Mitigating Hypovolemia-Induced Miscalibration of Photoplethysmogram-Derived Blood Pressure

Pulse transit time (PTT) is a hemodynamic indicator that may be obtained non-invasively using photoplethysmogram (PPG) signals for continuous blood pressure (BP) monitoring. Among the most promising applications of this technology are military and civilian trauma cases, where reduced blood volume due to hemorrhage, or absolute hypovolemia, is the leading preventable cause of death. However, the drawback of this method is that it requires calibration for each patient; additionally, changes in physiological state may affect PTT calibration. In this work, a porcine model (n = 6) was used to demonstrate that changes in blood volume lead to miscalibration of PTT for BP estimation. To mitigate hypovolemia-induced miscalibration, this work first defines a template-based signal quality index (SQI) for characterizing the morphology of PPG signals; it is then shown that the subject-specific calibration of SQI to BP is more robust to changes in blood volume than PTT. Though changes in PPG signal quality are not necessarily specific to changes in BP, these results suggest that PPG-based monitoring systems may benefit from incorporating morphological information for cuffless BP estimation in trauma settings.

Management of delayed cerebral ischemia after subarachnoid hemorrhage

For patients who survive the initial bleeding event of a ruptured brain aneurysm, delayed cerebral ischemia (DCI) is one of the most important causes of mortality and poor neurological outcome. New insights in the last decade have led to an important paradigm shift in the understanding of DCI pathogenesis. Large-vessel cerebral vasospasm has been challenged as the sole causal mechanism; new hypotheses now focus on the early brain injury, microcirculatory dysfunction, impaired autoregulation, and spreading depolarization. Prevention of DCI primarily relies on nimodipine administration and optimization of blood volume and cardiac performance. Neurological monitoring is essential for early DCI detection and intervention. Serial clinical examination combined with intermittent transcranial Doppler ultrasonography and CT angiography (with or without perfusion) is the most commonly used monitoring paradigm, and usually suffices in good grade patients. By contrast, poor grade patients (WFNS grades 4 and 5) require more advanced monitoring because stupor and coma reduce sensitivity to the effects of ischemia. Greater reliance on CT perfusion imaging, continuous electroencephalography, and invasive brain multimodality monitoring are potential strategies to improve situational awareness as it relates to detecting DCI. Pharmacologically-induced hypertension combined with volume is the established first-line therapy for DCI; a good clinical response with reversal of the presenting deficit occurs in 70 % of patients. Medically refractory DCI, defined as failure to respond adequately to these measures, should trigger step-wise escalation of rescue therapy. Level 1 rescue therapy consists of cardiac output optimization, hemoglobin optimization, and endovascular intervention, including angioplasty and intra-arterial vasodilator infusion. In highly refractory cases, level 2 rescue therapies are also considered, none of which have been validated. This review provides an overview of current state-of-the-art care for DCI management.

AISF-SIMTI Position Paper: The appropriate use of albumin in patients with liver cirrhosis

The use of human albumin is common in hepatology since international scientific societies support its administration to treat or prevent severe complications of cirrhosis, such as the prevention of post-paracentesis circulatory dysfunction after large-volume paracentesis and renal failure induced by spontaneous bacterial peritonitis, and the treatment of hepatorenal syndrome in association with vasoconstrictors. However, these indications are often disregarded, mainly because the high cost of human albumin leads health authorities and hospital administrations to restrict its use. On the other hand, physicians often prescribe human albumin in patients with advanced cirrhosis for indications that are not supported by solid scientific evidence and/or are still under investigation in clinical trials. In order to implement appropriate prescription of human albumin and to avoid its futile use, the Italian Association for the Study of the Liver (AISF) and the Italian Society of Transfusion Medicine and Immunohaematology (SIMTI) nominated a panel of experts, who reviewed the available clinical literature and produced practical clinical recommendations for the use of human albumin in patients with cirrhosis.

[GOAL-TARGET INFUSION THERAPY BASED ON NONINVASIVE HEMODYNAMIC MONITORING ESCOO]

We described our experience in using the new noninvasive hemodynamic monitoring (esCCO), which allowed recording most important parameters of heart capacity. Infusion therapy during laparoscopic operations might be based on dynamic of systolic blood volume. This functional approach can be used for evaluation of heart reaction on bolus fluid load, to optimike volemic status in situations associated with dynamical blood circulation changes. We compared intraoperative infused fluid volumes, calculated by traditional approach and by target approach. The obtained results had significant differences among groups, and didn't correspond with "liberal" and "restrictive" strategy for infusion therapy.

Monitoring needs and goal-directed fluid therapy within an enhanced recovery program

Patients having major abdominal surgery need perioperative fluid supplementation; however, enhanced recovery principles mitigate against many of the factors that traditionally led to relative hypovolemia in the perioperative period. An estimate of fluid requirements for abdominal surgery can be made but individualization of fluid prescription requires consideration of clinical signs and hemodynamic variables. The literature supports goal-directed fluid therapy. Application of this evidence to justify stroke volume optimization in the setting of major surgery within an enhanced recovery program is controversial. This article places the evidence in context, reviews controversies, and suggests implications for current practice and future research.

[Optimization of infusion therapy in patients with ovarian cancer]

We investigated the clinical observations and the results of a comprehensive survey of 70 patients with ovarian cancer stage III-IV aged 30 to 70 years with the presence of endotoxemia. Integral assessment of prognosis and severity of the condition was performed according to SAPS II and SOFA. Infusion program included a preliminary correction of hypovolemia prior to surgery on the operating table in equal parts, HES and balanced crystalloid solutions, with in- creased infusion of 15% of blood volume based on the method of anesthesia. In the early postoperative period, infusion programs were complemented by various embodiments of metabolic correction. Patients of group-1 (n = 35) received remaxol in a dose of 800 mI/day. Patients of group-2 (n = 35) received ademethionine (heptral) 800 mg/day. Analysis of the results revealed that premorbid background in patients with ovarian cancer stage III-IV was characterized by hypovolemia, phenomena hepatopathy, and endotoxemia, and mixed forms of hypoxia of varying severity. Differentiated approach to the choice of pathogenesis-based perioperative infusion according to premorbid condition, anesthesia and blood loss contributed to the elimination of hypovolemia, favored efficient oxygen delivery and consumption, the ade- quacy of tissue oxygenation. Remaxol inclusion in the perioperative infusion programs in patients with ovarian cancer enhanced their clinical efficiency, reduced cytolytic and cholestatic syndromes, recovered of protein and synthetic liver function, reduced the appearance of mixedforms of hypoxia and endogenous intoxication.

