The riddle of hyperlactatemia

Direct assessment of microcirculation in shock: a randomized-controlled multicenter study

PURPOSE

Shock is a life-threatening condition characterized by substantial alterations in the microcirculation. This study tests the hypothesis that considering sublingual microcirculatory perfusion variables in the therapeutic management reduces 30-day mortality in patients admitted to the intensive care unit (ICU) with shock.

METHODS

This randomized, prospective clinical multicenter trial-recruited patients with an arterial lactate value above two mmol/L, requiring vasopressors despite adequate fluid resuscitation, regardless of the cause of shock. All patients received sequential sublingual measurements using a sidestream-dark field (SDF) video microscope at admission to the intensive care unit (± 4 h) and 24 (± 4) hours later that was performed blindly to the treatment team. Patients were randomized to usual routine or to integrating sublingual microcirculatory perfusion variables in the therapy plan. The primary endpoint was 30-day mortality, secondary endpoints were length of stay on the ICU and the hospital, and 6-months mortality.

RESULTS

Overall, we included 141 patients with cardiogenic (n = 77), post cardiac surgery (n = 27), or septic shock (n = 22). 69 patients were randomized to the intervention and 72 to routine care. No serious adverse events (SAEs) occurred. In the interventional group, significantly more patients received an adjustment (increase or decrease) in vasoactive drugs or fluids (66.7% vs. 41.8%, p = 0.009) within the next hour. Microcirculatory values 24 h after admission and 30-day mortality did not differ [crude: 32 (47.1%) patients versus 25 (34.7%), relative risk (RR) 1.39 (0.91-1.97); Cox-regression: hazard ratio (HR) 1.54 (95% confidence interval (CI) 0.90-2.66, p = 0.118)].

CONCLUSION

Integrating sublingual microcirculatory perfusion variables in the therapy plan resulted in treatment changes that do not improve survival at all.

Mortality and prognostic factors in connective tissue disease-associated pulmonary arterial hypertension patients complicated with right heart failure

OBJECTIVE

To identify predictive factors associated with mortality in connective tissue disease-associated pulmonary arterial hypertension (CTD-PAH) patients who were complicated with right heart failure (RHF).

METHODS

In this single-center retrospective study, baseline demographics, clinical features, laboratory results, and hemodynamic assessments were collected. Kaplan-Meier analysis was applied to analyze all-cause mortality. Univariate and forward stepwise multivariate Cox proportional regression analyses were performed to identify independent predictors of mortality.

RESULTS

A total of 51 right heart catheterization-confirmed CTD-PAH patients complicated with RHF were consecutively enrolled in this study from 2012 to 2022. Forty-eight (94%) enrolled patients were female and the mean age was 36.0 ± 11.8 years. Thirty-two (61.5%) were systemic lupus erythematosus-PAH and 33%/67% showed World Health Organization functional class III/IV, respectively. Twenty-five (49%) of those patients died and Kaplan-Meier analysis showed the overall 1-, 3-, and 5-week survival rates from the time of hospitalization as 86.28%, 60.78%, and 56.86%, respectively. RHF in CTD-PAH patients mainly resulted from progression of PAH (n = 19) and infection (n = 5), which also contributed to the leading causes of death. Statistical analysis between survivors and non-survivors showed that death from RHF was associated with higher levels of urea (9.66 vs 6.34 mmol/L, P = 0.002), lactate (cLac: 2.65 vs 1.9 mmol/L, P = 0.006), total bilirubin (23.1 vs 16.9 μmol/L, P = 0.018) and direct bilirubin (10.5 vs 6.5 μmol/L, P = 0.004), but with lower levels of hematocrit (33.7 vs 39, P = 0.004), cNa+ (131 vs 136 mmol/L, P = 0.003). Univariate and forward stepwise multivariate Cox proportional regression analyses indicated that the level of cLac (hazards ratio:1.297; 95% CI: 1.076-1.564; P = 0.006) was an independent risk factor for mortality.

CONCLUSION

The short-term prognosis of CTD-PAH complicated with RHF was very poor, and hyperlactic acidemia (cLac > 2.85 mmoL/L) was an independent predicting factor for mortality of CTD-PAH patients complicated with RHF.

