Risk factors for nosocomial pneumonia after coronary artery bypass graft operations

The impact of chronic obstructive pulmonary disease on surgical outcomes after surgery for an acute abdominal diagnosis

PURPOSE

The current study was undertaken to describe the independent contribution of chronic obstructive pulmonary disease (COPD) to the risk of postoperative morbidity and in-hospital mortality among patients undergoing surgery for an acute abdominal diagnosis.

METHODS

Patients who underwent emergency abdominal procedures were identified from the electronic database of the Department of Visceral, Transplantation, Thoracic and Vascular Surgery of our institution. To evaluate differences in surgical risk associated with COPD, patients with COPD were matched for age, sex, and type of surgery with an equal number of controls who did not have COPD. Logistic regression was performed to evaluate the univariate and multivariate associations between the independent variables, including COPD and outcome variables.

RESULTS

Between January 2012 and December 2022, 3519 patients undergoing abdominal emergency surgery were identified in our abdominal surgical department. After removing ineligible cases, 201 COPD cases with an equal number of matched controls remained for analysis. The prevalence of COPD after the exclusion of ineligible cases was 5.7%. There were statistically significant differences in the rate of postoperative pulmonary complications (PPCs [57.7% vs. 35.8%; P < 0.001]), ventilator dependence (VD [63.2% vs. 46.3%; P < 0.001]), thromboembolic events (TEEs [22.9% vs. 12.9%; P = 0.009]), and in-hospital mortality (41.3% vs. 30.8%; P = 029) for patients with and without COPD. Independent of other covariates, the presence of COPD was not associated with a significantly increased risk of in-hospital mortality (OR, 1.16; 95% CI 0.70-1.97; P = 0.591) but was associated with an increased risk of PPCs (OR, 2.49; 95% CI 1.41-4.14; P = 0.002) and VD (OR, 2.26; 95% CI 1.22-4.17; P = 0.009).

CONCLUSIONS

Preexisting COPD may alter a patient's risk of PPCs and VD. However, it was not associated with an increased risk of in-hospital mortality.

Pulmonary Complications After Cardiac Surgery

Over the past two decades there has been a steady evolution in the practice of adult cardiac surgery with the introduction of “off-pump” surgery. However, respiratory complications remain a leading cause of postcardiac surgical morbidity and can prolong hospital stays and increase costs. The high incidence of pulmonary complications is in part due to the disruption of normal ventilatory function that is inherent to surgery in the thoracic region. Furthermore, patients undergoing such surgery often have underlying illnesses such as intrinsic lung disease (e.g., chronic obstructive pulmonary disease) and pulmonary dysfunction secondary to cardiac disease (e.g., congestive heart failure) that increase their susceptibility to postoperative respiratory problems. Given that many patients undergoing cardiac surgery are thus susceptiple to pulmonary complications, it is remarkable that more patients do not suffer from them during and after cardiac surgery. This is to a large degree because of advances in anesthetic, surgical and critical care that, for example, have reduced the physiological insults of surgery (e.g., better myocardial preservation techniques) and streamlined care in the immediate postoperative period (e.g., early extubation). Moreover, the development of minimally invasive surgery and nonbypass techniques are further evidence of the attempts at reducing the homeostatic disruptions of cardiac surgery. This review examines the available information on the incidences, consequences, and treatments of postcardiac surgery respiratory complications.

A Preoperative Risk Model for Postoperative Pneumonia After Coronary Artery Bypass Grafting

BACKGROUND

Postoperative pneumonia is the most prevalent of all hospital-acquired infections after isolated coronary artery bypass graft surgery (CABG). Accurate prediction of a patient's risk of this morbid complication is hindered by its low relative incidence. In an effort to support clinical decision making and quality improvement, we developed a preoperative prediction model for postoperative pneumonia after CABG.

METHODS

We undertook an observational study of 16,084 patients undergoing CABG between the third quarter of 2011 and the second quarter of 2014 across 33 institutions participating in the Michigan Society of Thoracic and Cardiovascular Surgeons Quality Collaborative. Variables related to patient demographics, medical history, admission status, comorbid disease, cardiac anatomy, and the institution performing the procedure were investigated. Logistic regression through forward stepwise selection (p < 0.05 threshold) was utilized to develop a risk prediction model for estimating the occurrence of pneumonia. Traditional methods were used to assess the model's performance.

RESULTS

Postoperative pneumonia occurred in 3.30% of patients. Multivariable analysis identified 17 preoperative factors, including demographics, laboratory values, comorbid disease, pulmonary and cardiac function, and operative status. The final model significantly predicted the occurrence of pneumonia, and performed well (C-statistic: 0.74). These findings were confirmed through sensitivity analyses by center and clinically important subgroups.

CONCLUSIONS

We identified 17 readily obtainable preoperative variables associated with postoperative pneumonia. This model may be used to provide individualized risk estimation and to identify opportunities to reduce a patient's preoperative risk of pneumonia through prehabilitation.