Is it time to rethink cord management when resuscitation is needed?

A newborn who receives a placental transfusion at birth, either from cord milking or delayed cord clamping, obtains about 30% more blood volume than the newborn whose cord is cut immediately. Receiving an adequate blood volume from placental transfusion at birth may be protective for the distressed neonate as it prevents hypovolemia and can support optimal perfusion to all organs. New research shows that ventilating before clamping the umbilical cord can reduce large swings in cardiovascular function and help to stabilize the newborn. Hypovolemia, often associated with nuchal cord or shoulder dystocia, may lead to an inflammatory cascade and subsequent ischemic injury. A sudden unexpected neonatal asystole at birth may occur from severe hypovolemia. The restoration of blood volume is an important action to protect the hearts and brains of these neonates. Current protocols for resuscitation imply immediate cord clamping and the care of the newborn away from the mother's bedside. We suggest that an intrapartum care provider can achieve placental transfusion for the distressed neonate by milking the cord several times or resuscitating the neonate at the perineum with an intact cord. Milking the cord can be done quickly within the current Neonatal Resuscitation Program guidelines. Cord blood gases can be collected with delayed cord clamping. Bringing the resuscitation to the mother's bedside is a novel concept and supports an intact cord. Adopting a policy for resuscitation with an intact cord in a hospital setting will take concentrated effort and team work by obstetrics, pediatrics, midwifery, and nursing.

[A propose to suspend the use of hydroxyethyl starch for fluid resuscitation in shock phase of severe burns]

Based on the result of randomized controlled trials and meta-analysis recently, the infusion of hydroxyethyl starch (HES) was not shown to over match routine crystalline solution in exerting resuscitation effect against hypovolemia of patients with burn shock, severe systematic infection, or other critical conditions, on the other hand, it may induce renal toxicity and other toxic and side effects. Since the pathological mechanism underlying hypovolemia during shock phase after burn is similar to that of severe systemic infection, we propose to suspend the use of HES for fluid resuscitation during the shock phase of severe burn until further elucidation.

Does bioimpedance analysis or measurement of natriuretic peptides aid volume assessment in peritoneal dialysis patients?

Cardiovascular mortality remains the commonest cause of death for peritoneal dialysis patients. As such, preventing persistent hypervolemia is important. On the other hand, hypovolemia may potentially risk episodes of acute kidney injury and loss of residual renal function, a major determinant of peritoneal dialysis technique survival. Bioimpedance has developed from a single-frequency research tool to a multi-frequency bioelectrical impedance analysis readily available in the clinic and capable of measuring extracellular, intracellular, and total body water. Similarly, natriuretic peptides released from the heart because of myocardial stretch and increased intracardiac volume have also been variously reported to be helpful in assessing volume status in peritoneal dialysis patients. The question then arises whether these newer technologies and biomarkers have supplanted the time-honored clinical assessment of hydration status or whether they are merely adjuncts that aid the experienced clinician.

[Clinical effectiveness of the infusion therapy under control of the transesophageal dopplerography in acute period of severe combined trauma]

In 72 patients with combined trauma the impact of volume and consistence of infusion therapy on severity of the disease, frequency and severity of infectious complications, duration of MV and ICU stay was assessed. The patients were divided into 2 groups depending on the volemic status control method and infusion algorithm. The main group (35 patients) was controlled by transesophageal dopplerography Cardio Q apparatus ("Deltex Medical", GB) and the infusion therapy was carried out under the control of stroke volume and Ftc. In the control group (37 patients) the volemic status was assessed clinically: BP, CVP, HR, diuresis. The volume of the infusion therapy during the first 12 hours in the main group was significantly higher than in the control group which proved that patients were suffering from hypovolemia, which was not diagnosed by traditional clinical criteria. The ICU stay in the main group was significantly shorter compared to the control group 15.3 +/- 8.2 and 29.5 +/- 10.4 days respectively. Infectious complications occurred in 12 patients out of 35 in main group and 25 out of 37 in the control group. The conclusion of this study is that infusion therapy control with central hemodynamic parameters can shorten the MV time and ICU stay an lower the rate of infectious complications in patients with combined trauma. A mortality decrease in patients with transesophageal dopplerography controlled infusion is not shown.

[Clinical application of the plasma substitutes in patients with postoperative complications after surgeries for brain meningioma]

The issues on optimization of the restoration treatment of patients, suffering the brain meningioma, were discussed, basing on analysis of 498 observations. Tactics of the patients management in noncomplicated, complicated and severe course of postoperative period is adduced. The indices of survival and lethality, peculiarities of the infusion therapy were analyzed. The role of plasm-restituting preparations was demonstrated in complicated course of postoperative period. Rational complex approach to the restoration measures and intensive therapy conduction promotes the treatment efficacy raising, the patients fair quality of life securing in the brain meningioma in postoperative period.

[Albumin and artificial colloids for massive bleeding]

Rapid and massive bleeding has to be counteracted by efficient volume restoration against rapid loss of intravascular volume. There are two phases of volume management for massive bleeding, uncontrolled phase and controlled phase. During initial uncontrolled phase, rapid infusion of crystalloid with RCC (red cell concentrate) is the first choice of volume management to prevent shock and profound decline of hemoglobin level. After shifting to the next controlled phase, artificial colloids and RCC become the next choice for efficient volume restoration. Although albumin has not been proven to improve prognosis in clinical studies, anti-inflammatory effect could be expected. Albumin infusion may be followed in this phase, and also albumin concentrate may be beneficial to reduce subsequent tissue edema due to massive infusion of crystalloid and artificial colloid. A new generation of hydroxyethyl starch is a promising blood substitute, designed with minimum side effect. Although renal damage especially in septic patient and coagulation disorder are theoretically suspected, beneficial effect as volume expansion overwhelms these stochastic side effects. Since the side effect depends on the dose and how much it remains in the body, a purposeful use during volume expansion phase should be recommended.

