Volume and Flow Measuring Devices

Volume Measuring Spirometers Wedge Bellows Collapsable bellows that folds and unfolds as patient [blank_start]breathes[blank_end] Will [blank_start]lose[blank_end] volume if cracks or holes in bellows Dry Rolling Seal Spirometer Volume Displacement Consists of a [blank_start]piston[blank_end] within a [blank_start]cylinder[blank_end] supported by a rod resting on a frictionless bearings Rod can be attached directly to a potentiometer or recording pen on paper Can be used to assess pre/post bronchodilator changes Water Seal Spirometer Volume Displacement AKA Collins or [blank_start]Steadwell[blank_end] Large bell [blank_start]7[blank_end]-[blank_start]14[blank_end] L, submerged in a column of [blank_start]H2O[blank_end] As pt breathes, bell moves an equally [blank_start]proportional[blank_end] distance Recorded with chain/pulley device connected to kymograph For rebreathing studies: [blank_start]separate[blank_end] hoses and [blank_start]CO2[blank_end] scrubber are needed Calibration: Using 3L syringer, must be accurate - range +- [blank_start]3.5[blank_end]% Leak Test: Filling spirometer to 1/2 volume then applying a [blank_start]weight[blank_end] Flow Cal: using [blank_start]rotameter[blank_end] 2-12 L/sec

Flow measuring Devices Peak flow meter Measure peak expiratory flow at [blank_start]bedside[blank_end] Pt inhales maximally then exhales hard and fast through deice PEFR is read directly from [blank_start]scale[blank_end] Factors that affect accuracy - Pt effort, [blank_start]Moisture[blank_end], Debris Turbine Device Wright Respirometer Rotating [blank_start]Vane[blank_end] with gears, flow causes vanes to [blank_start]spin[blank_end] and displays volume Accurate from 3-200 lpm Assure [blank_start]linearity[blank_end] by checking flows with 3L syringe Can become alinear from vane [blank_start]deformation[blank_end], contamination or debris

Pneumotach - measures flow and converts to volume display Ultrasonic Pneumotach AKA [blank_start]Vortex[blank_end] Shedding or Transit Time Consists of an emitting and recieving [blank_start]crystal[blank_end] and a lflow tube with struts Number of [blank_start]pulses[blank_end] is proportional to [blank_start]flow[blank_end] Pitot Tube Flow measured by placing a series of small [blank_start]tubes[blank_end] in a flow sensor and connecting to a pressure transducer Condensation and secretions [blank_start]do not[blank_end] affect measurements Thermal Element Contains heated [blank_start]platinum[blank_end] wire or small metal [blank_start]bead[blank_end] that [blank_start]cools[blank_end] as gas flows across. Amount of current needed to maintain tem is [blank_start]proportional[blank_end] to flow Accuracy is affected by gas [blank_start]composition[blank_end] Pressure Differential AKA Fleisch Pneumotach Contains [blank_start]resistive[blank_end] element that causes pressure to drop as gas flows across. Difference in pressure is [blank_start]proportional[blank_end] to flow Commonly used in Body Box Heat is incorporated to reduce [blank_start]condensation[blank_end]

CO2/Water Absorbers CO2 Absorbers Sodium [blank_start]Hydroxide[blank_end], NaOH (SodaLime, Soda-Sorb) BaraLyme, Barium Hydroxide Used for [blank_start]rebreathing[blank_end] tests, [blank_start]He[blank_end] Dilution or DLCO RB Replace: When exhausted, when color [blank_start]changes[blank_end], Weekly Produced H20 as a byproduct. Place upstream from H20 [blank_start]absorber[blank_end] Water Absorber Drie-Rite (calcium sulfate, CaSO4) Removes moisture from pt breathes through circuit When CO2 reacts with soda lime it produces H20 Place [blank_start]AFTER[blank_end] co2 absorber and before analyzer

Permapure Tubing ([blank_start]Fafion[blank_end]) Special tubing - conditions gas to equilibrate with [blank_start]ambient[blank_end] humidity Allows for accurate levels in gas samples Valves Directional Valves Allows tech to switch pt into [blank_start]circuit[blank_end] [blank_start]Directs[blank_end] exhaled gas through analyzers.spirometers

Calibration 3L syringe to check for [blank_start]leaks[blank_end] Volume should be checked at low, med and high [blank_start]flows[blank_end] to assure linerity Rotameter is a good device for [blank_start]reproducible[blank_end] low flows Sine-Wave [blank_start]pump[blank_end]: Biphasic, simulates flows and volumes Automatic Syringe - [blank_start]Computer[blank_end] Controlled motor syringe Explosive [blank_start]decompression[blank_end] device - simulates FVC Alinearity can happen: Contamination, bent vanes, moisture, debris Once volume displacement spirometer is caled it will retain linearity until it develops a [blank_start]leak[blank_end]