Endpoints of resuscitation of critically injured patients: normal or supranormal? A prospective randomized trial

Haemodynamic goal-directed therapy and postoperative infections: earlier is better. A systematic review and meta-analysis

Introduction

Infectious complications are the main causes of postoperative morbidity. The early timing of their promoting factors is the rationale for perioperative strategies attempting to reduce them. Our aim was to determine the effects of perioperative haemodynamic goal-directed therapy on postoperative infection rates.

Methods

We performed a systematic review and meta-analysis. MEDLINE, EMBASE, The Cochrane Library and the DARE databases were searched up to March 2011. Randomised, controlled trials of major surgery in adult patients managed with perioperative goal-directed therapy or according to routine haemodynamic practice were included. Primary outcome measure was specific type of infection.

Results

Twenty-six randomised, controlled trials with a combined total of 4,188 participants met our inclusion criteria. Perioperative goal-directed therapy significantly reduced surgical site infections (pooled OR 0.58, 95% CI 0.46 to 0.74; P < 0.0001), pneumonia (pooled OR 0.71, 95% CI 0.55 to 0.92; P = 0.009), and urinary tract infections (pooled OR 0.44, 95% CI 0.22 to 0.84; P = 0.02). A significant benefit was found regarding total infectious episodes (OR 0.40, 95% CI 0.28 to 0.58; P < 0.00001).

Conclusions

Flow-directed haemodynamic therapy designed to optimise oxygen delivery protects surgical patients against postoperative hospital-acquired infections and must be strongly encouraged, particularly in the high-risk surgical population.

Does the Pulmonary Artery Catheter Still Have a Role in the Perioperative Period?

The pulmonary artery catheter (PAC) was introduced into clinical practice in the early 1970s. Its use quickly expanded beyond patients with acute myocardial infarction to critically ill patients in the intensive care unit. Increasingly, it was used in the perioperative period in patients having major cardiac and noncardiac surgery. Publication of large observational studies suggested that patients with a PAC were more likely to suffer major morbidity or mortality, but this was difficult to assess because patients who had a PAC inserted were often sicker, with more severe pathology, and were therefore more likely to die. The PAC is a monitoring device and information alone is unlikely to influence outcome unless it is linked to a proven therapy. Several thousand articles on the use of the PAC now exist, but in general, the quality of this literature is poor. Much of the data are not randomised, have small sample sizes and include patients with greatly differing pathological states. It is unclear which, if any, of the PAC-guided therapies are actually beneficial for patients. Despite these flaws, there is no clear evidence of benefit, nor harm, in cardiac, intensive care or perioperative patients. Selected indications for the PAC may remain, such as complex cardiac surgery or solid organ transplantation. However, its routine use is difficult to justify and increasingly, most of the haemodynamic data available from the PAC can be obtained less invasively with echocardiography.

The acute management of trauma hemorrhage: a systematic review of randomized controlled trials

Introduction

Worldwide, trauma is a leading cause of death and disability. Haemorrhage is responsible for up to 40% of trauma deaths. Recent strategies to improve mortality rates have focused on optimal methods of early hemorrhage control and correction of coagulopathy. We undertook a systematic review of randomized controlled trials (RCT) which evaluated trauma patients with hemorrhagic shock within the first 24 hours of injury and appraised how the interventions affected three outcomes: bleeding and/or transfusion requirements; correction of trauma induced coagulopathy and mortality.

Methods

Comprehensive searches were performed of MEDLINE, EMBASE, CENTRAL (The Cochrane Library Issue 7, 2010), Current Controlled Trials, ClinicalTrials.gov, the World Health Organization International Clinical Trials Registry Platform (ICTRP) and the National Health Service Blood and Transplant Systematic Review Initiative (NHSBT SRI) RCT Handsearch Database.

Results

A total of 35 RCTs were identified which evaluated a wide range of clinical interventions in trauma hemorrhage. Many of the included studies were of low methodological quality and participant numbers were small. Bleeding outcomes were reported in 32 studies; 7 reported significantly reduced transfusion use following a variety of clinical interventions, but this was not accompanied by improved survival. Minimal information was found on traumatic coagulopathy across the identified RCTs. Overall survival was improved in only three RCTs: two small studies and a large study evaluating the use of tranexamic acid.

Conclusions

Despite 35 RCTs there has been little improvement in outcomes over the last few decades. No clear correlation has been demonstrated between transfusion requirements and mortality. The global trauma community should consider a coordinated and strategic approach to conduct well designed studies with pragmatic endpoints.

Current concepts in resuscitation

Early recognition and differentiation of shock, as well as goal-directed resuscitation, are fundamental principles in the care of the critically ill or injured patient. Substantial progress has been made over the last decade in the understanding of both shock and resuscitation. Specific areas of advancement, particularly pertaining to hemorrhagic shock, include a heightened appreciation of dynamic measurements of preload responsiveness (e.g., respiratory-induced pulse pressure and venous diameter variability), an improved awareness of the detrimental effects of blood product transfusion, and better recognition of the complications of overzealous volume expansion. However, several areas of controversy remain regarding the optimal resuscitation strategy. These include the optimal targets for perfusion pressure and oxygen delivery, endpoints of resuscitation, resuscitative fluid, and transfusion strategies for packed red blood cells and blood products. This article reviews the diagnosis and differentiation of shock, measurements of tissue perfusion, current evidence regarding various resuscitative techniques, and complications of resuscitation.

