Positive fluid balance is associated with complications after elective open infrarenal abdominal aortic aneurysm repair

Association between estimated plasma volume status and acute kidney injury in patients who underwent coronary revascularization: A retrospective cohort study from the MIMIC-IV database

BACKGROUND

Acute kidney injury (AKI) remains a common complication of coronary revascularization and increases poor outcomes in critically ill surgical patients. Compared to the plasma volume status (PVS), estimated plasma volume status (ePVS) has the advantages of being noninvasive and simple and has been shown to be associated with worse prognosis in patients undergoing coronary revascularization. This study was to evaluate the association of ePVS with the risk of AKI in patients who underwent coronary revascularization.

METHODS

In this retrospective cohort study, data of patients who underwent coronary revascularization were extracted from the Medical Information Mart for Intensive Care (MIMIC)-IV database (2008-2019). The outcome was the occurrence of AKI after ICU admission. The covariates were screened via the LASSO regression method. Univariate and multivariate Logistic regression models were performed to assess the association of ePVS and PVS and the odds of AKI in patients who underwent coronary revascularization, with results shown as odds ratios (ORs) and 95% confidence intervals (CIs). Subgroup analyses of age, surgery, and anticoagulation agents and sequential organ failure assessment (SOFA) score were performed to further explore the association of ePVS with AKI.

RESULTS

A total of 3,961 patients who underwent coronary revascularization were included in this study, of whom 2,863 (72.28%) had AKI. The high ePVS was associated with the higher odds of AKI in patients who received coronary revascularization (OR = 1.06, 95%CI: 1.02-1.10), after adjusting for the covariates such as age, race, SAPS-II score, SOFA score, CCI, weight, heart rate, WBC, RDW-CV, PT, BUN, glucose, calcium, PH, PaO2, mechanical ventilation, vasopressors, and diuretic. Similar results were found in patients who underwent the CABG (OR = 1.07, 95%CI: 1.02-1.11), without anticoagulation agents use (OR = 1.07, 95%CI: 1.03-1.12) and with high SOFA score (OR = 1.10, 95%CI: 1.04-1.17). No relationship was found between PVS and the odds of AKI in patients who underwent the coronary revascularization.

CONCLUSION

The ePVS may be a promising parameter to evaluate the risk of AKI in patients undergoing coronary revascularization, which provides a certain reference for the risk stratification management of ICU patients who underwent coronary revascularization.

Objective Methods of Assessing Fluid Status to Optimize Volume Management in Kidney Disease and Hypertension: The Importance of Ultrasound

Fluid overload, a prevalent complication in patients with renal disease and hypertension, significantly impacts patient morbidity and mortality. The daily clinical challenges that clinicians face include how to identify fluid overload early enough in the course of the disease to prevent adverse outcomes and to guide and potentially reduce the intensity of the diuresis. Traditional methods for evaluating fluid status, such as pitting edema, pulmonary crackles, or chest radiography primarily assess extracellular fluid and do not accurately reflect intravascular volume status or venous congestion. This review explores the rationale, mechanism, and evidence behind more recent methods used to assess volume status, namely, lung ultrasound, inferior vena cava (IVC) ultrasound, venous excess ultrasound score, and basic and advanced cardiac echocardiographic techniques. These methods offer a more accurate and objective assessment of fluid status, providing real-time, non-invasive measures of intravascular volume and venous congestion. The methods we discuss are primarily used in inpatient settings, but, given the increased pervasiveness of ultrasound technology, some could soon expand to the outpatient setting.

A Rare Case of Abdominal Aortic Aneurysm with Ureteral Compression

Introduction: In this report, we present a rare case of aortic aneurysm with associated left ureter obstruction and consequent hydronephrosis.

Case presentation: A 62-year-old man was admitted for epigastric and periumbilical pain, extended in the spine, and anuria. As for associated diseases, he presented arterial hypertension stage II/III, chronic ischemic cardiomyopathy, acidosis, hyperpotassemia, spondylosis with radiculopathy, acute renal failure, renal lithiasis, and eating difficulties. After performing a CT scan, the patient was diagnosed with giant abdominal infrarenal aortic aneurysm with ureter compression, and retroperitoneal rupture with common and internal iliac arteries occlusion. We performed a xifo-pubian laparotomy with endoaneurysmorrhaphy and aortoiliac bilateral bypass using silver Dacron vascular prosthesis (16 × 8 mm in diameter). Douglas drainage was necessary, ending with laparoraphy. The patient presented a favorable postoperative evolution.

