Continuous external negative pressure improves oxygenation and respiratory mechanics in Experimental Lung Injury in Pigs – A pilot proof-of-concept trial

Scharffenberg, Martin; Wittenstein, Jakob; Herzog, Moritz; Tauer, Sebastian; Vivona, Luigi; Theilen, Raphael; Bluth, Thomas; Kiss, Thomas; Koch, Thea; Fiorentino, Giuseppe; de Abreu, Marcelo Gama; Huhle, Robert

doi:10.1186/s40635-020-00315-1

Intensive Care Medicine Experimental

Table 2 Ventilator settings, airway pressure variables and mechanical power

From: Continuous external negative pressure improves oxygenation and respiratory mechanics in Experimental Lung Injury in Pigs – A pilot proof-of-concept trial

Parameter	PEEP [cmH₂O]	Position	CENP [cmH₂O]					ANOVA (P-values)
			0	-10	-20	-30	-40	Position	CENP	PEEP	Mixed
Tidal volume V_T (mL/kg)								0.801	0.081	0.694	0.997
	0	abdomen	5.77±0.4	5.71±0.4	5.67±0.3	5.65±0.4	5.76±0.4	0.070	0.708		0.620
	0	thorax	5.79±0.5	5.71±0.4	5.83±0.5	5.83±0.5	5.81±0.5
	7	abdomen	5.8±0.5	5.71±0.4	5.78±0.4	5.89±0.4	5.83±0.4	0.109	0.694		0.723
	7	thorax	5.78±0.4	5.58±0.4	5.72±0.3	5.67±0.4	5.82±0.5
	15	abdomen	5.78±0.4	5.67±0.3	5.72±0.4	5.72±0.4	5.8±0.4	0.713	0.689		0.922
	15	thorax	5.73±0.4	5.65±0.5	5.77±0.4	5.74±0.5	5.72±0.5
Respiratory rate RR (min^-1)								0.540	0.088	0.005	0.403
	0	abdomen	21±7.6	21.4±8.5	21.2±7.6	20.9±7.6	21±7.8	0.064	0.933		0.978
	0	thorax	20.6±7.7	21±9.1	20.5±8.4	20.5±8	20.1±7.9
	7	abdomen	17.3±4	20.8±9.2	20.3±7.4	20.1±7.1	20.9±8.2	0.639	0.166	⁰	0.536
	7	thorax	19.6±7.2	22.2±8.9	19.8±7.4	19.9±7.3	19.6±7.7
	15	abdomen	19.8±7	20.1±7.4	19.9±7.2	19.9±7	19.8±7.5	0.110	0.956	^0,7	0.983
	15	thorax	19.5±7.1	19.9±7.8	19.5±7.5	19.4±7.1	19.6±7.7
Minute volume ventilation MV (L)								0.030	0.735	<0.001	0.517
	0	abdomen	6.8±2.1	6.8±2.1	6.7±2.0	6.8±2100	6.7±1.9	0.045	0.968		0.997
	0	thorax	6.6±2.1	6.6±2.1	6.6±2.1	6.6±2100	6.4±2.0
	7	abdomen	5.6±1.2	6.6±2.2	6.6±2.0	6.6±2.0	6.6±2.1	0.565	0.051	⁰	0.315
	7	thorax	6.3±1.7	6.2±1.7	6.3±1.7	6.2±1.7	6.4±1.7
	15	abdomen	6.4±2.2	6.4±2.2	6.4±2.1	6.4±2.1	6.4±2.1	0.001	0.997	^0,7	0.996
	15	thorax	6.2±1.8	6.2±1.7	6.2±1.8	6.1±1.7	6.2±1.7
Mean airway pressure mean P_AW (cmH₂O)								0.817	0.025	<0.001	0.009
	0	abdomen	11.9±2	11.3±2.1	10.7±2	10.7±1.7	9.84±2.1	0.534	<0.001		0.780
		thorax	11.6±1.7	11.4±1.8	11±1.9	10.7±1.9	10.2±1.8
					⁰	⁰	^0,10,20
	7	abdomen	15.2±1	15.3±1.7	14.9±1.6	14.8±1.6	14.8±1.5	0.471	0.550	⁰	0.552
		thorax	15.5±1.4	14.8±1.2	14.8±1.3	14.6±1.3	14.6±1.4
	15	abdomen	21.4±1.4	21.5±1.5	21.7±1.5	22±1.5	22±1.4	0.696	0.792	^0,7	0.983
		thorax	21.8±1.6	21.7±1.4	21.8±1.4	21.9±1.4	21.9±1.4
Peak airway pressure peak P_AW [cmH₂O]								0.821	<0.001	<0.001	<0.001
	0	abdomen	29.5±3.6	28.4±3.7	26.8±3.7	26.8±2.7	24.7±3.9	0.214	<0.001		0.766
		thorax	29.3±3.5	28.7±3.5	27.7±3.7	26.9±3.9	25.8±3.9
					⁰	^0,10	^0,10,20
	7	abdomen	28.5±2.1	28±2.5	27.3±2.5	27.1±2.4	26.9±2	0.572	0.023		0.797
		thorax	28.9±2.8	27.5±2.2	27.3±2.5	26.9±2.5	26.6±2.9
					⁰	⁰	⁰
	15	abdomen	31.8±2	31.9±2.1	32.7±2.1	33.3±2.1	33.3±1.9	0.636	0.098	^0,7	0.873
		thorax	32.2±2.1	32±2.1	32.4±2.1	32.8±2.3	32.7±2.3
Airway driving pressure ∆P_AW (cmH₂O)								0.045	<0.001	<0.001	<0.001
	0	abdomen	24.5±3.2	23.8±3.3	22.3±3.4	22.5±2.8	20.4±3.6	0.088	<0.001		0.635
