Fig. 1.

CIH increases apnoea index

Poincaré plots of breath-to-breath (BBn) and subsequent breath-to-breath (BBn + 1) interval of expiratory duration (T_e; a) and total breath duration (T_tot; b) for Sham+VEH, CIH+VEH, Sham+PREB and CIH+PREB. Group data for T_e short-term variability (SD1; c) and long-term variability (SD2; d) and T_tot SD1 (e) and SD2 (f) in Sham+VEH, CIH+VEH, Sham+PREB and CIH+PREB rats during normoxia. Representative respiratory flow traces (downward deflections represent inspiration) illustrating a spontaneous sigh followed by an apnoea (g), a spontaneous apnoea (h) and a spontaneous sigh (i). Group data of apnoea index (j) and sigh frequency (k). CIH, chronic intermittent hypoxia; PREB, prebiotic; VEH, vehicle. Groups (c-f, j, k) are expressed as box and whisker plots (median, IQR and minimum to maximum values); n = 11–12. Groups were statistically compared using two-way ANOVA, followed by Fisher's least significant difference (LSD) post hoc where appropriate, or non-parametric Kruskal-Wallis test, followed by Mann-Whitney U test, where appropriate. Apnoea index was significantly affected by CIH exposure (p = 0.026; Fig. 1j). Assessments of respiratory timing variability and frequency of sighs were not different between groups (p>0.05; Fig. 1a-f, 1k). # p = 0.008, CIH+PREB versus Sham+PREB.