An efficient, automated assessment tool

Traditional respiratory mechanics maneuvers to assess lung health and determine readiness for weaning require disconnecting the ventilator circuit, potentially increasing the risk of circuit contamination.

The Puritan Bennett Respiratory Mechanics software offers an alternative to traditional maneuvers. Its maneuvers assess vital capacity, negative inspiratory force and respiratory drive (P0.1) without disconnecting the circuit or using outside equipment.

Clinicians can quickly assess patient respiratory therapy needs based on these measurements, while avoiding the probability of cross-contamination and risk of infection because there is no need to disconnect the breathing circuit during the automated measurements.



The Puritan Bennett Respiratory Mechanics software makes it easy to assess and rapidly make any necessary changes in a patient’s respiratory therapy. The software provides coached respiratory maneuvers such as negative inspiratory force (NIF) and vital capacity (VC). The Respiratory Mechanics software data, including occlusion pressure, can help clinicians determine if a patient is ready to be weaned.

The Respiratory Mechanics software calculates and displays clinical indicators that may be useful in assessing the patient’s current respiratory status. The calculations displayed are listed below.

Dynamic Compliance (CDYN) and Resistance Dynamics (RDYN)

Respiratory Mechanics software estimates the compliance and resistance of the patient’s lungs and chest wall. The measurement of CDYN and RDYN indicate the impedance characteristics of the lungs, chest wall and conducting airways. Changes in either of these values may reveal changes in the elastic properties of the lung and/or chest wall or in the ability of the conducting airways to accommodate a particular flow of gas. Dynamic compliance and dynamic resistance are calculated only for mandatory breaths.

Peak Expiratory Flow (PEF) Rate

Peak expiratory flow is the maximum flow rate observed during exhalation, excluding the first 100 ms of data. PEF can be used as an indicator of obstructed airways.

End Expiratory Flow (EEF) Rate

End expiratory flow is the rate of expiratory flow that occurs at the end of exhalation and can be used to determine whether expiratory time is adequate to prevent gas trapping and intrinsic PEEP. The end expiratory flow rate is calculated as the expiratory flow that occurs when flow integration terminates during exhalation or when a new breath is initiated.

Peak Spontaneous Flow (PSF) Rate

Peak spontaneous flow is the maximum inspiratory flow rate sampled during a spontaneous inspiration. It is a good predictor of impending air hunger and helps the clinician set peak flow or choose an optimum level of pressure support.



The Puritan Bennett Respiratory Mechanics software automatically calculates and displays the following performance indicators:

Monitored data maneuver, function, range, resolution and accuracy.

Negative inspiratory force (NIF)
Measures maximum inspiratory force against an occluded airway.
Range ≤ 0 cmH2O to ≥ -50 cmH2O
Resolution 0.1 cmH2O NIF > -10 cmH2O
  1 cmH2O for NIF ≤ -10 cmH2O
Occlusion pressure (P0.1)
Measures pressure generated after 100 ms of inspiration against an occluded airway
Range ≥20 to 0 cmH2O
Resolution 0.1 cmH2O for P0.1 > -10 cmH2O
  1 cmH2O for P0.1 ≤ -10 cmH2O
Vital capacity (VC)
Measures the maximum volume that can be exhaled after a maximum inhalation
Range 0 to 6,000 mL
Resolution 0.1 mL for 0 to 9.9 mL
  1 mL for values ≥ 10 mL
Peak Expiratory Flow (PEF) in L/min
The maximum flow rate observed during exhalation, excluding the first 100 msec
End Expiratory Flow (EEF) in L/min
The flow rate measured at the end of exhalation.
Dynamic compliance (CDYN) in mL/cm H2O
Dynamic resistance (RDYN) in cmH2O/L/s