Do immature and mature sibling oocytes recovered from stimulated cycles have the same reproductive potential?

RESEARCH QUESTION

How can laboratory and clinical outcomes of spontaneously, early maturing germinal-vesicle oocytes and sibling in-vivo-matured (metaphase II [MII]) oocytes be quantified and compared?

DESIGN

A prospective, non-randomized intra-cohort study of oocytes from women aged 38 years or younger, with six or fewer MII oocytes and four or more germinal vesicles retrieved. No indication was identified for genetic tests or oocyte or embryo cryopreservation. The study was carried out at IVIRMA-Valencia. Early maturing germinal vesicles were selected for reproductive purposes. In vitro- and in-vivo MII oocytes were fertilized. After time-lapse culture, hatching blastocysts from germinal vesicles were biopsied for aneuploidy screening and vitrified. Laboratory and clinical outcomes were compared according to oocyte origin.

RESULTS

Almost 70% of germinal vesicles had matured early and spontaneously, and had comparable in vitro-outcomes and morphokinetics to sibling in vivo-matured oocytes. Fifty per cent of biopsied blastocysts were euploid. Germinal-vesicle rescue increased the number of MII oocytes per cycle to 3.9, finally adding one extra-blastocyst per cycle. A live birth confirmed the feasibility of this approach. Further data, however, are needed to quantify its real contribution to standard intracytoplasmic sperm injection cycles. Nevertheless, 40% of patients obtained either an immediate advantage (reduction of cancellation rate) or long-term benefit (availability of extra blastocysts of attempts).

CONCLUSIONS

Germinal-vesicle rescue can be considered as a complementary approach when folliculometry (expected) and number of MII (observed) are unequal.

A protein encoded by a new family of mobile elements from Euryarchaea exhibits three domains with novel folds

We present here the 2.6A resolution crystal structure of the pT26-6p protein, which is encoded by an ORF of the plasmid pT26-2, recently isolated from the hyperthermophilic archaeon, Thermococcus sp. 26,2. This large protein is present in all members of a new family of mobile elements that, beside pT26-2 include several virus-like elements integrated in the genomes of several Thermococcales and Methanococcales (phylum Euryarchaeota). Phylogenetic analysis suggested that this protein, together with its nearest neighbor (organized as an operon) have coevolved for a long time with the cellular hosts of the encoding mobile element. As the sequences of the N and C-terminal regions suggested a possible membrane association, a deletion construct (739 amino acids) was used for structural analysis. The structure consists of two very similar beta-sheet domains with a new topology and a five helical bundle C-terminal domain. Each of these domains corresponds to a unique fold that has presently not been found in cellular proteins. This result supports the idea that proteins encoded by plasmid and viruses that have no cellular homologues could be a reservoir of new folds for structural genomic studies.

A multicenter, randomized, double-blind, placebo-controlled, dose-finding trial of a long-acting formulation of octreotide in promoting weight loss in obese adults with insulin hypersecretion

OBJECTIVE

To compare changes in weight in obese patients who received long-acting octreotide (octreotide LAR) at one of three dose levels (20, 40, or 60 mg) or placebo over 6 months and to identify the lowest dose of octreotide LAR that safely achieved optimal weight loss.

DESIGN

Randomized, double-blind, placebo-controlled trial of octreotide LAR at three dose levels.

PATIENTS

A total of 172 adults (28 men and 144 women) with at least moderate obesity (body mass index (BMI) range 30-65 kg/m2) and evidence of insulin hypersecretion were enrolled. Patients were predominantly either Caucasian (50.0%) or African American (45.3%). The mean age (38 +/- 11 year), weight (110.7 +/- 23 kg), and BMI (39.8 +/- 6.5 kg/m2) were similar across the four treatment groups.

MEASUREMENTS

Efficacy measures included weight, BMI, fasting serum glucose; triglycerides; percentage of total body fat and abdominal fat as measured by dual-energy X-ray absorptiometry; skin fold thickness; waist-to-hip circumference; leptin; percentage of carbohydrates, fat, and protein ingested; nutritional evaluation (including dietary analysis--3-day food record); quality of life (QoL; using the Impact of Weight on Quality of Life-Lite); Beck Depression Inventory; and Carbohydrate Craving Questionnaire. Safety measures included medical history, vital signs, physical examinations, hematology, blood chemistries, thyroid function tests, hemoglobin A1c, gallbladder ultrasound, electrocardiograms, and adverse events.

