Portal de Periódicos da CAPES

Intraoperative permissive oliguria – how much is too much?

2017; Elsevier BV; Volume: 119; Issue: 6 Linguagem: Inglês

10.1093/bja/aex387

1471-6771

Gudrun Kunst, Marlies Ostermann,

Trauma, Hemostasis, Coagulopathy, Resuscitation

Acute kidney injury (AKI) after general surgery is a serious complication. In abdominal surgery the incidence is around 13%, and it is associated with increased postoperative morbidity, length of hospital stay and a 13-fold increase in the relative risk of in-hospital or 30-day mortality.1O'Connor ME Kirwan CJ Pearse RM Prowle JR Incidence and associations of acute kidney injury after major abdominal surgery.Intensive Care Med. 2016; 42: 521-530Crossref PubMed Scopus (141) Google Scholar 2Singri N Ahya SN Levin ML Acute renal failure.JAMA. 2003; 289: 747-751Crossref PubMed Scopus (164) Google Scholar Oliguria is one of the oldest markers of AKI, and was historically described by Epheseus and Galen in 100–200 AD.3Eknoyan G Rufus of ephesus and his "diseases of the kidneys".Nephron. 2002; 91: 383-390Crossref PubMed Scopus (23) Google Scholar 4Eknoyan G The origins of nephrology-Galen, the founding father of experimental renal physiology.Am J Nephrol. 1989; 9: 66-82Crossref PubMed Scopus (44) Google Scholar By consensus, oliguria is defined as urine output <0.5 ml kg−1 h−1.5Bellomo R Ronco C Kellum JA Mehta RL Palevsky P Acute Dialysis Quality Initiative workgroup Acute renal failure—definition, outcome measures, animal models, fluid therapy and information technology needs: the Second International Consensus Conference of the Acute Dialysis Quality Initiative (ADQI) Group.Crit Care. 2004; 8: R204-R212Crossref PubMed Google Scholar Perioperative causes of oliguria include intravascular hypovolaemia, prolonged hypotension and reduced perfusion of the kidneys, but also non-renal causes such as release of anti-diuretic hormone (ADH) in response to nausea or pain. In the critical care setting, oliguria is common, and often considered as an early marker of renal injury, preceding a rise in creatinine.6Macedo E Malhotra R Bouchard J Wynn SK Mehta RL Oliguria is an early predictor of higher mortality in critically ill patients.Kidney Int. 2011; 80: 760-767Abstract Full Text Full Text PDF PubMed Scopus (177) Google Scholar, 7Prowle JR Liu YL Licari E et al.Oliguria as predictive biomarker of acute kidney injury in critically ill patients.Crit Care. 2011; 15: R172Crossref PubMed Scopus (165) Google Scholar, 8Piccinni P Cruz DN Gramaticopolo S et al.Prospective multicenter study on epidemiology of acute kidney injury in the ICU: a critical care nephrology Italian collaborative effort (NEFROINT).Minerva Anestesiol. 2011; 77: 1072-1083PubMed Google Scholar Multiple studies in critical care patients with AKI demonstrated an association between oliguria and mortality.9Brivet FG Kleinknecht DJ Loirat P Landais PJ Acute renal failure in intensive care units–causes, outcome, and prognostic factors of hospital mortality; a prospective, multicenter study. French Study Group on Acute Renal Failure.Crit Care Med. 1996; 24: 192-198Crossref PubMed Scopus (757) Google Scholar 10Guerin C Girard R Selli JM Perdrix JP Ayzac L Initial versus delayed acute renal failure in the intensive care unit. A multicenter prospective epidemiological study. Rhone-Alpes Area Study Group on Acute Renal Failure.Am J Respir Crit Care Med. 2000; 161: 872-879Crossref PubMed Scopus (170) Google Scholar Recently, Teixeira and colleagues11Teixeira C Garzotto F Piccinni P et al.Fluid balance and urine volume are independent predictors of mortality in acute kidney injury.Crit Care. 2013; 17: R14Crossref PubMed Scopus (175) Google Scholar confirmed in an observational multicentre study of 601 critical care patients that oliguria per se was independently associated with mortality. In contrast to oliguria in the critical care setting, intraoperative oliguria appears to be less reliable in predicting AKI as was already suggested 30 yr ago in patients undergoing abdominal aortic surgery.12Alpert RA Roizen MF Hamilton WK et al.Intraoperative urinary output does not predict postoperative renal function in patients undergoing abdominal aortic revascularization.Surgery. 