Pharmacological treatment of cardiogenic shock - A state of the art review

Cardiogenic shock is a clinical syndrome of impaired tissue perfusion caused by primary cardiac dysfunction and inadequate cardiac output. It represents one of the most lethal clinical conditions in intensive care medicine with mortality >40%. Management of different clinical presentations of cardiogenic shock includes guidance of cardiac preload, afterload, heart rate and contractility by differential pharmacological modulation of volume, systemic and pulmonary vascular resistance and cardiac output besides reversing the triggering cause. Data from large registries and randomized controlled trials on optimal diagnostic guidance as well as choice of pharmacological agents has accrued significantly in recent years. This state-of-the-art review summarizes the basic concepts of cardiogenic shock, the diagnostic work-up and currently available evidence and guideline recommendations on pharmacological treatment of cardiogenic shock.

Development and validation of a nomogram model for early postoperative hyperlactatemia in patients undergoing cardiac surgery

Background

Postoperative hyperlactatemia (POHL) is common in patients undergoing cardiac surgery, associated with adverse outcomes. The aim of this study was to identify predictors for POHL after cardiac surgery and to develop and validate a predictive model.

Methods

Adult patients who underwent open heart surgery at our institution between 2016 and 2019 were retrospectively included. The patients were randomly divided into training and validation groups at a 2:1 ratio. Multivariate logistic regression was performed to identify independent predictors for POHL in the training set. A nomogram was then constructed and was validated in the validation set.

Results

POHL developed in 713 of the 5,323 patients (13.4%). The mortality rate was higher in patients with POHL compared with patients without that (9.5% vs. 2.1%, P<0.001). Age, white blood cell (WBC) count, left ventricular ejection fraction, renal insufficiency, cardiac surgery history, red blood cell (RBC) transfusion, and cardiopulmonary bypass (CPB) time were identified as independent risk factors. The nomogram based on these predictors indicated good discrimination in both the training (c-index: 0.787) and validation (c-index: 0.820) sets. The calibration was reasonable by both visual inspection and goodness-of-fit test. The decision and clinical impact curves demonstrated good clinical utility.

Conclusions

We identified 7 independent risk factors and derived a prediction model for POHL in patients undergoing cardiac surgery. The model may contribute significantly to early risk assessment and clinical intervention.

Risk Factors and Outcomes for Postoperative Ileus After Small Intestinal Fistula Excision in Patients With Diffuse Extensive Abdominal Adhesions

Purpose: The study aimed to investigate the risk factors for postoperative ileus (POI) after small intestinal fistula excision (SIFE) in patients with diffuse extensive abdominal adhesions. Methods: From October 2010 to December 2019, we enrolled patients who underwent SIFE and had diffuse extensive abdominal adhesions. Patients were divided into the POI group and the non-POI group according to its occurrence. We then investigated and analyzed the clinical characteristics of both groups. Result: A total of 247 patients were enrolled into the study. There were 100 patients in the POI group, and 147 patients in the non-POI group. A multi-variable logistic regression analysis revealed that blood loss during SIFE (OR = 1.001; 95% CI: 1.000-1.259; P = 0.012), postoperative lactate(OR = 1.212; 95% CI: 1.001-1.304; P = 0.015), grade V abdominal adhesions (OR = 2.518; 95% CI: 1.814-3.44; P = 0.024), and time for recovery of lactate <2 mmol/L (OR = 2.079; 95% CI: 1.599-3.616; P = 0.026) were associated with POI. Moreover, POI was also associated with prolonged postoperative stay in the hospital (HR = 3.291; 95% CI: 2.511-4.172; P = 0.014). Conclusion: Blood loss during operation, grade V abdominal adhesions, positive fluid balance within 48 h of operation, and time for recovery of lactate were the risk factors for POI after SIFE in patients with diffuse extensive abdominal adhesions.

