The association of complication type with mortality and prolonged stay after cardiac surgery with cardiopulmonary bypass

Ventilator-associated pneumonia in patients undergoing major heart surgery: an incidence study in Europe

Introduction

Patients undergoing major heart surgery (MHS) represent a special subpopulation at risk for nosocomial infections. Postoperative infection is the main non-cardiac complication after MHS and has been clearly related to increased morbidity, use of hospital resources and mortality. Our aim was to determine the incidence, aetiology, risk factors and outcome of ventilator-associated pneumonia (VAP) in patients who have undergone MHS in Europe.

Methods

Our study was a prospective study of patients undergoing MHS in Europe who developed suspicion of VAP. During a one-month period, participating units submitted a protocol of all patients admitted to their units who had undergone MHS.

Results

Overall, 25 hospitals in eight different European countries participated in the study. The number of patients intervened for MHS was 986. Fifteen patients were excluded because of protocol violations. One or more nosocomial infections were detected in 43 (4.4%) patients. VAP was the most frequent nosocomial infection (2.1%; 13.9 episodes per 1000 days of mechanical ventilation). The microorganisms responsible for VAP in this study were: Enterobacteriaceae (45%), Pseudomonas aeruginosa (20%), methicillin-resistant Staphylococcus aureus (10%) and a range of other microorganisms. We identified the following significant independent risk factors for VAP: ascending aorta surgery (odds ratio (OR) = 6.22; 95% confidence interval (CI) = 1.69 to 22.89), number of blood units transfused (OR = 1.08 per unit transfused; 95% CI = 1.04 to 1.13) and need for re-intervention (OR = 6.65; 95% CI = 2.10 to 21.01). The median length of stay in the intensive care unit was significantly longer (P < 0.001) in patients with VAP than in patients without VAP (23 days versus 2 days). Death was significantly more frequent (P < 0.001) in patients with VAP (35% versus 2.3%).

Conclusions

Patients undergoing aortic surgery and those with complicated post-intervention courses, requiring multiple transfusions or re-intervention, constitute a high-risk group probably requiring more active preventive measures.

Intrathecal morphine plus general anesthesia in cardiac surgery: effects on pulmonary function, postoperative analgesia, and plasma morphine concentration

OBJECTIVES

To evaluate the effects of intrathecal morphine on pulmonary function, analgesia, and morphine plasma concentrations after cardiac surgery.

INTRODUCTION

Lung dysfunction increases morbidity and mortality after cardiac surgery. Regional analgesia may improve pulmonary outcomes by reducing pain, but the occurrence of this benefit remains controversial.

METHODS

Forty-two patients were randomized for general anesthesia (control group n=22) or 400 microg of intrathecal morphine followed by general anesthesia (morphine group n=20). Postoperative analgesia was accomplished with an intravenous, patient-controlled morphine pump. Blood gas measurements, forced vital capacity (FVC), forced expiratory volume (FEV), and FVC/FEV ratio were obtained preoperatively, as well as on the first and second postoperative days. Pain at rest, profound inspiration, amount of coughing, morphine solicitation, consumption, and plasma morphine concentration were evaluated for 36 hours postoperatively. Statistical analyses were performed using the repeated measures ANOVA or Mann-Whiney tests (*p<0.05).

RESULTS

Both groups experienced reduced FVC postoperatively (3.24 L to 1.38 L in control group; 2.72 L to 1.18 L in morphine group), with no significant decreases observed between groups. The two groups also exhibited similar results for FEV1 (p=0.085), FEV1/FVC (p=0.68) and PaO2/FiO2 ratio (p=0.08). The morphine group reported less pain intensity (evaluated using a visual numeric scale), especially when coughing (18 hours postoperatively: control group= 4.73 and morphine group= 1.80, p=0.001). Cumulative morphine consumption was reduced after 18 hours in the morphine group (control group= 20.14 and morphine group= 14.20 mg, p=0.037). The plasma morphine concentration was also reduced in the morphine group 24 hours after surgery (control group= 15.87 ng.mL-1 and morphine group= 4.08 ng.mL-1, p=0.029).

CONCLUSIONS

Intrathecal morphine administration did not significantly alter pulmonary function; however, it improved patient analgesia and reduced morphine consumption and morphine plasma concentration.

