Challenges in translating plasma proteomics from bench to bedside: update from the NHLBI Clinical Proteomics Programs

The emerging scientific field of proteomics encompasses the identification, characterization, and quantification of the protein content or proteome of whole cells, tissues, or body fluids. The potential for proteomic technologies to identify and quantify novel proteins in the plasma that can function as biomarkers of the presence or severity of clinical disease states holds great promise for clinical use. However, there are many challenges in translating plasma proteomics from bench to bedside, and relatively few plasma biomarkers have successfully transitioned from proteomic discovery to routine clinical use. Key barriers to this translation include the need for "orthogonal" biomarkers (i.e., uncorrelated with existing markers), the complexity of the proteome in biological samples, the presence of high abundance proteins such as albumin in biological samples that hinder detection of low abundance proteins, false positive associations that occur with analysis of high dimensional datasets, and the limited understanding of the effects of growth, development, and age on the normal plasma proteome. Strategies to overcome these challenges are discussed.

Multicenter validation of a computer-based clinical decision support tool for glucose control in adult and pediatric intensive care units

INTRODUCTION

Hyperglycemia during critical illness is common, and intravenous insulin therapy (IIT) to normalize blood glucose improves outcomes in selected populations. Methods differ widely in complexity, insulin dosing approaches, efficacy, and rates of hypoglycemia. We developed a simple bedside-computerized decision support protocol (eProtocol-insulin) that yields promising results in the development center. We examined the effectiveness and safety of this tool in six adult and five pediatric intensive care units (ICUs) in other centers.

METHODS

We required attending physicians of eligible patients to independently intend to use intravenous insulin to normalize blood glucose. We used eProtocol-insulin for glucose control for a duration determined by the clinical caregivers. Adults had an anticipated length of stay of 3 or more days. In pediatric ICUs, we also required support or intended support with mechanical ventilation for greater than 24 hours or with a vasoactive infusion. We recorded all instances in which eProtocol-insulin instructions were not accepted and all blood glucose values. An independent data safety and monitoring board monitored study results and subject safety. Bedside nurses were selected randomly to complete a paper survey describing their perceptions of quality of care and workload related to eProtocol-insulin use.

RESULTS

Clinicians accepted 93% of eProtocol-insulin instructions (11,773/12,645) in 100 adult and 48 pediatric subjects. Forty-eight percent of glucose values were in the target range. Both of these results met a priori-defined efficacy thresholds. Only 0.18% of glucose values were < or =40 mg/dl. This is lower than values reported in prior IIT studies. Although nurses reported eProtocol-insulin required as much work as managing a mechanical ventilator, most nurses felt eProtocol-insulin had a low impact on their ability to complete non-IIT nursing activities.

CONCLUSIONS

A multicenter validation demonstrated that eProtocol-insulin is a valid, exportable tool that can assist clinicians in achieving control of glucose in critically ill adults and children.

Efficacy and safety of a paired sedation and ventilator weaning protocol for mechanically ventilated patients in intensive care (Awakening and Breathing Controlled trial): a randomised controlled trial

BACKGROUND

Approaches to removal of sedation and mechanical ventilation for critically ill patients vary widely. Our aim was to assess a protocol that paired spontaneous awakening trials (SATs)-ie, daily interruption of sedatives-with spontaneous breathing trials (SBTs).

METHODS

In four tertiary-care hospitals, we randomly assigned 336 mechanically ventilated patients in intensive care to management with a daily SAT followed by an SBT (intervention group; n=168) or with sedation per usual care plus a daily SBT (control group; n=168). The primary endpoint was time breathing without assistance. Data were analysed by intention to treat. This study is registered with ClinicalTrials.gov, number NCT00097630.