[Postoperative infusion therapy in children]

The study investigates the influence of Voluven 6% and HAES-steril 10% on the hemodynamics and organism water balance of 40 children from 3 months to 17 years of age, which were divided into two groups according to the type of the administered colloid. It is acquired that infusion of colloids with 1:3 ratio compared to crystalloids in general volume of infused liquids (Voluven 6% in the dose of 5 ml/kg/hour in case of median blood loss of 15% of the total circulating blood volume during two hour long surgery and HAES-steril 10% in the dose of 4 ml/kg/hour in case of the blood loss up to 25% of TCBV) allows to effectively neutralize hemodynamic changes based upon administration of anesthetic agents and intraoperative fluid loss. While administration of Voluven 6% is accompanied by significant, statistically accurate decrease of lower limb impedance, which indicates the increased amount of water in them, HAES-steril 10% administration leads to redistribution of water in the body segments with its predominant significant increase in the torso.

[Role of 6% hydroxyethylstarch 130/0.4 and furosemide in the treatment of acute pancreatitis]

This study was conducted to observe the effects of intravenously administered 6% hydroxyethylstarch 130/ 0.4 solution and furosemide on the outcome of acute pancreatitis patients. Patients admitted to our center from October 16, 2007 through August 31, 2009 were given intravenous infusions of 6% hydroxyethylstarch 130/0. 4 solution (1 000-2 000 ml administered for an adult) soon after admission. At the same time, furosemide was administered as intravenous bolus, trying to maintain a fluid balance. The dose level of hydroxyethylstarch was gradually lowered from the second day after admission. A total of 135 patients (54% of patients with a Ranson's score > or = 3 and 61% with a Balthazar CT score > or = D) were treated with our protocol. Only 4% and 7% patients developed pancreatic and systemic complications respectively; only 1 patient underwent necrosectomy. The in-hospital mortality rate was 4%. It was estimated that, on the average, 18. 3% of blood volume was lost on admission. Our study suggest that intravenously administered 6% hydroxyethylstarch 130/0. 4 solution and furosemide might be beneficial for patients with acute pancreatitis. Plasma extravasation is a central event of acute pancreatitis. The reversal of hypovolemia is crucial for the success in treatment of acute pancreatitis.

Canine tactical field care. Part two--Massive hemorrhage control and physiologic stabilization of the volume depleted, shock-affected, or heatstroke-affected canine

Military and law enforcement agencies have seen a dramatic increase in the utilization of military working dogs (MWDs) and working canine officers, respectively both at home and in foreign deployments. Due to the fact that professional veterinary care is often distant from internal disaster or foreign deployment sites, the military medic, police tactical medic, or other first-response medical care providers may be charged with providing emergency or even basic, non-emergency veterinary care to working canines. The medical principles involved in treating canines are essentially the same as those for treating humans; however, the human healthcare provider needs basic information on canine anatomy and physiology, and common emergency conditions, in order to provide good basic veterinary care until a higher level of veterinary care can be obtained. This article represents the second in a series designed to provide condensed, basic veterinary information on the medical care of working canines, including police canines, federal agency employed working canines, and search-and-rescue dogs, in addition to the MWD, to those who are normally charged with tactical or first responder medical care of human patients. This article focuses on diagnosing and treating some of the more common high-mortality conditions affecting canines in the field including massive hemorrhage, volume-depletion, shock, and heatstroke.

[Systemic hemodynamic disorders in critically ill patients with intracranial hemorrhages]

The paper analyzes systemic hemodynamic disorders in 45 victims of severe brain injury and patients with nontraumatic intracranial hemorrhages. The incidence of hypovolemia in patients with nontraumatic intracranial hemorrhages and victims of severe brain injury is 65.4% and 73.7%, respectively. Infusion therapy based on the estimation of routine hemodynamic parameters (blood pressure, heart rate, central venous pressure, daily fluid balance) could not prevent hypovolemia in the examinees and caused a high rate of sympathomimetic use in uncorrected volemic states.

Pathophysiology and clinical implications of peroperative fluid management in elective surgery

The purpose of this thesis was to describe pathophysiological aspects of perioperative fluid administration and create a rational background for future, clinical outcome studies. In laparoscopic cholecystectomy, we have found "liberal" crystalloid administration ( approximately 3 liters) to improve perioperative physiology and clinical outcome, which has implication for fluid management in other laparoscopic procedures such as laparoscopic fundoplication, laparoscopic repair of ventral hernia, hysterectomy etc., where 2-3 liters crystalloid should be administered based on the present evidence. That equal amounts of fluid caused adverse physiologic effects in healthy volunteers indicates that addition of the surgical trauma per se increases fluid requirements. Volume kinetic analysis applied 4 hours postoperatively was not able to detect the presence of either overhydration or hypovolemia regardless of the administered fluid volume intraoperatively. In knee arthroplasty a approximately 4 vs. approximately 2 liters crystalloid-based fluid regimen lead to significant hypercoagulability (although with unknown clinical implications), but no over-all differences in functional recovery. Dehydration caused by bowel preparation leads to functional hypovolemia and the deficits should be corrected, in particular in elderly patients, where preoperative intravenous fluid substitution of approximately 2-3 liters crystalloid is recommended. We did not find thoracic epidural anesthesia to be accompanied by intravascular fluid mobilization. In major (colonic) surgery with a standardized multimodal rehabilitation regimen, over-all functional recovery was not affected with a "liberal" ( approximately 5 liters) vs. "restrictive" 1.5 liter crystalloid-based regimen, however based on three anastomotic leakages in the "restrictive" group, it may be hypothesized that a too "restrictive" fluid administration strategy could be detrimental in patients with anastomoses and need further evaluation. A systematic review concluded that present evidence does not allow final recommendations on which type of fluid to administer in elective surgery. Based on the current evidence, administration of < 5 liters intravenous fluid without specific indication in major surgical procedures should be avoided, while administration of < 1.5 liters in patients with anastomoses may not be recommended, an issue needing clarification in large-scale clinical studies. Finally, we have demonstrated that the conduction of double-blinded randomized trials on fluid management with postoperative outcomes is feasible.

[Hemodynamic efficacy of modified gelatin in patients with acute blood loss and sepsis]

The paper presents the results of a clinical trial using the new modified gelatin-based drug hemofusin to correct dyshidria in patients with blood loss and sepsis. Based on the findings, the authors provide evidence for the high clinical efficacy of this drug and the expediency of its incorporation into a complex of infusion therapy in this patient contingent.

