Association between preoperative hydration status and acute kidney injury in patients managed surgically for kidney tumours

Preoperative Nil Per Os Duration Predicts Mortality and Ambulation Following Below-Knee Amputation

BACKGROUND

Routine use of nil per os (NPO) prior to procedures has been associated with dehydration and malnutrition leading to patient discomfort. We aim to examine how duration of NPO status affects postoperative outcomes in patients undergoing elective below-knee amputation (BKA).

METHODS

We performed a retrospective chart review of 92 patients who underwent elective BKA between 2014-2022 for noninfectious indications. We performed statistical analysis using Chi-square tests, t-tests, and linear/logistic regression with odds ratio using P < .05 as our significance level.

RESULTS

The mean age was 48.0 ± 16.7 years, and there were 64 (70%) male patients and 41 (45%) Black patients. Mean NPO duration was 12.9 ± 4.7 hours. Patients with longer NPO duration were associated with increased rates of postoperative stroke (P = .03). Patients with shorter NPO duration had significantly lower mean BUN on postoperative day (POD) 1 (14.5, P < .001) and POD 3 (14.1, P < .001) compared to preoperative mean BUN (16.8), however this normalized by POD 7 (19.2, P = .26). There were no changes in postoperative renal function based on baseline kidney disease status or associated with longer NPO duration. Shorter NPO duration was a predictor of increased likelihood of 1-year follow-up (OR: 2.9 [1.24-6.79], P = .01), independent ambulation (OR: 2.7 [1.03-7.34], P = .04), and decreased mortality (OR: .11 [.013-.91], P = .04).

CONCLUSION

While NPO duration does not appear to result in postoperative renal dysfunction, prolonged NPO duration predicts worse rates of follow-up, ambulation, and survival and is associated with increased stroke rates.

Preoperative fasting and the risk of pulmonary aspiration-a narrative review of historical concepts, physiological effects, and new perspectives

In the early days of anaesthesia, the fasting period for liquids was kept short. By the mid-20th century 'nil by mouth after midnight' had become routine as the principles of the management of 'full stomach' emergencies were extended to include elective healthy patients. Back then, no distinction was made between the withholding of liquids and solids. Towards the end of the last century, recommendations of professional anaesthesiology bodies began to reduce the fasting time of clear liquids to 2 h. This reduction in fasting time was based on the understanding that gastric emptying of clear liquids is rapid, exponential, and proportional to the current filling state of the stomach. Furthermore, there was no evidence of a link between drinking clear liquids and the risk of aspiration. Indeed, most instances of aspiration are caused by failure to identify aspiration risk factors and adjust the anaesthetic technique accordingly. In contrast, long periods of liquid withdrawal cause discomfort and may also lead to serious postoperative complications. Despite this, more than two decades after the introduction of the 2 h limit, patients still fast for a median of up to 12 h before anaesthesia, mainly because of organisational issues. Therefore, some hospitals have decided to allow patients to drink clear liquids within 2 h of induction of anaesthesia. Well-designed clinical trials should investigate whether these concepts are safe in patients scheduled for anaesthesia or procedural sedation, focusing on both aspiration risk and complications of prolonged fasting.

Association of intraoperative hypotension and severe postoperative complications during non-cardiac surgery in adult patients: A systematic review and meta-analysis

Background

Intraoperative hypotension (IOH) is a common side effect of non-cardiac surgery that might induce poor postoperative outcomes. The relationship between the IOH and severe postoperative complications is still unclear. Thus, we summarized the existing literature to evaluate whether IOH contributes to developing severe postoperative complications during non-cardiac surgery.

Methods

We conducted a comprehensive search of PubMed, Embase, Cochrane Library, Web of Science, and the CBM from inception to 15 September 2022. The primary outcomes were 30-day mortality, acute kidney injury (AKI), major adverse cardiac events (myocardial injury or myocardial infarction), postoperative cognitive dysfunction (POCD), and postoperative delirium (POD). Secondary outcomes included surgical-site infection (SSI), stroke, and 1-year mortality.

