Often, the very first thing which will be done to examine your body is to record your vital signs. There
are four signs that are easy to measure which give a large amount of important information: heart rate (pulse), rate of
breathing (respirations), blood pressure, and body temperature. Usually, the vital signs are taken by a nurse or medical
technician in the waiting area before your physician sees you and are recorded for the doctor to review.
The vital signs are measurements which are easily recognized and interpreted by all medical personnel.
They provide a quick assessment of how sick someone is and how urgently they need medical care. This is especially
useful in the emergency room where patients are treated according to who is in need of the most urgent care and not on a
firstcome, first-serve basis. For example, someone with a very high heart rate and a very low blood pressure could be
bleeding internally and require immediate attention.
If a person is critically ill and in danger of dying, he or she should be seen and treated before
someone who has a sprained ankle. This priority system for treating patients (called "triage") is not always
popular with the patients who have to wait.
By looking at vital signs, a doctor can tell whether the patient is "stable" and will not be
harmed by waiting, or "unstable" and in need of immediate life-saving measures. The vital signs are also an
inexpensive way to screen for a wide variety of medical diseases.
All screening tests have advantages and disadvantages. The advantages are that taking the vital signs is
quick, painless and cheap. The major disadvantage is that the information obtained is often very general and rarely
gives the specific cause of the problem. In other words, the vital signs are good at telling if something serious is
going on, but usually not too good at telling exactly what is wrong.
- Heart Rate and Rhythm:
In assessing the beating of the heart, there are two primary concerns: the rate at
which the heart is beating and the rhythm with which the heart beats. We all know that the heart's function is to pump
blood to the rest of the body in order to supply oxygen and nutrients while removing carbon dioxide and other wastes.
It makes sense, therefore, that the faster the heart is beating, the more blood is being pumped to the body.
Conversely, the opposite is also true.
Certain heart rates can be dangerous. If the heart is beating too slowly there is a danger that the body will not get
enough oxygen and nutrients, or that it will not be able to remove enough carbon dioxide and other wastes. On the
other hand, if the heart is beating too fast, the pump is having to work too hard and may need more oxygen than can be
supplied. This places parts of the heart muscle in danger of dying from lack of oxygen.
What is a normal, resting heart rate? That depends on the person's age. It is said that the normal adult heart rate is
72-80 beats per minute. This is true for most resting adults; however, children have heart rates which are faster than
adults and a newborn baby has a normal, resting heart rate of 120-160 beats per minute! Athletes who are in good
physical condition may have a normal heart rate of 50-60.
The maximum safe heart rate is an important concept because at rates above this safe maximum the heart can be in great
danger. The highest safe heart rate is determined by the formula: person's age subtracted from 220 = maximum safe
heart rate. It is also helpful to know that the heart rate which is best for beneficial aerobic exercise is 75-80% of
the maximum safe heart rate. There is no set minimum safe heart rate, but slow heart rates are determined to be normal
or not based on associated symptoms. If a person with a slow heart rate feels weak and tired, their heart rate may not
be fast enough to pump blood to their entire body (this could also be due to a blood pressure which is too low). In
extreme circumstances, a very slow heart rate will cause a person to lose consciousness because the brain is not
receiving enough oxygen to "stay awake".
Some Factors Which Increase Heart Rate:
- Body temperature: In general, the heart rate increases 10 beats per minute for every one degree
Fahrenheit which the body temperature increases. So, a person with a fever will have a faster heart rate than a
person without a fever.
- Anxiety: When a person is afraid, the nervous system is more aroused than normal and is preparing for
any emergency that might come along. The brain sends signals to the heart to make it beat faster so the body will
have enough oxygen to respond to any situation.
- Pain: Pain generally increases a person's anxiety level, thereby causing the heart rate to increase.
- Exercise: Any person who is exercising is using more oxygen and producing more carbon dioxide than they
are when resting, so they need more blood flowing in their body to meet these increased demands. Naturally, the heart
rate increases to help supply the extra blood that is needed by the rest of the body.
- Hyperthyroidism: The thyroid gland is a gland located below the Adam's apple in the neck. It secretes
hormones that determine how much and how fast energy is used by the body. This is called the body's metabolic rate
and it is mostly determined by the level of thyroid hormone in the blood. If this hormonal level rises, as it can
with some diseases, it causes the body to accelerate all of its functions including the heart rate.
