Pneumonia in the surgical patient

[Postoperative complications after major lung resection]

INTRODUCTION

The advent of the minimally invasive techniques has allowed an expansion of the indications for thoracic surgery, particularly in older patients and those with more comorbidities. However, the rate of postoperative complications has remained stable.

STATE OF THE ART

Postoperative complications are defined as any variation from the normal course. They occur in 30% but majority of them are minor. The 30-day mortality rate for lung resection varies range between 2 % and 3% in the literature. Complications can be classified as: (1) early (occurring in the first 24hours) including both "generic" surgical complications (especially postoperative bleeding) and complications more specific to lung surgery (Acute respiratory syndrome, atelectasis); (2) in-hospital complications and those occurring during the first 3 months; these are dominated by infectious events in particular pneumonia but also bronchial (bronchopleural fistula), pleural (pneumothorax, hydrothorax) or cardiac complications; (3) late complications are dominated by chronic pain, affecting 60% of patients having a thoracotomy at three months. Lobectomy is the most common lung resection. Pneumonectomy is a distinct procedure requiring a specific peri- and postoperative management. Right pneumonectomy is associated with a higher risk with a treatment related-mortality ranging between 7 and 10%.

CONCLUSION

Major lung resection has benefited from minimally invasive approaches and fast track to surgery. However, it is important to note the occurrence of new and specific complications related to those news surgical access.

A Retrospective Study of Nosocomial Pneumonia in Postoperative Patients Shows a Higher Mortality Rate in Patients Receiving Nasogastric Tube Feeding

Pneumonia remains a significant cause of morbidity and mortality in surgical patients. Though most studies have focused on pneumonia in trauma or special respiratory intensive care units (ICU), we examine postoperative ventilator-associated pneumonia in patients undergoing elective operations. We hypothesized that a study of multiple clinical variables would disclose factors influencing morbidity and mortality in these patients. We conducted a retrospective review of 1969 patients who underwent elective general, cardiac, and general thoracic procedures during a 6-month period in a private teaching hospital. A total of 77 patients (3.9%) developed postoperative ventilator-associated pneumonia. Thirty-eight (49%) patients had a history of smoking and 27 (35%) had chronic obstructive pulmonary disease (COPD). Among these 77 patients, 20 (26%) experienced recurrent pneumonia. The overall mortality rate for patients developing pneumonia was 34 per cent. At diagnosis of pneumonia, 33 patients were receiving enteral nutrition through nasogastric feeding tubes, whereas 41 received no enteral feeding. The method of nutritional intake was not known in 3 patients. The feeding/nonfeeding groups were similar in age and underlying disease, differing significantly only in the higher number of smokers in the patients not receiving enteral nutrition ( P = 0.03). To our surprise, the mortality rate from all causes was higher ( P = 0.018) in the patients who received tube feedings through soft, nasogastric feedings (33%) than in those not enterally fed (17%). Parenteral nutrition, COPD, number of ventilator days, and the location of the tip of the feeding tube did not correlate with mortality. The mortality rate from all causes was higher in patients with postoperative pneumonia who received tube feedings, despite similar underlying medical illnesses. Enteral feeding of postoperative surgical patients has many desirable effects, but prospective studies should address harmful effects, such as presumed aspiration and related pneumonia.

Correlation of Bronchoalveolar Lavage with Radiographic Evidence of Pneumonia in Thermally Injured Children

The diagnosis of pneumonia in the critically ill patient is very difficult because the usual signs and symptoms are unreliable in the intensive care setting. Bronchoalveolar lavage (BAL) is a diagnostic tool with a reported sensitivity of 70%. The purpose of this study was to determine the efficacy and specificity of BAL in severely burned pediatric patients. An analysis was performed in which BAL cultures were compared and correlated to chest radiographs. Patient characteristics, such as age, sex, burn size, depth of burn, and the presence of inhalation injury were evaluated. Over a period of 18 months, 58 thermally injured children were identified who underwent 101 BALs. The mean age was 6.5 +/- 5 years, mean TBSA was 39 +/- 27%, and inhalation injury was diagnosed in 20 patients (35%). Of 101 BALs, 48 were positive, and of the 101 chest radiographs, 20 demonstrated signs of pneumonia. Ten of those were associated with a positive BAL and 10 with a negative BAL. Thus, the positive predictive value of BAL was 21%, whereas the negative predictive value was 81%. Interestingly 80% of patients with tracheobronchitis from inhalation injury demonstrated a positive BAL. We conclude that in pediatric burn patients BAL correlates poorly with radiographic signs of pneumonia.

