How to do a 12-Lead ECG?

How to do a 12-Lead ECG?

Since the American Heart Association’s recommendation to obtain prehospital 12-lead electrocardiograms on patients with acute coronary syndrome, EMS providers have played an increasingly important role in identifying these patients, beginning the appropriate treatment, and transporting them to appropriate hospitals capable of emergency angioplasty.

The acquisition of the 12-lead ECG in the field is theoretically not different from those obtained inside the emergency department. However, due to the unique prehospital environment, there are several tips and pearls to consider when placing the patient electrodes.

Conditions Requiring an ECG

A 12-lead isn’t just for chest pain. Obtain a 12-lead for possible strokes, altered levels of consciousness, weakness, dizziness, fatigue, palpitations and otherwise vague medical complaints. Remember that diabetic patient, younger women and various ethnicities often have atypical presentations and may have “silent myocardial infarctions.” Be vigilant. You may just save a life.

Proper acquisition of the 12-lead ECG

Proper acquisition of the 12-lead ECG is paramount to getting the most out of this tool. An improperly acquired 12-lead doesn’t provide diagnostic-quality information and can render the tracing mostly useless. Here are a few tips to making sure you get it done right:

Skin Preparation

Skin Preparation

It’s important to prepare the skin by cleaning it with an alcohol prep and by abrading it with a cloth towel to remove dead skin cells. You may need to wash the area with saline and dry it. Remove excess body hair by shaving. For females, place the leads under the breast tissue. You may need to lift and clean the skin underneath the breast to get a clear tracing.

Lead Placement

12-lead ECG placement

Traditionally, the limb leads go on the limbs, and while it’s acceptable to move them closer if you have to, try to avoid placing the leads over bony prominences or overly fatty areas. Look for a generally flat, clean, intact area of skin with muscle generally underneath.

  • The V-Leads go on the chest in a specific pattern. Leads V1 and V2 go in the 4th intercostal spaces (between the ribs) on either side of the sternum. To find these, go about three finger widths up from the xyphoid process, or bottom of the sternum. V1 is on the patient’s right, V2 is on the left.
  • V4 should be placed next; it goes one rib down in the 5th intercostal space, on the midclavicular line. Place V3 in between V2 and V4.
  • V5 goes in the anterior axillary line (front of the armpit) and V6 goes in the mid-axillary line. They go in the same horizontal line as V4.

Electrode Placement for Women

Electrode Placement for Women

Asking a female patient to disrobe can be uncomfortable for the EMS provider, at first. Be professional. Explain to the patient what you plan to do in terms of electrode placement; emphasize that several of the chest leads may need to be placed around and under the left breast.

Have a patient gown available for the patient to use after removing her clothing.

If the patient’s left breast is large enough to cover the V3, V4, or V5 placement area, it will have to be lifted up for proper electrode placement. If possible, you can ask the patient to lift her own breast. Alternatively, use the back of your straightened hand to displace the breast.

Electrode Placement for Bariatric Patients

Electrode Placement for Bariatric Patients

Obese patients may appear to be more difficult at first to accurately place electrodes. The trick is to spend a few extra moments locating the anatomic landmarks. Palpate more deeply to feel the sternal border and Angle of Louie to place leads V1 and V2. V4 is usually located in a straight line below the nipple at the fifth intercostal space. Then, imagine a line track straight down the left lateral side of the chest. Along this line, at the mid-axillary line is the location of lead V6.

Once these leads are placed, then V3 is placed halfway between V2 and V4. Finally, V5 is placed halfway between V4 and V6.

Electrode Placement for Pregnant Patients

Electrode Placement for Pregnant Patients

Despite the appearance of the abdomen during advanced pregnancy, the placement of the electrodes is the same. You can use the technique above if necessary.

Note that left-axis deviation on the ECG may appear in both pregnant and obese patients. This is due to the abnormal position of the heart as the diaphragm pushes high into the thoracic cavity.

Electrode Placement for Pediatric Patients

lectrode Placement for Pediatric Patients

Use smaller electrodes specific to children. Adult electrodes will overlap and potentially cause inaccurate placement. For preschool-age children and older, take time to explain what you are doing. Young children will be fearful of the procedure and may imagine that it will hurt, or that you will shock them. Having a parent close by will help provide reassurance.

