5 Vital Sign Errors to Avoid

Vital signs are essential in every aspect and setting of medicine – whether that be inpatient such as in the emergency department, the Intensive Care Unit (ICU), the medical/surgical floors, or pediatrics – as well as virtually every outpatient office setting.

Vital signs are objective measures of a patient’s health and can tell A LOT of information about the patient.

This can give great indications of their health status and prognosis, as well as aid in the differential of many different medical conditions.

When a patient can’t speak, sometimes all the medical team has to go on is their vital signs. Vital signs, matched with a thorough history and physical assessment, can mean the difference between life and death.

To sum it up – vital signs are SUPER important. While ignored by many, the slightest changes in vital signs can clue the nurses and Providers into acute changes in the patient’s status, and diligence with early correction can avoid prolonged hospitalizations and improve patient outcomes.

Vital signs are frequently obtained by nursing assistants, patient care technicians, medical assistants, nurses, and sometimes even physicians or advanced practice providers. All are important to the healthcare team. We ALL know how to take vital signs, but it is up to the Provider (often notified by the nurse) to interpret those vital signs and make patient interventions accordingly.

It is because of this crucial importance that it is absolutely necessary that vital signs are taken correctly to give the most accurate readings. There are many errors that novices and even some experts can make when taking vital signs, but these 5 errors will help any member of the medical team to provide accurate measurements.

1. Incorrect Cuff Size and Location

Blood pressure is a key vital sign to obtain, and it seems everyone is worried about their blood pressure. This is because high and low blood pressure are indications of underlying diseases.

A very high blood pressure could indicate uncontrolled hypertension, a stroke, a medication reaction, etc. Low blood pressure could indicate internal bleeding, systemic infection (sepsis), an adrenal crisis, etc. The lists go on. So many different diseases affecting various body systems can affect the blood pressure, and this is why it is so important to obtain the right measurement.

Blood pressure cuffs should be sized appropriately to fit the patient’s arm. But what is appropriate?

The correct answer is that the bladder (the part that inflates with air) should encompass 80% of the person’s arm circumference. That means it should just about fall short of wrapping around their entire arm.

In reality, though, you just kind of know if it’s too big or too small after some experience. Most adults with regular-sized arms will fit the regular adult size, and larger individuals or gym-rats will benefit from the larger size. It should fit nice and snug, but not too snug.

Place the middle of the bladder (usually marked with some type of marking such as “Artery Here”) over their brachial artery. This is usually on the medial aspect of their antecubital fossa. Place the cuff 2-3cm above the crease, or about an inch.

So why does it matter so much? Incorrect cuff sizes will lead to incorrect blood pressure measurements. If you place a cuff too small on an individual, the blood pressure will likely be falsely elevated. If you place a cuff to big on an individual – you guessed it – the reading could be falsely decreased.

This becomes very important when blood pressures begin to push the boundaries of normal.

2. Incorrect Positioning

Patient positioning, which is also important in blood pressure, should not be overlooked.

In the office-setting, patients should be seated with uncrossed legs for 5 minutes before getting their blood pressure checked. This usually does not lead to many issues due to the routine and setting of the office.

However, in the hospital, this error occurs very frequently. While patients do not need to be sitting in a chair for 5 minutes prior to a blood pressure reading within the hospital, it is important to maintain proper positioning.

Patients are often going to be bed-bound, on bedrest, or perhaps sleeping when you go to take their vital signs.

Placing the patient in Semi or high fowler’s positioning for at least 5 minutes before checking the blood pressure is ideal, but supine is often accepted as well.

The MOST IMPORTANT thing to remember is that the blood pressure cuff is at the level of the heart (more specifically the right atrium) when the reading is taken.

Patients who are on their sides will give you inaccurate readings. The arm above their heart will read falsely lowered readings, and the arm below may render falsely elevated readings.

This is common, especially within the units that have constant blood pressure monitoring with frequent intervals (ER and ICUs).

3. Incorrect Waveform

Blood oxygen saturation is monitored with a pulse-oximetry sensor usually on a finger, and this is another important vital sign which we need correct measurements.

While of great value, sometimes oxygen sensors read incorrectly low, and with a little practice, it can be easy to learn when a low reading is actually dangerous vs when it is just artifact.

The important thing to check with a pulse-ox reading is whether or not there is a good wave-form.

This is usually within the hospital where a bedside monitor or dynamap displays the “pleth” – that is, the waveform that “beats” in congruence with the heartbeat.

Peripheral pulse ox’s can measure how much blood is passing with each beat through the device sensor. This should look equal, symmetric, and have adequate amplitude.

If all you see is a straight line with occasional movements, this is NOT a good pleth, and likely an inaccurate reading.

The waveform or pleth may look poor due to poor circulation (cold fingers, peripheral artery disease, hypotension, etc), or the patient may be shaking or moving their finger too much.

Try changing to a different finger or hand. With cold fingers with poor circulation, try using an earlobe (infant probes are often easy to use in this location).

If the patient has nail polish on, you may be able to get a reading but it is possible that this is interfering with the spectrum of light for the sensor. If you are getting a bad reading – it may be wise to remove the nail polish on one finger and try again.