- Anemia: Anemia is when there are not enough red blood cells in the blood to carry oxygen to the body,
and is caused by many diseases. In this condition, the heart compensates by pumping more blood; therefore, the heart
rate increases.
- Medications: Many medications increase the heart rate, either directly by acting on the heart itself,
or indirectly by affecting the brain or other organs.
Some Factors Which Decrease the Heart Rate:
- Sleep/Rest: Sleeping people generally have heart rates that are slower than when they are awake. Taking
the pulse of someone who lives in your house while they are sitting in front of the television and then taking it
again after they go to sleep will prove this point.
- Organic Heart Disease: The heart rate is regulated by electric signals which come from the top of the
heart and spread out along special channels to all of the heart muscle. When the heart muscle becomes damaged or
diseased, the signal for it to beat may not be generated or may be improperly transmitted, causing the rate to slow
down.
- Hypothyroidism: In the same way that too much thyroid hormone can speed up the body's metabolic rate,
too little hormone from the thyroid gland can slow down the metabolic rate so much that the heart slows down also.
- Medications: Many medications can slow down the heart rate. In fact, many of the medicines used to
treat irregular heart rhythms also have the effect of slowing the heart.
TAKING THE PULSE:
Where on my body can my doctor feel my pulse, and why would she or he want to feel it in different
places? There are many places where the pulse can be felt, but the most common is the wrist. Others sites include:
beside the eyes in the temples, in the neck on either side of the trachea (wind-pipe), under the arm, in the fold of
the elbow, in the groin, behind the knee, on top of the feet, and on the inside of the ankle just below where the bone
of the shin ends. [ Figure 3A ]
The easiest place to take the pulse is to feel for it on the wrist. To take the heart rate, press over
the correct places with the pad of your index and middle finger until you feel pulsations. Count the number of beats
that you feel in one minute, or count the number of beats that you feel in 15 seconds and multiply this by four to get
the rate per minute. Do not use your thumb since it has a pulse of its own which is often felt.
Feeling the pulse at the same place on both sides of the body tells the doctor that the arteries on
both sides are the same and that both have blood flowing through them.
Comparing the pulse in the arm and leg will help the physician to determine if there is a blockage or
constriction in the main artery which connects the upper and lower halves of the body. By feeling the pulse in the
legs, the physician can tell if the circulation in the feet is adequate. In many patients with poor circulation, for
example, the pulses cannot be felt in the feet and can only be detected with a special instrument such as
ultrasound.
The Heart Rhythm: There are three basic kinds of heart rhythms: one normal and two abnormal. The
first is regular and is the only heart rhythm which is considered normal. In a regular heart rhythm, the time between
each beat is the same, similar to the ticking of a clock. The first of the two abnormal heart rhythms is called
regularly irregular. In this rhythm, the time between each beat is not the same, but there is a pattern to the rhythm
which repeats itself, just like there is a pattern to the rhythm of a waltz. Next, there is the irregularly irregular
heart rhythm. In this rhythm, the beats are not separated by the same amount of time, and there is no pattern at all to
the beats.
We will not discuss the different causes of all these rhythms because they are very complex. Suffice
it to say that all abnormal rhythms deserve careful evaluation because they can be dangerous; however, most are
treatable.
- The Breathing Rate (Respiration):
There are many similarities between the heart rate and the rate of
breathing. As the heart serves as the pump which moves the blood through the body, the lungs serve the purpose of
regulating the gases (oxygen and carbon dioxide) which are dissolved in the blood. When the heart beats fast to supply
more oxygen and remove more carbon dioxide, the lungs have to exchange more air with the atmosphere in order for more
oxygen and carbon dioxide to enter and leave the body. Consequently, most of the time, the heart rate and breathing
rate increase decrease together.
HOW TO TAKE THE BREATHING RATE:
Watch a person breathe and count the times that their chest rises during a minute. You can also count
the times the chest rises during 15 seconds and multiply by four just as you did with the heart rate. It is often
important that the person not know that you are counting each breath because they will become aware of their
breathing, and their breathing rate will usually increase. Experienced nurses will count the breathing rate during the
pulse or temperature measurement without the patient ever knowing that this is going on.
So what is a normal breathing rate, and what controls the rate at which one breathes? It is said that
a normal adult with healthy lungs breathes 12-20 times a minute. Just as the normal heart rate is faster in children,
so is the normal breathing rate. There are two factors which control the amount of air which is exchanged with the
atmosphere: the level of oxygen in the blood and the level of carbon dioxide in the blood. Both of these levels are
sensed by the brain on a minute to minute basis, and adjustments are made in the rate and depth of breathing to keep
these levels constant.