Results

72 studies (3 randomized; 69 non-randomized) were included in this study. Low-quality evidence showed IOH resulted in an increased risk of 30-day mortality (OR, 1.85; 95% CI, 1.30-2.64; P < .001), AKI (OR, 2.69; 95% CI, 2.15-3.37; P < .001), and stroke (OR, 1.33; 95% CI, 1.21-1.46; P < .001) after non-cardiac surgery than non-IOH. Very low-quality evidence showed IOH was associated with a higher risk of myocardial injury (OR, 2.00; 95% CI, 1.17-3.43; P = .01), myocardial infarction (OR, 2.11; 95% CI, 1.41-3.16; P < .001), and POD (OR, 2.27; 95% CI, 1.53-3.38; P < .001). Very low-quality evidence showed IOH have a similar incidence of POCD (OR, 2.82; 95% CI, 0.83-9.50; P = .10) and 1-year-mortality (OR, 1.66; 95% CI, 0.65-4.20; P = .29) compared with non-IOH in non-cardiac surgery.

Conclusion

Our results suggest IOH was associated with an increased risk of severe postoperative complications after non-cardiac surgery than non-IOH. IOH is a potentially avoidable hazard that should be closely monitored during non-cardiac surgery.

The association between modifiable perioperative parameters and renal function after nephrectomy

OBJECTIVE

To evaluate the association between intraoperative anaesthetic parameters, primarily intraoperative hypotension, and postoperative renal function in patients undergoing nephrectomy.

PATIENTS AND METHODS

We reviewed data from 3240 consecutive patients who underwent nephrectomy between 2010 and 2018. Anaesthetic parameters evaluated included duration of hypotension, tachycardia, hypothermia, volatile anaesthetic use and mean arterial pressure in the post-anaesthesia care unit. Outcomes included acute kidney injury (AKI) and estimated glomerular filtration rate (eGFR) within the first year after nephrectomy. Associations between anaesthetic parameters and outcomes were evaluated with multivariable logistic regression and generalised estimating equation, respectively, adjusted for predictors of renal function after nephrectomy.

RESULTS

Before nephrectomy, 677 (21%) patients had moderate-severe chronic kidney disease. A quarter of patients (n = 809) had postoperative AKI and 35% (n = 746) had Stage ≥3 chronic kidney disease 12-months after surgery. Only 12% of patients (n = 386) had >5 min of intraoperative hypotension. While not statistically significant, longer duration of intraoperative hypotension was associated with slightly higher rates of AKI (odds ratio [OR] per 10-min 1.14, 95% confidence interval [CI] 0.98, 1.32). Prolonged hypothermia was associated with increased rate of AKI (OR per 10-min 1.02, 95% CI 1.00, 1.04), and decreased eGFR (change in eGFR per 10-min -0.19, 95% CI -0.27, -0.12); however, these results have limited clinical significance.

CONCLUSIONS

Under current practice, intraoperative anaesthetic parameters are tightly maintained, restricting the significance of their effect on postoperative renal function. Future studies should evaluate whether haemodynamic parameters during the early postoperative period, when they are monitored less frequently, are associated with renal functional outcome.

Risk of Postoperative Renal Failure in Radical Nephrectomy and Nephroureterectomy: A Validated Risk Prediction Model

INTRODUCTION

The study aimed to construct and validate a risk prediction model for incidence of postoperative renal failure (PORF) following radical nephrectomy and nephroureterectomy.

METHODS

The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database years 2005-2014 were used for the derivation cohort. A stepwise multivariate logistic regression analysis was conducted, and the final model was validated with an independent cohort from the ACS-NSQIP database years 2015-2017.

RESULTS

In cohort of 14,519 patients, 296 (2.0%) developed PORF. The final 9-factor model included age, gender, diabetes, hypertension, BMI, preoperative creatinine, hematocrit, platelet count, and surgical approach. Model receiver-operator curve analysis provided a C-statistic of 0.79 (0.77, 0.82; p < 0.001), and overall calibration testing R2 was 0.99. Model performance in the validation cohort provided a C-statistic of 0.79 (0.76, 0.81; p < 0.001).