Obtaining 12-Lead ECG in Extreme Environments

Extreme heat or cold will affect the integrity of the electrode’s conducting gel. During the cold winter or hot summer months, check to make sure that the electrode bag is kept in a location that minimizes dramatic temperature shifts.

Acquisition Tips to Minimize Artifact

Movement of any sort has the potential to create excessive artifacts in the ECG. Consider these tips:

If your patient is shivering, cover the skin with a light sheet and consider using a small heat pack to provide a sense of comfort. Turn the thermostat in the ambulance up to keep the patient warm.

The patient should be in a semifowler’s position.

Ask the patient to simply breathe normally and keep their hands by their sides. This prevents them from gripping the handrails too tightly, which can cause minute muscle tremors that show up on the ECG as artifacts.

There should be some “slack” in the patient cables. If the cable is taut between the electrode and the monitor, adjust the cable to release the tension.

With practice and preparation, obtaining a clean 12-lead ECG every time will be easier to accomplish. Your confidence in acquiring an accurate tracing will decrease the time it takes to decide how to manage and transport the patient who is experiencing ACS, and increase the chance of survival and recovery.


A quality 12-lead ECG has a smooth, flat baseline (called the isoelectric line). Baseline wander, or the vertical motion of the ECG line, can mask important findings in the ECG tracing and result in a non-diagnostic ECG.

The patient should remain motionless and lay as close to supine as possible for the acquisition of the tracing and the ambulance should be stopped and not move during the process. It sometimes takes a few minutes for the ECG tracing to normalize and you should wait for it to do so. The goal is to be able to see the entire cardiac waveform clearly and be able to measure accurate ST-segment levels. Skin prep is important to reduce artifacts. A tracing with artifact or baseline wander can mask serious ECG findings and may cause a patient to be misdiagnosed.

A-Fib Risk Factors

A-Fib Risk Factors

Atrial Fibrillation (A-Fib)

Arial fibrillation is an irregular heart rhythm that can lead to inadequate blood supply and blood clots in the heart.
normal heartbeat vs atrial fibrillation ecg

Arial fibrillation Symptoms

Common Signs:

  • Panic
  • Palpitations
  • Chest tightness
  • Shortness of breath
  • Dizziness, or even blackness and fainting in severe cases
  • Weakness

Severe Signs:

  • A drop in blood pressure
  • Dyspnea
  • Some patients can have no obvious conscious symptoms when atrial fibrillation attacks.

What are the risk factors for developing atrial fibrillation?

Afib risk factors
  1. Age

The risk of atrial fibrillation increases with age, up to 5% in people over 65 years old and up to 10% in people over 75 years old.

  1. Obesity, Overweight

The risk of developing atrial fibrillation was 1.22 times higher in overweighted people and 1.65 times higher in obese people than in normal-weight people.

  1. Sleep apnea

We tend to think of people who snore as sound sleepers, but in fact, a significant number of people who snore have A-Fib. Patients with sleep apnea have poor sleep quality, frequent awakenings at night and lethargy during the day. Severe cases require a homeused ventilator or pharyngeal surgery.

O2Ring, a ring, is recommended to monitor your blood oxygen levels, so as to diagnose the condition of sleep apnea. Many users approved its effect. Click here to read its reviews.

  1. Hypertension

Hypertension is one of the most important causes of atrial fibrillation. Among many risk factors of cardiovascular disease, hypertension is the most dangerous one. How to prevent hypertension:

  1. Keep fit.
  2. Limit salt intake.
  3. Cut back on fast food.
  4. Limit alcohol.
  5. Stop smoking.

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Wi-Fi blood pressure monitor with ECG function help you to measure continuous blood pressure and track 30s ECG. With the help of the AI-ECG platform, people who don’t have the professional knowledge can also know the ECG interpretation since this platform has been approved to detect some special ECG events.

  1. Diabetes

Both type 2 and type 1 diabetes can increase the risk of atrial fibrillation.