A person breathes in oxygen and exhales carbon dioxide. Without this oxygen, our brain and other
organs would not be able to function. After the oxygen is used by the body, it is turned into carbon dioxide which is
an acid and should not stay in the body. In order for the carbon dioxide to be exhaled, the acid must cross over from
the blood back into the lungs and out of the body.
The exhalation of carbon dioxide from the body to clear the blood of acid build-up is the main factor
which controls our rate of breathing -- the higher the level of carbon dioxide, the faster we breathe to remove it. At
the rate of breathing which gets rid of enough carbon dioxide, we are already moving enough air into and out of our
lungs to provide adequate oxygen. Thus, the oxygen level in our blood does not directly control our rate of breathing.
However, in people with certain lung diseases (i.e. emphysema), enough acid has built up in their bodies that their
brain has begun to ignore carbon dioxide as a stimulus to breathe. These people have a rate of breathing which is
controlled directly by the level of oxygen in their blood -- when the level gets low, they breathe faster.
There is no set maximum or minimum safe rate of breathing. A person who is exercising vigorously may
breathe 40-50 times per minute, while one who is asleep may breathe 10-12 times per minute. It is true, however, that
the faster you breathe, the more energy it takes to breathe and the more tired your muscles for breathing will become.
A person who is breathing extremely fast is in danger of tiring out his or her muscles for breathing and may stop
breathing altogether. On the other hand, a person who is breathing too slowly is likely not getting rid of enough acid
and may not even be supplying the blood with enough oxygen.
Some Factors Which Increase the Breathing Rate:
Many of the factors which increase the heart rate also increase the breathing rate such as anxiety,
fever, pain, exercise and hyperthyroidism.
In addition, diseases which cause the body to produce more acid require an increased rate of breathing
to rid the body of the extra acid. These include uncontrolled diabetes, kidney disease, infection, ingestion of certain
poisons, drug overdosing, starvation, diarrhea, sickle cell anemia and many others.
Some Factors Which Decrease the Breathing Rate:
Many of the factors which decrease the heart rate also decrease the breathing rate such as sleep and
certain medications. Many drugs, such as powerful pain killers and alcohol, can reduce the rate of breathing to
dangerously low rates.
When the lungs move less air in and out, acid builds up in the blood. Usually, this is not good;
however, this can be used by the body to make up for when there is not enough acid in the blood. For instance, while
vomiting causes a person to lose a significant amount of stomach acid, the body can slow the rate of breathing thereby
increasing the amount of acid in the blood. Additional factors which decrease the rate of breathing include excess of
certain body hormones, excessive antacid ingestion, kidney failure, and even some cancers.
Rhythm and depth of breathing: It is normal to breathe with regular rhythm and to take breaths at
regular intervals. Big breaths and small breaths generally waste too much energy and are not an efficient way of
exchanging gas into and out of the lungs. For this reason, the brain regulates both the rate and the depth of
breathing to control the total amount of air which the lungs use.
In certain diseases or injuries, the rhythm of breathing can be altered significantly. For example,
when a person has fractured some ribs and the bones are poking into the lungs, it hurts to breathe. Naturally, the
brain compensates, and the breathing becomes shallow to decrease the pain but faster to keep the total volume of air
exchanged the same. Other abnormal rhythms are seen in certain head injuries when patients usually breathe both
rapidly and deeply.
Finally, here's a quick way which doctors use to determine how much energy a person is using to
breathe. The diaphragm (a powerful muscle which separates the chest from the abdomen) is responsible for most of the
effort of breathing. When a person needs to breathe faster and deeper, other muscles join in to help. These include
the abdominal muscles, some of the muscles in between the ribs, and some of the neck muscles. Together, these are
called the accessory muscles of breathing. When they are being used, they may indicate that the diaphragm is having
to work very hard to breathe, and, with prolonged use, it may stop altogether. People cannot breathe for long periods
of time with their accessory muscles and need rapid treatment to assist them in breathing more easily. However, some
patients with chronic lung diseases (such as emphysema) may have extra-strong accessory muscles and are able to use
them for extended periods without stopping breathing altogether.
