Utility of Gram's stain and efficacy of quantitative cultures for posttraumatic pneumonia: a prospective study

Bronchoalveolar lavage in diagnosis of ventilator-associated pneumonia in patients with burns

Ventilator-associated pneumonia (VAP) remains a major cause of morbidity and mortality for patients with burns. In nonburn populations, bronchoalveolar lavage (BAL) excludes other pathology such as systemic inflammatory response syndrome. We hypothesized that BAL would decrease our false-positive VAP rate. All ventilated patients with burn injury who were admitted to our institution from July 2000 through June 2003 were included. After June 2001, BAL was used to make the diagnosis of VAP, with > or =10(4) organisms considered a positive result. Fifty patients met criteria for VAP, 21 in the pre-BAL period and 29 in the BAL period. Six patients (21%) in the BAL group had quantitative cultures <10(4) and were not treated. The outcomes for these patients were not different than those treated for VAP. There were no differences in age, TBSA size, antibiotic use, or ventilator days for the pre-BAL or BAL groups, although the pneumonia rate was lower for the BAL time period. The use of BAL eliminated the unnecessary antibiotic treatment of 21% of patients in the BAL time period and was associated with a lower rate of VAP.

Ventilator-associated pneumonia in injured patients: do you trust your Gram's stain?

BACKGROUND

The results of sputum or bronchoalveolar lavage (BAL) fluid Gram's stain have been used to guide presumptive antibiotic therapy for ventilator-associated pneumonia (VAP) in injured patients, despite reported variability in sensitivity, specificity, positive predictive value, negative predictive value, and accuracy. Our aim was to evaluate the utility of Gram's stain of BAL fluid in the diagnosis of VAP.

METHODS

We conducted a retrospective chart review of all mechanically ventilated trauma patients who developed pneumonia over a 5-year period in whom Gram's stain and final culture data were available.

RESULTS

One hundred fifty-five records with complete data sets were reviewed. VAP was diagnosed by Centers for Disease Control and Prevention criteria and confirmed by BAL and quantitative culture in all patients. Overall accuracy of Gram's stain in diagnosing VAP for any organism was 88% (137 true-positives). When assessed for the ability to predict pneumonia caused by a specific organism, the accuracy decreased significantly, with only 63% of Gram-negative VAPs and 72% of Gram-positive VAPs accurately identified by Gram's stain. However, the absence of Gram-positive organism of Gram's stain excludes Gram-positive VAP in 80% of patients.

CONCLUSION

All trauma patients should be covered presumptively for gram-negative organisms, as they encompass 70% of infections, but are not reliably identified by Gram's stain. As 88% of VAP can be identified by the presence of any organism on Gram's stain, it may be useful in the early diagnosis of VAP but cannot reliably be used to guide presumptive therapy.

Is ventilator-associated pneumonia in trauma patients an epiphenomenon or a cause of death?

BACKGROUND

Ventilator-associated pneumonia (VAP) is a common infection among patients in trauma intensive care units (ICUs). It has been suggested by different investigators that VAP is an indicator of injury severity and not necessarily associated with mortality. Crude mortality rates approximating 20% have been reported for trauma patients with VAP. Most studies have involved the most severely injured patients, making it difficult to determine the relative contribution of either VAP or injury severity to death. If VAP is independently associated with mortality, this relationship should be most evident in less severely injured patients. We studied patients with less severe injuries (Injury Severity Score, ISS < 25) to determine the impact of VAP on outcomes.

METHODS

Patients admitted to the trauma ICU with ISS < 25 were identified from the trauma registry of a level I trauma center. Patients with penetrating injuries and those who died within 48 h of injury were excluded. Pneumonia was diagnosed using quantitative cultures of bronchoalveolar lavage effluent (>/= 10(5) colony forming units/mL). Risk factors for VAP, including age, transfusions with 24 h of admission, brain injury, and chest injury severity were analyzed. Logistic regression analysis was then performed to determine independent factors for death.Results: There were 15,492 blunt admissions over a 5.5 year study period who survived >48 h. Of these, 5,860 (38%) were admitted to the ICU, and 4,111 (70% of ICU admissions) had ISS < 25. The incidence of VAP in this group was 8%. Patients with VAP were older (47 vs 39 years), had more transfusions within 24 h (2.5 vs 0.9 units of red blood cell concentrates) and had greater injury severity by ISS (16.7 vs 12.6 points), GCS (Glasgow Coma Scale) score (11.8 vs. 13.7 points) and chest AIS (Abbreviated Injury Scale) (1.7 vs 0.9 points; all p < 0.001). Overall mortality was 4%. Mortality was 16% in patients with VAP compared to 3% in those without VAP (p < 0.0001). Logistic regression analysis identified transfusions, age, and VAP as independent predictors of mortality. Other descriptors of injury severity (ISS, GCS, or chest AIS) were not associated with death.

RESULTS

There were 15,492 blunt admissions over a 5.5 year study period who survived . 48 h. Of these, 5,860 (38%) were admitted to the ICU, and 4,111 (70% of ICU admissions) had ISS , 25. The incidence of VAP in this group was 8%. Patients with VAP were older (47 vs 39 years), had more transfusions within 24 h (2.5 vs 0.9 units of red blood cell concentrates) and had greater injury severity by ISS (16.7 vs 12.6 points), GCS (Glasgow Coma Scale) score (11.8 vs. 13.7 points) and chest AIS (Abbreviated Injury Scale) (1.7 vs 0.9 points; all p , 0.001). Overall mortality was 4%. Mortality was 16% in patients with VAP compared to 3% in those without VAP (p , 0.0001). Logistic regression analysis identified transfusions, age, and VAP as independent predictors of mortality. Other descriptors of injury severity (ISS, GCS, or chest AIS) were not associated with death.

CONCLUSIONS

Ventilator-associated pneumonia is independently associated with death in less severely injured trauma patients. This demonstrates the need for effective diagnostic techniques so that adequate therapy may be initiated. Prevention of VAP in less severely injured trauma patients should increase survival.

Effect From Multiple Episodes of Inadequate Empiric Antibiotic Therapy for Ventilator-Associated Pneumonia on Morbidity and Mortality Among Critically Ill Trauma Patients

BACKGROUND

Empiric antibiotic therapy is routinely initiated for patients with presumed ventilator-associated pneumonia (VAP). The impact of inadequate empiric antibiotic therapy (IEAT) may vary among critically ill populations. The purpose of this retrospective study was to determine the effect of IEAT on the outcome for adult trauma patients with VAP.

METHODS

This study enrolled 82 patients with multiple VAP episodes (200 VAP episodes; mean, 2.4 +/- 0.65 per patient; range, 2-5 episodes). An episode of IEAT was a VAP episode with empiric therapy having no in vitro activity against causative bacteria. Overall, there were 78 (39%) IEAT episodes involving 54 patients. Most often, IEAT was attributable to the presence of Acinetobacter spp, Stenotrophomonas maltophilia, or Alcaligenes xylosoxidans. All the patients received appropriate definitive therapy according to the final culture. The patients were classified by number of IEAT episodes: 0 (n = 28), 1 (n = 34), and more than 1 (n = 20).

