Reading the vital signs of a patient is the first proper step you can make to ensure adequate medical assistance is provided. In today’s article, we will discuss the vital signs, how to read them, and what information they can provide, to help us better treat a patient.
A lot of people have trouble saying “sphygmomanometer” If you’re one of them, don’t feel bad. I had been using one for a long time before I knew that the technical name for a blood pressure cuff was a sphygmomanometer.
At the scene of an accident one night, a bystander decided he needed one more than I did. When I was filling out the theft report, I realized I couldn’t even pronounce it, let alone spell it. If your tongue trips over the correct pronunciation (sphyg-MO-ma-nom-e-ter), no one cares. Fancy words don’t help when it hits the fan.
Understanding how to read vital signs
There are four things that will tell you the state of wellbeing of anyone who is seriously ill or injured. They are pulse, respiration, blood pressure, and temperature. These are known as the vital signs. Three vital signs can be measured with your eyeballs and a watch, but one, blood pressure, requires the sphygmomanometer and stethoscope.
A blood pressure cuff is a very simple device. It’s a cloth-covered air bladder with two rubber tubes attached. One tube is connected to a rubber bulb. The bulb has a simple thumbscrew valve that is closed while you inflate the cuff, and open while you deflate it.
A second tube is connected to a gauge. The gauge has a dial calibrated in millimeters of mercury (mm Hg.), usually from 20 to 300 mm HG. in 10 mm increments. A second type of cuff incorporates the gauge and bulb on one tube, rather than two — a feature that is very convenient in many cases.
The cuff does nothing more than providing the means to momentarily shut off the blood flow through an artery so the high point and low point of blood pressure can be measured, and changes in blood pressure can be monitored over a period of time.
Using a sphygmomanometer
Normally a blood pressure reading is taken by placing a blood pressure cuff and stethoscope over the brachial artery. This artery is convenient and readily accessible. The brachial is located close to the surface of the skin on the inside center of both arms at the elbow.
The cuff is wrapped around the arm about an inch or so above the elbow (hook & loop fastening is commonly used to keep the cuff in place). The valve on the rubber bulb is closed, and the bulb is squeezed to inflate the cuff. When the pressure in the cuff exceeds the highest pressure in the artery, the artery is squeezed shut, and no blood flows downstream.
You can tell when the cuff pressure exceeds the highest blood pressure by watching the needle on your gauge. As you inflate the cuff, you will notice that the needle bounces. This tells you that there is still insufficient pressure in the cuff to shut off the highest blood pressure.
The bounce is caused by the heart pumping blood at a higher pressure than the pressure from your cuff. Keep pumping. When the pressure from the cuff is higher than the blood pressure, the bounce will stop because no blood is flowing through the artery.
Usually, the pressure in the cuff will exceed blood pressure about 150 to 200 mm Hg. You will now need a stethoscope.
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Using a stethoscope
A stethoscope is a listening device. It’s handy for listening to other things, such as lung sounds, but we’ll confine this to blood pressure only.
The stethoscope is just two pieces of hollow rubber tubing. The two tubes are joined together at one end in a circular metal housing. Most modern scopes offer a choice of a large (approx. 1½ ” dia.) and a small (approx. 1″ dia.) diaphragm.
This diaphragm is placed over the brachial artery when measuring blood pressure. To choose between the large or small diaphragm, just rotate the housing.
Towards the opposite end of the stethoscope are the earpieces. Two curved metal tubes provide enough spring tension to allow you to insert both earpieces in your ears without having to use your hands to hold them there. A choice of plastic or rubber replacement earpieces and spare diaphragms are also included in your kit.
To check vital signs, measure respiration by counting the number of times per minute, the chest rises and falls. Usually, an adult breathes 12 to 20 times per minute.
Measure the pulse by placing a finger on any of several pulse points, usually the carotid artery on either side of the neck, or the radial pulse on the wrist. Count the number of beats by looking at your watch for 15 seconds and then multiply by four to obtain the beats per minute. In the normal adult, the pulse should be between 60 and 80 beats per minute.