Conclusion: Open surgery remains the gold standard method of treatment for large aortic aneurysms, given the inability of endovascular procedures to solve problems caused by compression.

Early perioperative fluid overload is associated with adverse outcomes in deceased donor kidney transplantation

Kidney transplant recipients are often treated with a large volume of infusion to attain adequate graft perfusion in the early perioperative period. However, it remains unknown whether this fluid therapy is renal responsive or a contributing factor to fluid overload complications. We conducted a retrospective cohort analysis of all recipients who received deceased donor kidney transplantation at an academic teaching hospital from January 2015 to April 2019. Our exposure of interest was early perioperative fluid balance. The primary outcome was graft function at 1, 6, and 12 months after transplantation. The secondary outcome was cardiopulmonary and gastrointestinal complications. Fluid balance was not significantly correlated with graft function in short- or long-term periods. Postoperative complications were higher in recipients with increased fluid balance. Delayed graft function was significantly related to cardiopulmonary and gastrointestinal complications. Cardiovascular disease and high BMI of recipients were strong risk factors for cardiopulmonary complications. Fluid overload was prevalent in the early perioperative period of kidney transplantation. It did not promote renal recovery, but was associated with a high risk of complications. Our findings might be a useful indicator to optimize the perioperative fluid management of kidney transplant recipients.

Hypertonic saline for fluid resuscitation in ICU patients post-cardiac surgery (HERACLES): a double-blind randomized controlled clinical trial

PURPOSE

Recent evidence questions a liberal approach to fluid resuscitation in intensive care unit (ICU) patients. Here, we assess whether use of hypertonic saline applied as single infusion at ICU admission after cardiac surgery can reduce cumulative perioperative fluid volume.

METHODS

Prospective randomized double-blind single-center clinical trial investigates effects of a single infusion of hypertonic saline (HS) versus normal saline (comparator). Primary endpoint was the cumulative amount of fluid administered in patients in the hypertonic saline versus the 0.9% saline groups (during ICU stay). Upon ICU admission, patients received a single infusion of 5 ml/kg body weight of 7.3% NaCl (or 0.9% NaCl) over 60 min. Patients undergoing cardiac surgery for elective valvular and/or coronary heart disease were included. Patients with advanced organ dysfunction, infection, and/or patients on chronic steroid medication were excluded.

RESULTS

A total of 101 patients were randomized to receive the study intervention (HS n = 53, NS n = 48). Cumulative fluid intake on the ICU (primary endpoint) did not differ between the HS and the NS groups [median 3193 ml (IQR 2052-4333 ml) vs. 3345 ml (IQR 2332-5043 ml)]. Postoperative urinary output until ICU discharge was increased in HS-treated patients [median 2250 ml (IQR 1640-2690 ml) vs. 1545 ml (IQR 1087-1976 ml)], and ICU fluid balance was lower in the HS group when compared to the NS group [296 ml (IQR - 441 to 1412 ml) vs. 1137 ml (IQR 322-2660 ml)].

CONCLUSION

In a monocentric prospective double-blind randomized clinical trial, we observed that hypertonic saline did not reduce the total fluid volume administered on the ICU in critically ill cardiac surgery patients. Hypertonic saline infusion was associated with timely increase in urinary output. Variations in electrolyte and acid-base homeostasis were transient, but substantial in all patients.

Association Between Perioperative Fluid Balance and 30-Day Unplanned Readmission After Major Abdominal Surgery

Perioperative positive fluid balance (FB) increases postoperative complication and length of hospital stay. We aimed to investigate 30-day unplanned readmission after major abdominal surgery based on perioperative FB (%) on postoperative days (POD) 0 to 3. This retrospective cohort study analyzed medical records of patients who underwent elective major abdominal surgery (surgery time >2 hours, estimated blood loss >500 mL) at a single tertiary academic hospital from January 2010 to December 2017. Cumulative FB was calculated by total input fluid - output fluid in liters × weight (kg)^-1 on admission × 100 during POD 0 (24 hours), 0 to 1 (48 hours), 0 to 2 (72 hours), and 0 to 3 (96 hours). Of the 3650 patients in the final analysis, 503 (13.8%) had unplanned readmission within 30 days. In the multivariable logistic regression analysis, FB on POD 0 (24 hours), 0 to 1 (48 hours), 0 to 2 (72 hours), and 0 to 3 (96 hours) showed no significant association with 30-day unplanned readmission (all P > .05). However, an increase of 10 000 points in the total relative value unit scores was associated with 5% increase in 30-day unplanned readmission (odds ratio = 1.05, 95% confidence interval = 1.02-1.07; P = .001), and 1-hour increase in surgery time was associated with 10% increase in 30-day unplanned readmission (odds ratio = 1.10, 95% confidence interval = 1.05-1.15; P < .001). This study showed that perioperative FB is not associated with 30-day unplanned readmission rate after a major abdominal surgery. Total relative value unit scores and duration of surgery were significantly associated with 30-day unplanned readmission rate after major abdominal surgery in a single tertiary academic hospital.

