Expiratory automatic endotracheal tube compensation reduces dynamic hyperinflation in a physical lung model

Haberthür, Christoph; Mehlig, Annekathrin; Stover, John F; Schumann, Stefan; Möller, Knut; Priebe, Hans-Joachim; Guttmann, Josef

doi:10.1186/cc7693

Critical Care

Table 1 Peak expiratory flow, intrinsic PEEP and trapped volume

From: Expiratory automatic endotracheal tube compensation reduces dynamic hyperinflation in a physical lung model

RR (l/minute)	Without ETT			Compensated ETT			Uncompensated ETT
	${\dot{V}}_{e x . \max}$ (l/second)	Intrinsic PEEP (cmH₂O)	V_trapped.dyn (ml)	${\dot{V}}_{e x . \max}$ (l/second)	Intrinsic PEEP (cmH₂O)	V_trapped.dyn (ml)	${\dot{V}}_{e x . \max}$ (l/second)	Intrinsic PEEP (cmH₂O)	V_trapped.dyn (ml)
Inspiratory pressure of 3.0 cmH₂O
15	0.75 ± 0.00	0.15 ± 0.02	4 ± 2	0.96 ± 0.02	0.15 ± 0.03	-31 ± 3	0.37 ± 0.02	0.79 ± 0.08	58 ± 8
20	0.74 ± 0.02	0.16 ± 0.01	12 ± 4	0.92 ± 0.01	0.15 ± 0.01	-12 ± 5	0.36 ± 0.02	0.88 ± 0.06	58 ± 9
25	0.70 ± 0.01	0.21 ± 0.04	23 ± 2	0.85 ± 0.01	0.29 ± 0.03	18 ± 10	0.36 ± 0.01	0.82 ± 0.02	77 ± 6
30	0.69 ± 0.01	0.29 ± 0.02	36 ± 2	0.77 ± 0.01	0.32 ± 0.02	43 ± 5	0.34 ± 0.01	0.97 ± 0.03	109 ± 2
Inspiratory pressure of 4.5 cmH₂O
15	1.12 ± 0.01	0.18 ± 0.03	6 ± 1	1.17 ± 0.01	0.18 ± 0.01	-5 ± 30	0.48 ± 0.01	0.63 ± 0.02	54 ± 5
20	1.10 ± 0.01	0.22 ± 0.03	18 ± 6	1.13 ± 0.01	0.38 ± 0.00	37 ± 11	0.46 ± 0.01	0.93 ± 0.00	96 ± 2
25	1.08 ± 0.01	0.30 ± 0.02	34 ± 2	1.06 ± 0.01	0.42 ± 0.02	82 ± 2	0.45 ± 0.01	1.28 ± 0.02	160 ± 3
30	1.02 ± 0.01	0.49 ± 0.02	54 ± 4	0.97 ± 0.02	0.50 ± 0.02	124 ± 3	0.43 ± 0.01	1.48 ± 0.01	240 ± 3
Inspiratory pressure of 6.0 cmH₂O
15	1.50 ± 0.04	0.16 ± 0.02	8 ± 2	1.22 ± 0.01	0.19 ± 0.01	15 ± 6	0.57 ± 0.01	0.91 ± 0.02	60 ± 5
20	1.45 ± 0.01	0.21 ± 0.02	25 ± 2	1.20 ± 0.01	0.38 ± 0.01	84 ± 2	0.55 ± 0.01	1.38 ± 0.02	161 ± 2
25	1.43 ± 0.02	0.40 ± 0.01	46 ± 5	1.18 ± 0.01	0.52 ± 0.01	147 ± 3	0.52 ± 0.01	1.71 ± 0.01	246 ± 1
30	1.39 ± 0.02	0.63 ± 0.01	72 ± 2	1.13 ± 0.01	0.56 ± 0.02	204 ± 4	0.50 ± 0.01	2.03 ± 0.01	310 ± 1

Shown are the peak expiratory flow, intrinsic PEEP and trapped volume at a test lung compliance of 113 ml/cmH₂O and an ETT of 7.0 mm ID. Values are expressed as mean ± standard deviation. Respective differences between uncompensated and compensated ETT are significantly different (P < 0.025). ATC, automatic tube compensation; ETT, endotracheal tube; ID, inner diameter; PEEP, positive end-expiratory pressure; RR, respiratory rate; ${\dot{V}}_{e x . \max}$ , peak expiratory flow; V_trapped.dyn, trapped lung volume (difference between calculated [ideal] and measured inspiratory lung volume).

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ISSN: 1364-8535

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