1984; 95: 707-711PubMed Google Scholar 13Knos GB Berry AJ Isaacson IJ Weitz FI Intraoperative urinary output and postoperative blood urea nitrogen and creatinine levels in patients undergoing aortic reconstructive surgery.J Clin Anesth. 1989; 1: 181-185Abstract Full Text PDF PubMed Scopus (21) Google Scholar More recent studies indicated that oliguria during general anaesthesia was a result of reduced clearance and slower distribution of fluids administered intraoperatively and therefore potentially unrelated to renal function.14Hahn RG Volume kinetics for infusion fluids.Anesthesiology. 2010; 113: 470-481Crossref PubMed Scopus (141) Google Scholar 15Norberg A Hahn RG Li H et al.Population volume kinetics predicts retention of 0.9% saline infused in awake and isoflurane-anesthetized volunteers.Anesthesiology. 2007; 107: 24-32Crossref PubMed Scopus (58) Google Scholar Intraoperatively, urine output is not only influenced by haemodynamics but also sympathetic tone, aldosterone and ADH levels. Increased intra-abdominal pressure independent of fluid status and blood pressure might also contribute, as shown by two studies in laparoscopic surgery.16Nguyen NT Perez RV Fleming N Rivers R Wolfe BM Effect of prolonged pneumoperitoneum on intraoperative urine output during laparoscopic gastric bypass.J Am Coll Surg. 2002; 195: 476-483Abstract Full Text Full Text PDF PubMed Scopus (108) Google Scholar 17Nishio S Takeda H Yokoyama M Changes in urinary output during laparoscopic adrenalectomy.BJU Int. 1999; 83: 944-947Crossref PubMed Scopus (53) Google Scholar A large retrospective study in 15-100 patients undergoing abdominal surgery demonstrated that intraoperative oliguria did not predict postoperative AKI.18Kheterpal S Tremper KK Englesbe MJ et al.Predictors of postoperative acute renal failure after noncardiac surgery in patients with previously normal renal function.Anesthesiology. 2007; 107: 892-902Crossref PubMed Scopus (389) Google Scholar Based on existing studies, one can conclude that the nature and impact of intraoperative oliguria or 'permissive oliguria' in anaesthetised patients undergoing elective surgery depends on patient characteristics and clinical conditions, and may not necessarily be associated with postoperative AKI.19Goren O Matot I Perioperative acute kidney injury.Br J Anaesth. 2015; 115: ii3-i14Abstract Full Text Full Text PDF PubMed Scopus (133) Google Scholar 20Miller TE Roche AM Mythen M Fluid management and goal-directed therapy as an adjunct to Enhanced Recovery After Surgery (ERAS).Can J Anaesth. 2015; 62: 158-168Crossref PubMed Scopus (146) Google Scholar Despite many years of intensified research into novel AKI biomarkers, the ideal renal serum biomarker with qualities equivalent to cardiac injury serum biomarkers such as troponin or cardiac myosin-binding protein C21Kaier TE Twerenbold R Puelacher C et al.Direct Comparison of Cardiac Myosin-Binding Protein C with Cardiac Troponins for the Early Diagnosis of Acute Myocardial Infarction. Circulation.doi:10.1161/CIRCULATIONAHA.117.028084Google Scholar has not yet been identified. However, recent studies have shown promising results with the use of cell cycle arrest markers as urine kidney injury biomarkers.22Gocze I Jauch D Gotz M et al.Biomarker-guided Intervention to Prevent Acute Kidney Injury After Major Surgery: The Prospective Randomized BigpAK Study. Ann Surg.doi: 10.1097/SLA.0000000000002485Google Scholar In perioperative oliguric patients, a functional kidney injury biomarker, in contrast to creatinine, would be helpful to guide clinicians in adequately assessing whether reduced intraoperative urine output is within the range of permissive oliguria, or a sign of impending AKI. In this issue of the British Journal of Anaesthesia, the correlation between the threshold of reduced intraoperative urine output and risk of postoperative AKI in non-cardiac surgery is addressed for the first time.23Mizota T Yamamoto Y Hamada M et al.Intraoperative oliguria predicts acute kidney injury after major abdominal surgery.Br J Anaesth. 