NOTICE: No human trials have yet been performed. This device has not been submitted to the FDA for regulatory clearance or approval. Statements about efficacy are meant to communicate intended therapeutic and safety benefits.


The Safe Positive Airway Pressure (SPAP) system is a custom valve and filter assembly that works with non-invasive ventilation systems like CPAP, BiPAP, VPAP or APAP (“PAP systems”) to capture and filter all exhalations. It permits positive pressure and oxygen therapy to be conveniently delivered to a patient while it protects caregivers from aerosolized virus.

The SPAP valve incorporates an internal pressure-relief valve that limits mask pressure rise when the patient coughs or sneezes to prevent leaks at the mask seal. This pressure-limiting function is also intended to protect patients from pressure-induced trauma to the lungs during coughing or sneezing. All exhalations are filtered through 0.3-micron viral filters before entering the room environment.

The addition of the SPAP to a standard PAP system leverages the ease-of-use and safety record of such systems and offers a practical, early-intervention option for COVID patients (or other patients with infectious respiratory diseases) in home or step-down facility settings.

Positive pressure and oxygen therapy both increase blood oxygen saturation levels and buy time for drug therapies and the patient’s own immune system to respond to the virus. The patient can remain at home, in a familiar, low-stress environment with the confidence that their caregivers and family members are protected. The SPAP valve in conjunction with PAP devices is not intended as a substitute for a mechanical ventilator. It is intended for patients who can still breathe spontaneously, but who are at risk of hypoxemia as determined by their physicians.

In addition to the possibility of the SPAP system delaying or avoiding the need for mechanical ventilation, it may allow earlier weaning of patients from mechanical ventilators, thereby freeing up existing ventilators and ICU resources to treat more acute patients.

NOVO Engineering has demonstrated feasibility with the first-generation system shown here and is now working on next-generation implementations. Bench test data has demonstrated that the PAP device function with oxygen enrichment performs as expected, and that the mask does not leak during coughing or sneezing. Clinical experts have responded enthusiastically and expressed the need for this device to be made available for COVID-19 patients.

We are now looking for clinicians interested in testing this device on patients—with appropriate IRB clearance—so that protocols and indications for use can be developed.

If you can help, please contact us immediately.

NOVO is an ISO 13485 certified medical device development company founded in 2004.


NOVO is continuing the design and development of the SPAP. The first-generation design is being made available free of charge on this website. We are seeking immediate clinical engagement to provide feedback that we will incorporate into our next-generation designs.

NOVO-RAD Fact Sheet X03
NOVO RAD 04 19 2020


  • Protects caregivers from contaminated exhalations and coughs
  • Provides non-invasive, oxygen-enriched, positive pressure therapy to patients
  • Purges CO2 to minimize rebreathing
  • May delay the need for an ICU ventilator and/or allow patients to be weaned from a ventilator sooner
  • May be suitable for home use under the care of a respiratory therapist or physician
  • Assembled from standardized components and easily fabricated custom parts without the need for expensive tooling
  • Available as an open-source design for rapid deployment and localized distribution


The SPAP uses standard CPAP, BiPAP, VPAP, or APAP equipment as the fresh air source and adds oxygen enrichment. The fresh air and oxygen mixture flows through the inlet side of the custom wye valve assembly. The mask port of the wye valve assembly connects to the mask elbow, and the exhaust port of the wye valve assembly is connected to the filter assembly. Valves within the wye valve assembly direct the flow of the enriched air mixture and exhaled breath during the breathing cycle. See the system schematic and drawings below.

Not Breathing:
When breathing is paused, air/O2 mix flows directly from inlet to outlet through flow restrictions. This establishes the baseline mask pressure. Inhale: Most air/O2 mix flows into the lungs; a residual amount flows through the restrictions, ensuring positive pressure during inhaling. Exhale: The air/O2 mix combines with the exhaled breath, increasing flow though the restrictions, and mask pressure rises. Cough or Sneeze: The sudden pressure rise opens the cough valve and causes the inlet valve to close; the cough valve limits pressure rise in the mask so the mask does not separate from the face and leak virus into the room.



When pressure spikes during coughs (shown at right of the graph below), the over-pressure valve opens and limits the pressure in the mask to a level that keeps it from lifting off of the patient’s face and broadcasting the virus into the room environment. The lack of a change in slope of the curves during cough is an indication that the mask is not leaking.


We urgently request your support.

Please contact us immediately to discuss clinical engagement.

Clinical considerations for device usage:

  • Works with standard CPAP or bi-level positive pressure therapy equipment.
  • Compatible with any non-vented, full face mask that has a 22mm male elbow.
  • All exhaled breath is contained and filtered through viral filters before being allowed to escape into the room.
  • The filter assembly can be configured for two or more viral filters in parallel. It is intended to be zip-tied to a bed rail and may incorporate a drain valve at the bottom for condensate if a humidifier is being used.
  • Aerosolized drug therapies can be introduced by splicing in a T or Y connector into the oxygen line connected to the oxygen port on the SPAP valve.
  • A cough valve is incorporated to limit mask pressure when the patient sneezes or coughs, thereby preventing the mask from lifting and breaking the seal with the patient’s face.
  • Operation of this system is as simple as using a CPAP or BiPAP machine.
  • A mask pressure tap can be connected to a pressure monitor and alarm device.
  • Constant purge flow and low dead volume prevent rebreathing of CO2.
  • Planned refinements and upgrades include an anti-asphyxiation valve, integration with a closed-suction catheter, and optimization of the cough valve.


In addition to its open-source nature, we have designed our SPAP to be manufactured without any tooling required and from readily available materials and components. The design relies on simple die-cut or hand-cut valve elements, 3D-printed components, and commonly available, standardized components used for CPAP equipment. It is streamlined, integrated, and easy to assemble.


We are seeking to recruit regional medical device manufacturers to build product for their local hospital systems. We need to have manufacturing capacity lined up once the therapeutic benefit of the SPAP device is confirmed.

Please contact us immediately if you are a medical device manufacturer willing to help your local community.


Thanks to our colleague Steve Harrington at Flometrics who began this quest and invited us in. They are now working on a DIY mechanical ventilator design. We encourage you to visit their site.