Factors related to post-operative metabolic acidosis following major abdominal surgery

Effect of isotonic sodium bicarbonate infusion on perioperative acid-base status among patients undergoing emergency laparotomy for perforation peritonitis (ISABEL trial): a randomized controlled trial

PURPOSE

Perioperative metabolic acidosis negatively affects patient outcomes. Perioperative fluid therapy has a clinically significant effect on acid-base balance. This study was conducted to evaluate the effects of isotonic sodium bicarbonate infusion (ISB) versus balanced crystalloid solution (BCS) on perioperative acid-base balance, in terms of postoperative base excess, among patients undergoing emergency laparotomy for perforation peritonitis.

METHODS

This prospective, randomized, single-center, double-blinded study was conducted in a tertiary hospital from October 2021 to November 2022. A total of 90 patients undergoing emergency laparotomy for perforation peritonitis were randomly assigned to receive either isotonic sodium bicarbonate (ISB) or Ringer's Lactate as a balanced crystalloid solution (BCS) for perioperative maintenance fluid therapy. The primary outcome was to compare the base excess (BE) at the end of surgery. The secondary outcomes were to compare the postoperative clinical outcomes, including the requirement of vasopressors, duration of mechanical ventilation, HDU/ICU stay, the incidence of AKI within seven days, the incidence of re-exploration, and in-hospital mortality. Additionally, pH, PaCO2, HCO3, BE, and lactates intraoperatively and up to 24 h postoperatively were also compared.

RESULTS

The median base excess (BE) values at the end of surgery were significantly better in the ISB group - 4.80 [- 6.80, - 4.10] as compared to the BCS group - 7.30 [- 8.50, - 6.30]. The ISB group had a lower incidence of postoperative AKI (9% ISB versus 24% BCS) and requirement of vasopressors (18% ISB versus 44% BCS). However, there was no major difference between the incidence of re-exploration, length of ICU/HDU stay, and in-hospital mortality.

CONCLUSION

Infusing isotonic sodium bicarbonate (ISB) for intraoperative maintenance fluid therapy in patients undergoing emergency laparotomy for perforation peritonitis significantly improves perioperative acid-base balance with better postoperative clinical outcomes compared to a balanced crystalloid solution (BCS).

Association between delta anion gap/delta bicarbonate and outcome of surgical patients admitted to intensive care unit

BACKGROUND

Patients undergoing high-risk surgeries with acid-based disorders are associated with poor outcomes. The screening of mixed acid-based metabolic disorders by calculating delta anion gap (AG)/delta bicarbonate (Bic) has a clinically relevant role in patients with high AG metabolic acidosis (MA), however its utility in individuals facing high-risk surgical procedures remains unclear.

OBJECTIVE

Characterize metabolic acidosis using delta-AG/delta-Bic and its associations in patients undergoing high-risk surgeries with possible outcome-related complications.

DESIGN

Prospective observational multicentric study.

SETTING

Three tertiary hospitals in Brazil.

PATIENTS

Patients undergoing high-risk surgeries, aged 18 years or older, requiring postoperative critical care.

MAIN OUTCOME MEASURES

Patients undergoing high-risk surgeries monitored during the postoperative phase across three distinct intensive care units (ICUs), with assessment encompassing laboratory analyses upon admission and 24 h thereafter. Patients with MA and with elevated AG within 24 h were separated into 3 subgroups: [G1 - delta-AG/delta-Bic < 1.0] MA associated with hyperchloremia; [G2 - delta-AG/delta-Bic between 1.0 and 1.6] MA and no mixed disorders; and [G3 - delta-AG/delta-Bic > 1.6] MA associated with alkalosis. Primary endpoint was 30-day mortality. The secondary endpoints were cardiovascular, respiratory, renal, neurological, coagulation and infective complications.

