Levosimendan in intensive care and emergency medicine: literature update and expert recommendations for optimal efficacy and safety

The inodilator levosimendan, in clinical use for over two decades, has been the subject of extensive clinical and experimental evaluation in various clinical settings beyond its principal indication in the management of acutely decompensated chronic heart failure. Critical care and emergency medicine applications for levosimendan have included postoperative settings, septic shock, and cardiogenic shock. As the experience in these areas continues to expand, an international task force of experts from 15 countries (Austria, Belgium, China, Croatia, Finland, France, Germany, Greece, Hungary, Italy, the Netherlands, Spain, Sweden, Switzerland, and the USA) reviewed and appraised the latest additions to the database of levosimendan use in critical care, considering all the clinical studies, meta-analyses, and guidelines published from September 2019 to November 2021. Overall, the authors of this opinion paper give levosimendan a "should be considered" recommendation in critical care and emergency medicine settings, with different levels of evidence in postoperative settings, septic shock, weaning from mechanical ventilation, weaning from veno-arterial extracorporeal membrane oxygenation, cardiogenic shock, and Takotsubo syndrome, in all cases when an inodilator is needed to restore acute severely reduced left or right ventricular ejection fraction and overall haemodynamic balance, and also in the presence of renal dysfunction/failure.

[S3 guidelines on intensive medical care of cardiac surgery patients : Hemodynamic monitoring and cardiovascular system-an update]

An update of the S3- guidelines for treatment of cardiac surgery patients in the intensive care unit, hemodynamic monitoring and cardiovascular system was published by the Association of Scientific Medical Societies in Germany (AWMF) in January 2018. This publication updates the guidelines from 2006 and 2011. The guidelines include nine sections that in addition to different methods of hemodynamic monitoring also reviews the topic of volume therapy as well as vasoactive and inotropic drugs. Furthermore, the guidelines also define the goals for cardiovascular treatment. This article describes the most important innovations of these comprehensive guidelines.

Positive end-expiratory pressure titration at bedside using electrical impedance tomography in post-operative cardiac surgery patients

BACKGROUND

Post-operative positive end-expiratory pressure (PEEP) setting to minimize the risk of ventilator-associated lung injury is still controversial. Assessment of regional ventilation distribution by electrical impedance tomography (EIT) might be superior as compared with global parameters. The aim of this prospective observational study was to compare global dynamic compliance (CRS ) with different EIT indices during a short clinical applicable descending PEEP trial.

METHODS

Twenty mechanically ventilated patients after elective cardiac surgery received a standard recruitment manoeuvre (RM) following descending PEEP trial in steps of 2 cmH2 O from PEEP 14 cmH2 O to 6 cmH2 O. During baseline and all PEEP steps, CRS was assessed and regional ventilation distribution was measured by means of EIT. The individual 'best' PEEP values for the derived EIT indices and CRS were calculated and compared.

RESULTS

The descending PEEP trial lasted less than 10 min. CRS increased after the RM and showed a maximum value at PEEP 8 cmH2 O. Ventilation distribution shifted more to dependent lung regions after RM and back to more non-dependent regions during the PEEP trial. Individual 'best' PEEP by CRS showed significantly lower values than 'best' PEEP by ventilation distribution measured with EIT indices.

CONCLUSION

During a short descending PEEP trial at bedside, EIT is capable of following the status of regional ventilation distribution in ventilated patients. The 'best' PEEP value identified by individual maximum CRS was lower than optimal PEEP levels as determined by means of EIT indices. EIT could help setting PEEP in post-operative ventilated patients.

Relationship between mixed venous oxygen saturation and regional cerebral oxygenation in awake, spontaneously breathing cardiac surgery patients

BACKGROUND

In search of a non-invasive method for estimation of the oxygen balance this prospective study evaluates the relationship between regional cerebral oxygenation (rScO2) and mixed venous oxygen saturation in awake, spontaneously breathing patients after cardiac surgery.