Hemodynamic and perfusion end points for volemic resuscitation in sepsis

Sepsis is the systemic inflammatory response syndrome secondary to a local infection, and severe sepsis and septic shock are the more devastating scenarios of this disease. In the last decade, considerable achievements were obtained in sepsis knowledge, and an international campaign was developed to improve the treatment of this condition. However, sepsis is still one of the most important causes of death in intensive care units. The early stages of sepsis are characterized by a variety of hemodynamic derangements that induce a systemic imbalance between tissue oxygen supply and demand, leading to global tissue hypoxia. This dysfunction, which may occur in patients presenting normal vital signs, can be accompanied by a significant increase in both morbidity and mortality. The early identification of high-risk sepsis patients through tissue perfusion markers such as lactate and venous oxygen saturation is crucial for prompt initiation of therapeutic support, which includes early goal-directed therapy as necessary. The purpose of this article was to review the most commonly used hemodynamic and perfusion parameters for hemodynamic optimization in sepsis, emphasizing the physiological background for their use and the studies that demonstrated their effectiveness as goals of volemic resuscitation.

Maintaining tissue perfusion in high-risk surgical patients: a systematic review of randomized clinical trials

BACKGROUND

Surgical patients with limited organic reserve are considered high-risk patients and have an increased perioperative mortality. For this reason, they need a more rigorous perioperative protocol of hemodynamic control to prevent tissue hypoperfusion. In this study, we systematically reviewed the randomized controlled clinical trials that used a hemodynamic protocol to maintain adequate tissue perfusion in the high-risk surgical patient.

METHODS

We searched MEDLINE, Embase, LILACS, and Cochrane databases to identify randomized controlled clinical studies of surgical patients studied using a perioperative hemodynamic protocol of tissue perfusion aiming to reduce mortality and morbidity; the latter characterized at least one dysfunctional organ in the postoperative period. Pooled odds ratio (POR) and 95% confidence interval (CI) were calculated for categorical outcomes.

RESULTS

Thirty-two clinical trials were selected, comprising 5056 high-risk surgical patients. Global meta-analysis showed a significant reduction in mortality rate (POR: 0.67; 95% CI: 0.55-0.82; P < 0.001) and in postoperative organ dysfunction incidence (POR: 0.62; 95% CI: 0.55-0.70; P < 0.00,001) when a hemodynamic protocol was used to maintain tissue perfusion. When the mortality rate was >20% in the control group, the use of a hemodynamic protocol to maintain tissue optimization resulted in a further reduction in mortality (POR: 0.32; 95% CI: 0.21-0.47; P < 0.00,001). Monitoring cardiac output with a pulmonary artery catheter and increasing oxygen transport and/or decreasing consumption also significantly reduced mortality (POR: 0.67; 95% CI: 0.54-0.84; P < 0.001 and POR: 0.71; 95% CI: 0.57-0.88; P < 0.05, respectively). Therapy directed at increasing mixed or central venous oxygen saturation did not significantly reduce mortality (POR: 0.68; 95% CI: 0.22-2.10; P > 0.05). The only study using lactate as a marker of tissue perfusion failed to demonstrate a statistically significant reduction in mortality (OR: 0.33; 95% CI: 0.07-1.65; P > 0.05).

CONCLUSIONS

In high-risk surgical patients, the use of a hemodynamic protocol to maintain tissue perfusion decreased mortality and postoperative organ failure. Monitoring cardiac output calculating oxygen transport and consumption helped to guide therapy. Additional randomized controlled clinical studies are necessary to analyze the value of monitoring mixed or central venous oxygen saturation and lactate in high-risk surgical patients.

Using oxygen delivery targets to optimize resuscitation in critically ill patients

PURPOSE OF REVIEW

The use of fluid and inotropic therapies to optimize global haemodynamic variables, in particular oxygen delivery, in critically ill patients has been a controversial area of research for more than 25 years. The aim of this review is to describe the current evidence base for this treatment and how concepts of haemodynamic optimization have evolved in recent years.

RECENT FINDINGS

The inconsistent findings of a large number of small phase II trials continue to stimulate the debate about the value of this treatment approach. However, important recent developments include the use of optimization only during periods of resuscitation, more cautious doses of fluid and/or inotropic therapy, confirmation that pulmonary artery catheter use does not result in excess mortality and an improved understanding of the mechanistic effects of haemodynamic optimization.

SUMMARY

These advances in our understanding have now informed the design of large randomized trials in various patient groups. The true value of haemodynamic optimization is likely to be confirmed or refuted within the next 5 years.

Central venous pressure versus pulmonary artery catheter-directed shock resuscitation

Previously, we developed a protocol for shock resuscitation of severe trauma patients to reverse shock and regain hemodynamic stability during the first 24 intensive care unit (ICU) hours. Key hemodynamic measurements of cardiac output and preload were obtained using a pulmonary artery catheter (PAC). As an alternative, we developed a protocol that used central venous pressure (CVP) to guide decision making for interventions to regain hemodynamic stability [mean arterial pressure (MAP) >or= 65 mmHg and heart rate (HR) <or= 130 bpm]. Either protocol was available and required for traumatic shock resuscitation using bedside computerized clinical decision support to standardize decision making, and PAC was available if CVP-directed resuscitation was inadequate. We hypothesized that patients would be appropriately assigned to either protocol by trauma surgeon assessment of hemodynamic stability upon ICU admission. High-risk patients admitted to a level-1 trauma center ICU underwent resuscitation. Criteria were 1) major torso trauma, 2) base deficit (BD) >or= 6 mEq/L or systolic blood pressure < 90 mmHg, 3) transfusion of >or= 1 unit packed red blood cells (PRBC), or >or= age 65 years with two of three criteria. Patients with brain injury were excluded. Data were recorded prospectively. In 24 months ending July 31, 2006, of 193 patients, 114 (59%) were assigned CVP- directed resuscitation, and 79 (41%) were assigned PAC-directed resuscitation. A subgroup of 11 (10%) initially assigned CVP was reassigned PAC-directed resuscitation (7 +/- 2 h after start) due to hemodynamic instability. Crystalloid fluid and PRBC resuscitation volumes for PAC (8 +/- 1 L lactated Ringer's [LR], 5 +/- 0.4 units PRBC) were > CVP (5 +/- 0.4 L LR, 3 +/- 0.3 units PRBC) and similar to CVP - PAC protocol subgroup patients (9 +/- 2 L LR, 5 +/- 1 units PRBC). Intensive care unit (ICU) stay and survival rate for PAC (18 +/- 2 days, 75%) were similar to CVP - PAC (17 +/- 4 days, 73%) and worse than CVP protocol subgroup patients (9 +/- 1 days, 98%). Traumatic shock resuscitation is feasible using CVP as a primary hemodynamic monitor as part of a protocol that includes explicit definition of hemodynamic instability and where PAC monitoring is readily available. Computerized decision support provides a technique to implement complex protocol care processes and analyze patient response.