RESULTS

From the 621 surgical patients admitted to ICU, 421 (51.7%) had any type of acidosis. After 24 h, 140 patients remained with MA with elevated AG (G1: 101, G2: 18, and G3: 21). When compared to patients from subgroups 1 and 3, the subgroup with no mixed disorders 2 showed higher 30-day mortality (adjusted HR = 3.72; 95% CI 1.11-12.89, p = 0.001), cardiovascular complications (p = 0.001), ICU mortality (p = 0.03) and sum of all complications during the ICU period (p = 0.021).

CONCLUSION

In the postoperative time, patients with metabolic acidosis and no mixed disorders present higher ICU-Mortality and higher cardiovascular postoperative complications when compared with patients with combined hyperchloremia or alkalosis. Delta-AG/delta-Bic can be a useful tool to evaluate major clinical outcomes in this population.

Defining Physiological Ketosis Following Very-Low-Calorie Diets

INTRODUCTION

Very low-calorie diets (VLCDs) are used preoperatively in bariatric-metabolic surgery; however, this can lead to physiological ketosis. Euglycemic ketoacidosis is an increasingly recognized complication in diabetic patients on sodium-glucose-cotransporter-2 inhibitors (SGLT2i) undergoing surgery and requires assessment of ketones for diagnosis and monitoring. VLCD induced ketosis may confound monitoring in this group. We aimed to evaluate the influence of VLCD, compared to standard fasting, on perioperative ketone levels and acid-base balance.

MATERIALS AND METHODS

Twenty-seven patients were prospectively recruited to the intervention group and 26 to the control group from two tertiary referral centres in Melbourne, Australia. Intervention group patients were severely obese (body mass index) (BMI) (≥35), undergoing bariatric-metabolic surgery, and prescribed 2 wk of VLCD preoperatively. Control group patients underwent general surgical procedures and prescribed standard procedural fasting only. Patients were excluded if diabetic or prescribed SGLT2i. Ketone and acid-base measurements were taken at regular intervals. Univariate and multivariate regression was utilised with significance defined as P < 0.005.

CLINICALTRIALS

gov ID: NCT05442918.

RESULTS

Patients on VLCD, compared to standard fasting, had an increased median preoperative (0.60 versus 0.21 mmol/L), immediate postoperative (0.99 versus 0.34 mmol/L) and day 1 postoperative (0.69 versus 0.21 mmol/L) ketone level (P < 0.001). Preoperative acid-base balance was normal in both groups, however VLCD patients were found to have a metabolic acidosis immediately postoperatively (pH 7.29 versus pH 7.35) (P = 0.019). Acid-base balance had normalized in VLCD patients on postoperative day 1.

CONCLUSIONS

Preoperative VLCD resulted in increased pre- and postoperative ketone levels with immediate postoperative values consistent with metabolic ketoacidosis. This should be considered particularly when monitoring diabetic patients prescribed SGLT2i.

Metabolic Acidosis Results in Sexually Dimorphic Response in the Heart Tissue

Metabolic acidosis (MA) is a highly prevalent disorder in a significant proportion of the population, resulting from imbalance in blood pH homeostasis. The heart, being an organ with very low regenerative capacity and high metabolic activity, is vulnerable to chronic, although low-grade, MA. To systematically characterize the effect of low-grade MA on the heart, we treated male and female mice with NH4Cl supplementation for 2 weeks and analyzed their blood chemistry and transcriptomic signature of the heart tissue. The reduction of pH and plasma bicarbonate levels without an associated change in anion gap indicated a physiological manifestation of low-grade MA with minimal respiratory compensation. On transcriptomic analysis, we observed changes in cardiac-specific genes with significant gender-based differences due to MA. We found many genes contributing to dilated cardiomyopathy to be altered in males, more than in females, while cardiac contractility and Na/K/ATPase-Src signaling were affected in the opposite way. Our model presents a systems-level understanding of how the cardiovascular tissue is affected by MA. As low-grade MA is a common ailment with many dietary and pharmaceutical interventions, our work presents avenues to limit chronic cardiac damage and disease manifestation, as well as highlighting the sex differences in MA-induced cardiovascular damage.