- The Blood Pressure:
Remember that the heart, which is a muscle composed of four chambers, pumps blood to
supply oxygen and nutrients to the body while the lungs remove carbon dioxide and other wastes from the body. The
heart pumps blood in two different circuits, one of which is under high pressure and one of which is under low
pressure. The left side of the heart pumps blood to most of the body and powers the high pressure circuit. The right
side of the heart pumps blood to the lungs and powers the low pressure circuit.
In measuring the blood pressure, the doctor is measuring the pressure in the high pressure circuit. The blood pressure
is recorded as two numbers: one which is usually greater than one hundred, and one usually less than one hundred. For
example, a typical adult blood pressure would be 120/80. The top number is called the systolic pressure and the
bottom number is called the diastolic pressure. Usually the blood pressure is measured in the arm, using a
blood pressure cuff (sphygmomanometer) and stethoscope. It can also be measured at both the thigh and calf.
The high number of the blood pressure measures the pressure in the arteries during the peak of the heart's contraction
(while blood is pumped out of the left side of the heart), and the low number measures the pressure in the arteries
while the heart is resting. The pressure in the arteries is always somewhere in between the high and low numbers and
never falls to zero. This constant pressure causes the blood to move forward without stopping.
The heart needs to generate enough pressure to adequately supply the body because too little pressure will cause the
blood to move so slowly that organs will not function properly. Too much pressure causes the heart to work harder and
can even cause "blowouts" in some of the vessels or heart failure. In some kinds of strokes, brain tissue is
damaged when blood vessels burst under high pressure. The brain regulates blood pressure minute by minute by causing
the arteries and veins to either clamp down or relax, thereby regulating the body's blood pressure. The pressure can
also be altered by the rate and the force of the heart beat.
In assessing the blood pressure as one of the vital signs, only very high and very low pressures are of immediate
concern. However, the blood pressure measurement also doubles as a screening test for people with unknown,
long-standing high blood pressure which is not immediately dangerous but needs to be treated.
High Blood Pressure: When a patient has a diastolic blood pressure (the lower number) which is greater than 90
on multiple recordings, treatment is usually necessary. If the systolic blood pressure (the higher number) is
repeatedly measured to be greater than 160, treatment is also usually necessary. Patients with untreated high blood
pressures are more likely to experience heart attacks, strokes, and kidney failure.
Dangerously Low Blood Pressure: Generally, low blood pressure without the symptoms of weakness or dizziness is
not a problem. When a person is sick, however, their blood pressure can become so dangerously low that their organs do
not get enough blood. Very low blood pressure may cause people to feel dizzy and even to faint. When the blood pressure
is this low, the brain is not getting enough oxygen to stay awake, and the kidneys are not getting blood to produce
enough urine.
Causes of Dangerously Low Blood Pressure Include:
Blood loss: When a person is bleeding, there is a hole in the bloodstream and blood is leaking out. If a person
has lost a lot of blood, even if they are bleeding internally, the body is unable to compensate for this pressure
leak, and the blood pressure goes down.
Dehydration: If a person has not taken in enough fluids, they begin to lose too much fluid through their urine,
stool, breath, and skin. This can cause the blood pressure to drop.
Heart attack and heart failure: When part of the heart muscle dies after a heart attack, or when the heart is
fatigued from pumping under very high pressure, it begins to fail and cannot squeeze hard enough to generate the
pressure needed. This causes the blood pressure to drop.
Irregular heart rates: A heart which is beating very slowly fails to generate adequate pressure. Similarly, a
very fast beating heart or a heart beating with a very irregular rhythm is inefficient and unable to generate adequate
pressure. This can cause a low blood pressure.
Drugs, medicines: Many medicines decrease the blood pressure, and if overdoses of these medicines are taken,
they can decrease the blood pressure to dangerously low levels.
Measuring the blood pressure in both arms: Sometimes the blood pressure is measured in both arms in the same
way the pulse is sometimes taken in both arms. If there is a big difference between the two, this could mean that
there is a narrowing in one of the main arteries. Occasionally the blood pressure is measured in one arm and in one
leg. If the difference is large, this could mean that there is a narrowing in the body's largest artery, the
aorta.
A person's blood pressure may change from lying down to sitting up or standing. Your doctor will occasionally ask that
your blood pressure be taken in the lying, sitting, and standing positions. When you sit or stand up, more of your
blood collects in your arms and legs which causes a brief decrease in blood pressure. The brain usually senses this
and squeezes down on these vessels so that more blood returns to the heart, and the blood pressure goes back up to
normal. So normally, one's blood pressure should remain relatively stable when measured in these different positions.