FINDINGS

One patient in the intervention group did not begin their assigned treatment protocol because of withdrawal of consent and thus was excluded from analyses and lost to follow-up. Seven patients in the control group discontinued their assigned protocol, and two of these patients were lost to follow-up. Patients in the intervention group spent more days breathing without assistance during the 28-day study period than did those in the control group (14.7 days vs 11.6 days; mean difference 3.1 days, 95% CI 0.7 to 5.6; p=0.02) and were discharged from intensive care (median time in intensive care 9.1 days vs 12.9 days; p=0.01) and the hospital earlier (median time in the hospital 14.9 days vs 19.2 days; p=0.04). More patients in the intervention group self-extubated than in the control group (16 patients vs six patients; 6.0% difference, 95% CI 0.6% to 11.8%; p=0.03), but the number of patients who required reintubation after self-extubation was similar (five patients vs three patients; 1.2% difference, 95% CI -5.2% to 2.5%; p=0.47), as were total reintubation rates (13.8%vs 12.5%; 1.3% difference, 95% CI -8.6% to 6.1%; p=0.73). At any instant during the year after enrolment, patients in the intervention group were less likely to die than were patients in the control group (HR 0.68, 95% CI 0.50 to 0.92; p=0.01). For every seven patients treated with the intervention, one life was saved (number needed to treat was 7.4, 95% CI 4.2 to 35.5).

INTERPRETATION

Our results suggest that a wake up and breathe protocol that pairs daily spontaneous awakening trials (ie, interruption of sedatives) with daily spontaneous breathing trials results in better outcomes for mechanically ventilated patients in intensive care than current standard approaches and should become routine practice.

Effect of sedation with dexmedetomidine vs lorazepam on acute brain dysfunction in mechanically ventilated patients: the MENDS randomized controlled trial

CONTEXT

Lorazepam is currently recommended for sustained sedation of mechanically ventilated intensive care unit (ICU) patients, but this and other benzodiazepine drugs may contribute to acute brain dysfunction, ie, delirium and coma, associated with prolonged hospital stays, costs, and increased mortality. Dexmedetomidine induces sedation via different central nervous system receptors than the benzodiazepine drugs and may lower the risk of acute brain dysfunction.

OBJECTIVE

To determine whether dexmedetomidine reduces the duration of delirium and coma in mechanically ventilated ICU patients while providing adequate sedation as compared with lorazepam.

DESIGN, SETTING, PATIENTS, AND INTERVENTION

Double-blind, randomized controlled trial of 106 adult mechanically ventilated medical and surgical ICU patients at 2 tertiary care centers between August 2004 and April 2006. Patients were sedated with dexmedetomidine or lorazepam for as many as 120 hours. Study drugs were titrated to achieve the desired level of sedation, measured using the Richmond Agitation-Sedation Scale (RASS). Patients were monitored twice daily for delirium using the Confusion Assessment Method for the ICU (CAM-ICU).

MAIN OUTCOME MEASURES

Days alive without delirium or coma and percentage of days spent within 1 RASS point of the sedation goal.

RESULTS

Sedation with dexmedetomidine resulted in more days alive without delirium or coma (median days, 7.0 vs 3.0; P = .01) and a lower prevalence of coma (63% vs 92%; P < .001) than sedation with lorazepam. Patients sedated with dexmedetomidine spent more time within 1 RASS point of their sedation goal compared with patients sedated with lorazepam (median percentage of days, 80% vs 67%; P = .04). The 28-day mortality in the dexmedetomidine group was 17% vs 27% in the lorazepam group (P = .18) and cost of care was similar between groups. More patients in the dexmedetomidine group (42% vs 31%; P = .61) were able to complete post-ICU neuropsychological testing, with similar scores in the tests evaluating global cognitive, motor speed, and attention functions. The 12-month time to death was 363 days in the dexmedetomidine group vs 188 days in the lorazepam group (P = .48).

CONCLUSION

In mechanically ventilated ICU patients managed with individualized targeted sedation, use of a dexmedetomidine infusion resulted in more days alive without delirium or coma and more time at the targeted level of sedation than with a lorazepam infusion.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00095251.

Attitudes and perceptions of patients towards methods of establishing a DNA biobank

BACKGROUND

This study aimed to assess patient attitudes as part of the planning process for a large-scale effort to collect genetic samples for research from excess clinical blood specimens ('DNA Databank' project).

METHOD

A pre-tested, 38-item questionnaire was mailed to a random sample of 5,000 inpatients, outpatients, and emergency department patients.