5 Ways to Prevent Diabetes and Atrial fibrillation:

  1. Increase physical exercise.
  2. Eat foods rich in fiber.
  3. Try to choose whole grains.
  4. Lose weight.
  5. Instead of dieting on a whim, stick to a healthy, balanced diet for the long run.
  1. Smoking

Smoking significantly increases the risk of atrial fibrillation, with current smokers having twice the risk of atrial fibrillation as nonsmokers. Quitting smoking can lower the risk of atrial fibrillation.

  1. Drinking

Don’t drink too much wine, though it adds to the fun. If you don’t have a drinking habit, don’t raise your glass for the so-called “blood vessel softening” effect. Because the glass of alcohol may be a small cardiovascular assistant, but more likely to be a gentle “killer”.

  1. Some drugs

Adenosine, dobutamine, evabradine, non-steroidal anti-inflammatory drugs (such as celecoxib, ibuprofen), high doses of hormones, aminophylline, and bisphosphonates (such as alendronate) can increase the risk of atrial fibrillation. However, in most cases there is no need to discontinue medication because of these risks, adding or removing medications should be done under the guidance of a physician.

  1. Anger, anxiety and other emotions

Not only can a bad mood increase the risk of atrial fibrillation in healthy people, but it can also make it more frequent in those who already have it. It is even associated with recurrence after catheter ablation of atrial fibrillation. If you have depression and anxiety that cannot be relieved for a long time or find yourself unable to control anger, please go to a professional clinic in time.

  1. Lack of endurance training

Physical inactivity is a contributing factor to many cardiovascular diseases, but more physical activity is not always better, and high-intensity endurance training may increase the risk of atrial fibrillation. Moderate intensity training benefits the most.

  1. Hyperthyroidism

The proportion of patients with hyperthyroidism complicated with atrial fibrillation is quite surprising. The primary task for the treatment of atrial fibrillation is to control hyperthyroidism. After treatment, more than half of patients can restore normal sinus rhythm by themselves.

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How Important is 12-Lead ECG Machine in Emergency Medical Service?

How Important is 12-Lead ECG Machine in Emergency Medical Service?

Emergency medical service(EMS) is an essential part of the health care system and is always expected to be available always and continuously in case of need.

The 12-lead ECG is one of the most fantastic advances in EMS treatment since the invention of the bandage. It has proven to be a landmark addition to the EMS toolkit as the critical diagnostic aid to provide care in the field, guide transport to the most appropriate hospital for acute heart conditions, and allow notification of the hospital so that emergency staff can be prepared.

The movement of this powerful diagnostic tool from the confines of the hospital to the streets has been nothing short of revolutionary. It has given EMS professionals a wealth of information on how to best care for our patients and has driven hospital care and the development of medical care practices by providing clear and critical data that physicians had rarely before seen.

What is a 12-Lead ECG Machine?

A 12-lead electrocardiogram (ECG) is a medical test that is recorded using leads, or nodes, attached to the body.

It can identify a variety of heart problems, rhythm abnormalities, and cardiac injuries. Its addition serves as the basis for updating EMS protocols to improve the care of patients suffering many types of acute cardiac events.

Most importantly, the 12-lead EKG is the only tool to identify a patient with an ST-elevation myocardial infarction (STEMI).  It could reproduce QRS, ST, and T waveforms accurately, and provides evidence of P wave and QRS complex morphology that cannot be determined by single-Lead ECG. 

Not all hospitals provide acute treatment interventions for this condition, so the crucial EMS role is to identify patients with that disease and then, if possible, transport the patient for immediate intervention. There are many outstanding cases of EMS personnel identifying the patient having an MI, communicating that condition to the emergency department, and helping move the patient to the cardiac lab.

Application of 12-lead ECG in the diagnosis of STEMI

For ST-elevation myocardial infarction, the mortality of patients is closely related to the time from chest pain to perfusion (Ischemic to balloon time, also called myocardial hypoxia time).

