Systemic inflammatory response syndrome, sepsis, severe sepsis and septic shock: incidence, morbidities and outcomes in surgical ICU patients

Non-neurologic organ dysfunction in severe traumatic brain injury

OBJECTIVE

To describe the incidence of non-neurologic organ dysfunction and its association with outcome in patients with severe traumatic brain injury admitted to intensive care.

DESIGN

Observational cohort study.

SETTING

Foothills Medical Centre, which is the only neurosurgical service in southern Alberta (population approximately 1.3 million).

PATIENTS

Patients were 209 consecutive patients with severe traumatic brain injury.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Non-neurologic organ dysfunction was measured by the maximum modified multiple organ dysfunction score. Organ system failure was defined as a component score of >/=3 on any day during the patient's intensive care unit stay. One hundred and eighty-five patients (89%) developed dysfunction of at least one non-neurologic organ system. Ninety-six organ system failures were identified in 74 patients (35%). Respiratory failure was the most common non-neurologic organ system failure, occurring in 23% of patients, whereas cardiovascular failure occurred in 18%. Eight patients (4%) had failure of the coagulation system. One patient had renal failure, whereas no patient developed hepatic failure. In a multivariate model, non-neurologic organ dysfunction was independently associated with hospital mortality (odds ratio for hospital mortality, 1.63; 95% confidence interval, 1.34, 1.98 for one maximum modified multiple organ dysfunction score point). Non-neurologic organ dysfunction was also independently associated with dichotomized Glasgow Outcome Score, as a measure of neurologic outcome (odds ratio for unfavorable neurologic outcome, 1.53; 95% confidence interval, 1.22, 1.98 for one maximum modified multiple organ dysfunction score point). The timing of the organ dysfunction did not appear to be important in the prediction of outcome.

CONCLUSIONS

Non-neurologic organ dysfunction is common in patients with severe traumatic brain injury and is independently associated with worse outcome.

Effect of dexamethazone on hepatic vascular response in experimental sepsis

BACKGROUND

The aim of the present study was to evaluate the effect of dexamethasone-pretreatment on the hepatic artery and portal vein of septic rats, which were generated by lipopolisaccarides (LPS) intraperitoneal injection.

METHOD

Thirty-six albino Wistar rats were used and constructed as LPS (n = 12), control (n = 12), dexamethazone-pretreatment (n = 6) and dexamethazone-control (n = 6) groups. Hepatic artery and portal vein rings were excised and placed in Krebs-Henseleit solution. Vessel rings were contracted with phenylephrine adding to the organ chamber in cumulative doses. Then the contraction-response curves were drawn.

RESULTS

In the LPS group, phenylephrine evoked contractions were reduced in both hepatic artery and portal vein rings in comparison to the control group. In the dexamethasone-control group, phenylephrine-evoked contractions were increased but not significantly. Dexamethasone-pretreatment increased the phenylephrine-evoked contractions close to the values of control group for both types of rings.

CONCLUSIONS

Dexamethasone pretreatment corrected the vascular hyporeactivity to phenyleprine in isolated portal vein and hepatic artery rings prepared from the LPS treated rats in experimental sepsis. This might have occurred as a result of inhibition of inducible nitric oxide synthase expression.

Systemic Inflammatory Response and Progression to Severe Sepsis in Critically Ill Infected Patients

RATIONALE

The systemic inflammatory response syndrome has low specificity to identify infected patients at risk of worsening to severe sepsis or shock.

OBJECTIVE

To examine the incidence of and risk factors for worsening sepsis in infected patients.

METHODS

A 1-year inception cohort study in 28 intensive care units of patients (n = 1,531) having a first episode of infection on admission or during the stay.

MEASUREMENTS AND MAIN RESULTS

The cumulative incidence of progression to severe sepsis or shock was 20% and 24% at Days 10 and 30, respectively. Variables independently associated (hazard ratio [HR]) with worsening sepsis included: temperature higher than 38.2 degrees C (1.6), heart rate greater than 120/minute (1.3), systolic blood pressure higher than 110 mm Hg (1.5), platelets higher than 150 x 109/L (1.5), serum sodium higher than 145 mmol/L (1.5), bilirubin higher than 30 mumol/L (1.3), mechanical ventilation (1.5), and five variables characterizing infection (pneumonia [HR 1.5], peritonitis [1.5], primary bacteremia [1.8], and infection with gram-positive cocci [1.3] or aerobic gram-negative bacilli [1.4]). The 12 weighted variables were included in a score (Risk of Infection to Severe Sepsis and Shock Score, range 0-49), summarized in four classes of "low" (score 0-8) and "moderate" (8.5-16) risk (9% and 17% probability of worsening, respectively), and of "high" (16.5-24) and "very high" (score > 24) risk (31% and 55% probability, respectively).

CONCLUSIONS

One of four patients presenting with infection/sepsis worsen to severe sepsis or shock. A score estimating this risk, using objectively defined criteria for systemic inflammatory response syndrome, could be used by physicians to stratify patients for clinical management and to test new interventions.

Plasma concentration of procalcitonin and systemic inflammatory response syndrome after colorectal surgery

BACKGROUND

To study whether plasma concentrations of procalcitonin (PCT), interleukin-6 (IL-6), complement 3a (C3a), C-reactive protein and white blood cell count (WBC) correlate with the presence of systemic inflammatory response syndrome (SIRS) during the early post-operative period after major colorectal surgery.

METHODS

Prospective, observational study during the first 24 h post-operatively. The setting for the study was the operating theatre and the recovery unit at the university hospital. Fifty consecutive patients, operated on electively with major resection of the large bowel or rectum. PCT levels increased significantly to the maximum level 18 h postoperatively. PCT levels were significantly higher in the SIRS group in comparison to the non-SIRS group of patients 6 and 12 h after surgery (P < 0.05). The IL-6 levels were increased directly after the surgery and then decreased gradually in both study groups. Twenty-four hours after the surgery, C3a levels decreased and then returned to normal levels. Twenty-four hours post-operatively, patients with SIRS had a higher plasma concentration of C3a compared with patients without SIRS (P < 0.05). CRP and WBC increased during the study period in both groups (P < 0.05).

CONCLUSIONS

During the early post-operative period after uncomplicated major abdominal surgery, SIRS was reflected by the increase in plasma PCT and C3a concentrations. IL-6, CRP and WBC increased to the same extend in both the SIRS and the non-SIRS group of patients.

One-year mortality of bloodstream infection-associated sepsis and septic shock among patients presenting to a regional critical care system

OBJECTIVE

The long-term mortality outcome associated with sepsis and septic shock has not been well defined in a nonselected critically ill population. This study investigated the occurrence and the role of bloodstream infection (BSI) associated sepsis and septic shock at time of intensive care unit (ICU) admission on the 1-year mortality of patients admitted to a regional critical care system.

DESIGN AND SETTING

Population-based inception cohort in all adult multidisciplinary and cardiovascular ICUs in the Calgary Health Region (population approx. 1 million) between 1 July 1999 and 31 March 2002.

PATIENTS AND PARTICIPANTS

Adults (>/=18 years; n=4,845) who had at least one ICU admission to CHR ICUs.

RESULTS

In 251 (5%) patients there was BSI-associated sepsis at presentation to ICU, and 159 of these also had septic shock. The 28-day, 90-day, and 1-year mortality rates overall were 18%, 21%, and 24%: 23%, 30%, and 36% for BSI-associated sepsis without shock, and 51%, 57%, and 61% with shock, respectively. Surgical diagnosis, BSI-associated sepsis, and increasing age were independently associated with late (28-day to 1-year) mortality whereas higher APACHE II and TISS scores were associated with reduced odds in logistic regression analysis.

CONCLUSIONS

BSI-associated sepsis and septic shock are associated with increased risk of mortality persisting after 28-days up to 1 year or more. Follow-up duration beyond 28 days better defines the burden of illness associated with these syndromes.

