How Dr. Forrest Bird's Mechanical Respirator Controls Patient Breathing
A 1965 patent describing a mechanical ventilator that automatically switches between inhaling and exhaling based on pressure levels in a patient's airway.
Original patent title: “Respirator”
A 1965 patent describing a mechanical ventilator that automatically switches between inhaling and exhaling based on pressure levels in a patient's airway. Granted to Individual in 1965 with 2 claims and 78 forward citations, and it is now in the public domain.
Coverage
What does this patent actually cover?
The device acts as an automated breathing controller that connects a pressurized gas source to a patient's airway. It uses a main valve to toggle between inhalation and exhalation phases. The system monitors the air pressure at the patient's airway; when the pressure hits a specific threshold, the controller automatically closes the valve to end inhalation. If the pressure fails to reach that threshold within a set time, a secondary valve system triggers an additional flow of gas to ensure the patient receives the required volume of air.
The gap
What does this patent NOT cover?
- Does not cover electronic or microprocessor-based control systems.
- Does not cover non-pressure-sensitive ventilation methods.
- Does not cover portable manual resuscitation bags (Ambu bags).
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
Key facts
What made this novel
The invention uses a fail-safe pneumatic timer that detects when a patient is not receiving enough pressure, automatically injecting extra gas to maintain the breathing cycle.
The Patent Drawing
Schematic visualization of the patent's claim structure. Hand-drawn diagrams in progress for each landmark patent.
Where you've seen this
Real-world examples
Bird Mark 7 respirator
Hospital mechanical ventilators
Emergency medical transport ventilators
Why it matters
The bigger picture
This patent represents a foundational step in modern critical care medicine. Forrest Bird's inventions moved ventilation from bulky, iron-lung style machines to portable, reliable devices that could be used in ambulances and emergency rooms, saving countless lives during respiratory failure.
Filed
September 19, 1960
Granted
June 29, 1965
Market context
Who's building on this
Companies in this space
Companies like Hamilton Medical, Dräger, and GE Healthcare continue to build on the principles of pressure-cycled ventilation established by Bird. These manufacturers have evolved the pneumatic logic into sophisticated digital systems that monitor patient lung compliance in real-time.
Market impact
This technology effectively launched the modern field of respiratory therapy. It standardized the use of pressure-cycled ventilators in hospitals, moving the industry away from manual ventilation and enabling the development of the intensive care unit (ICU) as a standard hospital department.
Claim 1 — Plain English
What this patent covers
The device acts as an automated breathing controller that connects a pressurized gas source to a patient's airway. It uses a main valve to toggle between inhalation and exhalation phases. The system monitors the air pressure at the patient's airway; when the pressure hits a specific threshold, the controller automatically closes the valve to end inhalation. If the pressure fails to reach that threshold within a set time, a secondary valve system triggers an additional flow of gas to ensure the patient receives the required volume of air.
The clever bit
The invention uses a fail-safe pneumatic timer that detects when a patient is not receiving enough pressure, automatically injecting extra gas to maintain the breathing cycle.
What it does not cover
- Does not cover electronic or microprocessor-based control systems.
- Does not cover non-pressure-sensitive ventilation methods.
- Does not cover portable manual resuscitation bags (Ambu bags).
Patent timeline
Application submitted to the patent office
Application published, typically 18 months after filing
Patent officially issued
Patent enters public domain
This patent is in the public domain
See the Freedom to Build guide — what is free to use, what is not, and how to cite this patent.
PatentBrief Score
Impact Score
Early stage
Citation count
38/40
Highly cited
Claim breadth
1/20
Narrow claimsclaimsThe numbered statements at the end of a patent that legally define what the inventor owns.Read more →
Recency
0/20
Older than 20 years
Assignee scale
0/20
Independent or smaller assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more →
PatentBrief Impact Score — based on citation count, claim breadth, recency, and assignee scale. Not a legal assessment.
Heuristic Value Estimate
What this patent might be worth
$48K – $152K
Midpoint $95K · expired or expiring · industry ×2.2
Heuristic only — blends forward/backward citation counts, claim scope, time remaining, litigation history, and CPC-derived industry baseline. Real valuations need a professional appraisal.
Patent Claims
1 independent claim · 0 dependent
Claims are the legal boundaries of the patent. An independent claim stands alone. A dependent claim adds limitations to its parent, narrowing — but not broadening — the scope.
The original legal language
Original claims
2 claims as filed with the patent office.
Concepts involved
Citations
Patent lineage
Cite this patent
Bird, F. M., & Pohndorf, H. L. (1965). How Dr. Forrest Bird's Mechanical Respirator Controls Patient Breathing (U.S. Patent No. 3,191,596). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/3191596/bird-respirator-ventilator
Auto-generated from the patent record. Double-check author order and the issue date against the official USPTO document before submitting.
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Common Questions
Frequently Asked Questions
What does How Dr. Forrest Bird's Mechanical Respirator Controls Patient Breathing cover?
A 1965 patent describing a mechanical ventilator that automatically switches between inhaling and exhaling based on pressure levels in a patient's airway.
Who owns patent US 3191596?
Individual owns this patent, granted in 1965.
When does this patent expire?
This patent has expired and is now in the public domain — anyone can use the invention freely.
What is patent US 3191596 cited by?
This patent has been cited by 78 later patents that build on its ideas.
What problem does this patent solve?
This patent represents a foundational step in modern critical care medicine. Forrest Bird's inventions moved ventilation from bulky, iron-lung style machines to portable, reliable devices that could be used in ambulances and emergency rooms, saving countless lives during respiratory failure.
What does this patent NOT cover?
Does not cover electronic or microprocessor-based control systems.
Same assignee
More from Individual
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