Associations of hospital characteristics with nosocomial pneumonia after cardiac surgery can impact on standardized infection rates

To identify hospital-level factors associated with post-cardiac surgical pneumonia for assessing their impact on standardized infection rates (SIRs), we studied 43 691 patients in a cardiac surgery registry (2001–2011) in 16 hospitals. In a logistic regression model for pneumonia following cardiac surgery, associations with hospital characteristics were quantified with adjustment for patient characteristics while allowing for clustering of patients by hospital. Pneumonia rates varied from 0·7% to 12·4% across hospitals. Seventy percent of variability in the pneumonia rate was attributable to differences in hospitals in their long-term rates with the remainder attributable to within-hospital differences in rates over time. After adjusting for patient characteristics, the pneumonia rate was found to be higher in hospitals with more registered nurses (RNs)/100 intensive-care unit (ICU) admissions [adjusted odds ratio (aOR) 1·2, P = 0·006] and more RNs/available ICU beds (aOR 1·4, P < 0·001). Other hospital characteristics had no significant association with pneumonia. SIRs calculated on the basis of patient characteristics alone differed substantially from the same rates calculated on the basis of patient characteristics and the hospital characteristic of RNs/100 ICU admissions. Since SIRs using patient case-mix information are important for comparing rates between hospitals, the additional allowance for hospital characteristics can impact significantly on how hospitals compare.

Pre-treatment before coronary artery bypass surgery improves post-operative outcomes in moderate chronic obstructive pulmonary disease patients

INTRODUCTION

Chronic obstructive pulmonary disease (COPD) has traditionally been recognised as a predictor of poorer early outcomes in patients undergoing coronary artery bypass grafting (CABG). The aim of this study was to analyse the impact of different COPD stages, as defined by the Global Initiative for Chronic Obstructive Lung Disease (GOLD) spirometric criteria, on the early surgical outcomes in patients undergoing primary isolated non-emergency CABG.

METHOD

Between January 2008 and April 2012, 1 737 consecutive patients underwent isolated CABG in the Department of Cardiovascular Surgery of Gulhane Military Academy of Medicine; 127 patients with the diagnosis of moderate-risk COPD were operated on. Only 104 patients with available pulmonary function tests and no missing data were included in the study. Two different treatment protocols had been used before and after 2010. Before 2010, no treatment was applied to patients with moderate COPD before the CABG procedure. After 2010, a pre-treatment protocol was initiated. Patients who had undergone surgery between 2008 and 2010 were placed in group 1 (no pre-treatment, n = 51) and patients who had undergone surgery between 2010 and 2012 comprised group 2 (pre-treatment group, n = 53). These two groups were compared according to the postoperative morbidity and mortality rates retrospectively, from medical reports.

RESULTS

The mean ages of the patients in both groups were 62.1 ± 7.6 and 64.5 ± 6.4 years, respectively. Thirty-nine of the patients in group 1 and 38 in group 2 were male. There were similar numbers of risk factors such as diabetes, hypertension, renal disease (two patients in each group), previous stroke and myocardial infarction in both groups. The mean ejection fractions of the patients were 53.3 ± 11.5% and 50.2 ± 10.8%, respectively. Mean EuroSCOREs of the patients were 5.5 ± 2.3 and 5.9 ± 2.5, respectively in the groups. The average numbers of the grafts were 3.1 ± 1.0 and 2.9 ± 0.9. Mean extubation times were 8.52 ± 1.3 hours in group 1 and 6.34 ± 1.0 hours in group 2. The numbers of patients who needed pharmacological inotropic support were 12 in group 1 and five in group 2. Duration of hospital stay of the patients was shorter in group 2. While there were 14 patients with post-operative atrial fibrillation (PAF) in group 1, the number of patients with PAF in group 2 was five. Whereas there were seven patients who had pleural effusions requiring drainage in group 1, there were only two in group 2. There were three mortalities in group 1, and one in group 2. There were no sternal infections and sternal dehiscences in either group.

CONCLUSION

Pre-treatment in moderate-risk COPD patients improved post-operative outcomes while decreasing adverse events and complications. Therefore for patients undergoing elective CABG, we recommend the use of medical treatment.

Long-Term Mortality After Pneumonia in Cardiac Surgery Patients

Background:

The role that intensive care unit (ICU)-acquired pneumonia plays in the long-term outcomes of cardiac surgery patients is not well known. This study examined the association of pneumonia with in-hospital mortality and long-term mortality after adult cardiac surgery.

Methods:

A total of 2750 patients admitted to our ICU after cardiac surgery from January 2003 to December 2009 are the basis for this observational study. Patients who developed ICU-acquired pneumonia were matched with patients without it in a 1:2 ratio. The matching criteria were age, urgent or scheduled surgery, surgical procedure, and the propensity score for pneumonia. Multiple regression analysis was used to find predictors of hospital mortality. The relationship between pneumonia and long-term survival was analyzed with Kaplan-Meier survival estimates and a risk-adjusted Cox proportional regression model for patients discharged alive from hospital.