Clinical impact of lactate on postoperative pancreatic fistula after pancreaticoduodenectomy: A single-center retrospective study of 1,043 patients

BACKGROUND/OBJECTIVES

Several hemodynamic markers have been studied to predict postoperative complication which is a risk factor for poor quality of life and prognosis. The aim of this study was to determine whether postoperative lactate clearance could affect clinical outcome based on complications in one surgical patient group.

METHODS

We retrospectively reviewed data from all patients who underwent pancreaticoduodenectomy (PD) at Samsung Medical Center from January 2015 to December 2019. Differences in baseline characteristics of patients, intraoperative outcome, and postoperative outcome were evaluated according to the presence or absence of clinically relevant postoperative pancreatic fistula (CR-POPF).

RESULTS

Among a total of 1107 patients, 1043 patients were tested for arterial lactate levels immediately after surgery, and the day after surgery. Immediately postoperative hyperlactatemia (lactate ≥2.0 mmol/L) was not related to CR-POPF (P = 0.269). However, immediately postoperative hyperlactatemia with a negative lactic clearance on postoperative day (POD) 1 was related to CR-POPF (P = 0.003). In multivariate analyses, non-pancreatic cancer (hazard ratio (HR): 2.545, P < 0.001), soft pancreatic texture (HR: 1.884, P < 0.001), and postoperative hyperlactatemia with negative lactate clearance on POD 1 (HR: 1.805, P = 0.008) were independent risk factors for CR-POPF.

CONCLUSIONS

Hyperlactatemia with negative lactate clearance after PD, one of the high-risk surgeries requiring postoperative ICU care, is a risk factor for CR-POPF. In case of immediately postoperative hyperlactatemia after PD, lactate clearance with serial lactate level follow-up can be used for achieving the hemodynamic goal to prevent CR-POPF.

Immune, Blood Cell, and Blood Gas Biomarkers of Delirium in Elderly Individuals with Hip Fracture Surgery

BACKGROUND

Postoperative delirium in elderly people with hip fracture is associated with various adverse clinical outcomes. Nevertheless, the pathophysiological processes underpinning delirium have remained elusive.

OBJECTIVES

The aim of this study was to explore the associations between delirium and its features and immune-inflammatory and blood gas biomarkers.

METHODS

In this prospective study, we examined 65 patients who underwent a hip fracture surgery and assessed the Confusion Assessment Method for the Intensive Care Unit, Richmond Agitation-Sedation Scale (RASS), and Delirium Rating Scale Revised-98 (DRS-R-98) before and during 4 days after the surgery. Complete blood count and venous blood gas markers were obtained at the same time points.

RESULTS

Delirium was observed in 19 patients and was accompanied by significantly increased pO2, number of white blood cells, neutrophil percentage, and neutrophil/lymphocyte ratio, and lower mean platelet volume (MPV) after adjusting for age, central nervous system (CNS) disease, blood loss during surgery, sleep disorders, and body mass index. The severity of delirium was associated with lowered number of platelets and MPV. Psychomotor disorders were associated with lower bicarbonate levels. The requirement of physical restraint of the patients was predicted by increased percentages of neutrophils and lymphocytes. Prior CNS disease was together with these biomarkers a significant predictor of delirium and severity of delirium.

CONCLUSION

Delirium and psychomotor disorders following hip fracture and surgery may be caused by immune-inflammatory and oxidative stress pathways probably attributable to an aseptic inflammatory process.

The therapeutic importance of acid-base balance

Baking soda and vinegar have been used as home remedies for generations and today we are only a mouse-click away from claims that baking soda, lemon juice, and apple cider vinegar are miracles cures for everything from cancer to COVID-19. Despite these specious claims, the therapeutic value of controlling acid-base balance is indisputable and is the basis of Food and Drug Administration-approved treatments for constipation, epilepsy, metabolic acidosis, and peptic ulcers. In this narrative review, we present evidence in support of the current and potential therapeutic value of countering local and systemic acid-base imbalances, several of which do in fact involve the administration of baking soda (sodium bicarbonate). Furthermore, we discuss the side effects of pharmaceuticals on acid-base balance as well as the influence of acid-base status on the pharmacokinetic properties of drugs. Our review considers all major organ systems as well as information relevant to several clinical specialties such as anesthesiology, infectious disease, oncology, dentistry, and surgery.

