Effects of high-flow nasal cannula and non-invasive ventilation on inspiratory effort in hypercapnic patients with chronic obstructive pulmonary disease: a preliminary study

Annals of Intensive Care

Table 2 Simplified esophageal pressure–time product, respiratory variables, and hemodynamic variables during non-invasive ventilation and high-flow nasal cannula at different flow rates

Variables	NIV	HFNC-10	HFNC-20	HFNC-30	HFNC-40	HFNC-50	p
sPTP_es per breath (cmH₂O × s)	9 ± 4	11 ± 5	11 ± 6	10 ± 6	10 ± 5	10 ± 4	0.090
sPTP_es per minute (cmH₂O × s × min⁻¹)	183 ± 84	220 ± 100	211 ± 90	187 ± 84,*	189 ± 87	201 ± 86	< 0.001
RR (breaths/min)	25 [20–28]	24 [20–29]	23 [18–28]	21 [18–27]*	21 [18–27]^*	21 [18–26]^*	0.003
SpO₂ (%)	96 ± 2	95 ± 3	96 ± 3*	97 ± 3,*	97 ± 2,*	98 ± 2,*, ^γ	0.028
PtcCO₂ (mmHg)	42 ± 7	41 ± 7	41 ± 8	41 ± 7	41 ± 7	41 ± 7	0.335
MAP (mmHg)	99 ± 22	94 ± 15	92 ± 9	91 ± 12	89 ± 12	91 ± 14	0.179
HR (beats/min)	96 ± 16	97 ± 15	94 ± 13	93 ± 14	94 ± 16	95 ± 17	0.174
Oxygen flow (L/min) or Set FiO₂	4 [3–5]	0.35 [0.30–0.40]	0.35 [0.30–0.40]	0.35 [0.30–0.40]	0.35 [0.30–0.40]	0.35 [0.30–0.40]	–

Continuous variables were presented as mean ± SD or median [interquartile range] and categorical variables were presented as absolute value (%)
HFNC high-flow nasal cannula, HR heart rate, MAP mean arterial pressure, NIV non-invasive ventilation, sPTP_es, simplified esophageal pressure–time product, PtcCO₂, transcutaneous carbon dioxide pressure, RR respiratory rate, SpO₂, oxygen saturation
* Indicates p < 0.05 compared with HNFC-10, ** Indicates p < 0.05 compared with HFNC-20, ^γIndicates p < 0.05 compared with NIV