Calculated plasma volume status and outcomes in patients undergoing coronary bypass graft surgery

OBJECTIVES

Congestion is associated with worse outcomes in critically ill surgical patients but can be difficult to quantify noninvasively. We hypothesised that plasma volume status (PVS), estimated preoperatively using a validated formula that enumerates percentage change from ideal plasma volume (PV), would provide incremental prognostic utility after coronary artery bypass graft (CABG) surgery.

METHODS

In this retrospective cohort study, patients who underwent CABG surgery (1999-2010) were identified from a prospectively collected database. Actual ([1-haematocrit] x [a+(b x weight [kg])]) and ideal (c x weight [kg]) PV were obtained from equations where a, b and c are sex-dependent constants. Calculated PVS was then derived (100% x [(actual-ideal)/ideal]).

RESULTS

In 1887 patients (mean age 67±10 years; 79% male; median European System for Cardiac Operative Risk Evaluation [EuroSCORE] 4), mean PVS was -8.2±9%. While 8% of subjects had clinical evidence of congestion, a relatively increased PV (PVS >0%) was estimated in 17% and correlated with lower serum sodium, higher EuroSCORE and a diagnosis of diabetes mellitus. A PVS≥5.6% was optimally prognostic and associated with greater mortality (HR: 2.31, p=0.009), independently of, and incremental to, EuroSCORE, New York Heart Association class and serum sodium. A PVS≥5.6% also independently predicted longer intensive care (β: 0.65, p=0.007) and hospital (β: 2.01, p=0.006) stays, and greater postoperative renal (OR: 1.61, p=0.008) and arrhythmic (OR: 1.29, p=0.03) complications.

CONCLUSIONS

Higher PVS values, calculated simply from weight and haematocrit, are associated with worse inpatient outcomes after CABG. PVS could help refine risk stratification and further investigations are warranted to evaluate the potential clinical utility of PVS-guided management in patients undergoing CABG.

Perioperative Cumulative Fluid Balance and Its Association with an Increase in Costs after Major Surgery

Positive fluid balance (FB) during the perioperative period may increase the incidence of postoperative complications, which may lead to longer hospitalization and higher hospital costs. However, a definitive association between positive FB and hospital costs has not yet been established. This retrospective observational study examined the association between perioperative FB and hospital costs of patients who underwent major surgical procedures. Medical records of patients who underwent major surgery (surgery time >2 h, estimated blood loss >500 mL) from January 2010 to December 2017 were analyzed to determine the associations between calculated FB (%, total input fluid—output fluid in liter/weight (kg) at admission) and total hospital cost ($). The analysis included medical data of 7010 patients. Multivariable linear regression analyses showed that a 1% increase in FB in postoperative day (POD) 0 (24 h), 0–1 (48 h), 0–2 (72 h), and 0–3 (96 h) significantly increased the total cost by $967.8 (95% confidence interval [CI]: 803.4–1132.1), $688.8 (95% CI: 566.3–811.2), $591 (95% CI: 485.7–696.4), and $434.2 (95% CI: 349.4–519.1), respectively (all p < 0.001). Perioperative cumulative FB was positively associated with hospital costs of patients who underwent major surgery.

Intravenous Fluid Challenge Decreases Intracellular Volume: A Bioimpedance Spectroscopy-Based Crossover Study in Healthy Volunteers