Heme oxygenase modulates hepatic leukocyte sequestration via changes in sinusoidal tone in systemic inflammation in mice

Heme oxygenase (HO) modulates the accumulation of leukocytes within the liver during the early stages of a systemic inflammatory response syndrome (SIRS), but the anti-inflammatory mechanism(s) remain to be tested. The influence of HO on the adhesion molecule expression within the liver and on circulating leukocytes was assessed. In addition, the effect of HO and nitric oxide synthase (NOS) on the liver microcirculation was tested. Mice were subjected to 1 h bilateral hindlimb ischemia followed by 3 h of reperfusion, at which time blood samples and the liver were harvested and adhesion molecule expression determined (ICAM-1, CD49d and CD11b). Direct measures of sinusoidal diameter and estimates of volumetric blood flow were obtained using intravital microscopy. HO was specifically induced and inhibited by hemin and chromium mesoporphyrin (CrMP), respectively, whereas NOS was inhibited by N-nitro-L-arginine methyl ester (L-NAME). ICAM-1 expression was increased following hindlimb ischemia-reperfusion. Hemin caused only a modest, but significant decrease in ICAM-1 expression, whereas inhibition of HO had no effect. However, HO inhibition significantly reduced sinusoidal diameters and volumetric flow and such vessels were correlated with significantly increased numbers of stationary leukocytes. Inhibition of NOS had no effect on sinusoidal diameter or volumetric flow. In conclusion, the anti-inflammatory benefits afforded by HO activity within the liver appear to involve the control of sinusoidal diameter and volumetric blood flow rather than altered adhesion molecule expression during the early stages of SIRS.

CHRONIC ALCOHOLISM CAUSES DELETERIOUS CONDITIONING OF INNATE IMMUNITY

AIMS

To examine the immune consequences of chronic alcoholism in man, in relation to the known association between alcoholism and raised incidence and severity of infections.

METHODS

In 36 alcoholics without liver disease, at the point of commencing withdrawal from alcohol, the following measures of immune competence were measured: the immunophenotypes of cells, acute phase proteins, the endotoxin-neutralizing capacity (ENC) of the serum, titers of anti-lipopolysaccharide (LPS) antibodies, and ex vivo cytokine inducibility in T cells and monocytes (TNFalpha, IL1beta, IL1RA, IL4, IL6, IL8, IL10 and IL12). The results were compared to those from healthy volunteers (day controls). Measures were repeated after 8-13 days of abstinence.

RESULTS

LPS-binding protein (LBP) and soluble CD14 (sCD14) were significantly increased in patients' sera at the outset of withdrawal, whereas reduced titers of anti-LPS IgG (P = 0.012) and a reduced ENC (P = 0.001) were measured. Only ENC rapidly returned to normal values after withdrawal therapy. Cytokine induction with phorbol ester showed no significant alterations in patients' T cells. Patients' monocytes, however, responded to LPS stimulation with enhanced IL1beta-, but reduced TNFalpha- and IL12-production (P = 0.004, P = 0.0042 and P = 0.001, respectively). While IL1- and TNFalpha-responses normalized after the withdrawal period, impairment of the IL12 response persisted throughout the observation period of 2 weeks.

CONCLUSIONS

Alcoholism results in a prolonged LPS-mediated hypoinflammatory conditioning of the innate but not the adaptive immune system, which is not reversed immediately after withdrawal. This alcohol-induced status of the immune system predisposes to infections and sepsis by blunting initial response to the pathogens.

Nosocomial bloodstream infection and clinical sepsis

Primary bloodstream infection (BSI) is a leading, preventable infectious complication in critically ill patients and has a negative impact on patients’ outcome. Surveillance definitions for primary BSI distinguish those that are microbiologically documented from those that are not. The latter is known as clinical sepsis, but information on its epidemiologic importance is limited. We analyzed prospective on-site surveillance data of nosocomial infections in a medical intensive care unit. Of the 113 episodes of primary BSI, 33 (29%) were microbiologically documented. The overall BSI infection rate was 19.8 episodes per 1,000 central-line days (confidence interval [CI] 95%, 16.1 to 23.6); the rate fell to 5.8 (CI 3.8 to 7.8) when only microbiologically documented episodes were considered. Exposure to vascular devices was similar in patients with clinical sepsis and patients with microbiologically documented BSI. We conclude that laboratory-based surveillance alone will underestimate the incidence of primary BSI and thus jeopardize benchmarking.

Adult-population incidence of severe sepsis in Australian and New Zealand intensive care units

OBJECTIVE

To determine the population incidence and outcome of severe sepsis occurring in adult patients treated in Australian and New Zealand intensive care units (ICUs), and compare with recent retrospective estimates from the USA and UK.

DESIGN

Inception cohort study.

SETTING

Twenty-three closed multi-disciplinary ICUs of 21 hospitals (16 tertiary and 5 university affiliated) in Australia and New Zealand.

PATIENTS

A total of 5878 consecutive ICU admission episodes.

MEASUREMENTS AND RESULTS

Main outcome measures were population-based incidence of severe sepsis, mortality at ICU discharge, mortality at 28 days after onset of severe sepsis, and mortality at hospital discharge. A total of 691 patients, 11.8 (95% confidence intervals 10.9-12.6) per 100 ICU admissions, were diagnosed with 752 episodes of severe sepsis. Site of infection was pulmonary in 50.3% of episodes and abdominal in 19.3% of episodes. The calculated incidence of severe sepsis in adults treated in Australian and New Zealand ICUs is 0.77 (0.76-0.79) per 1000 of population. 26.5% of patients with severe sepsis died in ICU, 32.4% died within 28 days of the diagnosis of severe sepsis and 37.5% died in hospital.

CONCLUSION

In this prospective study, 11.8 patients per 100 ICU admissions were diagnosed with severe sepsis and the calculated annual incidence of severe sepsis in adult patients treated in Australian and New Zealand ICUs is 0.77 per 1000 of population. This figure for the population incidence falls in the lower range of recent estimates from retrospective studies in the U.S. and the U.K.

The Clinical Value of the Systemic Inflammatory Response Syndrome (SIRS) in Abdominal Aortic Aneurysm Repair

OBJECTIVES

The systemic inflammatory response syndrome (SIRS) is common after major surgery. We examine the dynamics of SIRS in AAA patients, and assess the impact of the number of SIRS criteria on patient outcome.

DESIGN

Prospective study of 151 consecutive patients with AAA, undergoing repair electively, urgently or with rupture.

METHODS

SIRS scores and organ failure scores were recorded prospectively each day for all patients. Outcome measures included length of stay, evidence of organ failure and mortality.

RESULTS

The majority of patients developed SIRS postoperatively. Elective patients with a cumulative SIRS score of > or =10 during postoperative days 1-4 were more likely to die, compared to patients with a SIRS score of <10 (p=0.02). The development of SIRS late in the postoperative period (day 5-10) was associated with adverse outcome (death) in elective patients (p=0.01). The actual number of SIRS criteria present did not significantly correlate with either outcome or the incidence of organ failure.

CONCLUSIONS

SIRS is common in patients undergoing AAA repair. The SIRS score provides useful information regarding a patient's physiological state. High SIRS scores, and the development of SIRS late in the postoperative period are associated with adverse outcome in elective patients, and can therefore be used as an indicator of potential problems.

Quality of life of survivors from severe sepsis and septic shock may be similar to that of others who survive critical illness

Introduction

The objective of the present study was to compare the health-related quality of life (HR-QoL) of survivors from severe sepsis and septic shock with HR-QoL in others who survived critical illness not involving sepsis.

Methods

From March 1997 to March 2001, adult patients in an eight-bed medical/surgical intensive care unit (ICU) of a tertiary care hospital admitted with severe sepsis or septic shock (sepsis group; n = 305) were enrolled and compared with patients admitted without sepsis (control group; n = 392). Patients younger than 18 years (n = 48) and those whose ICU stay was 1 day or less (n = 453) were excluded. In addition, patients exhibiting nonsevere sepsis on admission were excluded (n = 87). Finally, patients who developed nonsevere sepsis or severe sepsis/septic shock after admission were also excluded (n = 88).

