Biphasic Defibrillator vs. Monophasic Defibrillator

What's the Difference?

Biphasic defibrillators and monophasic defibrillators are both medical devices used to deliver an electric shock to the heart in order to restore a normal heart rhythm during cardiac arrest. The main difference between the two lies in the waveform of the electric shock they deliver. Monophasic defibrillators deliver a single waveform, while biphasic defibrillators deliver a two-phase waveform. Biphasic defibrillators have been found to be more effective in achieving successful defibrillation with lower energy levels, resulting in less damage to the heart tissue. Monophasic defibrillators, on the other hand, require higher energy levels and may cause more tissue damage. Overall, biphasic defibrillators are considered to be more advanced and efficient in delivering effective shocks for cardiac arrest patients.


AttributeBiphasic DefibrillatorMonophasic Defibrillator
WaveformBiphasic waveformMonophasic waveform
Energy DeliveryDelivers energy in two phases (positive and negative)Delivers energy in a single phase (positive or negative)
EffectivenessMore effective at defibrillation with lower energy levelsLess effective at defibrillation, higher energy levels required
Energy ControlAllows for energy control and adjustmentEnergy level is fixed and cannot be adjusted
Shock DurationShorter shock durationLonger shock duration
SizeSmaller and more compactRelatively larger in size
CostGenerally more expensiveRelatively less expensive

Further Detail


Defibrillators are life-saving medical devices used to restore normal heart rhythm in individuals experiencing cardiac arrest. There are two main types of defibrillators: biphasic and monophasic. While both serve the same purpose, they differ in terms of waveform, energy delivery, and effectiveness. In this article, we will explore the attributes of biphasic and monophasic defibrillators, highlighting their advantages and limitations.

Biphasic Defibrillator

A biphasic defibrillator delivers an electrical shock to the heart using a two-phase waveform. The waveform consists of a positive and negative phase, which allows for the flow of current in two directions. This design enables the biphasic defibrillator to deliver a more efficient and effective shock compared to its monophasic counterpart.

One of the key advantages of biphasic defibrillators is their ability to achieve successful defibrillation at lower energy levels. The biphasic waveform optimizes the delivery of energy to the heart, resulting in higher success rates with lower energy doses. This is particularly beneficial for patients with sensitive hearts or those who may be more susceptible to complications from high-energy shocks.

Biphasic defibrillators also offer a higher first-shock success rate compared to monophasic defibrillators. The two-phase waveform allows for better penetration of the myocardium, ensuring effective depolarization and subsequent restoration of normal heart rhythm. This increased success rate reduces the need for multiple shocks, minimizing the potential for tissue damage and improving patient outcomes.

Furthermore, biphasic defibrillators are generally more compact and portable, making them suitable for various healthcare settings, including ambulances, hospitals, and clinics. Their smaller size and lighter weight enhance their ease of use and mobility, enabling healthcare professionals to quickly respond to cardiac emergencies.

However, biphasic defibrillators may have a higher initial cost compared to monophasic defibrillators due to their advanced technology and design. Additionally, the availability of biphasic defibrillators may be limited in certain regions or healthcare facilities, which could impact their accessibility.

Monophasic Defibrillator

A monophasic defibrillator delivers an electrical shock to the heart using a single-phase waveform. Unlike biphasic defibrillators, which have two phases, monophasic defibrillators deliver energy in only one direction. While monophasic defibrillators have been widely used for many years, their usage has decreased with the introduction of biphasic defibrillators.

Monophasic defibrillators are known for their simplicity and reliability. They have a straightforward design and are relatively easy to operate, making them suitable for healthcare professionals with varying levels of experience. The single-phase waveform delivers a high-energy shock to the heart, which can effectively restore normal heart rhythm in many cases.

One advantage of monophasic defibrillators is their lower initial cost compared to biphasic defibrillators. This affordability makes them more accessible to healthcare facilities with limited budgets or resources. Additionally, monophasic defibrillators are widely available and can be found in most healthcare settings, ensuring their availability in emergency situations.

However, monophasic defibrillators generally require higher energy levels to achieve successful defibrillation compared to biphasic defibrillators. The single-phase waveform may result in less efficient energy delivery, requiring higher energy doses to effectively depolarize the myocardium. This can increase the risk of tissue damage and potential complications for patients.

Moreover, monophasic defibrillators have a lower first-shock success rate compared to biphasic defibrillators. The single-phase waveform may not penetrate the myocardium as effectively as the biphasic waveform, leading to a higher likelihood of unsuccessful defibrillation attempts. This can prolong the time required to restore normal heart rhythm and may necessitate additional shocks.


In conclusion, both biphasic and monophasic defibrillators play a crucial role in the management of cardiac arrest. Biphasic defibrillators offer several advantages, including lower energy requirements, higher first-shock success rates, and enhanced portability. However, they may have a higher initial cost and limited availability in certain regions. On the other hand, monophasic defibrillators are simpler, more affordable, and widely available, but they require higher energy levels and have lower first-shock success rates.

Ultimately, the choice between biphasic and monophasic defibrillators depends on various factors, including the specific needs of the healthcare facility, patient population, and available resources. Healthcare professionals should carefully consider these attributes and consult with experts to determine the most suitable defibrillator for their setting, ensuring optimal outcomes for patients experiencing cardiac arrest.

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