Checking the patient’s temperature
The temperature should be 98.6 F. (37 C.), but in the field, just place your hand on the victim’s forehead and feel for extreme heat or cold. If time permits, use a thermometer by placing it under the tongue for at least three minutes.
If you fail to detect breathing or a pulse, check your ABCs: Airway, Breathing, and Circulation, and be prepared to do CPR (Cardiopulmonary resuscitation). This leaves the remaining vital sign, commonly called “B.P.,” but a little explanation is in order.
Force Of Blood
Blood pressure is the force that circulating blood exerts against the walls of arteries. The heart muscle contracts to send out a spurt of oxygen-saturated blood to all the organs of your body. It then relaxes for a moment while the heart fills with more blood. Then it squeezes again and sends out another shot of blood.
It is this rhythmic motion of the heart that enables us to feel and count the beats of the heart by placing a finger on the neck artery or wrist artery and measuring beats per minute. Counting a pulse rate only tells you that there is blood pressure, but it won’t tell you if the pressure is stable or going up or going down. You need the cuff and stethoscope for that.
We’re all going to die. It may be slow and expected, as in a long bout with cancer, or it may be very fast and unexpected, but regardless, the process will be the same. Think of it as a journey down a highway from life to death. Fortunately, this journey can be interrupted at any point if you recognize the signs and symptoms.
Being able to measure changes in blood pressure is a vital indication of how far down the highway your victim has traveled.
First, the victim loses the ability to communicate. They become less aware of their surroundings and do not seek to express themselves.
The victim then loses consciousness. They are completely unaware of their surroundings and cannot be aroused.
As the victim slips deeper into unconsciousness, the muscles relax, and the tongue falls back against the throat, causing airway obstruction. Within a minute or two, the victim is in respiratory arrest.
In another minute or two, the heart stops because it cannot function without oxygen from the lungs. The victim is now in cardiac arrest. This is the point of clinical death.
All the vital organs are now starving for blood and oxygen, and the most vulnerable organ is the brain. Brain cells begin to die, and within a very short time (4 to 6 minutes is a rule of thumb), enough cells have died to cause biological death or complete death of the organism.
Many things cause injuries, but very few are immediately life-threatening. The four primary threats to life are:
- an obstructed airway,
- respiratory arrest,
- cardiac arrest, and,
- severe bleeding.
If your victim is unconscious, do not forget the all-important ABCs. Check the Airway, Breathing, and Circulation and control any bleeding. Now you’re ready to measure the high and low points of blood pressure.
When the heart contracts, the pressure goes up, and when it relaxes, the pressure drops momentarily. Because of this squeeze/contract cycle (slightly faster than once per second), the entire volume of blood, about 12 pints, is circulated about once per minute in a somewhat jerky fashion. The highest point of blood pressure is called “systole,” and the lowest point is called “diastole.” It is the cuff and stethoscope that allow you to hear systole, the highest pressure, and diastole, the low point when the system returns to its resting level.
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Taking Blood Pressure
Wrap the inflatable cuff around the victim’s upper arm with the lower edge of the cuff about an inch above the elbow. The arrow on the cuff should be centered over the brachial artery. Place the diaphragm of your stethoscope over the brachial artery and listen to fin the pulsations. Close the valve on the bulb and quickly inflate the cuff to sufficient pressure to shut off the highest pressure in the artery.
The needle on the pressure gauge will stop bouncing with every pulse beat, usually about 150 to 200 mm Hg. With the stethoscope still in place over the brachial artery, slowly release the pressure in the cuff using the valve on the bulb. Keep your eyes on that gauge!
Release pressure slowly, about 2 to 2 mm Hg. per second.
As the pressure in the cuff falls, at some point, the highest arterial pressure will again equal cuff pressure. At this point, you will hear the start of a series of thumps through your stethoscope as blood resumes flowing.
The first thump is the systolic (highest) blood pressure. Note the reading on the pressure gauge. This is the first of two measurements.