Results:

Pneumonia was diagnosed in 32 (1.2%) patients and there were 19 cases per 1000 days of mechanical ventilation. Patients with pneumonia had a significantly higher hospital mortality rate (28% vs 6.2%, P = .003) and a higher mortality at the end of follow-up (53% vs 19%, P < .0001) than those without it. Regression analysis showed that pneumonia was a strong predictor of hospital mortality. Five-year survival was as follows: pneumonia, 62%; control, 81%; and cohort patients, 91%. The Cox model showed that, after adjusting for confounding factors, patients with pneumonia (hazard ratio = 3.96, 95% confidence interval [CI]: 1.41-11.14) had poorer long-term survival.

Conclusion:

Pneumonia remains a serious complication in patients operated for cardiac surgery and is associated with increased hospital mortality and reduced long-term survival.

Outcomes of minimally invasive valve surgery in patients with chronic obstructive pulmonary disease

OBJECTIVES

We hypothesize that minimally invasive valve surgery in patients with chronic obstructive pulmonary disease (COPD) is superior to the conventional median sternotomy approach.

METHODS

We retrospectively reviewed 2846 consecutive surgery performed at our institution between January 2005 and September 2010, and identified 165 patients with COPD who underwent isolated valve surgery. In-hospital mortality, composite complication rates, intensive care unit and total hospital length of stay of those who had undergone a minimally invasive approach were compared with a cohort that underwent a standard median sternotomy approach.

RESULTS

Of the 165 patients, 100 underwent a minimally invasive approach and 65 had a median sternotomy. Baseline characteristics did not differ between the two groups. The mean age was 71 ± 11 years for the minimally invasive group and 68 ± 12 years for the median sternotomy group, (P = 0.31). In-hospital mortality was 1 (1%) in the minimally invasive group and 3 (5%) in the median sternotomy group, P = 0.14. Composite postoperative complications were significantly reduced in the minimally invasive group (30 versus 54%, P = 0.002). The median intensive care unit length of stay was 47 h (IQR 40-70) versus 73 h (IQR 51-112), P < 0.001, and the median postoperative length of stay was 6 days (IQR 5-9) versus 9 days (IQR 7-13), P < 0.001, for the minimally invasive and the median sternotomy groups, respectively.

CONCLUSIONS

Minimally invasive valve surgery in patients with COPD is associated with excellent short-term results, and thus should be considered an option in these patients.

Predictors and Outcomes of Prolonged Ventilation after Coronary Artery Bypass Graft Surgery

This study investigated and compared the risk factors and outcomes of patients undergoing coronary artery bypass graft surgery with and without the occurrence of prolonged mechanical ventilation. Data in a cardiac surgery database were examined retrospectively. Data selected included any isolated coronary artery bypass graft surgery performed by the surgical group from August 2005 to June 2009. The resulting cohort included a total of 2933 patients which was comprised of 116 patients with a ventilation time of greater than 72 hours (prolonged ventilation) and 2817 patients with a ventilation time of 72 hours or less (no prolonged ventilation). Patients with a prolonged ventilation time were matched (1:3 ratio) to patients not requiring a prolonged ventilation time by year of surgery resulting in our study cohort of 464 patients. To generate the unadjusted risks of each factor, χ2 and t test analysis were performed. Logistic regression analysis was then used to investigate the adjusted risk between cases and controls and each of the significant variables. χ2 and t tests were conducted comparing cases and controls with the outcome variables. Patients undergoing coronary artery bypass graft that experienced a prolonged ventilation time (cases) were more likely female, had a New York Hospital Association functional class of III or IV, and had a longer perfusion time. There was no significant difference between cases and controls with diabetes, chronic obstructive pulmonary disease, left ventricular ejection fraction, or body mass index while controlling for all significant risk factors. Careful patient selection and preparation during preoperative evaluation may help identify patients at risk for prolonged mechanical ventilation and thus help prevent the added morbidity and mortality associated with it.

Preoperative pulmonary function and mortality after cardiac surgery

BACKGROUND

The aim of the study was to examine the relationship between preoperative pulmonary function and outcomes after cardiac surgery.

METHODS

We performed preoperative pulmonary function tests (PFTs) in 1,169 patients undergoing cardiac surgery at the Minneapolis Veterans Affairs Medical Center. Airway obstruction was defined as forced expiratory volume in 1 minute (FEV(1)) to forced vital capacity ratio <0.7.

RESULTS

Of the 1,169 patients, 483 (41%) had a prior history of chronic obstructive pulmonary disease (COPD). However, 178 patients with a history of COPD had no airway obstruction on PFT. Conversely, 186 patients without a COPD history had airway obstruction on PFT. Thus, PFT results helped reclassify the COPD status of 364 patients (31%). Operative mortality was 2% in patients with no or mild airway obstruction versus 6.7% in those with moderate or severe obstruction (ie, FEV(1) to forced vital capacity ratio <0.7 and FEV(1) <80% predicted). Postoperative mortality was higher (odds ratio 3.2, 95% CI 1.6-6.2, P = .001) in patients with moderate or severe airway obstruction and in patients with diffusing capacity of the lung for carbon monoxide <50% of predicted (odds ratio 4.9, 95% CI 2.3-10.8, P = .0001). Notably, mortality risk was 10x higher (95% CI 3.4-27.2, P = .0001) in patients with moderate or severe airway obstruction and diffusing capacity of the lung for carbon monoxide <50% of predicted.