RESULTS

Approximately 20% of patients responded (n = 1003). Most were comfortable with anonymized genetic information being used for research (89.3%) and supported the potential benefits (98.7%). A binary logistic regression on the level of comfort with the DNA program shows that the variability in respondents' feelings about the program can best be explained by beliefs, age, and health status. Respondents were attitudinally segmented into 5 distinct categories.

CONCLUSIONS

These data indicate general acceptance among respondents, but a subset of the population would be opposed to the program. This reinforces the need to broadly and continuously communicate with patients about the program and the ability to exclude a given sample. The effects of prior beliefs would benefit from further exploration.

Comparison of the SpO2/FIO2 ratio and the PaO2/FIO2 ratio in patients with acute lung injury or ARDS

BACKGROUND

The diagnostic criteria for acute lung injury (ALI) and ARDS utilize the Pao(2)/fraction of inspired oxygen (Fio(2)) [P/F] ratio measured by arterial blood gas analysis to assess the degree of hypoxemia. We hypothesized that the pulse oximetric saturation (Spo(2))/Fio(2) (S/F) ratio can be substituted for the P/F ratio in assessing the oxygenation criterion of ALI.

METHODS

Corresponding measurements of Spo(2) (values </= 97%) and Pao(2) from patients enrolled in the ARDS Network trial of a lower tidal volume ventilator strategy (n = 672) were compared to determine the relationship between S/F and P/F. S/F threshold values correlating with P/F ratios of 200 (ARDS) and 300 (ALI) were determined. Similar measurements from patients enrolled in the ARDS Network trial of lower vs higher positive end-expiratory pressure (n = 402) were utilized for validation.

RESULTS

In the derivation data set (2,613 measurements), the relationship between S/F and P/F was described by the following equation: S/F = 64 + 0.84 x (P/F) [p < 0.0001; r = 0.89). An S/F ratio of 235 corresponded with a P/F ratio of 200, while an S/F ratio of 315 corresponded with a P/F ratio of 300. The validation database (2,031 measurements) produced a similar linear relationship. The S/F ratio threshold values of 235 and 315 resulted in 85% sensitivity with 85% specificity and 91% sensitivity with 56% specificity, respectively, for P/F ratios of 200 and 300.

CONCLUSION

S/F ratios correlate with P/F ratios. S/F ratios of 235 and 315 correlate with P/F ratios of 200 and 300, respectively, for diagnosing and following up patients with ALI and ARDS.

Acute lung injury and the acute respiratory distress syndrome: a clinical review

Acute respiratory distress syndrome and acute lung injury are well defined and readily recognised clinical disorders caused by many clinical insults to the lung or because of predispositions to lung injury. That this process is common in intensive care is well established. The mainstay of treatment for this disorder is provision of excellent supportive care since these patients are critically ill and frequently have coexisting conditions including sepsis and multiple organ failure. Refinements in ventilator and fluid management supported by data from prospective randomised trials have increased the methods available to effectively manage this disorder.

Mechanical ventilation in ARDS: a state-of-the-art review

Mechanical ventilation is an essential component of the care of patients with ARDS, and a large number of randomized controlled clinical trials have now been conducted evaluating the efficacy and safety of various methods of mechanical ventilation for the treatment of ARDS. Low tidal volume ventilation (</= 6 mL/kg predicted body weight) should be utilized in all patients with ARDS as it is the only method of mechanical ventilation that, to date, has been shown to improve survival. High positive end-expiratory pressure, alveolar recruitment maneuvers, and prone positioning may each be useful as rescue therapy in a patient with severe hypoxemia, but these methods of ventilation do not improve survival for the wide population of patients with ARDS. Although not specific to the treatment of ARDS, protocol-driven weaning that utilizes a daily spontaneous breathing trial and ventilation in the semirecumbent position have proven benefits and should be used in the management of ARDS patients.

Evaluation of the effectiveness of posters to provide information to patients about a DNA database and their opportunity to opt out

OBJECTIVE

Vanderbilt University Medical Center is implementing a DNA Databank to facilitate genomic research. This study describes the use of informational posters to communicate to patients about the Databank and their option to not participate.

METHODS

Informational posters were displayed in two phlebotomy areas prior to the implementation of the DNA Databank project. Patients leaving the phlebotomy areas were interviewed by non-medical personnel about the posters and the Databank using a structured interview guide.