Effect of complications on mortality after coronary artery bypass grafting surgery: evidence from New York State

OBJECTIVE

Complications are associated with increased risk of death. The objective of this study is to quantify the increased odds of dying from complications after isolated coronary artery bypass grafting surgery.

METHODS

We conducted a retrospective cohort study using the New York State Coronary Artery Bypass Grafting Surgery Reporting System for all patients undergoing isolated coronary artery bypass grafting surgery in New York State who were discharged between 1997 and 1999 (51,750 patients; 2.20% mortality). We estimated the independent effect of individual postoperative complications on in-hospital mortality after controlling for patient clinical risk factors and demographics.

RESULTS

The mortality rate for patients without complication was 0.77% versus 16.1% for patients with complications (P < .001). After adjusting for preoperative risk factors, transmural myocardial infarction (adjusted odds ratio, 7.90; P < .001), respiratory failure (adjusted odds ratio, 6.02; P < .001), renal failure (adjusted odds ratio, 7.15; P < .001), and stroke within 24 hours (adjusted odds ratio, 4.09; P < .001) were the most strongly associated with mortality.

CONCLUSIONS

There is a strong association between postoperative complications and in-hospital mortality. Complications after isolated coronary artery bypass grafting surgery are associated with a 1.4- to 8-fold increase in the odds of death after adjusting for severity of disease and comorbidities. This information might prove valuable to hospitals in their efforts to design quality improvement initiatives and care protocols to improve mortality after coronary artery bypass grafting surgery.

Long-Term Outcome of Survivors of Prolonged Intensive Care Treatment After Cardiac Surgery

BACKGROUND

The relative impact of perioperative risk profile and postoperative complications on long-term outcome in cardiac surgical patients is currently unclear. The aim of this work was to assess the relative predictive value of the European System for Cardiac Operative Risk Evaluation (EuroSCORE) and Sequential Organ Failure Assessment (SOFA) on long-term event-free survival in this patient population.

METHODS

Preoperative and postoperative variables, EuroSCORE and SOFA, 30-day mortality, and long-term mortality or hospital admission for cardiovascular events were assessed in 115 consecutive cardiac surgical patients in whom multiorgan dysfunction syndrome developed postoperatively.

RESULTS

Mean age was 70 +/- 8 years, 41% were women, EuroSCORE averaged 7.87 +/- 3.99, and postoperative stay in the intensive care unit was 10.3 +/- 8.2 days. In-hospital 30-day mortality was 10.4% (n = 12). During 1998 person-months follow-up, 12 (11.6%) of 103 patients discharged alive died, and 46 (44.7%) met the combined end point of all-cause death or cardiovascular admission. By Cox multivariate analysis, maximum SOFA (hazard ratio [HR], 2.17; 95% confidence interval [CI], 1.34 to 3.51) and maximum cardiovascular score (HR, 2.35; 95% CI, 1.22 to 4.51) independently predicted all-cause mortality. EuroSCORE (HR, 1.33; 95% CI, 1.01 to 1.76), maximum cardiovascular score (HR 2.09; 95% CI 1.41 to 3.10), and maximum liver score (HR 2.67; 95% CI, 1.46 to 4.86) were independently associated with the combined end point.

CONCLUSIONS

High-risk cardiac surgical patients with postoperative multiorgan dysfunction syndrome show excess mortality and cardiovascular morbidity after hospital discharge. Combined preoperative and postoperative risk stratification identifies patients with the highest likelihood of death or early readmission.

Postoperative infections after major heart surgery and prevention of ventilator-associated pneumonia: a one-day European prevalence study (ESGNI-008)

Few data have been published on the prevalence of postoperative infection in patients undergoing major heart surgery (MHS). The degree of compliance with standard measures used to prevent them is unknown. This study assessed the prevalence of infections, particularly ventilator-associated pneumonia (VAP), in patients undergoing MHS in 42 institutions from 13 European countries. On the study day, there were 321 postoperative MHS patients, of whom 164 (51%) were mechanically ventilated. The overall prevalence of infection was 26.8%. Lower respiratory tract infections represented 57% of all the infections present on the study day. Other infections included intravenous-catheter-related bloodstream infections (2.8%), surgical site infections (2.2%), urinary tract infections (0.9%) and postoperative mediastinitis (0.9%). Of the mechanically ventilated patients, 55 (33.5%) were not being nursed in a semi-recumbent position, 36 (22%) had heat-moisture exchangers with no antibacterial filters, and intracuff pressure was not monitored in 78 patients (47.6%). Only 13 patients (8%) were given continuous subglottic suctioning, 64 patients (39%) did not receive postural oscillation, and gastric overdistension was not actively prevented in 23 patients (14%). In conclusion, these data from intensive care units across Europe provide information on postoperative infections in an important subset of the patient population, and stress the need for active interventions to prevent VAP in patients undergoing MHS.