Increase in serum chloride and chloride exposure are associated with acute kidney injury in moderately severe and severe acute pancreatitis patients

OBJECTIVE

We aimed to evaluate whether early (first 48 h) hyperchloremia and/or the change of serum chloride concentration are associated with acute kidney injury (AKI) in patients with moderately severe and severe acute pancreatitis (MSAP and SAP).

METHODS

We retrospectively collected the data of patients with a primary diagnosis of MSAP or SAP from a tertiary center between January 2014 and June 2017. Consecutive chloride levels within the first 48 h after admission were retrieved for further calculation. Logistic regression analysis and receiving operating characteristic (ROC) curve were used to assess the relationship between hyperchloremia and AKI.

RESULTS

145 patients were enrolled for analysis, of whom 33.5% (47/145) developed hyperchloremia during the observation period. The incidence of AKI was significantly higher in the hyperchloremia group (40.4% vs 7.1%; p < 0.001). On multivariate analysis, the increase in serum chloride (Δ[Cl-]) was independently associated with AKI [OR = 1.32 (1.00-1.74)], as was chloride exposure [OR = 1.01 (1.00-1.02)], and these associations were found to be stronger in patients identified as predicted SAP (PSAP). Moreover, even in patients without hyperchloremia, increase in serum chloride (Δ[Cl-]) was still associated with AKI [OR = 1.65 (1.18-2.32)]. Area under the curve of the ROC curve (AUCROC) analysis found that Δ[Cl-] is a good predictor of AKI with an optimal cutoff point at 3.5 mmol/L, showing an AUCROC of 0.81.

CONCLUSION

Hyperchloremia is common in patients with AP and Δ[Cl^-] and chloride exposure during the first 48 h were independent risk factors for AKI in MSAP and SAP patients.

Blood cardioplegia benefits only patients with a long cross-clamp time

INTRODUCTION

A clear advantage of blood versus crystalloid cardioplegia has not yet been observed in smaller population studies. The purpose of this article was to further investigate the clinical outcomes of blood versus crystalloid cardioplegia in a large propensity-matched cohort of patients who underwent cardiac surgery.

METHODS

The study was a single-centre study. Data was withdrawn from the Western Denmark Heart Registry, which comprises a perfusion section for each procedure. A total of 4,852 patients were propensity matched into crystalloid (CC) vs blood cardioplegia (BC) groups. The primary end points were creatinine kinase-MB (CKMB) elevation, acute myocardial infarction (AMI), stroke, dialysis, coronary angiography (CAG) and mortality (30 days and 6 months).

RESULTS

We found lower odds ratio in 30-day mortality in the BC group (OR 0.21; CI 0.06-0.68), but no difference in overall 6-month mortality. There was no difference in CKMB elevation, AMI, dialysis or stroke. Several end points were further analysed for different cross-clamp times. In the CC group, ventilation time above 600 minutes was seen more often in almost all cross-clamp time intervals (23.5 % vs 12.2 %; p<0.0001; χ²-test) and 6-month mortality was significantly higher when the cross-clamp time exceeded 210 minutes (64.3 vs 23.8; p=0.018; χ²-test).

CONCLUSIONS

We did not find clear evidence of superiority of either type in the uncomplicated patient. When prolonged cross-clamp time or postoperative ventilation is expected, this study indicates that blood cardioplegia might be preferable.

Perioperative metabolic acidosis: The Bradford Anaesthetic Department Acidosis Study

Metabolic acidosis is considered deleterious but is common in post-surgical patients admitted to intensive care unit. We evaluated the prevalence and time course of metabolic acidosis in elective major surgery, and generated hypotheses about causes, by hourly arterial blood sampling in 92 patients. Metabolic acidosis began before incision and most had occurred by the next hour. Seventy-eight per cent of patients had a significant metabolic acidosis post-operatively. Two overlapping phases were observed. The early phase started before incision, characterised by a rising chloride and falling anion gap, unrelated to saline use. The late phase was partly associated with lactate, related to surgery type, and early fluids appeared protective. There was a trend towards longer intensive care unit (+1.3 days) and hospital (+3.2 days) stay with metabolic acidosis. This is the first large study of the evolution of this common finding, demonstrating a pre-incision component. The early phase appears unavoidable or unpredictable, but the late phase might be modified by early fluid administration. It remains unclear whether acidosis of this type should be avoided.