Pathogenesis of posttraumatic empyema: the impact of pneumonia on pleural space infections

BACKGROUND

Thoracic empyema may result either from primary pneumonic sources or intraabdominal sources of infection that seed the pleural space secondarily. In patients with thoracostomy tubes, empyema may result when blood in the pleural space becomes contaminated during tube insertion. To elucidate the cause of posttraumatic empyema, preoperative bronchoalveolar lavage (BAL)/sputum cultures obtained from patients with posttraumatic empyema were compared with cultures obtained at the time of decortication.

MATERIALS AND METHODS

A retrospective study was conducted of trauma patients who developed empyema and underwent either video-assisted thoracoscopy or thoracotomy with decortication following blunt or penetrating trauma. At our level I trauma center, we studied all empyema cases diagnosed from November, 1998 to July, 2001. Data collection included patient demographics, injuries sustained, preoperative BAL/sputum cultures, and culture data obtained at the time of decortication. All BAL/sputum cultures were performed no more than 5 days prior to decortication.

RESULTS

Thirty-seven patients (26 blunt/11 penetrating) were identified. No patients had concurrent intra-abdominal sources of infection. All patients had at least one chest tube placed prior to decortication. Preoperative respiratory cultures (BAL/sputum) were obtained in 34 patients. The most common organisms isolated were Staphylococcus aureus in six patients (18%) and Hemophilus influenzae in six patients (18%). Intraoperative cultures were obtained in all 37 patients, with the most common organism being S. aureus isolated in 22 patients (60%). Interestingly, a correlation between preoperative BAL/sputum and intraoperative cultures was found in only seven of the 34 patients (21%) who had concomitant respiratory and pleural cultures. Cultures positive for S. aureus were isolated from five patients, Streptococcus pneumoniae from one patient, and Pseudomonas aeruginosa from one patient.

CONCLUSION

Little correlation existed between preoperative BAL/sputum cultures and intraoperative cultures in this series of patients with posttraumatic empyema. This suggests that the causation is most often not a parapneumonic process. Furthermore, since S. aureus was the most common organism recovered from empyema, the source was more likely from inoculation of the pleural space by the injury itself or by tube thoracostomy.

Emergence of resistant microbes in critical care units is transient, despite an unrestricted formulary and multiple antibiotic trials

BACKGROUND

Antimicrobial resistance is a growing problem in the intensive care setting. This study was designed to evaluate the trends in bacterial prevalence and changes in antibiotic resistance at a large university hospital over the past decade. Antimicrobial resistance data were compared among the surgical intensive care unit (SICU), medical intensive care unit (MICU), and burn unit (BNU).

MATERIALS AND METHODS

A large database was created using hospital-wide data from 1989 to 2000. A retrospective analysis of the evolution of organism prevalence, antibiotic resistance, and response to study protocols was evaluated. The formulary was relatively unrestricted. All positive cultures were examined, focusing on wound, blood, and sputum cultures. Six primary antibiotics were targeted specifically to follow resistance patterns.

RESULTS

There were 847 identified positive wound cultures, 2,862 positive sputum cultures, and 2,252 positive blood cultures. The incidence of gram-positive and gram-negative organisms changed little in the SICU and BNU; however, there was a large increase in gram-positive organisms and yeast in the MICU over the past 5 years. Anaerobic bacteria and yeast were nearly nonexistent pathogens in the SICU and BNU. The resistance pattern of most organisms changed little following the introduction of a new antibiotic. However, the effectiveness of study antibiotics after formal clinical study periods decreased dramatically, albeit transiently.

CONCLUSION

Hospital-wide antibiotic resistance data may be misleading and may not reflect individual critical care units throughout the hospital. Bacterial flora, including resistant organisms, changed little over 10 years, despite an unrestricted formulary. The emergence of resistant and opportunistic organisms is related to antibiotic usage and can vary significantly over time. This suggests that a policy of administering limited duration, narrow spectrum antibiotics may reduce drug resistance.

Nosocomial Pneumonia is Not Prevented by Protective Contact Isolation in the Surgical Intensive Care Unit

Nosocomial pneumonia (NP) is the leading cause of death from hospital-acquired infection in intubated surgical intensive care unit (SICU) patients. To determine whether protective contact isolation would lower the incidence of NP in intubated patients we performed a prospective, randomized, and controlled study in two SICUs in a tertiary medical center. Over a period of 15 months two identical ten-bed SICUs alternated for 3-month periods between protective contact isolation (isolation group) and standard “universal precautions” (control group). In the isolation group all personnel and visitors donned disposable gowns and nonsterile gloves before entering an intubated patient's room; handwashing was required before entry and on leaving the room. In the control group caregivers utilized only “standard precautions” including handwashing and nonsterile gloves for intubated patients. Respiratory cultures were obtained 48 hours after SICU admission and every 48 hours thereafter until extubation, transfer to floor care, or death. Airway colonization (AC) occurred in 72.7 per cent of isolated patients and 69.0 per cent of control patients ( P = 0.61). The incidence of NP was significantly higher in the isolation group (36.4%) compared with the control group (19.5%) ( P = 0.02). There was no statistically significant difference between groups in days from SICU admission to AC, days to NP, and mortality. We conclude that protective contact isolation with gowns, gloves, and handwashing is not superior to gloves and handwashing alone in the prevention of AC and NP in SICU patients and may in fact be detrimental.