[Perioperative infusion therapy in children]

A volume replacement therapy compensates a reduced intravascular volume to stabilize and maintain hemodynamics and vital signs. For this therapy, a physiologically-based solution comprising both, osmotic and colloid osmotic components, should be administered. The basic requirement for a sufficient fluid replacement and volume resuscitation therapy in children are the profound and special knowledge of the physiological and pathophysiological interactions in water balance and electrolyte metabolism in childhood, the pharmacology of the applied solutions and the adequate monitoring of this fluid and volume replacement therapy. Wrong dosages and side effects are reasons for a negative postoperative outcome in children.

[Impact of preoperative levosimendan therapy on the volemic status and vascular tone of patients with chronic heart failure during anesthesia]

The impact of preoperative levosimendan therapy on the volemic status and vascular tone was studied in patients with chronic heart failure (CHF) during anesthesia and the ways of correcting the occurring changes were defined. The study included 21 patients with CHF in the presence of dilated cardiomyopathy, who underwent mitral valve replacement and tricuspid valvoplasty. Group 1 patients (n = 11) were given levosimendan (Simdax) in a dose of 0.05-0.1 mg/kg x min 2 days prior to surgery; Group 2 (n = 10) was control. Central hemodynamics was monitored by the transpulmonary thermodilution technique (PiCCO-Plus, Pulsion Medical System). Intraoperative monitoring of microcirculation was made using a laser microcirculation analyzer. It has been established that the preoperative administration of levosimendan causes an increase in stroke index at critical surgical stages. With the use of levosimendan, peripheral microcirculation improves and nutritional blood flow increases. The preoperative use of levosimendan causes a reduction in the tone of resistance vessels during anesthesia, which can require vasopressor support in the postperfusion period; a levosimendan-induced decrease in preload requires infusion correction of relative hypovolemia.

[Target-oriented infusion therapy in patients during myocardial revascularization]

The paper analyzes goal-oriented infusion therapy used during myocardial revascularization on the working heart. Forty-seven patients with coronary heart disease were examined. Group 1 (control) (n = 20) received standard infusion therapy (a combination of colloids and crystalloids (1:1) at a rate of 6-7 ml/kg/h, by being oriented to indices, such as heart rate, blood pressure, central venous pressure, and diuresis rate. In group 2, an anesthetist was oriented to central hemodynamic parameters during infusion therapy. In addition, the patients of this group underwent the 45 degrees passive leg raising test. In this group, a volume load was done at the beginning of an operation until the maximum possible SV resulted from increased preload (global end-diastolic volume index). The goal of infusion therapy throughout the operation was to maintain these values of the latter index. Goal-oriented infusion therapy, the purpose of which was to determine and maintain the individual optimal values of preload, was found to minimize hemodynamic disorders at surgery and to reduce the frequency of use of cardiotonic agents and the duration of artificial ventilation.

[Effect of volemic status on brain oxygenation and metabolism in patients with intracranial hemorrhages]

The paper analyzes the impact of the volemic status and its correction on systemic hemodynamic parameters (transpulmonary thermodilution PiCCO plus technique), the value of intracranial pressure and the biochemical composition of brain interstitial fluid (tissue microdialysis) in the affected and conditionally intact hemisphere in 8 patients with intracranial hemorrhages and a reduced awakening level up to 4-8 scores by the Glasgow coma scale. It has been shown that in patients with significant metabolic disturbance in the involved hemisphere, hypovolemia correction using hydroxyethyl starch 130/0.4 is accompanied by activated oxidative phosphorylation and a lower lactate/pyruvate ratio, without changing the of blood pressure and increasing pulmonary extravascular water.

[Evaluation of the effectiveness and safety of synthetic colloid solutions in the treatment of severe abdominal sepsis: a randomized comparative study]

Infusion therapy, surgical debridement of an infection focus, and antimicrobial therapy are basic treatments for severe sepsis. At the same time there are no uniform guidelines on how to choose fluids for infusion therapy. The results of individual studies serve as the basis for refusing the use of synthetic colloid agents in the therapy of severe sepsis. The presented multicenter, randomized comparative study has evaluated different synthetic colloid solutions in early targeted therapy for severe sepsis. Evidence is provided for the identical effectiveness of the compared solutions in correcting hypovolemia and stabilizing hemodynamics in patients with severe sepsis and septic shock.

Autologous blood donation in total knee arthroplasties is not necessary

BACKGROUND

This study intends to prove the hypothesis that preoperative autologous blood donation in total knee arthroplasties (TKA) is dispensable.

PATIENTS AND METHODS

The study comprises a prospective analysis of 81 consecutive TKA without preoperative autologous blood donation (AB-donation). Guidelines for blood retransfusion were used. Surgery, as well as the pre- and postoperative procedures were identical for each patient. In the analysis of the data, the consecutive TKAs were divided into patients who were eligible for preoperative autologous blood donation (group 1, n = 46) and those with relevant risk factors not permitting preoperative autologous blood donation (group 2, n = 35).

RESULTS

None of the patients in group 1 needed a blood transfusion. 14 of 35 patients in group 2 needed an allogenic blood transfusion.

INTERPRETATION

Total knee arthroplasty can be managed without preoperative AB-donation if it is performed using a tourniquet, if a postoperative collection and direct retransfusion system is used for the wound blood, and if the transfusion algorithm is defined according to compulsory and practical guidelines.

[Perioperative fluid management: an analysis of the present situation]

Optimal perioperative fluid management is still controversial. Besides well known perioperative hypovolaemia, hypervolaemia has an influence on perioperative morbidity and mortality, particularly with regard to the patient's medical history, a reduced cardiac and pulmonal function and the operation itself. The concepts of preoperative, intraoperative and postoperative fluid administration are neither adequately validated, nor sufficiently integrated into a perioperative concept. At the present, moderate fluid administration to improve preoperative and postoperative outcome is safe in minor or medium surgical procedures. High-risk surgical patients benefit from a time-oriented or/and goal-oriented monitored fluid therapy. In the past only little attention has been concentrated on postoperative fluid management, but may be stimulated by the new concepts of fast track surgery.

