Getting the Right Medical Room Pressure

Welcome to All Sensors “Put the Pressure on Us” blog. This blog brings out pressure sensor aspects in a variety of applications inspired by headlines, consumer and industry requirements, market research, government activities, and you.

Getting the Right Medical Room Pressure

With airborne infectious diseases that can easily spread from one person to another, such as the COVID-19 virus, isolation is critical. In a hospital or clinic, an isolation room needs negative pressure to have airflow into the room and avoid pathogens, or germs, from escaping. In addition to viruses, other undesirable contaminants to keep away from the rest of the population and sterile equipment in a hospital include bacteria, fungi, yeasts, molds, pollens, gases, volatile organic compounds (VOCs), small particles and chemicals.

The airflow to create and maintain the negative pressure (vacuum) in the room requires a consistent pressure differential of about 0.01 inch water gauge (in. w.g.) or 2.5 Pascals (Pa).

According to the Facility Guidelines Institute’s (FGI’s) most recent 2018 FGI Guidelines ANSI/ASHRAE/ASHE Standard 170-2017, other rooms that should be negatively pressurized include:

  • Emergency Department Public Waiting Areas
  • Emergency Department Decontamination
  • Radiology Waiting Rooms
  • Triage
  • Bathrooms
  • Airborne Infection Isolation (AII) Rooms
  • Most Laboratory Work Areas
  • Autopsy Rooms
  • Soiled Workrooms or Soiled Holding Rooms
  • Soiled or Decontamination Rooms in Sterile Processing Department
  • Soiled Linen Sorting and Storage
  • Janitors’ Closets

In contrast, protecting the patient and sterile medical and surgical supplies in an operating room requires positive pressure to keep undesirable contaminants outside. The positive pressure room is achieved by pumping in filtered, clean air.

Isolation (Low) vs. operating room (High) pressure

Isolation (Low) vs. operating room (High) pressure.
Source: Minnesota Department of Health

In fact, some portable, headgear-mounted air purifying respirator systems use positive pressure to protect the wearer.

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The Pressure for Ventilators

Welcome to All Sensors “Put the Pressure on Us” blog. This blog brings out pressure sensor aspects in a variety of applications inspired by headlines, consumer and industry requirements, market research, government activities, and you.

The Pressure for Ventilators

In addition to the pressure to get more ventilators, pressure is an integral part of a ventilator’s operation. Breathing involves inspiratory (inhaling) pressure and expiratory (exhaling) pressure and a ventilator has to take the user’s values into account. Peak Inspiratory Pressure or PIP is the maximum pressure inside the lungs during each inhaled breath and the normal range is 25-30 cm H2O. Positive End Expiratory Pressure or PEEP is the amount of pressure left inside the lungs at the end of a breath to keep the alveoli, tiny air sacs of the lungs, open. The normal range is 3-5 cm H2O.

The pressure inside a patient’s lungs depends on the compliance of their lungs. While the suggested range of pressures during ventilation is 20-35 cm H2O with an absolute maximum of 40 cm H2O, someone with damaged lungs may need a higher pressure.

 

Airway pressure and flow waveforms during constant flow volume control ventilation show PEEP and PIP

Airway pressure and flow waveforms during constant flow volume control ventilation show PEEP and PIP.
Source: http://rc.rcjournal.com/content/59/11/1773/tab-figures-data

With pressures below 50 cm H2O (19.7 in H2O or 4,903 Pa) for dynamic measurements, a pressure sensor designed specifically for these low pressures, such as All Sensors’ DLC, DLLR, and others, provide the required accuracy.

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Do you have a pressure sensing question? Let us know and we’ll address it in an upcoming blog.
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Protecting MEMS Pressure Sensors with Parylene

Welcome to All Sensors “Put the Pressure on Us” blog. This blog brings out pressure sensor aspects in a variety of applications inspired by headlines, consumer and industry requirements, market research, government activities, and you.

Protecting MEMS Pressure Sensors with Parylene

Microelectromechanical systems (MEMS) pressure sensors provide accurate measurements for many applications. However, the top side of the piezoresistive MEMS pressure sensor die that has the sensing elements and potentially other circuitry cannot survive exposure to many common items that need to have their pressure measured — including water. To isolate the top surface of the pressure sensor die and other exposed circuitry, parylene is often used as a protective coating. Applied by a vapor deposition polymerization process, the parylene allows pressure to be transmitted to the top side of the pressure sensor to make measurements without damaging or impacting the reliability of the circuitry. The conformal, thin-film coating provides a moisture, chemical and dielectric barrier to protect the sensor’s critical circuitry in medical, automotive and other applications.

In fact, parylene extends the applications that a specific sensor design can address and is part of the packaging expertise that a sensor company may provide. Parylene coating can be found on a wide variety of All Sensors’ products. Specifically, parylene coating is available in all miniature digital product families such as the miniature digital DLVR, DLHR and DLLR Series as well as the millivolt output MLV series and the miniature digital and analog ELVR series.

All Sensors' E1BD Package

 

A protective parylene coating is an option for moisture/harsh media protection in the DLVR, DLHR and DLLR Series E1BD package.

Comments/Questions?
Do you have a pressure sensing question? Let us know and we’ll address it in an upcoming blog.
Email us at info@allsensors.com

Pressure and Water Safety

Welcome to All Sensors “Put the Pressure on Us” blog. This blog brings out pressure sensor aspects in a variety of applications inspired by headlines, consumer and industry requirements, market research, government activities, and you.

Pressure and Water Safety

“Not (intended as) a life saving device” is commonly found on inflatable products that can be used in a pool, river, lake and even the ocean.  With the summer of 2019 well under way, most inflatables have already been pressurized so they can float and support the weight of even the heaviest person. However, when a new float is purchased or one found that wasn’t inflated, the user has the choice of using a pump or their lungs to add the necessary quantity of air. If a pump is not an option, the amount of air that must be blown into the device can be an issue, especially for a large float or for a person with limited lung capacity. For a large float, it could take a lot of time for the cumulative exhales to inflate it.

While it gets obvious when the float is near its limits, pressure is also an issue. Buoyancy or buoyant force is created by the difference between the pressure at the bottom of the float pushing it up and the pressure at the top pushing down. Archimedes principle and actual pressure measurements for flow and internal pressure could be brought into this discussion but it’s time to just relax and float around.

Yellow Pool Float

 

Comments/Questions?
Do you have a pressure sensing question? Let us know and we’ll address it in an upcoming blog.
Email us at info@allsensors.com