Predictors of outcome in cardiac surgical patients with prolonged intensive care stay

NO Addition during Gas Oxygenation Reduces Liver and Kidney Injury during Prolonged Cardiopulmonary Bypass

Objective. To evaluate the effect of NO added to the sweep gas of the oxygenator during cardiopulmonary bypass (CPB) on the liver and kidneys in pigs. Methods. An experiment was carried out on 10 pigs undergoing cardiac surgery using CPB. NO was added to the sweep gas of the oxygenator at a concentration of 100 ppm for the animals in the experimental group (CPB-NO, n = 5). Animals in the control group (CPB-contr, n = 5) did not receive NO in the sweep gas of the oxygenator. The CPB lasted 4 h, followed by postoperative monitoring for 12 h. To assess the injury to the liver and kidneys, the levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), bilirubin, creatinine, and neutrophil gelatinase-associated lipocalin (NGAL) were determined initially, at weaning from the CPB, and 6 and 12 h after weaning from the CPB. The glomerular filtration rate (GFR) was evaluated initially, at weaning from the CPB, and 6 and 12 h after weaning from the CPB. A pathomorphological study of the liver and kidneys was performed using semiquantitative morphometry. Results. The long four-hour period of CPB deliberately used in our experiment caused liver and kidney injury. In the CPB-contr group, an increase in the ALT concentration was found: 43 (34; 44) U/L at baseline to 82 (53; 99) U/L 12 h after CPB, p < 0.05. The AST concentration in the CPB-contr group increased from 25 (17; 26) U/L at baseline to 269 (164; 376) U/L 12 h after CPB, p < 0.05. We found no significant increase in the ALT and AST concentrations in the CPB-NO group. There were no significant differences in ALT and AST concentrations between the CPB-NO and CPB-contr groups at all the study time-points. In the CPB-contr group, an increase in the creatinine level was found from 131 (129; 133) µmol/L at baseline to 273 (241; 306) µmol/L 12 h after CPB, p < 0.05. We found no significant increase in creatinine level in the CPB-NO group. Creatinine levels in the CPB-NO group were significantly lower than in the CPB-contr group 12 h after weaning from CPB: 183 (168; 196) vs. 273 (241; 306) µmol/L; p = 0.008. The GFR in the CPB-NO group was significantly higher than in the CPB-contr group 6 h after weaning from CPB: 78.9 (77.8; 82.3) vs. 67.9 (62.3; 69.2) mL/min; p = 0.016. GFR was significantly higher in the CPB-NO group than in the CPB-contr group 12 h after weaning from CPB: 67.7 (65.5; 68.0) vs. 50.3 (48.7; 54.9) mL/min; p = 0.032. We found no significant differences between the study groups in the level of NGAL. We found several differences between the groups in the pathomorphological study. Conclusions. NO added to the sweep gas of the oxygenator reduces creatinine levels and increases GFR during prolonged CPB injury. Further research is required.

Analysis of the Performance of Daily Surgery Score (CASUS) in Patients with Mixed Racial Profile after Cardiac Surgery: A Single-Center Retrospective Study

OBJECTIVE

The aim was to look at the Cardiac Surgery Score (CASUS) assessment after cardiac surgery, and compare it with the intensive care unit (ICU) mortality and morbidity, in a racially diverse group of patients, in a single center.

DESIGN

Clinical retrospective study analyzing data from 319 patients over a 1-year duration.

SETTING

Cardiothoracic intensive care unit (CTICU) of a tertiary care center.

PARTICIPANTS

All patients who underwent cardiac surgery between January 1 and December 31, 2017.

INTERVENTIONS

Review of electronic patient records.

MEASUREMENTS AND RESULTS

Daily CASUS assessments (calculated on an online application and recorded on patient electronic records) were retrieved. The variables of CASUS used for the study were CASUS value on postoperative day 1 (POD1-CASUS), on death/discharge from CTICU (Dis-CASUS), mean of all CASUS values during CTICU stay (M-CASUS), and differential CASUS (Dif- CASUS) [CASUS POD 1 - CASUS on discharge]. The receiver operating characteristic (ROC) curve for the diagnostic level of POD 1-CASUS, indicating mortality, was calculated. A value of >6.5 for POD 1 CASUS had 80% sensitivity and 84% specificity, with area under the curve value 0.756 (95% confidence interval: 0.46 to 1). The mean values of POD1-CASUS (8.6 ± 6), M-CASUS (8.2 ± 5.2), and Dis-CASUS (7.8 ± 5.7) were significantly higher in cases of mortality, compared to the others. POD1-CASUS, M-CASUS, and Dis-CASUS were found to be statistically significantly elevated in patients with acute kidney injury (AKI) and postoperative stroke, and in those who were readmitted to the CTICU after initial discharge. Patients with POD1-CASUS ≥6.5 had a statistically significant association with mortality and postoperative morbidity (p < 0.05). Findings from multivariate logistic regression indicated that body mass index (BMI), ICU readmission, length of mechanical ventilation, and length of ICU stay remained associated significantly with POD1 CASUS ≥6.5.

CONCLUSION

This study found that CASUS on POD 1, mean values of CASUS during CTICU stay, and CASUS at death/discharge from CTICU predicted ICU mortality after cardiac surgery in this racially diverse group. The CASUS derivatives can be used to predict unfavorable outcomes after cardiac surgery. A POD1-CASUS value of 6.5 or more could signify mortality and postoperative morbidity.

Predictive Value of the Serum Albumin Level on Admission in Patients With Spontaneous Subarachnoid Hemorrhage

Objective: To determine the effect of the serum albumin level on admission in patients with spontaneous subarachnoid hemorrhage (SAH).

Methods: A total of 229 patients with SAH were divided into control and hypoalbuminemia groups. The serum albumin levels were measured. The data, including age, gender, co-existing medical conditions, risk factors, Hunt-Hess (H-H) grade on admission, Glasgow coma score (GCS) on admission, complications during hospitalizations, length of hospital stay, length of intensive care unit (ICU) stay, in-hospital mortality, survival rate, outcome at discharge, and the 6-month follow-up outcome, were compared between the two groups.

Results: Older age, an increased number of patients who consumed an excess of alcohol, and a lower GCS on admission were findings in the hypoalbuminemia group compared to the control group (p < 0.001). The ratio of patients with H-H grade I on admission in the hypoalbuminemia group was decreased compared to the control group (p < 0.05). Patients with hypoalbuminemia were more likely to be intubated, and have pneumonia and cerebral vasospasm than patients with a normal albumin level on admission (p < 0.001). Furthermore, the length of hospital and ICU stays were longer in the hypoalbuminemia group than the control group (p < 0.001). Hypoalbuminemia on admission significantly increased poor outcomes at discharge (p < 0.001). The number of patients with severe disability was increased and the recovery rate was decreased with respect to in-hospital outcomes in the hypoalbuminemia group than the control group (p < 0.001).

Conclusion: Hypoalbuminemia was shown to be associated with a poor prognosis in patients with SAH.

Characteristics and Survival of Patients with Acute Traumatic Spinal Cord Injury Above T6 with Prolonged Intensive Care Unit Stays

OBJECTIVE

To characterize patients with acute traumatic spinal cord injury (ATSCI) above T6 who were admitted to the intensive care unit (ICU) for ≥30 days and their 1-year mortality compared with patients admitted for <30 days.

METHODS

A retrospective observational study was performed on 211 patients with an acute traumatic spinal cord injury above T6 who were admitted to an ICU between 1998 and 2017. Multivariate logistic regression analysis was performed to determine the relationship between an ICU stay ≥30 days and mortality after ICU discharge.

RESULTS

Of patients, 29.4% were admitted to the ICU for ≥30 days, accounting for 53.4% of total days of ICU stays generated by all patients. An ICU stay ≥30 days was not identified as an independent risk factor for mortality (1-year survival: 88.5% vs. 88.1%; adjusted hazard ratio [HR] 0.80, P = 0.699). Variables identified as predictors of 1-year post-ICU discharge mortality were severity at admission according to the Acute Physiology and Chronic Health Evaluation II score (HR 1.18) and the American Spinal Injury Association Impairment Scale motor score (HR 0.97). Among patients who required invasive mechanical ventilation, a longer duration of the respiratory support was associated with increased mortality (HR 1.01).

