Conservative management of posterior tracheal wall injury by endoscopic stent placement in children: Preliminary data of three cases

The management of tracheal wall lacerations is debated. Current treatments are mainly derived by the experience on adults and include conservative or surgical treatments depending on the clinical condition of the patient. We report our preliminary data with removable tracheal stents in 3 children with tracheal tears and respiratory failure. If performed in specialized centers with appropriate endoscopic and clinical follow-up, airway stents can be considered a valid and safe conservative treatment for tracheal tears and an alternative to intubation or tracheostomy. Further studies are needed to compare different therapeutic options and better define the management and duration of stent treatment.

The Pathophysiology of Cardiac Surgery-Associated Acute Kidney Injury (CSA-AKI)

Cardiac surgery associated acute kidney injury (CSA-AKI) is a significant clinical problem. Its pathogenesis is complex and multifactorial. It likely involved at least six major injury pathways: exogenous and endogenous toxins, metabolic factors, ischemia and reperfusion, neurohormonal activation, inflammation and oxidative stress. These mechanisms of injury are likely to be active at different times with different intensity and probably act synergistically. Because of such complexity and the small number of randomised controlled investigations in this field only limited recommendations can be made. Nonetheless, it appears important to avoid nephrotoxic drugs and desirable to avoid hyperglycemia in the peri-operative period. The duration of cardiopulmonary bypass should be limited whenever possible. Off-pump surgery, when indicated, may decrease the risk of AKI. Invasive hemodynamic monitoring focussed on attention to maintaining euvolemia, an adequate cardiac output and an adequate arterial blood pressure is desirable. Echocardiography may be useful in minimizing atheroembolic complications. The administration of N-acetylcysteine to protect the kidney from oxidative stress is not recommended. There is marked lack of randomised controlled trials in this field.

Management of Fluid Balance in Continuous Renal Replacement Therapy: Technical Evaluation in the Pediatric Setting

Fluid overload control and fluid balance management represent very important factors in critically ill children requiring renal replacement therapy A relatively high fluid volume administration in children and neonates is often necessary to deliver adequate amounts of blood derivatives, vasopressors, antibiotics, and parenteral nutrition. Fluid balance errors during pediatric continuous renal replacement therapy (CRRT) might significantly impact therapy delivery and have been described as potentially lethal. The aim of this study was to evaluate the accuracy of delivered vs. prescribed net ultrafiltration (UF) during CRRT applied to 2 neonates and 2 small children, either as dialytic treatment alone or during extracorporeal membrane oxygenation (ECMO). In accordance with an Acute Dialysis Quality Initiative workgroup statement, net UF was defined as the “overall amount of fluid extracted from the patient in a given time”. Mean prescribed net UF was 18.5 ml/h (SD=6.7) during neonatal treatments and 70.3 ml/h (SD=22.5) during CRRT in small children. Daily net UF ranged from 200 mL to about 600 mL in the 2 neonates and from 1,200 to 1800 mL in the 2 children. The percentage error of delivered net UF ranged from −1.6% to 5.8% of the prescribed level. The mean error of the ECMO/CRRT patients was 3.024 ml/h vs. 0.45 m/h for the CRRT patients (p<0.001). The same difference was not evident when the 2 neonates were compared with the 2 small children (without considering the presence of ECMO). CRRT and net UF delivery appeared to be accurate, safe, and effective in this small cohort of high-risk pediatric patients.

First Clinical Trial for a New Crrt Machine: The Prismaflex

A new CRRT machine has been designed to fulfill the expectations of nephrologists and intensivists operating in the common ground of critical care nephrology. The new equipment is called “Prismaflex” (Gambro-Dasco, Mirandola, Modena) and it is the natural evolution of the Prisma machine that has been utilized worldwide for CRRT in the last decade.

We performed a preliminary “alfa trial” to establish usability, flexibility and realiability of the new device. Accuracy was also tested by recording various operational parameters during different intermittent and continuous renal replacement modalities. Forty-one runs were conducted on 13 patients and the difference between delivered and prescribed parameters was always lower than 2%. We concluded that the new Prismaflex is a well designed new machine for CRRT and can be safely and effectively utilized in the critical care nephrology setting.