Failure of Lactate Clearance Predicts the Outcome of Critically Ill Septic Patients

Purpose: Early lactate clearance is an important parameter for prognosis assessment and therapy control in sepsis. Patients with a lactate clearance >0% might differ from patients with an inferior clearance in terms of intensive care management and outcomes. This study analyzes a large collective with regards to baseline risk distribution and outcomes. Methods: In total, 3299 patients were included in this analysis, consisting of 1528 (46%) ≤0% and 1771 (54%) >0% patients. The primary endpoint was intensive care unit (ICU) mortality. Multilevel logistic regression analyses were used to compare both groups: A baseline model (model 1) with lactate clearance as a fixed effect and ICU as a random effect was installed. For model 2, patient characteristics (model 2) were included. For model 3, intensive care treatment (mechanical ventilation and vasopressors) was added to the model. Models 1 and 2 were used to evaluate the primary and secondary outcomes, respectively. Model 3 was only used to evaluate the primary outcomes. Adjusted odds ratios (aORs) with respective 95% confidence intervals (CI) were calculated. Results: The cohorts had no relevant differences regarding the gender, BMI, age, heart rate, body temperature, and baseline lactate. Neither the primary infection focuses nor the ethnic background differed between both groups. In both groups, the most common infection sites were of pulmonary origin, the urinary tract, and the gastrointestinal tract. Patients with lactate clearance >0% evidenced lower sepsis-related organ failure assessment (SOFA) scores (7 ± 6 versus 9 ± 6; p < 0.001) and creatinine (1.53 ± 1.49 versus 1.80 ± 1.67; p < 0.001). The ICU mortality differed significantly (14% versus 32%), and remained this way after multivariable adjustment for patient characteristics and intensive care treatment (aOR 0.43 95% CI 0.36–0.53; p < 0.001). In the additional sensitivity analysis, the lack of lactate clearance was associated with a worse prognosis in each subgroup. Conclusion: In this large collective of septic patients, the 6 h lactate clearance is an independent method for outcome prediction.

[Evaluation of the microcirculation in critically ill patients : Relevance, practical possibilities and scientific evidence]

Für die Aufrechterhaltung der Organdurchblutung ist eine intakte Makro- und Mikrozirkulation essentiell. Sowohl das wachsende Verständnis um die Bedeutung der Mikrozirkulation im Organversagen als auch die Möglichkeit, diese zu visualisieren, lenken die Aufmerksamkeit der Intensivmedizin auf die mikrovaskuläre Endstrombahn. Als Surrogat-Parameter sind die Rekapillarisierungszeit, der „mottling score“ und die Messung des Serum-Laktats bereits lange in der klinischen Praxis etabliert. Neuere Studien messen der Echtzeit-Darstellung der sublingualen Mikrozirkulation mittels Intravital-Videomikroskopie eine immer größere Bedeutung bei. Verschiedene Studien unterstreichen hierbei die Mikrozirkulation als prognostischen Parameter. Darüber hinaus ermöglicht die Erhebung von objektivierbaren Messwerten, diese in der Zukunft zur individuellen Therapiesteuerung weitergehend zu untersuchen.

Laboratory diagnostic approaches in metabolic disorders

The diagnosis of inborn errors of metabolism (IEM) takes many forms. Due to the implementation and advances in newborn screening (NBS), the diagnosis of many IEM has become relatively easy utilizing laboratory biomarkers. For the majority of IEM, early diagnosis prevents the onset of severe clinical symptoms, thus reducing morbidity and mortality. However, due to molecular, biochemical, and clinical variability of IEM, not all disorders included in NBS programs will be detected and diagnosed by screening alone. This article provides a general overview and simplified guidelines for the diagnosis of IEM in patients with and without an acute metabolic decompensation, with early or late onset of clinical symptoms. The proper use of routine laboratory results in the initial patient assessment is also discussed, which can help guide efficient ordering of specialized laboratory tests to confirm a potential diagnosis and initiate treatment as soon as possible.

