What factors can affect pulse and respiratory rates?
Being able to take an accurate pulse and respiratory rate is a core skill for first aiders. There are a number of factors which can affect pulse and respiratory rates, we’ll take a look at some of these in this blog post.
We can feel this ‘pulse’ where the arteries pass over a solid structure like bone – the wrist is a good example. The pulse – its rate (the number of times per minute we can feel the pulse), its strength (whether it’s full and ‘bounding’ or weak and ‘thready’) and its rhythm (regular or irregular) – can tell us a lot about a casualty.
The pulse rate can be affected by:
- Age – young children commonly have a higher pulse rate, in the elderly it may be slower.
- Exercise – taking part in exercise will raise the pulse rate. Trained athletes may have a slower ‘resting heart rate’.
- Disease – illness places pressure on the body, leading to an increased heart rate
- Drugs – depending on the drug, it can speed up or slow down the heart rate
- Body Temperature – cold will initially raise the pulse rate, before slowing dramatically. Fever (pyrexia) will cause an increase in pulse rate.
- Posture – a patient lying flat will have a slower heart rate than when sat or stood.
- Stress – stress increases the heart rate due to adrenaline/epinephrine release.
The rate and character of the respirations gives us important insights into people’s general health status. In addition, breathlessness is a very distressing symptom for many people, and it’s important that to identify problems early and deal with them.
A number of factors can influence the respiration rate, such as:
- Age – younger children generally have higher oxygen demands and therefore breath faster
- Pain – pain will cause an increase in respiration rate
- Emotion – emotion will cause an increase in respiration rate
- Resistance from air passages – increased resistance (e.g. in asthma) prevents as much air entering the lungs during each cycle. The demand for oxygen will then increase, increasing the respiration rate.
- Fever – fever increases the body’s demand for oxygen, increasing the respiration rate
- Elasticity of the lungs – the less elastic the lungs, the less air can enter the lungs each cycle, increasing the respiration rate. Chemical changes – chemical changes in the body, caused by hypoxia, metabolic disorders or medications / drugs, can cause the respiration rate to increase or decrease, depending on the stimulus