[Infusion solutions of gelatin derivates]

Besides crystalloids, colloids are used for the treatment of hypovolemia and shock. They are high-molecular-weight proteins of bovine origin with properties of more rapid replacement of circulating blood volume. Iso-oncotic character provides the volume effect (approximately equal to 100%) close to the volume intravenously infused with the duration of action for 2-4 hours. Gelatin solutions are excreted with urine and feces in unchanged form without prolonged fixation in organism. Even in case of acute renal failure, gelatin peptides do not accumulate due to increased activity of proteolytic enzymes; therefore, they are the first-choice colloids. Gelatin solutions do not change coagulation as other colloids; just they may cause hemodilution as crystalloids do, so they are safe in case of hemorrhage and thrombocytopenia. There is a decreased risk of bleeding when gelatin solutions are used in surgery as compared with other colloids; in addition, they protect from hypotension due to vasodilatation in epidural or spinal analgesia. Gelatin solutions may cause compensatory hyperemia and increase of cardiac output, cardiac index, myocardial contractility, mean arterial blood pressure, and diuresis; in addition, oxygen delivery to the tissues improves. The dosage depends on clinical condition of a patient, and it is suggested to be 100-2000 mL and even more, for isovolemic hemodilution--20 mL/kg of body weight. Adverse reactions such as anaphylactoid or anaphylactic to gelatin derivates are rare and similar to other colloids.

[Tactics of infusion therapy in the acute period of intracranial hemorrhages]

The paper deals with the determination of infusion therapy tactics in critically ill patients with intracranial hemorrhages on the basis of invasive measurements of systemic hemodynamics. The routine hemodynamic parameters (blood and central venous pressures, heart rate) are noted to fail to assess the volemic status of the patients in full. Unlike the use of colloidal solutions, infusion therapy with physiological sodium chloride is not shown to correct systemic hemodynamics. It has been ascertained that in acute intracranial hemorrhages, infusion therapy with crystalloidal solutions leads to impaired pulmonary gas exchange and increased pulmonary extravascular fluid and the use of a combination of crystalloidal solutions and a colloidal agent in a 1:1 ratio can correct the volemic status of the patients and is not followed by lung dysfunctions.

Respiratory variations in aortic blood flow predict fluid responsiveness in ventilated children

OBJECTIVE

To investigate whether respiratory variations in aortic blood flow velocity (DeltaVpeak ao), systolic arterial pressure (DeltaPS) and pulse pressure (DeltaPP) could accurately predict fluid responsiveness in ventilated children.

DESIGN AND SETTING

Prospective study in a 18-bed pediatric intensive care unit.

PATIENTS

Twenty-six children [median age 28.5 (16-44) months] with preserved left ventricular (LV) function.

INTERVENTION

Standardized volume expansion (VE).

MEASUREMENTS AND MAIN RESULTS

Analysis of aortic blood flow by transthoracic pulsed-Doppler allowed LV stroke volume measurement and on-line DeltaVpeak ao calculation. The VE-induced increase in LV stroke volume was >15% in 18 patients (responders) and <15% in 8 (non-responders). Before VE, the DeltaVpeak ao in responders was higher than that in non-responders [19% (12.1-26.3) vs. 9% (7.3-11.8), p=0.001], whereas DeltaPP and DeltaPS did not significantly differ between groups. The prediction of fluid responsiveness was higher with DeltaVpeak ao [ROC curve area 0.85 (95% IC 0.99-1.8), p=0.001] than with DeltaPS (0.64) or DeltaPP (0.59). The best cut-off for DeltaVpeak ao was 12%, with sensitivity, specificity, and positive and negative predictive values of 81.2%, 85.7%, 93% and 66.6%, respectively. A positive linear correlation was found between baseline DeltaVpeak ao and VE-induced gain in stroke volume (rho=0.68, p=0.001).

CONCLUSIONS

While respiratory variations in aortic blood flow velocity measured by pulsed Doppler before VE accurately predict the effects of VE, DeltaPS and DeltaPP are of little value in ventilated children.

Perioperative fluid management: comparison of high, medium and low fluid volume on tissue oxygen pressure in the small bowel and colon

BACKGROUND AND OBJECTIVE

Insufficient blood flow and oxygenation in the intestinal tract is associated with increased incidence of postoperative complications after bowel surgery. High fluid volume administration may prevent occult regional hypoperfusion and intestinal tissue hypoxia. We tested the hypothesis that high intraoperative fluid volume administration increases intestinal wall tissue oxygen pressure during laparotomy.

METHODS

In all, 27 pigs were anaesthetized, ventilated and randomly assigned to one of the three treatment groups (n = 9 in each) receiving low (3 mL kg-1 h-1), medium (7 mL kg-1 h-1) or high (20 mL kg-1 h-1) fluid volume treatment with lactated Ringer's solution. All animals received 30% and 100% inspired oxygen in random order. Cardiac index was measured with thermodilution and tissue oxygen pressure with a micro-oximetry system in the jejunum and colon wall and subcutaneous tissue.

RESULTS

Groups receiving low and medium fluid volume treatment had similar systemic haemodynamics. The high fluid volume group had significantly higher mean arterial pressure, cardiac index and subcutaneous tissue oxygenation. Tissue oxygen pressures in the jejunum and colon were comparable in all three groups.

CONCLUSIONS

The three different fluid volume regimens tested did not affect tissue oxygen pressure in the jejunum and colon, suggesting efficient autoregulation of intestinal blood flow in healthy subjects undergoing uncomplicated abdominal surgery.

[Effect of prophylactic device "Braslet" on hemodynamic changes during long-term missions to orbital station Mir]

The benefit from occlusive cuffs (prophylactic device Braslet) to human hemodynamics was evaluated in seven cosmonauts on long-term Mir missions using the ultrasonic technique (Echography and Doppler). Braslet had a positive effect on cosmonauts" state of health during the first month of flight. Improvement of cerebral hemodynamics was attested objectively by reduction of venous congestion. However, the device did not produce a noticeable effect on the leg vein expansibility and capacity at the beginning of long-term mission. Starting on flight month 3, cumulation of the Braslet effect on the leg large veins resulted in progressive vein expansion. Regular wearing of the Braslet device produced changes in expansibility, capacity and elasticity of the veins in lower extremities. Extent of these changes was dependent on period of Braslet application and tightness of occlusion. Though the state of leg veins of the cosmonauts who had been favourable to Braslet during mission did not appear changed after landing, still we cannot make the conclusion that the occlusive cuffs do not bring harm if worn continuously, as their delayed effects have not been evaluated and remain unknown.