RESULTS

Completed interviews with patients (n = 192) show that only 32% recalled seeing the posters (memory of the image only, or of the image and the content of the text). The majority of participants (93%) either recalled the poster or reported that they were comfortable with the DNA Databank concept after they had been read a brief statement about the program. A significant relationship (p = 0.001) appeared between respondents' awareness of research practices concerning anonymous discarded tissues and their level of comfort with the DNA Databank.

CONCLUSIONS

Individuals who report feeling uncomfortable with the Databank are an important population to inform about the Databank and opting out. Since there were no statistically significant demographic differences between those who recalled the poster and those who did not, there is no way to prospectively identify which patients will not be reached by the posters or who may feel uncomfortable with the program. Additional mechanisms to promote widespread notification are needed.

Acute lung injury and the acute respiratory distress syndrome: challenges in clinical trial design

Despite significant advances in the understanding of the complex pathophysiology, only a limited number of new treatments for acute lung injury (ALI) have emerged in the last 2 decades. This article discusses some of the challenges that remain in conducting clinical research in patients who have ALI and acute respiratory distress syndrome. New definitions that incorporate prognostic measures and reduce patient heterogeneity will allow more efficient enrollment of patients. Delineating outcomes attributable to the lung injury will improve the power of studies to detect significant treatment effects. Future collaborative studies will be needed to investigate longer-term clinical outcomes.

Risk factors for post-traumatic stress disorder symptoms following critical illness requiring mechanical ventilation: a prospective cohort study

INTRODUCTION

Post-traumatic stress disorder (PTSD) has been identified in a significant portion of intensive care unit (ICU) survivors. We sought to identify factors associated with PTSD symptoms in patients following critical illness requiring mechanical ventilation.

METHODS

Forty-three patients who were mechanically ventilated in the medical and coronary ICUs of a university-based medical center were prospectively followed during their ICU admission for delirium with the Confusion Assessment Method for the ICU. Additionally, demographic data were obtained and severity of illness was measured with the APACHE II (Acute Physiology and Chronic Health Evaluation II) score. Six months after discharge, patients were screened for PTSD symptoms by means of the Post-Traumatic Stress Syndrome 10-Questions Inventory (PTSS-10). Multiple linear regression was used to assess the association of potential risk factors with PTSS-10 scores.

RESULTS

At follow-up, six (14%) patients had high levels of PTSD symptoms. On multivariable analysis, women had higher PTSS-10 scores than men by a margin of 7.36 points (95% confidence interval [CI] 1.62 to 13.11; p = 0.02). Also, high levels of PTSD symptoms were less likely to occur in older patients, with symptoms declining after age 50 (p = 0.04). Finally, although causation cannot be assumed, the total dose of lorazepam received during the ICU stay was associated with PTSD symptoms; for every 10-mg increase in cumulative lorazepam dose, PTSS-10 score increased by 0.39 (95% CI 0.17 to 0.61; p = 0.04). No significant relationship was noted between severity of illness and PTSD symptoms or duration of delirium and PTSD symptoms.

CONCLUSION

High levels of PTSD symptoms occurred in 14% of patients six months following critical illness necessitating mechanical ventilation, and these symptoms were most likely to occur in female patients and those receiving high doses of lorazepam. High levels of PTSD symptoms were less likely to occur in older patients.

The role of the coagulation cascade in the continuum of sepsis and acute lung injury and acute respiratory distress syndrome

Sepsis is a common and life-threatening condition with a high mortality rate. Severe sepsis includes multiorgan dysfunction syndrome. The organ most often affected is the lung, with development of acute lung injury (ALI), which, in its most severe form, is referred to as acute respiratory distress syndrome (ARDS). Our understanding of inflammation in the pathogenesis of sepsis and ALI is continually growing. However, therapies aimed at the inflammatory cascade in sepsis have been unsuccessful. These failures have led investigators to consider other pathways that may be important in the development of sepsis and ALI, including the coagulation and fibrinolytic cascades. In fact, the first therapy to reduce mortality in sepsis modulates the coagulation cascade. With this clinical success, administration of drotecogin alfa (recombinant activated protein C), the importance of coagulation in the pathogenesis of human sepsis is becoming clearer. This review summarizes the current understanding of the role of coagulation and fibrinolytic abnormalities in sepsis and the development of ALI and ARDS. Both in vitro and in vivo studies of the role of the coagulation cascade in sepsis and lung injury will be discussed, including initiation of coagulation through modulation of tissue factor and tissue factor pathway inhibitor, propagation of coagulation via protein C and thrombomodulin, inhibition of thrombin generation and resolution through thrombolysis by plasminogen activator, and plasminogen activator inhibitor-1.