Bright light and oxygen therapies decrease delirium risk in critically ill surgical patients by targeting sleep and acid-base disturbances

This study examined the effects of bright light therapy (BLT) on the incidence of delirium in post-operative patients admitted to a surgical intensive care unit (SICU) and delineates risk and protective factors. We included 62 patients in a single-blind, randomized controlled study. The intervention group was treated with care as usual plus BLT for three consecutive days. Delirium was diagnosed by DSM-5 criteria with the Confusion Assessment Method-Intensive Care Unit (CAM-ICU). Risk factors for delirium were measured, including the APACHE II score, Insomnia Severity Index (ISI), as well as hematocrit and bicarbonate levels. Results were adjusted for treatment with nasal cannula oxygen and medications. Thirteen patients developed delirium within the three days following surgery. Generalized estimating equations analysis showed a significant preventive effect of BLT on delirium, which was independent of risk or treatment factors. Higher APACHE-II and ISI scores, lower hematocrit and lower bicarbonate levels increased the risk of developing delirium. BLT plus nasal cannula oxygen significantly reduced the likelihood of delirium. BLT significantly lowered ISI scores, while nasal cannula oxygen significantly enhanced bicarbonate levels. The results indicate that BLT and supplementary oxygen therapy may protect against delirium by targeting sleep-wake and deficits in the bicarbonate buffer system.

Recommendations for perioperative management of lung cancer patients with comorbidities

Objectives

To improve surgical outcomes, clinicians must provide optimal perioperative care for comorbidities identified as significant factors in risk models for patients undergoing lung cancer surgery.

Methods

We reviewed trends in perioperative care for idiopathic pulmonary fibrosis, cardiovascular diseases, and end-stage renal diseases in patients undergoing lung cancer surgery, as large clinical databases indicate that these comorbidities are significant risk factors for lung cancer surgery. Articles identified by keyword searches were included in the analysis.

Results

Significant predictive factors for acute exacerbation of idiopathic pulmonary fibrosis were identified. However, no effective perioperative care was identified for prevention of acute exacerbation of interstitial pneumonia. The timing of coronary revascularization and antithrombotic management for cardiovascular diseases are subjects of ongoing research, and acid–base balance is essential in the management of hemodialysis patients with end-stage renal diseases.

Conclusions

To improve surgical outcomes for lung cancer patients, future studies should continue to study optimal perioperative management of comorbidities.

Fluid management in living donor hepatectomy: Recent issues and perspectives

The importance of the safety of healthy living liver donors is widely recognized during donor hepatectomy which is associated with blood loss, transfusion, and subsequent post-operative morbidity. Although the low central venous pressure (CVP) technique can still be effective, it may not be advantageous concerning the safety of healthy donors undergoing hepatectomy. Emerging evidence suggests that stroke volume variation (SVV), a simple and useful index for fluid responsiveness and preload status in various clinical situations, can be applied as a guide for fluid management to reduce blood loss during living donor hepatectomy. Synthetic colloid solutions are also associated with serious adverse events such as the use of renal replacement therapy and transfusion in critically ill or septic patients. However, it is uncertain whether the intra-operative use of colloid solution is associated with similarly adverse effects in patients undergoing living donor hepatectomy. In this review article we discuss the recent issues regarding the low CVP technique and the high SVV method, i.e., maintaining 10%-20% of SVV, for fluid management in order to reduce blood loss during living donor hepatectomy. In addition, we briefly discuss the effects of intra-operative colloid or crystalloid administration for surgical rather than septic or critically ill patients.