Can portable chest x-ray examination accurately diagnose lung consolidation after major abdominal surgery? A comparison with computed tomography scan

Diagnostic performance of chest CT average intensity projection (AIP) reconstruction for the assessment of pleuro-parenchymal abnormalities

AIM

The comparison between chest x-ray (CXR) and computed tomography (CT) images is commonly required in clinical practice to assess the evolution of chest pathological manifestations. Intrinsic differences between the two techniques, however, limit reader confidence in such a comparison. CT average intensity projection (AIP) reconstruction allows obtaining "synthetic" CXR (s-CXR) images, which are thought to have the potential to increase the accuracy of comparison between CXR and CT imaging. We aim at assessing the diagnostic performance of s-CXR imaging in detecting common pleuro-parenchymal abnormalities.

MATERIALS AND METHODS

142 patients who underwent chest CT examination and CXR within 24 hours were enrolled. CT was the standard of reference. Both conventional CXR (c-CXR) and s-CXR images were retrospectively reviewed for the presence of consolidation, nodule/mass, linear opacities, reticular opacities, and pleural effusion by 3 readers in two separate sessions. Sensitivity, specificity, accuracy and their 95% confidence interval were calculated for each reader and setting and tested by McNemar test. Inter-observer agreement was tested by Cohen's K test and its 95%CI.

RESULTS

Overall, s-CXR sensitivity ranged 45-67% for consolidation, 12-28% for nodule/mass, 17-33% for linear opacities, 2-61% for reticular opacities, and 33-58% for pleural effusion; specificity 65-83%, 83-94%, 94-98%, 93-100% and 79-86%; accuracy 66-68%, 74-79%, 89-91%, 61-65% and 68-72%, respectively. K values ranged 0.38-0.50, 0.05-0.25, -0.05-0.11, -0.01-0.15, and 0.40-0.66 for consolidation, nodule/mass, linear opacities, reticular opacities, and pleural effusion, respectively.

CONCLUSION

S-CXR images, reconstructed with AIP technique, can be compared with conventional images in clinical practice and for educational purposes.

Correlation between tuberculosis-specific interferon-γ release assay and intrathoracic calcification: A cross-sectional study

Background

Although persistent tuberculosis (TB) infection is known to cause calcification in the lungs, the relationship between intrathoracic calcification and the results of the interferon-γ release assay (IGRA) has not been fully elucidated. This study aimed to assess the association between intrathoracic calcification and IGRA results.

Methods

We retrospectively included consecutive patients who concurrently underwent chest X-ray, chest computed tomography (CT), and an IGRA. Patients with a current diagnosis of active TB or treatment history of active TB or latent tuberculosis infection (LTBI) were excluded. The association between calcification according to the chest X-ray or CT and IGRA results were analyzed using binomial logistic regression.

Results

This study included 574 patients, and 38 (7%) patients had a positive IGRA result. Patients with a positive result were significantly older and had a higher proportion of comorbidities, and history of tuberculosis exposure compared to those with a negative result. Calcification of the lung field and mediastinal lymph nodes according to chest CT was more frequently observed in patients with a positive IGRA result, whereas no significant difference was observed concerning the proportion of lung field calcification on chest X-ray between patients with positive and negative IGRA results. In multivariate analysis, calcification of mediastinal lymph nodes alone (adjusted odds ratio [OR] = 3.82, 95% confidence interval [CI] = 1.76–8.26) and the combination of lung field and mediastinal lymph node calcification (adjusted OR = 4.12, 95% CI = 1.51–11.76) on chest CT was independently associated with positive IGRA results.

Conclusions

The finding of mediastinal lymph node calcification, with or without lung field calcification, on chest CT was associated with positive IGRA results independent of TB exposure history. Previous TB infection including eliminated TB infection and LTBI can be suspected when calcified lymph nodes in are observed the mediastinum on chest CT.

