Relationship of mortality to increasing oxygen delivery in patients > or = 50 years of age: a prospective, randomized trial

Utilizing Near-Infrared Spectroscopy to Identify Pediatric Trauma Patients Needing Lifesaving Interventions: A Prospective Study

OBJECTIVES

The aim of this study was to prospectively investigate the role of near-infrared spectroscopy (NIRS) in identifying pediatric trauma patients who required lifesaving interventions (LSIs).

METHODS

Prospective cohort study of children age 0 to 18 years who activated the trauma team response between August 15, 2017, and February 12, 2019, at a large, urban pediatric emergency department (ED).The relationship between the lowest somatic NIRS saturation and the need for LSIs (based on published consensus definition) was investigated. Categorical variables were analyzed by χ 2 test, and continuous variables were analyzed by Student t test.

RESULTS

A total of 148 pediatric trauma patients had somatic NIRS monitoring and met the inclusion criteria. Overall, 65.5% were male with a mean ± SD age of 10.9 ± 6.0 years. Injuries included 67.6% blunt trauma and 28.4% penetrating trauma with mortality of 3.4% (n = 5). Overall, the median lowest somatic NIRS value was 72% (interquartile range, 58%-88%; range, 15%-95%), and 43.9% of patients had a somatic NIRS value <70%. The median somatic NIRS duration recorded was 11 minutes (interquartile range, 7-17 minutes; range, 1-105 minutes). Overall, 36.5% of patients required a LSI including 53 who required a lifesaving procedure, 17 required blood products, and 17 required vasopressors. Among procedures, requiring a thoracostomy was significant.Pediatric trauma patients with a somatic NIRS value <70% had a significantly increased odds of requiring a LSI (odds ratio, 2.11; 95% confidence interval, 1.07-4.20). Somatic NIRS values <70% had a sensitivity and specificity of 56% and 63%, respectively.

CONCLUSIONS

Pediatric trauma patients with somatic NIRS values <70% within 30 minutes of ED arrival have an increased odds of requiring LSIs. Among LSIs, pediatric trauma patients requiring thoracostomy was significant. The role of NIRS in incrementally improving the identification of critically injured children in the ED and prehospital setting should be evaluated in larger prospective multicenter studies.

Utilizing Near-Infrared Spectroscopy (NIRS) to Identify Pediatric Trauma Patients Needing Lifesaving Interventions (LSIs): A Retrospective Study

OBJECTIVES

The aim of this study was to investigate the role of near-infrared spectroscopy (NIRS) in identifying pediatric trauma patients who required lifesaving interventions (LSIs).

METHODS

Retrospective chart review of children age 0 to 18 years who activated the trauma team response between January 1, 2015 and August 14, 2017, at a large, urban pediatric emergency department. The lowest somatic NIRS saturation and the need for LSIs (based on published consensus definition) were abstracted from the chart. χ2 and descriptive statistics were used for analysis.

RESULTS

The charts of 84 pediatric trauma patients were reviewed. Overall, 80% were boys with a mean age of 10.4 years (SD, 6.2 years). Injuries included 56% blunt trauma and 36% penetrating trauma with mortality of 10.7% (n = 9). Overall, the median lowest NIRS value was 67% (interquartile range, 51-80%; range, 15%-95%) and 54.8% of the patients had a NIRS value less than 70%. The median somatic NIRS duration recorded was 12 minutes (interquartile range, 6-17 minutes; range, 1-59 minutes). Overall, 50% of patients required a LSI, including 39 who required a lifesaving procedure, 11 required blood products, and 14 required vasopressors. Pediatric trauma patients with NIRS less than 70% had a significantly increased odds of requiring a LSI (odds ratio, 2.67; 95% confidence interval, 1.10-6.47). NIRS less than 70% had a sensitivity and specificity of 67% and 57% respectively.

CONCLUSIONS

Pediatric trauma patients with somatic NIRS less than 70% within 30 minutes of emergency department arrival are associated with the need for LSIs. Continuous NIRS monitoring in the pediatric trauma population should be evaluated prospectively.

Impact of hemodynamic goal-directed resuscitation on mortality in adult critically ill patients: a systematic review and meta-analysis

The effect of hemodynamic optimization in critically ill patients has been challenged in recent years. The aim of the meta-analysis was to evaluate if a protocolized intervention based on the result of hemodynamic monitoring reduces mortality in critically ill patients. We performed a systematic review and meta-analysis according to the Cochrane Handbook for Systematic Reviews of Interventions. The study was registered in the PROSPERO database (CRD42015019539). Randomized controlled trials published in English, reporting studies on adult patients treated in an intensive care unit, emergency department or equivalent level of care were included. Interventions had to be protocolized and based on results from hemodynamic measurements, defined as cardiac output, stroke volume, stroke volume variation, oxygen delivery, and central venous-or mixed venous oxygenation. The control group had to be treated without any structured intervention based on the parameters mentioned above, however, monitoring by central venous pressure measurements was allowed. Out of 998 screened papers, thirteen met the inclusion criteria. A total of 3323 patients were enrolled in the six trials with low risk of bias (ROB). The mortality was 22.4% (374/1671 patients) in the intervention group and 22.9% (378/1652 patients) in the control group, OR 0.94 with a 95% CI of 0.73–1.22. We found no statistically significant reduction in mortality from hemodynamic optimization using hemodynamic monitoring in combination with a structured algorithm. The number of high quality trials evaluating the effect of protocolized hemodynamic management directed towards a meaningful treatment goal in critically ill patients in comparison to standard of care treatment is too low to prove or exclude a reduction in mortality.

The effect of early goal-directed therapy for treatment of severe sepsis or septic shock: A systemic review and meta-analysis

PURPOSE

To assess the effects of early goal-directed therapy (EGDT) on reducing mortality compared with conventional management of severe sepsis or septic shock.

MATERIALS AND METHODS

We included a systemic review, using the Medline and EMBASE. Seventeen randomized trials with 5765 patients comparing EGDT with usual care were included.

RESULTS

There were no significant differences in mortality between EGDT and control groups (relative risk [RR], 0.89; 95% confidence interval [CI], 0.79-1.00), with moderate heterogeneity (I2=56%). The EGDT was associated with lower mortality rates when the mortality rate of the usual care group was greater than 30% (12 trials; RR, 0.83; 95% CI, 0.72-0.96), but not when the mortality rate in the usual care group was less than 30% (5 trials; RR, 1.03; 95% CI, 0.92-1.16). The mortality benefit was seen only in subgroup of population analyzed between publication of the 2004 and 2012 Surviving Sepsis Campaign guidelines, but not before and after these publications.