CONCLUSIONS

Three out of 10 patients with acute traumatic spinal cord injury above T6 require prolonged stays in the ICU. Variables found to be associated with 1-year post-ICU discharge mortality in these patients were American Spinal Injury Association Impairment Scale motor score, severity, and greater duration of invasive mechanical ventilation, but not an ICU stay ≥30 days.

Intensive care outcome of left main stem disease surgery: A single center three years’ experience

BACKGROUND

Left main coronary artery (LMCA) supplies more than 80% of the left ventricle, and significant disease of this artery carries a high mortality unless intervened surgically. However, the influence of coronary artery bypass grafting (CABG) surgery on patients with LMCA disease on morbidity intensive care unit (ICU) outcomes needs to be explored. However, the impact of CABG surgery on the morbidity of the ICU population with LMCA disease is worth exploring.

AIM

To determine whether LMCA disease is a definitive risk factor of prolonged ICU stay as a primary outcome and early morbidity within the ICU stay as secondary outcome.

METHODS

Retrospective descriptive study with purposive sampling analyzing 399 patients who underwent isolated urgent or elective CABG. Patients were divided into 2 groups; those with LMCA disease as group 1 (75 patients) and those without LMCA disease as group 2 (324 patients). We correlated ICU outcome parameters including ICU length of stay, post-operative atrial fibrillation, acute kidney injury, re-exploration, perioperative myocardial infarction, post-operative bleeding in both groups.

RESULTS

Patients with LMCA disease had a significantly higher prevalence of diabetes (43.3% vs 29%, P = 0.001). However, we did not find a statistically significant difference with regards to ICU stay, or other morbidity and mortality outcome measures.

CONCLUSION

Post-operative performance of Patients with LMCA disease who underwent CABG were comparable to those without LMCA involvement. Diabetes was more prevalent in patients with LMCA disease. These findings may help in guiding decision making for future practice and stratifying the patients’ care.

The Impact of Initiation of an Intensivist-Led Patient Management Protocol on Outcomes After Cardiac Surgery

OBJECTIVES

Prolonged intensive care unit stay after cardiac surgery is associated with high mortality. The aim of this study was to evaluate the impact of the introduction of a quality improvement program under the supervision of an intensivist on the long-term mortality of high-risk patients with prolonged intensive care unit (ICU) stay after cardiac surgery.

DESIGN

Retrospective study of prospectively collected data.

SETTING

Cardiac surgery ICU.

PARTICIPANTS

A total of 7,549 patients after cardiac surgery.

INTERVENTIONS

Patients were divided into two periods: 2004 to 2007, before introducing the quality improvement program (3,315 patients), and 2009 to 2014, after introduction of the program (4,234 patients). In the period from 2004 to 2007, patients were divided into group I (ICU stay ≥ seven days), which included 242 patients, and group III (ICU stay < seven days), which included 3,073 patients. Also, in the period from 2009 to 2014 patients, were divided into group II (ICU stay ≥seven days), which included 326 patients, and group IV (ICU stay < seven days), which included 3,908 patients. Patient outcomes were compared. Follow-up was five years for each group.

MEASUREMENTS AND MAIN RESULTS

The European System for Cardiac Operative Risk Evaluation did not differ significantly among the groups. When comparing between group I and group II, 30-day mortality decreased significantly from 24.8% to 16.6%, six-month mortality from 27.3% to 19.3%, one-year mortality from 42.1% to 32.2%, 3-year mortality from 54.5% to 43.3%, and 5-year mortality from 61.2% to 51.8%. In comparing between group III and group IV, the authors did not observe a statistically significant decrease of mortality.

CONCLUSIONS

Intensivist-led patient management protocol is associated with decreased long-term mortality in high-risk patients with a prolonged ICU stay.

Effect of Goal-directed Hemodynamic Therapy in Postcardiac Surgery Patients

Background and aims

Early goal-directed therapy (EGDT) provides preset goals to be achieved by intravenous fluid therapy and inotropic therapy with earliest detection of change in the hemodynamic profile. Improved outcome in cardiac surgery patients has been shown by perioperative volume optimization, while postoperative intensive care unit (ICU) stay can be decreased by improving oxygen delivery. Our aim of this study was to study the outcome of EGDT in patients undergoing elective cardiac surgery.

Materials and methods

This is a prospective single institute study involving a total of 478 patients. Patients were divided into group I, who received standard hospital care, and group II, who received EGDT. Postoperatively, patients were observed in ICU for 72 hours. Hemodynamics, laboratory data, fluid bolus, inotrope score, complication, ventilatory time, and mortality data were collected.

Results

Postoperative ventilatory period (11.12 ± 10.11 vs 9.45 ± 8.87, p = 0.0719) and frequency of change in inotropes (1.900 ± 0.9 vs 1.19 ± 0.61, p = 0.0717) were lower in group II. Frequency of crystalloid boluses (1.33 ± 0.65 vs 1.75 ± 1.09, p = 0.0126), and quantity of packed cell volume (PCV) used (1.63 ± 1.03 vs 2.04 ± 1.42, p = 0.0364) were highly significant in group II. Use of colloids was higher in group II and was statistically significant (1.98 ± 1.99 vs 3.05 ± 2.17, p = 0.0012). The acute kidney injury (AKI) rate was (58 (23.10%) vs 30 (13.21%), p = 0.007) lower and statistically significant (p = 0.007) in group II.

Conclusion

Early goal-directed therapy reduces the postoperative ventilatory period, frequency of changes in inotropes, and incidence of AKI, and decreases ventilation hours, number of times inotropes changed, and AKI.

How to cite this article

Patel H, Parikh N, Shah R, Patel R, Thosani R, Shah P, et al. Effect of Goal-directed Hemodynamic Therapy in Postcardiac Surgery Patients. Indian J Crit Care Med 2020;24(5):321-326.

Survival, Quality of Life, and Functional Status Following Prolonged ICU Stay in Cardiac Surgical Patients: A Systematic Review

OBJECTIVES

Compared with noncardiac critical illness, critically ill postoperative cardiac surgical patients have different underlying pathophysiologies, are exposed to different processes of care, and thus may experience different outcome trajectories. Our objective was to systematically review the outcomes of cardiac surgical patients requiring prolonged intensive care with respect to survival, residential status, functional recovery, and quality of life in both hospital and long-term follow-up.

DATA SOURCES

MEDLINE, Embase, CINAHL, Web of Science, and Dissertations and Theses Global up to July 21, 2017.

STUDY SELECTION

Studies were included if they assessed hospital or long-term survival and/or patient-centered outcomes in adult patients with prolonged ICU stays following major cardiac surgery. After screening 10,159 citations, 114 articles were reviewed in full; a final 34 articles met criteria for data extraction.

DATA EXTRACTION

Two reviewers independently extracted data and assessed risk of bias using the National Institutes of Health Quality Assessment Tool for Observational Studies. Extracted data included the used definition of prolonged ICU stay, number and characteristics of prolonged ICU stay patients, and any comparator short stay group, length of follow-up, hospital and long-term survival, residential status, patient-centered outcome measure used, and relevant score.

DATA SYNTHESIS

The definition of prolonged ICU stay varied from 2 days to greater than 14 days. Twenty-eight studies observed greater in-hospital mortality among all levels of prolonged ICU stay. Twenty-five studies observed greater long-term mortality among all levels of prolonged ICU stay. Multiple tools were used to assess patient-centered outcomes. Long-term health-related quality of life and function was equivalent or worse with prolonged ICU stay.

CONCLUSIONS

We found consistent evidence that patients with increases in ICU length of stay beyond 48 hours have significantly increasing risk of hospital and long-term mortality. The significant heterogeneity in exposure and outcome definitions leave us unable to precisely quantify the risk of prolonged ICU stay on mortality and patient-centered outcomes.

Is elevated blood glucose a marker of occult tissue hypoperfusion in off-pump coronary artery bypass grafting?

Context

Hyperglycemia has been found to occur during myocardial infarction and cardiac surgery even in nondiabetic patients. These being essentially stressful processes associated with hypoperfusion, we decided to find a possible relationship between the occurrence of global tissue hypoperfusion (GTH) and elevated blood glucose level in adult nondiabetic patients undergoing elective off-pump coronary artery bypass grafting (CABG).