Results

In-hospital mortality rates were 34% in the sepsis group and 26% in the control group. There were no differences in sex, age, main activity (work status), and previous health state between groups. Survivors in the sepsis group had a significantly higher Acute Physiology and Chronic Health Evaluation II score on admission (17 versus 12) and stayed significantly longer in the ICU. A follow-up appointment was held 6 months after ICU discharge, and an EQ-5D (EuroQol five-dimension) questionnaire was administered. A total of 104 sepsis survivors and 133 survivors in the control group answered the EQ-5D questionnaire. Sepsis survivors reported significantly fewer problems only in the anxiety/depression dimension. Although there were no significant differences in the other dimensions of the EQ-5D, there was a trend towards fewer problems being reported by sepsis survivors.

Conclusion

Evaluation using the EQ-5D at 6 months after ICU discharge indicated that survivors from severe sepsis and septic shock have a similar HR-QoL to that of survivors from critical illness admitted without sepsis.

Relationship of pulmonary artery catheter use to mortality and resource utilization in patients with severe sepsis*

OBJECTIVE

To examine the relationship of pulmonary artery catheter (PAC) use to patient outcomes, including mortality rate and resource utilization, in patients with severe sepsis in eight academic medical centers.

DESIGN

Case-control, nested within a prospective cohort study.

SETTING

Eight academic tertiary care centers.

PATIENTS

Stratified random sample of 1,010 adult admissions with severe sepsis.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The main outcome measures were in-hospital mortality, total hospital charge, and length of stay (LOS) for patients with and without PAC use. The case-matched subset of patients included 141 pairs managed with and without the use of a PAC. The mortality rate was slightly but not statistically significantly lower among the PAC use group compared with those not using a PAC (41.1% vs. 46.8%, p =.34). Even this trend disappeared after we adjusted for the Charlson comorbidity score and sepsis-specific Acute Physiology and Chronic Health Evaluation (APACHE) III (adjusted odds ratio, 1.02; 95% confidence interval, 0.61-1.72). In linear regression models adjusted for the Charlson comorbidity score, sepsis-specific APACHE III, surgical status, receipt of a steroid before sepsis onset, presence of a Hickman catheter, and preonset LOS, no significant differences were found for total hospital charges (139,207 US dollars vs. 148,190, adjusted mean comparing PAC and non-PAC group, p =.57), postonset LOS (23.4 vs. 26.9 days, adjusted mean, p =.32), or total LOS in intensive care unit (18.2 vs. 18.8 days, adjusted mean, p =.82).

CONCLUSIONS

Among patients with severe sepsis, PAC placement was not associated with a change in mortality rate or resource utilization, although small nonsignificant trends toward lower resource utilization were present in the PAC group.

Infection Probability Score (IPS): A method to help assess the probability of infection in critically ill patients*

OBJECTIVE

To develop a simple score to help assess the presence or absence of infection in critically ill patients using routinely available variables.

DESIGN

Observational study of a prospective cohort of patients divided into a developmental set (n = 353) and a validation set (n = 140).

SETTING

Department of intensive care at an academic tertiary care center.

PATIENTS

Four hundred and ninety-three adult patients admitted to the intensive care unit for > or =24 hrs.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The presence of infection was defined using the Centers for Disease Control definitions. Body temperature, heart rate, respiratory rate, white blood cell count, and C-reactive protein concentrations were measured, and the Sequential Organ Failure Assessment score was calculated throughout the intensive care unit stay. Infection was documented in 92 of the 353 patients (26%) in the developmental set and in 41 of the 140 patients (29%) in the validation set. Univariate logistic regression was used to select significant predictors for infection. Each continuous predictor was transformed in a categorical variable using a robust locally weighted least square regression between infection and the continuous variable of interest. When more than two categories were created, the variable was separated into iso-weighted dummy variables. A multiple logistic regression model predicting infection was calculated with all the variables coded 1 or 0 allowing for relative scoring of the different predictors. The resulting Infection Probability Score consisted of six different variables and ranged from 0 to 26 points (0-2 for temperature, 0-12 for heart rate, 0-1 for respiratory rate, 0-3 for white blood cell count, 0-6 for C-reactive protein, 0-2 for Sequential Organ Failure Assessment score). The best predictors for infection were heart rate and C-reactive protein, whereas respiratory rate was found to have the poorest predictive value. The cutoff value for the Infection Probability Score was 14 points, with a positive predictive value of 53.6% and a negative predictive value of 89.5%. Model performance was very good (Hosmer-Lemeshow statistic, p =.918), and the areas under receiver operating characteristic curves were 0.820 for the developmental set and 0.873 for the validation set.

CONCLUSIONS

The Infection Probability Score is a simple score that can help assess the probability of infection in critically ill patients. The variables used are simple, routinely available, and familiar to clinicians. Patients with a score <14 points have only a 10% risk of infection.

Epidemiology of severe sepsis occurring in the first 24 hrs in intensive care units in England, Wales, and Northern Ireland

OBJECTIVE

To investigate the numbers, clinical characteristics, resource use, and outcomes of admissions who met precise clinical and physiologic criteria for severe sepsis (as defined in the PROWESS trial) in the first 24 hrs in the intensive care unit.

DESIGN

Observational cohort study, with retrospective analysis of prospectively collected data.

SETTING

Ninety-one adult general intensive care units in England, Wales, and Northern Ireland between 1995 and 2000.

PATIENTS

Patients were 56,673 adult admissions.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We found that 27.1% of adult intensive care unit admissions met severe sepsis criteria in the first 24 hrs in the intensive care unit. Most were nonsurgical (67%), and the most common organ system dysfunctions were seen in the cardiovascular (88%) and respiratory (81%) systems. Modeling the data for England and Wales for 1997 suggested that 51 (95% confidence interval, 46-58) per 100,000 population per year were admitted to intensive care units and met severe sepsis criteria in the first 24 hrs.Of the intensive care unit admissions who met severe sepsis criteria in the first 24 hrs, 35% died before intensive care unit discharge and 47% died during their hospital stay. Hospital mortality rate ranged from 17% in the 16-19 age group to 64% in those >85 yrs. In England and Wales in 1997, an estimated 24 (95% confidence interval, 21-28) per 100,000 population per year died after intensive care unit admissions with severe sepsis in the first 24 hrs. For intensive care unit admissions who met severe sepsis criteria in the first 24 hrs, median intensive care unit length of stay was 3.56 days (interquartile range, 1.50-9.32) and median hospital length of stay was 18 days (interquartile range, 8-36 days). These admissions used 45% of the intensive care unit and 33% of the hospital bed days used by all intensive care unit admissions.

CONCLUSIONS

Severe sepsis is common and presents a major challenge for clinicians, managers, and healthcare policymakers. Intensive care unit admissions meeting severe sepsis criteria have a high mortality rate and high resource use.

Influence of systemic inflammatory response syndrome and sepsis on outcome of critically ill infected patients

The clinical significance of the systemic inflammatory response in infected patients remains unclear. We examined risk factors for hospital mortality in 3,608 intensive care unit patients included in the European Sepsis Study. Patients were categorized as having infection without or with (i.e., sepsis) systemic inflammatory response, severe sepsis, and septic shock, on the first day of infection. Hospital mortality varied from 25 to 60% according to sepsis stage, but did not differ between the first two categories (hazard ratio, 0.94; p = 0.55), whereas there was a grading of severity from sepsis to severe sepsis (1.53, p < 10-4) and septic shock (2.64, p < 10-4). Within each stage, mortality was unaffected by the number of inflammatory response criteria. Prognostic factors identified by Cox regression included comorbid conditions, severity of acute illness and acute organ dysfunction, shock, nosocomial infection, and infection caused by aerobic gram-negative bacilli, enterobacteria, Staphylococcus aureus, and infection from a digestive or unknown source. We conclude that whereas the categorization of infection by the presence of organ dysfunction or shock has strong prognostic significance, infection and sepsis have similar outcomes, unaffected by the presence or number of inflammatory response criteria. Refinement of risk stratification of patients presenting with infection and no organ dysfunction is needed.

Severe sepsis: variation in resource and therapeutic modality use among academic centers

BACKGROUND

Treatment of severe sepsis is expensive, often encompassing a number of discretionary modalities. The objective of the present study was to assess intercenter variation in resource and therapeutic modality use in patients with severe sepsis.