2017; 119: 1127-1134Abstract Full Text Full Text PDF PubMed Scopus (67) Google Scholar Mizota and colleagues describe in this single centre retrospective cohort study, including 3560 patients undergoing major abdominal surgery, that intraoperative urine output of < 0.3 ml kg−1 h−1 is independently associated with postoperative AKI, increasing the risk of AKI by 2.7-fold. The incidence of AKI was 6.3% (n=226). There was no correlation between reduced urine output of 0.3–0.5 ml kg−1 h−1 and AKI. These results confirm and support previous observational studies demonstrating lack of correlation between intraoperative oliguria (i.e. <0.5 ml kg−1 h−1) and postoperative outcomes in non-cardiac surgery.18Kheterpal S Tremper KK Englesbe MJ et al.Predictors of postoperative acute renal failure after noncardiac surgery in patients with previously normal renal function.Anesthesiology. 2007; 107: 892-902Crossref PubMed Scopus (389) Google Scholar As such, they question the routinely adopted oliguria cut-off of 0.5 ml kg−1 h−1, suggesting that 0.3 ml kg−1 h−1 is clinically more relevant, as with the lower cut-off of < 0.3 ml kg−1 h−1 there is a significant correlation between intraoperative oliguria and AKI. One of the strengths of the study by Mizota and colleagues is that patients receiving diuretics were excluded in order to avoid bias, which is in contrast to previous trials that assessed the effect of intraoperative urine output on postoperative AKI.18Kheterpal S Tremper KK Englesbe MJ et al.Predictors of postoperative acute renal failure after noncardiac surgery in patients with previously normal renal function.Anesthesiology. 2007; 107: 892-902Crossref PubMed Scopus (389) Google Scholar 24Hori D Katz NM Fine DM et al.Defining oliguria during cardiopulmonary bypass and its relationship with cardiac surgery-associated acute kidney injury.Br J Anaesth. 2016; 117: 733-740Abstract Full Text Full Text PDF PubMed Scopus (26) Google Scholar In addition, the authors define for the first time a potentially clinically relevant threshold for intraoperative reduced urine output, based on a large observational single centre study rather than consensus. The clinical relevance of this suggested intraoperative oliguria cut-off of 0.3 ml kg−1 h−1 will now need to be further addressed in different and potentially more heterogeneous populations. For example, Hori and colleagues24Hori D Katz NM Fine DM et al.Defining oliguria during cardiopulmonary bypass and its relationship with cardiac surgery-associated acute kidney injury.Br J Anaesth. 2016; 117: 733-740Abstract Full Text Full Text PDF PubMed Scopus (26) Google Scholar suggest that urine output during cardiopulmonary bypass of < 1.5 ml kg−1 h−1 identifies patients at risk of cardiac surgery-associated AKI. A critical oliguria cut-off has been assessed in the critical care setting before. Md Ralib and colleagues25Md Ralib A Pickering JW Shaw GM Endre ZH The urine output definition of acute kidney injury is too liberal.Crit Care. 2013; 17: R112Crossref PubMed Scopus (93) Google Scholar showed that a six-h urine output threshold of 0.3 ml kg−1 h−1 was superior to a threshold of 0.5 ml kg−1 h−1 in independently predicting hospital and one-year mortality. The authors concluded that 0.5 ml kg−1 h−1 as a urine output criterion for AKI based on consensus might be too liberal. Others, like Prowle and colleagues7Prowle JR Liu YL Licari E et al.Oliguria as predictive