Concentrators

Introduction to Oxygen Concentrators

  • Definition: An oxygen concentrator is a common device used by patients at home to receive oxygen.

  • Function: It makes oxygen from ambient air through a process known as physical separation.

Mechanism of Oxygen Concentration

  • Process Overview:

    • Oxygen concentrators separate nitrogen and trace gases from atmospheric air, concentrating oxygen molecules into a final product tank.

  • Components:

    • Pump:

    • Draws in room air.

    • Filters and compresses the air.

    • Molecular Sieves:

    • Contains special pellets made from sodium aluminum silicate that absorb carbon dioxide (CO2), nitrogen, and water vapor.

    • Final Product Tank (Accumulator):

    • Collects concentrated oxygen.

Operation of Molecular Sieves

  • Functionality:

    • The sieves alternate between pressurizing and purging.

    • While one sieve pressurizes to concentrate oxygen, the other purges absorbed gases and moisture.

  • Purity Levels:

    • Oxygen purity in the accumulator ranges from 90% to 96%.

    • Studies indicate that as long as it’s above 85%, it closely approximates 99% purity.

  • FDA Regulations:

    • Hospitals require medical oxygen to be 99% pure; oxygen concentrators do not meet this standard.

Delivery of Oxygen to Patients

  • Connection to Patients:

    • Oxygen is delivered from the concentrator through a Christmas tree adapter connected to oxygen tubing.

  • Flow Meter:

    • Typically, the flow meter ranges up to 5 liters per minute.

    • The oxygen purity varies with the flow rates:

    • 1-2 liters/min: 92-95% purity

    • 3-5 liters/min: 85-93% purity

  • Combining Units for Higher Flow Rates:

    • For higher flow rates (>5 liters/min), two concentrators can be connected (e.g., both at 3 liters for 6 liters total).

Pressure Characteristics

  • Outlet Pressure:

    • Lower than tanks or hospital systems, rated at 5 to 10 psi.

    • Comparison:

    • Tanks and hospital systems operate around 50 psi.

Advantages of Oxygen Concentrators

  • Cost Efficiency:

    • Oxygen concentrators are cheaper compared to liquid oxygen systems.

    • No need for regular refilling; reduces the burden on home care companies.

  • Operational Heat:

    • Generates heat during operation, which can be a disadvantage in warmer climates as it increases room temperatures.

    • Could attract insects.

Backup Systems and Maintenance

  • Backup Systems:

    • Patients must have a backup oxygen cylinder (H tank or full E tank) for power outages.

  • Maintenance Responsibilities:

    • Patients are responsible for cleaning filters weekly to ensure optimal performance.

    • Molecular sieves require replacement periodically as tracked by an hour meter in the machine.

Monitoring Oxygen Output

  • Monitoring Equipment:

    • To verify FiO2 output, a leader meter can be used, functioning similar to a Thorpe tube.

    • An oxygen analyzer measures the purity of the outgoing oxygen.

  • Purity Standards and Alarms:

    • A purity drop below 85% necessitates replacement per manufacturer guidelines.

    • Alarms signal if:

    • Oxygen purity is too low.

    • Flow meter is inadvertently turned off.

    • There may be a delay in achieving optimal oxygen purity when the machine is turned on due to accumulation cycles.

Innovations and Portable Options

  • Refillable Concentrators:

    • Some concentrators may allow for home refilling from liquid oxygen tanks.

  • Portable Concentrators:

    • Offer greater freedom for patients, are FAA approved for air travel, and conveniently powered by batteries or car chargers.

  • Cost Considerations:

    • Portable concentrators range from $3,000 to $6,000 and are often not covered by insurance, making them expensive for patients on fixed incomes.