Comparison of conventional chest x ray with a novel projection technique for ultra-low dose CT

PURPOSE

To compare a novel thick-slab projection technique for ultra-low dose computed tomography (CT; thoracic tomogram) with conventional chest x ray with respect to 13 diagnostic categories.

METHODS

With the approval of the institutional ethics board, a dataset was retrospectively collected of 22 consecutive patients who had undergone a clinically requested emergency room conventional chest x ray (CXR) and a same-day standard-of-care non-contrast CT. Scanner specific noise was added to the CT images to simulate a target dose of 0.18 mSv. A novel algorithm was used to post-process CT images as coronal isotropic reformats by applying a voxel-based, locally normalized weighted-intensity projection to generate 2 cm thick slabs with 1 cm overlap. Three chest radiologists with no prior training for the study reviewed the CXR and thoracic tomogram for each case and assessed each diagnostic category (pneumonic infiltrates, pulmonary edema, interstitial lung disease, nodules > 5 mm, nodules < 5 mm, pleural effusion, pericardial effusion, heart size, acute bone fractures, foreign bodies, pneumothorax, mediastinal vessel diameter, free abdominal air) on a Likert scale from -4 (definitely absent/normal) to +4 (definitely present/abnormal). MRMC ROC curves were generated for each category. Time for interpretation and subjective image quality score (0-10) were also assessed.

RESULTS

For focal lung disease (pneumonic infiltrates, nodules < 5 mm, nodules > 5mm), the area under the ROC curve (AUC) was significantly higher for thoracic tomograms than CXR (0.803 vs 0.648, respectively, P = 0.02). For non-focal lung disease (pulmonary edema, interstitial lung disease) and effusions (pulmonary, pericardial), the AUC was larger for thoracic tomograms than CXR but the difference did not reach significance (0.870 vs 0.833, P = 0.141; and 0.823 vs 0.752, P = 0.296, respectively). For acute bone fractures and foreign bodies, the AUC was smaller for thoracic tomograms than CXR, the difference was however not significant (0.491 vs 0.532, P = 0.42; and 0.871 vs 0.971, P = 0.39, respectively). Other diagnostic categories had no true positive cases in the dataset. The mean time for interpretation for each was 36.9 and 24.0 s with standard deviations of 0.857 and 5.977. The image quality score for each was 8.2 and 7.8 with standard deviations of 0.970 and 1.614.

CONCLUSION

Thoracic tomograms were found to be diagnostically superior to CXR for focal lung disease, at no increased radiation dose. The thoracic tomogram presents an opportunity to improve the standard-of-care for patients who would otherwise receive a conventional CXR.

Comparative Performance of Pulmonary Ultrasound, Chest Radiograph, and CT Among Patients With Acute Respiratory Failure

OBJECTIVES

The study goal was to concurrently evaluate agreement of a 9-point pulmonary ultrasound protocol and portable chest radiograph with chest CT for localization of pathology to the correct lung and also to specific anatomic lobes among a diverse group of intubated patients with acute respiratory failure.

DESIGN

Prospective cohort study.

SETTING

Medical, surgical, and neurologic ICUs at a 670-bed urban teaching hospital.

PATIENTS

Intubated adults with acute respiratory failure having chest CT and portable chest radiograph performed within 24 hours of intubation.

INTERVENTIONS

A 9-point pulmonary ultrasound examination performed at the time of intubation.