Infections following major heart surgery in European intensive care units: there is room for improvement (ESGNI 007 Study)

Patients undergoing major heart surgery (MHS) may be at increased risk for nosocomial infections. To assess the incidence and type of infections in MHS patients in European intensive care units (ICUs) and their quality of care, a questionnaire was sent to a selection of MHS ICUs in Europe. Seventeen hospitals from seven European countries participated. Overall, 53% of the ICUs received patients only for MHS and the other 47% were mixed. During the study period, 11 915 patients underwent MHS and 1181 (9.9%) developed one or more nosocomial infections. Ventilator-associated pneumonia (VAP) was the most common infection [median 3.8%; interquartile range (IQR) 1.8-4.9], followed by surgical wound infection (median 1.6%; IQR 0.8-2.3), catheter-related bloodstream infection (median 1.3%; IQR 0.8-2.1), mediastinitis (median 1.1%; IQR 0.4-1.6), urinary tract infection (median 0.6; IQR 0.4-1.4) and nosocomial endocarditis (median 0.2%; IQR 0.0-0.9). Median mortality was 4.7% (IQR 2.7-8.4) and median infection-related mortality was 1% (IQR 0.5-2.7). Regarding VAP, 18% of the ICUs did not routinely pursue a diagnosis. Microbiological information was quantitative in 35% of cases and exclusively qualitative in 65% of cases. An infectious disease specialist was regularly involved in VAP management in only 35% of the ICUs, and the therapeutic approach to VAP involved de-escalation in 59% of the ICUs. MHS ICUs in Europe still have a high rate of postoperative infections. Well-recognized routine practices for the diagnosis and treatment of VAP are not implemented regularly in many European institutions.

Preoperative anti-PF4/heparin antibody level predicts adverse outcome after cardiac surgery

OBJECTIVE

Preexisting serum antibodies to heparin/platelet factor 4 complexes may predispose adult cardiac surgical patients to increased perioperative morbidity and mortality. We sought to determine the association between preoperative serum antibodies directed against platelet factor 4/heparin complexes and major complications (in-hospital death or length of stay >10 days) in adult cardiac surgical patients.

METHODS

In a prospective observational study of 466 patients undergoing elective coronary artery bypass grafting, valvular heart surgery, or both, preoperative serum was assayed for anti-platelet factor 4/heparin antibody by using a commercially available enzyme-linked immunosorbent assay (Asserachrom HPIA). Known preoperative risk factors were assessed, and patients were assigned a risk score by using the validated method of Parsonnet and colleagues.

RESULTS

Major complications (death or postoperative hospitalization >10 days) occurred in 108 patients (23%). Overall, 59 (13%) patients had a positive preoperative anti-platelet factor 4/heparin antibody screen (upper limit of normal is 0.5 optical density units). A positive assay result independently predicted an increased risk of major complications (P = .0284; odds ratio, 1.98; 95% confidence interval, 1.06-3.62) over and above the effect of the Parsonnet risk score (P < .001; odds ratio, 1.07; 95% confidence interval, 1.05-1.10). The level of preoperative anti-platelet factor 4/heparin antibody was also significantly associated with major complications (P = .036; odds ratio, 1.31; 95% confidence interval, 1.02-1.68) independently of the Parsonnet risk score. No association (P > .75) existed between the Parsonnet risk score and preoperative anti-platelet factor 4/heparin antibody level.

CONCLUSIONS

Serum antibodies directed against platelet factor 4/heparin complexes are prevalent in the adult patient population undergoing cardiac surgery. The presence of these antibodies before surgery is an independent predictor for death or prolonged hospitalization after adult cardiac surgery.

Major Clinical Outcomes in Adults Undergoing Thoracic Aortic Surgery Requiring Deep Hypothermic Circulatory Arrest: Quantification of Organ-Based Perioperative Outcome and Detection of Opportunities for Perioperative Intervention

OBJECTIVE

The purpose of this study was to describe clinical outcome after adult thoracic aortic surgery requiring standardized deep hypothermic circulatory arrest (DHCA), to determine mortality and length of stay, neurologic outcome, cardiorespiratory outcome, and hemostatic and renal outcome after DHCA.