biomarker of acute kidney injury in critically ill patients.Crit Care. 2011; 15: R172Crossref PubMed Scopus (165) Google Scholar suggest that the duration of oliguria is important. The occurrence of short periods (one to six hours) of oliguria lacked utility in discriminating patients with incipient AKI. Finally, the National Kidney Foundation-Kidney Disease Outcomes Quality Initiative (NKF-KDOQI) and a working group of the European Renal Best Practice previously raised concerns that the use of weight based urine output criteria of 0.5 ml kg−1 h−1 might over-diagnose AKI and trigger harmful actions, in particular in obese patients.26Palevsky PM Liu KD Brophy PD et al.KDOQI US commentary on the 2012 KDIGO clinical practice guideline for acute kidney injury.Am J Kidney Dis. 2013; 61: 649-672Abstract Full Text Full Text PDF PubMed Scopus (442) Google Scholar 27Ad-Hoc Working Group Of ERPB Fliser D Laville M et al.A European Renal Best Practice (ERBP) position statement on the Kidney Disease Improving Global Outcomes (KDIGO) clinical practice guidelines on acute kidney injury: part 1: definitions, conservative management and contrast-induced nephropathy.Nephrol Dial Transplant. 2012; 27: 4263-4272Crossref PubMed Scopus (390) Google Scholar It was suggested to use either ideal body weight or lower urine output criteria to avoid over-diagnosis and over-reaction. Furthermore, a study by Mandelbaum and colleagues28Mandelbaum T Lee J Scott DJ et al.Empirical relationships among oliguria, creatinine, mortality, and renal replacement therapy in the critically ill.Intensive Care Med. 2013; 39: 414-419Crossref PubMed Scopus (38) Google Scholar assessing empirical relationships between oliguria and mortality in critical care patients found that when urine output was <0.5 ml kg−1 h−1 mortality increased rapidly as urine output decreased. In addition, the mortality risk was especially sensitive to oliguria during observation periods shorter than five hours if urine output was <0.3 ml kg−1 h−1. Concern has been raised that inappropriate criteria for oliguria can lead to harmful interventions. For instance, inappropriate fluid administration to increase urine output in case of oliguria might be harmful. Potential fluid overload associated with a positive fluid balance after major surgery can increase the incidence of AKI,29Kambhampati G Ross EA Alsabbagh MM et al.Perioperative fluid balance and acute kidney injury.Clin Exp Nephrol. 2012; 16: 730-738Crossref PubMed Scopus (43) Google Scholar postoperative complications30Brandstrup B Svendsen PE Rasmussen M et al.Which goal for fluid therapy during colorectal surgery is followed by the best outcome: near-maximal stroke volume or zero fluid balance?.Br J Anaesth. 2012; 109: 191-199Abstract Full Text Full Text PDF PubMed Scopus (200) Google Scholar, 31Nisanevich V Felsenstein I Almogy G Weissman C Einav S Matot I Effect of intraoperative fluid management on outcome after intraabdominal surgery.Anesthesiology. 2005; 103: 25-32Crossref PubMed Scopus (638) Google Scholar, 32McArdle GT McAuley DF McKinley A Blair P Hoper M Harkin DW Preliminary results of a prospective randomized trial of restrictive versus standard fluid regime in elective open abdominal aortic aneurysm repair.Ann Surg. 2009; 250: 28-34Crossref PubMed Scopus (87) Google Scholar and length of hospital stay.32McArdle GT McAuley DF McKinley A Blair P Hoper M Harkin DW Preliminary results of a prospective randomized trial of restrictive versus standard fluid regime in elective open abdominal aortic aneurysm repair.Ann Surg. 2009; 250: 28-34Crossref PubMed Scopus (87) Google Scholar 33Lobo DN Bostock KA Neal KR Perkins AC Rowlands BJ Allison SP Effect of salt and water balance on recovery of gastrointestinal function after elective colonic resection: a randomised controlled trial.Lancet. 