Aims

This study aims to observe for the occurrence of global tissue hypoperfusion and its effect on blood glucose level and whether raised blood glucose level can be used as a marker for GTH.

Design

Prospective, observational study.

Settings

Cardiothoracic operation theater and intensive care unit of a tertiary care teaching hospital.

Materials and Methods

The occurrence of global tissue hypoperfusion were detected with the help of combined markers of mixed venous oxygen saturation and arterial lactate level at various perioperative study points together with arterial blood glucose level. Blood glucose level compared between the patients with and without GTH.

Statistical Analysis Used

Numerical variables were compared between groups by Student's t-test and categorical variables by Fisher's exact test. Two-tailed P ≤ 0.05 was considered for statistically significant.

Results

The incidence of GTH was 67%. Blood glucose level was raised in patients with GTH at some study time points but with poor sensitivity and specificity values.

Conclusions

Global tissue hypoperfusion is a common occurrence in even nondiabetic patients undergoing elective off-pump CABG. A relationship exists between rise in blood glucose level and global tissue hypoperfusion in such patients, although it cannot be viewed as marker of the same.

The APACHE II Score as a Predictor of Mortality After Open Heart Surgery

Objective

The Acute Physiology and Chronic Health Evaluation (APACHE) severity of disease classification system, which is one of the most widely used scoring systems to predict mortality, is used for intensive care units (ICU) patients. This study aimed to evaluate the predictive ability of APACHE II for mortality in patients after undergoing cardiac surgery. We studied if APACHE II could successfully predict the outcome in post-cardiac surgery patients.

Methods

This study involved retrospective data collection of all adult patients who were admitted to Ordu State Hospital cardiovascular surgery ICU following cardiac surgery from August 2013 to December 2015. Area under the receiver operating characteristic (ROC) curve (AUC) values were calculated for the APACHE II model.

Results

During the two years of data collection, we included 600 patients with a mean age of 64.77±10.148 years. Of these, 180 (30.0%) were females. The ICU mortality rate was 8.33%, and the mean length of ICU stay was 4.210±6.913 days. The mean pre-operative EuroSCORE was 3.890±2.565, and the mean pre-operative APACHE II score was 6.790±3.617. The AUC values for APACHE II and EuroSCORE were 0.743 and 0.767, respectively.

Conclusion

The APACHE II model can be used to predict mortality in a Turkish population of patients who have undergone cardiac surgery.

The long-term quality of life in patients with persistent inflammation-immunosuppression and catabolism syndrome after severe acute pancreatitis: A retrospective cohort study

PURPOSE

To explore clinical characteristics and long-term quality of life (QOL) in severe acute pancreatitis (SAP) patients with persistent inflammation-immunosuppression and catabolism syndrome (PICS).

MATERIALS AND METHODS

SAP patients admitted to ICU were eligible for the retrospective cohort study if they needed prolonged intensive care (>14days). Post-ICU QOL was assessed by a questionnaire, including 36-item Short Form Health Survey (SF-36) and record of re-work in a long-term follow-up.

RESULTS

214 SAP patients were enrolled, in which 149 (69.6%) patients met the criteria of PICS. PICS patients had more complications and ICU days compared to non-PICS patients (P<0.001), and their post-ICU mortality was higher (P=0.046). When adjusted for confounders, PICS was independently associated with higher post-ICU mortality (hazard ratio 4.5; 95% CI, 1.2 to 16.3; P=0.024). The 36-item Short Form Health Survey (SF-36) score was lower for PICS group in six subscales (P<0.001). Only 28.8% patients in the PICS group returned to work compared to 60% patients in the non-PICS group (P=0.001) CONCLUSIONS: SAP patients with prolonged ICU stay had a high morbidity of PICS, which was a risk factor for the post-ICU mortality and poor long-term QOL.

A Mortality Study for ICU Patients using Bursty Medical Events

The study of patients in Intensive Care Units (ICUs) is a crucial task in critical care research which has significant implications both in identifying clinical risk factors and defining institutional guidances. The mortality study of ICU patients is of particular interest because it provides useful indications to healthcare institutions for improving patients experience, internal policies, and procedures (e.g. allocation of resources). To this end, many research works have been focused on the length of stay (LOS) for ICU patients as a feature for studying the mortality. In this work, we propose a novel mortality study based on the notion of burstiness, where the temporal information of patients longitudinal data is taken into consideration. The burstiness of temporal data is a popular measure in network analysis and time-series anomaly detection, where high values of burstiness indicate presence of rapidly occurring events in short time periods (i.e. burst). Our intuition is that these bursts may relate to possible complications in the patient's medical condition and hence provide indications on the mortality. Compared to the LOS, the burstiness parameter captures the temporality of the medical events providing information about the overall dynamic of the patients condition. To the best of our knowledge, we are the first to apply the burstiness measure in the clinical research domain. Our preliminary results on a real dataset show that patients with high values of burstiness tend to have higher mortality rate compared to patients with more regular medical events. Overall, our study shows promising results and provides useful insights for developing predictive models on temporal data and advancing modern critical care medicine.

Perioperative utility of goal-directed therapy in high-risk cardiac patients undergoing coronary artery bypass grafting: "A clinical outcome and biomarker-based study"

Goal-directed therapy (GDT) encompasses guidance of intravenous (IV) fluid and vasopressor/inotropic therapy by cardiac output or similar parameters to help in early recognition and management of high-risk cardiac surgical patients. With the aim of establishing the utility of perioperative GDT using robust clinical and biochemical outcomes, we conducted the present study. This multicenter randomized controlled study included 130 patients of either sex, with European system for cardiac operative risk evaluation ≥3 undergoing coronary artery bypass grafting on cardiopulmonary bypass. The patients were randomly divided into the control and GDT group. All the participants received standardized care; arterial pressure monitored through radial artery, central venous pressure (CVP) through a triple lumen in the right internal jugular vein, electrocardiogram, oxygen saturation, temperature, urine output per hour, and frequent arterial blood gas (ABG) analysis. In addition, cardiac index (CI) monitoring using FloTrac™ and continuous central venous oxygen saturation (ScVO₂) using PreSep™ were used in patients in the GDT group. Our aim was to maintain the CI at 2.5–4.2 L/min/m², stroke volume index 30–65 ml/beat/m², systemic vascular resistance index 1500–2500 dynes/s/cm⁵/m², oxygen delivery index 450–600 ml/min/m², continuous ScVO₂ >70%, and stroke volume variation <10%; in addition to the control group parameters such as CVP 6–8 mmHg, mean arterial pressure 90–105 mmHg, normal ABG values, oxygen saturation, hematocrit value >30%, and urine output >1 ml/kg/h. The aims were achieved by altering the administration of IV fluids and doses of inotropes or vasodilators. The data of sixty patients in each group were analyzed in view of ten exclusions. The average duration of ventilation (19.89 ± 3.96 vs. 18.05 ± 4.53 h, P = 0.025), hospital stay (7.94 ± 1.64 vs. 7.17 ± 1.93 days, P = 0.025), and Intensive Care Unit (ICU) stay (3.74 ± 0.59 vs. 3.41 ± 0.75 days, P = 0.012) was significantly less in the GDT group, compared to the control group. The extra volume added and the number of inotropic dose adjustments were significantly more in the GDT group. The two groups did not differ in duration of inotropic use, mortality, and other complications. The perioperative continuation of GDT affected the early decline in the lactate levels after 6 h in ICU, whereas the control group demonstrated a settling lactate only after 12 h. Similarly, the GDT group had significantly lower levels of brain natriuretic peptide, neutrophil gelatinase-associated lipocalin levels as compared to the control. The study clearly depicts the advantage of GDT for a favorable postoperative outcome in high-risk cardiac surgical patients.

