IOS articles 2010

here is a new list of articles that prove IOS is better than spirometry alone.

IOS spirometer connects to Vmax PFT

The IOS spirometer easily connects to the Vmax Encore PFT instrument from CareFusion, allowing it to share its database with Vmax. This is absolutely great for trending purposes as well as for getting better information for your patient or subject. The Vmax Encore PFT also has a new web page, with lots more interesting information on it.

www.carefusion.com/vmaxpft

Varying respiratory rate and IOS

Researchers from NYU / Bellevue hospitals in NYC found that elevated levels of breathing did, in fact, alter the IOS values and doctors and technicians must pay careful attention to this when looking at their data.

COPD. 2009 Jun;6(3):162-70. Distal airway function assessed by oscillometry at varying respiratory rate: comparison with dynamic compliance. Oppenheimer BW, Goldring RM, Berger KI. Division of Pulmonary and Critical Care Medicine, Department of Medicine, New York University School of Medicine/Bellevue Medical Center, New York, NY, USA. beno.oppenheimer@nyumc.org Elevated respiratory rate influences oscillometric parameters and must be considered when interpreting oscillometric data. IOS provides a non-invasive tool for assessment of distal airway function when spirometry is normal, which can be applied to various clinical settings including early diagnosis of COPD (GOLD stage 0), asthma in clinical remission and occupational/ environmental irritant exposure.

PMID: 19811371 [PubMed - in process]

More IOS Reactance

AX, or the area of reactance, is the area from X5 to Fres to 0.0

Fres, or resonant frequency

In many disease states that affect lung “stiffness” or resistance, the reactance worsens. Graphically you will see the X5 become more negative.

Both AX and Fres tend to increase in disease and decrease with bronchodilator response

IOS Reactance = Elastic Qualities of the Lung

In IOS, the elastic properties of the lung periphery are looked at in terms of Capacitance.

Capacitance can be defined as the ability to store energy.

Reactance (X) is measured and reported across the same frequencies as resistance (5-30Hz).

X5 = Lung reactance at 5Hz

Elasticity of lung & thorax

Dimensions of ventilated airways

Indirect indication of peripheral airway

obstruction

IOS Resistance Components

Airway Resistance (R) is both measured and reported in multiple frequencies.

The x-axis shows the different frequencies, with 5-20 being the most relevant for the airway.

Resistance at 20Hz:
Central Resistance (Rc)

Resistance at 5 Hz:

Total Resistance (Rc +Rp)

R (5Hz)- R(20Hz):

Peripheral resistance

When FEV1 fails to improve!

Forced oscillation using impulse oscillometry provides objective responses to corticosteroids in asthmatic patients when FEV1 fails to improve. Conclusions: As forced oscillation technique is automatic and can measure multiple breaths over long periods, it is suitable for monitoring expiratory flow limitation continuously and identifying patients’ breathing close to the onset of expiratory flow limitation, where intermittent sampling may be unrepresentative.

Dellacà RL, Duffy N, Pompilio PP, Aliverti A, Koulouris NG, Pedotti A, Calverley PM. E Resp J. 2007 Feb;29(2):363-74. Dipartimento di Bioingegneria, Politecnico di Milano University, Milan, Italy.

INCREASE PATIENT COMPLIANCE TO TESTING

Testing patients using the impulse technology requires only quiet breathing and not the maximal forced maneuvers that often result in patients quitting in the middle of the test. Data is only useful if it truly represents the patient’s best efforts, and IOS helps achieve that.

✔ QUIET BREATHING

✔ NO FORCED MANEUVERS

✔ INCREASES PATIENT COMPLIANCE

IOS: NORMAL PATIENT VS COPD PATIENT

NORMAL: The top graph depicts the results from a subject with normal lungs. It shows no frequency dependence of resistance, and both R5 and R20 follow the predicted line (dashed line) and are smaller than the upper limit of normal (indicated by the lightly shaded area).

COPD Patient: The bottom graph is representative of a COPD patient, showing a frequency dependence of resistance where R5>R20.