The demonstrated advantages of 12-Lead ECG in EMS

Help doctors diagnose early, perform automatic interpretation or transmit ECG to expert

In 2006, the New England Journal of Medicine published that if the cardiac catheterization room can be activated before the patient arrives at the hospital, it will effectively reduce the time of myocardial hypoxia. However, the proportion of patients who can complete the pre-hospital ECG diagnosis is still not high.

In some cities, ambulances are equipped with 12-lead ECG equipment. When the fire rescue arrives at the rescue scene, they can first perform an ECG examination according to the condition. If it is judged to be STEMI, then the catheter would be called to activate immediately. In this way, when the patient arrives at the hospital, the Cath Lab would be ready to arrange cardiac catheterization, so as to reduce the preparation time of the cath lab, thereby shortening the time from hospital to perfusion.

Actually, even if the ambulance directly transfers the patient to the cardiac catheterization hospital, the activation of the cath lab will take a lot of time, which includes the organization of the cardiac catheterization team, the preparation of machines and equipment, etc. At present, if the hospital needs to activate the acute cardiac catheterization team, the notification can only be confirmed after the patient arrives at the emergency room and complete the ECG diagnosis.

In the emergency scene, 12-Lead ECG is used to complete the ECG detection, and some of the machines are able to automatically interpret and transmit the ECG report to the expert to establish the diagnosis result in advance, and then transfer it to the cardiac catheterization hospital, thus the early treatment could reduce the time of myocardial hypoxia and mortality rate effectively.

How Wellue can help

Wellue offers two types of portable 12-Lead ECG Machines, the Biocare 12-Lead EKG Machine, and the Wellue® 12-Lead ECG Tablet. By popularizing these tools into the field, they have almost made heart attacks into minor medical complaints that can be effectively treated if caught early.

Wellue® 12-Lead ECG Tablet

Wellue 12-Lead ECG Tablet

The flexible size of 197mm×112.4mm×26.1mm (7.8”x4.4”x1.0”), makes it easy to fit in your pocket. With the Wellue® 12-lead ECG tablet, you can make heart diagnoses everywhere immediately on your hand. 

There are two measuring methods to choose from 9 leads and 12 leads. Whether in an ambulance, fire rescue or field medical, air rescue, no need to print, editing EKG reports, analyzing, reviewing, and saving data will all take place in one touch-screen tablet. Most importantly, this tablet supports file sharing between Android devices, therefore the EMS team can send reports to the hospital on their way. Once a physician confirms the result, the hospital can take the patient with a severe heart attack to the cath lab directly. Wellue® 12-Lead ECG tablet helps to make faster cardiac medical decisions and will largely improve the efficiency of heart diagnosis.

Biocare 12-Lead EKG Machine

12-Lead EKG Machine

This portable EKG machine only weighs 1.3kg (2.9lbs). Compares to many EKG devices which normally weigh about 2kg (4.4lbs), this EKG machine is definitely an indispensable tool in the EMS toolkit.

The set includes a metal handle for emergency staff to carry around in the rescue.

This compact machine is also equipped with a printer,  which prints out the analysis in 3×4 format. So you can get a quick view of your patients in just a few seconds, and pass the result to cardiologists or physicians so that the hospital can get ready in advance.

What Is the Normal Blood Oxygen Level? Is My Blood Oxygen Level Normal?

What Is the Normal Blood Oxygen Level? Is My Blood Oxygen Level Normal?

What your blood oxygen level shows

Your red blood cells are like vehicles. Each can carry up to four oxygen molecules across your body, getting them to places like your heart and brain. Your body’s vital systems need a normal percentage of oxygen inside your blood at all times, known as your oxygen saturation. However, sometimes your blood can get either too much or too little oxygen, and in these cases, there can be serious health consequences.

People with chronic health conditions many need to monitor their blood oxygen level. This includes asthma, heart disease, and chronic obstructive pulmonary disease (COPD).

In these cases, monitoring your blood oxygen level can help determine if treatments are working, or if they should be adjusted.