CONCLUSION

This meta-analysis was heavily influenced by the recent addition of the trio of trials published after 2014. The results of the recent trio of trials may be biased due to methodological issues. This includes lack of blinding by incorporating similar diagnostic and therapeutic interventions as the original EGDT trial.

Near Infrared Spectroscopy as a Hemodynamic Monitor in Critical Illness

OBJECTIVES

The objectives of this review are to discuss the technology and clinical interpretation of near infrared spectroscopy oximetry and its clinical application in patients with congenital heart disease.

DATA SOURCE

MEDLINE and PubMed.

CONCLUSION

Near infrared spectroscopy provides a continuous noninvasive assessment of tissue oxygenation. Over 20 years ago, near infrared spectroscopy was introduced into clinical practice for monitoring cerebral oxygenation during cardiopulmonary bypass in adults. Since that time, the utilization of near infrared spectroscopy has extended into the realm of pediatric cardiac surgery and is increasingly being used in the cardiac ICU to monitor tissue oxygenation perioperatively.

The effect of goal-directed therapy on mortality in patients with sepsis - earlier is better: a meta-analysis of randomized controlled trials

INTRODUCTION

The Surviving Sepsis Campaign guidelines recommend goal-directed therapy (GDT) for the early resuscitation of patients with sepsis. However, the findings of the ProCESS (Protocolized Care for Early Septic Shock) trial showed no benefit from GDT for reducing mortality rates in early septic shock. We performed a meta-analysis to integrate these findings with existing literature on this topic and evaluate the effect of GDT on mortality due to sepsis.

METHODS

We searched the PubMed, Embase and CENTRAL (Cochrane Central Register of Controlled Trials) databases and reference lists of extracted articles. Randomized controlled trials comparing GDT with standard therapy or usual care in patients with sepsis were included. The prespecified primary outcome was overall mortality.

RESULTS

In total, 13 trials involving 2,525 adult patients were included. GDT significantly reduced overall mortality in the random-effects model (relative risk (RR), 0.83; 95% confidence interval (CI), 0.71 to 0.96; P =0.01; I 2 = 56%). Predefined subgroup analysis according to the timing of GDT for resuscitation suggested that a mortality benefit was seen only in the subgroup of early GDT within the first 6 hours (seven trials; RR, 0.77; 95% CI, 0.67 to 0.89; P =0.0004; I 2 = 40%), but not in the subgroup with late or unclear timing of GDT (six trials; RR, 0.92; 95% CI, 0.69 to 1.24; P =0.59; I 2 = 56%). GDT was significantly associated with the use of dobutamine (five trials; RR, 2.71; 95% CI, 1.20 to 6.10; P =0.02).

CONCLUSIONS

The results of the present meta-analysis suggest that GDT significantly reduces overall mortality in patients with sepsis, especially when initiated early. However, owing to the variable quality of the studies, strong and definitive recommendations cannot be made.

Individually optimized hemodynamic therapy reduces complications and length of stay in the intensive care unit: a prospective, randomized controlled trial

BACKGROUND

The authors hypothesized that goal-directed hemodynamic therapy, based on the combination of functional and volumetric hemodynamic parameters, improves outcome in patients with cardiac surgery. Therefore, a therapy guided by stroke volume variation, individually optimized global end-diastolic volume index, cardiac index, and mean arterial pressure was compared with an algorithm based on mean arterial pressure and central venous pressure.

METHODS

This prospective, controlled, parallel-arm, open-label trial randomized 100 coronary artery bypass grafting and/or aortic valve replacement patients to a study group (SG; n = 50) or a control group (CG; n = 50). In the SG, hemodynamic therapy was guided by stroke volume variation, optimized global end-diastolic volume index, mean arterial pressure, and cardiac index. Optimized global end-diastolic volume index was defined before and after weaning from cardiopulmonary bypass and at intensive care unit (ICU) admission. Mean arterial pressure and central venous pressure served as hemodynamic goals in the CG. Therapy was started immediately after induction of anesthesia and continued until ICU discharge criteria, serving as primary outcome parameter, were fulfilled.

RESULTS

Intraoperative need for norepinephrine was decreased in the SG with a mean (±SD) of 9.0 ± 7.6 versus 14.9 ± 11.1 µg/kg (P = 0.002). Postoperative complications (SG, 40 vs. CG, 63; P = 0.004), time to reach ICU discharge criteria (SG, 15 ± 6 h; CG, 24 ± 29 h; P < 0.001), and length of ICU stay (SG, 42 ± 19 h; CG, 62 ± 58 h; P = 0.018) were reduced in the SG.

CONCLUSION

Early goal-directed hemodynamic therapy based on cardiac index, stroke volume variation, and optimized global end-diastolic volume index reduces complications and length of ICU stay after cardiac surgery.

Perioperative increase in global blood flow to explicit defined goals and outcomes following surgery

BACKGROUND

Studies have suggested that increasing whole body blood flow and oxygen delivery around the time of surgery reduces mortality, morbidity and the expense of major operations.

OBJECTIVES

To describe the effects of increasing perioperative blood flow using fluids with or without inotropes or vasoactive drugs. Outcomes were mortality, morbidity, resource utilization and health status.

SEARCH METHODS

We searched CENTRAL (The Cochrane Library 2012, Issue 1), MEDLINE (1966 to March 2012) and EMBASE (1982 to March 2012). We manually searched the proceedings of major conferences and personal reference databases up to December 2011. We contacted experts in the field and pharmaceutical companies for published and unpublished data.

SELECTION CRITERIA

We included randomized controlled trials with or without blinding. We included studies involving adult patients (aged 16 years or older) undergoing surgery (patients having a procedure in an operating room). The intervention met the following criteria. 'Perioperative' was defined as starting up to 24 hours before surgery and stopping up to six hours after surgery. 'Targeted to increase global blood flow' was defined by explicit measured goals that were greater than in controls, specifically one or more of cardiac index, oxygen delivery, oxygen consumption, stroke volume (and the respective derived indices), mixed venous oxygen saturation (SVO(2)), oxygen extraction ratio (0(2)ER) or lactate.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted the data. We contacted study authors for additional data. We used Review Manager software.