RESULTS

After 6 months of treatment, patients receiving 40 or 60 mg of octreotide LAR experienced statistically significant weight loss compared to baseline, with mean differences from placebo in percent weight change of -1.98 and -1.87%, respectively. This finding was accompanied by statistically significant mean decreases in BMI compared to baseline, that is, a mean decrease of 0.73 and 0.79 kg/m2 for the 40 and 60 mg treatment arms, respectively. The observed weight loss was progressive during the 6-month treatment in the two higher dose groups. The lowest dose to reach statistical significance in weight loss after 6 months' treatment was 40 mg. Post hoc analysis revealed a 3.5-3.8% weight loss at month 6 in the two higher dose groups among Caucasian patients having insulin secretion greater than the median of the cohort, defined as CIR(gp) (corrected insulin response at the glucose peak) > or = 1.43. There were no statistically significant changes in QoL scores, body fat, leptin concentration, Beck Depression Inventory, or macronutrient intake. Mean changes of blood glucose AUC(0-180 min) during an oral glucose tolerance test in patients taking octreotide LAR were 39-40 mg/dl h higher than those on placebo. A total of 7-21% of the patients taking octreotide LAR reached a 5% or greater decrease in body weight from Baseline, compared to 11% for the placebo group. This was not statistically significant. The most common adverse events included diarrhea, headache, cholelithiasis, nausea, and abdominal pain.

CONCLUSION

Octreotide LAR given at 40 or 60 mg resulted in statistically significant weight loss. A post hoc analysis stratifying patients by race and CIR(gp) indicated that Caucasian patients with the greater degree of insulin hypersecretion appeared to derive the most benefit from treatment. The observed safety profile was consistent with the known effects of octreotide from previous studies.

Oxidative stress and airway inflammation in severe exacerbations of COPD

BACKGROUND

A study was undertaken to assess both oxidative stress and inflammation in the lungs of patients with chronic obstructive pulmonary disease (COPD) during severe and very severe exacerbations compared with those with stable COPD, healthy smokers, and non-smokers. Two sites within the lungs were compared: the large airways (in sputum) and the peripheral airways (by bronchoalveolar lavage (BAL)).

METHODS

BAL fluid cell numbers and levels of tumour necrosis factor (TNFalpha) and interleukin (IL)-8 were measured as markers of airway inflammation and glutathione (GSH) levels as a marker of antioxidant status. Nuclear translocation of the pro-inflammatory transcription factors nuclear factor-kappaB (NF-kappaB) and activator protein 1 (AP-1) were also measured by electromobility shift assay in BAL fluid leucocytes and lung biopsy samples.

RESULTS

Influx of inflammatory cells into the peripheral airways during exacerbations of COPD was confirmed. Increased IL-8 levels were detected in BAL fluid from patients with stable COPD compared with non-smokers and healthy smokers, with no further increase during exacerbations. In contrast, IL-8 levels in the large airways increased during exacerbations. GSH levels were increased in the BAL fluid of smokers (444%) and patients with stable COPD (235%) compared with non-smokers and were reduced during exacerbations (severe 89.2%; very severe 52.3% compared with stable COPD). NF-kappaB DNA binding in BAL leucocytes was decreased in healthy smokers compared with non-smokers (41.3%, n = 9, p<0.001) but did not differ in COPD patients, whereas AP-1 DNA binding was significantly decreased during exacerbations of COPD.

CONCLUSION

There is evidence of increased oxidative stress in the airways of patients with COPD that is increased further in severe and very severe exacerbations of the disease. This is associated with increased neutrophil influx and IL-8 levels during exacerbations.