Safety and efficacy of affinity-purified, anti-tumor necrosis factor-alpha, ovine fab for injection (CytoFab) in severe sepsis

OBJECTIVE

Tumor necrosis factor (TNF) is a critical inflammatory mediator in sepsis. This trial was designed to evaluate the safety and effectiveness of polyclonal ovine anti-TNF fragment antigen binding (Fab) fragments (CytoFab) on plasma TNF-alpha, interleukin-6 (IL-6), and interleukin-8 (IL-8) concentrations and the number of shock-free and ventilator-free days in severely septic patients.

DESIGN

Phase II, randomized, blinded, placebo-controlled trial conducted from September 1997 to July 1998.

SETTING

Nineteen intensive care units in the United States and Canada.

PATIENTS

Eighty-one septic patients with either shock or two organ dysfunctions.

INTERVENTIONS

Patients were randomized to receive CytoFab, infused as a 250-units/kg loading dose, followed by nine doses of 50 units/kg every 12 hrs, or 5 mg/kg human albumin as placebo.

MEASUREMENTS AND MAIN RESULTS

CytoFab promptly reduced plasma TNF-alpha (p = .001) and IL-6 concentrations (p = .002) compared with placebo. CytoFab also significantly decreased TNF-alpha in bronchoalveolar lavage (BAL) fluid (p < .001). The number of shock-free days did not differ between CytoFab and placebo (10.7 vs. 9.4, respectively) (p = .270). CytoFab increased mean ventilator-free days (15.0 vs. 9.8 for placebo; p = .040) and ICU-free days (12.6 vs. 7.6 for placebo; p = .030) at day 28. All-cause, 28-day mortality rates were 37% (14/38) for placebo recipients, compared with 26% (11/43) for CytoFab recipients (p = .274). No differences in incidences of adverse events, laboratory, or vital sign abnormalities were observed between groups. Although 41% of CytoFab-treated patients developed detectable plasma levels of human anti-sheep antibodies, none demonstrated clinical manifestations during the 28-day study.

CONCLUSIONS

CytoFab is well tolerated in patients with severe sepsis, effectively reducing serum and BAL TNF-alpha and serum IL-6 concentrations and increasing the number of ventilator-free and ICU-free days at day 28.

A Case Series of Drotrecogin Alfa (Activated) in Lung Transplant Recipients

Severe sepsis in lung transplant recipients is a challenging problem and carries a high mortality. Recombinant human activated protein C (drotrecogin alfa [activated]) has been approved for use in patients with severe sepsis. Its use has been shown to be safe and impart a survival advantage. However, the safety of drotrecogin alfa activated has not been evaluated in lung transplant recipients. We report for the first time on the use of drotrecogin alfa activated in six lung transplant recipients. Clinical trials are warranted to further evaluate the use of drotrecogin alfa activated in transplant recipients.

Protein C concentrations in severe sepsis: an early directional change in plasma levels predicts outcome

INTRODUCTION

Protein C, because of its central role in hemostasis, plays an integral role in the host response to infection. Protein C depletion, resulting from increased consumption, degradation, and/or decreased synthesis, is characteristic of sepsis and has been shown to predict morbidity and mortality. The objective of this study was to determine whether early directional changes in protein C levels correlate with outcome.

METHODS

Patients in the Recombinant Human Activated Protein C Worldwide Evaluation in Severe Sepsis (PROWESS) clinical trial were assessed and categorized by baseline protein C (n = 1574). Deficiency was categorized as: severe deficiency, protein C levels < or = 40% of normal protein C activity (n = 615, 39% of patients); deficient, protein C levels 41-80% of normal protein C activity (n = 764, 48.5% of patients); and normal, >80% of normal protein C activity (n = 195, 12.4% of patients). Logistic regression analysis of 28-day mortality for placebo patients was used to investigate whether baseline and day 1 protein C levels were independent risk factors for mortality. The impact of treatment with drotrecogin alfa (activated) (DrotAA) was also assessed.

