Other influences on blood pressure
Blood pressure after a meal
After a meal, on the other hand, blood pressure is somewhat lower. The reason for this is that the human body is busy digesting and the digestive organs are therefore supplied with more blood. The blood volume of the body therefore decreases somewhat and so does the blood pressure. In order to avoid false results, blood pressure should not be measured immediately after a meal.
However, if the blood pressure drops sharply after a meal, this is called postprandial hypotension. This can result in dizziness, lightheadedness and an increased risk of falling. It usually affects older people with high blood pressure or people who have damaged a center in the brain that controls the autonomic nervous system – i.e. in diseases such as Parkinson’s, Shy-Drager syndrome or diabetes. The reason for this is that blood pressure during digestion cannot be maintained by the blood vessels in other parts of the body. Eating small meals that are low in carbohydrates can help.
Blood pressure and weather
It is often mistakenly assumed that high temperatures can lead to high blood pressure. In fact, the opposite is true: the high temperatures cause dilatation of the vessels and thus blood pressure drops. While hypotension is not dangerous for healthy people, it can cause serious problems for pregnant women and elderly people, as the supply of vital organs or the care of the child can no longer be guaranteed. If, on the other hand, the temperature drops, this becomes a problem, especially for hypertensive patients. The drop in temperature causes the vessels to contract further and the blood pressure rises, as a higher resistance has to be overcome.
Blood pressure and coffee
Caffeinated drinks should not be consumed before a blood pressure measurement, as they can increase blood pressure by 10-20 mmHg in the short term. A higher increase in blood pressure after coffee consumption can be observed especially in people who drink coffee only occasionally – but with more frequent caffeine consumption, a habituation effect sets in. The question of whether the consumption of caffeinated beverages increases blood pressure is controversial. A systematic review and meta-analysis (n=172,567) concluded that drinking more than three cups of coffee a day compared to one cup or less was not associated with an increased risk of hypertension. However, a slightly increased risk was found with consumption of 1-3 cups daily.
Blood pressure while lying down
Im Liegen ist der Blutdruck um 3-10 mmHg höher als im Sitzen. Aus diesem Grund gilt bei gesunden, mobilen Personen die Empfehlung, immer im Sitzen zu messen, um die Messergebnisse nicht zu verfälschen. Neben der Höhe des Blutdrucks ist allerdings auch seine Stabilität von großer Bedeutung. Eine Studie aus dem Jahr 2006 hat gezeigt, dass bei Personen, deren Blutdruck sowohl im Stehen als auch im Liegen ähnliche Druckwerte aufweist, gemessen an der Sterblichkeit, doppelt so vital waren als diejenigen Probanden, deren Blutdruck vom Liegen zum Stehen deutlich absank. Schlussfolgernd kann ein instabiler Blutdruck als Risikofaktor für Herz-Kreislauf-Erkrankungen angesehen werden.
Blood pressure and pulse
The HARVEST study found that 15% of hypertension patients had a heart rate over 85 beats and 27% had a heart rate over 80 beats per minute. In addition, a high heart rate was shown to be a risk factor for developing hypertension during the course of the study.
Heart rate variability (HRV), the variation in the time interval between two heartbeats, was also lower in hypertensives than in people with normal blood pressure levels. In addition, the likelihood of developing hypertension was higher when baseline HRV was lower than reference baseline.
In contrast, some hypertensives have a consistently low resting heart rate. The so-called “baroreceptor reflex” is responsible for this: if the blood pressure rises, the parasympathetic nervous system is stimulated via the vagus nerve, the sympathetic nervous system is inhibited and thus the heart rate is lowered due to the negative chronotropic effect. If, on the other hand, the blood pressure drops, the parasympathetic nervous system is inhibited and thus the heart rate is increased.