Acidic sweep gas with carbonic anhydrase coated hollow fiber membranes synergistically accelerates CO2 removal from blood

The use of extracorporeal carbon dioxide removal (ECCO2R) is well established as a therapy for patients suffering from acute respiratory failure. Development of next generation low blood flow (<500 mL/min) ECCO2R devices necessitates more efficient gas exchange devices. Since over 90% of blood CO2 is transported as bicarbonate (HCO3(-)), we previously reported development of a carbonic anhydrase (CA) immobilized bioactive hollow fiber membrane (HFM) which significantly accelerates CO2 removal from blood in model gas exchange devices by converting bicarbonate to CO2 directly at the HFM surface. This present study tested the hypothesis that dilute sulfur dioxide (SO2) in oxygen sweep gas could further increase CO2 removal by creating an acidic microenvironment within the diffusional boundary layer adjacent to the HFM surface, facilitating dehydration of bicarbonate to CO2. CA was covalently immobilized onto poly (methyl pentene) (PMP) HFMs through glutaraldehyde activated chitosan spacers, potted in model gas exchange devices (0.0151 m(2)) and tested for CO2 removal rate with oxygen (O2) sweep gas and a 2.2% SO2 in oxygen sweep gas mixture. Using pure O2 sweep gas, CA-PMP increased CO2 removal by 31% (258 mL/min/m(2)) compared to PMP (197 mL/min/m(2)) (P<0.05). Using 2.2% SO2 acidic sweep gas increased PMP CO2 removal by 17% (230 mL/min/m(2)) compared to pure oxygen sweep gas control (P<0.05); device outlet blood pH was 7.38 units. When employing both CA-PMP and 2.2% SO2 sweep gas, CO2 removal increased by 109% (411 mL/min/m(2)) (P<0.05); device outlet blood pH was 7.35 units. Dilute acidic sweep gas increases CO2 removal, and when used in combination with bioactive CA-HFMs has a synergistic effect to more than double CO2 removal while maintaining physiologic pH. Through these technologies the next generation of intravascular and paracorporeal respiratory assist devices can remove more CO2 with smaller blood contacting surface areas.

STATEMENT OF SIGNIFICANCE

A clinical need exists for more efficient respiratory assist devices which utilize low blood flow rates (<500 mL/min) to regulate blood CO2 in patients suffering from acute lung failure. Literature has demonstrated approaches to chemically increase hollow fiber membrane (HFM) CO2 removal efficiency by shifting equilibrium from bicarbonate to gaseous CO2, through either a bioactive carbonic anhydrase enzyme coating or bulk blood acidification with lactic acid. In this study we demonstrate a novel approach to local blood acidification using an acidified sweep gas in combination with a bioactive coating to more than double CO2 removal efficiency of HFM devices. To our knowledge, this is the first report assessing an acidic sweep gas to increase CO2 removal from blood using HFM devices.

The holistic view on perfusion monitoring in septic shock

PURPOSE OF REVIEW

To review recent evidence concerning the interactions between hemodynamic and perfusion parameters during septic shock resuscitation, and to propose some basic foundations for a more comprehensive perfusion assessment.

RECENT FINDINGS

Several recent studies have expanded our knowledge about the physiologic determinants and limitations of currently used perfusion parameters such as central venous oxygen saturation and lactate. Macrohemodynamic, metabolic, peripheral and microcirculatory parameters tend to change in parallel in response to fluid loading during initial resuscitation. In contrast, perfusion markers are poorly correlated in patients who evolve with a persistent circulatory dysfunction. Therefore, assessment of perfusion status based solely on a single parameter can lead to inaccurate or misleading conclusions.

SUMMARY

All individual perfusion parameters have extensive limitations to adequately reflect tissue perfusion during persistent sepsis-related circulatory dysfunction. A multimodal approach integrating macrohemodynamic, metabolic, peripheral and eventually microcirculatory perfusion parameters may overcome those limitations. This approach may also provide a thorough understanding on the predominant driving forces of hypoperfusion, and lead to physiologically oriented interventions.

Early hyperlactatemia predicts pancreatic fistula after surgery

Background

Postoperative pancreatic fistula (POPF) is a major complication after pancreatic surgery and results from an impaired healing of the pancreatic enteric anastomosis. Whether perioperative hemodynamic fluid management aiming to provide an adequate tissue perfusion could influence the occurrence of POPF is unknown. Serum lactate level is a well-recognized marker of decreased tissue perfusion and is known to be associated with higher morbidity and mortality in various postoperative settings. We aimed to determine in a retrospective high-volume center’s cohort whether postoperative hyperlactatemia could predict POPF occurrence.

