Related Experiment Video
Updated: May 21, 2026
Monitoring Lung Function with Electrical Impedance Tomography in the Intensive Care Unit
Published on: September 6, 2024
Comparison of automated and static pulse respiratory mechanics during supported ventilation
Alpesh R Patel1, Susan Taylor, Andrew D Bersten
1Intensive and Critical Care Unit, Flinders Medical Centre, Adelaide, SA, Australia. alpesh.patel@health.sa.gov.au
Objective:
To compare respiratory mechanics estimated by the (pulse) technique in spontaneously breathing patients during proportional assist ventilation (PAV) with load-adjustable gain factor (PAV+) mode with those measured using the flow-interruption technique during controlled ventilation.
Design, Participants And Setting:
Observational study of 21 haemodynamically stable post-cardiac surgery patients with routine weaning from mechanical ventilation (Puritan-Bennett 840 ventilator) in the intensive care unit of a tertiary hospital.
Main Outcome Measures:
Bland-Altman and linear correlation of respiratory system compliance and inspiratory resistance estimated during PAV+ (C(pulse) and R(pulse)) with that measured during controlled mechanical ventilation (C(int) and Rint).
Results:
C(pulse) overestimated C(int) (67.4 [SD, 27.7] v 51.6 [SD, 9.7] mL/cmH(2)O; P = 0.02), although the correlation between C(int) and C(pulse) was strong. Using the Bland-Altman method, the bias and limits of agreement were outside a clinically useful range. R(pulse) underestimated Rint (9.3 [SD, 3.0] v 11.5 [SD, 3.0] cmH(2)O/L/s; P = 0.02), with a weak positive correlation. Although the bias calculated by the Bland-Altman method was small, the limits of agreement were too large to be clinically useful.
Conclusion:
Based on these data, respiratory mechanics estimated from the (pulse) technique are too inaccurate to be clinically useful.
Related Concept Videos
01:23Mechanical Ventilation II: Invasive Ventilation
Negative-Pressure Ventilators
Negative-pressure ventilators create a vacuum around the chest or body to draw air into the lungs, simulating breathing. This method does not require an...
01:29Mechanical Ventilation I: Indication and Settings
01:29Assessment of Ventilation II: Respiratory Depth and Rhythm
Respiratory depth measures the volume of air inhaled or exhaled during a breath. It can vary from shallow to deep and typically remains consistent when a person is at rest or asleep. Occasionally, individuals will automatically inhale deeply, known as sighing, which inflates the lungs with more air than normal breathing.
To assess respiratory depth, observe the degree of chest excursion or movement:
01:14Ventilatory Modes
There are three ventilatory modes: full support, partial support, and spontaneous. These are described below.
Full Support Modes
Full support modes include controlled mechanical ventilation, continuous mandatory...
01:20Assessment of Ventilation I: Respiratory Rate
A Ventilation assessment is critical for monitoring a patient's health status. Respiration, one of the most accessible vital signs, provides insights into the function of numerous body systems and can indicate serious health issues, such as brainstem injuries from head trauma.
Critical Guidelines for Assessing Ventilation:
01:23Mechanical Ventilation III: Noninvasive Ventilation
Noninvasive Positive-Pressure Ventilation (NIPPV)