METHODS

We conducted a prospective cohort study of 1028 adult admissions with severe sepsis from a stratified random sample of patients admitted to eight academic tertiary care centers. The main outcome measures were length of stay (LOS; total LOS and LOS after onset of severe sepsis) and total hospital charges.

RESULTS

The adjusted mean total hospital charges varied from 69 429 dollars to US237 898 dollars across centers, whereas the adjusted LOS after onset varied from 15.9 days to 24.2 days per admission. Treatments used frequently after the first onset of sepsis among patients with severe sepsis were pulmonary artery catheters (19.4%), ventilator support (21.8%), pressor support (45.8%) and albumin infusion (14.4%). Pulmonary artery catheter use, ventilator support and albumin infusion had moderate variation profiles, varying 3.2-fold to 4.9-fold, whereas the rate of pressor support varied only 1.92-fold across centers. Even after adjusting for age, sex, Charlson comorbidity score, discharge diagnosis-relative group weight, organ dysfunction and service at onset, the odds for using these therapeutic modalities still varied significantly across centers. Failure to start antibiotics within 24 hours was strongly correlated with a higher probability of 28-day mortality (r2 = 0.72).

CONCLUSION

These data demonstrate moderate but significant variation in resource use and use of technologies in treatment of severe sepsis among academic centers. Delay in antibiotic therapy was associated with worse outcome at the center level.

The epidemiology of sepsis in the United States from 1979 through 2000

BACKGROUND

Sepsis represents a substantial health care burden, and there is limited epidemiologic information about the demography of sepsis or about the temporal changes in its incidence and outcome. We investigated the epidemiology of sepsis in the United States, with specific examination of race and sex, causative organisms, the disposition of patients, and the incidence and outcome.

METHODS

We analyzed the occurrence of sepsis from 1979 through 2000 using a nationally representative sample of all nonfederal acute care hospitals in the United States. Data on new cases were obtained from hospital discharge records coded according to the International Classification of Diseases, Ninth Revision, Clinical Modification.

RESULTS

Review of discharge data on approximately 750 million hospitalizations in the United States over the 22-year period identified 10,319,418 cases of sepsis. Sepsis was more common among men than among women (mean annual relative risk, 1.28 [95 percent confidence interval, 1.24 to 1.32]) and among nonwhite persons than among white persons (mean annual relative risk, 1.90 [95 percent confidence interval, 1.81 to 2.00]). Between 1979 and 2000, there was an annualized increase in the incidence of sepsis of 8.7 percent, from about 164,000 cases (82.7 per 100,000 population) to nearly 660,000 cases (240.4 per 100,000 population). The rate of sepsis due to fungal organisms increased by 207 percent, with gram-positive bacteria becoming the predominant pathogens after 1987. The total in-hospital mortality rate fell from 27.8 percent during the period from 1979 through 1984 to 17.9 percent during the period from 1995 through 2000, yet the total number of deaths continued to increase. Mortality was highest among black men. Organ failure contributed cumulatively to mortality, with temporal improvements in survival among patients with fewer than three failing organs. The average length of the hospital stay decreased, and the rate of discharge to nonacute care medical facilities increased.

CONCLUSIONS

The incidence of sepsis and the number of sepsis-related deaths are increasing, although the overall mortality rate among patients with sepsis is declining. There are also disparities among races and between men and women in the incidence of sepsis. Gram-positive bacteria and fungal organisms are increasingly common causes of sepsis.

The systemic inflammatory response syndrome, organ failure, and mortality after abdominal aortic aneurysm repair

BACKGROUND

Organ failure is a major cause of morbidity and mortality after abdominal aortic aneurysm (AAA) repair. The aim of this study was to determine the relationships between the systemic inflammatory response syndrome (SIRS), organ failure, and mortality after AAA repair and to determine whether the clinical monitoring of SIRS was a useful adjunct to clinical method.

METHODS

One hundred consecutive patients undergoing open AAA repair were prospectively studied. Patients were divided into three groups: those undergoing elective AAA repair, those with symptomatic but nonruptured AAA, and those with ruptured AAA. The presence of SIRS and organ failure was recorded on a daily basis for each patient until discharge or death.

RESULTS

Most patients had SIRS develop during the postoperative period: 89% of the elective group, 92% of the emergency nonruptured (urgent) group, and 100% of the ruptured group. Multiorgan failure occurred in 3.8% of the elective group, 38% of the urgent group, and 64% of the ruptured AAA group. After ruptured AAA repair, the concurrent absence of both SIRS and any organ failure for 48 hours had a sensitivity of 93% and a specificity of 91% as a predictive indicator of subsequent survival to hospital discharge. Patients in whom multiorgan failure developed after ruptured AAA repair had a significantly higher mortality rate (69%) than those who did not (0%; P =.001; 95% CI for the difference, 30.2% to 85.8%).

CONCLUSION

The differences in the incidence rate of multiorgan failure between the patient groups compared with the high incidence rate of SIRS in all patient groups supports the two-hit hypothesis of multiorgan failure. The presence of multiorgan failure after ruptured AAA repair is associated with poor outcome. The absence of SIRS and organ failure in these patients is a good predictive indicator of survival.

Usefulness of procalcitonin for diagnosis of sepsis in the intensive care unit

INTRODUCTION

The diagnosis of sepsis in critically ill patients is challenging because traditional markers of infection are often misleading. The present study was conducted to determine the procalcitonin level at early diagnosis (and differentiation) in patients with systemic inflammatory response syndrome (SIRS) and sepsis, in comparison with C-reactive protein, IL-2, IL-6, IL-8 and tumour necrosis factor-alpha.

METHOD

Thirty-three intensive care unit patients were diagnosed with SIRS, sepsis or septic shock, in accordance with the American College of Chest Physicians/Society of Critical Care Medicine consensus criteria. Blood samples were taken at the first and second day of hospitalization, and on the day of discharge or on the day of death. For multiple group comparisons one-way analysis of variance was applied, with post hoc comparison. Sensitivity, specificity and predictive values of PCT and each cytokine studied were calculated.

RESULTS

PCT, IL-2 and IL-8 levels increased in parallel with the severity of the clinical condition of the patient. PCT exhibited a greatest sensitivity (85%) and specificity (91%) in differentiating patients with SIRS from those with sepsis. With respect to positive and negative predictive values, PCT markedly exceeded other variables.

DISCUSSION

In the present study PCT was found to be a more accurate diagnostic parameter for differentiating SIRS and sepsis, and therefore daily determinations of PCT may be helpful in the follow up of critically ill patients.

Resource utilization among patients with sepsis syndrome

OBJECTIVE

To assess the resource utilization associated with sepsis syndrome in academic medical centers.

DESIGN

Prospective cohort study.

SETTING

Eight academic, tertiary-care centers.

PATIENTS

Stratified random sample of 1,028 adult admissions with sepsis syndrome and all 248,761 other adult admissions between January 1993 and April 1994. The main outcome measures were length of stay (LOS) in total and after onset of sepsis syndrome (post-onset LOS) and total hospital charges.

RESULTS

The mean LOS for patients with sepsis was 27.7 +/- 0.9 days (median, 20 days), with sepsis onset occurring after a mean of 8.1 +/- 0.4 days (median, 3 days). For all patients without sepsis, the LOS was 7.2 +/- 0.03 days (median, 4 days). In multiple linear regression models, the mean for patients with sepsis syndrome was 18.2 days, which was 11.0 days longer than the mean for all other patients (P < .0001), whereas the mean difference in total charges was $43,000 (both P < .0001). These differences were greater for patients with nosocomial as compared with community-acquired sepsis, although the groups were similar after adjusting for pre-onset LOS. Eight independent correlates of increased post-onset LOS and 12 correlates of total charges were identified.

CONCLUSIONS

These data quantify the resource utilization associated with sepsis syndrome, and demonstrate that resource utilization is high in this group. Additional investigation is required to determine how much of the excess post-onset LOS and charges are attributable to sepsis syndrome rather than the underlying medical conditions.