MAIN RESULTS

We included 31 studies of 5292 participants. There was no difference in mortality: 282/2615 (10.8%) died in the control group and 238/2677 (8.9%) in the treatment group, RR of 0.89 (95% CI 0.76 to 1.05, P = 0.18). However, the results were sensitive to analytical methods and the intervention was better than control when inverse variance or Mantel-Haenszel random-effects models were used, RR of 0.72 (95% CI 0.55 to 0.95, P = 0.02). The results were also sensitive to withdrawal of studies with methodological limitations. The rates of three morbidities were reduced by increasing global blood flow: renal failure, RR of 0.71 (95% CI 0.57 to 0.90); respiratory failure, RR of 0.51 (95% CI 0.28 to 0.93); and wound infections, RR of 0.65 (95% CI 0.51 to 0.84). There were no differences in the rates of nine other morbidities: arrhythmia, pneumonia, sepsis, abdominal infection, urinary tract infection, myocardial infarction, congestive cardiac failure or pulmonary oedema, or venous thrombosis. The number of patients with complications was reduced by the intervention, RR of 0.68 (95% CI 0.58 to 0.80). Hospital length of stay was reduced in the treatment group by a mean of 1.16 days (95% CI 0.43 to 1.89, P = 0.002). There was no difference in critical care length of stay. There were insufficient data to comment on quality of life and cost effectiveness.

AUTHORS' CONCLUSIONS

It remains uncertain whether increasing blood flow using fluids, with or without inotropes or vasoactive drugs, reduces mortality in adults undergoing surgery. The primary analysis in this review (mortality at longest follow-up) showed no difference between the intervention and control, but this result was sensitive to the method of analysis, the withdrawal of studies with methodological limitations, and is dominated by a single large RCT. Overall, for every 100 patients in whom blood flow is increased perioperatively to defined goals, one can expect 13 in 100 patients (from 40/100 to 27/100) to avoid a complication, 2/100 to avoid renal impairment (from 8/100 to 6/100), 5/100 to avoid respiratory failure (from 10/100 to 5/100), and 4/100 to avoid postoperative wound infection (from 10/100 to 6/100). On average, patients receiving the intervention stay in hospital one day less. It is unlikely that the intervention causes harm. The balance of current evidence does not support widespread implementation of this approach to reduce mortality but does suggest that complications and duration of hospital stay are reduced.

A prospective randomized trial using blood volume analysis in addition to pulmonary artery catheter, compared with pulmonary artery catheter alone, to guide shock resuscitation in critically ill surgical patients

Measurement of blood volume (BV) may guide fluid and red blood cell management in critically ill patients when capillary leak from shock and fluid resuscitation makes assessment of intravascular volume difficult. This is a prospective randomized trial of critically ill surgical patients with septic shock, severe sepsis, severe respiratory failure, and/or cardiovascular collapse. The control group received fluid management based on pulmonary artery catheter parameters and red blood cell transfusions based on hematocrit values. The BV group received fluid and red blood cell transfusions based on BV analyses in addition to pulmonary artery catheter parameters. Blood volume was measured using the radioisotope tracer technique with iodine 131-labeled albumin. This allowed direct measurement of plasma volume and calculation of the red blood cell volume. The control group was blinded to the BV results. There were statistically significantly more times when the control group (compared with the BV group) demonstrated hypervolemia (48% vs. 37%) and red blood cell deficiency (33% vs. 16%). There was a delay in red blood cell transfusions administered to the control group by 1.5 +/- 2 days at which time the abnormality became clinically evident. Blood volume analyses provided additional information to the clinicians resulting in a change in treatment in 44% of the time to patients randomized to the BV group. The mortality rates were significantly different between the two groups (8% for the BV group and 24% in the control group; P = 0.03). Blood volume measurements allowed the physicians to promptly treat physiologic disturbances in both red blood cell volume and plasma volume, resulting in improved survival.

Near-infrared spectroscopy as a hemodynamic monitor in critical illness

BACKGROUND

Near-infrared spectroscopy has moved from a research tool to a widely used clinical monitor in the critically ill pediatric patient over the last decade. The physiological and clinical evidence supporting this technology in practice is reviewed here.

METHODOLOGY

A search of MEDLINE and PubMed was conducted to find validation studies, controlled trials, and other reports of near-infrared spectroscopy use in children and adults in the clinical setting. Guidelines published by the American Heart Association, the American Academy of Pediatrics, and the International Liaison Committee on Resuscitation were reviewed including further review of references cited.

RESULTS

The biophysical properties of near-infrared spectroscopy devices allow measurement of capillary-venous oxyhemoglobin saturation in tissues a few centimeters beneath the surface sensor with validated accuracy in neonates, infants, and small patients. The biologic basis for the relationship of capillary-venous oxyhemoglobin saturation to cerebral injury has been described in animal and human studies. Normal ranges for cerebral and somatic capillary-venous oxyhemoglobin saturation have been described for normal newborns and infants and children with congenital heart disease and other disease states. The capillary-venous oxyhemoglobin saturation from both cerebral and somatic regions has been used to estimate mixed venous saturation and to predict biochemical shock, multiorgan dysfunction, and mortality in different populations. The relationship of cerebral capillary-venous oxyhemoglobin saturation to neuroimaging and functional assessment of outcome is limited but ongoing. Although there are numerous conflicting reports in small populations, expert opinion would suggest that special use may exist for near-infrared spectroscopy in patients with complex circulatory anatomy, with extremes of physiology, and in whom extended noninvasive monitoring is useful.

CONCLUSIONS

Class II, level B evidence supports the conclusion that near-infrared spectroscopy offers a favorable risk-benefit profile and can be effective and beneficial as a hemodynamic monitor for the care of critically 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.

Blood lactate monitoring in critically ill patients: a systematic health technology assessment

OBJECTIVE

To decide whether the use of blood lactate monitoring in critical care practice is appropriate. We performed a systematic health technology assessment as blood lactate monitoring has been implemented widely but its clinical value in critically ill patients has never been evaluated properly.

DATA SOURCE

PubMed, other databases, and citation review.

STUDY SELECTION

We searched for lactate combined with critically ill patients as the target patient population. Two reviewers independently selected studies based on relevance for the following questions: Does lactate measurement: 1) perform well in a laboratory setting? 2) provide information in a number of clinical situations? 3) relate to metabolic acidosis? 4) increase workers' confidence? 5) alter therapeutic decisions? 6) result in benefit to patients? 7) result in similar benefits in your own setting? 8) result in benefits which are worth the extra costs?

