its colour, it shows that the blood is outside the vessels. In this way we distinguish between hyperemia and extravasation of blood.<Callout type="important" title="Important">Always check for signs of circulation before applying pressure.</Callout> Hypertemia, or excess of blood within the vessels, may be due to one of three causes: excess or enlargement of blood-vessels, dilatation of arterioles, venous obstruction or stasis. To distinguish between these conditions attention must be paid to the colour, the temperature, the presence of swelling, the sensation in the affected part, and also to the rapidity of flow of the blood in the vessels and to the history of the condition.<Callout type="risk" title="Risk">Incorrect diagnosis can lead to improper treatment.</Callout> The colour is an indication of the oxygenation of the blood; a bright colour indicating arterial hyperemia, and a dark colour venous hypereemia; but in general cyanosis even arterial hyperemia is livid in colour. An increase of local temperature always indicates arterial hyperemia, and local coldness is always an indication of retarded venous circulation.<Callout type="tip" title="Tip">Use the color changes to guide your diagnosis.</Callout> If the redness is associated with swelling, an attempt should be made to estimate their dependence one upon the other. Marked hypersemia may be quite unattended with appreciable swelling, as in blushing; it may be attended with slight swelling, as in cutaneous erysipelas; or associated with considerable swelling, as in abscess or in oedematous intertrigo.<Callout type="warning" title="Warning">Swelling can mask underlying conditions.</Callout> Where redness is one of the phenomena of inflammation, swelling will always be found with it; it may, however, be so little marked as not to be noticeable as enlargement of the part so much as in a certain increase in its tension, or consistence. Prolonged active hyperemia leads to increased growth of a part, and passive and obstructive venous hyperemia always causes swelling from oedema.<Callout type="important" title="Important">Monitor for signs of gangrene.</Callout> Further, a swelling may be wholly composed of enlarged vessels, which give it a colour, as in varicose veins. Greatly swollen parts may become hyperemic or even inflamed, as the result of friction or of dirt; the patches of intertrigo in connexion with large pendulous tumours, scrotal hernias, or the oedema of Bright's disease, afford illustrations of this.<Callout type="risk" title="Risk">Misdiagnosis can lead to complications.</Callout> To distinguish between these various associations of swelling and hyperemia, we must note, if possible, the order of succession of the two conditions, and the relative area of each. The rapidity with which the colour returns to a hypertemic part that has been blanched by temporary pressure with the finger is an important indication of the activity of the circulation: it is immediate in inflammation or varicose veins; it is rapid in great venous congestion; it is slow in oncoming gangrene or in the languid circulation of approaching death.<Callout type="tip" title="Tip">Check for pain or increased sensitivity with hyperemia.</Callout> Finally, the association of alteration of sensation with hyperemia is to be noted. Inflammatory hyperemia, and indeed nearly all active hypereemia, is attended with pain or increased sensitiveness. When, on the other hand, there is a combination of numbness, or loss of the normal acuteness of sensation, with hyperemia, it indicates a failure of the local processes of nutrition, unless indeed the two phenomena own one common cause in some affection of the nervous system; this will be shown by other signs, such as motor paralysis.<Callout type="warning" title="Warning">Numbness and loss of sensation can indicate serious underlying issues.</Callout> Extravasated blood in living tissues undergoes certain changes in colour which are familiar to us all in a common bruise, and by noting these colours, particularly the yellow, we can form some idea of the age of the extravasation. Where the extravasation is associated with the death of the tissues, being either a cause or a consequence of gangrene, these changes do not occur, but the part assumes a peculiar leaden hue; a greenish tint may be seen in places, but there is never the bright-yellow colour so characteristic of the later stage of a bruise. The marked flaccidity of the tissue, its insensibility and its coldness, are other evidences of the death of the part. {See Chap. XXIII.)
Key Takeaways
- Distinguish between hyperemia and extravasation by checking for changes in color after applying pressure.
- Monitor the rapidity of blood flow return to identify active or obstructive conditions.
- Note the association of pain, numbness, and swelling with underlying issues.
Practical Tips
- Use the color changes as a primary diagnostic tool when assessing injuries.
- Always consider the history and context of the patient's condition for accurate diagnosis.
- Be aware of the signs of gangrene to prevent further complications.
Warnings & Risks
- Incorrectly diagnosing conditions can lead to improper treatment and worsen outcomes.
- Swelling can mask underlying issues, making it harder to diagnose accurately.
- Numbness or loss of sensation should be taken seriously as a sign of potential serious injury.
Modern Application
While the techniques described in this chapter are rooted in historical practices, they still hold relevance for modern survival medicine. Understanding redness and lividity can help in quick diagnosis during emergencies, though modern tools like imaging may provide additional insights. The principles of careful observation and accurate assessment remain crucial.
Frequently Asked Questions
Q: How can I tell the difference between hyperemia and extravasation?
You can distinguish between hyperemia and extravasation by applying gentle pressure with your finger to see if the color returns immediately (hyperemia) or remains unchanged (extravasation).
Q: What are some signs of gangrene that I should look for?
Gangrene can be identified by a peculiar leaden hue, greenish tint, marked flaccidity of the tissue, insensibility, and coldness. These changes indicate the death of tissues.
Q: How does local temperature change help in diagnosing conditions?
An increase in local temperature always indicates arterial hyperemia, while local coldness is an indication of retarded venous circulation, helping to differentiate between these conditions.