Pressure to Resuscitate

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 to Resuscitate

Unless you have had specific training, what you know about cardiopulmonary resuscitation (CPR) may be based on what you have seen on television or in a movie. You push on the unresponsive patient’s chest when they are not breathing. The compressions (pressure on the chest) take the place of a non-beating heart to keep blood flowing.

According to “Technique for chest compressions in adult CPR,” “Chest compressions have saved the lives of countless patients in cardiac arrest as they generate a small but critical amount of blood flow to the heart and brain.”

And, unlike other medical actions, chest compressions can be initiated by any healthcare provider without a physician’s order.

First aid response for CPR

First aid response for CPR
Image source: Science Photo Library.

For those not trained in CPR, the American Heart Association recommends hands-only CPR: uninterrupted chest compressions of 100 to 120 a minute until paramedics arrive. This means pushing straight down to compress the chest using your upper body weight (not just your arms) at least 2 inches (or about 5 centimeters) but not greater than 2.4 inches (about 6 centimeters). With the compression, the heart is squeezed and increases both the aortic and the right atrial pressures. Normal aortic pressures during systole (from the time the aortic valve opens until the peak aortic pressure), range from 80 mmHg to 120 mmHg. So how much pressure is required for the heart and for the brain in CPR? In a laboratory environment, researchers continue to explore the implications to improve the outcomes of CPR.

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Pop goes the Chip Bag

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.

Pop goes the Chip Bag

Transitioning from lower altitude to a higher altitude decreases the pressure on a sealed container. Normally this would be recognized by the bloated appearance of the product in a sealed bag and a rapid release of the pressurized air inside when the bag is opened.  However, if the bag’s seal is weak, the bag can explode with a surprisingly load pop, en route.

This occurred recently on a trip where the altitude changed from 1248 feet to 7500 feet. Taking the temperature difference into account, the external air pressure changed from 14.08 psi (97.8 kPa) to 11.25 psi (77.6 kPa). This resulted in the decrease in external pressure of 2.83 psi (20.2 kPa or 78.3 inches of water) – sufficient to explode the weak seal.

Surprisingly, this wasn’t the only time that a bag of the same brand of chips lost its seal during the same trip but previously the bag did not explode. Since several other brand of pretzels and other munchies did not experience a bag failure during many trips, it appears that a little product line pressure testing during packaging is in order to minimize a weak seal.

Air Pressure in a Chip Bag

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Pressure in the Salmon Cannon

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 in the Salmon Cannon

Dams are helpful to control water flow in rivers but they pose a major problem for migratory fish like salmon. The dam restricts the salmon’s ability to swim upstream and spawn. In the United States alone, there are 85,000 dams. To solve the problem, Whooshh Innovations created its Fish Transport System, also called the Salmon Cannon.

With the Salmon Cannon, fish are either manually placed in a tube or slide in via a gravity slide below the dam. Then the soft tubing conforms to the size of the fish so a column of water does not have to be moved. Moving a column of water in, for example, a 1,700 feet project would require 0.433psi/ft x 1700ft = 736 psi.

In contrast, by conforming to the fish, they are essentially pushed through the system using an average of one to two psi. According to Whooshh CEO Vince Bryan III, “The system builds lower air pressure in front of the fish and more behind them with just a single blower motor, working just like a pneumatic tube at a bank.”

Based on independent studies that showed no scale loss, eye damage or other injuries, the amount of pressure safely transports fish from one area to another. The Whooshh tubes can handle a variety of fish sizes but generally transport fish between 2 and 34 pounds. In a typical system, the fish travel between 16 and 26 feet per second or about 18 miles per hour.

Whooshh Fish Cannon

Salmon fed into the Salmon Cannon below the dam transport through a tube to be safely returned to the water upstream, where they can continue their journey to spawn.
Source: The Guardian and Whooshh Innovations.

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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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Do you have a pressure sensing question? Let us know and we’ll address it in an upcoming blog.
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