DATA EXTRACTION AND SYNTHESIS

We concluded that blood lactate measurement in critically ill patients: 1) is accurate in terms of measurement technique but adequate understanding of the (an)aerobic etiology is required for its correct interpretation; 2) provides not only diagnostic but also important prognostic information; 3) should be measured directly instead of estimated from other acid-base variables; 4) has an unknown effect on healthcare workers' confidence; 5) can alter therapeutic decisions; 6) could potentially improve patient outcome when combined with a treatment algorithm to optimize oxygen delivery, but this has only been shown indirectly; 7) is likely to have similar benefits in critical care settings worldwide; and 8) has an unknown cost-effectiveness.

CONCLUSIONS

The use of blood lactate monitoring has a place in risk-stratification in critically ill patients, but it is unknown whether the routine use of lactate as a resuscitation end point improves outcome. This warrants randomized controlled studies on the efficacy of lactate-directed therapy.

Association of physical examination with pulmonary artery catheter parameters in acute lung injury

OBJECTIVE

To correlate physical examination findings, central venous pressure, fluid output, and central venous oxygen saturation with pulmonary artery catheter parameters.

DESIGN

Retrospective study.

SETTING

Data from the multicenter Fluid and Catheter Treatment Trial of the National Institutes of Health Acute Respiratory Distress Syndrome Network.

PATIENTS

Five hundred thirteen patients with acute lung injury randomized to treatment with a pulmonary artery catheter.

INTERVENTIONS

Correlation of physical examination findings (capillary refill time >2 secs, knee mottling, or cool extremities), central venous pressure, fluid output, and central venous oxygen saturation with parameters from a pulmonary artery catheter.

MEASUREMENTS

We determined association of baseline physical examination findings and on-study parameters of central venous pressure and central venous oxygen saturation with cardiac index <2.5 L/min/m2 and mixed venous oxygen saturation <60%. We determined correlation of baseline central venous oxygen saturation and mixed venous oxygen saturation and predictive value of a low central venous oxygen saturation for a low mixed venous oxygen saturation.

MEASUREMENTS AND MAIN RESULTS

Prevalence of cardiac index <2.5 and mixed venous oxygen saturation <60% was 8.1% and 15.5%, respectively. Baseline presence of all three physical examination findings had low sensitivity (12% and 8%), high specificity (98% and 99%), low positive predictive value (40% and 56%), but high negative predictive value (93% and 86%) for cardiac index <2.5 and mixed venous oxygen saturation <60%, respectively. Central venous oxygen saturation <70% predicted a mixed venous oxygen saturation <60% with a sensitivity 84%,specificity 70%, positive predictive value 31%, and negative predictive value of 96%. Low cardiac index correlated with cool extremities, high central venous pressure, and low 24-hr fluid output; and low mixed venous oxygen saturation correlated with knee mottling and high central venous pressure, but these correlations were not found to be clinically useful.

CONCLUSIONS

In this subset of patients with acute lung injury, there is a high prior probability that cardiac index and mixed venous oxygen saturation are normal and physical examination findings of ineffective circulation are not useful for predicting low cardiac index or mixed venous oxygen saturation. Central venous oxygen saturation <70% does not accurately predict mixed venous oxygen saturation <60%, but a central venous oxygen saturation >or=70% may be useful to exclude mixed venous oxygen saturation <60%.

Pro-Con Debate: We should not Measure Cardiac output in Critical Care

The measurement of cardiac output in critical care appears to be increasingly common. However, both the monitoring technologies and the therapeutic approaches they inform have often proved highly controversial. As the range of alternative technologies available continues to increase, it seems worthwhile to question whether this monitoring modality should be used at all. The aim of this pro-con debate is to review the key evidence and to explain the often quite widely differing interpretations placed upon it. The term cardiac output monitoring refers to technology, whose primary purpose is to monitor global blood flow. The principles of the various technologies have been reviewed elsewhere.1

The effect of a quantitative resuscitation strategy on mortality in patients with sepsis: a meta-analysis

OBJECTIVE

Quantitative resuscitation consists of structured cardiovascular intervention targeting predefined hemodynamic end points. We sought to measure the treatment effect of quantitative resuscitation on mortality from sepsis.

DATA SOURCES

We conducted a systematic review of the Cochrane Library, MEDLINE, EMBASE, CINAHL, conference proceedings, clinical practice guidelines, and other sources using a comprehensive strategy.

STUDY SELECTION

We identified randomized control trials comparing quantitative resuscitation with standard resuscitation in adult patients who were diagnosed with sepsis using standard criteria. The primary outcome variable was mortality.

DATA ABSTRACTION

Three authors independently extracted data and assessed study quality using standardized instruments; consensus was reached by conference. Preplanned subgroup analysis required studies to be categorized based on early (at the time of diagnosis) vs. late resuscitation implementation. We used the chi-square test and I to assess for statistical heterogeneity (p < 0.10, I > 25%). The primary analysis was based on the random effects model to produce pooled odds ratios with 95% confidence intervals.

RESULTS

The search yielded 29 potential publications; nine studies were included in the final analysis, providing a sample of 1001 patients. The combined results demonstrate a decrease in mortality (odds ratio 0.64, 95% confidence interval 0.43-0.96); however, there was statistically significant heterogeneity (p = 0.07, I = 45%). Among the early quantitative resuscitation studies (n = 6) there was minimal heterogeneity (p = 0.40, I = 2.4%) and a significant decrease in mortality (odds ratio 0.50, 95% confidence interval 0.37-0.69). The late quantitative resuscitation studies (n = 3) demonstrated no significant effect on mortality (odds ratio 1.16, 95% confidence interval 0.60-2.22).

CONCLUSION

This meta-analysis found that applying an early quantitative resuscitation strategy to patients with sepsis imparts a significant reduction in mortality.

Twenty-eight-day mortality in critically ill surgical patients is an imprecise temporal end-point measure for in-hospital mortality

BACKGROUND

The purpose of this study was to determine the incidence of deaths occurring beyond 28 days in critically ill surgical patients and to identify the proportion of these deaths attributable to the original disease process.

METHODS

Analysis of 1,360 subjects admitted to a surgical intensive care unit during a 2 year period. Demographics, indication(s) for admission, comorbidities, mortality rate, multiorgan failure development, and cause of death was obtained.

