Which values in the flow volume loop indicate asthma?

FEV1= forced expiratory volume in 1 second; FVC = forced vital capacity; TLC = total lung capacity. Improvement of FEV1 and FEV1/FVC by ≥ 12% or 200 mL with the administration of a bronchodilator confirms the diagnosis of asthma or airway hyperresponsiveness.

What does a flow volume loop indicate?

Flow-volume loops are produced by asking the patient to breath out then in as forcefully as possible, and may reveal a characteristic pattern suggestive of restrictive, obstructive or other pulmonary disease.

What are the 4 phases of an acceptable flow volume loop?

FVC = forced vital capacity; MEF = maximal expiratory flow; MIF = maximal inspiratory flow; PEF = peak expiratory flow; RV = residual volume; TLC = total lung capacity. Flow-volume loops require that absolute lung volumes be measured.

Which of the following are features of a flow volume loop in a person with COPD?

Characteristic features of obstructive lung disease in the flow-volume loop include the following:

• Low peak inspiratory flow.
• Low peak expiratory flow.
• Failure of the expiratory flow curve to reach zero (an “open loop”)
• A “scooped out” expiratory flow pattern.

Why is flow volume loop important?

The flow-volume loop is a plot of inspiratory and expiratory flow (on the Y-axis) against volume (on the X-axis) during the performance of maximally forced inspiratory and expiratory maneuvers. Changes in the contour of the loop can aid in the diagnosis and localization of airway obstruction [1].

What is a normal flow volume loop?

NORMAL FLOW-VOLUME LOOP. The flow-volume loop is a plot of inspiratory and expiratory flow (on the Y-axis) against volume (on the X-axis) during the performance of maximally forced inspiratory and expiratory maneuvers (figure 1).

What is the importance of flow volume loops?

Upper airway obstruction is an important but often unrecognised cause of dyspnoea and ventilatory failure. Flow volume loop remains the most sensitive method to detect upper airway obstruction.

What is predicted FVC?

The forced vital capacity (FVC) measurement shows the amount of air a person can forcefully and quickly exhale after taking a deep breath. In general, doctors compare your FVC measurement with the predicted FVC based on your age, height and weight.

How do you do a flow volume loop?

breathing across a pneumotachograph subjects inhale to TLC -> FEC manoeuvre -> rapidly inhale back to TLC. airflow from TLC is maximal at the beginning of forced exhalation where: elastic traction of alveolar septa on airway is greatest.

What are the signs of airway obstruction in flow-volume loops?

Signs of airway obstruction in flow-volume loops: Flow-volume loops typically become more concave both with increasing age and with an increase in the severity of airway obstruction. This concavity has been variously termed “scooping” or “coving”.

What are the characteristics of the flow-volume loop?

The flow-volume loop will have characteristics of both syndromes. A typical shape of the flow-volume loop is seen in cases of obstruction of the large airways. Three different shapes of flow-volume loops can be distinguished. Typically the expiratory part of the F/V-loop is normal: the obstruction is pushed outwards by the force of the expiration.

When does a flow-volume loop appear in spirometry?

This type of flow-volume loop is typically found in younger subjects and more often in females than in males. Longitudinal studies have shown that this feature often disappears with increasing age even when spirometry results remain normal.

Which is an example of an intrathoracic flow-volume loop?

During expiration the tumor is pushed into the trachea with partial obstruction and flattening of the expiratory part of the F/V loop. This can be both intrathoracic as extrathoracic. The flow-volume loop is typically flattened during inspiration and expiration. Examples are tracheal stenosis caused by intubation and a circular tracheal tumor.