Local Anaesthetic Toxicity after Bilateral Thoracic Paravertebral Block in Patients Undergoing Coronary Artery Bypass Surgery

We conducted a small pilot observational study of the effects of bilateral thoracic paravertebral block (BTPB) as an adjunct to perioperative analgesia in coronary artery bypass surgery patients. The initial ropivacaine dose prior to induction of general anaesthesia was 3 mg/kg, which was followed at the end of the surgery by infusion of ropivacaine 0.25% 0.1 ml/kg/hour on each side (e.g. total 35 mg/hour for a 70 kg person). The BTPB did not eliminate the need for supplemental opioids after CABG in the eight patients studied. Moreover, in spite of boluses that were within the manufacturer's recommendation for epidural and major nerve blocks, and an infusion rate that was only slightly higher than what appeared to be safe for epidural infusion, potentially toxic total plasma ropivacaine concentrations were common. We also could not exclude the possibility that the high ropivacaine concentrations were contributing to postoperative mental state changes in the postoperative period. Also, one patient developed local anaesthetic toxicity after the bilateral paravertebral dose. As a result, the study was terminated early after four days. The question of whether paravertebral block confers benefits in cardiac surgery remains unanswered. However, we believe that the bolus dosage and the injection rate we used for BTPB were both too high, and caution other clinicians against the use of these doses. Future studies on the use of BTPB in cardiac surgery patients should include reduced ropivacaine doses injected over longer periods.

Survival outcomes after prolonged intensive care unit length of stay among trauma patients: The evidence for never giving up

BACKGROUND

Prolonged intensive care unit length of stay (ICU-LOS) is associated with high mortality for medical and surgical patients. Existing literature suggests that this may not be true for trauma patients. The objective of this study was to determine mortality associated with varying ICU-LOS among trauma patients and to assess for independent predictors of mortality.

METHODS

Adult ICU patients (16-64 years) in the National Trauma Data Bank (2007-2012) were categorized by ICU-LOS: 1, 2-9, 10-40, and >40 days (determined based on inflection points). Multivariable logistic regression was used to determine associations with mortality for each. Models accounted for clustering of patients within hospitals and potential confounding associated with: age, gender, race/ethnicity, insurance status, Injury Severity Score, blunt/penetrating injury, Glasgow Coma Scale, in-hospital complications, ventilator dependency, and emergency department disposition.

RESULTS

Among the 596,598 patients included, 6.5% (n = 38,812) died. Mortality varied with ICU-LOS: 9.9%, 4.9%, 6.6%, and 9.8%. Age >35 years was a significant predictor of mortality in each. Injury Severity Score and the Glasgow Coma Scale independently predicted mortality in patients with LOS ≤40 days as did penetrating injuries, cardiac arrest, and renal failure. Identification with non-Hispanic black race/ethnicity was also consistently significant. Once patients survived 9 days, mortality steadily decreased, remaining relatively stable until 40 days. Thereafter, trauma patients continued to demonstrate high survival with >87% remaining alive in the ICU >90 days.

CONCLUSION

The results reveal that in contrast to expectations of high mortality associated with prolonged ICU-LOS, critically injured adult trauma patients who do not die within the first few days demonstrate an enhanced ability to survive, with an overall survival of >92% and maintained at >85% among extreme ICU-LOS (>40 days). The data advocate the utility of aggressive critical-care support for trauma patients, irrespective of duration of ICU stay.

Relationship Between ICU Length of Stay and Long-Term Mortality for Elderly ICU Survivors

OBJECTIVES

To evaluate the association between length of ICU stay and 1-year mortality for elderly patients who survived to hospital discharge in the United States.

DESIGN

Retrospective cohort study of a random sample of Medicare beneficiaries who survived to hospital discharge, with 1- and 3-year follow-up, stratified by the number of days of intensive care and with additional stratification based on receipt of mechanical ventilation.

INTERVENTIONS

None.

PATIENTS

The cohort included 34,696 Medicare beneficiaries older than 65 years who received intensive care and survived to hospital discharge in 2005.

MEASUREMENTS AND MAIN RESULTS

Among 34,696 patients who survived to hospital discharge, the mean ICU length of stay was 3.4 days (± 4.5 d). Patients (88.9%) were in the ICU for 1-6 days, representing 58.6% of ICU bed-days. Patients (1.3%) were in the ICU for 21 or more days, but these patients used 11.6% of bed-days. The percentage of mechanically ventilated patients increased with increasing length of stay (6.3% for 1-6 d in the ICU and 71.3% for ≥ 21 d). One-year mortality was 26.6%, ranging from 19.4% for patients in the ICU for 1 day, up to 57.8% for patients in the ICU for 21 or more days. For each day beyond 7 days in the ICU, there was an increased odds of death by 1 year of 1.04 (95% CI, 1.03-1.05) irrespective of the need for mechanical ventilation.

CONCLUSIONS

Increasing ICU length of stay is associated with higher 1-year mortality for both mechanically ventilated and non-mechanically ventilated patients. No specific cutoff was associated with a clear plateau or sharp increase in long-term risk.

Intensive Care Unit Stay of More than 14 Days after Cardiac Surgery is Associated with Non-cardiac Organ Failure

Some studies have shown an association between a prolonged intensive care unit (ICU) stay and risk factors such as mediastinal re-exploration, advanced age, low ejection fraction, lung disease and organ failure. The aim of this retrospective study was first to evaluate peri-operative risk factors ( n = 2683) and secondly to evaluate long-term survival ( n = 2563) in cardiac surgery patients with an ICU stay > 14 days. Long-term survival was assessed in an observational 3-year follow-up study. An ICU stay of > 14 days was associated independently with respiratory failure and dialysis-dependent acute renal failure, and with a significantly lower survival rate. Since an ICU stay is associated with a higher hospital and long-term mortality, measures should be taken throughout the entire hospital stay to identify and reduce the risk of organ failure.

Role of admission serum albumin levels in patients with intracerebral hemorrhage

Low serum albumin levels have been reported to be an independent predictor of increased morbidity and mortality in multiple disease conditions. The aim of our study was to identify the impact of low serum albumin levels on mortality and outcomes at discharge in patients with intracerebral hemorrhage. We retrospectively reviewed our prospective database of patients with intracerebral hemorrhage from January 2010 to December 2011. Patients were dichotomized into two groups based on their serum albumin levels upon admission. Hypoalbuminemia was defined as serum albumin levels ≤3.4 g/dl. The two groups were compared using Fisher's exact test for categorical variables and t test for continuous variables. Poor outcome was defined as death or discharge to a long-term nursing facility (modified Rankin Score 4-6). Out of 97 patients admitted with intracerebral hemorrhage, 90 met our inclusion criteria (42 had normal levels and 48 had hypoalbuminemia). The baseline characteristics, risk factors, etiology, location and volume of intracerebral hemorrhage, admission blood glucose, white cell count, length of hospital stay, length of intensive care unit stay, and complications were similar between both groups. Although admission hypoalbuminemia did not impact in-hospital mortality (28 vs 24 %, p = 0.635), there was a significant increase in poor outcomes at discharge (59 vs 31 %, p = 0.009) (OR 1.8; 95 % CI; 1.2-2.8). Similar to other diseases, hypoalbuminemia was associated with poor functional outcomes in patients with intracerebral hemorrhage. This will need to be confirmed in larger prospective studies before adopting therapeutic and preventive strategies in future.

Association of Urinary Cadmium with Mortality in Patients at a Coronary Care Unit

BACKGROUND

Determine the effect of the day 1 urinary excretion of cadmium (D1-UE-Cd) on mortality of patients admitted to a coronary care unit (CCU).

METHODS

A total of 323 patients were enrolled in this 6-month study. Urine and blood samples were taken within 24 h after CCU admission. Demographic data, clinical diagnoses, and hospital mortality were recorded. The scores of established systems for prediction of mortality in critically ill patients were calculated.

RESULTS

Compared with survivors (n = 289), non-survivors (n = 34) had higher levels of D1-UE-Cd. Stepwise multiple linear regression analysis indicated that D1-UE-Cd was positively associated with pulse rate and level of aspartate aminotransferase, but negatively associated with serum albumin level. Multivariate Cox analysis, with adjustment for other significant variables and measurements from mortality scoring systems, indicated that respiratory rate and D1-UE-Cd were independent and significant predictors of mortality. For each 1 μg/day increase of D1-UE-Cd, the hazard ratio for CCU mortality was 3.160 (95% confidence interval: 1.944-5.136, p < 0.001). The chi-square value of Hosmer-Lemeshow goodness-of-fit test for D1-UE-Cd was 10.869 (p = 0.213). The area under the receiver operating characteristic curve for D1-UE-Cd was 0.87 (95% confidence interval: 0.81-0.93).