CONCLUSION

PORF is a known risk factor for chronic kidney disease and cardiovascular morbidity, and is a common occurrence after unilateral kidney removal. The authors propose a robust and validated risk prediction model to aid in identification of high-risk patients and optimization of perioperative care.

Preoperative Concentrated Urine Increases the Incidence of Plasma Creatinine Elevation After Major Surgery

Background: Postoperative elevation of plasma creatinine is a frequent complication to major surgery. A rise by 50% fulfills the criterion for Acute Kidney Injury. We studied the relationship between concentrated urine before surgery, which is usually a sign of chronically low intake of water, and the perioperative change in plasma creatinine.

Methods: The creatinine concentration was measured in plasma and urine just before and at 6 h, 1 day, and 2 days after major abdominal surgery in a consecutive series of 181 patients. Receiver operating curve analysis was used to find the optimal cut-off to separate concentrated from diluted urine.

Results: Urine creatinine of 11.3 mmol/L before the surgery started was exceeded in one third of the patients and associated with greater increase in plasma creatinine at 6 h (median 21 vs. 10%) and at 1 day postoperatively (21 vs. 7%; P < 0.0001). Elevation of plasma creatinine of >25% occurred in 41% and 19% in those with high and low urine creatinine, respectively (P < 0.001) and an increase by >50% in 16% and 10% (P = 0.27). Patients with high urine creatinine before surgery failed to further concentrate their urine during the perioperative period, which is normally associated with intensified renal fluid conservation.

Conclusion: High urinary concentration of creatinine before surgery should be considered as a risk factor for postoperative elevation of plasma creatinine. The mechanism is probably that the renal threshold is then more easily reached.

[Preoperative fluid fasting : Establishment of a liberal fluid regimen using fasting cards]

BACKGROUND

Preoperative fasting times for clear liquids surpass by far the recommendations of the specialist societies. The aim of this study was to introduce a liberal regimen for preoperative fasting of clear liquids using fasting cards as a training tool and to evaluate the implementation.

MATERIAL AND METHODS

We developed a liberalized regimen of preoperative clear fluid fasting times, which allows patients to drink water, apple juice, tea and coffee until being called to the operating theatre. Each patient receives a bed-side fasting card with written information specifying fasting times for solid food and liquids. Patients who are allowed to drink water, apple juice, tea and coffee until the call to the operating theatre receive a blue fasting card. Patients with coexisting diseases or conditions that can affect gastric emptying or who need longer fasting times because of the surgical procedure get a yellow fasting card on which fasting times for fluids and solids can be documented individually. Patients who need to be nil per os (for example patients with ileus or bowel obstruction, emergency care) receive a red fasting card. On the back of the card the information is written in English, Turkish, Russian and Arabic. After a period of 8 months all surgical ward managers were asked to complete a questionnaire to assess the implementation of the new fasting regimen.

RESULTS

The response rate of the questionnaire was 100%. Without exception all interviewees would recommend the use of our liberalized fasting regimen. Almost all would also support the implementation of fasting cards. Out of 11 wards 9 found that patients were more relaxed and asked for intravenous fluids less often while waiting for surgery. The multilingual nature of the cards makes it easier to deal with patients who do not speak German. All ward managers consistently approved the new regimen in the event they themselves would need an operation. In order to make the fasting cards also usable in the future for rescue centers and functional units, such as endoscopy, echo or cardiac catheters, the reasons for fasting on the blue and yellow cards have been extended to operation or examination and on the red card to illness, operation or upcoming examination.

CONCLUSION

Patients should be allowed to drink water and hypotonic clear fluids until shortly before an operation to avoid complications of overly long fasting times. Fasting cards help to implement this by providing easy to understand information for patients and healthcare workers. This concept should be clearly structured, transparent for everyone, written down and brought to the attention of the patient without a language barrier.

[Comments on the updated German S3 guidelines on intravascular volume therapy in adults]

The German S3 guidelines on intravascular volume therapy in adults were updated in September 2020. Based on updated evidence recommendations for the diagnosis of isotonic dehydration and for fluid therapy with crystalloids and colloids in peri-interventional and intensive care medicine were proposed.