Method

We conducted a retrospective analysis of 96 consecutive patients admitted in the intensive care unit (ICU) after pancreaticoduodenectomy or distal pancreatectomy. Univariate analysis was conducted to compare lactate levels at 6 h between patients evolving with versus without POPF. A logistic regression model was developed and included potential confounding factors.

Results

POPF occurred in 28 patients (29 %). Serum lactate level 6 h after admission was significantly higher in the POPF group (2.8 mmol/L [95 % confidence interval (CI): 2.1–3.5] versus 1.8 mmol/L [95 % CI: 1.8–2.4], p-value = 0.04) whereas it did not differ at ICU admission or at 12 h. Despite similar cumulative fluid balance, fluid intake and vasopressor use, hyperlactatemia > 2.5 mmol/L (Odds ratio (OR): 3.58; 95 % CI: 1.22–10.48; p-value = 0.020) and red blood cells transfusion (OR: 1.24; 95 % CI: 1.03–1.49; p-value = 0.022) were found to be independent predictive factors of POPF occurrence.

Conclusion

In patients undergoing partial pancreatectomy, hyperlactatemia measured 6 h after ICU admission is a predictive factor for the occurrence of POPF. Inflammatory changes after surgery may account for this observation and should be further evaluated.

Management of fluid balance: a European perspective

PURPOSE OF REVIEW

Managing fluid balance mandates a clear identification of what goals are being sought at a particular point in the patient's pathway, an accurate assessment of both filling status and the degree of tissue hypoperfusion (if present), and a precise evaluation of response.

RECENT FINDINGS

As no definitive data exist to show how the above targets should be optimally achieved, and with what fluid, many opinions of varied veracity currently exist. A perception from recent surveys is that critical care and intraoperative patients in Europe are more likely to receive synthetic colloid as the primary resuscitation fluid and to have cardiac output monitored by noninvasive or minimally invasive monitoring techniques. However, these preferences are based largely on tradition and local technology developments, albeit with an increasing evidence base for high-risk surgery. There is an increasing consensus that excess fluid should be avoided and that, after the initial resuscitation phase, efforts should be made to keep the patient in neutral (or perhaps negative) balance, unless clinically indicated. Likewise, the intravascular compartment should not remain underfilled if tissue hypoperfusion exists, acknowledging the above difficulties in agreeing upon definition and diagnosis.

SUMMARY

Achieving and maintaining optimal fluid balance remains a significant challenge; better monitoring tools and definitive studies are needed.

Lactate in the acute phase of ST-elevation myocardial infarction treated with mechanical revascularization: a single-center experience

AIMS

The prognostic role (if any) of lactate for early mortality in patients with ST-elevation myocardial infarction (STEMI) submitted to primary percutaneous coronary intervention (PCI) is so far not elucidated. We therefore assessed whether lactic acid (LA) was a prognostic predictor for early mortality in 807 patients with STEMI submitted to primary PCI consecutively admitted to our intensive cardiac care unit (ICCU) from January 1, 2006, to December 31, 2009.

RESULT

Higher levels of LA were found in older patients (P = .025) and were associated with a progressive decline in estimated glomerular filtration rate (P < .001) and in ejection fraction (P < .001). The increase in LA values paralleled the progressive increase in glucose values, peak glycemia, troponin I, N-terminal pro-brain natriuretic peptide, and uric acid (P < .001, P < .001, P < .001, P = .018, and P = .006, respectively). The in-ICCU mortality rate was highest in the third LA tertile (P < .001). Lactate levels were independent predictors for in-hospital mortality only in patients with Killip classes III to IV (odds ratio [OR], 1.17; 95% confidence interval [CI], 1.05-1.30, P = .003). In addition, age (OR, 1.11; 95% CI, 1.03-1.19, P = .006) and leukocytes (OR, 1.17; 95% CI, 1.03-1.33, P = .015) were independent predictors for in-hospital mortality when adjusted for PCI failure.

CONCLUSION

In patients with STEMI submitted to primary PCI, blood lactate is a prognostic marker for early mortality only in the subgroup with advanced Killip class. The degree of hemodynamic impairment (as indicated by Killip class), of myocardial ischemia (as inferred by troponin I), and glucose values are the main factors influencing lactate concentrations in the early phase of STEMI.