Air embolism as a cause of the systemic inflammatory response syndrome: a case report

We describe a case of systemic inflammatory response syndrome associated with air embolism following the removal of a central line catheter, coupled with a deep inspiratory maneuver. The presence of a patent foramen ovale allowed the passage of a clinically significant amount of air from the venous circulation to the systemic circulation. The interaction of air with the systemic arterial endothelium may have triggered the release of endothelium-derived cytokines, resulting in the physiologic response of systemic inflammatory response syndrome.

An economic evaluation of activated protein C treatment for severe sepsis

BACKGROUND

Recombinant human activated protein C was shown in the Recombinant Human Activated Protein C Worldwide Evaluation in Severe Sepsis (PROWESS) study to reduce mortality among patients with severe sepsis. A post hoc reanalysis by the Food and Drug Administration (FDA) of data from this study suggested that the reduction in mortality was restricted to patients with Acute Physiology and Chronic Health Evaluation (APACHE II) scores of 25 or more.

METHODS

We estimated the cost effectiveness of activated protein C as compared with conventional care for patients with severe sepsis. We performed an economic analysis involving all patients, as well as analyses of subgroups defined according to age and severity of illness. The probabilities of transition between clinical states and the estimates of resource use were derived from a population-based cohort of patients with severe sepsis. We used data on the effectiveness of activated protein C from the PROWESS study and analyses by the FDA.

RESULTS

The cost per life-year gained by treating all patients with activated protein C was $27,936. It was more cost effective to treat patients with an APACHE II score of 25 or more ($24,484 per life-year gained) than those with a lower APACHE II score ($35,632 per life-year gained). The cost effectiveness of treating patients with an APACHE II score of 24 or less increased to $575,054 per life-year gained when the FDA's estimates of effectiveness were considered. For patients with an APACHE II score of 25 or more, the cost per life-year gained increased with age ($16,309 for patients less than 40 years of age; $28,100 for those 80 years of age or older).

CONCLUSIONS

Activated protein C is relatively cost effective when targeted to patients with severe sepsis, greater severity of illness (an APACHE II score of 25 or more), and a reasonable life expectancy if they survive the episode of sepsis. Further research is needed to determine the cost effectiveness of activated protein C for patients with sepsis and less severe illness.

Prediction of shock in febrile medical patients with a clinical infection

OBJECTIVE

Shock in the course of fever is likely caused by septic shock. Because septic shock carries a high mortality rate, early recognition could benefit the patient. We tried to predict the development of shock in medical patients with fever and a clinical infection, on the basis of clinical and microbiological information, and to evaluate the role therein of systemic inflammatory response syndrome (SIRS) criteria: abnormal body temperature, tachycardia, tachypnea, and abnormal white blood cell counts.

DESIGN

Prospective observational study.

SETTING

Department of Internal Medicine at a university hospital.

PATIENTS

Patients were 212 consecutive medical patients with newly onset fever (temperature, >38.0 degrees C axillary or >38.3 degrees C rectally) and a clinical source of infection.

MEASUREMENTS AND MAIN RESULTS

Of the 212 patients enrolled, 14 developed shock (i.e., a decrease in systolic arterial blood pressure of >40 mm Hg) during a maximum follow-up period of 7 days after inclusion. In univariate analyses, advanced age, prior urogenital disease, an abdominal source, nosocomial infections, and bacteremia predisposed patients to shock (p < .05). For clinical variables, obtained daily for 2 days after inclusion, a low performance (p < .001), the peak respiratory rate (p < .05), the peak heart rate (p < .05), the nadir score on the Glasgow Coma Scale (p < .005), the peak and nadir white blood cell counts (p < .005), and the nadir albumin (p < .01) and peak creatinine concentrations in blood (p < .001) predicted shock development. In multivariate analysis, the presence of bacteremia, the peak respiratory rate, the nadir Glasgow Coma Scale score, and the peak white blood cell count positively and the peak erythrocyte sedimentation rate negatively contributed to prediction of shock development. In contrast, SIRS had less predictive value, mainly because of lack of predictive value of peak heart rate and temperature in multivariate models.

CONCLUSION

In febrile medical patients with a clinical infection, the development of shock involves an interaction between circulating microbial products and the host response, which can be recognized clinically by variables easily obtained at the bedside and partly different from the set used to define SIRS.

Long-term health-related quality of life in survivors of sepsis. Short Form 36: a valid and reliable measure of health-related quality of life

OBJECTIVE

To describe the long-term health-related quality of life (HRQL) of survivors of sepsis and to evaluate the reliability and validity of the medical outcomes study Short Form-36 (SF-36) in this population.

STUDY DESIGN

Cross-sectional survey.

SETTING

University intensive care unit.

PATIENTS

Surviving patients over the age of 17 yrs who met the criteria for the Society of Critical Care Medicine/American College of Chest Physicians definition of sepsis identified through a review of patients admitted to the intensive care unit from 1994 to 1998.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Baseline demographics and clinical characteristics were abstracted from the medical chart. After hospital discharge, the SF-36 and Patrick's Perceived Quality of Life scale were administered by telephone. The SF-36 was readministered 2 wks later. We screened the charts of 109 patients; 78 had a diagnosis of sepsis. Of these, 31 had died, 3 had severe communication problems, 9 refused to participate, and 5 patients could not be located. A total of 30 patients completed the first interview; 26 completed the second. Compared with established norms for the U.S. general population, survivors of sepsis scored significantly lower on the physical functioning, role physical, general health, vitality, and social functioning domains, as well as on the Physical Health Summary Scale. Mean scores on the Mental Health Summary Scale were very similar between the survivors of sepsis and U.S. norms. The SF-36 demonstrated high internal consistency (Cronbach's alpha ranged from 0.65 to 0.94) and excellent test-retest stability (intraclass correlation coefficient ranged from 0.75 to 0.97). Both the Physical Health Summary Scale and the Mental Health Summary Scale correlated well with overall Perceived Quality of Life scores (Pearson correlation coefficients 0.45 and 0.56, respectively).

CONCLUSIONS

The long-term HRQL of survivors of sepsis is significantly lower than that of the general U.S. population. The SF-36 demonstrated good reliability and validity when used to measure HRQL in survivors of sepsis.

Systemic inflammatory response syndrome score at admission independently predicts mortality and length of stay in trauma patients

BACKGROUND

Recent studies have documented that the systemic inflammatory response syndrome (SIRS) score is a useful predictor of outcome in critical surgical illness. The duration and severity of SIRS are associated with posttrauma multiple organ dysfunction and mortality. We sought to determine whether the severity of SIRS at admission is an accurate predictor of mortality and length of stay (LOS) in trauma patients.

METHODS

Prospective data of 4,887 trauma admissions to a Level I trauma center over a 18-month period (January 1997 to July 1998) were analyzed. Patients were stratified by age and Injury Severity Score (ISS), and a SIRS severity score (1 to 4) was calculated at admission (1 point for each component present: fever or hypothermia, tachypnea, tachycardia, and leukocytosis). The SIRS score was evaluated as an independent predictor of mortality and LOS by chi2 and multivariate logistic regression.

RESULTS

Trauma patients (n = 4,887, 83% blunt injuries, 72% male) had the following characteristics: 73.1% were age 18 to 45 years, 17.5% were age 46 to 65 years, and 9.4% were age > or =66 years; 77.7% had ISS less than 15, 18.8% had ISS 16 to 29, and 3.5% had ISS greater than 29. Analysis of variance adjusting for age and ISS determined that SIRS score of 2 was a significant predictor of LOS. Furthermore, the relative risk of death increased significantly with SIRS score of 2 when age and ISS were held constant.

CONCLUSION

Logistic regression analysis confirmed that a SIRS score of 2 was a significant independent predictor of increased mortality and LOS in trauma patients. These data suggest that admission SIRS scoring in trauma patients is a simple tool that may be used as a predictor of outcome and resource utilization.

Epidemiological differences between sepsis syndrome with bacteremia and culture-negative sepsis

OBJECTIVE

To explore the association of putative disease markers and potential risk factors with the nosocomial sepsis syndrome.

DESIGN

Prospective case-control study matched for gender, age, and length of preinfection hospital stay.

SETTING

1,200-bed tertiary-care center in Spain.