RESULTS

Protein C levels at baseline and day 1 were independent risk factors in placebo patients. If baseline protein C levels of severely deficient placebo patients remained < or = 40% at day 1 their odds of death increased (odds ratio = 2.75, P < 0.0001), while if levels improved to >40% by day 1 their risk of death decreased (odds ratio = 0.43, P = 0.03). If baseline protein C levels of placebo patients were >40% but decreased by > or = 10% on day 1, their risk of death increased (odds ratio = 1.87, P = 0.02). DrotAA treatment improved protein C levels by day 1 compared with placebo (P = 0.008) and reduced the risk of death in severely deficient (< or = 40%) patients at baseline. Treatment also decreased the number of severely protein C deficient (= 40%) patients and decreased the number of deficient (41-80%) patients and normal (>80%) patients who had a > or = 10% decrease in protein C levels by day 1.

CONCLUSION

Baseline protein C levels were an independent predictor of sepsis outcome. Day 1 changes in protein C, regardless of baseline levels, were also predictive of outcome. The association of DrotAA treatment, increased protein C levels, and improved survival may partially explain the mechanism of action.

Comparison of two fluid-management strategies in acute lung injury

BACKGROUND

Optimal fluid management in patients with acute lung injury is unknown. Diuresis or fluid restriction may improve lung function but could jeopardize extrapulmonary-organ perfusion.

METHODS

In a randomized study, we compared a conservative and a liberal strategy of fluid management using explicit protocols applied for seven days in 1000 patients with acute lung injury. The primary end point was death at 60 days. Secondary end points included the number of ventilator-free days and organ-failure-free days and measures of lung physiology.

RESULTS

The rate of death at 60 days was 25.5 percent in the conservative-strategy group and 28.4 percent in the liberal-strategy group (P=0.30; 95 percent confidence interval for the difference, -2.6 to 8.4 percent). The mean (+/-SE) cumulative fluid balance during the first seven days was -136+/-491 ml in the conservative-strategy group and 6992+/-502 ml in the liberal-strategy group (P<0.001). As compared with the liberal strategy, the conservative strategy improved the oxygenation index ([mean airway pressure x the ratio of the fraction of inspired oxygen to the partial pressure of arterial oxygen]x100) and the lung injury score and increased the number of ventilator-free days (14.6+/-0.5 vs. 12.1+/-0.5, P<0.001) and days not spent in the intensive care unit (13.4+/-0.4 vs. 11.2+/-0.4, P<0.001) during the first 28 days but did not increase the incidence or prevalence of shock during the study or the use of dialysis during the first 60 days (10 percent vs. 14 percent, P=0.06).

CONCLUSIONS

Although there was no significant difference in the primary outcome of 60-day mortality, the conservative strategy of fluid management improved lung function and shortened the duration of mechanical ventilation and intensive care without increasing nonpulmonary-organ failures. These results support the use of a conservative strategy of fluid management in patients with acute lung injury. (ClinicalTrials.gov number, NCT00281268 [ClinicalTrials.gov].).

Pulmonary-artery versus central venous catheter to guide treatment of acute lung injury

BACKGROUND

The balance between the benefits and the risks of pulmonary-artery catheters (PACs) has not been established.

METHODS

We evaluated the relationship of benefits and risks of PACs in 1000 patients with established acute lung injury in a randomized trial comparing hemodynamic management guided by a PAC with hemodynamic management guided by a central venous catheter (CVC) using an explicit management protocol. Mortality during the first 60 days before discharge home was the primary outcome.