Bacterial infection in exacerbated COPD with changes in sputum characteristics

We examined the risk factors for bacterial exacerbation, defined as the presence of pathogenic bacteria in sputum, in 90 chronic obstructive pulmonary disease (COPD) patients with an exacerbation and changes in sputum characteristics. Smoking, alcohol, lung function, body mass index, medical visits and treatments were the independent variables assessed using multivariable logistic regression modelling (OR, 95% CI). A bacterial exacerbation was diagnosed in 39 (43.3%) of 90 patients. Bacterial exacerbations were more prevalent among current smokers (OR 3.77, 95% CI 1.17-12.12), in patients with poor compliance with inhalation therapy (OR 3.25, 95% CI 1.18-8.93) and with severe lung function impairment (FEV1 OR 0.96, 95% CI 0.93-1.00). Prior use of antibiotics was a risk factor for Pseudomonas aeruginosa infection (OR 6.06, 95% CI 1.29-28.44) and influenza vaccination appeared to have a protective effect against this infection (OR 0.15, 95% CI 0.03-0.67). We conclude that severe impairment of lung function, smoking and poor compliance with therapy are risk factors for bacterial infection in COPD, and P. aeruginosa should be suspected in patients who have been treated with antibiotics and in those not vaccinated against influenza.

Induced sputum in the diagnosis of peripheral lung cancer not visible endoscopically

The diagnosis of small peripheral lung cancer is difficult to achieve by non-invasive methods. We hypothesized that in these patients induced sputum might ncrease the diagnostic yield over spontaneous sputum, representing a good diagnostic alternative in selected patients. We prospectively evaluated 60 patients with peripheral lung lesions and normal bronchoscopic evaluation. Six samples of sputum (three spontaneous and three induced with nebulization of hypertonic saline) before bronchoscopy and six samples of sputum after bronchoscopy (three spontaneous and three induced) were obtained in each subject. Forty-two out of the 60 patients included were finally diagnosed with lung cancer. Eighteen patients were diagnosed with different benign conditions of the lung. Overall, malignant cells in sputum were observed in 21 patients and in all but one, the final diagnosis of lung cancer was achieved. Only one patient with a pseudoinflammatory tumour of the lung had a false-positive result in one spontaneous sputum sample. The diagnosis of lung cancer was obtained in 18 patients with the induced sputum (43%) and in 14 patients with spontaneous sputum (31%) (P=NS). Samples of induced sputum were more adequate for cytological analysis than samples of spontaneous sputum (P < 0.001). Of 13 patients with peripheral lung neoplasms of 2 cm or less in diameter, five were diagnosed using induced sputum (38%) and only one using spontaneous sputum (8%) (P<0.05). In conclusion, induced sputum is a valuable technique for the diagnosis of peripheral lung cancer. Induced sputum gives better quality specimens and better diagnostic yield in small lesions than the spontaneous sputum and may be indicated in selected patients with disseminated disease, inoperability or severe co-morbities.

[Impact in the quality of health care and cost-effectiveness analysis of the reform of an emergency medicine service]

BACKGROUND

To determine the effects that the reform of an emergency department (ED) have on efficacy, health care quality and efficiency.

MATERIAL AND METHOD

Reforms consisted of 50% and 34% increases in structural and human resources, respectively. Roles of each ED member were redetermined, new assistance pathways were implemented, and the relationship between ED and the remaining hospital departments was reassessed. As efficacy markers, we determined the number of patients waiting to be attended (Pesp), the waiting time of patients to receive medical assistance (T(esp)),and the total waiting time of patients staying in the ED (T(total)). As health-care quality markers, we determined the percentage of patients leaving ED without having been visited by a physician(IPNV), the percentage of patients who were visited again (IPR),and the percentage of mortality (IPF). We also quantified the number of visits to the ED. All these data were obtained daily over 3 weeks, before (February 1999) and after (February 2000)the reforms. Effectiveness was estimated from the ratio P(total)/T(esp)(E1) and P(total)/P(esp) (E2). Costs were recorded for both periods and a cost-effectiveness analysis was performed to study the efficiency.

RESULTS

In 2000, the number of visits increased by +12% (CI 95%: 2% to 22%). Despite this increase, we observed an improvement of most efficacy and health-care quality markers after the ED reforms. E1 increased by 996% (CI 95%: 335% to 1,658%) and E2 increased by 186% (CI 95%: -23%to 395%). Cost-effectiveness analysis showed 70% (CI 95%: 33%to 107%) and 56% (CI 95%: 18% to 94%) increases regarding E1 and E2, respectively, after the reforms.

CONCLUSIONS

Providing ED with the necessary resources leads to an objective improvement of its efficacy and health-care quality and, consequently, the service and quality perceived by users improve. Despite the total cost increase after the ED reforms, efficiency also improves.