Continuous Hemofiltration dose Calculation in a Newborn Patient with Congenital Heart Disease and Preoperative Renal Failure

Objective

To report a case of a newborn patient with renal failure due to polycystic kidneys requiring renal replacement therapy, and total anomalous pulmonary venous return requiring major cardiosurgical intervention.

Setting

Pediatric cardiosurgery operatory room and pediatric cardiologic intensive care. Patient: A 6-day-old newborn child weighing 3.1 kg.

Results

Renal function (creatinine value and urine output) was monitored during the course of the operation and intraoperative renal replacement therapy was not initiated. Serum creatinine concentration decreased from 4.4 to 3 mg/dL at cardiopulmonary bypass (CPB) start and to 1.5 at the end of surgery: the creatinine decrease was provided by the dilutional effect of CPB priming and the infusion of fresh blood from transfusions together with an adequate filtration rate (800 m/L in about 120 minutes). After the operation, extracorporeal membrane oxygenation (ECMO) for ventricular dysfunction and continuous hemofiltration for anuria refractory to medical therapy were prescribed. The hemofiltration machine was set in parallel with the ECMO machine at a blood flow rate of 60 ml/min and a predilution replacement solution infusion of 600 ml/h (4.5 ml/min of creatinine clearance once adjusted on extracorporeal circuits; 3000 mL/m2 hemofiltration): after a single hemofiltration session lasting 96 hours, serum creatinine reached optimal steady state levels around 0.5 mg/dL on postoperative day 2 and 3.

Conclusion

Administration of intraoperative continuous hemofiltration is not mandatory in the case of a 3-kg newborn patient with established renal failure needing major cardiosurgery: hemodilution secondary to CPB, transfusion of hemoderivates, and optimal UF rate appear to be effective methods for achieving solute removal. If postoperative continuous hemofiltration is started, however, a “dialytic dose” of 4.5 ml/min allows an adequate creatinine clearance, quick achievement of a steady state of serum creatinine concentration and an eventual acceptable rate of inflammatory mediator removal.

Postoperative acute kidney injury

Acute kidney injury (AKI) represents 18-47% of all causes of hospital-acquired AKI and it is associated with a high incidence of morbidity and mortality especially in patients requiring dialysis. Only recently, with the application of new AKI classifications and guidelines (RIFLE, AKIN and KDIGO), a more accurate evaluation of the real incidence of kidney dysfunction in patients undergoing surgery has been detailed. In patients undergoing non-cardiac, non-vascular and non-thoracic surgery several independent preoperative and intraoperative predictors of AKI have been identified. Nonetheless, no measure for AKI prevention reached a high level of recommendation, although hemodynamic monitoring and goal-directed fluid management may limit perioperative AKI. Cardiac surgery-related AKI and cardiopulmonary bypass-related AKI have been extensively evaluated and several preventive and treatment strategies have been developed. Open and endovascular surgery-related AKI have been compared and hydration is currently the only preventive strategy with a substantial level of efficacy. In addition, AKI in thoracic surgery, overlooked in the past, has been evaluated, showing that it frequently complicates postoperative course of patients undergoing elective lung cancer resection. Multi-hit mechanisms (ischemia, inflammation, toxins) co-act on patients' predisposition (susceptibility). A multi-step approach is probably necessary to limit the incidence and the severity of postsurgery AKI patients, such as careful risk stratification, adoption of preventive measures and goal directed intraoperative algorithms. The present review will summarize the current literature about the epidemiology of postoperative AKI focusing on patient-related and technical-related risk factors, outcome and prevention strategies in different groups of surgeries.

