First Aiders and anticipated AED users often hear manual defibrillators mentioned in the course of their training, but what is a manual defibrillator and how is it different from an automated external defibrillator (AED)? If you have an AED on-site or are curious about medical devices in general, understanding what a manual defibrillator is and how it works will help you provide the best possible response to victims of sudden cardiac arrest.
How a Manual Defibrillator Works
A manual defibrillator serves the same purpose as an automated external defibrillator: to save the life of a victim of sudden cardiac arrest. Sudden cardiac arrest takes place when there is an electrical malfunction in the heart, which causes the heart to stop beating. If a normal heartbeat is not restored within minutes, the victim’s brain cells and vital organs begin to die and their heart ultimately stops working altogether.
When applied in the 3 to 10 minutes following cardiac arrest (in conjunction with immediate chest compressions), an automated or manual defibrillator can provide electrical shocks to the heart that shut down the dysfunctional rhythms, allowing the heart’s own pacemakers to start up again—ideally with a normal rhythm. A shock can be effective in cases where there is ventricular fibrillation or pulseless ventricular tachycardia. It is not effective in cases of asystole or pulseless electrical activity (PEA).
Differences Between Manual and Automatic Defibrillators
Whereas an automated external defibrillator analyzes the patient’s heart rhythm and calculates the power of the shock automatically, a manual defibrillator allows the operator to determine the power of the shock (in joules) using the settings on the machine.
Because the energy level is set by the user, and because it doesn’t have the same safeguards that an AED offers (like warning the user when a shock is not advised), using a manual defibrillator requires high-level training in advanced cardiac life support.
Manual defibrillators generally come with three modes:
- Synchronized cardioversion
- External defibrillation
- Internal defibrillation
Additional Capabilities of Manual Defibrillators
In addition to offering greater control and customization, manual defibrillators have capabilities that automated external defibrillators do not. When connected to other medical devices, they can be used to monitor oxygen levels in the blood (SpO2), the concentration of carbon dioxide in each exhale (ETCO2), and blood pressure (NIBP). However, where manual defibrillators really shine is in their ability to perform non-invasive transcutaneous pacing and cardioversion.
Non-Invasive Transcutaneous Pacing (NTP)
Pacing, or non-invasive transcutaneous pacing, is the ability to provide pulses of current to stimulate the heart to contract. This is helpful for clinically stable patients who are at risk of decompensating rapidly, such as patients who are waiting to receive cardiac surgery, patients who will soon have a permanent pacemaker installed, or people with acute myocardial infarction who are showing early signs of a heart attack.
Cardioversion is another procedure that involves sending electrical shocks to the heart via electrode pads on the patient’s chest. In many cases, cardioversion quickly restores a normal rhythm in patients with arrhythmias or tachycardia.
When Should a Manual Defibrillator Be Used?
Because manual defibrillators provide a customized electrical shock, they should ONLY be used by medical professionals trained in advanced cardiac life support (ACLS). Delivering the correct shock requires an in-depth knowledge of heart rhythms and the ability to interpret electrocardiogram (ECG/EKG) data quickly and accurately.
In many cases, EMS personnel will use a manual defibrillator on a sudden cardiac arrest victim once they are transferred to the ambulance or hospital. Manual defibrillators are also the most appropriate medical devices to use on babies under one year old who are suffering from sudden cardiac arrest.
Cardiac arrest in children over one year old can be treated effectively with an AED. Simply switch the device to a pediatric setting with a pediatric key (if using a device like the Philips HeartStart FRx), pediatric button (if using a device like the LIFEPAK CR2), or pediatric pads (if using most other devices—like the HeartSine Samaritan PAD 350P, for instance).
Advantages of Manual Defibrillators
There are several advantages of using manual defibrillators, which is why they are such an important tool for medical professionals who provide advanced cardiac life support.
The first advantage is that using a manual defibrillator can reduce the interruption to cardiopulmonary resuscitation to only a few seconds as opposed to up to a minute for an automatic defibrillator. This is because a medical professional can assess the ECG data faster than a machine can.
The second advantage is that they can be used to provide appropriate electric shocks to babies. Please note that when a manual defibrillator is not available, chest compressions (with rescue breaths if the rescuer is trained) can be used to help keep babies alive until emergency medical services arrive.
The two main disadvantages of manual defibrillators are:
- The operator may deliver an inappropriate electrical shock, which is why it’s essential they are only used by professionals who are trained in ACLS and never by a lay rescuer. If there’s no shockable rhythm, or if the level of shock is inappropriate for the patient, the patient may lose their life.
- Manual defibrillators are not considered public access devices and as such are only available in medical settings such as hospitals and ambulances. In contrast, AEDs, by law, must be made available in most institutions and many commercial settings where people gather or engage in strenuous exercise.
AEDs and Manual Defibrillators Can Be Used Together
When it comes to AEDs and manual defibrillators, it’s not all or nothing. A patient can be switched over from an AED to a manual defibrillator or the two can be used together.
If the AED and manual defibrillator are made by the same manufacturer, the electrode pads can simply be unplugged from the AED and plugged into the manual defibrillator.
If the medical devices are made by different manufacturers, they can be connected via a cable to access the capabilities of the manual defibrillator without interrupting chest compressions or the analysis of the patient’s heart.
AEDs: Best for the Lay Rescuer
Having answered the question, “What is a manual defibrillator?”, the most important takeaway is that AEDs are usually sufficient for addressing sudden cardiac arrest in the community until medical professionals arrive. At that point, the experts can switch over to a manual defibrillator to provide advanced cardiac life support.
If you ever see someone collapse and become unconscious, the best thing you can do is call for an AED, call 9-1-1, and begin chest compressions immediately. While there is more that can (and will need to) be done, your timely action could save a life.