In this paper we present a case study of interactive visual analysis and exploration of a large ICU data set. The data consists of patients’ records containing scalar data representing various patients’ parameters (e.g. gender, age, weight), and time series data describing logged parameters over time (e.g. heart rate, blood pressure). Due to the size and complexity of the data, coupled with limited time and resources, such ICU data is often not utilized to its full potential, although its analysis could contribute to a better understanding of physiological, pathological and therapeutic processes, and consequently lead to an improvement of medical care. During the exploration of this data we identified several analysis tasks and adapted and improved a coordinated multiple views system accordingly. Besides a curve view which also supports time series with gaps, we introduced a summary view which allows an easy comparison of subsets of the data and a box plot view in a coordinated multiple views setup. Furthermore, we introduced an inverse brush, a secondary brush which automatically selects non-brushed items, and updates itself accordingly when the original brush is modified. The case study describes how we used the system to analyze data from 1447 patients from the ICU at Guy’s & St. Thomas’ NHS Foundation Trust in London. We were interested in the relationship between serum sodium concentration, its rate of change and their effect on ICU mortality rates. The interactive visual analysis led us to findings which were fascinating for medical experts, and which would be very difficult to discover using conventional analysis methods usually applied in the medical field. The overall feedback from domain experts (coauthors of the paper) is very positive.

In the previous issue of Critical Care, Takala and colleagues presented the results of a multicenter study to investigate whether the early presence of less invasive hemodynamic monitoring improves outcome in patients admitted with hemodynamic instability to the intensive care unit. The authors' results suggest that it makes no difference. We discuss these findings and compare them to the literature on early goal-directed therapy in which monitors are used early but with a protocol.

Original research contributions published in Critical Care in 2008 in the fields of respirology and critical care medicine are summarized. Eighteen articles were grouped into the following categories: acute lung injury and acute respiratory distress syndrome, mechanical ventilation, mechanisms of ventilator-induced lung injury, and tracheotomy decannulation and non-invasive ventilation.

Objectives: To establish whether perioperative low-dose dopexamine infusion (≤1 μg/kg/min) is associated with a reduction in mortality and duration of hospital stay following major surgery. Data Source: Medline, EMBASE, CINAHL, Cochrane Library, Google Scholar, and reference lists. Study Selection: Two reviewers independently screened studies for inclusion, assessed trial quality, and extracted data. Eligible trials were randomized controlled trials comparing dopexamine infusion to control treatment. Data are reported as odds ratios (ORs) or hazard ratios (HRs) with 95% confidence intervals. Data Extraction: Systematic review and meta-regression analysis of individual patient data. Data Synthesis: Five studies fulfilled the inclusion criteria. Analysis of pooled data from high- and low-dose dopexamine groups identified a reduction in duration of hospital stay (median 14 vs. 15 days; HR 0.85 [0.73–0.91]; p = .03) but no improvement in mortality (9.1% vs. 12.3%; OR 0.78 [0.31–1.99]; p = .61). However, low-dose dopexamine was associated with a 50% reduction in 28-day mortality (6.3% vs. 12.3%; OR 0.50 [0.28–0.88]; p = .016) as well as a reduced duration of stay (median 13 vs. 15 days; HR 0.75 [0.64–0.88]; p = .0005). When high-dose dopexamine groups were compared with controls, there was no difference in either mortality (OR 1.06 [0.60–1.87]; p = .85) or duration of stay (HR 1.04 [0.94–1.16]; p = .36). Conclusions: For pooled data describing perioperative dopexamine infusion at all doses, there was an improvement in duration of hospital stay but no survival benefit. However, at low doses, dopexamine was associated with improved survival and reduced duration of stay. Further clinical trials are warranted to confirm this observation.

Despite studies clearly demonstrating significant benefit from increasing oxygen delivery in the peri-operative period in high risk surgical patients, the technique has not been widely accepted. This is due to a variety of reasons, including non-availability of beds, particularly in the pre-operative period, and the requirement of inserting a pulmonary artery catheter. There are now data that suggest that increasing oxygen delivery post-operatively using a nurse-led protocol based on pulse contour analysis leads to a major improvement in outcome with reduction in infection rate and length of hospital stay.