Prescription of dialysis in pediatric acute kidney injury

Renal replacement therapy (RRT) is the most effective way of managing severe acute kidney injury (AKI) in critically ill patients. RRT application in children is currently increasing due to the progressive rise of severity of critical illness in these patients. The burden of mortality in RRT children with AKI significantly outweights 50% of the dialized patients (depending also on the diagnosis and on the presence of multiple organ dysfunction). Many aspects of pediatric AKI requiring RRT are currently uncertain or have never been investigated. Whereas much of the clinical information applied to the adult patients is commonly reported to pediatric critically ill children, recently a significant evolution of RRT technology and novel research on pediatric dialysis warranted interesting evidence and important innovation in this field. In particular, it is currently a matter of debate how pediatric dialysis should be prescribed, when it is indicated and which modality should be utilized. This review will describe different modalities currently available for pediatric RRT, the main mechanisms of solute and water removal, standard and innovative technology specifically relased for neonatal dialysis, the most common prescriptions applicable to dialized children, indications to start and stop RRT.

Renal support

Renal support, intended as a refined and context-sensitive form of severe acute kidney injury management, might be achieved by administering renal replacement therapy with the correct timing and indication, correct prescription and, also, by the expertise and capacity of clinicians to tailor different RRTs to different patients. Furthermore, technical evolution and extended indications for extracorporeal treatments, currently allow the support of multiple organs, other than the isolated kidney failure. Unfortunately, current literature in the field of optimal management of severe acute kidney injury is controversial and lacks a standard of care. This review aims to describe the recent clinical, scientific and technical evolution of renal replacement therapy and the potential suggestive concept of multiple organ support therapy.

Fluid management in critically ill pediatric patients with congenital heart disease

Fluid balance management in pediatric critically ill patients is a challenging task, since fluid overload (FO) in the pediatric ICU is considered a trigger of multiple organ dysfunction. Pediatric patients with congenital heart disease (CHD) have several pre, intra and postoperative risk factors of derangements in fluid management. In particular, the smallest patients with acute kidney injury are at highest risk of developing severe interstitial edema, capillary leak syndrome and FO. Several studies previously showed a significantly higher percentage of FO among children with severe renal dysfunction requiring RRT, strongly associated with poor outcomes. For this reason, in children, priority indication is currently given to the correction of water overload. The present review will discuss recent literature addressing the issue of fluid balance in critically ill children with CHD, dosages, benefits and drawbacks of diuretic therapy, alternative diuretic/nephroprotective drugs currently proposed in the pediatric cardiac surgery setting. Monitoring of fluid balance will be reviewed. Specific modalities of pediatric extracorporeal fluid removal will be presented.

Small bowel faeces sign in patients without small bowel obstruction

AIM

To evaluate frequency and clinical relevance of the 'small bowel faeces' sign (SBFS) on computed tomography (CT) in patients with and without small bowel obstruction (SBO) presenting with acute abdominal or acute abdominal and flank pain.

METHODS

Abdominal CTs of consecutive patients presenting to the emergency department with abdominal or flank pain over a 6 month period were retrospectively reviewed by six radiologists, independently, for the presence of the SBFS. Examinations with positive SBFS were further evaluated in consensus by three radiologists, blinded to the final diagnosis. The small bowel was graded as non-dilated (<2.5 cm) and mildly (2.5-2.9 cm), moderately (3-4 cm) or severely (>4 cm) dilated. The location of SBFS and presence of distal small bowel collapse indicative of SBO was recorded. Imaging findings were subsequently correlated with the final diagnosis via chart review and compared between patients with and without SBO.

RESULTS

Of 1642 CT examinations, a positive SBFS was found in 100 (6%) studies. Of 100 patients with a positive SBFS, 32 (32%) had documented SBO. The remaining 68 patients had other non-obstructive diagnoses. SBFS was located in proximal, central, distal and multisegmental bowel loops in one (3.1%), eight (25.0%), 21 (65.6%) and two (6.3%) patients with SBO, and in zero (0%), 10 (14.7%), 53 (77.9%) and five (7.4%) of patients without SBO (p<0.273). The small bowel was non-dilated and mildly, moderately or severely dilated in one (3%), five (16%), 20 (62%) and six (19%) patients with SBO, and in 61(90%), seven (10%), zero (0%) and zero (0%) patients without SBO. Normal or mildly dilated small bowel was seen in all (100%) patients without SBO, but only in six (19%) of 32 patients with SBO (p<0.0001). Moderate or severe small bowel dilatation was seen in 26 (81%) patients with SBO (p<0.0001), but it was absent in patients without SBO. Distal small bowel collapse was found in 27 (84.4%) of 32 patients with SBO, but not in patients without SBO (p<0.0001). A combination of SBFS, moderate or severe small bowel distension and distal collapse was found in 23 (71.9%) patients with SBO (p<0.0001), but was not found in patients without SBO.