DESIGN

Retrospective and observational.

SETTING

Cardiothoracic operating rooms and intensive care unit (ICU).

PARTICIPANTS

All adults requiring thoracic aortic repair with DHCA.

INTERVENTIONS

None. The study was observational.

MAIN RESULTS

The cohort size was 110. All patients received an antifibrinolytic. The mortality rate was 8.2%. The mean length of stay was 6.8 days (ICU) and 14.0 days (hospital). The incidence of stroke was 8.1% and postoperative delirium was 10.9%. The rate of postoperative atrial fibrillation was 43.6%; 19.1% required postoperative mechanical ventilation longer than 72 hours. Chest tube drainage was 931 mL for the first 24 hours. Postoperative dialysis was required in 1.8% of patients. Renal dysfunction occurred in 40% to 50% of patients, depending on the definition.

CONCLUSIONS

The protocol for DHCA at the authors' institution is associated with superior or equivalent perioperative outcomes to those reported in the literature. This study identified the need for further quantification of the clinical outcomes after DHCA in order to prioritize outcome-based hypothesis-driven prospective intervention in DHCA.

Influence of renal dysfunction on mortality after cardiac surgery: modifying effect of preoperative renal function

BACKGROUND

Acute renal failure (ARF) requiring dialysis is an independent risk factor of mortality after cardiac surgery; the level of preoperative renal function influences the risk of both postoperative ARF and mortality. The relationship between mild renal dysfunction and mortality, and the modifying effect of baseline renal function on this association, is less clear.

METHODS

We studied 31,677 patients undergoing cardiac surgery between 1993 and 2002. We used a logistic regression model to assess the relationship between postoperative renal dysfunction and mortality, while adjusting for preoperative renal function, postoperative ARF requiring dialysis, and other risk factors.

RESULTS

The overall postoperative mortality rate was 2.2% (698/31,677). For the entire cohort, a clinically relevant increase in the adjusted risk of mortality occurred beyond 30% decline in postoperative GFR. The mortality rate was 5.9% (N, 292/4986) among patients who developed 30% or greater decline in postoperative GFR not requiring dialysis versus 0.4% (N, 106/26,136) among those with <30% decline (P < 0.001). A significant interaction between preoperative GFR and percent change in postoperative GFR (P < 0.001) indicated that at equivalent degrees of renal dysfunction, the mortality risk was greater at a lower preoperative GFR. ARF requiring dialysis was strongly associated with mortality in the model (odds ratio 4.2; 95% CI 3.1-5.7).

CONCLUSION

Renal dysfunction not requiring dialysis is an independent risk factor of mortality after cardiac surgery. A better preoperative GFR attenuates the effect of postoperative renal dysfunction on mortality; this interaction needs to be considered while defining a clinically relevant threshold of ARF.

Randomised controlled trial assessing the impact of a nurse delivered, flow monitored protocol for optimisation of circulatory status after cardiac surgery

OBJECTIVE

To assess whether a nurse led, flow monitored protocol for optimising circulatory status in patients after cardiac surgery reduces complications and shortens stay in intensive care and hospital.

DESIGN

Randomised controlled trial.

SETTING

Intensive care unit and cardiothoracic unit of a university teaching hospital.

PARTICIPANTS

174 patients who underwent cardiac surgery between April 2000 and January 2003.

INTERVENTIONS

Patients were allocated to conventional haemodynamic management or to an algorithm guided by oesophageal Doppler flowmetry to maintain a stroke index above 35 ml/m2.

RESULTS

26 control patients had postoperative complications (two deaths) compared with 17 (four deaths) protocol patients (P = 0.08). Duration of hospital stay in the protocol group was significantly reduced from a median of nine (interquartile range 7-12) days to seven (7-10) days (P = 0.02). The mean duration of hospital stay was reduced from 13.9 to 11.4 days, a saving in hospital bed days of 18% (95% confidence interval -12% to 47%). Usage of intensive care beds was reduced by 23% (-8% to 59%).

CONCLUSION

A nurse delivered protocol for optimising circulatory status in the early postoperative period after cardiac surgery may significantly shorten hospital stay.