Pitfalls in the evaluation and resuscitation of the trauma patient

The management of the trauma patient presents the practitioner with a host of challenges, and the pace, variety of venues, and multidisciplinary nature of the field combine to create a system complexity that is laden with potential pitfalls. This review summarizes some of the general principles of medical errors and examines some of the more common pitfalls encountered in the initial resuscitation and evaluation of the major trauma patient.

Goal-directed haemodynamic therapy and gastrointestinal complications in major surgery: a meta-analysis of randomized controlled trials

Postoperative gastrointestinal (GI) dysfunction is one of the most frequent complications in surgical patients. Most cases are associated with episodes of splanchnic hypoperfusion due to hypovolaemia or cardiac dysfunction. It has been suggested that perioperative haemodynamic goal-directed therapy (GDT) may reduce the incidence of these complications in cardiac surgery, and other surgery, but clear evidence is lacking. We have undertaken a meta-analysis of the effects of GDT on postoperative GI and liver complications. A systematic search, using MEDLINE, EMBASE, and The Cochrane Library databases, was performed. Sixteen randomized controlled trials (3410 participants) met the inclusion criteria. Data synthesis was obtained using odds ratio (OR) with 95% confidence interval (CI) by random-effects model. Statistical heterogeneity was assessed by Q and I2 statistics. GI complications were ranked as major (required radiological or surgical intervention or life-threatening condition) or minor (no or only pharmacological treatment required). Major GI complications were significantly reduced by GDT when compared with a control group (OR, 0.42; 95% CI, 0.27-0.65). Minor GI complications were also significantly decreased in the GDT group (OR, 0.29; 95% CI, 0.17-0.50). Treatment did not reduce hepatic injury rate (OR, 0.54; 95% CI, 0.19-1.55). Quality sensitive analyses confirmed the main overall results. In patients undergoing major surgery, GDT, by maintaining an adequate systemic oxygenation, can protect organs particularly at risk of perioperative hypoperfusion and is effective in reducing GI complications.

Transfusion of aged packed red blood cells results in decreased tissue oxygenation in critically injured trauma patients

BACKGROUND

Blood transfusion is a common event in the treatment of injured patients. The effect of red blood cell transfusion on tissue oxygenation is unclear. The transfusion of older blood has been shown to be detrimental in retrospective studies. This study aims to study the effect of the age of the blood transfused on the tissue oxygenation using near infrared spectroscopy.

METHODS

Thirty-two critically injured trauma patients for whom a blood transfusion had been ordered were recruited. Each patient had a transcutaneous probe placed on the thenar eminence. The probe was placed 1 hour before the transfusion and left in place until 4 hours after transfusion. Tissue oxygen saturation (Sto2) was recorded every 2 minutes. The Sto2 area under the curve (AUC) over time periods was calculated. A control group (n = 16), not transfused, was recruited. The transfusion group was divided into two groups by blood age. One group received blood less than 21 days old, (new blood, n = 15) and the other received blood 21 days old or greater (old blood, n = 17). The data were analyzed for significance with Kendall's W and Wilcoxon's signed rank test (p < 0.05).

RESULTS

Baseline characteristics such were not significantly different between groups. The baseline AUC did not differ between groups. The old blood group demonstrated a significant decline in Sto2 comparing its baseline period to its transfusion period (p < 0.05). There was no similar decline in the control group or the new blood group. The posttransfusion period AUC for the old blood group was also lower versus baseline (p = 0.06). There was a moderate correlation between increasing age of blood and decrease in oxygenation (r = 0.5).

CONCLUSIONS

There was a decrease in peripheral tissue oxygenation in patients receiving older red blood cells. There was no oxygenation decrease in patients receiving blood less than 21 days. This indicates that factors in stored blood may influence the peripheral vasculature and oxygen delivery.

Computerized clinical decision support for traumatic shock resuscitation

PURPOSE OF REVIEW

To review what we learned through implementation of computerized decision support for ICU resuscitation of major torso trauma patients who arrive in shock.

RECENT FINDINGS

Overall, these patients respond well to preload-directed goal-orientated ICU resuscitation; however, the subset of patients destined to develop abdominal compartment syndrome do not respond well. In fact, this strategy precipitates the full-blown syndrome that is a new iatrogenic variant of multiple organ failure. The clinical trajectory of abdominal compartment syndrome starts early after emergency department admission and its course is fairly well defined by the time patients reach the ICU. It occurs in patients who arrive with severe bleeding that is not readily controlled. These patients require a very different emergency department management strategy. Hemorrhage control is paramount. Alternative massive transfusion protocols should be used with an emphasis on hemostasis and avoidance of excessive isotonic crystalloids. Finally, near-infrared spectroscopy that measures tissue hemoglobin saturation in skeletal muscle (StO2) is good at identifying high-risk patients. A falling StO2 in the setting of ongoing resuscitation is a harbinger of death from early exsanguination and multiple organ failure.

SUMMARY

Fundamental changes are needed in the care of trauma patients who arrive in shock and require a massive transfusion.