CONCLUSION

A SBFS is more frequent in patients presenting with acute abdominal/flank pain without bowel obstruction. When seen in association with moderate or severe small bowel dilatation, a SBFS is significantly more common in patients with SBO. When a SBFS is associated with normal or mildly dilated small bowel, the majority of patients have no bowel obstruction.

Informed consent for therapy and research in continuous renal replacement therapy: an international survey

OBJECTIVE

To study the approach of health care workers (HCW) to informed consent for therapy and research in the field of continuous renal replacement therapy (CRRT).

DESIGN

Administration of questionnaire.

SETTING

Two International Courses on Critical Care Nephrology (CCN) held in Vicenza and Melbourne.

PARTICIPANTS

Eight hundred and twenty one course participants.

RESULTS

We obtained 349 analysable questionnaires (42.5% of participants). Only 22.5% of responders always obtain informed consent for CRRT; 70.3% just inform patients/relatives without seeking consent, 7.1% never obtain informed consent. In ICU patients, informed consent is considered 'good, correct and feasible' for therapy and for research by only 13% and 27% of responders, respectively. Consent for clinical research obtained from the next of kin or legal guardian is considered good, correct and feasible' by 56.3% of respondents, while 39.1% believe that next of kin or legal guardians can not really make informed decisions. Finally, nearly half of responders think that present rules hamper research in ICU. For many questions, significant variability of responses was found according to profession, specialty and origin of responders.

CONCLUSIONS

In the field of CRRT, stated practice, beliefs and currently accepted ethical standards vary greatly according to profession, specialty and origin. A significant disagreement between what is widely promoted to be the 'correct' approach and what is currently done is evident.

Levobupivacaine versus racemic bupivacaine for spinal anaesthesia in orthopaedic major surgery

AIM

Levobupivacaine, a new local anaesthetic, has been recently introduced into clinical practice because of its lower toxic effects for heart and central nervous system. It has been already investigated in epidural and loco-regional techniques, but more has to be known regarding its characteristics in spinal anaesthesia. The aim of our study was to compare clinical and anaesthetic features of levobupivacaine and racemic bupivacaine when intrathecally administered in 60 patients undergoing major orthopaedic surgical procedures.

METHODS

Three ml of glucose-free levobupivacaine 0.5% (group L) or 3 ml of isobaric bupivacaine 0.5% (group B) were administered in 30 patients each. Sensory and motor blockades were evaluated by the pinprick test and a modified Bromage score, respectively. Vital parameters, postoperative VAS and rescue analgesia were recorded as well.

RESULTS

No statistically significant differences between groups were observed either in anaesthetic potencies or postoperative pain. Either heart rate or mean arterial pressure slightly decreased in both groups, with no preoperative significant differences. Nevertheless, spinal puncture was accompanied by severe hypotension and bradycardia in 2 patients of group B. In both cases, hemodynamics were promptly and successfully treated, with no sequelae.

CONCLUSIONS

In conclusion, levobupivacaine results a valid alternative to racemic bupivacaine for spinal anaesthesia, the latter remaining a cheap and effective local anaesthetic yet. Notwithstanding the complete absence of any significant hemodynamic complications in the patients of group L, further and larger studies are needed in order to assess if levobupivacaine is preferable to bupivacaine for minimizing the possible cardiovascular impact of spinal anaesthesia.

Management of fluid balance in CRRT: a technical approach

BACKGROUND

The possibility of making fluid balance errors during continuous renal replacement therapy has been identified since the beginning of this modality of treatment. The advent of automated machines has partially overcome this problem. Nevertheless, there are conditions and operation modes in which the potential for fluid balance errors is still present.