PATIENTS

Cases were selected using the sepsis syndrome criteria of the American College of Chest Physicians/Society of Critical Care Medicine Consensus Conference and were divided into three groups: sepsis with bacteremia (109 cases), sepsis with positive culture other than blood (122 cases), and sepsis with negative culture (115 cases without documented infection but with sepsis syndrome, clinically suspected infection, and empirical antibiotic treatment). Controls were randomly selected from the daily list of inpatients. Data were collected prospectively. Crude and multiple-risk-factor-adjusted odds ratios and their 95% confidence intervals were computed using conditional logistic regression analysis.

RESULTS

Presence of coma in the 48 hours before sepsis, intensive care unit (ICU) stay, and decreased serum albumin levels at admission were common epidemiological markers identified for the three groups of cases. Having a central venous catheter was the main healthcare-related risk factor for bacteremia. ICU stay and nasogastric tube were the main risk factors for sepsis with positive culture other than blood. Coma within 48 hours before sepsis and the need of intensive care were the only two markers identified for culture-negative sepsis.

CONCLUSION

Culture-negative sepsis does not behave like culture-positive sepsis, and this may imply that implementation of preventive measures to decrease the risk of bacteremia may not decrease the risk of sepsis syndrome.

Plasma granulocyte colony-stimulating factor and granulocyte-macrophage colony-stimulating factor levels in critical illness including sepsis and septic shock: relation to disease severity, multiple organ dysfunction, and mortality

OBJECTIVE

To define the circulating levels of granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor (GM-CSF) during critical illness and to determine their relationship to the severity of illness as measured by the Acute Physiology and Chronic Health Evaluation (APACHE) II score, the development of multiple organ dysfunction, or mortality.

DESIGN

Prospective cohort study.

SETTING

University hospital intensive care unit.

PATIENTS

A total of 82 critically ill adult patients in four clinically defined groups, namely septic shock (n = 29), sepsis without shock (n = 17), shock without sepsis (n = 22), and nonseptic, nonshock controls (n = 14).

INTERVENTIONS

None.

MEASUREMENT AND MAIN RESULTS

During day 1 of septic shock, peak plasma levels of G-CSF, interleukin (IL)-6, and leukemia inhibitory factor (LIF), but not GM-CSF, were greater than in sepsis or shock alone (p < .001), and were correlated among themselves (rs = 0.44-0.77; p < .02) and with the APACHE II score (rs = 0.25-0.40; p = .03 to .18). G-CSF, IL-6, and UF, and sepsis, shock, septic shock, and APACHE II scores were strongly associated with organ dysfunction or 5-day mortality by univariate analysis. However, multiple logistic regression analysis showed that only septic shock remained significantly associated with organ dysfunction and only APACHE II scores and shock with 5-day mortality. Similarly, peak G-CSF, IL-6, and LIF were poorly predictive of 30-day mortality.

CONCLUSIONS

Plasma levels of G-CSF, IL-6, and LIF are greatly elevated in critical illness, including septic shock, and are correlated with one another and with the severity of illness. However, they are not independently predictive of mortality, or the development of multiple organ dysfunction. GM-CSF was rarely elevated, suggesting different roles for G-CSF and GM-CSF in human septic shock.

Continuous plasmafiltration in sepsis syndrome. Plasmafiltration in Sepsis Study Group

OBJECTIVE

To assess the effect of plasmafiltration (PF) on biochemical markers of inflammation, cytokines, organ dysfunction, and 14-day mortality in human sepsis.

DESIGN

Multicenter, prospective, randomized, controlled clinical trial.

SETTING

Seven university-affiliated intensive care units.

PATIENTS

Thirty patients (22 adults, eight children) with new (<24 hrs) clinical evidence of infection and sepsis syndrome were enrolled. Fourteen of 30 (nine adults, five children) were randomized to PF.

INTERVENTIONS

All patients received protocol-driven supportive intensive care, and those randomized to PF received continuous plasma exchange for 34 hrs using a hollow-fiber plasma filter.

MEASUREMENTS AND MAIN RESULTS

Illness severity and risk of death were calculated with the Pediatric Risk of Mortality (children) and the Acute Physiology and Chronic Health Evaluation II (adults) scales. Plasma samples (0, 6, 24, and 48 hrs) were assayed for acute-phase proteins (albumin, globulin, C-reactive protein, alpha1-antitrypsin, haptoglobin), inflammatory mediators (complement fragment C3, thromboxane B2), and cytokines (interleukin-6, granulocyte colony-stimulating factor, leukemia inhibitory factor). Sieving coefficients were estimated from filtrate concentrations at 3 hrs. The two groups were matched for incidence of septic shock (13 of 14 vs. 11 of 16), refractory shock (three of 14 vs. six of 16), bacteremia (six of 14 vs. five of 16), severity of illness, and calculated risk of death (0.68 vs. 0.64). There was no difference in mortality. Eight of 14 PF patients (57%) and eight of 16 controls (50%) survived for 14 days (p = .73, Fisher's exact test). Multiple logistic regression revealed age (odds ratio, 16.4:1; 95% confidence interval, 2.12-infinity) and shock (10.6:1; 1.32-infinity) as significant predictors of death; plasmafiltration was associated with a nonsignificant reduction in the risk of death (odds ratio, 1.78:1; 95% confidence interval, 0.20-18.1). The mean (SD) number of organs failing in the first 7 days in the PF group was 2.57 (0.94) vs. 2.94 (0.85) in controls (p = .37, Mann-Whitney U test). Both groups had similarly elevated plasma concentrations of all inflammatory mediators except complement fragment C3 at study entry. Leukemia inhibitory factor was detectable in four patients only. PF did not influence mean concentrations of interleukin-6, granulocyte colony-stimulating factor, thromboxane B2, total white cell count, neutrophil count, or platelet count, but it was associated with significant reductions of alpha1-antitrypsin, haptoglobin, C-reactive protein, and complement fragment C3 in the first 6 hrs (p < .05). The sieving coefficients for all inflammatory mediators approached unity.

CONCLUSIONS

PF caused a significant attenuation of the acute-phase response in sepsis. There was no significant difference in mortality, but there was a trend toward fewer organs failing in the PF group that suggests that this procedure might be beneficial.

Evaluation of oxygen consumption and resting energy expenditure in critically ill patients with systemic inflammatory response syndrome

OBJECTIVE

To determine whether oxygen consumption VO2), CO2 production, and resting energy expenditure (REE) in critically ill patients differ in varying grades of systemic inflammatory response syndrome (SIRS).

DESIGN

Prospective, clinical study.

SETTING

Intensive care unit at a university hospital.

PATIENTS

Twenty-six critically ill patients requiring mechanical ventilation.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

A total of 100 metabolic measurements were performed. The grade of SIRS and the Acute Physiology and Chronic Health Evaluation II score were evaluated at the time of the metabolic cart study. VO2 and REE differed among the groups inadequate for SIRS (non-SIRS), with SIRS without infection (nonseptic SIRS), and with SIRS with infection (septic SIRS) (125 +/- 37 mL/min/m2 and 855 +/- 204 kcal/day/m2, 135 +/- 33 mL/min/m2 and 948 +/- 214 kcal/day/m2, and 166 +/- 55 mL/min/m2 and 1149 +/- 339 kcal/day/m2, respectively; p < .005). Patients with septic SIRS had higher VO2 and REE than patients with non-SIRS and nonseptic SIRS.

CONCLUSION

VO2 and REE differ among groups of patients with non-SIRS, nonseptic SIRS, and septic SIRS. Patients with septic SIRS have higher VO2 and REE than patients with non-SIRS or nonseptic SIRS. The present study shows that classifying patients into three grades (non-SIRS, nonseptic SIRS, and septic SIRS) is a valid predictor of metabolic stress in critically ill patients.

The clinical host response to microbial infection in medical patients with fever

STUDY OBJECTIVES

Predictors among demographic, clinical, and laboratory variables for a microbial (nonviral/nonchlamydial) infection in hospitalized medical patients with new onset of fever (temperature > or =38.0 degrees C axillary or > or =38.3 degrees C rectal) were analyzed and compared with the criteria for the systemic inflammatory response syndrome (SIRS), including an abnormal body temperature and WBC count, tachypnea and tachycardia, and sepsis, defined as SIRS and the presence of a clinical infection.

