Figure 2
From: Automatic detection of patient-ventilator asynchrony by spectral analysis of airway flow
Airway flow signals and their corresponding frequency spectra. Frequencies shown as cycles per minute (cpm). H1 denotes the first harmonic peak amplitude and DC is the amplitude of the zero frequency component. Panel A illustrates a condition of patient-ventilator synchrony in which the spectral pattern is characterized by sharp peaks located at multiples of the respiratory rate. Panel B shows double triggering asynchrony during inspiration. Compared to that of Patient A, the frequency spectrum of Patient B has lost much of its initial organization. Panel C displays ineffective triggering asynchrony during expiration. The corresponding frequency spectrum also shows loss of organization and diminished H1 amplitude; cpm, cycles per minute; DC, zero frequency amplitude; H1, first harmonic peak amplitude; L/minute, liters per minute; s, seconds.