Determinanten des insensiblen Flüssigkeitsverlustes

Accurate perioperative fluid balance is the basis of a targeted infusion regimen. However, neither the initial status nor perioperative changes of the fluid compartments can be reliably measured in daily routine. In particular, insensible losses are not consistently assessed, so that substitution therapy is generally empirical. The object of this paper is to communicate the scientific data on this topic. Preoperative fasting (10 h) does not per se cause intravascular hypovolemia. In adults, total basal evaporation by way of the skin and airways and of any wounds during major abdominal interventions is usually less than 1 ml/kg/h. An inconstant fluid and protein shift towards the interstitial space perioperatively seems to be associated with hypervolemia, which suggests it should be preventable. The decisive factor in this context seems to be deterioration of the endothelial glycocalyx, whose further patho-physiological impact is currently only partially known. Clinical studies have revealed a link between fluid restriction and improved outcome after major abdominal surgery.

A Randomized Controlled Trial of Hydrocortisone Against Hyponatremia in Patients With Aneurysmal Subarachnoid Hemorrhage

BACKGROUND AND PURPOSE

Hyponatremia is common after aneurysmal subarachnoid hemorrhage (SAH). It is caused by natriuresis, which induces osmotic diuresis and decreases blood volume, contributing to symptomatic cerebral vasospasm (SCV). Hypervolemic therapy to prevent SCV will not be efficient under this condition. We conducted a randomized controlled trial to assess the efficacy of hydrocortisone, which promotes sodium retention in the kidneys.

METHODS

Seventy-one SAH patients were randomly assigned after surgery to treatment with either a placebo (n=36) or 1200 mg/d of hydrocortisone (n=35) for 10 days and tapered thereafter. Both groups underwent hypervolemic therapy. The primary end point was the prevention of hyponatremia.

RESULTS

Hydrocortisone prevented excess sodium excretion (P=0.04) and urine volume (P=0.04). Hydrocortisone maintained the targeted serum sodium level throughout the 14 days (P<0.001), and achieved the management protocol with lower sodium and fluid (P=0.007) supplementation. Hydrocortisone kept the normal plasma osmolarity (P<0.001). SCV occurred in 9 patients (25%) in the placebo group and in 5 (14%) in the hydrocortisone group. No significant difference in the overall outcome was observed between the 2 groups.

CONCLUSIONS

Hydrocortisone overcame excess natriuresis and prevented hyponatremia. Although there was no difference in outcome, hydrocortisone supported efficient hypervolemic therapy.

Perioperative fluid management: current consensus and controversies

The scientific knowledge base that supports clinical decisions about perioperative fluid management continues to evolve. However, despite these advancements in the understanding of the physiology of fluid replacement, the definition of ''optimal'' perioperative fluid management remains a matter of clinical judgment. With an appreciation of the many factors, both sensible and insensible, that contribute to changes in blood and extracellular fluid volume during surgery, clinicians have tried to create reproducible and generally applicable formulas for replacement of fluid during surgery. These formulas have been challenged recently by the introduction of new tools for monitoring cardiopulmonary function, by the implementation of monitor-guided protocols for fluid management, and, more recently, by clinical data suggesting that fluid restriction may improve surgical outcomes in some clinical settings. The relative ease of pre-identified fluid replacement protocols is being slowly replaced by data-guided interventions that take into account a variety of factors. Clinicians are therefore required to tailor their fluid replacement strategies based on preoperative patient characteristics, the type of surgery and even the type of anesthetic that is utilized. Some of the benefits of this new approach range from relatively ''minor'' outcomes such as diminished nausea after surgery to preventing postoperative complications such as wound breakdown and cardiopulmonary failure.

Monitoring of peri-operative fluid administration by individualized goal-directed therapy

BACKGROUND

In order to avoid peri-operative hypovolaemia or fluid overload, goal-directed therapy with individual maximization of flow-related haemodynamic parameters has been introduced. The objectives of this review are to update research in the area, evaluate the effects on outcome and assess the use of strategies, parameters and monitors for goal-directed therapy.

METHODS

A MEDLINE search (1966 to 2 October 2006) was performed to identify studies in which a goal-directed therapeutic strategy was used to maximize flow-related haemodynamic parameters in surgical patients, as well as studies referenced from these papers. Furthermore, methods applied in these studies and other monitors with a potential for goal-directed therapy are described.

RESULTS

Nine studies were identified pertaining to fluid optimization during the intra- and post-operative period with goal-directed therapy. Seven studies (n = 725) found a reduced hospital stay. Post-operative nausea and vomiting (PONV) and ileus were reduced in three studies and complications were reduced in four studies. Of the monitors that may be applied for goal-directed therapy, only oesophageal Doppler has been tested adequately; however, several other options exist.

CONCLUSION

Goal-directed therapy with the maximization of flow-related haemodynamic variables reduces hospital stay, PONV and complications, and facilitates faster gastrointestinal functional recovery. So far, oesophageal Doppler is recommended, but other monitors are available and call for evaluation.

Influence of “Liberal”versus “Restrictive” Intraoperative Fluid Administration on Elimination of a Postoperative Fluid Load

Background

Previously, the authors found "liberal" fluid administration (approximately 3 l Ringer's lactate [RL]) to improve early rehabilitation after laparoscopic cholecystectomy, suggesting functional hypovolemia to be present in patients receiving "restrictive" fluid administration (approximately 1 l RL). Because volume kinetic analysis after a volume load may distinguish between hypovolemic versus normovolemic states, the authors applied volume kinetic analysis after laparoscopic cholecystectomy to explain the difference in outcome between 3 and 1 l RL.

Methods

In a prospective, nonrandomized trial, the authors studied 20 patients undergoing laparoscopic cholecystectomy. Ten patients received 15 ml/kg RL (group 1) and 10 patients received 40 ml/kg RL (group 2) intraoperatively. All other aspects of perioperative management were standardized. A 12.5-ml/kg RL volume load was infused preoperatively and 4 h postoperatively. The distribution and elimination of the fluid load was estimated using volume kinetic analysis.

Results

Patient baseline demographics and intraoperative data did not differ between groups, except for intraoperative RL, having a median of 1,118 ml (range, 900-1,400 ml) in group 1 compared with a median of 2,960 ml (range, 2,000-3,960 ml) in group 2 (P&lt;0.01). There were no significant preoperative versus postoperative differences in the size of the body fluid space expanded by infused fluid (V), whereas the clearance constant kr was higher postoperatively versus preoperatively (P=0.03). The preoperative versus postoperative changes in volume kinetics including V were not different between the two groups.