RESULTS

Mortality rate in the surgical intensive care unit was 12%. Twenty % of deaths occurred more than 28 days after hospital admission with 76% of deaths related to admission diagnosis. By day 34, 95% of mortalities had occurred.

CONCLUSIONS

The 28-day time period used to assess efficacy of therapeutic interventions and to define mortality in the context of quality audits should be questioned. If these findings are validated in other centers another temporal end point for in-hospital mortality should be considered.

Why are clinicians not embracing the results from pivotal clinical trials in severe sepsis? A bayesian analysis

BACKGROUND

Five pivotal clinical trials (Intensive Insulin Therapy; Recombinant Human Activated Protein C [rhAPC]; Low-Tidal Volume; Low-Dose Steroid; Early Goal-Directed Therapy [EGDT]) demonstrated mortality reduction in patients with severe sepsis and expert guidelines have recommended them to clinical practice. Yet, the adoption of these therapies remains low among clinicians.

OBJECTIVES

We selected these five trials and asked: Question 1--What is the current probability that the new therapy is not better than the standard of care in my patient with severe sepsis? Question 2--What is the current probability of reducing the relative risk of death (RRR) of my patient with severe sepsis by meaningful clinical thresholds (RRR >15%; >20%; >25%)?

METHODS

Bayesian methodologies were applied to this study. Odds ratio (OR) was considered for Question 1, and RRR was used for Question 2. We constructed prior distributions (enthusiastic; mild, moderate, and severe skeptic) based on various effective sample sizes of other relevant clinical trials (unfavorable evidence). Posterior distributions were calculated by combining the prior distributions and the data from pivotal trials (favorable evidence).

MAIN FINDINGS

Answer 1--The analysis based on mild skeptic prior shows beneficial results with the Intensive Insulin, rhAPC, and Low-Tidal Volume trials, but not with the Low-Dose Steroid and EGDT trials. All trials' results become unacceptable by the analyses using moderate or severe skeptic priors. Answer 2--If we aim for a RRR>15%, the mild skeptic analysis shows that the current probability of reducing death by this clinical threshold is 88% for the Intensive Insulin, 62-65% for the Low-Tidal Volume, rhAPC, EGDT trials, and 17% for the Low-Dose Steroid trial. The moderate and severe skeptic analyses show no clinically meaningful reduction in the risk of death for all trials. If we aim for a RRR >20% or >25%, all probabilities of benefits become lower independent of the degree of skepticism.

CONCLUSIONS

Our clinical threshold analysis offers a new bedside tool to be directly applied to the care of patients with severe sepsis. Our results demonstrate that the strength of evidence (statistical and clinical) is weak for all trials, particularly for the Low-Dose Steroid and EGDT trials. It is essential to replicate the results of each of these five clinical trials in confirmatory studies if we want to provide patient care based on scientifically sound evidence.

Pre-Existing Cardiac Disease, Troponin I Elevation and Mortality in Patients with Severe Sepsis and Septic Shock

A prospective, observational study was undertaken to determine the frequency of troponin I elevation and the incidence of pre-existing cardiac disease in patients with severe sepsis and septic shock, and to determine their relationship to mortality.

The setting was the surgical intensive care unit of a tertiary care medical centre. Sixty-six consecutive patients admitted with severe sepsis or septic shock requiring pulmonary artery catheterisation for haemodynamic monitoring were studied. Measurement of troponin I was done at the time of pulmonary artery catheterisation and every six to eight hours if there was ongoing tachycardia, hypotension or arrhythmias requiring treatment. Preexisting cardiac disease was determined from the patient and/or family members as well as from the medical record. Significant cardiac history was defined as prior myocardial infarction; abnormal treadmill report, nuclear medicine study or coronary angiogram; history of congestive heart failure or arrhythmia requiring treatment.

Forty-two patients (64%) had elevated troponin I at study entrance and 23 patients (35%) had pre-existing cardiac disease. History of cardiac disease was associated with reduced cardiac index and oxygen delivery, and a nearly three-fold increase in mortality (44% vs. 16%, P=0.03), irrespective of elevated troponin I levels. Troponin I elevation alone was not associated with increased mortality.

We conclude that pre-existing cardiac disease and elevated troponin I are commonly found in surgical patients with severe sepsis and septic shock. In our study, pre-existing cardiac disease, and not troponin I elevation, was associated with increased mortality.

Developing Quality Measures for Sepsis Care in the ICU

BACKGROUND

Sepsis is associated with increased morbidity, mortality, and costs of care. Although several therapies improve outcomes in patients with sepsis, rigorously developed measures to evaluate quality of sepsis care in the intensive care unit (ICU) are lacking.

METHODS

To select an initial set of candidate measures, in 2003-2004 an interdisciplinary panel reviewed the literature and used a modified nominal group technique to identify interventions that improve outcomes of patients with sepsis in the ICU. Design specifications or explicit definitions for each candidate measure were developed.

RESULTS

Ten potential measures were identified: vancomycin administration, time to vancomycin initiation, broad-spectrum antibiotic administration, time to broad-spectrum antibiotic initiation, blood culture collection, steroid administration, corticotropin stimulation test administration, activated protein C eligibility assessment, activated protein C administration, and vancomycin discontinuation.

DISCUSSION

The identification of potential measures of quality of care for patients with sepsis can help caregivers to focus on evidence-based interventions that improve mortality and to evaluate their current performance. Further work is needed to evaluate the feasibility and validity of the measures.

A PROSPECTIVE RANDOMIZED TRIAL COMPARING OXYGEN DELIVERY VERSUS TRANSCUTANEOUS PRESSURE OF OXYGEN VALUES AS RESUSCITATIVE GOALS

Transcutaneous pressure of oxygen (PtcO2) correlates with arterial pressure of oxygen (PaO2) in nonshock states, but in shock states, PtcO2 approximates cardiac output with no response to increasing fraction of inspired oxygen (FiO2) and PaO2. An incremental change of more than 21 mmHg in PtcO2 in response to an FiO2 of 1.0 (identified as the oxygen challenge test [OCT]) implies adequate tissue perfusion, and lack of response has been associated with mortality. Patients with severe sepsis and septic shock requiring pulmonary artery catheters were randomized to two groups: the oxygen delivery (DO2) group was treated to a DO2 and mixed venous oxygen saturation goals, and the PtcO2 group was treated to achieve an OCT value of 40 mmHg or more. The DO2 (n = 30) and PtcO2 (n = 39) groups were similar in baseline characteristics. Mortality rate was 12 (40%) of 39 for the DO2 group and 5 (13%) of 39 for the PtcO2 group (P = 0.02). Logistic regression analysis of the statistically significant variables between survivors and nonsurvivors demonstrated that inability to reach the PtcO2 goal at 24 h after resuscitation (T24) and a positive cardiac history are associated with mortality (P < 0.001). The area under the receiver operating curve was 0.824 for the OCT at T24. The best OCT value was 25 mmHg at T24 with positive and negative predictive values of 87% and 90%, respectively. Treating patients with severe sepsis/septic shock to an OCT value of 25 mmHg or more may provide a specific end point of resuscitation that may be associated with better survival than resuscitating to the central hemodynamic parameters of DO2 and mixed venous oxygen saturation.