METHODS

After approval by the local ethical committee and written informed consent, 26 consecutive patients after cardiac surgery with cardiopulmonary bypass were enrolled. On intensive care unit (ICU), several hours after extubation, patients were connected to the INVOS 5100 cerebral monitor. Blood samples for determination of mixed venous oxygen saturation (SvO2) and central venous oxygen saturation (ScvO2) were drawn successively and rScO2 was documented. Patients were studied twice, breathing room air for the first measurement cycle, and breathing 4L/min supplemental oxygen by face mask, achieving a transcutaneous oxygen saturation above 98%, for a second measurement.

RESULTS

Hemodynamic variables, hemoglobin and arterial carbon dioxide tension (PaCO2) remained stable between the two measurement cycles. Without oxygen, SvO2 and rScO2 showed a bias of -2.0%, limits of agreement (LOA) of -15.0 to 10.9% and a percentage error (PE) of 20.3%. SvO2 and ScvO2 showed a bias of -3.9%, LOA of -13.9 to 6.2% and PE 15.7%. With oxygen, the bias between SvO2 and rScO2 was -2.5%, LOA -14.2 to 9.2%, PE 17.2%. Between SvO2 and ScvO2 the bias was -4.1%, LOA -10.2 to 2.1%, PE 9.0%.

CONCLUSION

The rScO2 measured by near infrared spectroscopy was sufficiently representing mixed venous oxygen saturation in awake, hemodynamically stable, spontaneously breathing patients after cardiac surgery. The agreement was comparable to the agreement between SvO2 and ScvO2 with smaller differences in the lower ranges of SvO2.

S3 guidelines for intensive care in cardiac surgery patients: hemodynamic monitoring and cardiocirculary system

Hemodynamic monitoring and adequate volume-therapy, as well as the treatment with positive inotropic drugs and vasopressors are the basic principles of the postoperative intensive care treatment of patient after cardiothoracic surgery. The goal of these S3 guidelines is to evaluate the recommendations in regard to evidence based medicine and to define therapy goals for monitoring and therapy. In context with the clinical situation the evaluation of the different hemodynamic parameters allows the development of a therapeutic concept and the definition of goal criteria to evaluate the effect of treatment. Up to now there are only guidelines for subareas of postoperative treatment of cardiothoracic surgical patients, like the use of a pulmonary artery catheter or the transesophageal echocardiography. The German Society for Thoracic and Cardiovascular Surgery (Deutsche Gesellschaft für Thorax-, Herz- und Gefässchirurgie, DGTHG) and the German Society for Anaesthesiology and Intensive Care Medicine (Deutsche Gesellschaft für Anästhesiologie und lntensivmedizin, DGAI) made an approach to ensure and improve the quality of the postoperative intensive care medicine after cardiothoracic surgery by the development of S3 consensus-based treatment guidelines. Goal of this guideline is to assess the available monitoring methods with regard to indication, procedures, predication, limits, contraindications and risks for use. The differentiated therapy of volume-replacement, positive inotropic support and vasoactive drugs, the therapy with vasodilatators, inodilatators and calcium sensitizers and the use of intra-aortic balloon pumps will also be addressed. The guideline has been developed following the recommendations for the development of guidelines by the Association of the Scientific Medical Societies in Germany (AWMF). The presented key messages of the guidelines were approved after two consensus meetings under the moderation of the Association of the Scientific Medical Societies in Germany (AWMF).

[Anti-inflammatory effects of pentoxifylline: importance in cardiac surgery]

Initially introduced as a rheologic agent for use in intermittent claudication due to peripheral artery disease and in ischemic cerebrovascular disease, the methylxanthine derivative pentoxifylline (PTX) has been shown to possess several anti-inflammatory properties which make this drug an interesting immunomodulating adjunct for the management of patients undergoing cardiac surgery. As an unspecific phosphodiesterase inhibitor PTX ameliorates the inflammatory response following a septic stimulus and blunts organ dysfunction after ischemia-reperfusion injury. Apart from this several small clinical studies have shown that the use of PTX may blunt the inflammatory response induced by cardiac surgery using a cardiopulmonary bypass. Additionally it has been shown that the perioperative application of this drug may improve postoperative function of organs at risk, such as the kidneys and liver.

Goal-directed hemodynamic optimization in high-risk cardiac surgery patients: a tale from the past or a future obligation?

The present manuscript summarizes the available evidence on outcome-related hemodynamic variables and ''goal-directed hemodynamic optimization'' strategies in patients undergoing cardiac surgery.