Keep reading to learn where your blood oxygen level should be, what symptoms you may experience if your level is off, and what happens next.

messuring blood oxygen level with Wellue O2ring

Where your blood oxygen level should fall

A measurement of your blood oxygen is called your oxygen saturation level. In medical shorthand, you may hear it called a PaO2 when using a blood gas and an O2 sat (SpO2) when using a pulse ox. These guidelines will help you understand what your result might mean:

Normal Blood Oxygen Levels

Older adults typically have lower oxygen saturation levels than younger adults. For example, someone older than 70 years of age may have an oxygen saturation level of about 95%, which is an acceptable level.

It is important to note that the oxygen saturation level varies considerably based on a person’s state of health. Thus, it is important to understand both baseline readings and underlying physiology associated with certain conditions to interpret oxygen saturation levels and changes in these levels.

  • People who are obese and/or have conditions such as lung and cardiovascular diseases, emphysema, chronic obstructive pulmonary disease, congenital heart disease and sleep apnea tend to have lower oxygen saturation levels.
  • Smoking can influence the accuracy of pulse oximetry in which the the SpO2 is low or falsely high depending on whether hypercapnia is present. With hypercapnia, it is difficult for the pulse oximeter to differentiate oxygen in the blood from carbon monoxide (caused by smoking).
  • Oxygen saturation levels may decrease slightly when a person is talking.
  • Oxygen saturation may remain normal (e.g., 97% and higher) for people with anemia. However, this may not indicate adequate oxygenation because there are less hemoglobin to carry an adequate supply of oxygen for people who have anemia. The inadequate supply of oxygen may be more prominent during activity for people with anemia.
  • Falsely low oxygen saturation levels may be associated with hypothermia, decreased peripheral perfusion, and cold extremities. In these cases, an ear lobe pulse oximeter device or arterial blood gases would provide a more accurate oxygen saturation level. However, arterial blood gases are usually only taken in critical care or emergency settings.

Points to Consider

For medical purposes, a normal blood oxygen saturation rate is often considered between 95% and 100%.In practice, the SpO2 range of 92–100% is generally acceptable for most clients. Some experts have suggested that a SpO2 level of at least 90% will prevent hypoxic tissue injury and ensure client safety (Beasley, et al., 2016).

Low Blood Oxygen Levels

The medical definition of a low blood oxygen rate is any percentage below 90% oxygen saturation. Oxygen saturation below 90% is very concerning and indicates an emergency. Call 911 immediately if you or someone you know experiences such a low blood oxygen level.

When Low Oxygen Saturation Affects Your Brain

By the time your oxygen saturation has fallen to between 80% and 85%, your brain may be affected by the lack of oxygen. You may also experience vision changes.

What happens if your oxygen level is too low

When your blood oxygen level goes outside the typical range, you may begin experiencing symptoms.

This includes:

shortness of breath

chest pain



rapid heartbeat


The first visible symptoms of low blood oxygen, cyanosis causes a blue tinge to develop on your skin, particularly around your mouth and lips and beneath your fingernail matrix. This change occurs when your blood oxygen saturation reaches approximately 67%.

Cyanosis is considered an emergency. If you’re experiencing symptoms, you should seek immediate medical attention. Cyanosis can lead to respiratory failure, which can be life-threatening.

What causes blood oxygen levels to be low

Conditions that can negatively affect your blood oxygen level include:

COPD, including chronic bronchitis and emphysema

acute respiratory distress syndrome


collapsed lung


congenital heart defects

heart disease

pulmonary embolism

These conditions may prevent your lungs from adequately inhaling oxygen-containing air and exhaling carbon dioxide. Likewise, blood disorders and problems with your circulatory system may prevent your blood from picking up oxygen and transporting it throughout your body.

Any of these problems or disorders can lead to declining oxygen saturation levels. As your oxygen levels fall, you may begin experiencing symptoms of hypoxemia.

People who smoke may have an inaccurately high pulse ox reading. Smoking causes carbon monoxide to build up in your blood. A pulse ox can’t tell the difference between this other type of gas and oxygen.

If you smoke and need to know your blood oxygen level, an ABG may be the only way to receive an accurate reading.

How to adjust your blood oxygen level

If your blood oxygen level is too low, you may need to boost your oxygen saturation. This is often done with supplemental oxygen.