Transcutaneous pressure of oxygen: a noninvasive and early detector of peripheral shock and outcome

A noninvasive tool to recognize early shock would improve outcome by providing prompt recognition of tissue ischemia and precise resuscitation endpoint. The skin is the first tissue bed to vasoconstrict in shock states. Studies have demonstrated that transcutaneous partial pressure of oxygen (PtCO2) increases with higher FiO2 in nonshock states as arterial pressure of oxygen (PaO2) increases, but in shock situations, PtCO2 mirrors changes in cardiac output and oxygen delivery with minimum response to increasing FiO2 and PaO2. This study examined the relationship of hemodynamic variables and the degree of PtCO2 response to FiO2 of 1.0 (identified as the "oxygen challenge test") to mortality and organ failure. This prospective observational study examined 38 patients requiring at least 24 h of cardiac output monitoring for shock resuscitation in the Surgical Intensive Care Unit. Patients were resuscitated to the standard protocol of blood pressure, urine output, oxygen delivery (DO2), and mixed venous O2 (SvO2). Seventy-nine percent of the patients (30/38) with a mean age of 59 +/- 21 years had septic shock or severe sepsis with a 26% mortality (10/38). Measurements included hemodynamic variables, PtCO2, and outcome (mortality and organ failure). In this study, the ability of PtCO2 value to increase by 21 mmHg on a FiO2 of 1.0, at 24 h of resuscitation, divided survivors from nonsurvivors, P <.001. The PtCO2 response to FiO2 may provide an additional noninvasive method of detecting early shock as well as a specific endpoint of resuscitation.

Early goal-directed therapy: a UK perspective

The surviving sepsis campaign developed guidelines in 2003 that were designed to increase physician awareness of sepsis and to develop a series of recommendations for the management of the patient with sepsis. The guidelines had the support of 11 international professional organisations across a variety of specialties, and advocate aggressive, early goal-oriented resuscitation in appropriate patients.

Diagnostic markers of sepsis in the emergency department

Sepsis is defined as the systemic inflammatory response to infection. However, changes in body temperature, heart and respiratory rate and white cell count (the "SIRS" criteria) are not specific enough to identify infected patients in the emergency department. Among many biological parameters, measurement of lactate, central venous oxygen saturation (ScvO2), C-reactive protein (CRP) and procalcitonin (PCT) are of particular interest. Early (within 6h) and goal-directed (ScvO2 > 70%) resuscitation increases survival in severe sepsis and septic shock, particularly in patients with high lactate clearances. CRP and PCT are both useful markers of sepsis but PCT increases earlier, better differentiates infective from non-infective causes of inflammation, more closely correlates with sepsis severity in terms of shock and organ dysfunction and better predicts outcome when followed in time. However, PCT measurement is more costly, time-consuming, and not widespread available. New markers for rapid diagnosis of sepsis (e.g. TREM-1) are under investigation.

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.

Amelioration of hemodynamics and oxygen metabolism by continuous venovenous hemofiltration in experimental porcine pancreatitis

AIM: To investigate the potential role of continuous venovenous hemofiltration (CVVH) in hemodynamics and oxygen metabolism in pigs with severe acute pancreatitis (SAP).

METHODS: SAP model was produced by intraductal injection of sodium taurocholate [4%, 1 mL/kg body weight (BW)] and trypsin (2 U/kg BW). Animals were allocated either to untreated controls as group 1 or to one of two treatment groups as group 2 receiving a low-volume CVVH [20 mL/(kg.h)], and group 3 receiving a high-volume CVVH [100 (mL/kg.h)]. Swan-Ganz catheter was inserted during the operation. Heart rate, arterial blood pressure, cardiac output, mean pulmonary arterial pressure, pulmonary arterial wedge pressure, central venous pressure, systemic vascular resistance, oxygen delivery, oxygen consumption, oxygen extraction ratio, as well as survival of pigs were evaluated in the study.

RESULTS: Survival time was significantly prolonged by low-volume and high-volume CVVHs, which was more pronounced in the latter. High-volume CVVH was significantly superior compared with less intensive treatment modalities (low-volume CVVH) in systemic inflammatory reaction protection. The major hemodynamic finding was that pancreatitis-induced hypotension was significantly attenuated by intensive CVVH (87.4±12.5 kPa vs 116.3±7.8 kPa, P<0.01). The development of hyperdynamic circulatory failure was simultaneously attenuated, as reflected by a limited increase in cardiac output, an attenuated decrease in systemic vascular resistance and an elevation in oxygen extraction ratio.

CONCLUSION: CVVH blunts the pancreatitis-induced cardiovascular response and increases tissue oxygen extraction. The high-volume CVVH is distinctly superior in preventing sepsis-related hemodynamic impairment.

Noninvasive assessment of cardiac output

Improved outcome from shock depends on early detection and correction of circulatory abnormalities. Global cardiac output and oxygen delivery must be adequate and distributed appropriately to meet metabolic demands to prevent the development of multiple organ system dysfunction, prolonged morbidity, and death. Circulatory assessment using standard monitors gives incomplete and sometimes misleading information. This article focuses on the available and emerging technologies that emphasize assessment of blood flow and regional tissue oxygenation.

A novel approach to measure cardiac output noninvasively: a comparison with the thermodilution method on critical care patients

OBJECTIVE

To compare the accuracy and reliability of cardiac output (CO) measurement by a Noninvasive Hemodynamic Analyzer (NHA) to the thermodilution cardiac output (COTD) technique in ICU patients of cardiac condition.

METHOD

ICU retrospective data collected in a 700-bed university-affiliated regional medical center. The data results from 203 patients who required invasive hemodynamic monitoring for clinical and/or surgical management.