CONCLUSIONS

These data show that PFT before cardiac surgery reclassifies the COPD status of a substantial number of patients and provides important prognostic information that the current risk estimate models do not capture.

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.

Postoperative outcome after coronary artery bypass grafting in chronic obstructive pulmonary disease

BACKGROUND

It is uncertain if the presence and severity of airflow obstruction in chronic obstructive pulmonary disease (COPD) is predictive of surgical morbidity and mortality after coronary artery bypass grafting (CABG).

METHODS

Retrospective study of patients who underwent CABG between 1998 and 2003 in a university-affiliated hospital for whom a preoperative spirometry was available. COPD was diagnosed in smokers or ex-smokers 50 years of age or older in the presence of irreversible airflow obstruction. Patients were divided into three groups depending on the spirometry: controls (forced expiratory volume in 1 s [FEV1] 80% or more, FEV1/forced vital capacity [FVC] greater than 0.7), mild to moderate COPD (FEV1 50% or more and FEV1/FVC 0.7 or less) and severe COPD (FEV1 less than 50% and FEV1/FVC 0.7 or less).

RESULTS

Among the 411 files studied, 322 (249 men, 68+/-8 years of age) were retained (controls, n=101; mild to moderate COPD, n=153; severe COPD, n=68). The mortality rate (3.0%, 2.6% and 0%, respectively) was comparable among the three groups. Patients with severe COPD had a slightly longer hospital stay than controls (mean difference 0.7+/-1.4 days, P<0.05). Pulmonary infections were more frequent in severe COPD (26.5%) compared with mild to moderate COPD (12.4%) and controls (12.9%), P<0.05. Atrial fibrillation tended to be more frequent in severe COPD than in the other two groups.

CONCLUSION

Mortality rate associated with CABG surgery is not influenced by the presence and severity of airflow obstruction in patients with COPD. The incidence of pulmonary infections and length of hospital stay were increased in patients with severe COPD.

Predictive factors for pneumonia onset after cardiac surgery in Rio de Janeiro, Brazil

OBJECTIVE

To develop a predictive system for the occurrence of nosocomial pneumonia in patients who had cardiac surgery performed.

DESIGN

Retrospective cohort study.Setting. Two cardiologic tertiary care hospitals in Rio de Janeiro, Brazil.

PATIENTS

Between June 2000 and August 2002, there were 1,158 consecutive patients who had complex heart surgery performed. Patients older than 18 years who survived the first 48 postoperative hours were included in the study. The occurrence of pneumonia was diagnosed through active surveillance by an infectious diseases specialist according to the following criteria: the presence of new infiltrate on a radiograph in association with purulent sputum and either fever or leukocytosis until day 10 after cardiac surgery. Predictive models were built on the basis of logistic regression analysis and classification and regression tree (CART) analysis. The original data set was divided randomly into 2 parts, one used to construct the models (ie, "test sample") and the other used for validation (ie, "validation sample").

RESULTS

The area under the receiver-operating characteristic (ROC) curve was 69% for the logistic regression model and 76% for the CART model. Considering a probability greater than 7% to be predictive of pneumonia for both models, sensitivity was higher for the logistic regression models, compared with the CART models (64% vs 56%). However, the CART models had a higher specificity (92% vs 70%) and global accuracy (90% vs 70%) than the logistic regression models. Both models showed good performance, based on the 2-graph ROC, considering that 84.6% and 84.3% of the predictions obtained by regression and CART analyses were regarded as valid.

CONCLUSION

Although our findings are preliminary, the predictive models we created showed fairly good specificity and fair sensitivity.

Nosocomial pneumonia in elderly patients following cardiac surgery

OBJECTIVE

To identify modifiable risk factors of nosocomial pneumonia (NP) in elderly patients post-cardiac surgery.

DESIGN

A case-control study.

SETTING

Post-operative intensive care unit of a tertiary-level university affiliated hospital.

SUBJECTS

Seventy three case-control pairs. Case patients referred to elderly patients who developed pneumonia post-cardiac surgery. Controls subjects were matched for age, gender, type of surgery, forced expiratory volume in 1s (FEV(1)), and ejection fraction.

MEASUREMENTS

Baseline sociodemograpahic information, Charlson Comorbidity Index score, intra- and post-operative data were collected. When suspected, the presence of NP was confirmed by quantitative culture of protected bronchoalveolar lavage fluid 10(3) colony forming unit/ml or positive blood/pleural fluid culture identical to that recovered from respiratory samples.

