General anesthesia bullies the gut: a toxic relationship with dysbiosis and cognitive dysfunction

Perioperative neurocognitive disorder (PND) is a common surgery outcome affecting up to a third of the elderly patients, and it is associated with high morbidity and increased risk for Alzheimer's disease development. PND is characterized by cognitive impairment that can manifest acutely in the form of postoperative delirium (POD) or after hospital discharge as postoperative cognitive dysfunction (POCD). Although POD and POCD are clinically distinct, their development seems to be mediated by a systemic inflammatory reaction triggered by surgical trauma that leads to dysfunction of the blood-brain barrier and facilitates the occurrence of neuroinflammation. Recent studies have suggested that the gut microbiota composition may play a pivotal role in the PND development by modulating the risk of neuroinflammation establishment. In fact, modulation of gut microbiome composition with pre- and probiotics seems to be effective for the prevention and treatment of PND in animals. Interestingly, general anesthetics seem to have major responsibility on the gut microbiota composition changes following surgery and, consequently, can be an important element in the process of PND initiation. This concept represents an important milestone for the understanding of PND pathogenesis and may unveil new opportunities for the development of preventive or mitigatory strategies against the development of these conditions. The aim of this review is to discuss how anesthetics used in general anesthesia can interact and alter the gut microbiome composition and contribute to PND development by favoring the emergence of neuroinflammation.

ECOG and BMI as preoperative risk factors for severe postoperative complications in ovarian cancer patients: results of a prospective study (RISC-GYN-trial)

BACKGROUND

Accompanying co-morbidities in patients with ovarian cancer are of major relevance for scheduling debulking surgery, especially in the anesthesiological consultations. Aim of this study was to evaluate the impact of co-morbidities and patient characteristics on postoperative complications.

METHODS

Patients undergoing maximal cytoreductive surgery were prospectively enrolled from October 2015 to January 2017. Various variables were recorded, such as the Charlson comorbidity index, Eastern cooperative oncology group scale of performance status (ECOG PS) and the American society of anesthesiologists physical status classification system (ASA PS). Surgical complications were graded using the Clavien-Dindo criteria. Logistic regression models were used to analyze risk factors for severe postoperative complications.

RESULTS

Of 106 enrolled patients, 19 (17.9%) developed severe postoperative complications grade ≥ IIIb according to Clavien-Dindo criteria. In the multivariable regression analysis impaired (ECOG PS) > 1 (odds ratio OR) 13.34, 95% confidence interval (CI) 1.74-102.30, p = 0.01), body mass index (BMI) > 25 kg/m² (OR 10.48, 95% CI 2.38-46.02, p = 0.002) along with the use of intraoperative norepinephrine > 0.11 µg/kg/min (OR 4.69, 95% CI 1.13-19.46, p = 0.03) and intraoperative fresh frozen plasma (FFP) > 17 units (OR 4.11, 95% CI 1.12-15.14, p = 0.03) appeared as significant predictors of severe postoperative complications.

CONCLUSION

We demonstrated that neither the presence of a certain comorbidity nor the summation of the co-morbidities were associated with adverse outcome. Patient characteristics, such as ECOG PS > 1 and obesity (BMI > 25 kg/m²), are highly predictive factors for severe postoperative complications. The analysis of intraoperative data showed that the need for more than > 0.11 µg/kg/min of norepinephrine and transfusions of FFPs more than 17 units were strongly associated with severe postoperative complications.

Anaesthesia and ICU sedation with sevoflurane do not reduce myocardial injury in patients undergoing cardiac surgery: A randomized prospective study

BACKGROUND

To evaluate the effect of anaesthesia and ICU sedation with sevoflurane to protect the myocardium against ischemia-reperfusion injury associated to cardiac surgery assessed by troponin release.

METHODS

We performed a prospective, open-label, randomized study in cardiac surgery with cardiopulmonary bypass. Patients were randomized to an algorithm-based intervention group and a control group. The main outcome was the perioperative kinetic of cardiac troponin I (cTnI). The secondary outcomes included composite endpoint, GDF-15 (macrophage inhibitory cytokine-1) value, arterial lactate levels, and the length of stay (LOS) in the ICU.

RESULTS

Of 82 included patients, 81 were analyzed on an intention-to-treat basis (intervention group: n = 42; control group: n = 39). On inclusion, the intervention and control groups did not differ significantly in terms of demographic and surgical data. The postoperative kinetics of cTnI did not differ significantly between groups: the mean difference was 0.44 ± 1.09 μg/ml, P = .69. Incidence of composite endpoint and GDF-15 values were higher in the sevoflurane group than in propofol group. The intervention and control groups did not differ significantly in terms of ICU stay and hospital stay.

