Reading a Patient Monitor.

Understanding the information displayed on a patient monitor.


We see them all the time in medical TV shows and movies, or if you’ve ever been unfortunate enough to land yourself in the emergency department of a hospital, you’ve likely seen the patient monitor screen, or the machine that’s always beeping about something! But what do all the sounds and squiggly lines mean? In this article, we’ll look at each of the body’s vital signs and how they’re interpreted through the patient monitor.

First, it is important to understand that vitals signs form a cohesive picture of the vital functions of the body, and should never be interpreted independent of each other. Some patient monitors are capable of tracking a wide array of parameters, but all will be able to track at least 4 of the 5 key vitals signs; heart or pulse (HR/PR), Oxygen Saturation (SpO2), blood pressure (BP) and temperature (T).

So the screen you are probably familiar with looks something like this:

Patient Monitor Screen
This screen gives a general overview of the patients vital signs. From this snapshot, most healthcare professions can tell you that the patient is very healthy, with no heart or lung problems, with good blood perfusion and a regular breathing patern. In-fact, this demonstrates the “perfect” vitals signs we would expect to see in a perfectly healthy individual, but of course, this is rarely the case. But lets jump ino the nitty gritty and get to know what all these colors and numbers mean.

The Layout;
There two primary areas on the display; the waveform area on the left, which displays a historical reading of the measurements over time, and the realtime number readout on the right.

The Numerical Readout

Patient MonitorThis is the first place we should look for all the patients vital statistics. It shos a realtime snapshot of all of the vital function of the body.

We can determine which measurement is being displayed by the letters in the top left of the display window;

PR Pulse Rate or Heart Rate (HR). This is a measure of how many beats the heart is performing per minute.
TEMP This is a measure of the body’s core temperature.
SpO2 This is a reading of how much oxygen in currently in the blood at the sensor site.
RR Respiration Rate. This is a measure of how many breaths are taken per minute.
SYST Systolic blood pressure. This is a measure of how much pressure is exerted on the artery walls during a heartbeat.
DIAS Diastolic blood pressure. This is a measure of how much pressure is exerted on the artery walls when the heart is at rest.
The SYST and DIAS measurements make up the two components of a Blood Pressure measurement, with SYST always on top of the DIAS reading. In this case, the blood pressure is 120/80, or 120 “over” 80.

The ECG Readout

ECG Readout
The first section we will look at in detail is the ECG readout. This shows a real-time and historical picture of the electrical activity of the heart, and how well it is functioning. Careful analysis of this waveform can give a health care professional an insight into how the heart is pumping, how efficiently it is working, and if there are any problems with the electrical circuit, known as the Cardiac Conduction System.

On most patient monitors, the ECG is represented with a green line. In this example, the two windows are an extension for displaying the historical readout of the waveform.

ECG’s are very complex in themselves, so we won’t go into any more detail here.

THE SpO2 Waveform.

Oxygenation Waveform
The next section is the SpO2 waveform, or the oxygenation waveform. This is a measure of the amount of oxygenated blood reaching the ends of the limbs, known as peripheral perfusion. This gives the health care professional an insight into how well the heart is pumping blood to the smaller capillaries of the body, as well as the amount of oxygen in the blood. If you look closely, each peak on the SpO2 waveform should correspond to a heartbeat on the ECG waveform, and that is indeed the case here.

On most patient monitors, the SpO2 waveform is usually denoted by a blue line.

The Respiration Waveform

Respiration Waveform
The respiration waveform is not common in standard patient monitors, but is quite common in the critical care areas. The wave simply measures the breaths the patient is taking, and can be used to identify apnea (sudden cessation of breathing) or dyspnea (difficulty breathing).

Many patient monitors will display the respiration wave as a yellow or white line.

So that’s it! Now you know what each of those crazy colored things on the screen mean. It is important to note that you should never try to interpret the values yourself, leave that to the professionals. There is an almost infinite amount of variables that can influence the readings, and these will be taken into account by any healthcare professional in order to determine if there is a problem or not. On the same note, just because the alarm is going off, does not neccesarily mean there is a problem.



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