OBJECTIVE

To analyse fluid balance management in CRRT therapies across a range of currently marketed machine.

METHODS

The tests were conducted in vitro, utilizing saline solution for the blood circuit and regular dialysate/reinfusate for the dialysate/reinfusion circuit. The methodology used was based on the voluntary creation of a fluid balance error by altering the correct flow in the circuit of the different machines. Subsequently, the time for alarm occurrence and the threshold value for fluid balance error was evaluated. The alarm was overridden and the overall fluid error allowed by the machine was evaluated. Each machine was tested in conditions of different dialysate/filtrate flow rates and in different simulated treatment modalities.

RESULTS

Fluid balance errors can be easily avoided not only by a correct and careful adherence to the protocols of use of the current CRRT machines, but also by the compliance to prescriptions and programmed controls during therapy. Most importantly, if an alarm appears on the machine, one can try to override it without major problems; major problems may occur when multiple override commands are operated without identifying the problem and solving it adequately.

CONCLUSION

Machines seem to be designed with adequate safety features and accurate alarm systems. However, features and alarms can be manipulated by operators creating the opportunity for serious error. Physicians and nurses involved in prescription and delivery of CRRT should have precise protocols and defined procedures in relation to machine alarms to prevent major clinical problems.

[Rationale for the use of extracorporeal treatments for sepsis]

Sepsis is the leading cause of disability and mortality among critical patients; moreover, it causes high economic expenditures. Although very much is known about the pathophysiology of this condition and its mediators despite great investments directed to its control, mortality rates remain high. Recent treatment manuals emphasize the value of early goal-oriented therapy and also point to the high efficacy of activated protein C. Extracorporeal blood clearance may potentially become a new approach to treating this condition. There are reports on its positive clinical results that are likely associated with the effective removal of septic mediators. Human and animal studies, few and rather alike as they are, have yielded promising results. It is evident that the use of these procedures is justified; however, their efficiency in sepsis requires large-scale, correctly conducted studies.

Pulse high volume hemofiltration

The sepsis syndrome is the most common cause of acute renal failure and multiple organ dysfunction in critically ill subjects and continues to have an alarmingly high mortality. Normal immune homeostasis is interrupted by a complex storm of inflammatory mediators responsible for the deleterious effects. Extracorporeal blood purification techniques can confer benefits in sepsis by proven non-specific removal of these mediators (pro- or anti-inflammatory), and provide a logical and adequate approach to treat this syndrome. High volume hemofiltration (HVHF) has had the most dramatic effect conferring benefits in hemodynamics, reduction in vasopressor doses and improvement in survival. "Pulse HVHF" is the latest approach which may offer the most efficient results: a daily schedule of 6-8 hours followed by standard CVVH. This paper describes the rationale and potential of this technique. Reliability and tolerance of this technique and biological effects are described.

Continuous renal replacement technology: from adaptive devices to flexible multipurpose machines

OBJECTIVE

To review the evolution of technologies in the development of renal replacement therapies.

DATA SOURCES

Articles and published reviews on renal replacement therapies.

SUMMARY OF REVIEW

Continuous arterio-venous haemofiltration (CAVH) was the first continuous renal replacement technique capable of overcoming the traditional haemodialysis-related side effects, making possible the treatment of critically ill patients safely and with less physiological instability. The evolution of technology and the progress experienced in intensive care units (ICUs) has made it possible to start renal replacement therapy programs in the absence of a chronic dialysis facility or a trained nephrological team. Initial limitations and draw-backs of CAVH, stimulated the ICU staff to explore new avenues for better therapy. Extracorporeal therapies are today a routine experience in the ICUs: continuous renal replacement therapies are a broadly accepted treatment for acute renal failure. Furthermore, alternative indications for extracorporeal blood circulation (e.g. sepsis, liver failure, congestive heart failure, drug intoxications, hyperthermia, immuno-mediated syndromes) are becoming more and more popular. The ideal machine has yet to be completed, but progress has occurred and has opened a new era for critical care nephrology and the further expansion of blood purification technology in the ICU.

