Effect of abdominal distension on central and regional hemodynamics in neonatal lambs

Elevations of intraabdominal pressure (IAP) can occur during surgical repair of gastroschisis and omphalocele and lead to ischemia of abdominal organs. We examined the effect of elevated IAP on central hemodynamics and regional abdominal organ blood flow, measured by radiolabeled microspheres, in 11 pentobarbital-anesthe-tized neonatal lambs. Stepwise increases in IAP were obtained by inflating a large bag placed intraperitoneally with air to pressures of 15, 20, and 25 mm Hg. Measurements were made at 30 min of elevated IAP and 30 min after deflating the bag. Mean aortic pressure was not significantly altered at an IAP of 15 mm Hg (78 ± 4 mm Hg) (±SE) or 20 mm Hg (76 ± 4 mm Hg) compared to baseline (81 ± 4 mm Hg), but was decreased at the highest IAP (68 ± 5 mm Hg). Stepwise decreases in blood flow to all abdominal organs, except adrenal gland, occurred with elevated IAP, and blood flows to these organs (except spleen) returned to or above baseline on bag deflation. At IAP of 15, 20, and 25 mm Hg, cardiac output was reduced by 14, 21, and 35%, respectively. Similar percent reductions of renal blood flow occurred. However, regional gastrointestinal blood flow decreased by a greater extent (35, 50, and 54% at each respective IAP). Hepatic arterial blood flow more than doubled at each IAP, but this was not sufficient to maintain total liver blood flow, or presumably total oxygen delivery to liver. The marked curtailment of splanchnic blood flow suggests that prolonged periods of elevated IAP at or above 15 mm Hg should be avoided in repair of gastroschisis and omphalocele or in other situations that can produce profound abdominal distension, such as swelling from liver transplantation or gaseous distension.