In an operating theatre, much of the equipment exists to protect the health of the patient. Equally important, however, is protection of the health of the medical staff, but this barrier must not impair their vision or freedom of movement.
A surgical protection suit is the doctorís first and most important line of defense. An important element of the suit is the helmet, as this provides clean, uncontaminated air for the surgeon to breathe, and a protective visor that offers a clear and unobstructed view of the patient without misting.
Todayís most advanced surgical helmets include a powerful LED light to illuminate the area of the patientís body that the surgeon is focused on, and a multi-speed fan to ventilate both the helmet and the body of the suit. Since the surgeon requires complete freedom of movement, the suit cannot be tethered to a main power supply. A high-tech surgical protective suit will therefore include a battery power unit. The latest helmet includes a custom lithium-ion battery pack from Varta Microbattery that balances the constraints of size, weight, run-time, and reliability.
An important element of the suit is the helmet, as this provides clean, uncontaminated air for the surgeon in the operating theatre to breathe. A protective visor offers a clear and unobstructed view of the patient without misting.
Challenging combination of design requirements
The portable power supply in a surgical helmet must balance a number of apparently opposing requirements.
A complex medical operation can last for several hours. If the power in the helmet failed -- which would cause the LED light to dim and the visor to become misted as the fan stopped working -- the resulting interruption to the surgeonís activity could cause serious harm to the patient. The battery pack must therefore offer high energy capacity to sustain continuous operation over many hours, and predictable power delivery. The theatre crew must be able to read out the State of Charge (SoC) of the battery, and to estimate accurately the remaining run-time on the basis of the SoC value.
In general, the bigger the battery, the greater its energy capacity and the longer its run-time between charges. But at the same time, the helmet must be light and comfortable, since the surgeon will wear it for long periods. The battery pack must therefore be as small and light as possible. It must also be capable of tolerating the difficult conditions inside a protective suit: high humidity caused by vapor in the wearerís exhaled breath, as well as potential exposure to contaminants and high temperatures.
Finally, compliance with FDA regulations governing end products requires that suppliers of key components such as power supplies verify or validate that their products perform as specified, to within precisely defined tolerances.