CONCLUSIONS

The D1-UE-Cd, an objective variable with no inter-observer variability, accurately predicted hospital mortality of CCU patients and outperformed other established scoring systems. Further studies are needed to determine the physiological mechanism of the effect of cadmium on mortality in CCU patients.

Scoring Systems for Outcome Prediction in a Cardiac Surgical Intensive Care Unit: A Comparative Study

BACKGROUND

Most scoring systems used to predict clinical outcome in critical care were not designed for application in cardiac surgery patients.

OBJECTIVES

To compare the predictive ability of the most widely used scoring systems (Acute Physiology and Chronic Health Evaluation [APACHE] II, Simplified Acute Physiology Score [SAPS] II, and Sequential Organ Failure Assessment [SOFA]) and of 2 specialized systems (European System for Cardiac Operative Risk Evaluation [EuroSCORE] II and the cardiac surgery score [CASUS]) for clinical outcome in patients after cardiac surgery.

METHODS

Consecutive patients admitted to a cardiac surgical intensive care unit (CSICU) were prospectively studied. Data on the preoperative condition, intraoperative parameters, and postoperative course were collected. EuroSCORE II, CASUS, and scores from 3 general severity-scoring systems (APACHE II, SAPS II, and SOFA) were calculated on the first postoperative day. Clinical outcome was defined as 30-day mortality and in-hospital morbidity.

RESULTS

A total of 150 patients were included. Thirty-day mortality was 6%. CASUS was superior in outcome prediction, both in relation to discrimination (area under curve, 0.89) and calibration (Brier score = 0.043, χ(2) = 2.2, P = .89), followed by EuroSCORE II for 30-day mortality (area under curve, 0.87) and SOFA for morbidity (Spearman ρ= 0.37 and 0.35 for the CSICU length of stay and duration of mechanical ventilation, respectively; Wilcoxon W = 367.5, P = .03 for probability of readmission to CSICU).

CONCLUSIONS

CASUS can be recommended as the most reliable and beneficial option for benchmarking and risk stratification in cardiac surgery patients.

A fiberoptic sensor for tissue carbon dioxide monitoring

We present a new fiberoptic carbon dioxide sensor for transcutaneous and mucosa (indwelling) blood gas monitoring. The sensor is based on optical fluorescence of molecules sensitive to pH changes associated with dissolved CO2. A three layer chemical coating was dip-coated onto the distal tip of an optical fiber (600μm core radius). It contained the 50mg/ml `polym H7', a coating polymer bonded to a fluorescence indicator dye, along with 125mg/ml of the transfer agent tetraoctylammonium hydroxide (TONOH). Light from a blue (460 nm) LED was launched into the fiber to excite the sensing film. The sensing film fluoresced green (530 nm), the intensity of which decreased in the presence of CO2. The sensor was tested in vitro, finding a correlation between change in fluorescence (in AU) and aqueous CO2 concentration with a minimum detection threshold of 40%. The sensor is being developed for medical applications where its small size and ability to continuously monitor the partial pressure of CO2 (PCO2) will make it an extremely useful diagnostic tool.

A straightforward approach to designing a scoring system for predicting length-of-stay of cardiac surgery patients

Background

Length-of-stay prediction for cardiac surgery patients is a key point for medical management issues, such as optimization of resources in intensive care units and operating room scheduling. Scoring systems are a very attractive family of predictive models, but their retraining and updating are generally critical. The present approach to designing a scoring system for predicting length of stay in intensive care aims to overcome these difficulties, so that a model designed in a given scenario can easily be adjusted over time or for internal purposes.

Methods

A naïve Bayes approach was used to develop a simple scoring system. A set of 36 preoperative, intraoperative and postoperative variables collected in a sample of 3256 consecutive adult patients undergoing heart surgery were considered as likely risk predictors. The number of variables was reduced by selecting an optimal subset of features. Scoring system performance was assessed by cross-validation.

Results

After the selection process, seven variables were entered in the prediction model, which showed excellent discrimination, good generalization power and suitable sensitivity and specificity. No significant difference was found between AUC of the training and testing sets. The 95% confidence interval for AUC estimated by the BCa bootstrap method was [0.841, 0.883] and [0.837, 0.880] in the training and testing sets, respectively. Chronic dialysis, low postoperative cardiac output and acute myocardial infarction proved to be the major risk factors.

Conclusions

The proposed approach produced a simple and trustworthy scoring system, which is easy to update regularly and to customize for other centers. This is a crucial point when scoring systems are used as predictive models in clinical practice.

The association between ASA status and other risk stratification models on postoperative intensive care unit outcomes

BACKGROUND

There is limited medical literature investigating the association between perioperative risk stratification methods and surgical intensive care unit (SICU) outcomes. Our hypothesis contends that routine assessments such as higher ASA physical status classification, surgical risk as defined by American College of Cardiology/American Heart Association guidelines, and simplified Revised Cardiac Index (SRCI) can reliably be associated with SICU outcomes.

METHODS

We performed a chart review of all patients 18 years or older admitted to the SICU between October 1, 2010, and March 1, 2011. We collected demographic and preoperative clinical data: age, sex, ASA physical status class, surgical risk, and SRCI. Outcome data included our primary end point, SICU length of stay, and secondary end points: mechanical ventilation and vasopressor treatment duration, number of acquired organ dysfunctions (NOD), readmission to the intensive care unit (ICU) within 7 days, SICU mortality, and 30-day mortality. Regression analysis and nonparametric tests were used, and P < 0.05 was considered significant.

RESULTS

We screened 239 patients and included 220 patients in the study. The patients' mean age was 58 ± 16 years. There were 32% emergent surgery and 5% readmissions to the SICU within 7 days. The SICU mortality and the 30-day mortality were 3.2%. There was a significant difference between SICU length of stay (2.9 ± 2.1 vs 5.9 ± 7.4, P = 0.007), mechanical ventilation (0.9 ± 2.0 vs 3.4 ± 6.8, P = 0.01), and NOD (0 [0-2] vs 1 [0-5], P < 0.001) based on ASA physical status class (≤ 2 vs ≥ 3). Outcomes significantly associated with ASA physical status class after adjusting for confounders were: SICU length of stay (incidence rate ratio [IRR] = 1.79, 95% confidence interval [CI], 1.35-2.39, P < 0.001), mechanical ventilation (IRR = 2.57, 95% CI, 1.69-3.92, P < 0.001), vasopressor treatment (IRR = 3.57, 95% CI, 1.84-6. 94, P < 0.001), NOD (IRR = 1.71, 95% CI, 1.46-1.99, P < 0.001), and readmission to ICU (odds ratio = 3.39, 95% CI, 1.04-11.09, P = 0.04). We found significant association between surgery risk and NOD (IRR = 1.56, 95% CI, 1.29-1.89, P < 0.001, and adjusted IRR = 1.31, 95% CI, 1.05-1.64, P = 0.02). SRCI was not significantly associated with SICU outcomes.

CONCLUSIONS

Our study revealed that ASA physical status class is associated with increased SICU length of stay, mechanical ventilation, vasopressor treatment duration, NOD, readmission to ICU, and surgery risk is associated with NOD.

Impact of major non-cardiac complications on outcome following cardiac surgery procedures: logistic regression analysis in a very recent patient cohort

OBJECTIVES

In this study, we sought to analyse the incidence of major non-cardiac complications and their impact on survival following cardiac surgery procedures in a contemporary patient cohort. We further determined independent predictors of perioperative mortality and created a logistic regression model for prediction of outcome after the occurrence of these complications.

METHODS

Prospectively collected data of 5318 consecutive adult patients (mean age 68.9±11.0 years; 29.3% [n=1559] female) undergoing cardiac surgery from January 2009 to May 2012 were retrospectively analysed. Outcome measures were six major non-cardiac complications including respiratory failure, dialysis-dependent renal failure, deep sternal wound infection (DSWI), cerebrovascular accident (CVA), gastrointestinal complications (GIC) and sepsis and their impact on perioperative mortality and hospital length of stay using multivariate regression models. The discriminatory power was evaluated by calculating the area under the receiver operating characteristic curves (C statistic).