The effects of intravenous fluid therapy on fluid compartments and hemodynamics of the human body remain enigmatic. We therefore tested the efficacy of bioimpedance spectroscopy in a crossover study, where 15 males received 0.5 ml/kg/min ELO-MEL-isoton (osmolarity = 302 mosmol/l) during 60 minutes, or nothing at all. In group “Fluid”, fluid load increased from −0.2 ± 1.0 l extracellular volume at baseline to its maximum of 1.0 ± 0.9 l in minute 70, and remained continuously elevated throughout minute 300. In group “Zero”, fluid load decreased from 0.5 ± 1.1 l at baseline to its minimum of −1.1 ± 1.1 l in minute 300. In group “Fluid”, intracellular volume decreased from 26.8 ± 3.9 l at baseline to its minimum of 26.0 ± 3.9 l in minute 70, and remained continuously decreased throughout minute 300. In group “Zero”, intracellular volume increased from 26.5 ± 3.8 l at baseline to its maximum of 27.1 ± 3.9 l in minute 120, and decreased thereafter. In group “Fluid” compared to “Zero”, systolic blood pressure was significantly higher, from minute 50–90. In conclusion, intravenous fluid therapy caused a clinically meaningful, sustained increase in fluid load, and a decrease in intracellular volume. These data raise interest in studying fluid administration by the gastrointestinal route, perhaps even when managing critical illness.

Current perioperative practice in Canadian vascular surgery

BACKGROUND

The Enhanced Recovery After Surgery (ERAS) Society has set out to improve patient recovery by developing evidence-based perioperative practices. Many institutions and other specialties have begun to apply their principles with great success; however, ERAS principles focus mostly on general surgery, and their applicability to other specialties, such as vascular surgery, is less clear. We sought to investigate the current standard of perioperative care in Canadian vascular surgery by assessing surgeons' perceptions of evidence supporting ERAS practices, identifying barriers to aligning them and identifying aspects of perioperative care that require research specific to vascular surgery before they could be broadly applied.

METHODS

We administered an online survey with 26 questions to all Canadian Society for Vascular Surgery members.

RESULTS

Respondents varied largely in perioperative practice, most notably in the use of nasogastric tubes, Foley catheters and neck drains. Familiarity with supporting evidence was poor. Approximately half (44%) of respondents were not familiar with contrary evidence, while those who were often perceived institutional barriers to change. Finally, one-third (30%) of respondents felt that relevant evidence did not exist to support changing their practice.

CONCLUSION

The variability of perioperative practice in Canadian vascular surgery is likely due to multiple factors, including a lack of specific evidence. Further research in areas of perioperative vascular care where the current standard of practice varies most greatly may help improve recovery after vascular surgery in Canada over simply adopting existing ERAS principles.

Optimal perioperative medical management of the vascular surgery patient

Perioperative medical management of patients undergoing vascular surgery can be challenging because they represent the surgical population at highest risk. β-Blockers should be continued perioperatively in patients already taking them preoperatively. Statins may be used in the perioperative period in patients who are not on statin therapy preoperatively. Institutional guidelines should be used to guide insulin replacement. Recent research suggests that measurement of troponins may provide some risk stratification in clinically stable patients following vascular surgery. Multimodal pain therapy including nonopioid strategies is necessary to improve the efficacy of pain relief and decrease the risk of side effects and complications.

Clinical Assessment of Fluid Balance is Incomplete for Colorectal Surgical Patients

Background and Aims:

Fluid balance for the surgical patient has been proven very important for the postoperative outcome and development of complications. The aim of this study was to evaluate, for the first time in modern times, the accordance between nurse-based fluid charting (cumulated fluid balance) and body weight change for general surgical patients.

Material and Methods:

This was a descriptive study with prospectively collected data from two clinical randomized multicenter trials. A total of 113 patients from American Society of Anesthesiology group I–III undergoing elective colorectal surgery were included. Cumulated fluid balance and body weight change were charted preoperatively and daily at the same time during a postoperative period of 6 days. Differences were calculated by subtracting cumulated fluid balance from body weight change (1 g = 1 mL), and agreement was assessed by making Bland–Altman plots as well as Pearson correlations.

Results:

From day 1 to 4, the mean difference between cumulated fluid balance and body weight change was below 0.4 kg/L. On day 5 and 6, the discrepancies increased with mean differences of, respectively, 1.2 kg/L (p < 0.002*) and 2 kg/L (p < 0.0001*). Bland–Altman plots showed increasingly poor agreement for all postoperative days with wide limits of agreement, ranging from more than 6 kg/L to almost 10 kg/L. Pearson correlations were moderate to strong at all times ranging from 0.437 (day 1) to 0.758 (day 4).

Conclusions:

The accordance between cumulated fluid balance and body weight change for colorectal surgical patients is relatively good for the first four postoperative days, however, with large uncertainty, whereas on the fifth and sixth postoperative day, the discrepancy is statistically and clinically significant. The fluid chart cannot stand alone in interpretation of the patient’s fluid balance; body weight and clinical judgment is indispensable.