Conclusions

Elimination of an intravenous fluid load was increased after laparoscopic cholecystectomy per se but not influenced by the amount of intraoperative fluid administration.

Facts and fallacies concerning the prevention of contrast medium-induced nephropathy

OBJECTIVE

The aim of this article is to extract from recent medical literature and nephrologic practice the facts and fallacies concerning the possible prophylaxis of contrast medium-induced nephropathy.

DATA SOURCES, STUDY SELECTION, AND DATA EXTRACTION

A MEDLINE/PubMed search (1985 to January 2006) was conducted, including all relevant articles investigating the pathogenesis and prevention of contrast medium-induced nephropathy from a nephrologic critical point of view.

DATA SYNTHESIS

Considerable efforts have been made to develop pharmacologic therapy for the prevention of contrast medium-induced nephropathy, especially in patients at risk, such as elderly subjects and those with preexisting renal impairment, hypovolemia, or dehydration. There is general consensus that hydration protocols implemented before and after imaging with contrast medium may be effective in preventing contrast medium-induced nephropathy. However, definitive and convincing data related to amounts to be infused, infusion timing, and type of solutions (half-isotonic, isotonic saline solution, or bicarbonate) are lacking. Forced diuresis with furosemide or mannitol and use of dopamine, together with concomitant hydration, have been proved to be ineffective or even more risky in the event of inadequate maintenance of euvolemia. Various direct or indirect vasodilators have been investigated (atrial natriuretic peptide, calcium channel blockers, angiotensin-converting enzyme inhibitors, and endothelin receptor antagonists), yet results have been inconsistent and inconclusive. Recent large meta-analyses concerning the protective role of antioxidant action of N-acetylcysteine have led to the conclusion that the statistical significance of the results is borderline. Preventive hemodialysis has not proved to be useful; on the contrary, it might worsen the clinical conditions by inducing hypotension. Hemofiltration, despite some positive studies, is too complex and cannot be used extensively.

CONCLUSIONS

: It is believed that prevention is actually achieved by correcting hypovolemia, dehydration, or both. Normalization of body fluids is probably the true objective to be achieved by preventive measures in all patients, not only in those at risk. Because limited data have been collected in intensive care units, at present, no firm or specific recommendations can yet be provided for the critically ill.

Fluid management of patients undergoing abdominal surgery – more questions than answers *

The 'wet vs. dry' philosophy in patients undergoing abdominal surgery is a subject of substantial debate. It has been suggested that restricting fluid input would significantly reduce complications and improve outcome following abdominal surgery. Keeping the patients dry may be a two-edged sword because the resulting hypovolaemia may result in compromised organ perfusion and poor tissue oxygenation. A review of the literature from 1990 to 2004 revealed that only very few studies on this subject have been published. Unfortunately, most of the 'dry'-supporting studies used fixed amounts of volume instead of a fluid concept adapted to the patients' need ('goal-directed') and there is no generally accepted definition of 'restricted', 'dry' or 'overload'. Not only the amount but also the kind of administered fluid appears to be important. Current evidence indicates that using crystalloids exclusively may cause overloading of the interstitial compartment with considerable negative sequelae, whereas using colloids may improve microperfusion and tissue oxygenation. This review shows that the meagre literature on a restricted volume replacement strategy in abdominal surgery patients cannot clearly support the 'dry' approach. Further well-performed studies are necessary to elucidate the ideal amount and type of fluid replacement and determine how to guide fluid therapy.

Cardiovascular dialysis instability and convective therapies

Acute hypotension is a frequent hemodialysis complication. Intratreatment vascular instability is a multifactorial process in which procedure-related and patient-related factors may influence the decrease in plasma volume and induce an impairment of cardiovascular regulatory mechanisms. Identification of the most susceptible patients and of the various risk factors may contribute to significantly improve cardiovascular stability during dialysis. In some high-risk patients, monitoring and biofeedback of the various hemodynamic variables, together with an extensive use of convection, can prevent the appearance of symptomatic hypotension and help in averting its onset.

Intraoperative oesophageal Doppler guided fluid management shortens postoperative hospital stay after major bowel surgery

BACKGROUND

Occult hypovolaemia is a key factor in the aetiology of postoperative morbidity and may not be detected by routine heart rate and arterial pressure measurements. Intraoperative gut hypoperfusion during major surgery is associated with increased morbidity and postoperative hospital stay. We assessed whether using intraoperative oesophageal Doppler guided fluid management to minimize hypovolaemia would reduce postoperative hospital stay and the time before return of gut function after colorectal surgery.

METHODS

This single centre, blinded, prospective controlled trial randomized 128 consecutive consenting patients undergoing colorectal resection to oesophageal Doppler guided or central venous pressure (CVP)-based (conventional) intraoperative fluid management. The intervention group patients followed a dynamic oesophageal Doppler guided fluid protocol whereas control patients were managed using routine cardiovascular monitoring aiming for a CVP between 12 and 15 mm Hg.

RESULTS

The median postoperative stay in the Doppler guided fluid group was 10 vs 11.5 days in the control group P<0.05. The median time to resuming full diet in the Doppler guided fluid group was 6 vs 7 for controls P<0.001. Doppler patients achieved significantly higher cardiac output, stroke volume, and oxygen delivery. Twenty-nine (45.3%) control patients suffered gastrointestinal morbidity compared with nine (14.1%) in the Doppler guided fluid group P<0.001, overall morbidity was also significantly higher in the control group P=0.05.

CONCLUSIONS

Intraoperative oesophageal Doppler guided fluid management was associated with a 1.5-day median reduction in postoperative hospital stay. Patients recovered gut function significantly faster and suffered significantly less gastrointestinal and overall morbidity.

Troubleshooting non-infectious peritoneal dialysis issues

Peritoneal dialysis is commonly preformed by patients and their caregivers in the home, in nursing homes, and in both acute and rehabilitation hospitals. The success of the therapy requires that the nurse overseeing the care of the patient on peritoneal dialysis in the acute, sub-acute, and chronic settings has the skills and knowledge to identify specific non-infectious issues, choose an appropriate and effective intervention activity, document the findings and outcomes, and educate the patient to assist in the resolution of the non-infectious issues, and avoid future recurrence. This article reviews the most common non-infectious complications that occur in patients on peritoneal dialysis and discusses an organized clinical process to troubleshoot the issues and achieve the desired clinical outcomes.