MEASUREMENTS AND MAIN RESULTS

Sixty-seven patients had pulmonary ultrasound, portable chest radiograph, and chest CT performed within 24 hours of intubation. Overall agreement of pulmonary ultrasound and portable chest radiograph findings with correlating lobe ("lobe-specific" agreement) on CT was 87% versus 62% (p < 0.001), respectively. Relaxing the agreement definition to a matching CT finding being present anywhere within the correct lung ("lung-specific" agreement), not necessarily the specific mapped lobe, showed improved agreement for both pulmonary ultrasound and portable chest radiograph respectively (right lung: 92.5% vs 65.7%; p < 0.001 and left lung: 83.6% vs 71.6%; p = 0.097). The highest lobe-specific agreement was for the finding of atelectasis/consolidation for both pulmonary ultrasound and portable chest radiograph (96% and 73%, respectively). The lowest lobe-specific agreement for pulmonary ultrasound was normal lung (79%) and interstitial process for portable chest radiograph (29%). Lobe-specific agreement differed most between pulmonary ultrasound and portable chest radiograph for interstitial findings (86% vs 29%, respectively). Pulmonary ultrasound had the lowest agreement with CT for findings in the left lower lobe (82.1%). Pleural effusion agreement also differed between pulmonary ultrasound and portable chest radiograph (right: 99% vs 87%; p = 0.009 and left: 99% vs 85%; p = 0.004).

CONCLUSIONS

A clinical, 9-point pulmonary ultrasound protocol strongly agreed with specific CT findings when analyzed by both lung- and lobe-specific location among a diverse population of mechanically ventilated patients with acute respiratory failure; in this regard, pulmonary ultrasound significantly outperformed portable chest radiograph.

Impact of four different recumbencies on the distribution of ventilation in conscious or anaesthetized spontaneously breathing beagle dogs: An electrical impedance tomography study

The aim was to examine the effects of recumbency and anaesthesia on distribution of ventilation in beagle dogs using Electrical Impedance Tomography (EIT). Nine healthy beagle dogs, aging 3.7±1.7 (mean±SD) years and weighing 16.3±1.6 kg, received a series of treatments in a fixed order on a single occasion. Conscious dogs were positioned in right lateral recumbency (RLR) and equipped with 32 EIT electrodes around the thorax. Following five minutes of equilibration, two minutes of EIT recordings were made in each recumbency in the following order: RLR, dorsal (DR), left (LLR) and sternal (SR). The dogs were then positioned in RLR, premedicated (medetomidine 0.01, midazolam 0.1, butorphanol 0.1 mg kg^-1 iv) and pre-oxygenated. Fifteen minutes later anaesthesia was induced with 1 mg kg^-1 propofol iv and maintained with propofol infusion (0.1–0.2 mg kg^-1 minute^-1 iv). After induction, the animals were intubated and allowed to breathe spontaneously (FIO₂ = 1). Recordings of EIT were performed again in four recumbencies similarly to conscious state. Centre of ventilation (COV) and global inhomogeneity (GI) index were calculated from the functional EIT images. Repeated-measures ANOVA and Bonferroni tests were used for statistical analysis (p < 0.05). None of the variables changed in the conscious state. During anaesthesia left-to-right COV increased from 46.8±2.8% in DR to 49.8±2.9% in SR indicating a right shift, and ventral-to-dorsal COV increased from 49.8±1.7% in DR to 51.8±1.1% in LLR indicating a dorsal shift in distribution of ventilation. Recumbency affected distribution of ventilation in anaesthetized but not in conscious dogs. This can be related to loss of respiratory muscle tone (e.g. diaphragm) and changes in thoracic shape. Changing position of thoraco-abdominal organs under the EIT belt should be considered as alternative explanation of these findings.

Atelectasis and mechanical ventilation mode during conservative oxygen therapy: A before-and-after study

PURPOSE

The purpose of the study is to assess the effect of a conservative oxygen therapy (COT) (target SpO2 of 90%-92%) on radiological atelectasis and mechanical ventilation modes.

MATERIALS AND METHODS

We conducted a secondary analysis of 105 intensive care unit patients from a pilot before-and-after study. The primary outcomes of this study were changes in atelectasis score (AS) of 555 chest radiographs assessed by radiologists blinded to treatment allocation and time to weaning from mandatory ventilation and first spontaneous ventilation trial (SVT).

