How Do You Measure Oxygen (O₂) Saturation?

What is pulse rate?

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Pulse is the rhythmic expansion and contraction of the arteries as blood is pumped by the heart and which can be felt at certain locations of the body, most commonly the wrist (radial) and neck (carotid).

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Each pulsation represents a heartbeat, and the pulse rate is the number of heart beats per minute (bpm).

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Why measure pulse rate?

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A regular pulse indicates that your heart is effectively pumping blood throughout the body and our pulse rate can be reflective of our health in general such as physical fitness.

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In practice, it is most useful and the easiest to determine two features of the pulse:

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1. Pulse rate:

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At times, when the pulse is too high (tachycardia) or too low (bradycardia), it can be a sign of an underlying abnormality such as cardiovascular (heart) or thyroid problems.

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2. Pulse rhythm:

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Our heart (for the most part) should beat at a regular interval. When our heart beats irregularly this usually requires further investigation as it can be a sign of a rhythm abnormality of the heart.

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How do you measure pulse rate?

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To obtain an accurate pulse reading:

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1. Find a quiet and comfortable space:

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Choose a calm environment to minimize external influences on your pulse rate.

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2. Locate your pulse:

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Common pulse points include the wrist (radial artery) towards the thumb side (see below) and the neck (carotid artery).

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It is often easiest to use two to three fingertips (index, middle and fourth fingers) and applying light pressure at the site to feel the pulse.

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3. Count the beats:

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Using a timer or watch, count the number of beats you feel within a 60-second interval. Alternatively, count for 15 seconds and multiply by 4 to get your beats per minute.

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4. Ensure proper technique:

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Maintain a light touch when feeling for your pulse. Pressing too hard may obstruct blood flow, leading to inaccurate readings.

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5. Record your findings:

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Keep a log of your pulse rate, noting the time of day and any relevant activities or emotions. Regular monitoring helps identify patterns over time.

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What is a normal pulse rate?

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A normal resting pulse rate for adults typically falls between 60 and 100 bpm at rest. Athletes may have lower resting rates due to enhanced cardiovascular fitness.

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Remember, like blood pressure, pulse rate is dynamic and will go up and down depending on several factors including:

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• Age
• Body temperature
• Physical activity
• Pain
• Emotions and stress
• Medication
• Caffeine intake

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Understanding these factors can provide context to your pulse readings.

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Summary

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Monitoring your pulse can offer insights into cardiovascular fitness and help detect irregularities. If you notice persistent irregularities in your pulse rate consult a medical professional.

What is body temperature?

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Body temperature is one of the core 'observations' or 'vital signs' that reflects the balance between heat production and heat loss within the body. It is measured in degrees Celsius (°C) or Fahrenheit (°F).

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The average adult's normal body temperature hovers around 37 degrees Celsius (98.6 degrees Fahrenheit) but like blood pressure, individual variation exists with a range from 36.1°C (97°F) to 37.2°C (99°F).

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Temperature can also vary slightly depending on the time of day, activity level, and other factors. It is a useful marker to measure, especially when we are feeling unwell to confirm if there is fever. In some instances, our body temperature can drop too low and when extreme, this is called hypothermia.

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Why is it useful to measure body temperature?

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Measuring body temperature can help to:

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• ‍Detect an infection: When you have an infection, your body temperature will often rise. This is because your body is fighting off the infection and trying to raise the temperature of your body to make it more difficult for the bacteria or virus to grow.

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• ‍Identify other health problems: Sometimes, a high or low body temperature can be a sign of an underlying health problem, such as a thyroid disorder.

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How do you measure body temperature?

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There are several ways to measure your body temperature. The most common methods include:

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Oral thermometer:

This is one of the commonest types of thermometers. Place the thermometer under the tongue and with your mouth closed hold the thermometer in place until a reading is taken.

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Wait at least 15-30 minutes after eating or drinking hot/cold substances before taking an oral temperature.

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Rectal thermometer:

This is the most accurate type of thermometer, but it is not recommended for adults. Insert the probe gently into the rectum until the device beeps or the specified time elapses.

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Use a water-soluble lubricant (such as KY-Jelly).

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Axillary (armpit) thermometer:

‍This is a good option for children and babies. Place the thermometer under the armpit and hold the arm snugly against the body for the recommended time until the thermometer beeps.

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Keep the area as dry as possible when taking a measurement.

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Tympanic (ear) thermometer:

‍This is a quick and easy way to measure your temperature. Place the thermometer in the ear, click the button and hold it in place until it beeps.

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Pulling the ear gently can help straighten the ear canal and ensure a snug fit for an accurate reading.

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Infrared (forehead) thermometer:

This method is quick, non-invasive and suitable for children and adults. It is also useful when many measurements need to be taken quickly (e.g. in a screening setting). However, it may be less accurate than other forms of measurement. Point the thermometer at the forehead, click the button and wait until a reading is taken.
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Keep the forehead dry, free from sweat or hair for optimal results.

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Tips for accurate temperature readings

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1. Choose the right thermometer: different thermometers have specific uses, so choose the one most appropriate for the age group and situation.

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2. Follow manufacturer instructions: always adhere to the instructions provided with the thermometer as each device may have slightly different specifications.

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3. Rest before measurement: wait for at least 15 minutes after physical activity or consuming hot/cold substances before checking temperature.

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4. Consistent method: sticking to one method for consistency can help to monitor trends in body temperature over time.

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What is considered a fever?

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Fever: A body temperature of 38°C (100.4°F) or higher is indicative of a fever.

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Low-Grade Fever: some sources might use the term "low-grade fever" for temperatures slightly above the normal range but below 38°C (100.4°F).

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What is considered hypothermia?

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Hypothermia is when the body temperature drops dangerously low, to below 35°C (95°F).

Summary

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It is important to be aware that the method of measurement can affect the recorded temperature to a degree (not literally!). For example, oral, rectal, ear, and forehead temperature measurements may yield slightly different readings, however the cut-off ranges above for fever and hypothermia hold true.

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It can be helpful to be familiar with your own baseline temperature and recognize any significant deviations from your normal range.

Why is evidence-based medicine important?

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If you haven't already, take a read about evidence-based medicine in Part 1. In short, evidence-based medicine (EBM) is crucial for several reasons:

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Less guesswork, more certainty

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Evidence does not lie. It does not hold on to tradition or bias and it is not afraid to be wrong. If evidence emerges to the contrary of established medical thinking, this then becomes the new thinking. Antiquated, ineffective practices are thrown out with the adoption of safer, more effective practice. Evidence-based medicine is like a set of rules that everyone follows so there is standardisation and means you're more likely to get the same high-quality care no matter where you go.

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Better outcomes, ethical care

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Working on the principles of evidence-based medicine ensures that doctors make decisions based on the most recent and reliable scientific information. This way, you're less likely to get treatments that don't work or, even worse, harm you, upholding the ethical principles of medicine. Evidence-based medicine is about keeping patients safe and making sure the best care possible is offered which is of paramount importance.

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Pushing medical advancement

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The practice of evidence-based medicine serves as a catalyst for medical advancement. By promoting rigorous research and sound scientific practices, it fosters the continuous exploration of novel and innovative approaches to healthcare which contributes to enhanced patient care and better medical outcomes.

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Better resource allocation

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Healthcare resources like money and time are limited and so evidence-based medicine plays a crucial role in guiding the judicious allocation of these resources by focusing on treatments and practices that have been proven to work and are cost-effective.

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In essence, EBM is a powerful tool that elevates healthcare to a higher standard of evidence-driven decision-making, prioritizing patient well-being, ethical care, medical advancement, and efficient resource utilization.