Clinical review: Intra-abdominal hypertension: does it influence the physiology of prone ventilation?

Table 2 Prone ventilation in relation to intra-abdominal pressure and obesity

				Intra-abdominal pressure
Study	Patients	Abdominal unloading	BMI (mean)	Zero, prime^a	Mean supine (mmHg)	Mean prone (mmHg)	ARDS type^b	Comments or major conclusions
Pelosi and colleagues [37]	10^c	Yes	34.6	NA	NR	NR	NA	FRC increased 1 l, lung compliance increased 18 cmH₂O
Pelosi and colleagues [36]	10^d	Yes	NR	Symph., 100 ml	11.4	14.8 (P = NS)	12% EP	Decreased chest wall compliance. Oxygenation better
Hering and colleagues [38]	16	No	NR	Symph., 250 ml	12	15 (P < 0.05)	21% EP	Renal function not impaired
Kiefer and colleagues [43]	25	Not described	NR	NR^e	10	11 (P = NS)	NR	Gastric tonometry decrements common
				NA
Hering and colleagues [39]	12	No	26	Symph., 250 ml	10	13 (P < 0.05)	34% EP	Splanchnic perfusion OK
Matejovic and colleagues [41]	11	No	NR	Axillary, 50 ml	10	11 (P = NS)	18% EP	Splanchnic perfusion OK
Michelet and colleagues [40]^f	20	No	NR	Symph., 100 ml	Approx. 6 (foam)	Approx. 12.5 (P < 0.01)	10% EP	No BMI or IAP data reported
					Approx. 8 (air)	Approx. 11 (P < 0.05)
Chiumello and colleagues [44]	11	Random	23.1	Symph., 100 ml	12	14.5 (suspended)	27% EP	Suspension not required
					14.5 (not)
Fletcher [42]	10	No	NR	Axillary, 50 ml	14.5	8.4 to 11.4^g (P = 0.0002)	100% DP	Proning does not increase IAP

ARDS, acute respiratory distress syndrome; axillary, mid-axillary line; BMI, body mass index; DP, direct pulmonary; EP, extrapulmonary; FRC, forced residual capacity; IAP, intra-abdominal pressure; NA, not applicable; NR, not reported; symph., pubic symphysis. ^aZero, reference point for IAP measurement; prime, priming volume for IAP measurement if intermittent bladder pressure measurement used. ^bAcute respiratory distress syndrome with best classification from reported data. ^cNo IAP measurements. ^dSixteen patients were in the main study but only 10 had IAP measured. ^eNo numerical IAP data reported only graphical results presented in this comparison of air-cushioned mattresses versus foam mattresses. ^fGastric pressure measurements. ^gTime series regression analysis of hourly IAP measurements.

ISSN: 1364-8535