[Assessment of perioperative fluid balance]

Careful assessment of the fluid balance is required in the perioperative period since appropriate fluid therapy is essential for successful patient's outcome. Haemodynamic monitoring allows understanding the physiology of the circulation and changes of fluid balance in the perioperative period. This is diagnostic aid and guide for fluid replacement therapy. Patient's volume status is frequently assessed by different haemodynamic variables that could be targeted as the endpoints for fluid therapy and resuscitation. Fluid balance is the crucial factor in the maintenance of haemodynamic stability, tissue oxygenation and organ function. When the haemodynamic monitoring is applied in a rigorous and consistent manner, it reduces mortality and length of stay as well as costs incurred. There are a number of tests which describe the effectiveness of the invasive haemodynamic monitoring procedures usage. Since the pulmonary artery catheter (PAC) had been introduced into clinical practice it was considered as a golden standard for cardiac output measurements, haemodynamic and fluid balance assessment. Nevertheless, in previous 10 years new minimally invasive and noninvasive simple techniques for haemodynamic monitoring and patient's hydroelectricity status evaluation have been developed. They can replace PAC under different clinical circumstances and some of these techniques

Bench-to-bedside review: latest results in hemorrhagic shock

Hemorrhagic shock is a leading cause of death in trauma patients worldwide. Bleeding control, maintenance of tissue oxygenation with fluid resuscitation, coagulation support, and maintenance of normothermia remain mainstays of therapy for patients with hemorrhagic shock. Although now widely practised as standard in the USA and Europe, shock resuscitation strategies involving blood replacement and fluid volume loading to regain tissue perfusion and oxygenation vary between trauma centers; the primary cause of this is the scarcity of published evidence and lack of randomized controlled clinical trials. Despite enormous efforts to improve outcomes after severe hemorrhage, novel strategies based on experimental data have not resulted in profound changes in treatment philosophy. Recent clinical and experimental studies indicated the important influences of sex and genetics on pathophysiological mechanisms after hemorrhage. Those findings might provide one explanation why several promising experimental approaches have failed in the clinical arena. In this respect, more clinically relevant animal models should be used to investigate pathophysiology and novel treatment approaches. This review points out new therapeutic strategies, namely immunomodulation, cardiovascular maintenance, small volume resuscitation, and so on, that have been introduced in clinics or are in the process of being transferred from bench to bedside. Control of hemorrhage in the earliest phases of care, recognition and monitoring of individual risk factors, and therapeutic modulation of the inflammatory immune response will probably constitute the next generation of therapy in hemorrhagic shock. Further randomized controlled multicenter clinical trials are needed that utilize standardized criteria for enrolling patients, but existing ethical requirements must be maintained.

Pulmonary artery catheters: state of the controversy

Since 1970, pulmonary artery catheters (PACs) have been used in clinical practice to monitor the hemodynamic status of critically ill and injured patients. This technology was introduced and commercialized without considerable testing to determine safety and efficacy. After years of common clinical use, investigators identified potential increases in mortality associated with PAC use. For the past decade, investigators have studied various patient populations to elucidate the safety and efficacy of the PAC. This article reviews the historical context of PAC use, findings from recent clinical trials intended to determine safety and efficacy, issues with reliability and validity of PAC use, and complications associated with PAC use. Data from recent clinical trials do not support routine use of PACs, and the authors suggest that PAC-guided therapy should be the focus of study in future trials.

Secondary abdominal compartment syndrome after severe extremity injury: are early, aggressive fluid resuscitation strategies to blame?

INTRODUCTION

Secondary abdominal compartment syndrome (ACS) is the development of ACS in the absence of abdominal injury. The development of secondary ACS has been viewed by some authors as an unavoidable sequela of the aggressive crystalloid resuscitation often employed in the treatment of severe shock. We hypothesized that poor resuscitation techniques, including early and excessive crystalloid administration, places patients with extremity injuries at risk for developing secondary ACS.

METHODS

The Trauma Registry of the American College of Surgeons database was queried for all patients with an extremity Abbreviated Injury Scale (AIS) score of 3 or greater and abdominal AIS score of 0 treated at our institution between January 1, 2001 and December 31, 2005. The study group included those patients who developed secondary ACS, whereas the comparison cohort included those who did not develop secondary ACS.

RESULTS

Forty-eight patients developed secondary ACS and were compared with 48 randomly selected patients who had an extremity AIS score of 3 or greater and an abdomen AIS score of 0. There were no differences between the groups with respect to age, sex, race, or individual AIS scores. However, the secondary ACS group had a slightly higher Injury Severity Score (25.6 vs. 21.4, p = 0.02), significantly higher operating room crystalloid administration (9.9 L vs. 2.7 L, p < 0.001), and more frequent use of a rapid infuser (12.5% vs. 0.0%, p = 0.01). Multiple logistic regression identified prehospital and emergency department crystalloid as predictors of secondary ACS.

CONCLUSIONS

Aggressive resuscitation techniques, often begun in the prehospital setting, appear to increase the likelihood of patients with severe extremity injuries developing secondary ACS. Early, large volume crystalloid administration was the greatest predictor of secondary ACS.

What type of monitoring has been shown to improve outcomes in acutely ill patients?

OBJECTIVE

Lack of evidence that some monitoring systems can improve outcomes has raised doubts about their use in the intensive care unit (ICU). The objective of this study was to determine which monitoring techniques have been shown to improve outcomes in ICU patients.

DESIGN

Comprehensive literature review.

METHODS

We conducted a highly sensitive search, up to June 2006, in the Cochrane Central Register of Controlled Trials (CENTRAL) and MedLine, for prospective, randomized controlled trials (RCTs) conducted in adult patients in the ICU and the operating room (major surgical procedures) and focusing on the impact of monitoring on outcome.