INTRODUCTION:Risk stratification of severely ill patients remains problematic, resulting in increased interest in potential circulating markers, such as cytokines, procalcitonin and brain natriuretic peptide. Recent reports have indicated the usefulness of plasma DNA as a prognostic marker in various disease states such as trauma, myocardial infarction and stroke. The present study assesses the significance of raised levels of plasma DNA on admission to the intensive care unit (ICU) in terms of its ability to predict disease severity or prognosis.METHODS:Fifty-two consecutive patients were studied in a general ICU. Blood samples were taken on admission and were stored for further analysis. Plasma DNA levels were estimated by a PCR method using primers for the human beta-haemoglobin gene.RESULTS:Sixteen of the 52 patients investigated died within 3 months of sampling. Nineteen of the 52 patients developed either severe sepsis or septic shock. Plasma DNA was higher in ICU patients than in healthy controls and was also higher in patients who developed sepsis (192 (65-362) ng/ml versus 74 (46-156) ng/ml, P = 0.03) or who subsequently died either in the ICU (321 (185-430) ng/ml versus 71 (46-113) ng/ml, P < 0.001) or in hospital (260 (151-380) ng/ml versus 68 (47-103) ng/ml, P < 0.001). Plasma DNA concentrations were found to be significantly higher in patients who died in the ICU. Multiple logistic regression analysis determined plasma DNA to be an independent predictor of mortality (odds ratio, 1.002 (95% confidence interval, 1.0-1.004), P = 0.05). Plasma DNA had a sensitivity of 92% and a specificity of 80% when a concentration higher than 127 ng/ml was taken as a predictor for death on the ICU.CONCLUSION:Plasma DNA may be a useful prognostic marker of mortality and sepsis in intensive care patients.

INTRODUCTION:Little is known about mortality rates following general surgical procedures in the United Kingdom. Deaths are most common in the 'high-risk' surgical population consisting mainly of older patients, with coexisting medical disease, who undergo major surgery. Only limited data are presently available to describe this population. The aim of the present study was to estimate the size of the high-risk general surgical population and to describe the outcome and intensive care unit (ICU) resource use.METHODS:Data on inpatient general surgical procedures and ICU admissions in 94 National Health Service hospitals between January 1999 and October 2004 were extracted from the Intensive Care National Audit & Research Centre database and the CHKS database. High-risk surgical procedures were defined prospectively as those for which the mortality rate was 5% or greater.RESULTS:There were 4,117,727 surgical procedures; 2,893,432 were elective (12,704 deaths; 0.44%) and 1,224,295 were emergencies (65,674 deaths; 5.4%). A high-risk population of 513,924 patients was identified (63,340 deaths; 12.3%), which accounted for 83.8% of deaths but for only 12.5% of procedures. This population had a prolonged hospital stay (median, 16 days; interquartile range, 9-29 days). There were 59,424 ICU admissions (11,398 deaths; 19%). Among admissions directly to the ICU following surgery, there were 31,633 elective admissions with 3,199 deaths (10.1%) and 24,764 emergency admissions with 7,084 deaths (28.6%). The ICU stays were short (median, 1.6 days; interquartile range, 0.8-3.7 days) but hospital admissions for those admitted to the ICU were prolonged (median, 16 days; interquartile range, 10-30 days). Among the ICU population, 40.8% of deaths occurred after the initial discharge from the ICU. The highest mortality rate (39%) occurred in the population admitted to the ICU following initial postoperative care on a standard ward.CONCLUSION:A large high-risk surgical population accounts for 12.5% of surgical procedures but for more than 80% of deaths. Despite high mortality rates, fewer than 15% of these patients are admitted to the ICU.

Introduction Goal-directed therapy (GDT) has been shown to improve outcome when commenced before surgery. This requires pre-operative admission to the intensive care unit (ICU). In cardiac surgery, GDT has proved effective when commenced after surgery. The aim of this study was to evaluate the effect of post-operative GDT on the incidence of complications and duration of hospital stay in patients undergoing general surgery.Methods This was a randomised controlled trial with concealed allocation. High-risk general surgical patients were allocated to post-operative GDT to attain an oxygen delivery index of 600 ml min(-1) m(-2) or to conventional management. Cardiac output was measured by lithium indicator dilution and pulse power analysis. Patients were followed up for 60 days.Results Sixty-two patients were randomised to GDT and 60 patients to control treatment. The GDT group received more intravenous colloid (1,907 SD +/- 878 ml versus 1,204 SD +/- 898 ml; p < 0.0001) and dopexamine ( 55 patients (89%) versus 1 patient (2%); p < 0.0001). Fewer GDT patients developed complications ( 27 patients (44%) versus 41 patients (68%); p = 0.003, relative risk 0.63; 95% confidence intervals 0.46 to 0.87). The number of complications per patient was also reduced (0.7 SD +/- 0.9 per patient versus 1.5 SD +/- 1.5 per patient; p = 0.002). The median duration of hospital stay in the GDT group was significantly reduced ( 11 days ( IQR 7 to 15) versus 14 days ( IQR 11 to 27); p = 0.001). There was no significant difference in mortality ( seven patients (11.3%) versus nine patients (15%); p = 0.59).Conclusion Post-operative GDT is associated with reductions in post-operative complications and duration of hospital stay. The beneficial effects of GDT may be achieved while avoiding the difficulties of pre-operative ICU admission.

Despite recent interest in measurement of central venous oxygen saturation (ScvO2), there are no published data describing the pattern of ScvO2 changes after major general surgery or any relationship with outcome.

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.