RESULTS

Demographics and injury severity were similar among the groups. The mortality rate was 3.6% for no episodes, 8.8% for one episode, and 45% for more than one episode (p < 0.001). On the basis of multiple logistic regression, experiencing multiple IEAT episodes was independently associated with the risk of death (odds ratio, 4.28; 95% confidence interval, 1.44-12.71). Additionally, experiencing multiple IEAT episodes was associated with prolonged intensive care unit stay (p = 0.007) and prolonged mechanical ventilation (p = 0.005).

CONCLUSIONS

Critically ill trauma patients experiencing multiple episodes of IEAT for VAP have increased morbidity and mortality. These findings reinforce the importance of developing and refining a unit-specific pathway for the empiric management of VAP.

The appropriate diagnostic threshold for ventilator-associated pneumonia using quantitative cultures

BACKGROUND

The use of quantitative cultures of the bronchoalveolar lavage (BAL) effluent to distinguish between posttraumatic inflammatory response and ventilator-associated pneumonia (VAP) is becoming more common. However, the diagnostic threshold of either 10 or 10 colonies/mL remains debatable. Because mortality from VAP is related to treatment delay, some have chosen a lower diagnostic threshold (>10 colonies/mL). This may result in unnecessary antibiotic use with its sequelae: increased resistant organisms, antibiotic-related complications, and increased costs. The purpose of this study is to determine the optimal diagnostic threshold for VAP diagnosis using quantitative cultures of the BAL effluent.

METHODS

Data on patients with fiberoptic bronchoscopy with BAL are maintained in a prospectively collected database at our Level I trauma center. This database was reviewed for timing and frequency of BAL and the colony counts of each organism identified. Indication for bronchoscopy was clinical evidence of VAP. VAP was defined as >10 colonies/mL in the BAL effluent. A false-negative BAL was defined as any patient who had <10 colonies/mL and developed VAP with the same organism up to 7 days after the previous culture.

RESULTS

Over a 46-month period, 526 patients underwent 1,372 fiberoptic bronchoscopy procedures with BAL. Of these, 72% were male patients, 91% followed blunt injury, and mean age and Injury Severity Score were 43 years and 30, respectively. Overall mortality was 14%. There were 1,898 organisms identified (42% were gram-positive and 58% were gram-negative). VAP was diagnosed in 38% of BAL. Overall, there were 43 episodes in 38 patients defined as false-negative (3%). The false-negative rate was 9% in patients with 10 organisms. The most common false-negative organisms were Pseudomonas and Acinetobacter species.

CONCLUSION

The VAP diagnostic threshold for quantitative BAL in trauma patients should be >10 colonies/mL. One may consider a threshold of >10 colonies/mL in severely injured patients with Pseudomonas or Acinetobacter species.

A time-dependent analysis of intensive care unit pneumonia in trauma patients

BACKGROUND

Appropriate and timely antibiotic therapy to treat pneumonia in trauma patients is extremely important. We evaluated the incidence and microbiology of pneumonia stratified by days postadmission and risk factors.

METHODS

Prospective data were collected on 714 trauma patients admitted to the intensive care unit over a 1-year period. Pneumonia was classified as community acquired (CAP) (< or = 3 days), early nosocomial (ENP) (4-6 days), or late nosocomial (LNP) (> or = 7 days). In addition, pneumonia was classified as CAP only, nosocomial only (NI), or combination (CAP and NI, or ENP and LNP) pneumonia. Strict institutional guidelines were followed for diagnosis.

RESULTS

One hundred eighty-two patients (25%) were diagnosed with 204 pneumonias over the study period. One hundred twenty-five (61%) of these pneumonias were ventilator associated. Staphylococcus aureus and Haemophilus influenzae were the most common pathogens isolated. Twenty-one percent of patients with CAP acquired an LNP (p < 0.025), in which Pseudomonas was the most common organism. Haemophilus caused LNP in 12% of patients. Cancer (p < 0.01), liver failure (p < 0.05), and age (p < 0.01) were predictive of nontypical pathogens in patients with CAP and ENP (p < 0.05). Obesity was most predictive of increased ventilator days (p < 0.001) and intensive care unit length of stay (p < 0.001). Increased age, alcohol abuse, and field airway were most predictive of mortality.

CONCLUSION

Unanticipated pathogens were isolated in each class of pneumonia. The clinician must be aware of significant risk factors that may predispose patients to pathogens that are not ordinarily covered with standard antibiotic therapy.

Value of the clinical pulmonary infection score for the identification and management of ventilator-associated pneumonia

OBJECTIVE

To evaluate the potential ability of an algorithm based on the clinical pulmonary infection score (CPIS) to identify and treat patients with bacterial ventilator-associated pneumonia (VAP) compared to a strategy based on quantitative cultures of bronchoscopic specimens.

DESIGN

Retrospective cohort study.

SETTING

Thirty-one critical care units across France.

PATIENTS

Two hundred and one patients clinically suspected of having VAP who had been included in the "invasive strategy" group of the French multicenter randomized trial and for whose quantitative cultures bronchoscopic specimens were obtained. CPIS was determined retrospectively, based on data that had been collected for the initial study.

INTERVENTIONS

None.

MEASUREMENTS AND RESULTS

The clinical pulmonary infection score was determined on days 1 and 3, and compared in patients identified as having developed VAP or not, as defined by bronchoscopic specimen culture results. On day 3 138 of the 201 patients (69%) had a CPIS of more than 6 that would have required prolonged antimicrobial therapy based on the algorithm. In contrast, based on bronchoscopy, only 88 (44%) patients were considered to have VAP (kappa coefficient for concordance between the two strategies, 0.33). While the sensitivity of CPIS more than 6 on day 3 for identifying VAP was 89%, its specificity was only 47%, leading to potentially unnecessary treatment of 60 (53%) of the 113 patients without VAP as diagnosed by bronchoscopy.

CONCLUSION

A strategy based on the CPIS to decide which patients with suspected VAP should receive prolonged administration of antibiotics would appear to over-prescribe these agents, as compared to a strategy based on bronchoscopy.

Tetracyclines for treating multidrug-resistant Acinetobacter baumannii ventilator-associated pneumonia

OBJECTIVE

To report the use of tetracyclines for the treatment of multidrug-resistant Acinetobacter baumannii ventilator-associated pneumonia (VAP).

DESIGN

Observational case series.

SETTING

. The Presley Regional Trauma Center located within the Regional Medical Center, Memphis, Tennessee, USA.

PATIENTS AND PARTICIPANTS

Seven critically ill trauma patients with VAP caused by A. baumannii isolates that were resistant to all antibiotics tested except for doxycycline or minocycline.

INTERVENTIONS

Patients were treated with IV doxycycline or minocycline for an average of 13.5 (range 9-20) days.

MEASUREMENTS AND RESULTS

Doxycycline or minocycline was successful in six of seven patients.

CONCLUSIONS

Doxycycline or minocycline may be effective for treating multidrug-resistant A. baumannii VAP.

