Data from: Plasma pro-atrial natriuretic peptide to indicate fluid balance during cystectomy: a prospective observational study

Objectives: During surgery the volume of administered fluid is debated. Pro-atrial natriuretic peptide (proANP) is released by atrial distension, and we evaluated the relationship between changes in proANP associated with perioperative fluid balance. Design: Prospective observational study. Setting: One university/tertiary centre. Participants: The study included patients who underwent radical cystectomy. Plasma for determination of proANP was obtained before surgery, after resection of the bladder, and at the end of surgery for 20 robotic-assisted radical cystectomy (RARC) and 20 open radical cystectomy (ORC) procedures. Results: The blood loss was 1871 (95% CI 1267 to 2475) vs 589 mL (378 to 801) in the ORC and RARC groups (p=0.001), respectively, and fluid balance was positive by 1518 mL (1215 to 1821) during ORC, and by 1858 mL (1461 to 2255) during RARC (p=0.163). Yet, at the end of ORC, plasma proANP was reduced by 23% (14% to 32%, p=0.001), while plasma proANP did not change significantly during RARC. Thus, plasma proANP was associated both with the perioperative blood loss (r= −0.475 (0.632 to −0.101), p=0.002), and with fluid balance (r=0.561 (0.302 to 0.740), p=0.001), indicating that a stable plasma proANP required a fluid surplus by 2.4 L (2.0 to 2.7). Conclusions: There was a correlation between intraoperative haemorrhage and a decrease in plasma proANP and, taking plasma proANP to indicate filling of the heart, about 2.5 L surplus volume of lactated Ringer's solution appears to maintain cardiac preload during cystectomy.研究目的：术中输注液体的剂量一直存在学术争议。心房利钠肽前体（pro-atrial natriuretic peptide, proANP）由心房扩张时释放，本研究旨在探讨围手术期液体平衡相关的proANP变化之间的关联。研究设计：前瞻性观察性研究。研究场所：一所大学附属三级医疗中心。研究对象：纳入接受根治性膀胱切除术的患者。分别于术前、膀胱切除术后及手术结束时采集血浆样本以检测proANP水平，共纳入20例机器人辅助根治性膀胱切除术（robotic-assisted radical cystectomy, RARC）患者与20例开放根治性膀胱切除术（open radical cystectomy, ORC）患者。结果：ORC组与RARC组的失血量分别为1871 mL（95%置信区间[CI]：1267~2475）与589 mL（95%CI：378~801），组间差异具有统计学意义（p=0.001）；ORC组围手术期液体平衡为正1518 mL（95%CI：1215~1821），RARC组为正1858 mL（95%CI：1461~2255），组间差异无统计学意义（p=0.163）。然而，ORC组手术结束时血浆proANP水平降低了23%（95%CI：14%~32%，p=0.001），而RARC组血浆proANP水平无显著变化。进一步分析显示，血浆proANP水平与围手术期失血量呈负相关（r=-0.475，95%CI：-0.632~-0.101，p=0.002），与液体平衡呈正相关（r=0.561，95%CI：0.302~0.740，p=0.001），提示维持血浆proANP水平稳定所需的液体盈余量为2.4 L（95%CI：2.0~2.7）。结论：术中失血量与血浆proANP水平降低存在相关性；若以血浆proANP水平反映心脏充盈状态，则根治性膀胱切除术中约需2.5 L乳酸林格液盈余量以维持心脏前负荷。