Association of intraoperative hypotension with postoperative morbidity and mortality: systematic review and meta-analysis

Background

Intraoperative hypotension, with varying definitions in literature, may be associated with postoperative complications. The aim of this meta-analysis was to assess the association of intraoperative hypotension with postoperative morbidity and mortality.

Methods

MEDLINE, Embase and Cochrane databases were searched for studies published between January 1990 and August 2018. The primary endpoints were postoperative overall morbidity and mortality. Secondary endpoints were postoperative cardiac outcomes, acute kidney injury, stroke, delirium, surgical outcomes and combined outcomes. Subgroup analyses, sensitivity analyses and a meta-regression were performed to test the robustness of the results and to explore heterogeneity.

Results

The search identified 2931 studies, of which 29 were included in the meta-analysis, consisting of 130 862 patients. Intraoperative hypotension was associated with an increased risk of morbidity (odds ratio (OR) 2.08, 95 per cent confidence interval 1.56 to 2.77) and mortality (OR 1.94, 1.32 to 2.84). In the secondary analyses, intraoperative hypotension was associated with cardiac complications (OR 2.44, 1.52 to 3.93) and acute kidney injury (OR 2.69, 1.31 to 5.55). Overall heterogeneity was high, with an I² value of 88 per cent. When hypotension severity, outcome severity and study population variables were added to the meta-regression, heterogeneity was reduced to 50 per cent.

Conclusion

Intraoperative hypotension during non-cardiac surgery is associated with postoperative cardiac and renal morbidity, and mortality. A universally accepted standard definition of hypotension would facilitate further research into this topic.

Acute Kidney Injury in Oncology Patients

With rapid progress in cancer diagnosis and treatment in the last two decades, outcomes in oncological patients have improved significantly. However, the incidence of acute kidney injury (AKI) in this population has also increased significantly. AKI complicates many aspects of patients' care and adversely affects their prognoses; thus, accurately diagnosing the risk factors for AKI ensures appropriate management. AKI may be caused by pre-renal, intrinsic renal, and post-renal reasons, as well as for combined reasons. This review summarizes the potential etiologies of AKI according to the three classifications. For each underlying cause of AKI, the cancer itself and/or cancer treatment may contribute to a patient developing AKI. Therefore, we present disease- and treatment-related factors for each cause category, with special focus on immune checkpoint inhibitors, which are being used increasingly more often. It is important for nephrology services to be knowledgeable to provide the best level of care.

Volume kinetic analysis of fluid retention after induction of general anesthesia

Background

Induction of general anesthesia increases the hemodilution resulting from infusion of crystalloid fluid, which is believed to be due to slower distribution caused by arterial hypotension. When normal distribution returns is not known.

Methods

An intravenous infusion of 25 mL kg^− 1 of Ringer’s lactate was infused over 30 min to 25 volunteers just after induction of general anesthesia for open abdominal hysterectomy. A two-volume model was fitted to the repeated measurements of the blood hemoglobin concentration and the urinary excretion using mixed-effects modelling software. Individual-specific covariates were added in sequence.

Results

Distribution of infused fluid was interrupted during the first 20 min of the infusions. During this time 16.6 mL kg^− 1 of lactated Ringer’s had been infused, of which virtually all remained in the circulating blood. Thereafter, the fluid kinetics was similar to that previously been found in awake volunteers except for the elimination rate constant (k₁₀), which remained to be very low (0.86 × 10^− 3 min^− 1). Redistribution of infused fluid from the interstitium to the plasma occurred faster (higher k₂₁) when the arterial pressure was low. No covariance was found between the fixed parameters and preoperatively concentrated urine, the use of sevoflurane or propofol to maintain the anesthesia, or the plasma concentrations of two degradation products of the endothelial glycocalyx, syndecan-1 and heparan sulfate.

Conclusions

Induction of general anesthesia interrupted the distribution of lactated Ringer’s solution up to when 16.6 mL kg^− 1 of crystalloid fluid had been infused. Plasma volume expansion during this period of time was pronounced.

Trial registration

Controlled-trials.com (ISRCTN81005631) on May 17, 2016 (retrospectively registered).