2002; 359: 1812-1818Abstract Full Text Full Text PDF PubMed Scopus (830) Google Scholar Pathophysiologically, liberal fluid therapy might lead to fluid overload and tissue oedema, which in encapsulated organs such as the kidneys results in obstruction of capillary blood flow, increase in interstitial pressure, and compromised organ blood flow, leading to AKI.34Prowle JR Echeverri JE Ligabo EV Ronco C Bellomo R Fluid balance and acute kidney injury.Nat Rev Nephrol. 2010; 6: 107-115Crossref PubMed Scopus (322) Google Scholar For example in bariatric laparoscopic surgery, using reduced urine output as a trigger for routine fluid administration to augment diuresis was recently considered as 'futile'.35Matot I Paskaleva R Eid L et al.Effect of the volume of fluids administered on intraoperative oliguria in laparoscopic bariatric surgery: a randomized controlled trial.Arch Surg. 2012; 147: 228-234Crossref PubMed Scopus (61) Google Scholar Miller and colleagues20Miller TE Roche AM Mythen M Fluid management and goal-directed therapy as an adjunct to Enhanced Recovery After Surgery (ERAS).Can J Anaesth. 2015; 62: 158-168Crossref PubMed Scopus (146) Google Scholar suggested the term 'permissive oliguria', in order to avoid harm from over-treating intraoperative oliguria. A recent meta-analysis including 36 randomized controlled trials in perioperative medicine and critical care demonstrated that targeting urine output does not affect 30-day mortality, suggesting that oliguria is not a modifiable risk factor for mortality.36van der Zee EN Egal M Gommers D Groeneveld AB Targeting urine output and 30-day mortality in goal-directed therapy: a systematic review with meta-analysis and meta-regression.BMC Anesthesiol. 2017; 17: 22Crossref PubMed Scopus (10) Google Scholar On the other hand, accepting a low urine output caused by hypovolaemia including the associated haemodynamic effects might result in reduced kidney perfusion and kidney injury. The study by Mizota and colleagues in this issue of the BJA suggests that oliguria with a threshold of < 0.3 ml kg−1 h−1 might be an appropriate early intraoperative indicator of AKI. If adopted, this might avoid negative outcomes associated with fluid treatments aimed at increasing urine output. Interestingly, a collaborative North American/European survey from 2011 demonstrated that in high-risk surgical patients, perioperative urine output was the second most common indicator for intraoperative volume expansion and also for fluid responsiveness (the most common trigger was low blood pressure).37Cannesson M Pestel G Ricks C Hoeft A Perel A Hemodynamic monitoring and management in patients undergoing high risk surgery: a survey among North American and European anesthesiologists.Crit Care. 2011; 15: R197Crossref PubMed Scopus (224) Google Scholar This was reported despite overall agreement that the most frequent parameters for perioperative fluid optimization should also include cardiac output and/or oxygen delivery. Whether the results of this single centre study by Mizota and colleagues23Mizota T Yamamoto Y Hamada M et al.Intraoperative oliguria predicts acute kidney injury after major abdominal surgery.Br J Anaesth. 2017; 119: 1127-1134Abstract Full Text Full Text PDF PubMed Scopus (67) Google Scholar are generalizable and whether an oliguria threshold of 0.3 ml kg−1 h−1 during abdominal surgery is clinically relevant and predictive of postoperative AKI, and thus associated with postoperative morbidity, will need to be investigated in more centres. The key question of whether treatment of intraoperative urine output <0.3 ml kg−1 h−1, including fluid administration, might be beneficial for patients was not addressed in this study,23Mizota T Yamamoto Y Hamada M et al.Intraoperative oliguria predicts acute kidney injury after major abdominal surgery.Br J Anaesth. 2017; 119: 1127-1134Abstract Full Text Full Text PDF PubMed Scopus (67) Google Scholar but will need to be further explored. None declared.