Postoperative nosocomial pneumonia: nurse-sensitive interventions

Nosocomial pneumonia (NP) is well documented as the second most common nosocomial infection. It is now more common in surgical patients than surgical-site or wound infection. Healthcare implications of NP include not only increased patient morbidity and mortality, but also increased use of healthcare resources. The advanced practice nurse plays an integral role in the prevention and minimization of NP across healthcare settings. This article focuses on postoperative NP after abdominal, cardiac, or thoracic surgery in the non-mechanically ventilated patient and discusses the diagnostic assessment, risk factors, and potential nurse-sensitive interventions to prevent or minimize this complication. Ideas for potential nursing research related to these risk factors are described.

Early elevation of soluble CD14 may help identify trauma patients at high risk for infection

BACKGROUND

Elevated levels of soluble CD14 (sCD14) have been implicated in both gram-positive and gram-negative sepsis, and it has been associated with high mortality in trauma patients who become infected.

METHODS

Eleven healthy volunteers and 25 adult trauma patients with multiple injuries and a mean Injury Severity Score of 32 participated. Whole blood was obtained at intervals. Immunohistochemistry was used to quantify membrane CD14 (mCD14), by flow cytometry and plasma levels of sCD14 by enzyme-linked immunosorbent assay. Analysis of variance and Student's T test with Mann-Whitney posttest were used to determine significance at p < 0.05.

RESULTS

On posttrauma day 1, sCD14 was significantly different in the plasma of infected patients compared with normal controls (7.16 +/- 1.87 microg/mL vs. 4.4 +/- 0.92 microg/mL, p < 0.01), but not significantly different from noninfected patients. The percentage of monocytes expressing mCD14 in trauma patients did not differentiate them from normal controls; however, mCD14 receptor density did demonstrate significance in septic trauma patients (n = 15) versus normal controls on posttrauma day 3 (p = 0.0065).

CONCLUSION

On the basis of our data, mCD14 did not differentiate infected and noninfected trauma patients, although trauma in general reduced mCD14 and elevated sCD14. Interestingly, 100% of patients who exceeded plasma levels of 8 microg/mL of sCD14 on day 1 after injury developed infections. Therefore, early high expressers of sCD14 may be at higher risk for infectious complications after trauma.

Endotoxin and muramyl dipeptide modulate surface receptor expression on human mononuclear cells

Endotoxin (lipopolysaccharide (LPS), 100 ng/ml) and muramyl dipeptide (MDP 100 ng/ml), two immunomodulatory bacterial cell wall products, were incubated with human whole blood, and the expression of receptors involved in antigen presentation, costimulation, and cell activation was investigated by use of flow cytometry. On monocytes, LPS and MDP increased surface expression of human leukocyte antigen-DR (HLA-DR), CD18, CD54 (intercellular adhesion molecule-1, ICAM-1), and CD86 (B7-2). On lymphocytes, LPS but not MDP increased HLA-DR expression after 18 h. The expression of CD28, CD49d/CD29, and CD106 (vascular cell adhesion molecule-1, VCAM-1) remained unchanged on both monocytes and lymphocytes. The early increase (1-6 h) of CD18 and ICAM-1 expression led us to hypothesize that CD18-dependent costimulatory signals were involved in the later (6 h) increase of monocyte HLA-DR expression. However, blocking studies using monoclonal antibodies against CD18 (IB4, 15 microg/ml) demonstrated that the LPS- and MDP-induced increase of HLA-DR and ICAM-1 expression on monocytes was not mediated through CD18. LPS induced the expression of the early activation marker CD69 by a CD14-dependent but CD18-independent mechanism, whereas MDP did not induce CD69 expression. Analysis of leukocyte subsets demonstrated that CD4(+) T-cells, CD8(+) T-cell, CD19(+) B-cells, CD56(+) natural killer (NK)-cells, and CD14(+) monocytes increased the expression of CD69 after stimulation with LPS. Collectively, these data demonstrate a stronger immunomodulatory effect of LPS compared with MDP which may, in part, explain the established difference of toxicity between these two bacterial cell wall products.

Single versus combination antimicrobial therapy for ventilator-associated pneumonia

The appropriate selection of definitive antimicrobial therapy is a necessary component of the overall treatment for ventilator-associated pneumonia. When possible, single-agent therapy is preferable. A combination of antibiotics is necessary to treat multiple organisms not susceptible to a single appropriate antibiotic and when antibiotic-resistant gram-negative bacteria are present. Treatment failure is more commonly the result of persistent pneumonia and the development of antibiotic resistance than to recurrence after successful antimicrobial therapy. The duration of treatment will vary depending on the severity of the underlying illness and the pneumonic process.