Automated online tonometry displays a rapid, semicontinuous measurement of gastric-to-endtidal carbon dioxide (Pr-etCO2) as an index of gastrointestinal perfusion during surgery. Its use to predict postoperative outcome has not been studied in general surgery patients. We, therefore, studied ASA physical status III-IV patients operated on for elective surgery under general anesthesia and a planned duration of >2 h in a European, multicenter study. As each center was equipped with only 1 tonometric monitor, a randomization was performed if more than one patient was eligible the same day. Patients not monitored with tonometry were assessed only for follow-up. The main outcome measure was the assessment of postoperative functional recovery delay (FRD) on day 8. Among the 290 patients studied, 34% had FRD associated with a longer hospital stay. The most common FRDs were gastrointestinal (45%), infection (39%), and respiratory (35%). In those monitored with tonometry (n = 179), maximum Pr-etCO2 proved to be the best predictor increasing the probability of FRD from 34% for all patients to 65% at a cut-off of 21 mm Hg (2.8kPa) (sensitivity 0.27, specificity 0.92, positive predictive value 64%, negative predictive value 70%). We conclude that intraoperative Pr-etCO2 measurement may be a useful prognostic index of postoperative morbidity.

The aims of this study were to look for the variability in the treatment of circulatory shock and to assess the extent to which this variability was reduced by pulmonary artery catheterization (PAC). At three international conferences in 1997-1998 (European Society of Critical Care Medicine, French Language Society for Critical Care [Société de Réanimation de Langue Française], and Society of Critical Care Medicine), a real-life clinical case was discussed in meetings among physicians and a panel of experts, with assistance from an expert computer program. A total of 417 physicians took part in the discussions. Following the clinical presentation, only 38% of physicians suggested the same treatment as the experts, and 35% suggested potentially harmful treatments. Complete hemodynamic data from PAC significantly decreased the range of suggested treatments, improved agreement among physicians themselves as well as the agreement between physicians and experts, and decreased the number of potentially harmful propositions. However, whereas almost 80% of participants finally agreed on the treatment after one to three invasive hemodynamic sets of measurements, at least 10% persisted in suggesting potentially harmful treatments. PAC improved interphysician agreement, but our data suggest that yet greater agreement could be achieved by improving the theoretical training of practitioners.

Objective: To compare the survival and clinical outcomes of critically ill patients treated with the use of a pulmonary artery catheter (PAC) to those treated without the use of a PAC. Design: Prospective, randomised, controlled, clinical trial from October 1997 to February 1999. Setting: Adult intensive care unit at a large teaching hospital. Patients: Two hundred one critically ill patients were randomised either to a PAC group (n=95) or the control group (n=106). One patient in the control group was withdrawn from the study and five patients in the PAC group did not receive a PAC. All participants were available for follow-up. Interventions: Participants were assigned to be managed either with the use of a PAC (PAC group) or without the use of a PAC (control group). Main outcome measures: Survival to 28 days, intensive care and hospital length of stay and organ dysfunction were compared on an intention-to-treat basis and also on a subgroup basis for those participants who successfully received a PAC. Results: There was no significant difference in mortality between the PAC group [46/95 (47.9%)] and the control group [50/106 (47.6)] (95% confidence intervals for the difference –13 to 14%, p>0.99). The mortality for participants who had management decisions based on information derived from a PAC was 41/91 (45%, 95% confidence intervals –11 to 16%, p=0.77). The PAC group had significantly more fluids in the first 24 h (4953 (3140, 7000) versus 4292 (2535, 6049) ml) and an increased incidence of renal failure (35 versus 20% of patients at day 3 post randomisation p<0.05) and thrombocytopenia (p<0.03). Conclusions: These results suggest that the PAC is not associated with an increased mortality.

STUDY OBJECTIVESTo evaluate the acute physiology, age, chronic health evaluation III (APACHE III) scoring system in the context of general adult ICUs in the United Kingdom.DESIGNProspective, noninterventional, cohort study.SETTINGSeventeen general adult ICUs in a discrete area of southwest England.PATIENTS12,793 patients admitted between April 1, 1993 and December 31, 1995.MEASUREMENTSSociodemographic and severity-of-illness data were collected for all patients admitted to the study units. Formal goodness-of-fit tests were applied and observed mortality was compared with that predicted by using the APACHE III system.RESULTSFor the group of ICUs as a whole, the risk-adjusted standardized mortality ratio (SMR) was 1.23 (95% confidence intervals, 1.12-1.25). For 11 out of 17 ICUs, the SMR was significantly greater than unity (p < 0.05). Calibration, as tested by Hosmer-Lemeshow statistics, was poor (H2 = 312.54; C2 = 332.85; df = 8; p < 0.01); however, model discrimination was good with a total correct classification rate of 82.9% and an area under the receiver operating characteristic curve of 0.89.CONCLUSIONSThe excess mortality observed after case-mix adjustment using the APACHE III system in this study may be the result of either poor intensive care performance as compared with the United States or a failure of the APACHE III equation to fit the UK data.