MEASUREMENTS AND RESULTS

Of 4,175 potential articles, 67 evaluated the impact of monitoring in acutely ill adult patients. There were 40 studies related to hemodynamic monitoring, 17 to respiratory monitoring, and 10 to neurological monitoring. Seven studies were classified in two different categories. Positive non-mortality outcomes were observed in 17 of 40 hemodynamic studies, 11 of 17 respiratory, and in all 10 neurological studies. Mortality was evaluated in 31 hemodynamic studies, but a beneficial impact was demonstrated in only 10. For respiratory monitoring, 7 studies evaluated mortality, but only 3 of them showed an improved outcome. We found no neurological monitoring studies that assessed mortality.

CONCLUSION

There is no broad evidence that any form of monitoring improves outcomes in the ICU and most commonly used devices have not been evaluated by RCT. This review puts into perspective the recent negative studies on the use of the pulmonary artery catheter in the acutely ill.

The phenomenon of "fluid creep" in acute burn resuscitation

Several reports have documented that modern burn patients receive far more resuscitation fluid than predicted by the Parkland formula-a phenomenon termed "fluid creep." This article reviews the incidence, consequences, and possible etiologies of fluid creep in modern practice and uses this information to propose some therapeutic strategies to reduce or eliminate excessive fluid resuscitation in burn care. A literature review was performed of historical references that form the foundation of modern fluid resuscitation, as well as reports of fluid creep and its consequences. The original Parkland formula required a 24-hour volume of 4 ml/kg/%TBSA lactated Ringer's solution followed by an infusion of 0.3-0.5 ml/kg/ %TBSA plasma. Modern iterations of this formula have omitted the colloid bolus. Numerous exceptions to the formula have been noted, most consistently patients with inhalation injuries. In contrast, recent reports document greatly increased fluid requirements in unselected patients, which seems to consist largely of progressive edema formation in unburned areas, increasing after the first 8 hours post-burn. This has been linked to occurrence of the abdominal compartment syndrome and other serious complications. Strategies to reduce fluid creep include the avoidance of early overresuscitation, use of colloid as a routine component of resuscitation or for "rescue," and adherence to protocols for fluid resuscitation. Fluid creep is a significant problem in modern burn care. Review of original investigations of burn shock, coupled with modern reports of fluid creep, suggests several mechanisms by which this problem can be controlled. Prospective trials of these therapies are needed to confirm their effectiveness.

Blood tranfusion in critically ill patients: state of the art

Anemia is one of the most common abnormal findings in critically ill patients, and many of these patients will receive a blood transfusion during their intensive care unit stay. However, the determinants of exactly which patients do receive transfusions remains to be defined and have been the subject of considerable debate in recent years. Concerns and doubts have emerged regarding the benefits and safety of blood transfusion, in part due to the lack of evidence of better outcomes resulting from randomized studies and in part related to the observations that transfusion may increase the risk of infection. As a result of these concerns and of several studies suggesting better or similar outcomes with a lower transfusion trigger, there has been a general tendency to decrease the transfusion threshold from the classic 10 g/dL to lower values. In this review, we focus on some of the key studies providing insight into current transfusion practices and fueling the current debate on the ideal transfusion trigger.

Evidence-based review of the use of the pulmonary artery catheter: impact data and complications

The pulmonary artery catheter (PAC) was introduced in 1971 for the assessment of heart function at the bedside. Since then it has generated much enthusiasm and controversy regarding the benefits and potential harms caused by this invasive form of hemodynamic monitoring. This review discusses all clinical studies conducted during the past 30 years, in intensive care unit settings or post mortem, on the impact of the PAC on outcomes and complications resulting from the procedure. Although most of the historical observational studies and randomized clinical trials also looked at PAC-related complications among their end-points, we opted to review the data under two main topics: the impact of PAC on clinical outcomes and cost-effectiveness, and the major complications related to the use of the PAC.

Resuscitation for major trauma

Disability from traumatic injury is on the increase worldwide. Dogma rather than scientific evidence has tended to be responsible for determining the treatment of major trauma victims. Evidence is now beginning to emerge, however, questioning the dogma, and suggesting that different treatment options may yield better outcomes. This review examines the recent literature in resuscitation for major trauma.

Fluid management of the trauma patient

Hemodynamic instability in the trauma patient is most commonly secondary to blood loss and the accumulation of fluid in injured tissue. The etiologies of shock unrelated to hypovolemia must also be investigated. The treatment of hypovolemia in patients with non-cerebral trauma should begin with Ringer's lactate solution. Normal saline (0.9% sodium chloride) is appropriate for patients with head injury, alkalosis, or hyponatremia, but in large volumes may lead to metabolic acidosis. The role of colloids, hypertonic saline, and hemoglobin solutions in trauma resuscitation is unclear at the present time. Base deficit and lactate levels are useful as predictors of morbidity and mortality and can be used to guide resuscitation.

Measurement of acid-base resuscitation endpoints: lactate, base deficit, bicarbonate or what?

PURPOSE OF REVIEW

Inadequate oxygen delivery to the tissues frequently results in significant metabolic acidosis. The resultant cellular and organ dysfunction can increase morbidity, mortality and hospital stay. Early diagnosis of shock can lead to early resuscitation efforts that can prevent ongoing tissue injury. This review focuses on the metabolic, hemodynamic and regional perfusion endpoints utilized in the diagnosis of metabolic acidosis resulting from shock. Resuscitation strategies aimed at supranormal oxygen delivery will be discussed.

RECENT FINDINGS

Serum pH, lactate, base deficit and bicarbonate have all been extensively studied as clinical markers of metabolic acidosis in shock. While their trend helps guide resuscitation, no single marker or specific value can be utilized to guide resuscitation for all patients. Hemodynamic parameters and regional tissue endpoints are designed to identify compensated shock before it progresses to uncompensated shock. Resuscitation strategies initiated in the early phases of shock can reduce complications and death. Efforts to resuscitate patients to supranormal oxygen delivery endpoints have demonstrated mixed success, with several notable complications.