Heparin and enoxaparin enhance endotoxin-induced tumor necrosis factor-alpha production in human monocytes

OBJECTIVE

To determine whether heparin or the low-molecular-weight heparin enoxaparin alter lipopolysaccharide (LPS)-induced monocyte activation.

SUMMARY BACKGROUND DATA

Heparin is widely used in clinical practice to inhibit the coagulation cascade. However, heparin also is a naturally occurring glucosaminoglycan and a pleiotropic immunomodulator that binds to a variety of proteins. LPS is a component of gram-negative bacteria and is thought to be responsible for many of the deleterious effects seen in sepsis. The binding of LPS to CD14 induces a signaling cascade that results in the release of many inflammatory mediators, including tumor necrosis factor-alpha (TNF-alpha).

METHODS

Monocytes from healthy volunteers were isolated and cultured in the presence of saline, LPS (10 ng/ml), heparin (0.1 to 1000 microg/ml), or enoxaparin (0.1 to 1000 microg/ml). In blocking experiments, cells were pretreated for 60 minutes with the monoclonal anti-CD14 antibody MY4 (10 microg/ml) or with isotype-matched control IgG2 (10 microg/ml). TNF-alpha values were measured with enzyme-linked immunosorbent assay. Significance was assessed with analysis of variance.

RESULTS

Heparin (10 to 1000 microg/ml) and enoxaparin (1000 microg/ml) significantly enhanced LPS-induced TNF-alpha release. Heparin (1000 microg/ml) or enoxaparin (1000 microg/ml) did not produce TNF-alpha in the absence of LPS. Blockade of CD14 abrogated both LPS-induced TNF-alpha release and the effect of heparin or enoxaparin to enhance LPS-induced TNF-alpha release.

CONCLUSIONS

The effect of heparin to enhance LPS-induced TNF-alpha release is a biologic phenomenon that reveals a novel and potentially important host defense mechanism during endotoxemia and sepsis. Binding of LPS to CD14 is necessary to induce this phenomenon, suggesting that both heparin and enoxaparin induce signaling mechanisms that are downstream from the initial binding of LPS on CD14.

Endocytosis of Heparin-Binding Protein (CAP37) Is Essential for the Enhancement of Lipopolysaccharide-Induced TNF-α Production in Human Monocytes

Heparin-binding protein (HBP), also known as CAP37, is a proteolytically inactive serine protease homologue that is released from activated granulocytes. However, HBP is not a biologically inactive molecule but rather a multifunctional protein with properties that include the enhancement of LPS-induced TNF-α production from monocytes. We have previously demonstrated that HBP is internalized in monocytes. In the current study, we hypothesize that HBP is internalized in monocytes via endocytosis, and this internalization is an important mechanism by which HBP enhances LPS-induced TNF-α release. Using whole blood from healthy donors and flow cytometry, we found that colchicine (0.1–10 mM), cytochalasin D (1000 μM), NH4Cl (10–50 mM), and bafilomycin A1 (0.1–3 μM) significantly reduced the affinity of FITC-HBP for CD14-positive monocytes. Using isolated human monocytes and ELISA, we found that colchicine (0.1 mM), cytochalasin D (30 and 300 μM), NH4Cl (30 mM), and bafilomycin A1 (1 μM) significantly reduced the effect of HBP (10 μg/ml) to enhance LPS (10 ng/ml)-induced TNF-α release after 24 h. These findings demonstrate that internalization of HBP in monocytes is essential for the enhancement of LPS-induced TNF-α release. Transport of HBP to an activating compartment depends on intact F-actin polymerization and endosomal acidification, an important mechanism for endosomal protein sorting and trafficking.

Validation of a predictive model for postoperative pulmonary complications

OBJECTIVE

To test or validate a previously reported model for predicting postoperative pulmonary complications (PPCs) after elective abdominal surgical procedures.

DESIGN

Prospective, descriptive.

SETTING

Four midwestern hospitals serving a diverse population of patients.

PATIENTS

Two hundred seventy-six adult patients who had undergone abdominal surgery (51% men, 49% women; mean age 54.1 +/- 5.3 years).

OUTCOME MEASURES

PPC developed in 26.4%.

DATA COLLECTION

Data were collected preoperatively during a brief interview and a pulmonary physical examination and on the first 6 postoperative days.

RESULTS

A six risk-factor model was tested in this sample of subjects. The model validated relatively well in the sample of 276 subjects with use of the basic criteria of correct classification, sensitivity, and specificity. However, when a new model was developed from this sample, differing risk factors emerged as significant independent predictors.

CONCLUSIONS

Further research is needed to assess the stability of the risk factors and test the models in differing settings and populations of patients.