RESULTS

A total of 1321 complications were observed in 846 (15.9%) patients: respiratory failure (n=432; 8.1%), dialysis-dependent renal failure (n=295; 5.5%), GIC (n=154; 2.9%), CVA (n=151; 2.8%), DSWI (n=146; 2.7%) and sepsis (n=143; 2.7%). Perioperative mortality was 17.0% in patients with at least one major non-cardiac complication and correlated with the number of complications (single, 9.7%; n=53/549; double, 24.0%; n=44/183; ≥3, 41.2%; n=47/114, P<0.001). Six preoperative and four postoperative independent predictors of operative mortality were identified (age (odds ratio [OR] 1.8; 95% confidence interval [CI] 1.3-2.4), peripheral vascular disease (OR 2.6; 95% CI 1.6-4.2), pulmonary hypertension (OR 2.7; 95% CI 1.5-4.9), atrial fibrillation (OR 1.5; 95% CI 1.0-2.3), emergency (OR 5.0; 95% CI 3.4-7.2), other procedures than CABG (OR 1.5; 95% CI 1.0-2.1), postoperative dialysis (OR 4.0; 95% CI 2.6-6.1), sepsis (OR 3.4; 95% CI 2.0-5.6), respiratory failure (OR 3.2; 95% CI 2.2-4.9), GIC (OR 3.2; 95% CI 1.9-5.3)) and included in the logistic model, which accurately predicted outcome (C statistic, 0.892; 95% CI 0.868-0.916). Length of hospital stay was significantly increased according to the number of complications (single: median 15 (IQR 10-24) days, double: 16 (IQR 8-28) days, ≥3: 20 (IQR 13-39) days, P<0.001).

CONCLUSIONS

With a worsening in the risk profile of patients undergoing cardiac surgery, an increasing number of patients develop major complications leading to increased length of stay and mortality, which is correlated to the number and severity of these complications. Our predictive model based on preoperative and postoperative variables allowed us to determine with accuracy the perioperative mortality in critically ill patients after cardiac surgery.

Haemodynamic goal-directed therapy in cardiac and vascular surgery. A systematic review and meta-analysis

In cardiovascular surgery, reduced organ perfusion and oxygen delivery contribute to increased postoperative morbidity and prolonged intensive care unit stay. Goal-directed therapy (GDT), a perioperative haemodynamic strategy aiming to increase cardiac output, is helpful in preventing postoperative complications, but studies in the context of cardiovascular surgery have produced conflicting results. The purpose of the present meta-analysis is to determine the effects of perioperative haemodynamic goal-directed therapy on mortality and morbidity in cardiac and vascular surgery. MEDLINE, EMBASE, The Cochrane Library and the DARE databases were searched until July 2011. Randomized controlled trials reporting on adult cardiac or vascular surgical patients managed with perioperative GDT or according to routine haemodynamic practice were included. Primary outcome measures were mortality and morbidity. Data synthesis was obtained by using odds ratio (OR) with 95% confidence interval (CI) by a random effects model. An OR <1 favoured GDT. Statistical heterogeneity was assessed by Q and I(2) statistics. Eleven articles (five cardiac surgery and six vascular procedures), enrolling a total sample of 1179 patients, were included in the analysis. As compared with routine haemodynamic practice, perioperative GDT did not reduce mortality in either cardiac or vascular surgery (pooled OR 0.87; 95% CI 0.37-2.02; statistical power 64%). GDT significantly reduced the number of cardiac patients with complications (OR 0.34; 95% CI 0.18-0.63; P = 0.0006), but no effect was observed in vascular patients (OR, 0.84; 95% CI 0.45-1.56; P = 0.58). Perioperative GDT prevents postoperative complications in cardiac surgery patients, while it has no effect in vascular surgery. The different characteristics and comorbidities of the population enrolled could explain these conflicting results. More trials conforming to the characteristics of low-risk-of-bias studies and enrolling a larger and well-defined population of patients are needed to better clarify the effect of GDT in the specific setting of cardiovascular surgery.

The Going Home Initiative: Getting Critical Care Patients Home With Hospice

Although considerable effort is being directed at providing patients and their families with a “good death,” most patients in intensive care units, if given the choice, would prefer to die at home. With little guidance from the literature, the palliative care committee of an intensive care unit developed guidelines to get patients home from the intensive care unit to die. In the past few years, the unit has transferred many patients home with hospice care, much to the delight of their families. Although several obstacles to achieving this goal exist, the unit has achieved success in a small-scale implementation of its Going Home Initiative.

Logistic Organ Dysfunction Score (LODS): a reliable postoperative risk management score also in cardiac surgical patients?

BACKGROUND

The original Logistic Organ Dysfunction Sore (LODS) excluded cardiac surgery patients from its target population, and the suitability of this score in cardiac surgery patients has never been tested. We evaluated the accuracy of the LODS and the usefulness of its daily measurement in cardiac surgery patients. The LODS is not a true logistic scoring system, since it does not use β-coefficients.

METHODS

This prospective study included all consecutive adult patients who were admitted to the intensive care unit (ICU) after cardiac surgery between January 2007 and December 2008. The LODS was calculated daily from the first until the seventh postoperative day. Performance was assessed with Hosmer-Lemeshow (HL) goodness-of-fit test (calibration) and receiver operating characteristic (ROC) curves (discrimination) from ICU admission day until day 7. The outcome measure was ICU mortality.

RESULTS

A total of 2801 patients (29.6% female) with a mean age of 66.4 ± 10.7 years were included. The ICU mortality rate was 5.2% (n = 147). The mean stay on the ICU was 4.3 ± 6.8 days. Calibration of the LODS was good with no significant difference between expected and observed mortality rates on any day (p ≥ 0.05). The initial LODS had an area under the ROC curve (AUC) of 0.81. The AUC was best on ICU day 3 with a value of 0.93, and declined to 0.85 on ICU day 7.

CONCLUSIONS

Although the LODS has not previously been validated for cardiac surgery patients it showed reasonable accuracy in prediction of ICU mortality in patients after cardiac surgery.

A comparative study of four intensive care outcome prediction models in cardiac surgery patients

Background

Outcome prediction scoring systems are increasingly used in intensive care medicine, but most were not developed for use in cardiac surgery patients. We compared the performance of four intensive care outcome prediction scoring systems (Acute Physiology and Chronic Health Evaluation II [APACHE II], Simplified Acute Physiology Score II [SAPS II], Sequential Organ Failure Assessment [SOFA], and Cardiac Surgery Score [CASUS]) in patients after open heart surgery.

Methods

We prospectively included all consecutive adult patients who underwent open heart surgery and were admitted to the intensive care unit (ICU) between January 1^st 2007 and December 31^st 2008. Scores were calculated daily from ICU admission until discharge. The outcome measure was ICU mortality. The performance of the four scores was assessed by calibration and discrimination statistics. Derived variables (Mean- and Max- scores) were also evaluated.

Results

During the study period, 2801 patients (29.6% female) were included. Mean age was 66.9 ± 10.7 years and the ICU mortality rate was 5.2%. Calibration tests for SOFA and CASUS were reliable throughout (p-value not < 0.05), but there were significant differences between predicted and observed outcome for SAPS II (days 1, 2, 3 and 5) and APACHE II (days 2 and 3). CASUS, and its mean- and maximum-derivatives, discriminated better between survivors and non-survivors than the other scores throughout the study (area under curve ≥ 0.90). In order of best discrimination, CASUS was followed by SOFA, then SAPS II, and finally APACHE II. SAPS II and APACHE II derivatives had discrimination results that were superior to those of the SOFA derivatives.

Conclusions

CASUS and SOFA are reliable ICU mortality risk stratification models for cardiac surgery patients. SAPS II and APACHE II did not perform well in terms of calibration and discrimination statistics.

Pretreatment serum albumin as a predictor of cancer survival: a systematic review of the epidemiological literature

Background

There are several methods of assessing nutritional status in cancer of which serum albumin is one of the most commonly used. In recent years, the role of malnutrition as a predictor of survival in cancer has received considerable attention. As a result, it is reasonable to investigate whether serum albumin has utility as a prognostic indicator of cancer survival in cancer. This review summarizes all available epidemiological literature on the association between pretreatment serum albumin levels and survival in different types of cancer.