Home supplemental oxygen is considered a medication, and your doctor must prescribe it. It’s important to follow your doctor’s specific advice on how home oxygen should be used to avoid complications. Your health insurance may cover the expense.

Self-care Diet of Patients with OSA

Self-care Diet of Patients with OSA

What do patients with OSA need to pay attention to in their daily diet?

What you eat for dinner can have a big impact on how you fall asleep. Some foods have been approved to promote healthy sleep, while those with anti-inflammatory ingredients can help keep airways open during sleep. Foods that are good for weight loss are also good for sleep! A “health-conscious” diet of fruits, vegetables, whole grains, and lean proteins can be helpful for sleep apnea treatment.

Foods that can disrupt sleep include heavy meals with lots of sugar and carbohydrates. If you eat a big meal before bedtime, your body will take longer to relax and sleep.

foods to avoid before bedtime if you have OSA

If you have obstructive sleep apnea (OSA), foods to avoid before bedtime include:

You should avoid foods that can cause acid reflux and heartburn, which are common causes of sleep apnea. It’s best not to eat anything two hours before going to bed. Avoiding these foods at night may also benefit you if you have a diagnosis of sleep apnea:

  • Bananas – Soft, overripe bananas increase mucus production and make your breathing worse when you sleep.
  • Spicy foods – These can cause heartburn and may stimulate your throat. Spicy foods can also increase your body temperature while you sleep.
  • High-fat dairy products and meat – These foods are digested very slowly and may cause cramping or bloating if you eat a lot of them and lie down immediately. Controlling your fat intake can complement your sleep apnea treatment and reduce your weight.
  • Alcohol – Drinking alcohol may help you fall asleep, but it may prevent you from entering the high-quality REM (rapid eye movement) sleep phase. It can also relax your throat and may increase your risk of upperway airway obstruction.
  • Caffeine – A stimulant known to keep you awake. You should avoid caffeine within six hours of bedtime.
  • Refined carbohydrates – Adding sugar to refined carbohydrates is a significant factor in weight gain and increased risk of sleep apnea.
  • Fiber-rich foods – It’s best to consume your daily fiber requirement at lunch time. Fiber-rich foods like broccoli and cabbage take time to digest and can leave you bloated in bed.

Eating the right food before bedtime can help promote healthy sleep and reduce sleep apnea symptoms. Some healthy, sleep-promoting bedtime snacks rich in melatonin and tryptophan are pistachios, mixed nuts, warm milk, cherry juice, fruit, honey and yogurt. However, keep in mind that everyone reacts to food in very different ways. Therefore, it is advisable to consult your healthcare professional about your sleep apnea treatment.

How do you know if you have sleep apnea? How to know the effect of the apnea treatment?

The simplest way is to monitor your blood oxygen levels overnight.

Oxygen saturation over 95% is normal. Oxygen levels below 92% and breathing stops accompanied by a drop in blood oxygen levels are signs that your have breathing problems during  sleep (sleep apnea, severe snoring, COPD, asthma, etc). So it’s important to know how much time you spend with oxygen saturation that goes below 92%.

O2Ring continuous oxygen monitor is an useful device for sleep apnea patients.

  • Much cheaper than a sleep study, this ring-shaped pulse oximeter can monitor your blood oxygen levels for up  to 12 hours.
  • Syncing the data to your phone app, you will get a sleep report to tell you how much time that your oxygen levels are below 95% and how many times that your oxygen levels drop.
  • For sleep safety, this device also can vibrtae silently if your abnormal readings are detected, which can alarm you to prevent from stop breathing.
wearing o2ring pulse oximeter
o2ring oxygen monitor
o2ring app sleep report

Sleep Apnea Treatment — CPAP Machine

OSAS was diagnosed when breathing stop was 5 times per hour. and non-invasive ventilation was judged to be necessary when breathing stop was more than 20 times per hour. Continuous positive airway pressure (CPAP) is the most commonly used to treat obstructive sleep apnea.

iBreeze APAP Machine is an ideal solution to treat OSA, helping you breathe freely and smoothly during sleep, and get the healthy life back again!

APAP machine
APAP machine 1