The Predictive Value of Preliminary Bacterial Colony Counts from Bronchoalveolar Lavage in Critically Ill Trauma Patients

A common strategy for the diagnosis of ventilator-associated pneumonia (VAP) includes quantitative cultures from bronchoalveolar lavage (BAL). Often, empiric antibiotic therapy is initiated and continued until the final culture report. However, approximately 60 per cent of BAL cultures rule out VAP. Preliminary BAL results, obtained earlier, may identify these patients and allow early discontinuation of empiric antibiotics. This is desirable because unnecessary antibiotic therapy results in increased bacterial resistance, adverse drug events, and increased costs. The purpose of this study was to determine the value of preliminary BAL results for predicting final BAL results. A total of 1579 isolates from 868 BAL cultures over a 3-year period were analyzed. Preliminary and final colony counts for each isolate were categorized as either no growth (NG), insignificant (1–99,999 cfu/mL), or significant (≥100,000 cfu/mL). Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of preliminary results were calculated based on individual isolates and individual BAL samples. The presence of concurrent antibiotic therapy was collected for all false-negative isolates. On preliminary report, there were 367 isolates with NG, 820 isolates with insignificant growth, and 392 isolates with significant growth. Overall preliminary culture results had a sensitivity of ∼90 per cent and specificity of >90 per cent for the presence of VAP. Preliminary culture results accurately predicted the presence or absence of VAP in 838 (96.5%) of the BALs performed. Individual isolates and BAL samples with insignificant preliminary growth had greater reliability in predicting the absence of VAP than those with NG. There was no difference in the number of false-negative isolates that were taken while concurrent antibiotic therapy was present between insignificant and NG groups. Preliminary culture results yielding either insignificant or significant growth are highly predictive for final colony counts of similar magnitude. BALs with preliminary results demonstrating no growth are not as reliable. Isolates with significant preliminary growth should be considered clinically important, and antibiotic therapy should be changed, if necessary, to target such organisms. Isolates with insignificant preliminary growth have a low rate of false negatives; therefore, empiric antibiotic therapy specific for such organisms could be discontinued before obtaining final results. Empiric antibiotics should be continued until the final results are available in those patients with NG BALs.

Optimal threshold for diagnosis of ventilator-associated pneumonia using bronchoalveolar lavage

BACKGROUND Identification of ventilator-associated pneumonia (VAP) with invasive methods such as bronchoalveolar lavage (BAL) paired with treatment is associated with improved mortality. Inappropriate antibiotic use, however, is known to increase bacterial resistance, making future treatment problematic. Thus, the diagnostic threshold for VAP in BAL must yield adequate sensitivity while limiting exposure of patients to unnecessary antibiotics. Our institution uses a cutoff of > or = 10(5) colony-forming units (CFUs)/mL, but the optimal cutoff remains an area of debate. In this project, the effects of lower diagnostic cutoffs on VAP diagnosis and unnecessary antibiotic use are examined.

METHODS

Records of all patients admitted to the trauma intensive care unit over a 2-year period requiring > 48 hours of mechanical ventilation were reviewed. Number of BALs, quantity of organism on each BAL, and presence of VAP (> or = 10(5) CFUs/mL) were noted. Indication for BAL was pulmonary infiltrate, sepsis syndrome, and C-reactive protein > 17 microg/dL at > or = 48 hours after admission.

RESULTS

From January 1, 2000, to December 31, 2001, 563 patients were admitted to the trauma intensive care unit. Two hundred fifty-seven required > 48 hours of mechanical ventilation, and 257 BALs were performed in 168 (65%) of these patients. One hundred thirty-nine episodes of VAP occurred in 109 (42%) patients. Subdiagnostic quantities of bacteria (> or = 10(2) but < 10(5) CFUs/mL) were seen in 98 BALs. Of these, only 16 (16%) episodes of VAP with the same organism were seen later during hospitalization. At a threshold of > or = 10(4) CFUs/mL, 4 of 28 (14%) patients went on to develop pneumonia. A similar pattern was seen at diagnostic thresholds of > or = 10(3) CFUs/mL (10 of 72 [14%]) and > or = 10(2) CFUs/mL (16 of 98 [16%]).

CONCLUSION

A threshold of > or = 10(5) CFUs/mL for VAP diagnosis carries a low false-negative rate. Over 80% of additional patients who would have been treated had a threshold of > or = 10(4) CFUs/mL been used recovered without treatment and thus would have undergone unnecessary antibiotic exposure. A similar pattern is seen at all lower thresholds. Lower diagnostic thresholds would lead to marginal increase in sensitivity, and many would receive unnecessary VAP treatment with potential for increasing bacterial resistance.

Prophylactic antibiotics adversely affect nosocomial pneumonia in trauma patients

BACKGROUND

Little data are available regarding the impact that prolonged prophylactic antibiotic use (>48 hours) has on the development of nosocomial pneumonia. This retrospective study was conducted to assess the effect that prolonged prophylactic antibiotic use has on the development of nosocomial pneumonia and antibiotic use complications.

METHODS

The records of patients who contracted nosocomial pneumonia during mechanical ventilation were retrospectively reviewed. These patients then were classified into two groups: those who received prolonged prophylactic antibiotics before the diagnosis of pneumonia and those who did not receive antibiotics.

RESULTS

For the patients who received prolonged prophylactic antibiotics, the first pneumonia was diagnosed later, the causative organisms were more likely to be resistant or Gram-negative bacteria, and the incidence of antibiotic complications were two times greater than for patients who did not receive extended antibiotic prophylaxis.

CONCLUSION

Justification for the use and duration of prolonged (>48 hours) prophylactic antibiotics requires careful reevaluation because this practice is associated with significant clinical complications that lead to increased use of patient resources, lengthened hospital stay, and higher cost.

Preventing antimicrobial-resistant bacterial infections in surgical patients

BACKGROUND

The Centers for Disease Control and Prevention (CDC) has identified the control of antimicrobial resistance as an important effort to reduce the morbidity and mortality associated with health care. Methods to prevent these infections in surgical patients have rarely been addressed specifically.

METHODS

The peer-reviewed literature and published guidelines were examined to identify proven or suggested techniques for controlling antimicrobial resistance that would be particularly relevant to surgeons and the surgical patient population.

RESULTS

A multi-step approach to the prevention of antimicrobial-resistant infections in surgical patients was developed. This program consists of four major strategies: Infection prevention, effective diagnosis and treatment of infection, optimal antibiotic utilization, and the prevention of transmission.

CONCLUSION

The control of antimicrobial resistance in bacteria is an important objective for all physicians, including surgeons. An approach to attain this goal in surgical populations is outlined. Further research will be needed to determine the value of these practices and to develop newer, even more effective interventions.

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.

Does bronchoalveolar lavage enhance our ability to treat ventilator-associated pneumonia in a trauma-burn intensive care unit?

BACKGROUND

Recent literature supports the notion that bronchoalveolar lavage (BAL) in ventilated trauma patients may improve our ability to diagnose and treat ventilator-associated pneumonia (VAP). We hypothesized that BAL would decrease the number of cases of VAP diagnosed and impact our antibiotic use and ventilator days.