Respiratory protection during high-fidelity simulated resuscitation of casualties contaminated with chemical warfare agents

Emergency room personnel are threatened by secondary poisoning when treating victims affected by chemical warfare agents. Therefore, resuscitation skills practised with respiratory protection equipment in place require evaluation. We investigated the influence of wearing air-purifying respirators on the simulated resuscitation of chemical warfare agent casualties. We studied 22 anaesthetic trainees in a simulated resuscitation scenario requiring five set tasks, either unprotected, wearing a binocular visor respirator or a panoramic visor respirator in a randomised, crossover study. Treatment times did not differ between the three groups, with mean (SD) times to complete the tasks being 122 (8) s without a mask, 126 (7) s when wearing the panoramic visor mask and 129 (8) s when wearing the binocular respirator mask. All anaesthetists preferred the panoramic visor in terms of visual orientation but 88% of them rated the binocular mask as being more comfortable. Modern respirators have a negligible effect on simulated resuscitation scenarios for victims affected by chemical warfare agents. Panoramic visor respirators allow better visual orientation for anaesthetists during simulated resuscitation.

[Guidelines for intensive care in cardiac surgery patients: haemodynamic monitoring and cardio-circulatory treatment guidelines of the German Society for Thoracic and Cardiovascular Surgery and the German Society of Anaesthesiology and Intensive Care Medicine]

Hemodynamic monitoring and adequate volume-therapy, as well as the treatment with positive inotropic drugs and vasopressors, are the basic principles of the postoperative intensive care treatment of patient after cardiothoracic surgery. The goal of these S3 guidelines is to evaluate the recommendations in regard to evidence based medicine and to define therapy goals for monitoring and therapy. In context with the clinical situation the evaluation of the different hemodynamic parameters allows the development of a therapeutic concept and the definition of goal criteria to evaluate the effect of treatment. Up to now there are only guidelines for subareas of postoperative treatment of cardiothoracic surgical patients, like the use of a pulmonary artery catheter or the transesophageal echocardiography. The German Society for Thoracic and Cardiovascular Surgery and the German Society for Anaesthesiology and Intensive Care Medicine made an approach to ensure and improve the quality of the postoperative intensive care medicine after cardiothoracic surgery by the development of S3 consensus-based treatment guidelines. Goal of this guideline is to assess available monitoring methods and their risks as well as the differentiated therapy of volume-replacement, positive inotropic support and vasoactive drugs, the therapy with vasodilators, inodilators and calcium-sensitizers and the use of intra-aortic balloon pumps. The guideline has been developed according to the recommendations for the development of guidelines by the Association of the Scientific Medical Societies in Germany (AWMF). The presented key messages of the guidelines were approved after two consensus meetings under the moderation of the Association of the Scientific Medical Societies in Germany (AWMF).

Focussing cellular function. Metabolic monitoring in perioperative and Intensive Care Medicine

In the clinical field microdialysis today is a routine technique for monitoring the chemistry of tissues and organs in physiological and pharmacological research on animals. In more than 10.000 papers on microdialysis research it is used to uncover physiological mechanisms and the influence of drugs in almost every organ of the body. Since the first papers describing microdialysis in the human brain microdialysis has become a technique for routine monitoring of energy metabolism especially in neurointensive care. This paper gives an account of the microdialysis technique describing its practical use and interpretation in monitoring energy metabolism and ischemia in different organs with respect to the field of perioperative and intensive care medicine. This article gives an overview over current results of clinical studies using microdialysis in critical care medicine and tries to focus on possible indications for clinical biochemical monitoring. However, despite numerous publications available microdialysis has not been shown to improve outcome of the patients yet.

Renal dysfunction according to the ADQI-RIFLE system and clinical practice patterns after cardiac surgery in Germany

AIM

The aim of this study was to determine the incidence of renal dysfunction according to the Acute-Dialysis-Quality Initiative-(ADQI)-RIFLE grading system in cardiac surgery in Germany in 2003 and to determine if variations in the incidence of renal dysfunction are related to clinical practice patterns.

METHODS

DESIGN

prospective cohort analysis and practice pattern survey.