RESULTS

The incidence of NP in elderly post-heart surgery was 8.3%. The mean duration after heart surgery to the occurrence of pneumonia was 7.2+/-4.9 days. Four variables were found to be significantly related to the development of NP by multivariate analysis: Charlson Index >2 (adjusted odds ratio [AOR] 4.7; 95% confidence interval [CI], 1.9-11.4; P<0.001), reintubation (AOR 6.2; 95% CI, 1.1-36.1; P=0.04), transfusion 4 units of PRBC (AOR 2.8; 95% CI, 1.2-6.3; P=0.01), and the mean equivalent daily dose of morphine (AOR 4.6; 95% CI, 1.4-14.6; P=0.01).

CONCLUSIONS

Although there are limited effective measures to lessen the burden of comorbidities, avoiding reintubation, finding a substitute to allogenic blood transfusion, and improved assessment of pain management could reduce the rate of NP in the post-operative period of cardiac surgery in the elderly population.

Postoperative cardiopulmonary thoracic imaging

An appreciation of the normal postoperative changes and complications following cardiac surgical procedures is essential when interpreting postoperative imaging studies. This article focuses on both the normal postoperative appearances and the imaging of complications following common cardiac surgical procedures. Irrespective of the specific nature of the surgery, certain common complications may occur, either from the surgery itself,the use of cardiac bypass, or the patient's underlying cardiac disorder. Postoperative imaging after specific thoracic cardiovascular surgeries is also discussed.

Ventilator-associated pneumonia after heart surgery: a prospective analysis and the value of surveillance

OBJECTIVE

To determine the frequency, etiology, and risk factors of ventilator-associated pneumonia (VAP) and purulent tracheobronchitis (TBX) in patients who have undergone heart surgery. To study the predictive role of systematic surveillance cultures.

DESIGN

Prospective study.

SETTING

Heart surgery intensive care unit.

PATIENTS

Intubated heart surgical patients.

INTERVENTIONS

Systematic tracheal aspirate and protected brush catheter cultures of all intubated patients.

MEASUREMENTS AND MAIN RESULTS

Studied were the frequency of lower respiratory tract infection in ventilated patients and the role of surveillance cultures. The frequency of VAP was 7.87% (34.5 per 1,000 days of mechanical ventilation), and the criteria for purulent tracheobronchitis was fulfilled by 8.15% of patients (31.13 per 1,000 days of mechanical ventilation). After multivariate analysis, the variables independently associated with the development of respiratory tract infection were central nervous system disorder (relative risk [RR] = 4.7), ulcer disease (RR = 3.6), New York Heart Association score >/=3 (RR = 4), need for mechanical circulatory support (RR = 6.8), duration of mechanical ventilation >96 hrs (RR = 12.3), and reintubation (RR = 63.7). Mortality in our study was as follows: VAP patients, 57.1%; purulent tracheobronchitis patients, 20.7%; colonized patients, 11.5%; and noncolonized patients, 1.6%. Regular surveillance cultures were taken from all ventilated patients to assess the anticipative value of the cultures in predicting respiratory tract infection. A total of 1,626 respiratory surveillance samples were obtained. Surveillance cultures effectively predicted only one episode of VAP and one of tracheobronchitis.

CONCLUSIONS

Patients undergoing heart surgery have a high frequency of VAP. VAP is associated with a poor prognosis. In this study, surveillance cultures failed as an anticipative diagnostic method.

Liberation From Mechanical Ventilation Following Heart Surgery

The definition of ventilator dependency following heart surgery has evolved from a requirement for mechanical ventilation for more than 48 hours to less than 24 hours. Minimization of risk factors assessed in the preoperative period and improved surical and anesthetic techniques lead to improved and shortned postoperative courses and decreased hospital lengths of stay. The management of ventilator dependency following heart surgery should be approached from the perspective of pre-intensive care unit, intensive care unit, and post-intensive care unit Issues. A thorough understanding of risk factors for adverse postoperative morbidity and mortality leads to foused intraoperative and postoperative management aimed at improved quality of life following surgery. Minimizing preoprative risks and matching the postoperative state with criteria for the ideal candidate for early extubation improves outcome and minimizes requirements for mechanical ventilation in the postoperative period. In the event of prolonged requirements for mechanical ventilation, correcting impediments to weanng from mechanical ventilation provides the best circumtances to facilitate the process of rehabilitation and liberaion from mechanical ventilation.

Role of acid suppressants in intensive care medicine

Bleeding from stress-induced mucosal lesions continues to be a potential problem in critically ill patients, although its incidence has decreased dramatically over the past decade. Patients considered to be at risk are those with respiratory failure, coagulopathy, severe burns or tetraplegia. The most important cause of stress ulcer bleeding is tissue hypoxia. Provided that appropriate dosage regimens are administered, all agents approved for stress ulcer prophylaxis may reduce the incidence of overt as well as clinically important bleeding. However, the efficacy of stress ulcer prophylaxis does not correlate with the efficacy of gastric acid inhibition. Although numerous studies have demonstrated that an alkaline gastric juice is associated with gastric Gram-negative bacterial overgrowth, controversy remains over whether the pharmacological suppression of gastric acid in critically ill patients facilitates nosocomial pneumonia. The reasons for these divergent results are discussed, as is a possible association between gastric acid suppression and other systemic infections. Finally, several cost-effectiveness analyses performed over recent years have demonstrated that, in properly selected critically ill patients, stress ulcer prophylaxis is cost-effective.