METHODS

Prospective data on all infectious complications were collected for patients admitted to the trauma-burn service for the year 2001. All VAPs between January 1, 2001, through June 30, 2001, were diagnosed without BAL (No BAL group) using clinical signs of fever, sputum production, leukocytosis, chest radiographs, and sputum culture. After July 1, 2001, VAP was diagnosed with the use of BAL.

RESULTS

There were 37 cases of VAP in the No BAL group (11%) and 29 cases of VAP (8%) in the BAL group. There were no statistical differences in Injury Severity Score, hospital length of stay, ventilator days, or mortality between the two groups. The time to initial treatment of VAP was shorter for the BAL group, but did not reach significance. The number of patients who had their VAP pathogens correctly treated with empiric antibiotics was also the same between the two groups. There was no difference in the rate of recurrent pneumonias. The antibiotic costs and respiratory therapy/ventilator costs were not statistically different between the groups for trauma patients, although antibiotic costs were higher for burn patients.

CONCLUSION

The routine use of BAL to diagnose VAP in our mixed trauma-burn population did not impact on clinical outcomes or antibiotic use. Our results do not justify the additional costs and potential risks of BAL for all patients. The means of VAP diagnosis may not be as important as choosing the appropriate antibiotics for common VAP organisms in any given intensive care unit.

A formula for prediction of posttraumatic pneumonia based on early anatomic and physiologic parameters

BACKGROUND

Identification of risks for development of ventilator-associated pneumonia (VAP), which might be identified early after injury, would allow for prognostic estimates and targeting of high-risk cohorts for clinical trials of preventive strategies. This study was performed to develop an equation that can be applied to estimate the probability of pneumonia based on parameters collected in the early postinjury interval.

METHODS

Over a 28-month period, patient admissions were reviewed for mechanism and severity of injury, patterns of injury, shock, and need for emergent intubation. Early deaths (<48 hours) were excluded. VAP diagnosis required > or = 10(5) colony-forming units/mL organisms in the bronchoalveolar lavage effluent. Multiple logistic regression analysis was used to develop the prediction equation and estimate odds ratios. The equation was then tested on consecutive patients admitted over a 2-month period.

RESULTS

We reviewed 9,721 admissions (77% blunt, 23% penetrating). VAP incidence was 5.6%. Overall mortality was 2% (21% for patients with VAP vs. 1% for no VAP; p < 0.0001). Multiple logistic regression analysis for all patients produced the following equation: f(x) = -3.08 - 1.56 (MOI) - 0.12 (GCS) + 1.37 (SCI) + 0.30 (chest AIS) + 1.87 (lap) + 0.67 (tx) + 0.05 (ISS) + 0.66 (int), where MOI is mechanism of injury (penetrating = 1, blunt = 0), GCS is Glasgow Coma Scale score, SCI is spinal cord injury (yes = 1, no = 0), lap is emergent laparotomy (yes = 1, no = 0), ISS is Injury Severity Score, tx is units of blood transfused in the resuscitation room, and int is intubation in either the field or the resuscitation room (yes = 1, no = 0). The probability of VAP was calculated as follows: P(VAP) = e(f)(x)/1 + e(f)(x). This formula was concordant in 95% and discordant in 5%.

CONCLUSION

It is possible to accurately predict risk for VAP in trauma patients based on data available early after injury. This calculation could be useful for counseling families relative to prognosis and research protocols, and addressing hospitalization issues with third-party payors.

Pediatric trauma: postinjury care in the pediatric intensive care unit

Traumatic injuries occur in > 20 million children each year and are the leading source of death in children over the age of 1 yr. Mechanisms of injury and subsequent therapies for critically injured children are diverse. This review will focus on resources and management strategies for caring for the severely injured child in the pediatric intensive care unit.

Does gender difference influence outcome?

BACKGROUND

Recent laboratory studies have demonstrated that immune responses differ between male and female rodents, and some clinical studies have suggested gender differences regarding incidence and mortality from sepsis. The differences appear because of both deleterious testosterone and beneficial estrogen effects; clinical trials of testosterone blockage and/or estrogen administration for male subjects have been suggested. We evaluated the effect of gender on various outcomes in trauma patients.

METHODS

Trauma patients over a 52-month period were identified from the trauma registry. Early deaths were excluded. Outcomes included mortality, pneumonia (> or = 10 colony-forming units/mL in bronchoalveolar lavage effluent), acute respiratory distress syndrome, bacteremia, ventilator days, and intensive care unit and hospital length of stay. Patients were stratified by injury mechanism, gender, age (assuming women < or = 40 were premenopausal and those > 50 were postmenopausal), and injury severity.

RESULTS

There were 18,133 patients identified, and 544 were excluded because of early death. There were 12,756 (73%) men and 4,833 (27%) women. There were no outcome differences after penetrating injury with respect to gender and age group. There was a survival advantage for women < or = 40 in the Injury Severity Score 16 to 24 group, but these patients had statistically less severe injury. Overall, men tended to have more infectious complications, but women had lower survival in the face of infection. Logistic regression did not identify gender as an independent predictor of mortality.

CONCLUSION

Although there was a survival advantage for women in subgroup analysis, there was no overall difference in mortality. Women with pneumonia, however, had a higher mortality than men. Further understanding of potential mechanisms is necessary before hormonal manipulation studies.

Treatment of aspiration in intensive care unit patients

BACKGROUND

Aspiration is a common event, but the clinical consequences are variable. The primary determinants are the nature of the aspirated material and the host response to it. The purpose of this paper is to present treatment algorithms that should be employed in critically ill patients who experience aspiration.

METHODS

Expert review of the available literature was done to provide background information to support the logic of 3 treatment algorithms: (1) treatment of acute aspiration pneumonitis; (2) pulmonary care for acute aspiration; and (3) treatment of aspiration pneumonia.

RESULTS

The discussion of aspirations is separated into 2 clinical scenarios: (1) aspiration pneumonitis (sterile inflammation) versus (2) aspiration pneumonia (an infectious process). Aspiration pneumonitis should be treated by aggressive pulmonary care to enhance lung volume and clear secretions. Intubation should be used selectively. Early corticosteroids and prophylactic antibiotics are not indicated. Treatment of aspiration pneumonia requires diligent surveillance for the clinical signs of pneumonia. Treatment decisions are based on 3 factors: (1) clinical diagnostic certainly (definite versus probable), (2) time of onset [early (< 5 days) versus late (> or = 5 days)], and (3) host factors (high risk versus low risk). There is no ideal antibiotic regimen. Unit-specific resistance patterns and known frequency pathogens should direct broad spectrum empiric therapy. Invasive diagnostic techniques (such as bronchoalveolar lavage) should be used when the diagnosis is not certain. Antibiotic coverage should be narrowed once sputum culture results become available.

CONCLUSIONS

Aspiration is common in critically ill patients and should be aggressively treated by these treatment algorithms.