SUMMARY

Despite the large number of endpoints available to the clinician, none are universally applicable and none have independently demonstrated improved survival when guiding resuscitation. Patients who respond well to initial resuscitation efforts demonstrate a survival advantage over nonresponders.

New developments in fluid resuscitation

Hemorrhagic shock is the leading cause of death in civilian and military trauma. Effective hemorrhage control and optimal resuscitation are the main goals in the management of severely injured patients. This article addresses the changing trends in fluid resuscitation in regards to who, when, and how. Much of these changing trends are caused by the recognition that the current method of resuscitation with crystalloid fluids may not be optimal and may even have detrimental consequences. This article summarizes a number of studies that have evaluated the cellular toxicities of commonly used resuscitation fluids, to highlight the need for the development of new fluids.

Practical issues of hemodynamic monitoring at the bedside

The hemodynamic monitoring of a surgical patient acquires a major relevance in high-risk patients and those suffering from surgical diseases associated with hemodynamic instability, such as hemorrhagic or septic shock. This article reviews the fundamental physiologic principles needed to understand hemodynamic monitoring at the bedside. Monitoring defines stability, instability, and response to therapy. The major hemodynamic parameters measured and derived from invasive hemodynamic monitoring, such as arterial, central venous, and pulmonary catheterization, are discussed, as are its clinical indications, benefits, and complications. The current clinical data relevant to hemodynamic monitoring are reviewed and discussed.

Effect of DHEA on the Hemodynamic Response to Resuscitation in a Porcine Model of Hemorrhagic Shock

BACKGROUND

Hemorrhagic shock is a major cause of death from trauma. Pharmacologic treatment has not been satisfactory. The objective of this study was to use a porcine model of hemorrhagic shock and resuscitation to access the hemodynamic effects of dehydroepiandrosterone (DHEA), an adrenal steroid hormone reported to improve cardiac function in patients.

METHODS

Hemorrhagic shock was produced in 20- to 30-kg male Yorkshire pigs anesthetized with 2% isoflurane by withdrawing blood through a carotid cannula to a mean arterial pressure (MAP) of 40 to 45 mm Hg and maintaining that level for 60 minutes by further removals of blood. Resuscitation was with 21 mL/kg Ringer's lactate (LR), with (n = 6) or without (n = 6) DHEA (4 mg/kg) dissolved in propylene glycol. The animals were killed after 7 days. Continuous cardiac output (CCO) was recorded using a modified Swan-Ganz catheter system. MAP, heart rate (HR), central venous pressure (CVP), and pulmonary arterial pressure (PAP) were measured every 5 minutes until 60 minutes postresuscitation. From MAP, CCO, HR, and CVP, we calculated total peripheral resistance (TPR), stroke volume (SV), and left ventricular stroke work (SW).

RESULTS

The MAP, CCO, SV, and SW decreased significantly during hemorrhagic shock, and then gradually increased to baseline levels during and 1 hour after resuscitation. The TPR was increased during hemorrhagic shock, and then gradually decreased to baseline levels during and after resuscitation. DHEA administration was associated with no significant improvement.

CONCLUSION

DHEA when added to standard fluid resuscitation showed no added benefit as resumed by the hemodynamic response.

An update on fluid resuscitation

Hemorrhagic shock is the leading cause of death in civilian and military trauma. Effective hemorrhage control and better resuscitation strategies have the potential of saving lives. However, if not performed properly, resuscitation can actually exacerbate cellular injury caused by hemorrhagic shock, and the type of fluid used for resuscitation plays an important role in this injury pattern. It is logical to prevent this cellular injury through wiser resuscitation strategies than attempting immunomodulation after the damage has already occurred. It is important to recognize that unlike numerous other variables, resuscitation is completely under our control. We decide who, when and how should get resuscitated. This paper summarizes data from a number of studies to illustrate the differential effects of commonly used resuscitation fluids on cellular injury, and how these relate to clinical practice. In addition, some novel resuscitation strategies are described that may become clinically available in the near future.

Conventional neurocritical care and cerebral oxygenation after traumatic brain injury

Object

Control of intracranial pressure (ICP) and cerebral perfusion pressure (CPP) is the foundation of traumatic brain injury (TBI) management. In this study, the authors examined whether conventional ICP- and CPP-guided neurocritical care ensures adequate brain tissue O2 in the first 6 hours after resuscitation.

Methods

Resuscitated patients with severe TBI (Glasgow Coma Scale score ≤ 8 and Injury Severity Scale score ≥ 16) who were admitted to a Level I trauma center and who underwent brain tissue O2 monitoring within 6 hours of injury were evaluated as part of a prospective observational database. Therapy was directed to maintain an ICP of 25 mm Hg or less and a CPP of 60 mm Hg or higher.

Data from a group of 25 patients that included 19 men and six women (mean age 39 ± 20 years) were examined. After resuscitation, ICP was 25 mm Hg or less in 84% and CPP was 60 mm Hg or greater in 88% of the patients. Brain O2 probes were allowed to stabilize; the initial brain tissue O2 level was 25 mm Hg or less in 68% of the patients, 20 mm Hg or less in 56%, and 10 mm Hg or less in 36%. Nearly one third (29%) of patients with ICP readings of 25 mm Hg or less and 27% with CPP levels of 60 mm Hg or greater had severe cerebral hypoxia (brain tissue O2 ≤10 mm Hg). Nineteen patients had both optimal ICP (≤25 mm Hg) and CPP (> 60 mm Hg); brain tissue O2 was 20 mm Hg or less in 47% and 10 mm Hg or less in 21% of these patients. The mortality rate was higher in patients with reduced brain tissue O2.

Conclusions

Brain resuscitation based on current neurocritical care standards (that is, control of ICP and CPP) does not prevent cerebral hypoxia in some patients. This finding may help explain why secondary neuronal injury occurs in some patients with adequate CPP and suggests that the definition of adequate brain resuscitation after TBI may need to be reconsidered.

