Raise your hands if you are fainting

Abstract

Giraffes do not raise their heads abruptly, they would faint if they did. A column of blood in their neck exerts a pressure of about 120 mm Hg and central arterial pressure cannot instantly increase by this amount as it should to prevent cerebral perfusion from dropping.1Editorial. The giraffe's parameter.Lancet. 1974; ii: 1491Google Scholar This type of postural hypotension (a fact lions must be aware of) is normal among giraffes. Imagine now that they had a trunk like the elephant. Could they avoid fainting by thrusting their proboscis in the air before quickly raising their head? Human beings with orthostatic hypotension, it seems, can do so with their arms. Measures recommended for postural hypotension include: compression of veins in the lower extremities (exercising leg muscles, wearing tight stockings); expansion of extracellular volume (high-salt diet, salt-retaining steroids); treatment with sympathomimetic amines (eg, ephedrine);2Adams RD Martin JB Faintness, syncope and seizures.in: Petersdorf RG Adams RD Braunwald E Isselbacher KJ Martin JB Wilson JD Harrison's principles of internal medicine. McGraw-Hill, New York1983: 76-82Google Scholar and abdominal compression.3Tanaka H Yamaguchi H Tamai H Treatment of orthostatic intolerance with inflatable abdominal band.Lancet. 1997; 349: 175Summary Full Text Full Text PDF PubMed Scopus (50) Google Scholar Might raising the arms, a simple manoeuvre hitherto not reported, be added to them, as the following case report suggests? An otherwise healthy man aged 42 years who was taking no drugs and had a history of mild postural hypotension (occasional transient dizziness and near-syncope on arising from sitting, squatting, or recumbency) was told to lie in a hot bath for 15 min and, to precipitate symptoms, to stand up rapidly, either with his arms raised, keeping them up for 15 s or after repeated exercising of his leg muscles (20 foot flexions and extensions and standing on and off his toes once upright). He stood up six times with intervals of 5 min on each of three days. Dizziness or near-fainting was invariably reported instantly or within seconds of standing up after exercising his legs, but did not occur when his arms were raised. In the latter posture he always reported a distinct awareness of his radial pulses. His heart rate increased slightly in both positions. Since then, in situations that cause him postural hypotension, he successfully uses this manoeuvre to prevent (or abort) symptoms. Physiologically, this approach can be thought of as a haemodynamic equivalent, in the upright position, of raising the legs of recumbent patients to treat hypotension or shock. Although the effect of raising the legs is not immediate and is ascribed to increasing venous return,4Sobel BE Roberts R Hypotension and syncope.in: Braunwald E Heart disease. Saunders, Philadelphia1988: 884-895Google Scholar it is likely that raising the arms, which contribute little venous return, instantly increases cerebral arterial pressure as a result of the higher column of blood in the arteries of the raised arms. Cerebral perfusion is enhanced at the expense of the arms in which the arteries are gradually drained (radial systolic surge is felt). Raising the arms provides a sort of endogenous counterpulsation, bridging the interval until cardiovascular compensating adjustments become effective. So, raise your arms if you are fainting.