Lactobacillus species as a cause of ventilator-associated pneumonia in a critically ill trauma patient

Lactobacillus species are ubiquitous inhabitants of the human gastrointestinal and genitourinary tracts and rarely cause infections. Pneumonia caused by Lactobacillus has been reported only in immunocompromised patients and in one patient with structural lung disease. A 39-year-old, immunocompetent, critically ill woman developed ventilator-associated pneumonia, which was found to be caused by Lactobacillus. To our knowledge, this is the first such report. The infection was treated successfully with 14 days of intravenous vancomycin. Based on this case, Lactobacillus should be considered a possible cause of ventilator-associated pneumonia in immunocompetent, critically ill patients.

Risk factors for late-onset nosocomial pneumonia caused by Stenotrophomonas maltophilia in critically ill trauma patients

Patients with nosocomial pneumonia caused by Stenotrophomonas maltophilia often receive inadequate empiric antibiotic therapy, potentially increasing mortality. Knowledge of the risk factors associated with S. maltophilia pneumonia may better guide the selection of empiric antibiotic therapy. Potential risk factors for S. maltophilia pneumonia were retrospectively analyzed for critically ill trauma patients with late-onset gram-negative pneumonia. The effects of S. maltophilia infection and inadequate empiric antibiotic therapy on patient outcomes were also assessed. By multivariate analysis, S. maltophilia pneumonia was found to be associated with cefepime exposure and tracheostomy in patients with a single pneumonia episode and with higher Injury Severity Score and pulmonary contusion in patients with multiple pneumonia episodes. S. maltophilia pneumonia was associated with increased patient morbidity; only inadequate empiric antibiotic therapy was associated with a higher mortality rate. In critically ill trauma patients with late-onset ventilator-associated pneumonia and these risk factors, empiric antibiotic therapy should include agents active against S. maltophilia.

Aerosolized ceftazidime for prevention of ventilator-associated pneumonia and drug effects on the proinflammatory response in critically ill trauma patients

STUDY OBJECTIVES

To evaluate the safety and efficacy of aerosolized ceftazidime for prevention of ventilator-associated pneumonia (VAP) and to evaluate the effects of the drug on the proinflammatory response.

DESIGN

Prospective, randomized, double-blind, placebo-controlled clinical trial.

SETTING

University teaching hospital.

PATIENTS

Forty critically ill trauma patients at high risk for VAP Intervention. Within 48 hours of admission to the intensive care unit (ICU), patients were randomly assigned to receive aerosolized ceftazidime 250 mg every 12 hours or placebo (normal saline) for up to 7 days. Bronchoalveolar concentrations of tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-1beta, IL-6, and IL-8 were determined at baseline and the end of therapy (days 4-7).

MEASUREMENTS AND MAIN RESULTS

The frequency of VAP in patients receiving aerosolized ceftazidime was 73% lower than that in patients receiving placebo at ICU day 14 (15% vs 55%, p = 0.021), and 54% lower for the entire ICU stay (30% vs 65%, p = 0.022). No clinically significant changes in bacterial culture and sensitivity patterns were observed. No adverse events from aerosolized ceftazidime were reported. Pulmonary TNF-alpha, IL-beta, and IL-8 concentrations were attenuated in the ceftazidime group compared with those in the placebo group (p < 0.001, p = 0.02, and p = 0.003). The frequency of VAP was related directly to changes in TNF-alpha and IL-beta (p < 0.001, p = 0.02).

CONCLUSIONS

Aerosolized ceftazidime decreased the frequency of VAP in critically ill trauma patients, without adversely affecting ICU flora. Aerosolized ceftazidime also may attenuate the proinflammatory response in the lung.

Reproducibility of blind protected bronchoalveolar lavage in mechanically ventilated children

Blind protected bronchoalveolar lavage (BAL) could be an interesting tool in the diagnosis of ventilator-associated pneumonia in intubated children, but its reproducibility has never been evaluated. This study evaluates the reproducibility, feasibility, and safety of blind protected BAL in mechanically ventilated children. Two blind protected BAL were done, at a 2-hour interval, in 30 patients. The reproducibility of microbiologic and cytologic results was studied. A total of 60 BALs was analyzed. Bacterial growth was present in 26 of 60 BAL (43%). Reproducibility for the presence of bacteria on quantitative cultures was excellent (concordance, 93%; kappa [kappa], 0.86). Concordance for the type of bacteria isolated was 86% and for the number of bacteria was 79%. Reproducibility for the presence of neutrophils containing bacteria was perfect (concordance, 100%; kappa, 1) although only a few BALs had a positive result (8/60). Blind protected BAL was feasible in all patients and all samples were considered adequate for analysis. Complications were mostly benign and transitory except in two cases: one pneumothorax and one significant increase in intracranial pressure. Overall, blind protected BAL is a reproducible test in mechanically ventilated children, is easily feasible, and is usually well tolerated.

Comparison of ampicillin-sulbactam and imipenem-cilastatin for the treatment of acinetobacter ventilator-associated pneumonia

Acinetobacter organisms, which are a common cause of ventilator-associated pneumonia (VAP) in some health care centers, are becoming more resistant to such first-line agents as imipenem-cilastatin (Imi-Cil). Sulbactam has good in vitro activity against Acinetobacter organisms; thus, ampicillin-sulbactam (Amp-Sulb) may be a viable treatment alternative. The outcomes for critically ill trauma patients with Acinetobacter VAP treated with either Amp-Sulb or Imi-Cil were compared retrospectively. A total of 77 episodes in 75 patients were studied. Fourteen patients were treated with Amp-Sulb, and 63 patients were treated with Imi-Cil. Treatment efficacy was similar in the Amp-Sulb and Imi-Cil groups (93% vs. 83%, respectively; P>.05). No statistically significant differences between groups were noted with regard to associated mortality, duration of mechanical ventilation, or length of stay in the intensive care unit or hospital. However, adjunctive aminoglycoside therapy was used more often in the Amp-Sulb group. Patients generally received Amp-Sulb because of imipenem resistance. Amp-Sulb was effective in treating a small number of patients with Acinetobacter VAP; however, more data are needed.