RESULTS

The groups had similar baseline characteristics. The rates of death during the first 60 days before discharge home were similar in the PAC and CVC groups (27.4 percent and 26.3 percent, respectively; P=0.69; absolute difference, 1.1 percent; 95 percent confidence interval, -4.4 to 6.6 percent), as were the mean (+/-SE) numbers of both ventilator-free days (13.2+/-0.5 and 13.5+/-0.5; P=0.58) and days not spent in the intensive care unit (12.0+/-0.4 and 12.5+/-0.5; P=0.40) to day 28. PAC-guided therapy did not improve these measures for patients in shock at the time of enrollment. There were no significant differences between groups in lung or kidney function, rates of hypotension, ventilator settings, or use of dialysis or vasopressors. Approximately 90 percent of protocol instructions were followed in both groups, with a 1 percent rate of crossover from CVC- to PAC-guided therapy. Fluid balance was similar in the two groups, as was the proportion of instructions given for fluid and diuretics. Dobutamine use was uncommon. The PAC group had approximately twice as many catheter-related complications (predominantly arrhythmias).

CONCLUSIONS

PAC-guided therapy did not improve survival or organ function but was associated with more complications than CVC-guided therapy. These results, when considered with those of previous studies, suggest that the PAC should not be routinely used for the management of acute lung injury. (ClinicalTrials.gov number, NCT00281268.).

Lorazepam is an independent risk factor for transitioning to delirium in intensive care unit patients

BACKGROUND

Delirium has recently been shown as a predictor of death, increased cost, and longer duration of stay in ventilated patients. Sedative and analgesic medications relieve anxiety and pain but may contribute to patients' transitioning into delirium.

METHODS

In this cohort study, the authors designed a priori an investigation to determine whether sedative and analgesic medications independently increased the probability of daily transition to delirium. Markov regression modeling (adjusting for 11 covariates) was used in the evaluation of 198 mechanically ventilated patients to determine the probability of daily transition to delirium as a function of sedative and analgesic dose administration during the previous 24 h.

RESULTS

Lorazepam was an independent risk factor for daily transition to delirium (odds ratio, 1.2 [95% confidence interval, 1.1-1.4]; P = 0.003), whereas fentanyl, morphine, and propofol were associated with higher but not statistically significant odds ratios. Increasing age and Acute Physiology and Chronic Health Evaluation II scores were also independent predictors of transitioning to delirium (multivariable P values < 0.05).

CONCLUSIONS

Lorazepam administration is an important and potentially modifiable risk factor for transitioning into delirium even after adjusting for relevant covariates.

Drotrecogin alfa (activated) treatment in severe sepsis from the global open-label trial ENHANCE: further evidence for survival and safety and implications for early treatment

OBJECTIVE

To provide further evidence for the efficacy and safety of drotrecogin alfa (activated) treatment in severe sepsis.

DESIGN

Single-arm, open-label, trial of drotrecogin alfa (activated) treatment in severe sepsis patients. Enrollment began in March 2001 and day-28 follow-up completed in January 2003.

SETTING

ENHANCE took place in 25 countries at 361 sites.

PATIENTS

Patients with known or suspected infection, three or four systemic inflammatory response syndrome criteria, and one or more sepsis-induced organ dysfunctions. Of 2,434 adults entered, 2,378 received drotrecogin alfa (activated), and of these, 2,375 completed the protocol.

INTERVENTIONS

Drotrecogin alfa (activated) was infused at a dose of 24 mug/kg/hr for 96 hrs.

MEASUREMENTS AND MAIN RESULTS

The 28-day all-cause mortality approximated that observed in PROWESS (25.3% vs. 24.7%). Although patients in ENHANCE had increased serious bleeding rates compared with patients in the drotrecogin alfa (activated) arm of PROWESS (during infusion, 3.6% vs. 2.4%; postinfusion, 3.2% vs. 1.2%; 28-day, 6.5% vs. 3.5%), increased postinfusion bleeding suggested a higher background bleeding rate. Intracranial hemorrhage was more common in ENHANCE than PROWESS (during infusion, 0.6% vs. 0.2%; 28-day, 1.5% vs. 0.2%). The incidence of fatal intracranial hemorrhage was the same during infusion (0.2%) and higher at 28 days (0.5% vs. 0.2%). ENHANCE patients treated within 0-24 hrs from their first sepsis-induced organ dysfunction had lower observed mortality rate than those treated after 24 hrs (22.9% vs. 27.4%, p = .01).

CONCLUSIONS

ENHANCE provides supportive evidence for the favorable benefit/risk ratio observed in PROWESS and suggests that more effective use of drotrecogin alfa (activated) might be obtained by initiating therapy earlier.