Methods

A systematic search of the literature using the MEDLINE database (January 1995 through June 2010) to identify epidemiologic studies on the relationship between serum albumin and cancer survival. To be included in the review, a study must have: been published in English, reported on data collected in humans with any type of cancer, had serum albumin as one of the or only predicting factor, had survival as one of the outcome measures (primary or secondary) and had any of the following study designs (case-control, cohort, cross-sectional, case-series prospective, retrospective, nested case-control, ecologic, clinical trial, meta-analysis).

Results

Of the 29 studies reviewed on cancers of the gastrointestinal tract, all except three found higher serum albumin levels to be associated with better survival in multivariate analysis. Of the 10 studies reviewed on lung cancer, all excepting one found higher serum albumin levels to be associated with better survival. In 6 studies reviewed on female cancers and multiple cancers each, lower levels of serum albumin were associated with poor survival. Finally, in all 8 studies reviewed on patients with other cancer sites, lower levels of serum albumin were associated with poor survival.

Conclusions

Pretreatment serum albumin levels provide useful prognostic significance in cancer. Accordingly, serum albumin level could be used in clinical trials to better define the baseline risk in cancer patients. A critical gap for demonstrating causality, however, is the absence of clinical trials demonstrating that raising albumin levels by means of intravenous infusion or by hyperalimentation decreases the excess risk of mortality in cancer.

A bootstrap approach for assessing the uncertainty of outcome probabilities when using a scoring system

Background

Scoring systems are a very attractive family of clinical predictive models, because the patient score can be calculated without using any data processing system. Their weakness lies in the difficulty of associating a reliable prognostic probability with each score. In this study a bootstrap approach for estimating confidence intervals of outcome probabilities is described and applied to design and optimize the performance of a scoring system for morbidity in intensive care units after heart surgery.

Methods

The bias-corrected and accelerated bootstrap method was used to estimate the 95% confidence intervals of outcome probabilities associated with a scoring system. These confidence intervals were calculated for each score and each step of the scoring-system design by means of one thousand bootstrapped samples. 1090 consecutive adult patients who underwent coronary artery bypass graft were assigned at random to two groups of equal size, so as to define random training and testing sets with equal percentage morbidities. A collection of 78 preoperative, intraoperative and postoperative variables were considered as likely morbidity predictors.

Results

Several competing scoring systems were compared on the basis of discrimination, generalization and uncertainty associated with the prognostic probabilities. The results showed that confidence intervals corresponding to different scores often overlapped, making it convenient to unite and thus reduce the score classes. After uniting two adjacent classes, a model with six score groups not only gave a satisfactory trade-off between discrimination and generalization, but also enabled patients to be allocated to classes, most of which were characterized by well separated confidence intervals of prognostic probabilities.

Conclusions

Scoring systems are often designed solely on the basis of discrimination and generalization characteristics, to the detriment of prediction of a trustworthy outcome probability. The present example demonstrates that using a bootstrap method for the estimation of outcome-probability confidence intervals provides useful additional information about score-class statistics, guiding physicians towards the most convenient model for predicting morbidity outcomes in their clinical context.

Effect of length of stay in intensive care unit on hospital and long-term mortality of critically ill adult patients

BACKGROUND

Critical illness leading to prolonged length of stay (LOS) in an intensive care unit (ICU) is associated with significant mortality and resource utilization. This study assessed the independent effect of ICU LOS on in-hospital and long-term mortality after hospital discharge.

METHODS

Clinical and mortality data of 22 298 patients, aged 16 yr and older, admitted to ICU between 1987 and 2002 were included in this linked-data cohort study. Cox's regression with restricted cubic spline function was used to model the effect of LOS on in-hospital and long-term mortality after adjusting for age, gender, acute physiology score (APS), maximum number of organ failures, era of admission, elective admission, Charlson's co-morbidity index, and diagnosis. The variability each predictor explained was calculated by the percentage of the chi(2) statistic contribution to the total chi(2) statistic.

RESULTS

Most hospital deaths occurred within the first few days of ICU admission. Increasing LOS in ICU was not associated with an increased risk of in-hospital mortality after adjusting for other covariates, but was associated with an increased risk of long-term mortality after hospital discharge. The variability on the long-term mortality effect associated with ICU LOS (2.3%) appeared to reach a plateau after the first 10 days in ICU and was not as important as age (35.8%), co-morbidities (18.6%), diagnosis (10.9%), and APS (3.6%).

CONCLUSIONS

LOS in ICU was not an independent risk factor for in-hospital mortality, but it had a small effect on long-term mortality after hospital discharge after adjustment for other risk factors.

Serum albumin as an outcome predictor in hospital emergency medical admissions

BACKGROUND

To examine the relationship between admission serum albumin and 30-day mortality during an emergency medical admission.

METHODS

An analysis was performed of all emergency medical patients admitted to St. James's Hospital (SJH), Dublin between 1st January 2002 and 31st December 2008, using the hospital in-patient enquiry (HIPE) system, linked to the patient administration system, and laboratory datasets. Mortality was defined as an in-hospital death within 30 days. Logistic regression was used to calculate unadjusted and adjusted odds ratios (ORs) and 95% confidence intervals for defined albumin subsets.

FINDINGS

Univariate analysis using predefined criteria based on distribution, identified the groups of <10% and between 10 and 25% of the serum albumin frequency distribution as at increased mortality risk. Their mortality rates were 31.7% and 15.4% respectively; their unadjusted odds rates were 6.35 (5.68, 7.09) and 2.11 (1.90, 2.34). Patients in the lowest 25% of the distribution had a 30-day mortality of 19.9% and this significantly increased risk persisted, after adjustment for other outcome predictors including co-morbidity and illness severity (OR 2.95 (2.49, 3.48): p<0.0001).

INTERPRETATION

Serum albumin is predictive of 30-day mortality in emergency medical patients; mortality is non-linearly related to baseline albumin. The disproportionate increased death risk for patients in the lowest 25% of the frequency distribution (<36 g/L) is not due to co-morbidity factors or acute illness severity.

Cadmium excretion predicting hospital mortality and illness severity of critically ill medical patients

OBJECTIVE

To determine the prognostic value of day 1 urine excretion of cadmium (1st DUE-Cd) for predicting outcomes in intensive care unit (ICU) patients.

DESIGN

Prospective study.

SETTING

ICUs in Chang Gung Memorial Hospital, Lin-Kou Medical Center, Taiwan, ROC.

PATIENTS

Two hundred one ICU patients.

INTERVENTIONS

Urine and blood samples were taken within 24 hours after admission.

MEASUREMENTS AND MAIN RESULTS

Disease severity, hospital mortality, and number of organ failures were evaluated in each medical ICU patient. Stepwise multiple linear regression analysis indicated that a history of chronic hepatitis, serum albumin, and glutamic-pyruvic transaminase were significantly related to 1st DUE-Cd after adjusting for other related variables. Cox multivariate analysis revealed that serum blood urea nitrogen level and ICU 1st DUE-Cd were significantly related to hospital mortality after other risk factors and scoring systems were adjusted. Each 1-microg increase in ICU 1st DUE-Cd was associated with a 7% increase in hospital mortality rate. All patients with poisoning magnitude of cadmium excretion (>10 microg/day) died, except one and those with normal cadmium excretion survived. Chi-square values of the Hosmer-Lemeshow goodness-of-fit test were 6.936 (p = 0.544), and area under the receiver operating characteristic curve was 0.868 (95% confidence intervals: 0.82-0.92) for ICU 1st DUE-Cd.

CONCLUSIONS

The ICU 1st DUE-Cd may predict hospital mortality in critically ill medical patients. Because of excess mortality and relatively small sample size, the predictive role of DUE-Cd needs further external validation.

Hepatic and renal protection during cardiac surgery

Hepatic injury in cardiac surgery is a rare complication but is associated with significant morbidity and mortality. A high index of suspicion postoperatively will lead to earlier treatment directed at eliminating or minimizing ongoing hepatic injury while preventing additional metabolic stress from ischemia, hemorrhage, or sepsis. The evidence-basis for perioperative renal risk factors remains hampered by the inconsistent definitions for renal injury. Although acute kidney injury (as defined by the Risk, Injury, Failure, Loss, End-stage criteria) has become accepted, it does not address pathogenesis and bears little relevance to cardiac surgery. Although acute renal failure requiring renal replacement therapy after cardiac surgery is rare, it has a devastating impact on morbidity and mortality, and further studies on protective strategies are essential.