		thorax	24.3±3.5	24.4±3.4	23.3±3.9	22.7±4	21.7±4
					⁰	⁰	^0,10,20
	7	abdomen	17.8±2.4	17±2.5	16.2±2.2	16±1.9	15.5±1.9	0.227	<0.001	⁰	0.761
		thorax	18.2±2.8	16.8±2.1	16.7±2.5	16.2±2.7	16.2±3.2
				⁰	⁰	⁰	^0,10
	15	abdomen	12.7±1.4	13±1.3	13.6±1.4	14.4±1.1	14.2±1.1	0.288	0.001	^0,7	0.425
		thorax	13.6±2.4	13.5±2.5	13.7±2.3	14.1±2.8	14.1±2.7
						⁰
Positive end-expiratory pressure PEEP (cmH₂O)								0.411	0.894	<0.001	0.936
	0	abdomen	0.313±1.2	0.209±1.2	0.172±1.2	0.341±1.4	0.208±1.2	0.177	0.885		0.947
		thorax	0.146±0.67	0.129±0.68	0.11±0.67	0.104±0.69	0.17±0.66
	7	abdomen	6.62±0.66	7.05±1.5	7.18±1.4	7.23±1.3	7.3±1.2	0.343	0.015	⁰	0.399
		thorax	6.86±1	7.03±0.85	6.88±0.99	6.96±1	7.19±0.93
							⁰
	15	abdomen	15.3±1.3	15.4±1.3	15.4±1.3	15.3±1.3	15.4±1.3	0.908	1.000	^0,7	1.000
		thorax	15.4±1.7	15.3±1.5	15.3±1.4	15.3±1.4	15.3±1.3
Mechanical power MP (J/min)								0.687	0.009	<0.001	0.010
	0	abdomen	12.7±4.8	12±4.4	11±3.9	10.5±3.5	9.9±3.4	0.329	<0.001		0.805
		thorax	12.4±4.8	12±4.2	11.6±4.2	11.2±3.9	10.3±3.2
						⁰	^0,10
	7	abdomen	7.4±1.5	8.08±2.9	7.36±1.8	7.27±1.7	7.36±2	0.957	0.448	⁰	0.587
		thorax	8.1±2.2	7.81±1.9	7.34±1.9	7.04±1.8	7.12±2
	15	abdomen	5.97±2.4	6.02±2.5	6.17±2.5	6.38±2.7	6.41±2.6	0.004	0.663	^0,7	0.947
		thorax	5.69±1.4	5.6±1.3	5.77±1.4	5.75±1.2	5.76±1.3
Index of over-distension %E₂ (%)								0.787	0.262	<0.001	0.535
	0	abdomen	-28.5±5.3	-27.9±5.1	-27.5±3.1	-25.4±2.4	-24.1±2.9	<0.001	0.025		0.565
		thorax	-30.7±7.8	-30.4±6.9	-30.7±5.5	-30.3±4.5	-29.2±4.7
							*
	7	abdomen	0.00224±7	1.69±7.8	2.49±8.7	7.24±10	5.78±8.3	0.011	0.404	⁰	0.745
		thorax	-8.1±12	-5.78±12	-1.84±13	4.29±13	4.58±19
				*
	15	abdomen	49.8±16	42.4±17	44.3±14	42.8±13	43.5±14	0.002	0.632	^0,7	0.505
		thorax	48.6±23	52±23	53.2±22	53.8±27	51.5±26
Resistance R (cmH₂O·s/l)								0.674	<0.001	<0.001	0.015
	0	abdomen	0.244±0.043	0.235±0.043	0.218±0.034	0.209±0.027	0.191±0.033	0.014	<0.001		0.759
		thorax	0.247±0.043	0.242±0.037	0.234±0.034	0.224±0.028	0.215±0.027
						⁰	^0,10
	7	abdomen	0.177±0.028	0.171±0.027	0.158±0.027	0.157±0.03	0.154±0.026	0.546	0.005	⁰	0.948
		thorax	0.172±0.015	0.167±0.014	0.161±0.018	0.154±0.019	0.153±0.02
						⁰	^0,10
	15	abdomen	0.138±0.037	0.136±0.032	0.135±0.032	0.133±0.024	0.138±0.021	<0.001	0.956	^0,7	0.996
		thorax	0.121±0.019	0.121±0.023	0.122±0.02	0.12±0.023	0.122±0.026

Values are mean ± standard deviation. Linear-mixed effects, repeated-measures ANOVA with factors position (abdomen or thorax), PEEP and CENP were performed for each parameter (1^st line) over all values and for each PEEP-step (1^st line of each PEEP step). Post hoc comparison was done according to Sidak after significant effects for CENP (0, 10, 20 and 30 indicate if the value at respective CENP was different compared to CENP 0, 10, 20 and 30 cmH₂O, respectively) or PEEP (0 or 7 in PEEP effects column indicate the significant difference between the respective PEEP row with PEEP level indicated in the number, e.g. 0 or 7) or Position (* position effects at the respective CENP). Significance was accepted for P < 0.05
CENP continuous external negative pressure, PEEP positive end-expiratory pressure

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