Nosocomial pneumonia. Diagnostic and therapeutic considerations

Many patients with presumed nosocomial pneumonia probably have infiltrates on the chest radiograph, fever, and leukocytosis resulting from noninfectious causes. Because of the high mortality and morbidity associated with nosocomial pneumonias, however, most clinicians treat such patients with a 2-week empiric trial of antibiotics. Before therapy is initiated, the clinician should rule out other causes of pulmonary infiltrates, fever, and leukocytosis that mimic a nosocomial pneumonia (e.g., pre-existing interstitial lung disease, primary or metastatic lung carcinomas, pulmonary emboli, pulmonary drug reactions, pulmonary hemorrhage, collagen vascular disease affecting the lungs, or congestive heart failure). If these disorders can be eliminated from diagnostic consideration, a 2-week trial of empiric monotherapy is indicated. The clinician should treat cases of presumed nosocomial pneumonia as if P. aeruginosa were the pathogen. Although P. aeruginosa is not the most common cause of nosocomial pneumonia, it is the most virulent pulmonary pathogen associated with nosocomial pneumonia. Coverage directed against P. aeruginosa is effective against all other aerobic gram-negative bacillary pathogens causing hospital-acquired pneumonia. The clinician should select an antibiotic for empiric monotherapy that is highly effective against P. aeruginosa, has a good side-effect profile, has a low resistance potential, and is relatively inexpensive in terms of its cost to the institution. The preferred agents for empiric monotherapy for nosocomial pneumonia are cefepime, meropenem, and piperacillin. Single organisms are responsible for nosocomial pneumonia, not multiple pathogens. S. aureus rarely, if ever, causes nosocomial pneumonia but is mentioned frequently in studies based on cultures of respiratory tract secretions. S. aureus, unless accompanied by a necrotizing pneumonia with rapid cavitation within 72 hours, in the sputum indicates colonization rather than infection and should not be addressed therapeutically. Antibiotics associated with a high resistance potential should not be used as monotherapy or included in combination therapy regimens (i.e., ceftazidime, ciprofloxacin, imipenem, or gentamicin). Combination therapy is more expensive than monotherapy and is indicated only when P. aeruginosa is extremely likely, based on its characteristic clinical presentation, or is proved by tissue biopsy. Therapy should not be based on respiratory secretion cultures regardless of technique. Optimal combination regimens include cefepime or meropenem plus levofloxacin or piperacillin or aztreonam or amikacin. Nosocomial pneumonias usually are treated for 14 days. Lack of radiographic or clinical response to appropriate empiric nosocomial pneumonia monotherapy after 14 days suggests an alternate diagnosis. In these patients, a tissue biopsy specimen should be obtained to determine the cause of the persistence of pulmonary infiltrates unresponsive to appropriate antimicrobial therapy.

Pulmonary complications after coronary revascularization

Pulmonary complications are common after coronary artery bypass grafting. Identifying those individuals with increased risk of respiratory complications allows for appropriate preoperative intervention. The most commonly seen pulmonary complications include pleural effusion, hemothorax, atelectasis, pulmonary edema, diaphragmatic dysfunction, and pneumonia. Clinical features and appropriate management of these common problems are discussed.

Risk factors for nosocomial pneumonia in critically ill trauma patients

Nosocomial pneumonia is the most common pulmonary complication in trauma patients and the leading cause of death in nosocomial infections. A comprehensive review of pneumonia studies is provided. The Centers for Disease Control's nosocomial pneumonia pathogenesis model is reviewed and was used to guide the selection of risk factors evaluated in this study. The purposes of this research were to identify underlying dimensions (factors) of variables that increase the risk of nosocomial pneumonia and to identify predictors of nosocomial pneumonia in critically ill trauma patients.

Nosocomial pneumonia in patients undergoing heart surgery

OBJECTIVE

To determine the risk factors related to the presence of postsurgical nosocomial pneumonia (NP) in patients who had undergone cardiac surgery.

DESIGN

A case-control study.

SETTING

Postcardiac surgical intensive care unit at a university center.

PATIENTS

A total of 45 patients with NP and 90 control patients collected during a 4-yr period.

INTERVENTIONS

Pre-, intra-, and postoperative factors were collected and compared between two groups of patients (cases vs. controls) to determine their influence on the development of NP. The diagnosis of NP was always microbiologically confirmed as pulmonary specimen brush culture of > or =10(3) colony-forming units/mL or positive blood culture/pleural fluid culture by the growth of identical microorganisms isolated at the lung. For each patient diagnosed with NP, we selected control cases at a ratio of 1:2.

