SVC: ERV have to vary less than ___ for __ breaths
100mls, 3 breaths
ATS FVL Acceptability Criteria
1) Good Start: get to peak w/in 120ms or don’t blow out more than 100mls or 5% of FVR prior to peak
2) End of Test: >/= to 6sec duration (adult), 3sec (children); plateau <0.025L for >/= to 1sec; expiratory time >/= 15sec
3) No Artifact: cough w/in 1sec, glottis closure, early termination, cut-off, leaks, obstructions, mouthpiece problems
ATS FVL Repeatability Criteria
- > /= 3 acceptable tests; continue until approx. 8 tests or patient unable to continue
- FVC w/in 150mls
- FEV1 w/in 150mls
- PEFR w/in 0.67L/sec (40L/min)
Utility of Inspiratory Curve FIF50
Info re. upper airway obstruction
- fixed obstruction: constant airflow limitation on insp + exp (eg. tumor, tracheal stenosis)
- variable extra thoracic obstruction: limitation on insp flow/flattened insp loop (eg. vocal chord dysfunction)
- variable intrathoracic obstruction: flattened exp limb (eg. malignancy, tracheomalacia)
Flow Impairment:
FEV1/FVC </= 70% (adult) 80% (peds)
FEV1
- normal >/= 70%
- mild obstruction >70%
- moderate obstruction 60-69%
- moderately severe 50-59%
- severe obstruction 35-49%
- very severe <35%
Volume Impairment
Evaluate FVC against the % predicted normal LLN (80-120); can’t diagnose restriction w/ spirometry alone (need TLC to confirm)
- mild restriction <LLN to 65%
- moderate restriction 64-50%
- severe restriction <49%
MVV Acceptability Criteria
- V/T continuous/rhythmic effort for >/= 12sec
- Volume ~50% of VC
- RR=90-110
- 2 acceptable maneuvers w/in 20%
how can you measure … volumes
dynamic: spirometer; respirometer
static: displacement
how can you measure … airflows
peak: peak flow meter
mid breath: computer and/or paper based measure
how can you measure … pressures
mouth: manometer
alveolar: manometer with NO airflow and/or esophageal manometer
LLN Definition
5% of the population with healthy lungs have lower values
LLN is ~80% of predicted for FEV1 and FVC; ~90% of predicted for FEV1/FVC ratio; ~60% predicted for FEF25-75%
VOPS
Ventilate
Obstruction
Protection
Secretions
Normal Values: MIPS & MEPS
MIP
- women: -50cmh2o
- men: -75cmh2o
MEP
- women: >80cmh2o
- men: >100cmh2o
Daily Calibration Spirometry for Accuracy
Volume: w/in 3% or +/- 0.05L from 0.5-8L
Flow: w/in 5% or 0.2 L/sec up to 14 sec
which equipment can measure flow in both directions
- Heated Wire / Thermal Flowmeter or Anemometer
- Pitot Tube
- Pressure Differentials (Variable Orifice, Fleish and Screen/Silverman)
which equipment can only measure unidirectional flow
- Electronic Rotating Vane
- Wright Respirometer
- Ultrasonic
which equipment is neg affected by turbulent flow
- Pressure Differential
- Pitot
- Heated Wire / Thermal Flowmeter or Anemometer
which equipment works with laminar or turbulent flow
- Electronic Rotating Vane
- Ultrasonic
which equipment has issues with high/low flow
- Wright Turbine issues at flows under 3lpm or over 300lpm
- Electronic Rotating Vane issues at low flows
- Variable Orifice Pressure Differential issues at very low & high flows
which equipment is affected by gas composition / temperature / humidity
- Wright Turbine
- Heated Wire / Thermal Flowmeter or Anemometer
- Pitot Tube
- Pressure Differential
which equipment is not affected by gas composition / temperature / humidity
- Electronic Rotating Vane
- Ultrasonic
which equipment meets ATS criteria
- Dry Rolling Seals
- Bellows Type
- Heated Wire / Thermal Flowmeter or Anemometer
- Pitot Tube
- Pressure Differential
which equipment does not meet ATS criteria
- Water Sealed
- Stead Wells
- Wright Turbine
- Electronic Rotating Vane
- Ultrasonic