Perioperative Haemodynamic Optimisation

During the latest years, a number of studies have confirmed the benefits of perioperative haemodynamic optimisation on surgical mortality and postoperative complication rate. This process requires the use of advanced haemodynamic monitoring with the purpose of guiding therapies to reach predefined goals. This review aim to present recent evidence on perioperative goal directed therapy (GDT), with an emphasis in some aspects that may merit further investigation. In order to maximise the benefits on outcomes, GDT must be implemented as early as possible; intravascular volume optimisation should be in accordance with the response of the preload-reserve, goals should be individualised and adequacy of the intervention must be also assessed; non-invasive or minimally invasive monitoring should be used and, finally, side effects of every therapy should be taken into account in order to avoid undesired complications. New drugs and technologies, particularly those exploring the venous side of the circulation, may improve in the future the effectiveness and facilitate the implementation of this group of therapeutic interventions.

A systematic review of goal directed fluid therapy: rating of evidence for goals and monitoring methods

PURPOSE

To review the literature on goal directed fluid therapy and evaluate the quality of evidence for each combination of goal and monitoring method.

MATERIALS AND METHODS

A search of major digital databases and hand search of references was conducted. All studies assessing the clinical utility of a specific fluid therapy goal or set of goals using any monitoring method were included. Data was extracted using a pre-determined pro forma and papers were evaluated using GRADE principles to assess evidence quality.

RESULTS

Eighty-one papers met the inclusion criteria, investigating 31 goals and 22 methods for monitoring fluid therapy in 13052 patients. In total there were 118 different goal/method combinations. Goals with high evidence quality were central venous lactate and stroke volume index. Goals with moderate quality evidence were sublingual microcirculation flow, the oxygen extraction ratio, cardiac index, cardiac output, and SVC collapsibility index.

CONCLUSIONS

This review has highlighted the plethora of goals and methods for monitoring fluid therapy. Strikingly, there is scant high quality evidence, in particular for non-invasive G/M combinations in non-operative and non-intensive care settings. There is an urgent need to address this research gap, which will be helped by methodologies to compare utility of G/M combinations.

Impact of anesthesia technique on the incidence of major complications after open aortic abdominal surgery: a cohort study

STUDY OBJECTIVE

To determine the risk factors of perioperative complications and the impact of intrathecal morphine (ITM) in major vascular surgery.

DESIGN

Retrospective analysis of a prospective cohort.

SETTINGS

Operating room, intensive care unit, and Postanesthesia Care Unit of a university hospital.

MEASUREMENTS

Data from 595 consecutive patients who underwent open abdominal aortic surgery between January 1997 and December 2011 were reviewed. Data were stratified into three groups based on the analgesia technique delivered: systemic analgesia (Goup SA), thoracic epidural analgesia (Group TEA), and intrathecal morphine (Group ITM). Preoperative patient characteristics, perioperative anesthetic and medical interventions, and major nonsurgical complications were recorded.

MAIN RESULTS

Patients managed with ITM (n=248) and those given thoracic epidural analgesia (n=70) required lower doses of intravenous (IV) sufentanil intraoperatively and were extubated sooner than those who received systemic analgesia (n=270). Total inhospital mortality was 2.9%, and 24.4% of patients experienced at least one major complication during their hospital stay. Intrathecal morphine was associated with a lower risk of postoperative morbidity (OR 0.51, 95% CI 0.28 - 0.89), particularly pulmonary complications (OR 0.54, 95% CI 0.31 - 0.93) and renal dysfunction (OR 0.52, 95% CI 0.29 - 0.97). Other predictors of nonsurgical complications were ASA physical status 3 and 4 (OR 1.94, 95% CI 1.07 - 3.52), preoperative renal dysfunction (OR 1.61, 95% CI 1.01 - 2.58), prolonged surgical time (OR 1.78, 95% CI 1.16 - 2.78), and the need for blood transfusion (OR 1.77, 95% CI 1.05 - 2.99).

CONCLUSIONS

This single-center study showed a decreased risk of major nonsurgical complications in patients who received neuraxial analgesia after abdominal aortic surgery.

Predictive factors of hospital stay in patients undergoing minimally invasive transforaminal lumbar interbody fusion and instrumentation

STUDY DESIGN

A single-center retrospective study.

OBJECTIVE

To identify predictors of length of stay (LOS) days in patients undergoing 1 level minimally invasive (MIS) transforaminal lumbar interbody fusions (TLIF).

