Static & Dynamic Lung Volumes Lab 6

Spirometer n Classic instrument for measuring air volumes – Wet- Consists of an air collecting bell inverted in a vessel of water Amount of water displaced gives you estimate of the air required to displaces it

Spirometer n Useful for static volume measurement – Vital capacity – Peak airflow n Limited usefulness when measuring rapid volume changes- speech – Inertia of the bell – Sluggish response – Total volume is not obscured but breath group data is!

Chest Wall Measurement n Lung volume can be determined from changes in rib cage and abdominal size n Devices for transducing size changes: – Magnetometers – Mercury strain gauges – Inductance plethysmography – Respitrace

Chest Wall Measurement n Chest wall’s 2 parts (rib cage & abdomen), Contribute to the total lung volume change – Rib cage and abdomen movement are not 1:1 so calibration of abdomen & rib cage are completed

Normal Adult- 20 year old Male V tl Red= LV Green= RC Blue = AB Yellow= Audio

Normal Adult- 20 year old Male V tl RC AB Audio LV

Red= LV Green= RC Blue = AB Yellow= Audio Lt. Blue = Orange = P t Multihandicapped Adult- 36 year old Male

V tl PtPt LV RC AB Audio

Articulatory & Phonatory Volumes n Specific articulatory events & phonatory tasks can be measured by: – Spirometer- Although not accurate enough n Poor resolution & frequency response – Respitrace- Also not accurate enough n Poor time resolution – Pneumotachograph n Integration of the flow signal to get volume n Shows very small volume changes in a fraction of a second

Pneumotachograph vs. Spirometer Greater squareness of the corners indicate better frequency response

Air Volume Measurements n Volume is calculated by multiplying mean flow by the event’s duration –.123 (flow) x 20 (duration)= 2.46 L (volume) – Not always the most accurate method for measuring articulatory volumes

Laboratory n Purpose: – Measure a patient's forced vital capacity (FVC) – Evaluate maximum phonation volume – Derive estimates of mean airflow from a volume record – Estimate lung volume used for each breath group during reading of a standard passage (in absolute terms and as a %age of FVC)

Laboratory n Part I- – FVC= maximum amount of air that can be expired after a maximal inspiration- represents the total amount of air that is available for use. – Measure height of patient – Measure FVC with spirometer or aerophone n Max. inhalation at REL, then max exhalation n 3 trials n Determine patient’s expected FVC (norms or formula in Appendix G

Laboratory n Part II: – Phonation volume (PV)= the maximum amount of air that is available for a maximally sustained phonation – Use sample (figure A) of sustained / a / for the lab questions n Is PV normal (Use norms in text) n Abnormal PV might occur in which pathological conditions? – For the patient exercise do a sustained / a / on the aerophone, mark it and calculate volume.

Laboratory n Part III: – Assessment of lung volume change during a speaking task (how a patient manages air for speech purposes) – Duration & relative volume of each breath group (amount of air expressed as a %age of VC) – Mark speaking record n Use Figure B

Laboratory – Analysis questions for part III: n Find REL- draw line across bottom of cycle n Divide into 10 equal segments (10% each) n Mark each breath group n The FVC for this sample will be ? n To calculate %age of VC: – Volume (in Liters) x 100 / VC in L – ex..64 x 100/ 4.4= 14.5%

Laboratory n Mean airflow data – Used to assess more general characteristics of ventilatory, laryngeal and/or articulatory function – Mean speech airflow= volume of air the speaker uses divided by the duration of the utterance

Laboratory n Part IV: – Use Figs. 3 & 4 of the running speech samples and highlight the mean flow rate from your calculations n baseline volume= where speech begins n Finishing volume= where speech ends n Total volume= baseline volume-finishing volume n Speech volume of each breath group & expiration duration n Mean airflow rate= mean speech volume/mean duration