CPAP Remote Alarm System

BME 272: Oral Report Four

Group 15Kathleen Grunder

Jessica PaulsenMolly Rice

Project Advisor Dr. Roberta Leu - Clinical Instructor in the

Sleep Disorders Division of Neurology, Vanderbilt University

Academic Advisor Dr. Paul King - Professor of Biomedical

Engineering Emeritus, Professor of Mechanical Engineering Emeritus

• Most common form of sleep disorder breathing• 2% of US children have been diagnosed with

obstructive sleep apnea• Results in partial or complete collapse of the

upper airway• Can lead to sleep deprivation, arrhythmia, high

blood pressure, heart disease, stroke, or death•  80% of children have apnea that can be

treated with corrective surgery

Obstructive Sleep Apnea

•  Used to treat sleep apnea in the 300,000 US children whose apnea cannot be corrected with surgery

•  Holds airway open with continuous flow of air

•  Effective when used correctly 

Constant Positive Airway Pressure (CPAP) Therapy

• Continuous Positive Airway Pressure (CPAP) machine masks often slip off during the night; this can be especially dangerous for children, who are not compliant with wearing the mask

Analysis Problem Statement

• There is currently no alarm to alert parents when their child's CPAP machine has failed

• "I'm very nervous about knowing when [the mask] comes off because I realize how important it is to keep [my son's] airway open." - Parent of a child with sleep apnea

• A patent search and literature review found mask displacement alarmso none remoteo none with our proposed mechanisms

AnalysisPerformance Criteria

• To develop a remote alarm system to wake parents when their child’s CPAP machine has failed

AnalysisPrimary Objective

• Source power failure• Disconnected power cord• Internal machine failure• Mask displacement • Mask removal • Hose disconnectiono From mask o From machine

• Kinked hose• Punctured hose

AnalysisFailure Modes

Failure Mode Diagram

Hose FailureMask

DisplacementInternal Failure Power Failure

Airflow Decreases

Airflow Increases

Propeller Spin Rate Breaches Specific Range

Alarm Sounds in Parents’

Room

Parent Replaces

Child’s Mask

• To improve pediatric compliance with CPAP masks

• To prevent complications from apneas that can occur when the machine fails

• To alert parents when the machine failso To provide parents with comfort in knowing that

the machine is working properly

HypothesisGoals

• To use an airflow sensor (spinning propeller/ interrupter) to determine when the airflow is outside a determined range indicating that one of the failure modes has occurred

HypothesisSolution Description

Preliminary Design 

• Sensitivity measurementso How often does the machine sound when the mask is off?

• Functionalityo Does the alarm go off when the machine fails?

• Complianceo Do parents and children use the alarm?

• Alarm Volumeo Does the alarm wake up the parents?

• Receiver Rangeo Can the reciever get the signal all over a house?

HypothesisPerformance Metrics

• Met with sales representatives from ResMed, a CPAP manufacturer

• Obtained CPAP machine and three masks from ResMed

• Consultation with Dr. Galloway • Obtained parts• Began constructing circuit

Progress Completed Work

• Finish constructing circuit• Design corresponding LabView VI• Begin testing sensor segment

ProgressCurrent Work

• Begin building and testing alarm segment

• Perform cost analysis• Build business plan

ProgressFuture Work