RESULTS

There was a significant difference in overall AS between groups, and COT was associated with lower time-weighted average AS. In addition, in COT patients, change from mandatory to spontaneous ventilation or time to first SVT was shortened. After adjustment for baseline characteristics and interactions between oxygen therapy, radiological atelectasis, and mechanical ventilation management, patients in the COT group had significantly lower "best" AS (adjusted odds ratio, 0.28 [95% confidence interval {CI}, 0.12-0.66]; P=.003) and greater improvement in AS in the first 7 days (adjusted odds ratio, 0.42 [95% CI, 0.17-0.99]; P=.049). Moreover, COT was associated with significantly earlier successful weaning from a mandatory ventilation mode (adjusted hazard ratio, 2.96 [95% CI, 1.73-5.04]; P<.001) and with shorter time to first SVT (adjusted hazard ratio, 1.77 [95% CI, 1.13-2.78]; P=.013).

CONCLUSIONS

In mechanically ventilated intensive care unit patients, COT might be associated with decreased radiological evidence of atelectasis, earlier weaning from mandatory ventilation modes, and earlier first trial of spontaneous ventilation.

Atelectasis as a cause of postoperative fever: where is the clinical evidence?

BACKGROUND

Atelectasis is considered to be the most common cause of early postoperative fever (EPF) but the existing evidence is contradictory. We sought to determine if atelectasis is associated with EPF by analyzing the relevant published evidence.

METHODS

We performed a systematic search in PubMed and Scopus databases to identify studies examining the association between atelectasis and EPF.

RESULTS

A total of eight studies, including 998 cardiac, abdominal, and maxillofacial surgery patients, were eligible for analysis. Only two studies specifically examined our question, and six additional articles reported sufficient data to be included. Only one study reported a significant association between postoperative atelectasis and fever, whereas the remaining studies indicated no such association. The performance of EPF as a diagnostic test for atelectasis was also assessed, and EPF performed poorly (pooled diagnostic OR, 1.40; 95% CI, 0.92-2.12). The significant heterogeneity among the studies precluded a formal metaanalysis.

CONCLUSION

The available evidence regarding the association of atelectasis and fever is scarce. We found no clinical evidence supporting the concept that atelectasis is associated with EPF. More so, there is no clear evidence that atelectasis causes fever at all. Large studies are needed to precisely evaluate the contribution of atelectasis in EPF.

[Agreement between lung ultrasonography and chest radiography in the intensive care unit]

OBJECTIVE

Because the chest radiograph currently remains the routine choice of imaging for the examination of the chest in the intensive care unit, we compared lung ultrasonography with chest radiography.

STUDY DESIGN

Observational prospective study.

METHODS

An ultrasound examination and chest radiography were simultaneously ordered in 50 patients whose clinical exam justified a lung exploration. Each exam was interpreted independently by an intensivist. The abnormalities found were classified into interstitial syndrome, alveolar consolidation, and pleural effusion. An agreement analysis was performed between the results of the two techniques. The delay between the order and interpretation of both investigations, and the degree of interobserver agreement were also collected.

RESULTS

The kappa agreement between lung ultrasonography and chest radiography was 0.42. In total, 329 total abnormalities were detected, 156 abnormalities were found by both techniques, 31 by radiography alone, and 142 by ultrasonography alone. The interobserver agreement was 0.86. Ultrasonography was performed with a shorter delay (14.8 ± 6.9 min vs 44.2 ± 21.4 min).

CONCLUSION

There was only moderate agreement between lung ultrasonography and chest radiography for the diagnosis of interstitial syndrome, alveolar consolidation and pleural effusion in intensive care unit. This result is mainly explained by the higher number of ultrasound abnormalities. With the ability to provide fast diagnosis, good reproducibility and high feasibility, ultrasound scan could represent an alternative exam for chest exploration in intensive care unit.

Ultrasound in the evaluation of interstitial pneumonia

BACKGROUND

The diagnostic value of thoracic ultrasonography (US) has recently increased. Skilled sonographers with experience in pulmonary medicine have demonstrated the existence of US signs of chest pathology.