CONCLUSIONS

Technical advances in renal replacement therapies have increased their functionality (i.e. used in hepatic failure, sepsis, cardiac failure and immuno-mediated syndromes), are easier to operate and have less side-effects compared with their standard extracorporeal counterparts. Further improvements may see them become a routine part in the management of the critically ill patient.

Ultrafiltration in Patients with Hypervolemia and Congestive Heart Failure

Fluid overload may occur in patients with myocardial dysfunction and different clinical problems. Myocoardial dysfunction may be a consequence of heart dilatation with reduced contractility, ventricular stiffness with diastolic dysfunction or the consequence of myocardial injury or circulating myocardial depressant factors as seen in sepsis. In all cases, cardiac support can be achieved by the optimization of fluid balance, the reduction in organ edema and the restoration of desirable levels of pre- and afterload. Several reports have shown that myocardial elastance can improve after hemofiltration with restoration of adequate fluid balance. In such conditions, continuous extracorporeal therapy may result in remarkable cardiovascular stability with maintenance of hemodynamic parameters, including mean arterial pressure, heart rate and systemic vascular resistance. Such stability, which is achieved through the slow continuous ultrafiltration and continuous refilling of the intravascular volume from the interstitium, enables the stability of the circulating blood volume and the preservation of organ perfusion. This is also crucial for renal recovery during acute renal failure.

Extracorporeal treatments in sepsis: are there new perspectives?

Sepsis continues to provide a major challenge to clinicians. Despite vast advancements achieved in the understanding of its pathways and mechanisms, the incidence of sepsis is increasing and the mortality and morbidity rates remain high, generating a considerable burden to health budgets worldwide. Unfortunately, no definitive therapy yet exists that can successfully treat sepsis and its complications. At variance with targeting single mediators, therapeutic intervention aimed at the non-selective removal of pro- and anti-inflammatory mediators seems a rational concept and a possible key to successful extra-corporeal therapies. A further advantage may lie in the continuous nature of such therapy. With such continuous therapy, sequentially appearing peaks of systemic mediator overflow may be attenuated and persistently high plasma levels reduced. This theoretical framework is proposed as the underlying biological rationale for a series of innovative modalities in sepsis. In this editorial, we will review recent animal and human trials which lend support to this concept. We will also review the importance of treatment dose during continuous renal replacement therapy as a major factor affecting survival in critically ill patients with acute renal failure. We will also review novel information related to other blood purification techniques using largo pore membranes or plasma filtration with adsorbent perfusion. Although these approaches are still in the early stages of clinical testing, they are conceptually promising and might represent an important advance.

Importance of increased ultrafiltration volume and impact on mortality: sepsis and cytokine story and the role for CVVH

There is growing interest in extracorporeal blood purification therapies (EBPT) as adjuvants in the complex therapy of sepsis and multiple organ dysfunction syndrome (MODS). Nowadays the only routinely used purification technique is 'renal replacement therapy' (RRT) during acute renal failure (ARF), one of the almost inevitable and deadly components of MODS. RRT has been the first and still is the most utilised and effective type of EBPT. Evidence is growing about its ability to maintain homeostatic balance in critically ill patients, and specifically in septic patients with MODS. Clinical trials have been recently designed to modify or improve these therapies. In detail, the following issues have been currently addressed: effects on blood purification provided by different therapies, adequacy of prescription and delivery of therapy, toxins and solutes to be removed with these techniques. Based on these speculations we will briefly review the current understanding of these issues and the rationale for application of RRT in the intensive care unit (ICU). In particular, we will focus on the importance of increased ultrafiltration volume and its impact on mortality in the general ICU population and in septic patients.

