Effects of changes in trunk inclination on ventilatory efficiency in ARDS patients: quasi-experimental study

Benites, Martín H.; Torres, David; Poblete, Fabian; Labbe, Francisco; Bachmann, María C.; Regueira, Tomas E.; Soto, Leonardo; Ferre, Andrés; Dreyse, Jorge; Retamal, Jaime

doi:10.1186/s40635-023-00550-2

Intensive Care Medicine Experimental

Table 2 Effect of trunk inclination on ventilatory parameters, gas exchange, lung impedance, and hemodynamics

From: Effects of changes in trunk inclination on ventilatory efficiency in ARDS patients: quasi-experimental study

	STEP I—45° (n = 22)	STEP II—10° (n = 22)	STEP III—45° (n = 22)	P values
Respiratory mechanics
Tidal volume (mL)	371 ± 76	433 ± 84 ^a	365 ± 78^b	p < 0.001
Minute ventilation (mL/kg/min)	120 [112–150]	143 [128–168]^a	121 [109–149]^b	p < 0.001
Driving pressure (cm/H₂O)	12 [10–14]	12 [10–14]	12 [10–14]	–
PEEP (cm/H₂O)	9 [7–11]	9 [7–11]	9 [7–11]	–
Total PEEP (cm/H₂O)	10 [8–12]	10 [8–12]	10 [8–12]	–
Respiratory rate (bpm)	20 [18–24]	20 [18–24]	20 [18–24]	–
Ventilatory ratio (VR)	1.66 ± 0.39	1.43 ± 0.31	1.6 ± 0.39	p = 0.107
Arterial blood gases
Arterial pH	7.39 ± 0,05	7.45 ± 0,05 ^a	7.39 ± 0.06 ^b	p = 0.003
PaCO₂ (mmHg)	43 ± 5	36 ± 4 ^a	42 ± 5 ^b	p < 0.001
PaO₂/FiO₂ ratio (mmHg)	189 ± 33	196 ± 34	191 ± 28	p = 0.735
Volumetric capnography
VD_Bohr/V_T	0.49 ± 0.07	0.41 ± 0.06^a	0.48 ± 0.07^b	p < 0.001
Enghoff's index of gas exchange	0.56 ± 0.08	0.48 ± 0.08^a	0.54 ± 0.08	p = 0.006
V̇CO₂ (ml/min)	191 ± 34	227 ± 38^a	212 ± 44	p = 0.013
Alveolar ventilation (mL/kg/min)	74 ± 16	99 ± 21^a	80 ± 17^b	p < 0.001
VD_aw/V_T	0.36 ± 0.06	0.29 ± 0.06^a	0.35 ± 0.06^b	p = 0.002
VD_alv/V_Talv	0.19 ± 0.04	0.16 ± 0.03	0.18 ± 0.04	p = 0.066
VT_alv/V_T	0.51 [0.48–0.54]	0.58 [0.56–0.63]^a	0.52[0.49–0.56]^b	p < 0.001
SnIII (L⁻¹)	1.45 [0.75–2.07]	0.58 [0.49–1.03]^a	1.37 [0.73–1.69]^b	p < 0.001
E_TCO₂ (mmHg)	40 ± 4	34 ± 4 ^a	40 ± 5 ^b	p < 0.001
Impedance electric tomography
Impedance ratio (AU)	1.3 [0.8–1.8]	0.9 [0.5–1.3]^a	1.36 [1.1–1.8]^b	p < 0.001
Global Tidal variation (AU)	794 [444–1226]	841 [606–1333]	789 [442–1270]	p = 0.186
Global EELI (AU)	149 [90–367]	130 [91–256]	189 [90–319]	p = 0.421
Global Inhomogeneity index (AU)	1.3 [1.1–1.5]	1.2 [1.1–1,4]	1.15 [1.1–1.4]	p = 0.700
Basic hemodynamic
Pulse pressure variation (%)	6 [5–7]	5.5 [5, 6]	6 [5–7]	p = 0.101
Heart rate (bpm)	72 ± 17	68 ± 16	69 ± 16	p = 0.353
Mean arterial pressure (mmHg)	76 ± 7	78 ± 8	77 ± 9	p = 0.133

Bpm breaths/min; PaO₂/FiO₂ partial pressure of arterial oxygen over fraction of inspired oxygen; VD_alv/VT_alv alveolar dead space to alveolar expiratory tidal volume ratio, VT_alv/V_T alveolar ventilation fraction; SnIII Capnogram at phase III normalized by the fraction of expired CO₂; E_TCO₂ end-tidal partial pressure of CO₂; AU arbitrary units
Values are presented as the mean ± standard deviation (SD) or median and interquartile range [IQR]
ANOVA for repeated measures and Friedman’s test were performed to compare multiple variables. Bonferroni correction and Dunn’s post hoc tests were used
^ap < 0.05 s step (10°) vs. first step (45°)
^bp < 0.05 third step (45°) vs. second step (10°)
^cp < 0.05 third step (45°) vs. first step (45°). No patient showed significant differences between the first and third steps

Back to article page