Fig. 6. Effects of ventilator mode and level of assistance on the coefficient of variation (CV) and autocorrelation analysis of diaphragm electrical activity (EAdi). The CVs for peak (CV^EAdipeak), rate of rise (CV^{EAdipeak/EAditp}), and integrated EAdi per breath (CV^∫EAdi) are similar between pressure support ventilation (PSV) and the lowest level of neurally adjusted ventilatory assist (NAVA). Increasing NAVA gain had a limited effect on these indices, values differing only at the highest NAVA setting. Values of lag, that is, the number of breaths among which a significant correlation is found by autocorrelation analysis, for peak (lag^EAdipeak), rate of rise (lag^{EAdipeak/EAditp}), and integrated Edi per breath (lag^∫EAdi) are not significantly altered by the change in ventilator mode or the subsequent increases in NAVA gain. NAVA^{1, 2, 3, 4}= neurally adjusted ventilatory assist with a gain of 1, 2, 3, 4 cm H²O/μV EAdi, respectively. Data are means ± SEM; *P < 0.05.