Hemodynamic response to fluid withdrawal in overhydrated patients treated with intermittent ultrafiltration and slow continuous ultrafiltration: role of blood volume monitoring

Fluid overload may occur in patients with congestive heart failure, especially when there is associated acute renal failure. When the pharmacological approach is not sufficient to maintain the patient's fluid balance, extracorporeal therapies must be instituted. However, since the ultrafiltration rate may be faster than fluid refilling from the interstitial space, remarkable changes in the circulating blood volume may occur. This may finally result in further worsening of peripheral perfusion due to a significant drop in cardiac output. In order to prevent a fall in the circulating blood volume, slow continuous ultrafiltration (SCUF) should be employed instead of acute intermittent ultrafiltration (UF). To further improve the tolerance to extracorporeal ultrafiltration, the session can be driven by the relative blood volume change monitored on-line with adequate sensors and devices. We utilized one of these systems (Crit-Line, Hemametrics, USA) to compare the relative changes in blood volume during UF and SCUF in 22 patients with fluid overload. Variations in blood pressure were significantly greater with UF than with SCUF even in the presence of similar levels of fluid removal. The variations in blood pressure were paralleled by variations in blood volume, which were greater with UF than with SCUF. In conclusion, extracorporeal ultrafiltration can be used to control the fluid balance in congestive heart failure, but it is advisable to prescribe low ultrafiltration rates over an extended period of time. The use of on-line blood volume monitors can be of further help in improving tolerance and the hemodynamic response.

A novel approach to the treatment of chronic fluid overload with a new plasma separation device

Many patients with congestive heart failure suffer at some point in their therapy from severe fluid overload, and a significant proportion of patients become unresponsive to diuretic drug therapy. In this paper, we propose a new experimental approach to plasma purification and the treatment of severe fluid overload in acute care patients. Plasma can be extracted directly from the patient through an intracorporeal catheter temporarily placed within the inferior vena cava. Plasma separation is accomplished through a proprietary membrane placed on the tip of the catheter. A simple circuit performs plasma removal. The extracted plasma is then available for any type of treatment before being returned to the patient via a second lumen in the same catheter. Plasma flow rates between 3 and 8 ml/min have been achieved and animal tests led to the removal of more than 2,000 ml of plasma water in 24 h. The current varieties of blood purification or ultrafiltration techniques employ extracorporeal extraction of blood from the patient in order to perform treatment. Removal of the cellular component in the extracorporeal fluid circuit may reduce the current problems associated with extracorporeal circuits, such as cellular lysis and viscosity-related problems. Plasma treatment is already successfully performed in a variety of therapies, including renal replacement therapies and plasmapheresis. The therapy proposed here may extend the utility of plasma treatment to the acute cardiology patient. The system could become an important complementary therapy for patients with congestive heart failure for whom classic methods of treatment have failed or simply are not available.

Extracorporeal ultrafiltration for the treatment of overhydration and congestive heart failure

Fluid overload may occur in patients with congestive heart failure. Under normal conditions, this is treated with inotropic support and diuretics. However, when diuretics fail, fluid removal becomes uncontrolled and other therapeutic options must be undertaken. Extracorporeal ultrafiltration is a possible solution to restore a status of fluid balance close to normal. Several new technologies have made ultrafiltration available today in all centers and easy to be instituted. Acute isolated schedules of ultrafiltration may, however, be too aggressive and result in severe hemodynamic instability. For this reason, continuous extracorporeal techniques have been applied in such patients and the therapy is generally carried out with success. Excellent hemodynamic stability, a good cardiovascular response and often diuresis restoration are the most common effects encountered using continuous forms of extracorporeal fluid removal. The potential for a home-based application of these techniques represents a further stimulating concept to be investigated.

Importance of increased ultrafiltration volume and impact on mortality: sepsis and cytokine story and the role of continuous veno-venous haemofiltration