In some illnesses and when a patient is dehydrated or has lost blood, her or his blood pressure might be normal when
laying down. However, once the patient sits up and gravity pulls blood into her or his legs, the blood pressure will
drop. Because the patient already has a decreased amount of blood in her or his vessels, the brain is unable to
compensate enough, the blood pressure remains low, and the heart rate goes up. When a person's blood pressure goes
down and stays down (or their heart rate goes up more than about 15 beats per minute when moved from lying to sitting),
this may mean that the patient's blood volume is low, and she or he may need either fluids or blood.
- Body Temperature:
It has long been said that the normal human body temperature is 98.6 degrees
Fahrenheit. However, recent studies have shown that a person's normal body temperature can be as high as 99.9 degrees
Fahrenheit. Body temperature normally fluctuates over a 24 hour cycle and is lowest at four in the morning and highest
at six o'clock in the evening. Body temperature is closely regulated by the brain. In cold conditions, the brain speeds
up the body's metabolism causing it to generate more heat. In warm conditions, the heat generated by the body's normal
metabolism is released by the body in special ways. For example, the skin begins to sweat and this causes cooling.
Also, more blood is sent to the skin where the heat can be released.
HOW TO TAKE THE TEMPERATURE:
To record the temperature, a thermometer (either mercury or electric) is placed in close contact with the body for
several minutes. The temperature is then read off the scale or meter. Body temperature can be measured in several
places: the mouth, under the arm, in the ear, and in the rectum.
The most accurate measurement of body temperature is the rectum since this is completely inside the body. A rectal
temperature of greater than 100.5 is generally said to be a fever. When the temperature is taken in the mouth, it is
generally 0.7 degrees lower than the rectal temperature. When it is taken under the arm, it is generally 1.0 degree
lower than the rectal temperature. Remember that normal body temperature is a range and not a specific number.
Causes of high temperatures (fevers): Vigorous exercise (like long distance running) can cause the body
temperature to increase two to three degrees Fahrenheit. In addition, many illnesses cause fever. These include
infections, tumors, connective tissue diseases (such as rheumatoid arthritis), and drugs. Because fever is such a
general sign and has many causes, it is a good indicator that something is wrong but does not accurately indicate what
is wrong. Most often fever is a sign of infection of some sort.
When the body has a higher than normal temperature (fever), it does not mean that the brain has stopped regulating
body temperature and that things are out of control. What has happened is that the body has reset its own thermostat
and is still regulating the temperature, but at a different level.
Some scientists think that by raising its temperature, the body is better able to fight off disease because germs have
a more difficult time growing at higher temperatures.
Another function of fever is obvious -- it makes you feel miserable so you go to bed and get some rest which could
help you recover.
Very high fevers, such as fevers greater than 104 degrees, can be dangerous. When the body temperature is elevated,
certain chemical reactions do not occur at their normal rate because the enzymes that control them are partially
inactivated at very high temperatures. This means that people with a fever have limitations in their body's normal
functions which explains why a fever causes a person to feel weak and achy. Children with high fevers, in addition to
being affected by decreased body function, are also at risk for having seizures, and so their bodies are often cooled
artificially with cool water to prevent seizures.
Causes of low body temperature:
A body temperature below 96 degrees is abnormally low. The most common cause of low body temperature is exposure to
cold weather. Here too, the body's enzymes do not function effectively and chemical reactions are slowed. This
condition responds well by warming with blankets and is usually not a very big problem.
- The Level of Oxygen in the Blood (Pulse Oximetry):
For many years there were only four vital signs, however, modern technology has developed a simple way of measuring
the oxygen content of the blood. This measurement is called pulse oximetry and is done by placing a light sensing
device on the finger of the patient. The light shines into the finger, detects each heart beat, and interprets how
much oxygen is being carried in the blood. This is especially useful in patients with asthma, emphysema, and pneumonia
who may have difficulty getting enough oxygen into their blood. Normally, the hemoglobin in the blood is 95-99%
saturated with oxygen. When the lungs are diseased or when breathing is inadequate, this level can drop to 60 or 70%.
It is important to know this so that adequate treatment can be given and so that it may be determined whether that
treatment is working. Pulse oximetry is so simple and accurate that it is being used more often and is being considered
by some as the new fifth vital sign.