CONCLUSION

The use of an anaesthesia and ICU sedation with sevoflurane was not associated with a lower incidence of myocardial injury assessed by cTnI. Sevoflurane administration was associated with higher prevalence of acute renal failure and higher GDF-15 values.

[Perioperative pharmacological circulatory support in daily clinical routine]

Perioperative phases of hypotension are associated with an increase in postoperative complications and organ damage. Whereas some years ago hemodynamic stabilization was primarily carried out by volume supplementation, in recent years the use and dosing of cardiovascular-active substances has significantly increased. But like intravascular volume therapy, also substances with a cardiovascular effect have therapeutic margins, and thus, potential side effects. This review article discusses indications for each cardiovascular-active agent, weighing up advantages and disadvantages. Special attention is paid to the question how to administrate them: central venous catheter vs. peripheral indwelling venous cannula. The authors come to the conclusion that it is not a question of whether it is principally allowed to apply cardiovascular-active drugs via peripheral veins but more importantly, what should be taken into consideration if a peripheral venous access is used. This article provides concise recommendations.

Do intravascular hypo- and hypervolaemia result in changes in central blood volumes?

BACKGROUND

Hypovolaemia is generally believed to induce centralization of blood volume. Therefore, we evaluated whether induced hypo- and hypervolaemia result in changes in central blood volumes (pulmonary blood volume (PBV), intrathoracic blood volume (ITBV)) and we explored the effects on the distribution between these central blood volumes and circulating blood volume (Vd circ).

METHODS

Six anaesthetized, spontaneously breathing Foxhound dogs underwent random blood volume alterations in steps of 150 ml (mild) to 450 ml (moderate), either by haemorrhage, retransfusion of blood, or colloid infusion. PBV, ITBV and Vd circ were measured using (transpulmonary) dye dilution. The PBV/Vd circ ratio and the ITBV/Vd circ ratio were used as an assessment of blood volume distribution.

RESULTS

68 blood volume alterations resulted in changes in Vdcirc ranging from -33 to +31%. PBV and ITBV decreased during mild and moderate haemorrhage, while during retransfusion, PBV and ITBV increased during moderate hypervolaemia only. The PBV/Vd circ ratio remained constant during all stages of hypo- and hypervolaemia (mean values between 0.20-0.22). This was also true for the ITBV/Vd circ ratio, which remained between 0.31 and 0.32, except for moderate hypervolaemia, where it increased slightly to 0.33 (0.02), P<0.05.

CONCLUSIONS

Mild to moderate blood volume alterations result in changes of Vd circ, PBV and ITBV. The ratio between the central blood volumes and Vd circ generally remained unaltered. Therefore, it could be suggested that in anaesthetized spontaneously breathing dogs, the cardiovascular system maintains the distribution of blood between central and circulating blood volume.

Vascular Dilation, Tachycardia, and Increased Inotropy Occur Sequentially with Increasing Epinephrine Dose Rate, Plasma and Myocardial Concentrations, and cAMP

BACKGROUND

While epinephrine infusion is widely used in critical care for inotropic support, there is no direct method to detect the onset and measure the magnitude of this response. We hypothesised that surrogate measurements, such as heart rate and vascular tone, may indicate if the plasma and tissue concentrations of epinephrine and cAMP are in a range sufficient to increase myocardial contractility.

METHODS

Cardiovascular responses to epinephrine infusion (0.05-0.5 mcgkg(-1)min(-1)) were measured in rats using arterial and left ventricular catheters. Epinephrine and cAMP levels were measured using ELISA techniques.

RESULTS

The lowest dose of epinephrine infusion (0.05 mcgkg(-1)min(-1)) did not raise plasma epinephrine levels and did not lead to cardiovascular response. Incremental increase in epinephrine infusion (0.1 mcgkg(-1)min(-1)) elevated plasma but not myocardial epinephrine levels, providing vascular, but not cardiac effects. Further increase in the infusion rate (0.2 mcgkg(-1)min(-1)) raised myocardial tissue epinephrine levels sufficient to increase heart rate but not contractility. Inotropic and lusitropic effects were significant at the infusion rate of 0.3 mcgkg(-1)min(-1). Correlation of plasma epinephrine to haemodynamic parameters suggest that as plasma concentration increases, systemic vascular resistance falls (EC50=47 pg/ml), then HR increases (ED50=168 pg/ml), followed by a rise in contractility and lusitropy (ED50=346 pg/ml and ED50=324 pg/ml accordingly).

CONCLUSIONS

The dose response of epinephrine is distinct for vascular tone, HR and contractility. The need for higher doses to see cardiac effects is likely due to the threshold for drug accumulation in tissue. Successful inotropic support with epinephrine cannot be achieved unless the infusion is sufficient to raise the heart rate.