MEASUREMENTS

81 hospitals were requested to report prospectively sampled quality-management-data on patient load, case mix, aortic-cross-clamp-time, baseline and maximal plasma creatinine (CreaP), new-onset-renal-replacement-therapy, and clinical practice concerning the use of fluids, inotropic and vasopressor drugs, and diuretics. Fifty-one (63%) centers answered the survey. Twenty-six centers (32%)(representative for 29 623 patients(reported creatinine data.

RESULTS

The incidence of a 50%, 100%, or 150% increase in plasma creatinine (graded as risk, injury, and failure according to the ADQI-RIFLE-system) were 9% (2-40%), 5% (0.8-30%), and 2% (0.6-33%), respectively, overall 15.4% (3.1-75%). The incidence of new-onset renal-replacement-therapy was 4.5% (0.6-24%). Centers with a low incidence of renal dysfunction 8.7% (3.1-15.4%)differed from those with a high incidence 51% (15.7-75%)by being more liberal with fluids, not preferring dopamine in ''renal'' or inotropic doses, and preferring noradrenaline as a vasopressor (all: P<0.05), but not by case mix, frequency of urgent or emergency cases, and the use of loop diuretics.

CONCLUSIONS

Renal dysfunction is a frequent complication following cardiac surgery in many German heart centers. The variance between centers may not be explained by patient heterogeneity and may be related to different strategies regarding fluid therapy and the use of inotropes and vasopressors.

Effects of intra-aortic balloon counterpulsation on parameters of tissue oxygenation

BACKGROUND AND OBJECTIVE

To investigate the effects of intra-aortic balloon pump therapy on parameters of global and regional oxygenation in patients undergoing cardiac surgery.

METHODS

As part of a large surveillance study in cardiac surgery patients (n=266) we retrospectively analyzed the course of 28 patients requiring intra-aortic balloon pump therapy. Patients were grouped according to the time point of pump insertion (during weaning from cardiopulmonary bypass: group early intra-aortic balloon pumping (n=17); after admission to the intensive care unit: group late intra-aortic balloon pumping (n=9). Haemodynamic and tonometric variables, arterial lactate, and use of catecholamines were measured hourly.

MEASUREMENTS AND RESULTS

Cardiac index increased in both groups after intra-aortic balloon pump insertion (2.2+/-0.5 baseline; 3.4+/-0.8 L min-1 m-2 4 h later (group early intra-aortic balloon pumping); 2.8+/-0.5 baseline, 3.6+/-L min-1 m-2 4 h later (group later intra-aortic balloon pumping), each P<0.05), there were no differences between groups. Arterial lactate values increased in group later intra-aortic balloon pumping after pump insertion to a maximum 2 h later (8.4+/-6.1 mmol L-1 baseline; 12.7+/-7.4 mmol L-1, P<0.05), and decreased continuously afterwards. The difference of arterial and gastric CO2 showed a sharp decrease after pump insertion in group later intra-aortic balloon pumping (26.4+/-9.8 baseline; 7.0+/-11.1 mmHg, P<0.05). There were no differences between groups. Epinephrine doses were higher in group later intra-aortic balloon pumping (P<0.05).

CONCLUSIONS

Intra-aortic balloon pump therapy improved global and regional splanchnic oxygenation in cardiac surgery patients with low-cardiac-output syndrome. Gastro-intestinal tonometry could provide additional information concerning tissue oxygenation. Patients with later intra-aortic balloon pump insertion needed more catecholamine therapy to achieve similar haemodynamic values.

High myocardial lactate concentration is associated with poor myocardial function prior to cardiopulmonary bypass

AIM

This study was designed to analyse the relationship between myocardial lactate--determined by microdialysis--and hemodynamics during coronary artery bypass grafting (CABG) with cardiopulmonary bypass (CPB).

METHODS

Twenty consecutive patients with coronary artery disease were enrolled for this prospective, observational study. Microdialysis measurements were performed in the apical region of the heart during periods of 15 to 20 min before, during, and after CPB; hemodynamics and plasma lactate concentrations were determined correspondingly. Correlation analysis revealed a relationship between myocardial lactate concentration and right ventricular ejection fraction at baseline (Spearman's r: 0.6; P=0.02). Patients were thus grouped according to the myocardial lactate concentration at baseline into a high-lactate group (2.5+/-0.7 mmol.l(-1), n=10) and low-lactate group (0.9+/-0.5 mmol.l(-1), n=10).