SUMMARY OF BACKGROUND DATA

Recent studies suggest intraoperative fluid administration, and colloid and crystalloid administration among other intraoperative variables may prolong LOS days and increase complications. Therefore, an understanding of which preoperative, intraoperative, and immediate postoperative parameters best predict immediate LOS days will help risk stratify patients and guide decision making.

METHODS

We retrospectively reviewed 104 patients undergoing a MIS TLIF at 1 institution between 2008 and 2010. Two groups were selected on the basis of the time of discharge. Group 1 consisted of patients discharged within 24 hours after surgery and group 2 consisted of patients discharged more than 24 hours after surgery. Multiple regression analysis was performed to determine which preoperative, intraoperative, and postoperative variables were independent predictors of LOS days.

RESULTS

Seventy-eight patients (75%) with a LOS greater than 24 hours had significantly higher estimated blood loss, received more crystalloids, had higher total fluids, longer surgical time, lower end of case temperature, lower hemoglobin during hospitalization, and a lower preoperative narcotic use. Multiple regression analysis showed that significant predictors of increased LOS were postoperative creatinine, visual analogue scale score, intraoperative colloids, fluids input at the end of surgical case, crystalloid to colloid ratio, fluid balance, oxycodone (Oxycontin) use, mean percentage of fraction of inspired oxygen, and preoperative hemoglobin.

CONCLUSION

Patients undergoing 1 level MIS TLIF for degenerative conditions can overall expect a short LOS postoperatively. Multiple preoperative, intraoperative, and immediate postoperative factors can prolong the LOS in this group. This information should help the surgical team in optimizing their intraoperative patient management.

Individualized peri-operative fluid therapy facilitating early-phase recovery after liver transplantation

AIM: To investigate the correlation between peri-operative fluid therapy and early-phase recovery after liver transplantation (LT) by retrospectively reviewing 102 consecutive recipients.

METHODS: Based on whether or not the patients had pulmonary complications, the patients were categorized into non-pulmonary and pulmonary groups. Twenty-eight peri-operative variables were analyzed in both groups to screen for the factors related to the occurrence of early pulmonary complications.

RESULTS: The starting hemoglobin (Hb) value, an intra-operative transfusion > 100 mL/kg, and a fluid balance ≤ -14 mL/kg on the first day and the second or third day post-operatively were significant factors for early pulmonary complications. The extubation time, time to initial passage of flatus, or intensive care unit length of stay were significantly prolonged in patients who had not received an intra-operative transfusion ≤ 100 mL/kg or a fluid balance ≤ -14 mL/kg on the first day and the second or the third day post-operatively. Moreover, these patients had poorer results in arterial blood gas analysis.

CONCLUSION: It is important to offer a precise and individualized fluid therapy during the peri-operative period to the patients undergoing LT for cirrhosis-associated hepatocellular carcinoma.

Intraoperative fluid therapy and pulmonary complications

The purpose of this study was to evaluate the effects of intraoperative fluid therapy on length of hospital stay and pulmonary complications in patients undergoing spine surgery. A total of 1307 patients were analyzed. Sixteen pulmonary complications were observed. Patients with a higher volume of administered crystalloids, colloids, and total intravenous fluids were more likely to have postoperative respiratory complications: the odds of postoperative respiratory complications increased by 30% with an increase of 1000 mL of crystalloid administered. The best cutoff point for total fluids was 4165 mL, with a sensitivity of 0.8125 and specificity of 0.7171, for postoperative pulmonary complications. A direct correlation existed between fluids and length of stay: patients who received >4165 mL of total fluids had an average length of stay of 3.88±4.66 days vs 2.3±3.9 days for patients who received <4165 mL of total fluids (P<.0001). This study should be considered as hypothesis-generating to design a prospective trial comparing high vs low intraoperative fluid regiments for patients undergoing spine surgery.

Oliguria as predictive biomarker of acute kidney injury in critically ill patients

INTRODUCTION

During critical illness, oliguria is often used as a biomarker of acute kidney injury (AKI). However, its relationship with the subsequent development of AKI has not been prospectively evaluated.