PURPOSE

To detect US findings associated with infectious interstitial pneumonia that can be used to supplement other diagnostic tools.

MATERIALS AND METHODS

Over a period of 5 years (2001-2006), 55 patients were referred to our ultrasonography units for evaluation of probable viral or viral-like infections of the respiratory tract. Each patient was subjected to a work-up that included clinical examination, blood tests, pulmonary function tests, bronchoscopy, chest radiographs, high-resolution computed tomography (HRCT), and thoracic US, which was performed under blinded conditions.

RESULTS

Based on the findings that emerged from the work-up described above, all 55 patients were diagnosed with interstitial pneumonia. Evaluation of the US scans for the signs of interstitial lung disease described by Lichtenstein revealed "comet-tail" artifacts in the anterolateral lung fields in 31 (56.36%) patients and mixed patterns consisting in increased density associated with ring-down artifacts in 24 (46.64%). Pleural involvement was also observed in 34 cases (61.82%).

CONCLUSIONS

Thoracic US appears to be a useful adjunct to clinical, laboratory and radiological studies in patients suspected of having infectious interstitial pneumonia.

Radiology in the intensive care unit (Part I)

The increasing complexity of the intensive care patient combined with the recent advances in imaging technology has generated a new perspective on intensive care radiology. The purpose of this 2-part review article is to describe the contribution of radiology to the management of these critically ill patients. The first article will discuss the impact of picture archiving and communication system (PACS) on critical care management and utility of the portable chest radiograph in the detection and evaluation of pulmonary disease with correlation to computed tomography (CT). The second article describes in more detail the increasing role of CT in diagnosis and therapeutic procedures. In particular, the implementation of CT pulmonary angiography in the evaluation of pulmonary emboli and the introduction of the new multislice detector CT scanners that allow even the most dyspneic patient to be evaluated. Pleural complications in the intensive care unit and image-guided intervention will also be 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.

Effects of cardiothoracic physiotherapy on intrapulmonary shunt in abdominal surgical patients

This study investigated the provision of additional evening physiotherapy on pulmonary complications and intrapulmonary shunt (Qs/Qt) after abdominal surgery. Thirty-one elderly patients received either daylight only or daylight plus evening physiotherapy for up to 48 hours. Physiotherapy included combinations of positioning, gravity assisted drainage, breathing exercises, manual techniques, coughing and airway suctioning. Measurements included Qs/Qt and post-operative pulmonary complications. While no significant difference in atelectasis was found, the post-operative Qs/Qt data averaged into six-hour time frames demonstrated significantly lower mean Qs/Qt for the daylight plus evening physiotherapy group between 18 and 24 hours post-surgery. Additional evening physiotherapy may reduce post-operative deterioration in gas exchange after major abdominal surgery.

Improvement of 'dynamic analgesia' does not decrease atelectasis after thoracotomy

There is still controversy concerning the beneficial aspects of 'dynamic analgesia' (i.e. pain while coughing or moving) on the reduction of postoperative atelectasis. In this study, we tested the hypothesis that thoracic epidural analgesia (TEA) prevents these abnormalities as opposed to multimodal analgesia with i.v. patient controlled analgesia (i.v. PCA) after thoracotomy. Fifty-four patients undergoing thoracotomy (lung cancer) were randomly assigned to one of the two groups. Clinical respiratory characteristics, arterial blood gas, and pulmonary function tests (forced vital capacity and forced expiratory volume in 1 s) were obtained before surgery and on the next 3 postoperative days. Atelectasis was compared between the two groups by performing computed tomography (CT) scan of the chest at day 3. Postoperative respiratory function and arterial blood gas values were reduced compared with preoperative values (mean (SD) FEV1 day 0: 1.1 (0.3) litre; 1.3 (0.4) litre) but there was no significant difference between groups at any time. PCA and TEA provided a good level of analgesia at rest (VAS day 0: 21 (15/100); 8 (9/100)), but TEA was more effective for analgesia during mobilization (VAS day 0: 52 (3/100); 25 (17/100)). CT scans revealed comparable amounts of atelectasis (expressed as a percentage of total lung volume) in the TEA (7.1 (2.8)%) and in the i.v. PCA group (6.71 (3.2)%). There was no statistical difference in the number of patients presenting with at least one atelectasis of various types (lamellar, plate, segmental, lobar).

