Commonly applied positive end-expiratory pressures do not prevent functional residual capacity decline in the setting of intra-abdominal hypertension: a pig model

Table 2 Influence of positive end-expiratory pressure on respiratory and haemodynamic data at 18 mmHg intra-abdominal pressure

PEEP, cmH₂O	5	8	5 vs 8	12	5 vs 12	15	5 vs 15
FRC, L	0.9 (0.3) *	1.0 (0.3) *	0.034	1.0 (0.3) *	0.049	1.1 (0.3) *	< 0.001
PaO₂, mmHg	215 (32)	218 (20) *	NS	222 (23) *	NS	216 (26)	NS
pPaw, cmH₂O	29 (5) *	31 (5) *	< 0.001	34 (5) *	< 0.001	37 (5) *	< 0.001
mPaw, cmH₂O	12 (3) *	15 (3) *	< 0.001	18 (3) *	< 0.001	21 (4) *	< 0.001
C dyn, ml/cmH₂O	15 (4) *	15 (3) *	NS	16 (4) *	NS	16 (4) *	NS
CO, L/min	3.5 (0.9)	3.4 (0.7)	NS	3.4 (0.9)	NS	3.1 (0.8) *	NS
DO₂, ml/min	490 (130)	472 (91)	NS	472 (124) *	NS	428 (116) *	NS
SvO₂, %	61 (9)	61 (10)	NS	58 (11) *	NS	56 (14) *	NS
VO₂, ml/min	195 (64)	192 (50)	NS	202 (55)	NS	186 (47)	NS
MAP, mmHg	83 (12)	79 (11) *	NS	81 (16) *	NS	72 (13) *	< 0.001
APP, mmHg	65 (13)	62 (12)	NS	63 (18)	NS	56 (12)	0.013
CVP, mmHg	10 (3) *	11 (2) *	NS	13 (4) *	< 0.001	15 (1) *	< 0.001
PAOP, mmHg	7 (2)	9 (1) *	< 0.001	11 (2) *	< 0.001	12 (1) *	< 0.001
HR, beats/min	73 (16)	72 (14)	NS	74 (14)	NS	76 (14)	NS
SVR, dyn * s/cm⁵	1,643 (364)	1,600 (217) *	NS	1,580 (248)	NS	1,491 (275)	NS
SV, ml	52 (23)	49 (10) *	NS	47 (14) *	NS	42 (12) *	NS

APP, abdominal perfusion pressure; Cdyn, dynamic compliance; CO, cardiac output; CVP, central venous pressure; DO₂, oxygen delivery; FRC, functional residual capacity; HR, heart rate; MAP, mean arterial pressure; mPaw, mean airway pressure; PaO₂, arterial oxygen tension; PAOP, pulmonary artery occlusion pressure; PEEP, positive end-expiratory pressure; pPaw, peak airway pressure; SV, stroke volume; SvO₂, mixed venous oxygen saturation; SVR, systemic vascular resistance; VO₂, oxygen consumption. Mean (SD) are given. ANOVA and post hoc Student-Newman-Keuls were used for statistical testing. *, significant (P < 0.05) difference compared with baseline IAP. NS, not significant.

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