Infection control: avoiding the inevitable

Infection, while a major cause of morbidity, should not be considered an inevitable consequence of injury. Good aseptic technique, compulsive attention to detail, and thorough understanding of the points addressed in the following list of critical points are the best guarantee that infection will not add avoidable morbidity to misfortune. Critical points regarding infectious problems in care of the injured child: 1. Polymicrobial infection is the rule with 50% of isolates being mixed aerobic and anaerobic bacteria. 2. It is a misnomer to consider antibiotic use in a pediatric trauma victim as prophylactic. Antimicrobials used in this setting are best considered adjunctive. 3. The major indication for anti-infective therapy in pediatric trauma is an injury with a high probability of infection. 4. Antibiotics do not sterilize the wound or body cavity; they limit bacterial proliferation, thereby supplementing effective immune control. 5. Available studies suggest that 24 hours is as efficacious as a longer treatment duration in a purely adjunctive mode. 6. In bites inflicted by dogs and cats, Pasturella species are frequent. 7. Human bites may result in infection by Eikenella corrodens. 8. Based on this bacteriology, adjunctive intravenous ampicillin sulbactam or oral amoxicillin clavulanate are recommended for human and animal bites. 9. Tetanus prophylaxis is indicated in all significant soft tissue injuries. 10. Risk of osteomyelitis correlates directly with the extent of the associated soft tissue injury and vascular compromise. 11. The majority of infectious complications in the injured child are not a consequence of the injury itself, but rather in the treatment thereof. 12. In the injured child the most common nosocomial infection is lower respiratory followed by primary blood stream and the urinary tract. 13. The management of nosocomial pneumonia in the injured child is based on the time of diagnoses. Early evidence of pulmonary infection requires treatment with a third generation cephalosporin with or without an antistaphylococcal penicillin. Late pneumonia is treated with an aminoglycoside with or without an antipseudomonal added. 14. Catheter related infection is, in the injured child, overwhelmingly gram positive with coagulase negative staphlococcal species accounting for 30-60% of isolates. Staphlococcus aureus is responsible for an additional 15-20%. 15. The role of antibiotics in the prevention of catheter related meningitis is controversial. Recent adult studies suggest no advantage to their routine use. If utilized, they should only be employed prophylactically and not continued throughout the monitoring period. 16. Lack of response to treatment of sepsis may represent an inappropriate antimicrobial agent, improper dosage, inability to achieve adequate levels at the site of infection. (eg, CSF) fungal pathogen, and/or ongoing contamination or undrained purulent focus.

Ventilator-associated pneumonia

Ventilator-associated pneumonia (VAP) continues to complicate the course of 8 to 28% of patients receiving mechanical ventilation (MV). In contrast to infections of more frequently involved organs (e.g., urinary tract and skin), for which mortality is low, ranging from 1 to 4%, the mortality rate for VAP ranges from 24 to 50% and can reach 76% in some specific settings or when lung infection is caused by high-risk pathogens. The predominant organisms responsible for infection are Staphylococcus aureus, Pseudomonas aeruginosa, and Enterobacteriaceae, but etiologic agents widely differ according to the population of patients in an intensive care unit, duration of hospital stay, and prior antimicrobial therapy. Because appropriate antimicrobial treatment of patients with VAP significantly improves outcome, more rapid identification of infected patients and accurate selection of antimicrobial agents represent important clinical goals. Our personal bias is that using bronchoscopic techniques to obtain protected brush and bronchoalveolar lavage specimens from the affected area in the lung permits physicians to devise a therapeutic strategy that is superior to one based only on clinical evaluation. When fiberoptic bronchoscopy is not available to physicians treating patients clinically suspected of having VAP, we recommend using either a simplified nonbronchoscopic diagnostic procedure or following a strategy in which decisions regarding antibiotic therapy are based on a clinical score constructed from seven variables. Selection of the initial antimicrobial therapy should be based on predominant flora responsible for VAP at each institution, clinical setting, information provided by direct examination of pulmonary secretions, and intrinsic antibacterial activities of antimicrobial agents and their pharmacokinetic characteristics. Further trials will be needed to clarify the optimal duration of treatment and the circumstances in which monotherapy can be safely used.

Antibacterial treatment of invasive mechanical ventilation-associated pneumonia

Patients admitted to intensive care units (ICU) are at higher risk of acquiring nosocomial infections than patients in other hospital areas. This is the consequence of both a greater severity of illness with its implications (manipulation, invasiveness) and crossed infection from reservoirs inside the ICU. The most frequent nosocomial infection is invasive ventilation-associated pneumonia (VAP) which leads to an important increase in morbidity and mortality. The most important aetiological agents in VAP are bacteria, with a marked predominance of Staphylococcus aureus and Pseudomonas aeruginosa. These aetiologies may be different depending upon the type of ICU (medical, surgical, coronary) or the presence of certain risk factors (duration of mechanical ventilation before onset of pneumonia, previous exposure to antibacterials). Susceptibilities of the aetiological agents to antibacterials may also vary according to the type of ICU and over time. Data from global studies show an increase in multiresistant bacteria but these data may not be applied to a local ICU. The availability of accurate and updated information on the most frequently encountered organisms in each ICU and their susceptibilities is very important in order to provide the most adequate treatment. A controversial issue is the selection of antibacterials. According to the latest evidence the most adequate approach is a prompt administration of empirical treatment. Based on knowledge of bacterial flora in our own ICU, the choice of an adequate therapeutic regimen will decrease both morbidity and mortality. A second issue is monotherapy versus combined therapy. The most common recommendation, with a few exceptions, is to use combined therapy until microbiological results are received. Another controversy is the choice of antibacterials in the combined regimen. The most commonly recommended combination is that of a beta-lactam with an aminoglycoside, except in early-onset pneumonia without risk factors. The use of monotherapy with a cefalosporin without antipseudomonal activity or amoxicillin-clavulanic acid is the recommended regimen. Treatment should be modified based on microbiological results. There are no well documented recommendations on the prophylactic duration of treatment and it must be based on the aetiological agent and the clinical course. In summary treatment of VAP must be prompt, empirical and combined (beta-lactam plus aminoglycoside ). However, the choice of the antibacterial regimen should follow local guidelines of treatment based upon the knowledge of the most frequently isolated bacterial flora and their susceptibilities in different clinical settings.

ARDS after pulmonary contusion: accurate measurement of contusion volume identifies high-risk patients

BACKGROUND

The pathophysiology of pulmonary contusion (PC) is poorly understood, and only minimal advances have been made in management of this entity over the past 20 years. Improvement in understanding of PC has been hindered by the fact that there has been no accurate way to quantitate the amount of pulmonary injury. With this project, we examine a method of accurately measuring degree of PC by quantifying contusion volume relative to pulmonary function and outcome.

METHODS

Patients with PC from isolated chest trauma who had admission chest computed tomographic scan were identified from the registry of a Level I trauma center over a 1.5-year period. Subsequently, prospective data on all patients admitted to the intensive care unit with PC during a 5-month period were collected and added to the retrospective database. Using computer-generated three-dimensional reconstruction from admission chest computed tomographic scan, contusion volume was measured and expressed as a percentage of total lung volume. Admission pulmonary function variables (Pao2/FiO2, static compliance), injury descriptors (chest Abbreviated Injury Score, Injury Severity Score, injury distribution), and indicators of degree of shock (admission systolic blood pressure, admission base deficit) were documented. Outcomes included maximum positive end-expiratory pressure, ventilator days, pneumonia, and acute respiratory distress syndrome (ARDS).

RESULTS

Forty-nine patients with PC (35 bilateral) were identified. The average severity of contusion was 18% (range, 5-55%). Patients were classified using contusion volume as severe PC (> or =20%, n = 17) and moderate PC (< 20%, n = 32). Injury Severity Score was similar in the severe and moderate groups (23.3 vs. 26.5, p = 0.33), as were admission Glasgow Coma Scale score (12 vs. 13, p = 0.30), admission blood pressure (131 vs. 129 mm Hg, p = 0.90), and admission Pao2/Fio2 (197 vs. 255, p = 0.14). However, there was a much higher rate of ARDS in the severe group as compared with the moderate group (82% vs. 22%, p < 0.001). There was a trend toward higher pneumonia rate in the severe group, with 50% of patients in the severe group developing pneumonia as compared with 28% in the moderate group (p = 0.20).