RESULTS

The ranges of the two CO measurements were: CO(TD) = 2.06 to 8.8 l/min and CO(NHA) = 2.06 to 8.46 l/min, respectively. The Mean and SD of CO(NHA) = 4.819 l/min +/- 1.053 was near to CO(TD) = 4.902 l/min +/- 1.421. Variance was better for CO(NHA) = 1.110 l/min compared to CO(TD) = 1.421 l/min. Median of CO(NHA) showed 4.813 l/min and CO(TD) = 4.660 l/min. Bias was 0.083 l/min with 95% Confidence Interval (Precision): -0.26 to 0.040, and 95% Limits of Agreement was between -1.661 to 1.827 l/min.

CONCLUSIONS

The results of this retrospective study indicate that the CO(NHA) technique may be a promising screening method. Additional studies are needed to explore its diagnostic trending capability. This noninvasive CO technique has been proven to be clinically accurate and may be applicable for telemedicine applications.

Early goal-directed therapy: An evidence-based review

OBJECTIVE

In 2003, critical care and infectious disease experts representing 11 international organizations developed management guidelines for early goal-directed therapy that would be of practical use for the bedside clinician, under the auspices of the Surviving Sepsis Campaign, an international effort to increase awareness and improve outcome in severe sepsis.

DESIGN

The process included a modified Delphi method, a consensus conference, several subsequent smaller meetings of subgroups and key individuals, teleconferences, and electronic-based discussion among subgroups and among the entire committee.

METHODS

The modified Delphi methodology used for grading recommendations built on a 2001 publication sponsored by the International Sepsis Forum. We undertook a systematic review of the literature graded along five levels to create recommendation grades from A to E, with A being the highest grade. Pediatric considerations to contrast adult and pediatric management are in the article by Parker et al. on p. S591.

CONCLUSION

During the first 6 hrs of resuscitation of sepsis-induced hypoperfusion, specific levels of central venous pressure, mean arterial pressure, urine output, central venous (or mixed venous) oxygen saturation should be targeted. When central venous oxygen saturation remains low, despite achieving central venous pressure and mean arterial pressure targets, packed red blood cells or dobutamine should be considered. Increasing cardiac index to achieve an arbitrarily predefined elevated level is not recommended.

Matching total body oxygen consumption and delivery: a crucial objective?

The strength of the rationale for incorporating total body oxygen consumption (VO(2)) and delivery (DO(2)) into our decision making strategies contrasts with the absence of demonstrated benefits of bedside calculations in clinical practice. This situation mandates a careful reappraisal of the theoretical limitations of bedside calculations of DO(2) and VO(2), including a re-evaluation of the clinical situations in which these calculations are valid. Three levels of complexity can be distinguished when analysing a patient's hemodynamic status: 1) simple cases where investigations can be limited to clinical monitoring, including lactate changes over time; 2) intermediate situations requiring invasive investigations in which continuous monitoring of VO(2)-related variables such as cardiac output and mixed venous oxygen saturation often provide enough information to guide clinical decision; and 3) complex situations where assessment of VO(2) and VO(2)/DO(2) analysis might be recommended. Although studies that support such recommendations are limited they are based on a widely accepted physiological model. VO(2) and DO(2) analysis is also limited by theoretical and technical difficulties. In this article, we discuss the validity of these limitations in the bedside assessment of VO(2) and DO(2), and review data supporting the use of VO(2)/DO(2) analysis in the clinical evaluation of complex cases.

Effects of dopexamine, dobutamine or dopamine on prolactin and thyreotropin serum concentrations in high-risk surgical patients

OBJECTIVES

Catecholamines are often used for optimisation of cardiac index and oxygen delivery in high-risk surgical patients; however, infusions of dopamine and dopexamine are associated with dose-dependent hypophysiotropic and thyreotropic properties. The objective was to compare endocrine effects of equipotent inotropic doses of dopexamine, dobutamine and dopamine on prolactin and thyreotropin release perioperatively.

DESIGN

A prospective, randomised, blinded clinical trial.

SETTING

Adult surgical intensive care unit in a university hospital.

PATIENTS

Thirty male patients (ASA III) undergoing elective major abdominal surgery.

INTERVENTIONS

Patients were randomised to receive dopexamine (DX, n=10), dobutamine (DO, n=10) or dopamine (DA, n=10) on the first postoperative day for 8 h.

MEASUREMENTS AND RESULTS

All patients received a catecholamine infusion in doses adjusted to increase cardiac index by 35% within the first hour. Blood samples were obtained and prolactin and thyreotropin serum concentrations were determined by radioimmunoassays. Mean doses of dopexamine, dobutamine and dopamine used were 0.73+/-0.27, 4.06+/-1.95 and 5.0+/-1.84 micro g kg(-1)min(-1), respectively. Cardiac index was increased by 36% (DX group), 38% (DO group) and 38% (DA group). Alterations of oxygen delivery and oxygen consumption were not significantly different between the study groups. Dopexamine and dobutamine had no hypophysiotropic effects. In contrast, dopamine suppressed prolactin and thyreotropin secretion with a maximal effect after 4 h. After dopamine withdrawal, a rebound release of prolactin and thyreotropin was observed.

CONCLUSIONS

In high-risk surgical patients dopexamine or dobutamine produced fewer effects on prolactin and thyreotropin serum concentrations in comparison with DA when used in equivalent dosages.

The International Sepsis Forum's frontiers in sepsis: High cardiac output should not be maintained in severe sepsis

Abnormal oxygen utilisation is one of the features of septic shock. Some studies have observed that patients that survive septic shock tend to have higher cardiac output and oxygen delivery compared to those that do not. It has been proposed that higher than normal (or "supra-normal") levels of cardiac output and oxygen deliver should be the goal in the management of septic shock. However, randomised controlled trials have not been able to validate that such a goal provides a mortality or morbidity advantage. In this commentary we discuss the various reasons put forward by the proponents of this strategy and review the available evidence.

Positive end-expiratory pressure alters intracranial and cerebral perfusion pressure in severe traumatic brain injury

BACKGROUND

Optimizing intracranial pressure (ICP) and cerebral perfusion pressure (CPP) is important in the management of severe traumatic brain injury (TBI). In trauma patients with TBI and respiratory dysfunction, positive end-expiratory pressure (PEEP) is often required to support oxygenation. Increases in PEEP may lead to reduced CPP. We hypothesized that increases in PEEP are associated with compromised hemodynamics and altered cerebral perfusion.