While in end-stage renal disease dialysis dose correlates with morbidity and mortality, this correlation is less evident in acute renal failure. In spite of a poor literature in the field, a few recent papers seem to suggest that an increase in treatment dose may result in an improved outcome of critically ill patients affected by acute renal failure. This improvement appears to plateau at a certain level of dialysis dose in the general population while, in septic patients, the correlation between treatment dose and outcome continues linearly. These results suggest that, while the 'renal dose' of renal replacement therapy has a threshold beyond which further improvements cannot be expected, the 'septic dose' of renal replacement therapy is probably higher and may provide benefits beyond simple blood purification from uremic toxins. This approach is in agreement with the recently proposed 'peak concentration hypothesis', which suggests that sepsis may derive from a complete derangement of the immunological response, featuring simultaneous peaks of pro- and anti-inflammatory mediators. This would explain the systemic inflammatory syndrome and the cell hyporesponsiveness of the septic patient and, at the same time, would explain the beneficial effects of new therapies such as high volume hemofiltration, coupled plasmafiltration adsorption and dialysis with hyperpermeable membranes. These therapies could be able to reduce the peaks of the pro- and anti-inflammatory substances circulating during the syndrome, leading to a less severe degree of inflammation and immunodepression.

Continuous renal replacement therapy in critically ill patients

Acute renal failure is an evolving syndrome in which new pathogenetic mechanisms have recently been elucidated. The evolution of the field of haemodialysis has led to a parallel development in the therapeutic approach to patients suffering from this syndrome. In particular, acute renal failure is more frequently seen as part of a more complex syndrome, defined as multiple organ failure. In this clinical setting, patients are almost inevitably confined to intensive care units and sepsis is a frequent underlying mechanism of organ failure. The use of new devices and new machines, together with a better understanding of the underlying mechanisms of solute and water removal, have allowed us to achieve higher levels of efficiency and clinical tolerance during artificial renal replacement therapy. The first objective has been reached by increasing the automation of the extracorporeal circuits and the operational levels of the different techniques; the second has been achieved by means of a new generation of monitoring techniques and new machines equipped with specific interfaces and alarms. This progress has made continuous forms of renal replacement (CRRT) possible and easy to perform without major problems or complications. The most promising and effective options for treating acute renal failure in critically ill patients are today offered by continuous renal replacement therapies. Classic indications, but also alternative non-renal indications, have been proposed for these techniques. The most advanced indication is the multiple organ dysfunction occurring in septic patients. The possible removal of proinflammatory mediators may permit a blockade of the systemic inflammation, a modulation of the altered immune response in these patients, and it may lead to a partial or total restoration of the lost homeostasis.

[Peridural analgesic therapy in orthopedic surgery: comparison of ropivacaine and bupivacaine]

The aim of our study was to compare the efficiency of ropivacaine and bupivacaine, in epidural administration, in postoperative analgesia. 20 patients, undergone knee surgery, in epidural anaesthesia (bupivacaine 0.5%-2 mg/Kg-1 administered in level L3L4), was divided into 2 groups (10 each one) and the local anaesthetics in study was administered by epidural catheter with an elastomeric pump: A (ropivacaine 0.15%) and B (bupivacaine 0.15%). The results demonstrate that ropivacaine is better than bupivacaine to keep a check on analgesia in postoperative pain.

[Use of mivacurium in orthopedic surgery: comparison of 2 different-dose inductions]

The aim of our study was to evaluate the efficiency and safety of mivacurium, comparing two dose-induction in patients undergone a minor orthopaedic surgery. 30 patients were divided into two groups and mivacurium were administered at the dose of 0.15 mg Kg-1 and 0.20 mg Kg-1 respectively. The results confirmed its efficiency in short surgery. Mioresolution was excellent only in the second group (0.20 mg Kg-1) despite an histamine-related blood pressure reduction.

[Use of ropivacaine in axillary brachial plexus block]

The aim of the study was to evaluate the efficiency and safety of ropivacaine, in comparison with bupivacaine, in axillary brachial plexus block. 24 patients, undergoing upper limb surgery, was divided into 2 homogeneous groups and the local anaesthetics was administered: A (ropivacaine 0.75%, 25 ml; total dose 187.5 mg) and B (bupivacaine 0.5%, 25 ml; total dose 125 mg). The axillary plexus block was executed with the help of an electrostimulator. The results show that using ropivacaine the onset-time is lower and the duration of sensory and motor block is higher than using bupivacaine. In conclusion we can affirm that ropivacaine is a new step in local anaesthetic field.