Introduction. Peritonitis is one of the risk factors for the development of intra-abdominal hypertension (IAH) and abdominal compartment syndrome (ACS). The plasma citrulline and intestinal fatty acid-binding protein (I-FABP) are informative markers of intestinal barrier function. The aim of this study was to determine the correlation of the plasma citrulline and I-FABP with intra-abdominal pressure (IAP) and their relation to analgesia techniques in children suffering from appendicular peritonitis. Materials and Methods. 74 children operated for appendicular peritonitis were randomized into three groups of postoperative analgesia: “Opioids” (n = 25), intravenous morphine of 10 mcg/kg/h; “Lidocaine” (n = 23), intravenous lidocaine with initial bolus of 1.5 mg/kg and then infusion of 1.5 mg/kg/h; and “EA” (n = 26), epidurally 0.25% bupivacaine with initial bolus of 1 mg/kg and then infusion of 0.4 mg/kg/year. Retrospectively patients in each group were divided into the following subgroups: “without IAH” (n = 33), “IAH” (n = 27), and “ACS” (n = 14). We detected citrulline and I-FABP in plasma on day 1 (D1) and day 3 (D3) of hospital stay. Results. The patients without IAH on D1 presented significantly higher plasma citrulline (23.7 (16.0–31.3) nmol/ml) and lower I-FABP (76.9 (32.6–121.1) pg/ml) levels compared with patients in subgroup “IAH” (9.3 (7.3–11.3) nmol/ml and 226.0 (161.8–290.3) pg/ml, respectively) and subgroup “ACS” (6.9 (5.3–8.6) nmol/ml and 1011.7 (731.9–1291.5) pg/ml, respectively). The IAP had strong inverse correlation (r_s = −0.74; p < 0.00001) with citrulline and positive strong correlation (r_s = 0.73; p < 0.00001) with I-FABP. The citrulline in patients with IAH during three days postoperatively increased significantly in “Lidocaine” to 72% (p = 0.01) and in “EA” to 138% (p = 0.02), but it decreased to 13% (p = 0.37) in “Opioids” group. In children with ACS, citrulline on D3 was significantly higher than that on D1 and increased in “Lidocaine” to 59% (p = 0.05) and in “EA” to 134% (p = 0.001), but in “Opioids” it decreased to 30% (p = 0.48). The I-FABP in patients with IAH decreased to 12% in “Lidocaine” group (p = 0.86) and to 75% in “EA” group (p = 0.01), but it increased to 37% (p = 0.57) in “Opioids” group. During observation period, I-FABP in patients with ACS decreased significantly in “Lidocaine” to 42% (p = 0.05) and in “EA” to 96% (p = 0.003), but it increased in “Opioids” to 63% (p = 0.22). Conclusions. The IAP was inversely correlated with plasma citrulline and positively correlated with I-FABP in children with appendicular peritonitis. Epidural analgesia is the most protective for intestinal wall barrier function in patients at risk of IAH and ACS.

Background and Aims: Intraabdominal hypertension (IAH) is poorly diagnosed condition that cause splanchnic hypoperfusion
and abdominal organs ischemia and can lead to multiple organ failure. There are no scientific data regarding effect of intraabdominal pressure (IAP) on splanchnic circulation in children.
Material and Methods: Ninety‑four children after surgery for appendicular peritonitis were enrolled in the study. After IAP measurement children were included in one of two groups according IAP levels: “without IAH” (n = 51) and “with IAH” (n = 43). Superior mesenteric artery (SMA) and portal vein (PV) blood flows (BFSMA, BFPV, mL/min) were measured, and SMA and PV blood flow indexes (BFISMA, BFIPV, ml/min*m2) and abdominal perfusion pressure (APP) were calculated in both groups.
Results: Median BFISMA and BFIPV in group “with IAH” were lower by 54.38% (P ˂ 0.01) and 63.11% (P < 0.01) respectively compared to group “without IAH”. There were strong significant negative correlation between IAP and BFISMA (rs  = –0.66; P ˂ 0.0001), weak significant negative correlation between IAP and BFIPV (rs = –0.36; P = 0.0001) in group “with IAH” and weak significant negative correlation between IAP and BFISMA (rs = –0.30; P = 0.0047) in group “without IAH”. There were no statistically significant correlations between IAP and BFIPV in group “without IAH”, between BFISMA and APP in both groups and between BFIPV and APP in both groups.
Conclusion: Elevated IAP significantly reduces splanchnic blood flow in children with appendicular peritonitis. BFISMA and BFIPV negatively correlate with IAP in these patients. There is no correlation between BFISMA/BFIPV and APP in children with IAH due to appendicular peritonitis.