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.

Pulmonary Infections in Ventilated Patients: Diagnostic and Therapeutic Options

The diagnosis of pulmonary infections in the ventilated patient has threatened the foundations of medicine. Although the lifesaving techniques of endotracheal intubation (developed for the treatment of diphtheria) and artificial ventilation (developed for the management of poliomyelitis) contribute greatly to medical care, they have resulted in the production of the "progress"-related infection of ventilator-associated pneumonia (VAP). Modern ventilator therapy is a substantial technologic advance from earlier days and, as technology inherently does, has removed some of the human element, the main foundation of Oslerian medical practice. The time-honored clinical diagnosis based on physical examination by an experienced physician has been seriously compromised in the approach to VAP.

Synchronization of radiograph film exposure with the inspiratory pause. Effect on the appearance of bedside chest radiographs in mechanically ventilated patients

The appearance of portable chest radiographs (CXRs) may be affected by changes in ventilation, particularly when patients are mechanically ventilated. Synchronization of the CXR with the ventilatory cycle should limit the influence of respiratory variation on the appearance of the CXR. This study evaluates the effect of synchronizing the CXR film exposure with ventilation on the appearance of the radiograph. Twenty-five patients who remained intubated postoperatively, were mechanically ventilated, and required a CXR were enrolled in this triple-blind, randomized prospective study. Each patient received one radiograph using conventional techniques and another using the interface. The sequence of the two films was randomized, and the two films were taken on the same patient within a few minutes of each other. Hence, each patient served as his own control and the position of the patient, source-film distance, intensity (Kvp), and duration of the exposure (mAs) were identical for the two films. Five board-certified radiologists were then asked to compare paired films for clarity of lines and tubes, definition of the pulmonary vasculature, visibility of the mediastinum, definition of the diaphragm, and degree of lung inflation. Radiologists were also asked to choose which films they preferred. A majority of board certified radiologists preferred CXRs taken with the interface in 21 of 25 patients (p < 0.0001). Furthermore, four of the five criteria evaluated were improved (p < 0.05) on synchronized CXRs. Synchronization of the bedside CXR with the end of inspiration ensures that they are always obtained at maximal inflation, which improves the appearance of a majority of radiographs by at least one of five criteria.

Diagnostic testing for ventilator-associated pneumonia

This article discusses the interpretation of the diagnostic tests in the management of ventilated patients with suspicion of pneumonia. The specific steps for diagnostic evaluation are identified. An accurate interpretation of the significance of the bacterial burden requires previous evaluation of the sample quality, knowledge of administration of new antibiotics within the prior 48 hours, and evaluation of presence of comorbidities. Finally, the article presents a review of the current debate of impact on outcome.

Effect of combined kinetic therapy and percussion therapy on the resolution of atelectasis in critically ill patients

BACKGROUND

Some critically ill patients have difficulty in mobilizing their respiratory secretions. These patients can develop pulmonary atelectasis that may result in hypoxemia. There are some data to show that atelectasis may be prevented by turning a patient from side to side utilizing special beds.

STUDY OBJECTIVES

To determine the role of kinetic therapy (KT) combined with mechanical percussion (P) in the resolution of established atelectasis of the lungs and hypoxemia in critically ill, hospitalized patients. (KT was defined as rotation of a patient along the longitudinal axis of > or = 40 degrees to each side continuously.)

DESIGN

Prospective and randomized study (2:1 test to control group).

