How often should defibrillation pads be changed?: the effect of evaporative drying

Area of Science:

• Cardiology
• Biomedical Engineering
• Medical Devices

Background:

• Water-based defibrillation pads improve conductivity but may dry rapidly.
• Rapid drying can increase transthoracic impedance (TTI), potentially affecting defibrillation efficacy.
• Assessing the impact of evaporative drying on TTI is crucial for patient safety.

Purpose of the Study:

• To evaluate the effect of evaporative drying of 3M defibrillation pads on transthoracic impedance (TTI).
• To determine the safe duration for defibrillation pad placement before significant TTI increase.

Main Methods:

• Transthoracic impedance (TTI) was measured in 20 adult males using 3M defibrillation pads.
• Measurements were taken at 5-10 minute intervals using a Bodystat MultiScan 5000 monitor at 30 kHz.
• Pad mass was recorded to quantify evaporative loss over time.

Main Results:

• Evaporative drying of pads began immediately and rapidly, causing significant mass decrease.
• A statistically significant increase in TTI (2.2%) was observed after 30 minutes, correlating with a 12.6% pad mass decrease.
• TTI continued to rise linearly after the initial 30-minute period.

Conclusions:

• 3M defibrillation pads can be safely used for at least 25 minutes in a standard hospital environment without significant TTI increase.
• Evaporative drying is a factor influencing TTI, but its impact is limited within the first 25 minutes.
• This finding supports current clinical practices regarding defibrillation pad application times.