Coronary artery bypass grafting is associated with excellent long-term survival and quality of life: a prospective cohort study

BACKGROUND

We investigated the long-term outcome of coronary artery bypass grafting both in terms of survival and quality of life.

METHODS

Ten-year postsurgery survival was collated on patients undergoing coronary artery bypass grafting from 1994 to 1996, and quality of life was assessed using EQ-5D and a quality-of-life thermometer. We analyzed data from 1,180 patients. Mean age was 61 years, and 79% had triple-vessel disease.

RESULTS

Thirty-day mortality was 3.3% (1.8% elective). Mean time to censorship for survivors was 9.9 years (range, 8.1 to 12.3 years). Ten-year survival was 66% across all patients, 70% for elective patients. Ten-year cardiac survival was 82%. Percutaneous intervention was required in 25 patients in the subsequent 10 years (2%), and only 4 required redo coronary artery bypass grafting (0.3%); 59% of patients reported no angina, and 88% of patients had grade II angina or better. Of 621 patients who were assessed for quality of life at 10 years, 530 (85%) had a quality of life within a 95% confidence interval of the score found in the general population with similar age. Poor quality of life was reported in 91 patients (14.7%). Significant predictors of poor long-term quality of life were current smoking, Canadian Cardiovascular Society grade III or IV, redo operation, female sex, diabetes, peripheral vascular disease, more than 2 days in intensive care, and chronic obstructive pulmonary disease. Twenty-five percent of patients with poor EQ-5D outcome had grade IV angina. Interestingly, age did not correlate with poor outcome, and administration of blood, arterial revascularization, left mainstem disease, or cross-clamp fibrillation had no impact on survival or outcome.

CONCLUSIONS

Coronary artery bypass grafting is associated with excellent 10-year survival and quality of life.

Acute and long-term survival in chronically critically ill surgical patients: a retrospective observational study

INTRODUCTION

Various cohort studies have shown that acute (short-term) mortality rates in unselected critically ill patients may have improved during the past 15 years. Whether these benefits also affect acute and long-term prognosis in chronically critically ill patients is unclear, as are determinants relevant to prognosis.

METHODS

We conducted a retrospective analysis of data collected from March 1993 to February 2005. A cohort of 390 consecutive surgical patients requiring intensive care therapy for more than 28 days was analyzed.

RESULTS

The intensive care unit (ICU) survival rate was 53.6%. Survival rates at one, three and five years were 61.8%, 44.7% and 37.0% among ICU survivors. After adjustment for relevant covariates, acute and long-term survival rates did not differ significantly between 1993 to 1999 and 1999 to 2005 intervals. Acute prognosis was determined by disease severity during ICU stay and by primary diagnosis. However, only the latter was independently associated with long-term prognosis. Advanced age was an independent prognostic determinant of poor short-term and long-term survival.

CONCLUSION

Acute and long-term prognosis in chronically critically ill surgical patients has remained unchanged throughout the past 12 years. After successful surgical intervention and intensive care, long-term outcome is reasonably good and is mainly determined by age and underlying disease.

Vasopressin, when added to norepinephrine, was not associated with increased predicted mortality after cardiac surgery

BACKGROUND AND AIMS

Arginin vasopressin (AVP) is a potent vasoconstrictor which has been used in vasodilatory shock when therapy with catecholamines and fluids has failed. In this study we evaluated the association of AVP with organ failure and mortality in cardiac surgical patients suffering from vasodilatory shock refractory to norepinephrine (NE) treatment.

MATERIAL AND METHODS

Cardiac surgical patients who received AVP in addition to NE (N=33, AVP-group) and 33 control patients (NE group) who were treated with an equal dose of NE compared with AVP patients when AVP infusion started. Data on preoperative risk factors according to EuroSCORE and predicted mortality calculated by logistic EuroSCORE were collected preoperatively. Data on hemodynamics, organ dysfunctions, length of intensive care unit stay and mortality were collected.

RESULTS

EuroSCORE did not differ between the groups, AVP:10.4 +/- 3.9 vs. NE 8.9 +/- 4.0. Observed 30 day mortality was lower than predicted in both groups, AVP: 7 (21.7%) vs. predicted mortality 25.9% and NE: 2 (6.1%) vs. 16.0%, respectively. There were more renal complications (36.4% vs. 9.1%, p = 0.008) and infections (30.3% vs. 3.0%, p = 0.003) in patients receiving AVP. Cardiovascular complications did not differ between the groups.

CONCLUSIONS

In this prospectively observed cohort of cardiac surgical patients, AVP did not increase mortality predicted by Euroscore. Anyhow renal and infection complications were common.

A comparative analysis of predictive models of morbidity in intensive care unit after cardiac surgery - part I: model planning

Background

Different methods have recently been proposed for predicting morbidity in intensive care units (ICU). The aim of the present study was to critically review a number of approaches for developing models capable of estimating the probability of morbidity in ICU after heart surgery. The study is divided into two parts. In this first part, popular models used to estimate the probability of class membership are grouped into distinct categories according to their underlying mathematical principles. Modelling techniques and intrinsic strengths and weaknesses of each model are analysed and discussed from a theoretical point of view, in consideration of clinical applications.

Methods

Models based on Bayes rule, k-nearest neighbour algorithm, logistic regression, scoring systems and artificial neural networks are investigated. Key issues for model design are described. The mathematical treatment of some aspects of model structure is also included for readers interested in developing models, though a full understanding of mathematical relationships is not necessary if the reader is only interested in perceiving the practical meaning of model assumptions, weaknesses and strengths from a user point of view.

Results

Scoring systems are very attractive due to their simplicity of use, although this may undermine their predictive capacity. Logistic regression models are trustworthy tools, although they suffer from the principal limitations of most regression procedures. Bayesian models seem to be a good compromise between complexity and predictive performance, but model recalibration is generally necessary. k-nearest neighbour may be a valid non parametric technique, though computational cost and the need for large data storage are major weaknesses of this approach. Artificial neural networks have intrinsic advantages with respect to common statistical models, though the training process may be problematical.

Conclusion

Knowledge of model assumptions and the theoretical strengths and weaknesses of different approaches are fundamental for designing models for estimating the probability of morbidity after heart surgery. However, a rational choice also requires evaluation and comparison of actual performances of locally-developed competitive models in the clinical scenario to obtain satisfactory agreement between local needs and model response. In the second part of this study the above predictive models will therefore be tested on real data acquired in a specialized ICU.

The use of artificial neural networks to stratify the length of stay of cardiac patients based on preoperative and initial postoperative factors

BACKGROUND

The limitations of current prognostic models in identifying postoperative cardiac patients at risk of experiencing morbidity and subsequently an extended intensive care unit length of stay (ICU LOS) is well recognized. This coupled with the desire for risk stratification in order to prioritize medical intervention has lead to the need for the development of a system that can accurately predict individual patient outcome based on both preoperative and immediate postoperative clinical factors. The usefulness of artificial neural networks (ANNs) as an outcome prediction tool in the critical care environment has been previously demonstrated for medical intensive care unit (ICU) patients and it is the aim of this study to apply this methodology to postoperative cardiac patients.

METHODS

A review of contemporary literature revealed 15 preoperative risk factors and 17 operative and postoperative variables that have a determining effect on LOS. An integrated, multi-functional software package was developed to automate the ANN development process. The efficacy of the resultant individual ANNs as well as groupings or ensembles of ANNs were measured by calculating sensitivity and specificity estimates as well as the area under the receiver operating curve (AUC) when the ANN is applied to an independent test dataset.

RESULTS

The individual ANN with the highest discriminating ability produced an AUC of 0.819. The use of the ensembles of networks technique significantly improved the classification accuracy. Consolidating the output of three ANNs improved the AUC to 0.90.

CONCLUSIONS

This study demonstrates the suitability of ANNs, in particular ensembles of ANNs, to outcome prediction tasks in postoperative cardiac patients.