METHODS

We documented urine output and daily serum creatinine concentration in patients admitted for more than 24 hours in seven intensive care units (ICUs) from six countries over a period of two to four weeks. Oliguria was defined by a urine output < 0.5 ml/kg/hr. Data were collected until the occurrence of creatinine-defined AKI (AKI-Cr), designated by RIFLE-Injury class or greater using creatinine criteria (RIFLE-I[Cr]), or until ICU discharge. Episodes of oliguria were classified by longest duration of consecutive oliguria during each day were correlated with new AKI-Cr the next day, examining cut-offs for oliguria of greater than 1,2,3,4,5,6, or 12 hr duration,

RESULTS

We studied 239 patients during 723 days. Overall, 32 patients had AKI on ICU admission, while in 23, AKI-Cr developed in ICU. Oliguria of greater than one hour was significantly associated with AKI-Cr the next day. On receiver-operator characteristic area under the curve (ROCAUC) analysis, oliguria showed fair predictive ability for AKI-Cr (ROCAUC = 0.75; CI:0.64-0.85). The presence of 4 hrs or more oliguria provided the best discrimination (sensitivity 52% (0.31-0.73%), specificity 86% (0.84-0.89%), positive likelihood ratio 3.8 (2.2-5.6), P < 0.0001) with negative predictive value of 98% (0.97-0.99). Oliguria preceding AKI-Cr was more likely to be associated with lower blood pressure, higher heart rate and use of vasopressors or inotropes and was more likely to prompt clinical intervention. However, only 30 of 487 individual episodes of oliguria preceded the new occurrence of AKI-Cr the next day.

CONCLUSIONS

Oliguria was significantly associated with the occurrence of new AKI-Cr, however oliguria occurred frequently compared to the small number of patients (~10%) developing AKI-Cr in the ICU, so that most episodes of oliguria were not followed by renal injury. Consequently, the occurrence of short periods (1-6 hr) of oliguria lacked utility in discriminating patients with incipient AKI-Cr (positive likelihood ratios of 2-4, with > 10 considered indicative of a useful screening test). However, oliguria accompanied by hemodynamic compromise or increasing vasopressor dose may represent a clinically useful trigger for other early biomarkers of renal injury.

Risk factors for postoperative complications after open infrarenal abdominal aortic aneurysm repair in Koreans

Purpose

Open infrarenal abdominal aortic aneurysm (AAA) repair is performed without event in most cases. However, some patients suffer major morbidities such as renal failure, myocardial infarction, paraplegia, acute respiratory distress syndrome, or hepatic dysfunction. Predicting what kinds of patient populations are more prone to develop such complications may keep the clinicians more attentive to the patients, possibly leading to better prognoses. In this retrospective study, we searched the incidence of and risk factors for postoperative complications and their predictive equations in 162 patients who underwent open infrarenal AAA repair.

Materials and Methods

Postoperative complications were observed within 30 days. Patient characteristics, types of aneurysm and surgery, and hemodynamic and metabolic variables during the periclamp period were analyzed in relation to postoperative complications using multiple logistic regression analysis.

Results

Postoperative complications involved the cardiac (20%), pulmonary (14%), renal (13%), gastrointestinal (6%), hepatic (3.1%), and neurologic (2.5%) systems, and bleeding occurred in 1.2% of cases. The mortality rate was 5.6%. The risk factors were age [> 67 yrs, odds ratio (OR) 2.6], clamp duration (> 110 min, OR 4.7), volume of blood transfusion (> 1,280 mL, OR 4.4), emergency operation (OR 1.4), and vasopressor infusion during clamp (OR 1.4). The prediction model was: P(x) = exp(α)/[1 + exp(α)] α;-2.2 + 0.9 × age + 1.5 × clamp duration + 1.5 × transfusion + 0.3 × emergency + 0.4 × vasopressor infusion [insert 1 if risk factors exist, otherwise, insert 0 to each variable].

Conclusion

A significant number of complications occurred after infrarenal AAA repair. Therefore, creating a protocol to identify and monitor high risk patients would improve postoperative care.

Innovations in treating aortic diseases: the abdominal aorta

Patients with an abdominal aortic aneurysm (AAA) could benefit from earlier diagnosis to improve long-term outcomes. Candidate serum biomarkers for earlier AAA diagnosis include D-dimer, fibrinogen, low-density lipoprotein, high-density lipoprotein, lipoprotein(a), and the proteolytic enzymes known as matrix metalloproteinases. Furthermore, biomarkers such as brain natriuretic peptide significantly stratify perioperative risk in AAA repair. Statins significantly improve outcomes after AAA repair. They may also significantly slow AAA growth to allow pharmacologic arrest of AAA development. Recent trials have focused attention on fluid management for AAA repair. Although restrictive fluid management may significantly improve clinical outcomes, current evidence does not clearly support crystalloid or colloid for AAA repair. There may be an increased risk of renal dysfunction associated with hetastarch therapy. Endovascular repair has revolutionized the clinical management of AAAs. Recent trials have shown its significant outcome advantages. Furthermore, it is also applicable in high-risk operative cohorts and, in the future, may be suited for earlier AAA repair. This technology continues to advance with the development of branched and fenestrated grafts as well as total percutaneous endovascular AAA repair. Regardless of these advances, the clinical management of endoleaks will remain a major clinical focus. Taken together, these advances in the management of AAAs likely will significantly influence future clinical approaches to this challenging patient cohort.