Propofol increases morbidity and mortality in a rat model of sepsis

INTRODUCTION

Severe sepsis is associated with approximately 50% mortality and accounts for tremendous healthcare costs. Most patients require ventilatory support and propofol is commonly used to sedate mechanically ventilated patients. Volatile anesthetics have been shown to attenuate inflammation in a variety of different settings. We therefore hypothesized that volatile anesthetic agents may offer beneficial immunomodulatory effects during the course of long-term intra-abdominal sepsis in rats under continuous sedation and ventilation for up to 24 hours.

METHODS

Sham operation or cecal ligation and puncture (CLP) was performed in adult male Wistar rats followed by mechanical ventilation. Animals were sedated for 24 hours with propofol (7 to 20 mg/kg/h), sevoflurane, desflurane or isoflurane (0.7 minimal alveolar concentration each).

RESULTS

Septic animals sedated with propofol showed a mean survival time of 12 hours, whereas >56% of all animals in the volatile groups survived 24 hours (P <0.001). After 18 hours, base excess in propofol + CLP animals (-20.6 ± 2.0) was lower than in the volatile groups (isoflurane + CLP: -11.7 ± 4.2, sevoflurane + CLP: -11.8 ± 3.5, desflurane + CLP -14.2 ± 3.7; all P <0.03). Plasma endotoxin levels reached 2-fold higher levels in propofol + CLP compared to isoflurane + CLP animals at 12 hours (P <0.001). Also blood levels of inflammatory mediators (tumor necrosis factor-α, interleukin-1β, interleukin-10, CXCL-2, interferon-γ and high mobility group protein-1) were accentuated in propofol + CLP rats compared to the isoflurane + CLP group at the same time point (P <0.04).

CONCLUSIONS

This is the first study to assess prolonged effects of sepsis and long-term application of volatile sedatives compared to propofol on survival, cardiovascular, inflammatory and end organ parameters. Results indicate that volatile anesthetics dramatically improved survival and attenuate systemic inflammation as compared to propofol. The main mechanism responsible for adverse propofol effects could be an enhanced plasma endotoxin concentration, leading to profound hypotension, which was unresponsive to fluid resuscitation.

Anesthesia and perioperative management of colorectal surgical patients - specific issues (part 2)

Colorectal surgery carries significant morbidity and mortality, which is associated with an enormous use of healthcare resources. Patients with pre-existing morbidities, and those undergoing emergency colorectal surgery due to complications such as perforation, obstruction, or ischemia / infarction are at an increased risk for adverse outcomes. Fluid therapy in emergency colorectal surgical patients can be challenging as hypovolemic and septic shock may coexist. Abdominal sepsis is a serious complication and may be diagnosed during pre-, intra-, or postoperative periods. Early suspicion and recognition of medical and / or surgical complications are essential. The critical care management of complicated colorectal surgical patients require collaborative and multidisciplinary efforts.

From system to organ to cell: oxygenation and perfusion measurement in anesthesia and critical care

Maintenance or restoration of adequate tissue oxygenation is a main goal of anesthesiologic and intensive care patient management. Pathophysiological disturbances which interfere with aerobic metabolism may occur at any stage in the oxygen cascade from atmospheric gas to the mitochondria, and there is no single monitoring modality that allows comprehensive determination of "the oxygenation". To facilitate early detection of tissue hypoxia (or hyperoxia) and to allow a goal directed therapy targeted at the underlying problem, the anesthesiologist and intensive care physician require a thorough understanding of the numerous determinants that influence cellular oxygenation. This article reviews the basic physiology of oxygen uptake and delivery to tissues as well as the options to monitor determinants of oxygenation at different stages from the alveolus to the cell.

[Diagnosis and management of acute mesenteric ischemia]

The prevalence of significant splanchnic arterial stenoses is increasing, but remains mostly asymptomatic due to abundant collateral circulation. Acute insufficiency of mesenteric arterial blood flow accounts for 60 to 70% of cases of mesenteric ischemia and results mostly from a superior mesenteric embolus. Despite major advances have been achieved in understanding the pathogenic mechanisms of bowel ischemia, its prognosis remains dismal with mortality rates about 60%. The diagnosis of acute mesenteric ischemia depends upon a high clinical suspicion, especially in patients with known risk factors. Rapid diagnosis is essential to prevent intestinal infarction. However, early signs and symptoms of mesenteric ischemia are non specific, and definitive diagnosis often requires radiologic examinations. Early and liberal implementation of angiography has been the major advance over the past 30 years which allowed increasing diagnostic accuracy of acute mesenteric ischemia. CT and MR-based angiographic techniques have emerged as alternatives less invasive and more accurate to analyse splanchnic vessels and evaluate bowel infarction. The goal of treatment of patients with acute mesenteric ischemia is to restore intestinal oxygenation as quickly as possible after initial management that includes rapid hemodynamic monitoring and support. Surgery should not be delayed in patients suspected of having intestinal necrosis.