TRAUMA RECEPTION AND RESUSCITATION

The hospital reception phase of major trauma management requires a great number of expedient decisions. However, despite widely taught programmes advocating a standardized, algorithmic approach to decision-making, there is an ongoing rate of human errors contributing to adverse outcomes. It is now time for a fundamental change in our approach to trauma resuscitation. Point-of-care computer technology linked to real-time decision-making and trauma team coordination may achieve error reduction through standardized decision-making and a corresponding reduction in preventable mortality and morbidity.

Pulmonary artery catheter use is associated with reduced mortality in severely injured patients: a National Trauma Data Bank analysis of 53,312 patients

OBJECTIVE

To evaluate the association between pulmonary artery catheter (PAC) use and mortality in a large cohort of injured patients. We hypothesized that PAC use is associated with improved survival in critically injured trauma patients.

DESIGN

Retrospective database analysis.

SETTING

A total of 268 level 1 trauma centers from across the United States.

PATIENTS

A total of 53,312 patients admitted to the intensive care units of the trauma centers participating in the National Trauma Data Bank maintained by the American College of Surgeons.

MEASUREMENTS AND MAIN RESULTS

The National Trauma Data Bank was queried to identify patients aged 16-90 yrs with complete data on base deficit, and Injury Severity Score (n=53,312). Patients were initially divided into two groups: those managed with a PAC (n=1,933) and those managed without a PAC (n=51,379). Chi-square and Student's t-test analysis were utilized to explore group differences in mortality. In a second analysis, groups were stratified by base deficit, Injury Severity Score, and age to further explore the influence of injury severity on PAC use and mortality. In addition, a logistic regression model was developed to assess the relationship between PAC use and mortality after adjusting for differences in age, mechanism, injury severity, injury pattern, and co-morbidities. Overall, patients managed with a PAC were older (45.8+/-21.3 yrs), had higher Injury Severity Score (28.4+/-13.5), worse base deficit (-5.2+/-6.5), and increased mortality (PAC, 29.7%; no PAC, 9.8%; p<.001). However, after stratification for injury severity, PAC use was associated with a survival benefit in four subgroups of patients. Each of these groups had advanced age or increased injury severity. Specifically, patients aged 61-90 yrs, with arrival base deficit worse than -11 and Injury Severity Score of 25-75, had a decrease in the risk of death with PAC use (odds ratio, 0.33; 95% confidence interval, 0.17-0.62). Three additional groups had a similar decrease in the risk of death with PAC use: odds ratio, 0.60 (95% confidence interval, 0.43-0.83), 0.82 (95% confidence interval, 0.44-1.52), and 0.63 (95% confidence interval, 0.40-0.98). Logistic regression analysis demonstrated a decreased mortality when a PAC was used in the management of patients with the following severe injury characteristics: Injury Severity Score of 25-75, base deficit of less than -11, or age of 61-90 yrs (odds ratio, 0.593; 95% confidence interval, 0.437-0.805).

CONCLUSIONS

Trauma patients managed with a PAC are more severely injured and have a higher mortality. However, severely injured patients (Injury Severity Score, 25-75) who arrive in severe shock, and older patients, have an associated survival benefit when managed with a PAC. This is the first study to demonstrate a benefit of PAC use in trauma patients.

Reduced Heart Rate Variability: An Indicator of Cardiac Uncoupling and Diminished Physiologic Reserve in 1,425 Trauma Patients

BACKGROUND

Measurements of a patient's physiologic reserve (age, injury severity, admission lactic acidosis, transfusion requirements, and coagulopathy) reflect robustness of response to surgical insult. We have previously shown that cardiac uncoupling (reduced heart rate variability, HRV) in the first 24 hours after injury correlates with mortality and autonomic nervous system failure. We hypothesized: Deteriorating physiologic reserve correlates with reduced HRV and cardiac uncoupling.

METHODS

There were 1,425 trauma ICU patients that satisfied the inclusion criteria. Differences in mortality across categorical measurements of the domains of physiologic reserve were assessed using the chi test. The relationship of cardiac uncoupling and physiologic reserve was examined using multivariate logistic regression models for various levels of cardiac uncoupling (>0 through 28% reduced HRV in the first 24 hours).

RESULTS

Of these, 797 (55.9%) patients exhibited cardiac uncoupling. Deteriorating measures of physiologic reserve reflected increased risk of death. Measures of acidosis (admission lactate, time to lactate normalization, and lactate deterioration over the first 24 hours), coagulopathy, age, and injury severity contributed significantly to the risk of cardiac uncoupling (area under receiver operator curve, ROC=0.73). The association between deteriorating reserve and cardiac uncoupling increases with the threshold for uncoupling (ROC=0.78).

CONCLUSIONS

Reduced heart rate variability is a new biomarker reflecting the loss of command and control of the heart (cardiac uncoupling). Risk of cardiac uncoupling increases significantly as a patient's physiologic reserve deteriorates and physiologic exhaustion approaches. Cardiac uncoupling provides a noninvasive, overall measure of a patient's clinical trajectory over the first 24 hours of ICU stay.

Continuous noninvasive monitoring of cardiac performance and tissue perfusion in pediatric trauma patients

PURPOSE

The aim of this study was to assess the accuracy of a continuous survival probability prediction using noninvasive measures of cardiac performance and tissue perfusion in severely injured pediatric patients.

METHODS

Review of all patients entered into a prospective noninvasive monitoring protocol. Cardiac index (CI) was measured using a thoracic bioimpedance device and tissue perfusion was assessed by transcutaneous carbon dioxide (Ptcco(2)) tension and oxygen tension indexed to the fraction of inspired oxygen (Ptco(2)/Fio(2)). Survival probability (SP) was continuously calculated using a stochastic analysis program.