MEASUREMENTS AND MAIN RESULTS

The incidence of NP was 6.5%. Multivariate analysis found a probable association of the following variables with a greater risk for the development of NP: reintubation (adjusted odds ratio [AOR], 62.5; 95% confidence interval [CI], 8.1-480; p = .01); nasogastric tube (AOR, 19.7; 95% CI, 3.5-109; p = .01), transfusion of > or =4 units of blood derivatives (AOR, 12.8; 95% CI, 2-82; p = .01) and empirical treatment with broad-spectrum antibiotics (AOR, 6.6; 95% CI, 1.2-36.8; p = .02). Culture results showed 13.3% of the NP to be of polymicrobial origin, whereas 77.3% of the microorganisms isolated were Gram-negative bacteria. The mortality (51 vs. 6.7%, p < .01) and the length of stay in the intensive care unit (25+/-14.8 days vs. 5+/-5 days, p < .01) were both greater in patients with NP.

CONCLUSIONS

We conclude that the surgical risk factors, except the transfusion of blood derivatives, have little effect on the development of NP. Reintubation, nasogastric tubing, previous therapy with broad-spectrum antibiotics, and blood transfusion are factors most likely associated with NP acquisition.

Epidemiology of ventilator-acquired pneumonia based on protected bronchoscopic sampling

We performed a prospective observational cohort study of the epidemiology and etiology of nosocomial pneumonia in 358 medical ICU patients in two university-affiliated hospitals. Protected bronchoscopic techniques (protected specimen brush and bronchoalveolar lavage) were used for diagnosis to minimize misclassification. Risk factors for ventilator-associated pneumonia were identified using multiple logistic regression analysis. Twenty-eight cases of pneumonia occurred in 358 patients for a cumulative incidence of 7.8% and incidence rates of 12.5 cases per 1, 000 patient days and 20.5 cases per 1,000 ventilator days. Staphylococcus aureus, Streptococcus pneumoniae, Pseudomonas aeruginosa, and Hemophilus species made up 65% of isolates from the lower respiratory tract, whereas only 12.5% of isolates were enteric gram-negative bacilli. Daily surveillance cultures of the nares, oropharynx, trachea, and stomach demonstrated that tracheal colonization preceded ventilator-associated pneumonia in 93.5%, whereas gastric colonization preceded tracheal colonization for only four of 31 (13%) eventual pathogens. By multiple logistic regression, independent risk factors for ventilator- associated pneumonia were admission serum albumin <= 2.2 g/dl (odds ratio [OR] 5.9; 95% confidence interval [CI] 2.0-17.6; p = 0.0013), maximum positive end-expiratory pressure >= 7.5 cm H2O (OR, 4.6; 95% CI, 1.4 to 15.1; p = 0.012), absence of antibiotic therapy (OR, 6.7; 95% CI, 1.8 to 25.3; p = 0.0054), colonization of the upper respiratory tract by respiratory gram-negative bacilli (OR, 3.4; 95% CI, 1.1 to 10.1; p = 0.028), pack-years of smoking (OR, 2.3 for 50 pack-years; 95% CI, 1. 2 to 4.2; p = 0.012), and duration of mechanical ventilation (OR, 3. 4 for 14 d; 95% CI, 1.5 to 7.8; p = 0.0044). Several of these risk factors for ventilator-associated pneumonia appear amenable to intervention.

Ventilator-associated pneumonia

Mechanically ventilated patients are at a substantially higher risk for developing nosocomial pneumonia. Overall, there is a relatively constant 1&!TN!150;3% risk per day of developing pneumonia while receiving mechanical ventilation. The sensitivity and specificity of clinical criteria alone for diagnosis of ventilator-associated pneumonias (VAP) is low. Several techniques have been developed to sample and quantitate the lower respiratory tract to improve the diagnostic yield. Gram-negative bacillary pneumonias account for the majority of the VAP. Strategies for prevention of VAP such as use of sucralfate for stress ulcer prophylaxis and selective decontamination of the digestive tract have been the focus of many clinical studies. Cost-effective preventive measures are needed to combat the increasing antimicrobial resistance, growing population of immunocompromised patients and increasing number of mechanically ventilated patients.

Coronary artery bypass grafting in patients with COPD

OBJECTIVE

To more fully define the influence of COPD in patients undergoing coronary artery bypass grafting (CABG).

METHODS

One hundred ninety-one patients with COPD underwent CABG from March 1, 1995, to June 21, 1996. There were 129 male and 62 female patients. The mean age was 69 years (45 to 86 years). Patients with COPD were defined according to the Summit Database definition: requires therapy for the treatment of chronic pulmonary compromise or has an FEV1 <75% of predicted value.

RESULTS

Hospital mortality was 7%. Hospital morbidity was 50%. Statistically significant (p<0.05) morbidity included general pulmonary complications (12%) and atrial fibrillation (27%). Hospital mortality for COPD patients with postoperative pneumonia was 11%. Hospital mortality for patients with COPD receiving steroids was 19%. The hospital mortality for patients > or = 75 years of age was 17%. The combined mortality for patients with COPD who are > or = 75 years of age and receiving steroid therapy was 50%. The mean length of stay was 12 days. Late mortality was 1% at a mean of 1.5 years.