PATIENTS

Twenty-four patients with respiratory failure, either mechanically ventilated or spontaneously breathing, who demonstrated segmental, lobar, or unilateral entire lung atelectasis were studied.

SETTING

Medical ICU and adult respiratory ward in a county hospital in New York.

INTERVENTIONS

Seventeen patients were treated with KT combined with mechanical P using a KT system (Triadyne Kinetic Therapy System; KCI; San Antonio, TX). Seven patients received manual repositioning and manual P every 2 h. Both groups received similar conventional therapy with inhaled bronchodilators and suctioning.

RESULTS

Partial or complete resolution of atelectasis was seen in 14 of 17 patients (82.3%) in the test group as compared with 1 of 7 patient (14.3%) in the control group. The median duration to resolution of atelectasis was 4 days in the test group. Bronchoscopy was performed in 3 of 7 patients in the control group, but in none of the patients in the test group. A cost of $720 was incurred per patient for utilizing the specialty beds for a mean duration of 4 days. An improvement in oxygenation index occurred in the test group (change in baseline PaO2/fraction of inspired oxygen from 207.4+/-106.7 mm Hg to 318+/-100.7 mm Hg) at the end of therapy, while the control group showed a reduction over a similar duration of time (181.3+/-96.3 mm Hg to 112+/-21.2 mm Hg).

CONCLUSIONS

KT and mechanical P therapy resulted in significantly greater partial or complete resolution of atelectasis as compared with conventional therapy. There was a generalized trend toward statistical significance in the improvement of oxygenation and a reduced need for bronchoscopy in the group receiving KT and P therapy.

Infection versus colonization in the critical care unit

Serious infections in the critical care unit are commonplace. However, distinguishing true infection from mere colonization is a difficult and often uncertain process that has been shown to result in both over- and under-treatment of patients. Antimicrobial agents used in the CCU setting are expensive and not without toxicities. This article discusses methods to differentiate colonization from infection.

Bronchoscopic diagnosis of pneumonia

Lower respiratory tract infections are characterized by significant morbidity and mortality but also by a relative inability to establish a specific etiologic agent on clinical grounds alone. With the recognized shortcomings of expectorated or aspirated secretions toward establishing an etiologic diagnosis, clinicians have increasingly used bronchoscopy to obtain diagnostic samples. A variety of specimen types may be obtained, including bronchial washes or brushes, protected specimen brushings, bronchoalveolar lavage, and transbronchial biopsies. Bronchoscopy has been applied in three primary clinical settings, including the immunocompromised host, especially human immunodeficiency virus-infected and organ transplant patients; ventilator-associated pneumonia; and severe, nonresolving community- or hospital-acquired pneumonia in nonventilated patients. In each clinical setting, and for each specimen type, specific laboratory protocols are required to provide maximal information. These protocols should provide for the use of a variety of rapid microscopic and quantitative culture techniques and the use of a variety of specific stains and selective culture to detect unusual organism groups.

Accuracy of portable chest radiography in the critical care setting. Diagnosis of pneumonia based on quantitative cultures obtained from protected brush catheter

Sixty-six supine portable chest radiographs done on the day of bronchoscopy in 62 critical care unit patients suspected of having pneumonia were examined in a blinded fashion by two radiologists. Quantitative culture results obtained from protected brush catheter (PBC) specimens were compared with chest radiograph scores. For one observer, the sensitivity of the chest radiograph for predicting the presence of positive culture results was 0.60, specificity was 0.29, overall agreement was 0.41, positive predictive value was 0.34, and negative predictive value was 0.55. For the second observer, the values were as follows: sensitivity, 0.64; specificity, 0.27; overall agreement, 0.41; positive predictive value, 0.35; and negative predictive value, 0.55. The kappa statistic was calculated at 0.27 indicating marginal interobserver reproducibility. We conclude the portable chest radiograph in the critical care setting is not accurate in predicting the presence of pneumonia when the diagnosis is based on quantitative cultures obtained from protected brush catheter specimens.