Another important fact to remember is to ALWAYS CHECK THE HEART RATE from the pulse-ox. Does this match their HR on the heart monitor? If they are not hooked up to the heart monitor, does this match their peripheral pulse? If your heart monitor reads a HR of 82, and your Pulse-ox is reading 78% and a HR of 30 – this is likely not a good reading as the heart rates do not match up. The exception is an arrhythmia, so make sure they are in a Sinus Rhythm before assuming it is an error.

4. Incorrect Temperature Method

Infections often present with fevers, and severe infections can have either really high temperatures or really low temperatures.

It is important to use the correct temperature method for the correct situation, as using the wrong method can lead you to not picking up on a fever.

Oral Method

In most settings and for most patients, the oral thermometer is adequate. As long as the patient can follow instructions and leave it under their tongue for 10 seconds or so, you will likely get an accurate reading.

However, if the patient recently drank something, this can lead to a falsely lower reading. The colder and more recently they drank it, the more likely it is to interfere with the reading.

Cold beverages can decrease the temperature for up to 30 minutes, and hot beverages can falsely elevate the temperature for up to 5 minutes or so. Interestingly enough, if the patient is chewing gum this can also slightly increase the temperature reading.

Additionally, if the patient has a high respiration rate (greater than 20 breaths per minute), this can lead to falsely low readings. In these instances, it may be prudent to check the temperature with another method.

Rectal Method

The rectal thermometer is the “gold standard” because it is the closest to the core body temperature, but it is not always practical.

Studies have shown that a significant amount of fevers are missed in triage due to less invasive methods. Rectal temperatures should be obtained on anyone with whom there is suspicion of fever when other methods are afebrile.

A basic summary is that a rectal temperature should be performed on those suspected of serious infection or sepsis, those with hypothermia from the field, and those who are critical or unresponsive.

Rectal temperatures are also frequently obtained in children under a certain age. It depends on facility protocol, but obtaining rectal temperatures in infants and young children (often under 2 years) is common, especially if they present with complaints of fever.

Rectal temperatures tend to be 0.5-1.0°F HIGHER than the “normal” oral temperatures – 98.6°F.

Temporal Method

The temporal method is dependent on the facility and available equipment but does offer quick and fairly accurate temperature readings.

If the patient is not very acute, has no symptoms, and simply needs a quick screening temp – the temporal thermometer can be your best friend.

However, the diagnostic accuracy of the temporal thermometer is iffy, and if there is concern for altered temperature, another method should likely be used.

Forehead sweat is a common cause for false low readings. 

Tympanic Method

The tympanic method is commonly used in and out of the hospital setting but often can yield lower-than-accurate readings.

This is often due to the fact that the end of the probe needs to be pointed directly at the tympanic membrane. Improper technique can lead to inaccurately low readings.

If done properly, tympanic readings actually tend to run hotter than oral readings, similar to rectal readings at 0.5-1.0°F higher than 98.6°F.

The tympanic thermometer has shown to be useful, comfortable, and generally tolerable. It is generally appropriate to use 6 months and older, depending on the device.

Axillary Method

Axillary temperatures tend to be unreliable and are not often recommended in the hospital setting.

They can be used for screening purposes in the office-setting if the patient is not complaining of fever. Additionally, they can be used for screening in an infant or young child, but some settings will accept an axillary temperature for children above 2 years old.

This method often yields results about 0.5-1°F lower than 98.6°F. If there is any doubt, use another method.

These readings will be inaccurate in very sick patients who have compensatory peripheral constriction or dilation, so this method should generally be avoided within the hospital.

Long story short – do a rectal when the patient is severely sick or unresponsive, in those very young (generally under 2), and in various specific circumstances when asked or ordered by the provider.

In all other scenarios, use the most appropriate, comfortable, least-invasive method which is likely to yield accurate results.

5. Respiration Rate

The respiration rate is crucial in evaluating those with respiratory complaints.

It can clue the clinician into impending respiratory failure, indicate acid-base balance, and guide patient interventions. However, it seems as though most hospital workers (nurses, techs) don’t actually count respirations.

It happens very often when someone just puts “16”, “18”, or “20” – without even thinking twice. I can’t even tell you how many times another medical professional put in a normal respiration rate and the patient actually had a rate greater than 30, sometimes above even 50.

I get it – do you REALLY want me to stand here and count their respirations for 30-60 seconds?! AINT NOBODY GOT TIME FOR THAT, and we are BUSY. However, accurate respirations can lead to quick and timely recognition of a change in patient status.

All in all, you should be counting. But if the patient appears to be breathing fast, having respiratory difficulty, is an infant, or came in with a respiratory complaint – this becomes a necessity and there really is no excuse for “just putting 16”.

Hopefully you found these errors illuminating and helpful. Remember to always try to obtain accurate results in the least-invasive, most respectful manner possible.

When in doubt, consult with the nurse, physician, or advanced practice provider.Let me know in the comments if you’ve seen these errors occur, and any other errors that might be helpful to other readers!