CONCLUSION

Extent of contusion volumes measured using three-dimensional reconstruction allows identification of patients at high risk of pulmonary dysfunction as characterized by development of ARDS. This method of measurement may provide a useful tool for the further study of PC as well as for the identification of patients at high risk of complications at whom future advances in therapy may be directed.

An evaluation of the Gram stain in protected bronchoalveolar lavage fluid for the early diagnosis of ventilator-associated pneumonia

We investigated the usefulness and reliability of the Gram stain value versus quantitative cultures in the early diagnosis of ventilator-associated pneumonia (VAP) using the protected bronchoalveolar lavage (PBAL). One hundred four mechanically ventilated patients (age = 52 +/- 19; SAPS II = 38 +/- 15) with a strong suspicion of VAP were consecutively included. One hundred sixteen PBAL were performed and mini-bronchoalveolar lavage were analyzed using the Gram stain standard method and the conventional quantitative culture technique. VAP diagnosis was based on a positive quantitative culture of mini-bronchoalveolar lavage fluid (cutoff > or = 10(3) CFU/mL). A final diagnosis of VAP was established in 67 patients and there was no infection in 49 cases. Regarding detection of bacteria using the Gram stain, we found a sensitivity of 76.2%, a specificity of 100%, a positive predictive value of 100% and a negative predictive value of 75.4%. There was a good agreement with the final diagnosis (kappa statistic 0.73; concordance 86.2%). The degree of qualitative agreement between Gram stain and quantitative cultures was analyzed in the VAP group: the correlation was complete in 39% (26 of 67 VAP), partial in 28% (19 of 67 VAP) and there was no correlation in 33% (22 of 67 VAP). We conclude that despite its overall "good agreement," the Gram stain is of limited use for the rapid diagnosis of VAP and unreliable for the early adaptation of empirical antimicrobial therapy when using the noninvasive PBAL procedure.

Identification of Early Predictors for Post-Traumatic Pneumonia

We demonstrated that the standard clinical criteria of fever, leukocytosis, purulent sputum, and infiltrate on chest radiograph are nonspecific for the diagnosis of post-traumatic pneumonia, and only ∼50 per cent of patients with these conditions have pneumonia. Quantitative cultures of bronchoalveolar lavage effluent will differentiate pneumonia (requiring antibiotic therapy) from systemic inflammatory response syndrome (not requiring antibiotics). Early identification of patients at risk for pneumonia can target populations for clinical research. Because risk factors for pneumonia when diagnosed by quantitative cultures have not been defined we reviewed our recent experience to identify variables predictive of pneumonia. Patients over a 22-month period who survived >48 hours were identified from the trauma registry. Pneumonia was defined as growth of ≥105 organisms per milliliter in the bronchoalveolar lavage effluent. Risk factors evaluated included injury severity and severity of shock. There were 7503 patients (75% with blunt and 25% with penetrating injuries). The incidence of pneumonia was 6 per cent (7% of patients with blunt and 2% of patients with penetrating injuries). Logistic regression analysis identified age; Glasgow Coma Scale score; Injury Severity Score; transfusion requirements during resuscitation; spinal cord injury; chest injury severity; and emergent femur fixation, craniotomy, and laparotomy as being independent predictors of pneumonia. We conclude that multiple risk factors, which are all able to be determined early after injury, are predictive of post-traumatic pneumonia. Prompt identification of this high-risk group of patients allows prognostic considerations relative to patient management schemes and targets populations for prophylactic measures or immunomodulation.

Effects of Empiric Antibiotic Administration for Suspected Pneumonia on Subsequent Opportunistic Pulmonary Infections

Optimal guidelines for empiric antibiotic (EAB) therapy in cases of suspected post-traumatic ventilator-associated pneumonia (VAP) are not well defined. EAB administration is thought to increase the incidence of opportunistic organisms; however, culture-directed (as opposed to empiric) treatment may delay antibiotic administration with possible adverse consequences. Our goal was to examine the impact of EAB administration on the incidence of subsequent VAP and opportunistic organisms in a series of critically injured patients with sepsis syndrome. This is a retrospective review of all patients admitted to a Level I trauma center who underwent multiple fiberoptic bronchoscopies (FOBs) for diagnosis of suspected VAP as the cause of postinjury sepsis syndrome. The relationships between EAB administration, positive cultures (>105 colony-forming units) at repeat FOB, and prevalence of opportunistic organisms (methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa, Stenotrophomonas species, Acinetobacter species, and/or yeast) were evaluated. Over a 13-month period ending on January 1, 1999, 36 intubated trauma patients underwent more than one FOB during their intensive care unit stay. Twenty-nine patients received EAB immediately after the initial FOB. There was no difference in the rate of EAB administration in patients who developed subsequent VAP after initial FOB (19 of 24,79%) versus those who did not develop VAP (10 of 12, 83%; P = 0.65). There were 30 VAPs diagnosed in 58 subsequent FOBs ( i.e., after the initial FOB) of which 23 were due to an opportunistic organism compared with two VAPs due to an opportunistic organism diagnosed at initial FOB ( P < 0.001). Twenty-one of the 23 opportunistic VAPs at subsequent FOBs had received EAB before the first FOB compared with four of seven nonopportunistic organisms ( P = 0.06). Administration of EAB does not impact the incidence of subsequent VAP. However, EAB may be related to the development of subsequent opportunistic pulmonary infections.

Nosocomial pneumonia in the pediatric trauma patient: a single center's experience

OBJECTIVES

To evaluate a single center's experience with the frequency rate, patterns of occurrence, and impact on outcome of nosocomial pneumonia in the critically injured child.

DESIGN

Retrospective review of prospectively collected data.

SETTING

Level I university trauma center with a pediatric trauma intensive care unit.

PATIENTS

A total of 523 consecutive critically injured children admitted to the pediatric intensive care unit during an 80-month interval.

MEASUREMENTS AND RESULTS

Thirty-five episodes of nosocomial pneumonia were identified in 29 children (frequency rate of 5.5%). The mean age of the children was 9.2 yrs, and the mean Injury Severity Score was 27 +/- 9. In 91% of patients (26 children), nosocomial pneumonia was associated with mechanical ventilation. This represented a 13% frequency rate in injured children who were ventilated during the study period. The most common organisms recovered were Staphylococcus aureus (21%), Haemophilus influenzae (19%), Pseudomonas (11%), and Enterobacter (11%). Early pneumonia (diagnosed < or = 7 days after injury) was predominantly caused by Haemophilus species. In contrast, Enterobacter and/or Pseudomonas were isolated primarily in late pneumonia (diagnosed >7 days after injury). Staphylococcus was prominent throughout the hospitalization. Overall, children with nosocomial pneumonia were more severely injured (Injury Severity Score 27 vs. 17, p < .001) and had a longer hospital stay (26 vs. 7 days, p < .001). Despite this, mortality (6.9% vs. 7.9%, p = NS) was not significantly different from injured children without pneumonia.