Continue to listen carefully as you let more pressure out of the cuff. Keep watching the gauge. Soon the rhythmic pulses will grow very faint or disappear altogether. The pressure in your cuff has dropped below the lowest pressure in the artery. Note the position of the needle on the gauge.
You have just read the low point, or diastolic pressure, for your second and last reading. Deflate the cuff completely, but you may want to leave it in place on the arm so that you can recheck blood pressure at frequent intervals without having to put the cuff back on each time.
Blood pressure is expressed as a fraction with the systolic pressure placed over the diastolic pressure. If the first thump you heard through your stethoscope occurred when the needle was at 120 mm Hg. (systolic pressure) and at 80 mm Hg. you couldn’t hear the pulse beats at all (diastolic pressure) it would be written as “120/80” and stated as “120 over 80.”
This is a very important point. One blood pressure reading by itself is not very useful, especially if you don’t know what your victim’s normal blood pressure is. It is the pattern of changes in blood pressure, measured over time, that is crucial. Take frequent readings and write them down along with the time. Do not try to remember them.
Many of you have been in critical situations before, and you undoubtedly know how five minutes can seem like an hour. Keep a small notebook and pencil in the bag that comes with your blood pressure cuff (Pencil, because it will not freeze, melt, or clog up when you need it).
What is a pattern of changes in blood pressure?
If you take three readings over a 20-minute period and get 120/80, 119/82, and 121/78, you don’t have to worry. Check the other three vital signs just to be sure, but these minor variations are caused by any number of things such as background noise, movement, etc.
If you take three consecutive readings over 20 minutes and get 120/80, then 100/75, and your final reading is 90/65, you are facing a radical drop in blood pressure. In this example, let’s just say that you have been checking the other vitals and see an increase in pulse rate, cool and clammy skin, and rapid but shallow respirations. Your victim is probably going into shock, and you need help immediately.
Here is another crucial point, however. Do not try to “diagnose” from the field!
If you have a victim showing noticeable changes in blood pressure — whether it is steadily rising, falling, or just jumping all over the gauge —get help immediately. Call your local Emergency Medical Services and get the victim assistance as soon as possible. Unless you’re extremely skilled, have a lot of equipment with you, and are incredibly lucky, there is little you can do by yourself.
The odds are greater that you will encounter a threat to your survival or your family’s survival through accident than any other means. The best preppers and survivalists have a determination of spirit coupled with a good grounding in basics. Having a cuff and stethoscope in your med bag, coupled with the knowledge of how to use them to measure vital signs, is part of that essential grounding in basic skills that every one of us should know.
These items are readily available through any medical supply house. They weigh just a few ounces each, take very little space in your pack, and they are surprisingly rugged. There are many fine electronic cuffs on the market, but they are not suitable for field use. They’re vulnerable to heat, dust, moisture, and they require a power source.
Also read: Learning To Recognize and Treating Dangerous Heat Disorders
A final word
It is important to remember the following when checking the vital signs since this information can give valuable aid in providing proper medical care.
Normal Vital Signs Reading:
- Adults – 60-80 per minute
- Children – 80-160 per minute
- Infants – 80-160 per minute with an average of 120
- Adults – 12-20 per minute
- Children – 18-26 per minute
- Infants – 25-36 per minute with an average of 120
- 98.6 F or 37C
- Systolic: 100 mm Hg. plus age (up to 150 mm Hg.)
- Diastolic: 65-90 mm Hg.
- Systolic and Diastolic: 8-10 mm Hg. lower than in a male of the same age
Signs and Symptoms of Shock
- Restlessness and anxiety
- Extreme thirst
- Nausea and/or vomiting
- Cold, clammy skin
- Weak, rapid pulse
- Shallow, rapid breathing
- Changes in state of consciousness
- Drop in blood pressure
No matter what situation you may find yourself in, just remember, after the battle, you still have to take care of your casualties.
This article has been written by James H. Redford MD for Prepper’s Will.
Useful resources to check out:
Knowledge to survive any medical crisis situation
Survival Lessons from the 1880s Everyone Should Know
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