# How CPAP Machines Gradually Increase Air Pressure for Sleeping Patients > A 1993 patent describing a CPAP machine that lets patients choose how slowly the air pressure ramps up to their therapeutic level, making it easier to fall asleep. - **Patent:** US 5199424 - **Original title:** Device for monitoring breathing during sleep and control of CPAP treatment that is patient controlled - **Owner:** Individual - **Granted:** 1993 - **Status:** Public domain (expired) - **Times cited:** 231 - **Field:** consumer_electronics, mechanical ## What it does This patent describes a method and device for Continuous Positive Airway Pressure (CPAP) therapy. It allows a patient to set a 'ramp' period, where the machine starts at a low, comfortable air pressure and gradually increases to the required therapeutic level over a period of time selected by the user. The device uses a delay timer mechanism to automate this transition, ensuring the patient is not blasted with full therapeutic pressure while they are still trying to fall asleep. Once the timer expires, the machine maintains the preset therapeutic pressure to keep the airway open throughout the night. ## What it does NOT cover - Does not cover automatic pressure adjustment based on real-time detection of snoring or breathing sounds. - Does not cover systems that adjust pressure based on inhaled air flow volume or rate. - Does not cover non-CPAP respiratory devices that do not use a sealed mask or nasal prongs. - Does not cover methods that lack a user-selectable variable time period for the pressure ramp. ## The clever bit The innovation lies in shifting the control of the therapy's onset to the patient, recognizing that psychological comfort during the transition to sleep is just as critical to treatment success as the physical pressure itself. ## Real-world examples 1. Ramp feature on ResMed AirSense 10 2. SmartRamp settings on Philips DreamStation 3. Standard CPAP machines with user-defined ramp timers ## Why it matters Before this invention, CPAP machines often delivered full pressure immediately, which many patients found uncomfortable or intolerable, leading to low compliance. By introducing the 'ramp' feature, this patent helped make CPAP therapy a viable, long-term treatment for obstructive sleep apnea. It is a foundational concept in modern sleep medicine that significantly improved patient adherence to treatment. ## Frequently asked questions ### What does How CPAP Machines Gradually Increase Air Pressure for Sleeping Patients cover? A 1993 patent describing a CPAP machine that lets patients choose how slowly the air pressure ramps up to their therapeutic level, making it easier to fall asleep. ### Who owns patent US 5199424? Individual owns this patent, granted in 1993. ### 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 5199424 cited by? This patent has been cited by 231 later patents that build on its ideas. ### What problem does this patent solve? Before this invention, CPAP machines often delivered full pressure immediately, which many patients found uncomfortable or intolerable, leading to low compliance. By introducing the 'ramp' feature, this patent helped make CPAP therapy a viable, long-term treatment for obstructive sleep apnea. It is a foundational concept in modern sleep medicine that significantly improved patient adherence to treatment. ### What does this patent NOT cover? Does not cover automatic pressure adjustment based on real-time detection of snoring or breathing sounds. **Full plain-English explainer:** https://patentbrief.org/patent/us/5199424/cpap-sleep-apnea-sullivan **Original patent:** https://patents.google.com/patent/US5199424 --- _Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._ ## Related patents Semantically similar inventions in the PatentBrief corpus: - [How Dr. Forrest Bird's Mechanical Respirator Controls Patient Breathing](https://patentbrief.org/patent/us/3191596/bird-respirator-ventilator) — A 1965 patent describing a mechanical ventilator that automatically switches between inhaling and exhaling based on pressure levels in a patient's airway. - [How the Iron Lung Artificial Respirator Works](https://patentbrief.org/patent/us/1906844/iron-lung-respirator-drinker) — A 1933 patent for a mechanical respirator that uses external air pressure changes to force a patient's lungs to expand and contract. - [How Vacuum Tubes Detect Tiny Changes in High-Resistance Sensors](https://patentbrief.org/patent/us/3735375/smoke-detector-ionization) — A 1973 circuit design using a vacuum tube to detect microscopic resistance shifts in sensors like ionization chambers, commonly used in early smoke detectors. - [How the Aqua-Lung Scuba Regulator Works](https://patentbrief.org/patent/us/2485039/aqualung-scuba-cousteau-gagnan) — The foundational 1947 patent by Jacques Cousteau and Emile Gagnan for the automatic demand regulator that allows divers to breathe compressed air underwater. - [Leonarde Keeler's Early Mechanical Blood Pressure Recorder](https://patentbrief.org/patent/us/1788434/polygraph-lie-detector-keeler) — A 1925 invention by Leonarde Keeler designed to mechanically record a patient's arterial blood pressure over time.