RESULTS

There were 45 patients with a total of 953 data sets. The mean age was 11 years (range, 1-16 years) with a mean Injury Severity Score of 24 (+/-16). There was no difference between survivors (n = 32) and nonsurvivors (n = 13) at study entry for heart rate, blood pressure, CI, or pulse oximetry (all P > .05). However, survivors demonstrated higher Ptcco(2) (45 vs 35), higher Ptco(2)/Fio(2) (236 vs 156), and higher predicted SP (89% vs 62%) compared with nonsurvivors at study entry and throughout the monitoring period (all P < .01). For the entire data set, the strongest independent predictors of survival were Ptco(2)/Fio(2) and SP. The area under the receiver operating characteristic curve for mortality prediction was 0.83 for SP and 0.71 for Ptco(2)/Fio(2), compared with 0.6 for heart rate, 0.51 for blood pressure, and 0.53 for CI. Similar hemodynamic patterns were observed for all injury patterns with the exception of those with severe brain injury.

CONCLUSIONS

Thoracic bioimpedance and transcutaneous monitoring give critical real-time hemodynamic and tissue perfusion data that can provide early identification of pathologic flow patterns and accurately predict survival.

Meta-analysis of hemodynamic optimization: relationship to methodological quality

Introduction

To review systematically the effect of interventions aimed at hemodynamic optimization and to relate this to the quality of individual published trials.

Methods

A systematic, computerized bibliographic search of published studies and citation reviews of relevant studies was performed. All randomized clinical trials in which adult patients were included in a trial deliberately aiming at an optimized or maximized hemodynamic condition of the patients (with oxygen delivery, cardiac index, oxygen consumption, mixed venous oxygen saturation and/or stroke volume as end-points) were selected. A total of 30 studies were selected for independent review. Two reviewers extracted data on population, intervention, outcome and methodological quality. Agreement between reviewers was high: differences were eventually resolved by third-party decision. The methodological quality of the studies was moderate (mean 9.0, SD 1.7), and the outcomes of the randomized clinical trials were not related to their quality.

Results

Efforts to achieve an optimized hemodynamic condition resulted in a decreased mortality rate (relative risk ratio (RR) 0.75 (95% confidence interval (CI) 0.62 to 0.90) in all studies combined. This was due to a significantly decreased mortality in peri-operative intervention studies (RR 0.66 (95% CI 0.54 to 0.81). Overall, patients with sepsis and overt organ failure do not benefit from this method (RR 0.92 (95% CI 0.75 to 1.11)).

Conclusion

This systematic review showed that interventions aimed at hemodynamic optimization reduced mortality. In particular, trials including peri-operative interventions aimed at the hemodynamic optimization of high-risk surgical patients reduce mortality. Overall, this effect was not related to the trial quality.

Perioperative fluid management and clinical outcomes in adults

The administration of IV fluid to avoid dehydration, maintain an effective circulating volume, and prevent inadequate tissue perfusion should be considered, along with the maintenance of sleep, pain relief, and muscular relaxation, a core element of the perioperative practice of anesthesia. Knowledge of the effects of different fluids has increased in recent years, and the choice of fluid type in a variety of clinical situations can now be rationally guided by an understanding of the physicochemical and biological properties of the various crystalloid and colloid solutions available. However, there are few useful clinical outcome data to guide this decision. Deciding how much fluid to give has historically been more controversial than choosing which fluid to use. A number of clinical studies support the notion that an approach based on administering fluids to achieve maximal left ventricular stroke volume (while avoiding excess fluid administration and consequent impairment of left ventricular performance) may improve outcomes. In this article, we review the available fluid types and strategies of fluid administration and discuss their relationship to clinical outcomes in adults.

New strategies to improve outcomes in the surgical intensive care unit

BACKGROUND

Over the last half-decade, substantial breakthroughs have taken place in terms of routine therapy of critically ill patients. The combination of these strategies has the potential to result in improvement in the overall outcomes for patients in intensive care units.

METHODS

A focused review was undertaken of trials of interventions in critically ill patients with outcome endpoints.

RESULTS

This review discusses recent results related to transfusion avoidance, new drug therapy of sepsis, low tidal volume ventilation, tight glycemic control, early goal-directed resuscitation in sepsis, and the contribution of intensivists to improved outcomes.

CONCLUSIONS

Appropriate incorporation of these strategies into everyday practice will likely result in improvements in the care of critically ill surgical patients.

Splanchnic Hypoperfusion-Directed Therapies in Trauma: A Prospective, Randomized Trial

Splanchnic hypoperfusion as reflected by gastric intramucosal acidosis has been recognized as an important determinant of outcome in shock. A comprehensive splanchnic hypoperfusion-ischemia reperfusion (IRP) protocol was evaluated against conventional shock management protocols in critical trauma patients. The study was a prospective randomized trial comparing three therapeutic approaches to hypoperfusion after severe trauma in 151 trauma patients admitted to the intensive care unit. Group 1 patients received hemodynamic support based on conventional indicators of hypoperfusion. In group 2, resuscitation was further guided by gastric tonometry-derived estimates of splanchnic hypoperfusion and included more invasive hemodynamic monitoring and additional administration of colloid or crystalloid solutions, or inotropic support. Group 3 patients additionally received therapies specifically aimed at optimizing splanchnic perfusion and minimizing oxidant-mediated damage from reperfusion. The three groups were similar based on age, Injury Severity Score, and Acute Physiology and Chronic Health Evaluation II Scores. There were no statistically significant differences in mortality rates, organ dysfunction, ventilator days, or length of stay between any of the interventions. Techniques of optimization of splanchnic perfusion and minimization of oxidant-mediated reperfusion injury evaluated in this study were not advantageous relative to standard resuscitation measures guided by conventional or tonometric measures of hypoperfusion in the therapy of occult and clinical shock in trauma patients.