Fludrocortisone does not prevent orthostatic hypotension in astronauts after spaceflight

BACKGROUND

During stand/tilt tests after spaceflight, 20% of astronauts experience orthostatic hypotension and presyncope. Spaceflight-induced hypovolemia is a contributing factor. Fludrocortisone, a synthetic mineralocorticoid, has been shown to increase plasma volume and orthostatic tolerance in Earth-bound patients. The efficacy of fludrocortisone as a treatment for postflight hypovolemia and orthostatic hypotension in astronauts has not been studied. Our purpose was to test the hypothesis that astronauts who ingest fludrocortisone prior to landing would have less loss of plasma volume and greater orthostatic tolerance than astronauts who do not ingest fludrocortisone.

METHODS

There were 25 male astronauts who were randomized into 2 groups: placebo (n = 18) and fludrocortisone (n = 7), and participated in stand tests 10 d before launch and 2-4 h after landing. Subjects took either 0.3 mg fludrocortisone or placebo orally 7 h prior to landing. Supine plasma and red cell volumes, supine and standing HR, arterial pressure, aortic outflow, and plasma norepinephrine and epinephrine were measured.

RESULTS

On landing day, 2 of 18 in the placebo group and 1 of 7 in the fludrocortisone group became presyncopal (chi2 = 0.015, p = 0.90). Plasma volumes were significantly decreased after flight in the placebo group, but not in the fludrocortisone group. During postflight stand tests, standing plasma norepinephrine was significantly less in the fludrocortisone group compared with the placebo group.

CONCLUSIONS

Treatment with a single dose of fludrocortisone results in protection of plasma volume but no protection of orthostatic tolerance. Fludrocortisone is not recommended as a countermeasure for spaceflight-induced orthostatic intolerance.

High efficacy and minor renal effects of indomethacin treatment during individualized fluid intake in premature infants with patent ductus arteriosus

AIM

To determine the efficacy and the renal side effects of indomethacin treatment for closure of a patent ductus arteriosus (PDA) in premature infants during an individualized fluid regime that avoids hypovolaemia and subsequent prostaglandin-dependent renal perfusion.

METHODS

Observational retrospective analysis of the efficacy of indomethacin in premature infants with PDA treated in a single institution from June 1992 to May 2000. The clinical course and renal effects were analysed in the subgroup of infants born from June 1995 to May 2000. The management of infants at risk and the treatment of infants with PDA followed a standardized protocol that included echocardiographic screening for PDA, indomethacin treatment before congestive failure develops (early symptomatic treatment) and an individualized fluid intake.

RESULTS

In total, 412 infants with a gestational age < or = 32 wk were identified. Fifty-six infants with a PDA (14%) were treated with indomethacin [mean birthweight 936 (95% confidence interval 866-1006) g; gestational age 27.3 (26.8-27.9) wk]. Indomethacin treatment was successful in 52 infants (93%). The clinical course and renal effects were analysed in 41 infants. Most infants received three indomethacin doses of 0.2 mg kg(-1) every 12 h. Urine output transiently decreased from 5.6 (4.6-6.4) to 4.6 (3.9-5.3) ml kg(-1) (h(-1). Serum creatinine temporarily increased from 0.90 (0.83-0.98) to 1.06 (0.87-1.24)mg dl(-1). Fluid intake was 158 (148-168) ml kg(-1) d(-1) before indomethacin and decreased to 142 (131-154) ml kg(-1) d(-1).

CONCLUSION

Indomethacin is very effective for closure of a PDA, even in very premature infants, and is not associated with clinically significant renal side effects.

[Means of reducing blood loss and volume of the used transfused media in operative treatment of burn lesions of the liver]

An experience with surgical treatment of 77 patients with focal lesions of the liver is described. The patients were divided into two groups. In the main group (42 patients) the treatment-and-prophylactic method was used including acute isovolemic and hypervolemic hemodilution, preliminary preparation of autoblood, isolation and ligation of the vascular-secretory elements, the application for local hemostasis with Takhokomb of "Tissucol", gelatinous sponge with gentamycin. In the group of comparison the compression of the hepatoduodenal ligament, isolation of the vascular-secretory elements by digitoclasia method, suturing the liver stump with polysorb were used in resection of the liver. The strategy used in the main group allowed to reduce the volume of blood loss, to lessen the number of doses of the transfused donor blood, to diminish the number of postoperative complications by 30.5%. The used complex is effective, simple and is not expensive.

Daily use of the physio dialysis system: long-term experience

BACKGROUND

Hypovolaemia has been implicated as a major causal factor of morbidity during haemodialysis (HD). In order to avoid the appearance of destabilising hypovolaemia a biofeedback control system for intra-HD blood volume (BV) change modelling has been developed (Hemocontrol, Hospal Italy). It is based on an adaptive controller incorporated into a HD machine (Integra, Hospal Italy). The Hemocontrol biofeedback system (HBS) monitors BV contraction during HD with an optical device; furthermore, HBS modulates BV contraction rates (by adjusting the ultrafiltration rate--UFR) and the refilling rate (by adjusting dialysate conductivity--DC) in order to obtain the desired pre-determined BV trajectories.

METHODS

Nineteen patients prone to hypotension (7 males, 12 females, mean age 64.5 +/- 3.0 SEM years, on maintenance HD for 80.5 +/- 13.2 months) volunteered for the prospective study which aimed to compare the efficacy and safety of bicarbonate HD treatmentequipped with HBS, as a whole (HBS),with the gold standard, bicarbonate treatment, equipped with a constant UFR and DC (BD). The study included one period of 6 months of BD always preceding a follow-up period of HBS treatment ranging from 14 to 30 months (mean 24.0 +/- 1.6).

RESULTS

The overall occurrence of symptomatic hypotension and muscle cramps was significantly less in HBS treatment. Self-evaluation of intra- and inter-HD symptoms (the worst score was o and the best one 10) did reveal a statistically significant difference, as far as post-HD fatigue is concerned (6.2 +/- 0.2 in HBS vs. 4.3 +/- 0.1 in BD treatment, p < 0.0001). No difference between the two treatments was observed when comparing pre- and post-HD lying blood pressure, heart rate, body weights and body weight changes.

CONCLUSIONS

HBS is an effective treatment. Hypovolaemia-associated morbidity occurs less in BD treatment than HBS. Furthermore, HBS is a safe treatment in the medium-term because these results are achieved without potentially harmful changes in blood pressure, body weight and serum sodium concentration.