METHODS

Twenty patients (mean Injury Severity Score of 28) with TBI (Glasgow Coma Scale score < 8) were examined. All required simultaneous ICP and hemodynamic monitoring. Data were categorized on the basis of PEEP levels. Variables included central venous pressure, pulmonary artery occlusion pressure, cardiac index, oxygen delivery, and oxygen consumption indices. Differences were assessed using Kruskal-Wallis analysis of variance.

RESULTS

Data were expressed as mean +/- SE. As PEEP increased from 0 to 5, to 6 to 10 and 11 to 15 cm H O, ICP decreased from 14.7 +/- 0.2 to 13.6 +/- 0.2 and 13.1 +/- 0.3 mm Hg, respectively. Concurrently, CPP improved from 77.5 +/- 0.3 to 80.1 +/- 0.5 and 78.9 +/- 0.7 mm Hg. As central venous pressure (5.9 +/- 0.1, 8.3 +/- 0.2, and 12.0 +/- 0.3 mm Hg) and pulmonary artery occlusion pressure (8.3 +/- 0.2, 11.6 +/- 0.4, and 15.6 +/- 0.4 mm Hg) increased with rising levels of PEEP, cardiac index, oxygen delivery, and oxygen consumption indices remained unaffected. Overall mortality was 30%.

CONCLUSION

In trauma patients with severe TBI, the strategy of increasing PEEP to optimize oxygenation is not associated with reduced cerebral perfusion or compromised oxygen transport.

Meta-analysis of hemodynamic optimization in high-risk patients

OBJECTIVE

The aim of this evidence-based report was to review pertinent randomized controlled studies that describe hemodynamic goals in acute, critically ill patients and to evaluate outcome of resuscitation therapy in association with physiologic, clinical, and therapeutic influences.

METHODS

MEDLINE was the source of randomized controlled studies written in English. The inclusion criteria were acutely ill, high-risk elective surgery, trauma, and septic patients. The goals of therapy were to resuscitate to either normal or supranormal values; the latter were described as a cardiac index of >4.5 L x min(-1) x m(-2), pulmonary artery occlusion pressure of <18 mm Hg, oxygen delivery of >600 mL x min(-1) x m(-2), and oxygen consumption of >170 mL x min(-1) x m(-2). The outcome criterion was survival or death. We found 21 randomized clinical trials described in 20 articles. The studies were divided into groups based on the time that goals were implemented (i.e., "early," 8 to 12 hrs postoperatively or before organ failure, vs. "late," or after onset of organ failure) and the severity of illness, determined by the control group mortality as >20% (12 studies) or <15% (nine studies).

RESULTS

In severely ill patients (control mortalities group >20%), six studies had a 23% mortality difference (p <.05) between the control and protocol groups with early optimization, but seven studies optimized after the development of organ failure did not have significantly improved mortality. Moreover, outcome was not significantly improved in less severely ill patients (control mortalities group <15%) and normal values as goals or when therapy did not improve oxygen delivery.

CONCLUSION

Review of 21 randomized controlled trials with various approaches to treatment revealed statistically significant mortality reductions, with hemodynamic optimization, when patients with acute critical illness were treated early to achieve optimal goals before the development of organ failure, when there were control group mortalities of >20% and when therapy produced differences in oxygen delivery between the control and protocol groups.

The effect of neuromuscular blockade on oxygen supply, consumption, and total chest compliance in patients with high oxygen requirements undergoing mechanical ventilation

We investigated the effects of neuromuscular blockade with atracurium on oxygen consumption, oxygen delivery and total chest compliance in 20 sedated intensive care patients who required mechanical ventilation with an inspired oxygen fraction of at least 0.6. The reverse Fick method was used to measure oxygen consumption. Total chest compliance was measured from the ventilator pneumotachograph and pressure transducer. Measurements were made before neuromuscular blockade, at a standard level of neuromuscular blockade, and after demonstrated recovery of neuromuscular function. There was no statistical difference in any of the parameters measured. However there were large changes in oxygen consumption (range -35% to +17%) and total chest compliance (range -19.7% to +9.7%) in individuals. We conclude that in the setting of critical oxygenation, neuromuscular blockade cannot be assumed to reduce oxygen requirements or improve total lung compliance. If, however, neuromuscular blockade is selected as an adjunct to therapy, we recommend that the indices of oxygenation are calculated.

Infusion of methylene blue in human septic shock: a pilot, randomized, controlled study

OBJECTIVE

To evaluate the effects of continuous infusion of methylene blue (MB), an inhibitor of the nitric oxide pathway, on hemodynamics and organ functions in human septic shock.

DESIGN

Prospective, randomized, controlled, open-label, pilot study.

SETTING

Multidisciplinary intensive care unit of a university hospital.

PATIENTS

Twenty patients with septic shock diagnosed <24 hrs before randomization.

INTERVENTIONS

Patients were randomized 1:1 to receive either MB (MB group, n = 10) or isotonic saline (control group, n = 10), adjunctive to conventional treatment. MB was administered as an intravenous bolus injection (2 mg/kg), followed 2 hrs later by infusion at stepwise increasing rates of 0.25, 0.5, 1, and 2 mg/kg/hr that were maintained for 1 hr each. During infusion, mean arterial pressure was maintained between 70 and 90 mm Hg, while attempting to reduce concurrent adrenergic support.

MEASUREMENTS AND MAIN RESULTS

Hemodynamics and organ function variables were assessed over a 24-hr period, and the survival rate at day 28 was noted. Infusion of MB prevented the stroke volume and the left-ventricular stroke work indexes from falling and increased mean arterial pressure. Compared with the control group, MB reduced the requirement for norepinephrine, epinephrine, and dopamine by as much as 87%, 81%, and 40%, respectively. Oxygen delivery remained unchanged in the MB group and decreased in the control group. MB also reduced the body temperature and the plasma concentration of nitrates/nitrites. Leukocytes and organ function variables such as bilirubin, alanine aminotransferase, urea, and creatinine were not significantly affected. Platelet count decreased in both groups. Five patients treated with MB survived vs. three patients receiving conventional treatment.

CONCLUSIONS

In human septic shock, continuously infused MB counteracts myocardial depression, maintains oxygen transport, and reduces concurrent adrenergic support. Infusion of MB appears to have no significant adverse effects on the selected organ function variables.