Acute respiratory distress syndrome: innovative therapies

Since its description in 1967, the acute respiratory distress syndrome (ARDS) has become one of the most studied pathophysiological processes in intensive care units worldwide. The current state of knowledge about this severe illness and its associated mediators has come from the study of relevant animal models. In the mid-1970s, the development of the sheep model of ARDS and later, the porcine model, led to the discovery of a wide variety of inflammatory lipid mediators, cytokines, and proteases, to name but a few. Recognition of the presence of such highly toxic mediators associated with the development of ARDS has led to numerous potential targets for drug development toward therapeutic intervention. Through implementation of a standardized definition for ARDS and its less severe sibling acute lung injury (ALI), growth in patient-oriented research has been possible. Substantial numbers of new therapies have been brought forth and examined in recent years, many of which remain controversial. This article is a critical appraisal of the potential therapeutic options investigated in recent years for the management of ALI/ARDS.

Acute respiratory distress syndrome: a historical perspective

Though well described even in ancient writings, the acute respiratory distress syndrome (ARDS) gained major medical attention with the availability of mechanical ventilation and establishment of intensive care units. In the 50 years since this beginning there have been remarkable advances in the understanding of the etiology, physiology, histology, and epidemiology of this often lethal complication of common human maladies. Until recently, improvements in outcome have mainly followed improvements in intensive care unit operation and their associated life support systems, and have not come through discoveries made in the course of prospective randomized trials. In spite of the remarkable increase in research focused on ARDS, there remain a large number of unanswered clinical questions that are potentially extremely important with regard to short-term morbidity as well as long-term outcome. The ARDS Clinical Trials Network study of tidal volume has proven that randomized trials in ARDS with positive results are possible even when using difficult primary outcome measures such as mortality or ventilator-free days. Therefore, the rich combination of new trial strategies, potential treatments, experienced investigators, and increasingly standardized routine care set the stage for rapid advances to be made in the short- and long-term outcomes of this devastating syndrome.

A randomized, controlled trial of furosemide with or without albumin in hypoproteinemic patients with acute lung injury

OBJECTIVE

Hypoproteinemia is a common condition in critically ill patients, associated with the development of acute lung injury and acute respiratory distress syndrome and subsequent worse clinical outcomes. Albumin with furosemide benefits lung physiology in hypoproteinemic patients with acute lung injury/acute respiratory distress syndrome, but the independent pharmacologic effects of these drugs are unknown.

DESIGN

Randomized, double-blinded, placebo-controlled multicentered trial.

SETTING

Eleven medical, surgical, and trauma intensive care units including 190 beds within two university hospital systems.

PATIENTS

Forty mechanically ventilated patients with acute lung injury/acute respiratory distress syndrome, whose serum total protein concentrations were <6.0 g/dL were included. Patients were excluded for hemodynamic instability or significant renal or hepatic failure.

INTERVENTIONS

Subjects were equally randomly allocated to receive furosemide with albumin or furosemide with placebo for 72 hrs, titrated to fluid loss and normalization of serum total protein concentration.

MEASUREMENTS AND MAIN RESULTS

The primary outcome was change in oxygenation from baseline to day 1, with secondary physiologic and clinical outcomes. There were no differences in baseline characteristics of the subjects in relation to group assignment. Albumin-treated patients had greater increases in oxygenation (mean change in Pao2/Fio2: +43 vs. -24 mm Hg at 24 hrs and +49 vs. -13 mm Hg at day 3), serum total protein (1.5 vs. 0.5 g/dL at day 3), and net fluid loss (-5480 vs. -1490 mL at day 3) throughout the study period (all p < .05). Fluid bolus administration to control patients reduced net negative fluid balance; control patients more frequently developed hypotension and had fewer shock-free days, which translated to differences in organ failure at study end.

CONCLUSIONS

The addition of albumin to furosemide therapy in hypoproteinemic patients with acute lung injury/acute respiratory distress syndrome significantly improves oxygenation, with greater net negative fluid balance and better maintenance of hemodynamic stability. Additional randomized clinical trials are necessary to examine mechanisms and determine the effect on important clinical outcomes, such as the duration of mechanical ventilation.