Figure 2.

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.