DESIGN

A prospective cohort study.

SETTING

Department of internal medicine at a university hospital.

PATIENTS

In 300 hospitalized medical patients with new onset of fever, demographic, clinical, and laboratory variables were obtained during the first 2 days after inclusion, and peak and nadir values, when appropriate, were taken. Microbiologic results for 7 days were collected. Clinical information was used to decide on the presence of a clinical infection.

MEASUREMENTS AND RESULTS

One hundred thirty-three of 300 patients (44%) had a microbial infection: 26% suffered from local microbial infection only, 9% from bacteremia only, and 9% had bloodstream plus local microbial infections. Patients with a microbial infection had a higher World Health Organization performance score at home (p<0.05), higher peak body temperature (p<0.001), higher nadir and peak WBC counts (p<0.05), lower nadir platelet count (p<0.01), higher peak alanine and aspartate aminotransferases (p<0.01), and lower nadir albumin (p<0.001) levels in blood during the first 2 days after inclusion than those without infection. Using multivariate techniques, predictors for microbial infection or bacteremia alone, independent of age, sex, underlying disease, and clinical infection, were peak temperature, peak WBC count, and nadir platelet count and albumin level. In contrast, conventional SIRS/sepsis definitions and criteria predicted microbial infection less well, mainly because tachypnea and tachycardia were of no predictive value.

CONCLUSIONS

In febrile medical patients, microbial infection can be predicted with use of easily obtained clinical and laboratory variables, including peak temperature, peak WBC count, and nadir platelet count and albumin level within the first 2 days. The new model predicted microbial infection better than conventional SIRS/sepsis criteria. This may help to improve the clinical recognition of the systemic host response to microbial infection and to refine SIRS/sepsis definitions.

Low systemic vascular resistance state in patients undergoing cardiopulmonary bypass

OBJECTIVE

To determine the prevalence, hemodynamic characteristics, and risk factors for the low systemic vascular resistance (SVR) state in patients who have undergone cardiopulmonary bypass.

DESIGN

Prospective cohort study.

SETTING

The intensive care unit of a tertiary care hospital.

PATIENTS

Seventy-nine consecutive patients who underwent coronary artery bypass graft, mitral valve, or aortic valve procedures.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Low SVR was defined as an indexed systemic vascular resistance (SVRi) of <1800 dyne x sec/cm5 x m2 at two consecutive times postoperatively. SVRi, cardiac index, mean arterial pressure, temperature, and central venous pressure were recorded before bypass and at 0, 1, 2, 4, 8, and 16 hrs after bypass. We recorded age, gender, urgency of operation, use of angiotensin-converting enzyme inhibitors and calcium channel blockers, ejection fraction, pump time, cross-clamp time, use of antifibrinolytics, type of oxygenator, amrinone use, postoperative biochemical and hematologic values, medication use, fluid balance, intensive care unit admission duration, and hospital admission duration. We assessed the role of diabetes mellitus, current smoking, and systemic hypertension. The incidence of the low-SVR state was 35 of 79 patients during a 3-month period (44%). At 8 hrs postoperatively, the SVRi in low-SVR and non-low-SVR patients was 1594+/-50 (SEM) and 2103+/-56 (SEM) dyne x sec/cm5 x m2, respectively (p < .001). In low-SVR patients, there was an initial and sustained increase in cardiac index and central venous pressure that preceded the decrease in mean arterial pressure. The decrease in mean arterial pressure was maximal at 8 hrs postoperatively. Patients with low SVR were more likely to have longer cross-clamp times, to be male, and to have lower postoperative platelet counts (p < .05 for all). Low-SVR patients were less likely to require dobutamine in the first 4 hrs postoperatively.

CONCLUSIONS

Low SVR, a probable manifestation of systemic inflammatory response syndrome, is common in patients after cardiopulmonary bypass. These patients may respond better to a vasopressor to restore vascular tone than to volume loading to further increase cardiac index.

The epidemiology of bacterial sepsis

As a result of better understanding of pathogenesis, new definitions of sepsis have been proposed, and the complexity of this syndrome is clearer. Population-based studies of bloodstream infections--what now is called sepsis--have helped us to understand the natural history of this very frequent problem. The mortality and morbidity of each of the systemic inflammatory response syndrome stages have been described; our ability to better understand and predict these stages will help us to make better therapeutic decisions.

Determinants of hospital mortality after coronary artery bypass grafting

OBJECTIVES

To examine causes of death and to find predictors of hospital mortality after elective coronary artery bypass graft (CABG) surgery.

DESIGN

Case-control study.

SETTING

Tertiary teaching hospital.

METHODS

We prospectively collected various preoperative, operative, and immediate postoperative variables in a cohort of patients undergoing elective CABG surgery.

RESULTS

Of the 2,014 consecutive patients (mean [+/- SD] age of 61.3+/-6.7 years old) undergoing elective CABG over a 2-year period, 27 patients (1.3%) died during their hospitalization. The main causes of death (either isolated or in combination) were cardiogenic shock (n = 13), brain death or stroke (n = 7), septic shock (n = 4), ARDS (n = 2), and pulmonary embolism (n = 1). A univariate statistical analysis revealed factors that significantly correlate with outcome: patient age, preoperative left ventricular ejection fraction, bypass time, aortic cross-clamp time, number of blood units transfused, number of inotropic agents administered in the operating room during the first postoperative day (POD), history of arterial hypertension, intra-aortic balloon pump usage, and perioperative development of shock. A logistic regression analysis showed that the combination of the number of inotropes and the number of blood units administered in the operating room during POD 1 was the most important determinant of outcome, with an overall positive predictive value of 91.7%.

CONCLUSIONS

We conclude that the analysis of simple variables enhances our ability to accurately predict hospital mortality in patients undergoing elective CABG surgery. The number of inotropic agents and blood transfusions administered during the immediate postoperative period is the most important independent predictor of hospital mortality.

Prediction of mortality in febrile medical patients: How useful are systemic inflammatory response syndrome and sepsis criteria?

STUDY OBJECTIVES

The aim was to evaluate demographic, clinical, and laboratory variables in febrile patients, with or without a microbiologically confirmed infection, for prediction of death, in comparison to the systemic inflammatory response syndrome (SIRS) and its criteria, such as abnormal temperature, tachycardia, tachypnea, and abnormal WBC count, and to sepsis, that includes SIRS and an infection.

DESIGN

A prospective cohort study.

SETTING

Department of internal medicine at a university hospital.

PATIENTS

In 300 consecutive, hospitalized medical patients with new onset of fever, demographic, clinical, and laboratory variables were obtained during the 2 days after inclusion, while microbiological results for a follow-up period of 7 days were collected. Patients were followed up for survival or death, up to a maximum of 28 days after inclusion.

MEASUREMENTS AND RESULTS

Of all patients, 95% had SIRS, 44% had sepsis with a microbiologically confirmed infection, and 9% died. A model with a set of variables all significantly (p<0.01) contributing to the prediction of mortality was derived. The set included the presence of hospital-acquired fever, the peak respiratory rate, the nadir score on the Glasgow coma scale, and the nadir albumin plasma level within the first 2 days after inclusion. This set of variables predicted mortality for febrile patients with microbiologically confirmed infection even better. The predictive values for mortality of SIRS and sepsis were less than that of our set of variables.

CONCLUSIONS

In comparison to SIRS and sepsis, the new set of variables predicted mortality better for all patients with fever and also for those with microbiologically confirmed infection only. This type of effort may help in refining definitions of SIRS and sepsis, based on prognostically important demographic, clinical, and laboratory variables that are easily obtainable at the bedside.

Procalcitonin and C-reactive protein during the early posttraumatic systemic inflammatory response syndrome

OBJECTIVES

To describe the initial evolution of serum procalcitonin (PCT) and C-reactive protein (CRP) in previously healthy adult trauma patients and to compare the relationship of the expression of these two proteins with indicators of trauma severity.

DESIGN

Prospective, descriptive, longitudinal study.