RESULTS

Preoperative left ventricular ejection fraction was not different between the groups (high-lactate group: 53+/-16%; low-lactate group: 57+/-15%; P=n.s.) Patients in the high-lactate-group had a lower stroke volume index (P=0.005) and right ventricular ejection fraction (P=0.04) before, and higher central venous and pulmonary artery pressures (P<0.01) after CPB. Plasma lactate was significantly higher during CPB in the high-lactate-group (P<0.05). No correlation was observed between myocardial and plasma lactate. Six patients in the high-lactate but none in the low-lactate-group needed inotropic support after weaning from CPB (P=0.01).

CONCLUSIONS

These data are suggestive of an association between subtle myocardial ischemia--detected by microdialysis--and perioperative myocardial dysfunction in patients undergoing CABG. The microdialysis technique may be a valuable adjunct for monitoring myocardial metabolism during cardiac surgery.

Metabolic stress during hypoglycaemia clamp assessed by microdialysis

AIM

Microdialysis allows the biochemical analysis of interstitial fluids as a bedside procedure. This technique is of interest to evaluate the glucose dependent metabolism in hypoglycaemic patients. It was the aim to perform subcutaneous and blood microdialysis during hypoglycaemic clamp experiments in 12 healthy young men to reveal basis data for critical care microdialysis practice.

METHODS

The hyperinsulinaemic clamp was induced with a continuous infusion of 1.5 mU min(-1) kg(-1) insulin (H-insulin, Hoechst, Frankfurt, Germany). A 20% dextrose solution simultaneously was infused at a variable rate to control blood glucose levels. For hypoglycaemia blood glucose levels were reduced to 40 mg/dL for a 30 min period. Glucose, lactate, pyruvate and glycerol concentrations were semicontinuously measured.

RESULTS

The absolute concentrations of glucose and glycerol in blood vs subcutaneous microdialysate were significant different during observation. Until the end of hypoglycaemia, glucose concentration in both compartments declined in parallel, followed by an increase thereafter. During the clamp the subcutaneous glycerol increased threefold, whereas blood glycerol rose with a delay of 15 min and increased only twofold. After the clamp in both compartments glycerol values normalized. The lactate-pyruvate-ratio persisted in normal range throughout the examination.

CONCLUSIONS

In our experiment subcutaneous lipolysis increased faster and more profound than blood microdialysis. We propose the microdialysis technique as an additional monitoring tool in hypoglycaemia patients.

Clinical biochemical tissue monitoring during ischaemia and reperfusion in major vascular surgery

BACKGROUND

Major vascular surgery with aortic cross-clamping is associated with temporary ischaemia of the lower limb due to lack of tissue blood flow. The present study was designed to determine if the short-term changes in cellular metabolism occurring during this situation can be detected by subcutaneous microdialysis. It was also hoped to ascertain if this new technique is useful in the continuous bedside monitoring of metabolism during aortic surgery.

METHODS

In a controlled clinical study 20 patients undergoing elective aortic surgery were monitored using microdialysis probes that were inserted in the subcutaneous tissue of the left lower limb and a non-ischaemic region (shoulder). Interstitial fluid was obtained and the concentrations of glucose and lactate during lower limb ischaemia and during reperfusion were measured and compared with concentrations observed in fluid obtained from the non-ischaemic control tissue.

RESULTS

Circulatory occlusion caused an immediate and significant decrease in the glucose/lactate ratio from 3.1+/-1.3 to 0.48+/-0.5 (P<0.05) that returned to preocclusion values within 2 h of commencing reperfusion.

CONCLUSION

We suggest that microdialysis may be used both to assess acute changes in tissue metabolism during ischaemic periods and also to act as an additional tool for the detection of peri-operative acute variations in limb blood flow.

Metabolic changes detected by microdialysis during endotoxin shock and after endotoxin preconditioning

OBJECTIVE

Preconditioning with low doses of endotoxin has been shown to induce endotoxin hyporesponsiveness. The present study was designed to assess the metabolic response of various tissues during endotoxemia and after pretreatment with endotoxin.