CONCLUSIONS

In this study of a single pediatric trauma center, nosocomial pneumonia occurred in a small but significant percentage of injured children. The frequency rate increased two- to three-fold with mechanical ventilation. Microbiology varied with day of onset. In contrast to the adult, mortality did not seem to be significantly altered by this complication. Analysis of additional pediatric trauma centers is encouraged to confirm these characteristics of nosocomial pneumonia in the injured child.

Incidence and susceptibility of pathogenic bacteria vary between intensive care units within a single hospital: implications for empiric antibiotic strategies

BACKGROUND

The purpose of this study was to determine whether the incidence of recovery and patterns of antibiotic susceptibility of pathogenic bacteria vary between intensive care units (ICUs) in a single teaching hospital.

METHODS

Culture and susceptibility results were collected prospectively for a 3-month period (April through June 1999) in each of the surgical, trauma, and medical ICUs. The number of unique isolates and susceptibility patterns were determined. Susceptibility of isolates among ICUs was compared with chi2.

RESULTS

Statistically significant differences between ICUs in susceptibility to various antibiotics were found for Staphylococcus aureus, Enterococcus sp, Acinetobacter sp, Enterobacter sp, Klebsiella sp, and Pseudomonas sp. Notably, vancomycin-resistant Enterococcus was not seen in the medical ICU, whereas it was seen in both the surgical and trauma ICUs. Klebsiella spp resistant to ceftazidime were seen only in the trauma ICU. The aminoglycosides and quinolones had attenuated activity against Pseudomonas sp in the surgical ICU, whereas they remained highly effective in the trauma ICU. Cefazolin had no activity against the Enterobacter sp in either of the surgical ICUs, but was highly effective in the medical ICU.

CONCLUSION

Although the microbiologic results of this study should not be extrapolated to other institutions, the principle is of value. There is variability between ICUs in a single large teaching hospital in susceptibility of bacterial pathogens to various antibiotics. This may have implications in the design of empiric antibiotic strategies and the planning of the hospital formulary. Hospital wide or composite ICU antibiograms are inadequate for planning empiric therapy in the ICU.

Intermittent and continuous ceftazidime infusion for critically ill trauma patients

BACKGROUND

The adequacy of intermittent and continuous infusion ceftazidime for the treatment of nosocomial pneumonia in critically ill trauma patients was assessed by analyzing ceftazidime pharmacokinetics in relation to the minimum inhibitory concentration (MIC) and treatment outcome.

METHODS

Serial blood samples were obtained during ceftazidime therapy in 31 trauma patients. Ceftazidime pharmacokinetics were compared with that of previously studied healthy volunteers. Ceftazidime pharmacokinetics were analyzed according to the time above the MIC and treatment outcome.

RESULTS

Critically ill trauma patients had a significantly increased volume of distribution and clearance (0.32 +/- 0.14 L/kg and 2.35 +/- 0.89 mL. min(-1). kg(-1), respectively) compared with healthy volunteers (0.21 +/- 0.03 and 1.58 +/- 0.23 mL. min(-1). kg(-1)). The time above the MIC was >/=92% of the dosing interval for all patients and treatment outcomes were similar between the two treatment groups.

CONCLUSIONS

Ceftazidime pharmacokinetics are significantly altered in critically ill trauma patients. Both intermittent and continuous ceftazidime regimens were equally effective for the treatment of nosocomial pneumonia caused by less virulent bacteria.

Effects of fiberoptic bronchoscopy on intracranial pressure in patients with brain injury: a prospective clinical study

BACKGROUND

Fiberoptic bronchoscopy (FB) plays an important role in making the diagnosis of nosocomial pneumonia and resolving lobar atelectasis in critically injured trauma patients. It has been shown to be a safe procedure with only occasional complications. However, in patients with head injuries, FB can lead to intracranial hypertension. Sustained increases in intracranial pressure (ICP) leads to poor outcome in these patients. Because of this, a prospective study was done not only to assess the effect of FB on ICP and cerebral perfusion pressure (CPP) in patients with brain injuries, but also to identify a regimen of sedation and anesthesia that could prevent significant increases in ICP during FB.

METHODS

Twenty-six FB were performed in 23 patients with ICP monitors or ICP monitors and ventriculostomy drains in place for Glasgow Coma Scale score < 8 or management of postcraniotomy trauma. FB was performed to aid in the diagnosis of nosocomial pneumonia or to aid in resolving lobar atelectasis. Before FB, all patients received a standard anesthetic regimen consisting of vecuronium (10 mg), morphine sulfate (4 mg), and midazolam (2.5 mg). Patients with diminished cranial compliance, defined as ICP > 10 mm Hg, also received a nebulizer treatment of 3 mL of 4% lidocaine before FB. All patients were preoxygenated with FIO2 = 1.0 for 10 minutes. Intracranial pressure, mean arterial pressure, and CPP were monitored continuously throughout the procedure. These same variables were also recorded at baseline and at 2-minute intervals during the procedure. The time to return to baseline ICP was also recorded.

RESULTS

The mean ICP at baseline (immediately before FB) was 12.6 mm Hg. After introduction of the bronchoscope, the ICP rapidly increased in 21 procedures (81%) and the mean highest ICP was 38.0 mm Hg. There was also a concomitant increase in mean arterial pressure such that there was no substantial change in CPP. The mean lowest CPP was 73.1 mm Hg. The average time for return of ICP to baseline was 13.9 minutes. In the subgroup of patients with ICP > 10, attempting to blunt the tracheal stimulation by anesthetizing the trachea with 4% nebulized lidocaine did not seem to be successful. The mean highest ICP in this subgroup was 41.8 mm Hg. The CPP changed in a similar manner, as the mean lowest CPP was 74.0 mm Hg. The mean time to return to baseline was 12.5 minutes. No patient had acute neurologic deterioration secondary to FB.

CONCLUSIONS

Although FB is an important procedure in the pulmonary care of head injured patients, it produces substantial, but transient, increases in ICP and should be used with caution in patients with diminished cranial compliance. Sedation, analgesia, paralysis, and topical tracheal anesthesia did not completely prevent the rise in ICP. Although no acute deterioration in condition occurred, secondary brain injury caused by localized cerebral ischemia is certainly possible. Because of the substantial increases in ICP, herniation may be precipitated in an occasional patient. Further study is needed to identify a regimen that will confer protection.

Postoperative Pneumonia

Despite the advances made in surgical critical care, the diagnosis of one of the most common infections seen in critically ill patients remains a challenge. Ventilator-associated pneumonia is associated with a 20 to 25 per cent mortality rate. There are numerous risk factors for ventilator-associated pneumonia, including underlying disease, prolonged mechanical ventilation, direct lung injury, and shock. The standard clinical criteria for pneumonia are inaccurate. Quantitative cultures of bronchoalveolar lavage effluent are accurate for the diagnosis, and it is safe to base antibiotic therapy on the results of the quantitative cultures.