SETTING

Surgical ICU in an university hospital.

PATIENTS

Twenty-one patients admitted during the first posttraumatic 3 h exhibiting an Injury Severity Score (ISS) between 16 and 50 were enrolled.

MEASUREMENTS

Blood sampling was performed on admission and on posttraumatic days 0.5, 1, 2 and 3 to assess serum levels of PCT and CRP. Total creatine kinase (CKtot) and lactate dehydrogenase (LDHtot) activities in the serum were used as tissue damage indicators.

RESULTS

PCT exhibited an early and transient increase in serum levels similar to a more delayed change of CRP levels. Peak PCT and peak CRP were related to the ISS, the extent of tissue damage and the amount of fluid replacement during the first day. During the first 3 posttraumatic days, 90% of the patients exhibited a generalized inflammatory syndrome without infection.

CONCLUSIONS

An early and transient release of PCT into the circulation was observed after severe trauma and the amount of circulating PCT seemed proportional to the severity of tissue injury and hypovolemia, yet unrelated to infection. The predictive value of both PCT and CRP for a forthcoming multiple organ failure still remains to be clarified.

Systemic inflammatory response syndrome and organ dysfunction following gastrointestinal surgery

OBJECTIVES

Progression from systemic inflammatory response syndrome (SIRS) to sepsis, severe sepsis, and septic shock has been demonstrated in a variety of patients. However, the presence of SIRS alone was not helpful in predicting the development of multiple organ dysfunction syndrome (MODS) since SIRS includes many nonprogressive conditions. This study was conducted to investigate the clinical significance of SIRS in postoperative patients.

DESIGN

Retrospective study.

SETTING

The surgical department of a university hospital.

PATIENTS

Two hundred ninety-two consecutive patients who received elective common gastrointestinal surgery (esophagectomy, pancreatoduodenectomy, hepatectomy, gastrectomy, colorectal resection, and laparoscopic cholecystectomy) between 1992 and 1995.

INTERVENTIONS

Patients were analyzed for preoperative physiologic status, surgical stress parameters, and postoperative status of SIRS, complications, and end-organ dysfunction.

MEASUREMENTS AND MAIN RESULTS

Duration of SIRS or positive criteria's number of SIRS after surgery significantly correlated with surgical stress parameters (blood loss/body weight and operation time) and peak serum C-reactive protein concentrations. SIRS that continued or reappeared after postoperative day 3 was an early sign of postoperative complications. SIRS continuing consecutively for 2 days after postoperative day 3 had a 70.6% positive predictive value and a 92.5% negative predictive value for postoperative complications. Septic complications and prolongation of SIRS were associated with MODS. Five of six patients who met the SIRS criteria for >30 days developed severe MODS, and three of them died.

CONCLUSIONS

SIRS is a useful criterion for the recognition of postoperative complications and end-organ dysfunctions. Early recovery from SIRS may arrest the progression of organ dysfunction.

Participation of tissue factor and thrombin in posttraumatic systemic inflammatory syndrome

OBJECTIVE

To determine the roles of tissue factor and thrombin on the systemic inflammatory response syndrome (SIRS) in posttrauma patients, as well as to investigate the relationship between SIRS and sepsis.

DESIGN

Prospective, cohort study.

SETTING

General intensive care unit of a tertiary care emergency department.

PATIENTS

Forty trauma patients were classified into subgroups, according to the duration of SIRS: non-SIRS patients (n = 9); patients with SIRS for < 2 days (n = 15); and patients with SIRS for > 3 days (n = 16).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Tissue factor antigen concentration, prothrombin fragment F1+2, thrombin antithrombin complex, fibrinopeptide A, and cross-linked fibrin degradation products (D-dimer) were measured on the day of admission, and on days 1 through 4 after admission. Simultaneously, the number of SIRS criteria that the patients met and the disseminated intravascular coagulation score were determined. The results of these measurements, frequency of acute respiratory distress syndrome (ARDS), multiple organ dysfunction syndrome, sepsis, and outcome were compared among the groups. The values of all five hemostatic molecular markers in the patients with SIRS for > 3 days were significantly more increased than those molecular marker values measured in the other groups on the day of admission. These values continued to be markedly high up to day 4 of admission. The occurrence rates of disseminated intravascular coagulation in these patient groups were significantly higher than those rates in the other two groups (p = .0001), and the disseminated intravascular coagulation scores did not improve during the study period. The occurrence rates of ARDS (p < .05) and multiple organ dysfunction syndrome (p < .01) were higher in patients with SIRS for > 3 days compared with those rates in the other groups, and the patients with SIRS for > 3 days had a poor outcome. No significant difference was noted in the frequency of sepsis among the groups.

CONCLUSIONS

Sustained SIRS is the main determinant for ARDS, multiple organ dysfunction syndrome, and outcome in posttrauma patients. Disseminated intravascular coagulation associated with massive thrombin generation and its activation is involved in the pathogenesis of sustained SIRS. Sepsis has a small role in early posttrauma multiple organ dysfunction syndrome.

American College of Chest Physicians/Society of Critical Care Medicine Consensus Conference definitions of the systemic inflammatory response syndrome and allied disorders in relation to critically injured patients

OBJECTIVES

To determine the frequency of the proposed definitions for the systemic inflammatory response syndrome (SIRS), sepsis and septic shock, and to further define severe SIRS and sterile shock as determined at 24 hrs of admission to an intensive care unit (ICU) in critically ill trauma patients without head injury, and their relationships to mechanism of injury, Acute Physiology and Chronic Health Evaluation (APACHE) II score, risk of death, Injury Severity Score (ISS), number of organ failures, and mortality rate.

DESIGN

Prospective, inception cohort analysis.

SETTING

Sixteen-bed surgical ICU in a teaching hospital.

PATIENTS

Four hundred fifty critically injured patients without associated head trauma. Penetrating trauma accounted for 70% (gunshot 202; stab 113) and nonpenetrating trauma for 30% (motor vehicle collision 103; blunt 32) of admissions. Three hundred ninety-four (88%) patients underwent surgical procedures.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Infective and noninfective insults were distinguished by the need for therapeutic or prophylactic antibiotics, respectively, based on an established antibiotic policy. Three hundred ninety-five (87.8%) patients fulfilled a definition of the SIRS criteria. The frequency of the definitive categories was SIRS 21.8%, sepsis 14.4%, severe SIRS 8.4%, severe sepsis 13.6%, sterile shock 9.3%, and septic shock 20.2%. Patients with penetrating trauma had a significantly higher frequency of sepsis, severe sepsis, and septic shock (p < .01). The APACHE II score, risk of death, and number of organ failures increased significantly in both infective and noninfective groups with increasing severity of the inflammatory response. Sterile shock was associated with a significantly higher APACHE II score (p < .02), risk of death (p < .01), and number of organ failures (p = .03) compared with septic shock. Only sterile shock was associated with a significantly higher ISS (p < .01). Organ system failure was significantly (p < .001) higher in nonsurvivors compared with survivors in all categories. The only significant (p < .001) difference in mortality rate was found between patients in shock and all other categories.

CONCLUSIONS

The current definitions of SIRS, sepsis, and related disorders in critically injured patients without head trauma show a significant association with physiologic deterioration and increasing organ dysfunction. The only significant association with mortality, however, is the presence of shock. The definitions require refinement, with the possible inclusion of more objective gradations of organ system failure, if they are to be used for stratifying severity of illness in seriously injured patients.

Systemic inflammatory response syndrome

BACKGROUND

Localized inflammation is a physiological protective response which is generally tightly controlled by the body at the site of injury. Loss of this local control or an overly activated response results in an exaggerated systemic response which is clinically identified as systemic inflammatory response syndrome (SIRS). Compensatory mechanisms are initiated in concert with SIRS and outcome (resolution, multiple organ dysfunction syndrome or death) is dependent on the balance of SIRS and such compensatory mechanisms. No directed therapies have been successful to date in influencing outcome.

METHOD

This review examines the current spectrum and pathophysiology of SIRS.

RESULTS AND CONCLUSION

Further clinical and basic scientific research is required to develop the global picture of SIRS, its associated family of syndromes and their natural histories.