Anesthesia for Open Abdominal Aortic Aneurysm Repair

Abdominal aortic aneurysms (AAAs) are the 13th leading cause of death in the United States 1 and approximately 40,000 patients undergo elective AAA repair each year.2 With the population aging, this number is expected to increase. Although the use of endovascular AAA repair is becoming more common, open repair, first reported by Dubost et al. in 1951 remains the gold standard.2 This chapter will review the etiology, risk factors, diagnosis, pathophysiology, operative technique, perioperative management, and postoperative complications of patients undergoing open AAA repair.

Preliminary results of a prospective randomized trial of restrictive versus standard fluid regime in elective open abdominal aortic aneurysm repair

BACKGROUND

Open abdominal aortic aneurysm (AAA) repair is associated with a significant morbidity (primarily respiratory and cardiac complications) and an overall mortality rate of 4% to 10%. We tested the hypothesis that perioperative fluid restriction would reduce complications and improve outcome after elective open AAA repair.

METHODS

In a prospective randomized control trial, patients undergoing elective open infra-renal AAA repair were randomized to a "standard" or "restricted" perioperative fluid administration group. Primary outcome measure was rate of major complications (MC) after AAA repair and secondary outcome measures included: Sequential Organ Failure Assessment Score; FiO2/PO2 ratio; Urinary Albumin/Creatinine Ratio; Length-of-stay in, intensive care unit, high dependency unit, in-hospital. This prospective Randomized Controlled Trial was registered in a publicly accessible database and has the following ID number ISRCTN27753612.

RESULTS

Overall 22 patients were randomized, 1 was excluded on a priori criteria, leaving standard group (11) and restricted group (10) for analysis. No significant difference was noted between groups in respect to age, gender, American Society Anesthesiology class, Physiological and Operative Severity Score for the Enumeration of Mortality and Morbidity scores, operation time, and operation blood loss. There were no in-hospital deaths and no 30-day mortality. The cumulative fluid balance on day 5 postoperative was for standard group, 8242 +/- 714 mL, compared with restricted group, 2570 +/- 977 mL, P < 0.01. MC were significantly reduced in the restricted group (n = 10), 1 MC, compared with standard group (n = 11), 14 MC, P < 0.024. Total and postoperative length-of-stay in-hospital was significantly reduced in the restricted group, 9 +/- 1 and 8 +/- 1 days, compared with standard group, 18 +/- 5 and 16 +/- 5 days, P < 0.01 and P < 0.025, respectively.

CONCLUSIONS

Serious complications are common after elective open AAA repair, and we have shown for the first time that a restricted perioperative fluid regimen can prevent MC and significantly reduce overall hospital stay.

Effect of postoperative restrictive fluid therapy in the recovery of patients with abdominal vascular surgery

OBJECTIVE

To compare the outcome of the postoperative administration of a restricted or standard intravenous fluid regimen in patients who underwent elective abdominal vascular surgery. The primary end point was postoperative hospital stay.

DESIGN

Prospective observer-blinded, randomised controlled trial.

MATERIAL AND METHODS

Patients were considered eligible if they underwent transperitoneal aorto-iliac approach with infrarenal graft repair. During the operation and intensive care unit stay, fluids were prescribed by the anaesthetists who were unaware of the details of the study. In the vascular surgical ward, patients in the standard group (SG) received 2500ml of fluids per day, whereas patients in the restricted group (RG) received 1500ml of fluids per day. All the patients were evaluated on an intention-to-treat basis.

RESULTS

Forty patients were randomised to the RG (n=20) or SG (n=20). No significant differences were observed in the recovery of gastrointestinal function. However, the postoperative hospital stay was shorter in the RG (8 days) than in the SG (12 days) (p=0.003).

CONCLUSIONS

The use of a restrictive postoperative fluid protocol significantly reduces the duration of hospital stay in patients who have undergone major elective abdominal vascular surgery.