DESIGN

Controlled experimental animal study.

SETTING

Research laboratory of a university hospital.

MEASUREMENTS AND RESULTS

Ten pigs were randomly assigned to a control ( n = 5) or a treatment group ( n = 5), the latter receiving incremental doses of endotoxin 5-2 days prior the experiments. Apart from hemodynamics and oxygen transport variables, lactate, glucose, and glycerol were measured in muscle, subcutaneous fat, and hepatic tissue using microdialysis. Endotoxin was infused (1 micro g.kg.h) until the animals died. A significant increase in tissue lactate (eightfold) and glycerol (fivefold) was observed in the control animals. This effect was almost completely abolished in the endotoxin pretreated group. Endotoxin pretreatment had no significant effects on mean arterial pressure [56 (range 34-89) mmHg vs 70 (47-88) mmHg, n.s.] or cardiac output [4.8 (3.0-5.9) l/min vs 3.2 (2.1-4.2) l/min, n.s.], but significantly improved arterial pO(2) and pH ( P<0.05). Increase of oxygen extraction was higher in control animals [from 34% (range 24-47%) to 72% (range 61-79%)] compared to the pretreatment group [from 30% (range 22-42%) to 44% (range 34-50%), P<0.05]. Endotoxin pretreatment increased survival time from 5.3 h (5.0-5.8) to 8.0 h (7.0-8.5) ( P<0.05), respectively.

CONCLUSIONS

Microdialysis monitoring revealed that endotoxin preconditioning ameliorates the increase in tissue metabolism during endotoxemia, accompanied by decreased systemic oxygen demand despite unchanged global hemodynamics.

[Microdialysis as a procedure for evaluating intestinal hypoxia--an animal experiment approach]

Usual ICU monitoring of patients with abdominal pathology provides no detailed information about hepatosplanchnic haemodynamics or intestinal metabolism. In our animal experiment, the effects of systemic hypoxia on microdialysis measurements of the peritoneum in comparison with the ischiocrural muscle as reference were investigated in 7 rats. The parameter of interest was the course of glucose metabolism reflecting sympathoadrenergic activity during the experiment. Measurements were obtained at timed intervals at baseline, under hypoxia, and during reoxygenation. After induction of systemic hypoxia, the peritoneal microdialysis showed significantly higher levels of glucose in comparison with the ischiocrural muscle. The results indicate hypermetabolic activity or a hypersympathetic response of the bowel in response to hypoxic stress. In the clinical setting, the bowel has an important role in the development of multiorgan failure. Microdialysis may therefore be an interesting tool for the early detection of hypoxic metabolism during and after abdominal procedures.

[Cardio-renal-axis--physiology, pathophysiology, and clinical relevance?]

It has been known for years that variations in atrial stretch and intrathoracic blood volume may affect kidney function. Interestingly, little information on this topic can be found in the recent literature of critical care medicine and anesthesiology. Hence, this review focuses on the role of low pressure cardiopulmonary and arterial baroreceptors in the regulation of kidney function and the neuro-endocrine mechanisms behind the so-called "cardio-renal axis". The physiological mechanisms presented in this review may have clinical impact with regard to strategies for the prevention and treatment of acute renal failure and question the usefulness of diuretics to improve kidney function during several shock states.

[Microdialysis for metabolic monitoring during septicemia]

Currently, metabolic changes in ICU patients in critical states are determined mainly by indirect laboratory parameters (e.g. blood lactate). Microdialysis is a new means of performing metabolic monitoring that permits organ-specific objectification on the basis of interstitial fluid samples. Continuous endotoxin infusion was administered to 10 female pigs and, in addition to hemodynamic monitoring, lactate and glycerol in the subcutaneous, intramuscular and hepatic tissue were measured by microdialysis. The interstitial concentrations of lactate and glycerol rose significantly under endotoxaemia and showed an earlier increase than blood lactate levels. Microdialysis is simple to apply, appears to be a suitable means of obtaining important information about cellular metabolic changes in different tissues of the critically ill patient, and can detect subtle changes that laboratory parameters can identify only later and incompletely.