CONCLUSIONS

Hospital mortality in most patients with mild-to-moderate COPD undergoing CABG is similar to those without COPD. In the minority of patients with severe COPD who are receiving steroids and > 75 years, the hospital mortality is exceptionally high. These findings support CABG in patients with mild-to-moderate COPD. Nonsurgical therapy should be considered for elderly COPD patients with severe disease taking steroids.

Nosocomial pneumonia. Diagnosis and prevention

Ventilator-associated pneumonia (VAP) is an important complication in patients with respiratory failure who undergo endotracheal intubation and mechanical ventilation. VAP cannot be accurately diagnosed by clinical or radiographic criteria or culture of endotracheal aspirates; however, it can be accurately diagnosed by histopathologic examination of lung tissue, rapid cavitation of a pulmonary infiltrate, culture of empyema fluid, percutaneous lung needle aspiration, simultaneous recovery of the same microorganism from cultures of respiratory secretions, and blood and quantitative culture of lower respiratory tract secretions obtained by bronchoscopy. VAP can be prevented by proper decontamination and use of ventilatory support equipment, practice of proper nursing techniques during care of the mechanically ventilated patient, and use of face mask ventilation in selected patients.

Temporal relationship of complications after coronary artery bypass graft surgery: scheduling for safe discharge

The postoperative courses of 224 patients who left the operating room alive after coronary bypass surgery were followed to determine the time of onset of complications to determine when discharge is safe. A total of 155 complications occurred in 103 patients including 59 with supraventricular tachycardia, 17 with fever, and 9 to 11 with ventricular arrhythmias, cerebrovascular accidents, wound infection, or deep vein thrombosis. Pneumonia occurred in seven patients, and other complications occurred in five or fewer patients. Most initial complications (77.6%) occurred by day 5, and 89.3% of the patients with complications had their initial event before day 8. Hence it appears that it is safe to discharge patients on day 8 after coronary artery bypass graft surgery if they have not had a postoperative complication.

Evaluation of definitions and parameters for sepsis assessment in patients after cardiac surgery

In 110 patients undergoing elective heart surgery on extracorporeal circulation, various parameters were studied regarding the early assessment of septic complications. In a first step, the Elebute score definition for postoperative sepsis validated in general surgery patients (score > or = 12) could be confirmed in an extended form (> or = 12 on > or = 2 days) for cardiac surgery patients. According to this definition (overall classification accuracy for clinically defined sepsis-related mortality: 94%), septic complications occurred in 16 patients and were associated with a significantly worse prognosis than in non-septic patients (mortality 69% vs. 1%, p < 0.0001). In contrast, SIRS (best classification criterion: positive on > or = 3 days) displayed a lower specificity for clinically defined sepsis-related mortality, at least during the early postoperative course (accuracy: 67%). Based on the Elebute score classification, other more practicable parameters were investigated regarding their usefulness for an early sepsis risk assessment in post cardiac surgical patients. Five additional severity scores (APACHE II, MOF-Goris, HIS, SAPS, SSS) were comparable (ROC area: 0.94 to 0.96) and superior to plasma PMN-elastase and neopterin, haemodynamics and clinical parameters in predicting the risk for septic complications as early as by the first postoperative day.

Radiographic pulmonary abnormalities after different types of cardiac surgery

One aim of this study was to determine the incidence of new radiographic pulmonary abnormalities during hospitalization after cardiac surgery. Another aim was to determine if such abnormalities are more common among patients who had left internal mammary artery (LIMA) grafting. The predictive value of radiographic abnormalities for clinically important pulmonary morbidity was also determined. The anteroposterior chest radiographs of 152 patients obtained by portable equipment were evaluated to determine the incidence of new postoperative radiographic pulmonary abnormalities such as atelectasis, consolidation, infiltrate, and pleural effusion. Clinically important pulmonary morbidity was defined as a delay in tracheal extubation or discharge from the hospital because of a pulmonary reason. Among the 89 patients who had LIMA grafting and left pleurotomy, there was an 88% incidence of left-sided pulmonary abnormalities; a 73% incidence of left-sided atelectasis; and a 55% incidence of left-sided effusion. Among the 63 patients who had saphenous vein grafting only and/or valvular surgery, the respective incidences were 68%, 54%, and 35%, which were lower (P less than or equal to 0.05) than those in the patients who had LIMA grafting. There was no significant difference in abnormalities between the saphenous vein grafting and the valvular surgery groups. The 35% incidence of left-sided pleural effusion when LIMA grafting and pleurotomy were not performed was unexpectedly high. There was no association between radiographic abnormalities and age, the duration of cardiopulmonary bypass, and the duration of aortic occlusion, indicating that cardiopulmonary bypass was not a primary etiology of these radiographic abnormalities.(ABSTRACT TRUNCATED AT 250 WORDS)