Evaluation of antimicrobial treatment in mechanically ventilated patients with severe chronic obstructive pulmonary disease exacerbations

OBJECTIVE

To study microbial and susceptibility patterns and antimicrobial treatment responses in patients with severe, acute exacerbations of chronic obstructive pulmonary disease requiring mechanical ventilation.

DESIGN

Microbial investigation using tracheobronchial aspirates, bronchoscopy with a protected specimen brush, and bronchoalveolar lavage, as well as paired serologies. Evaluation of antimicrobial treatment by results of the initial investigation, susceptibility testing, and a repeated microbial investigation (tracheobronchial aspirates, bronchoscopy with a protected specimen brush, and bronchoalveolar lavage) after 72 hrs.

SETTING

A respiratory intensive care unit of a 1,000-bed teaching hospital.

PATIENTS

Fifty severely exacerbated and mechanically ventilated patients with chronic obstructive pulmonary disease.

INTERVENTIONS

Initial empirical antimicrobial treatment according to clinical judgment.

MEASUREMENTS AND MAIN RESULTS

Overall, 36 of 50 patients (72%) had evidence of a microbial origin. Community-acquired endogenous pathogens were present in 70% of patients, and Gram-negative enteric bacilli and Pseudomonas/Stenotrophomonas species were present in 30%. All five isolates of Streptococcus pneumoniae were resistant to penicillin (three intermediately and two highly), and three were resistant to multiple antibiotics. Pseudomonas species revealed multiresistance in four of nine isolates (44%), and Stenotrophomonas maltophilia revealed multiresistance in one of two isolates. Antimicrobial treatment was modified according to diagnostic results in 11 of 31 patients (36%) with potentially pathogenic microorganisms. In patients who underwent a repeat investigation after 72 hrs, 24% of the initially present and potentially pathogenic microorganisms persisted. Inappropriate initial antimicrobial therapy was associated significantly with bacterial persistence (p < .002).

CONCLUSIONS

Considering the diversity of microbial pathogens and the resistance rates especially to S. pneumoniae in this patient population, antimicrobial treatment should be based on the constant study of local microbial and susceptibility patterns along with routine microbial investigation of the individual patient.

Airway inflammation and bronchial microbial patterns in patients with stable chronic obstructive pulmonary disease

The effect of bacterial colonization of the bronchi on the progress of airflow limitation is not well known. Therefore, the pattern of airway inflammation in smokers and patients with stable chronic obstructive pulmonary disease (COPD) and its relation to bronchial microbial colonization was assessed. Eight nonsmoking and 18 smoking controls as well as 52 patients with COPD (28 mild, 11 moderate and 13 severe) were studied. All subjects were investigated by means of flexible bronchoscopy including protected specimen brush and bronchoalveolar lavage (BAL) sampling. Differential cell counts, cytokine (interleukin (IL)-1beta, IL-6, IL-8, IL-10 and tumour necrosis factor-alpha(TNF-alpha) concentrations and microbial patterns were determined in BAL fluid. Forced expiratory volume in one second (FEV1) % of the predicted value was inversely correlated with pack-yrs of cigarette smoking (r=-0.47, p<0.0001), the percentage of neutrophil (p=-0.56, p<0.0001) and IL-6 (p=-0.37, p=0.01) and IL-8 concentration (p=-0.43, p=0.004) in BAL fluid. Accordingly, pk-yrs of cigarette smoking (p=0.39, p=0.01) and IL-8 (p=0.69, p<0.0001) and TNFalpha (p=0.4, p<0.005) were positively correlated with the percentage of neutrophils in BAL fluid. Smoking controls and COPD patients were mainly colonized in the bronchial tree (33%) by community endogenous potentially pathogenic micro-organisms (PPMs). Colonization rates and patterns of PPMs were not affected by severity of airflow obstruction. The presence of PPMs was significantly associated with higher percentages of neutrophils (33.2+/-10.4% versus 10.1+/-3.5%, p=0.02) and TNF-alpha concentration (29.9+/-10.8 versus 6.3+/-2.1 pg x mL(-1), p=0.01) in BAL fluid. In conclusion, bronchial neutrophilia is a key inflammatory pattern in chronic obstructive pulmonary disease patients. Bronchial colonization with potentially pathogenic micro-organisms may represent an independent stimulus for additional airway inflammation.

Bronchial microbial patterns in severe exacerbations of chronic obstructive pulmonary disease (COPD) requiring mechanical ventilation

We carried out a comprehensive microbiological study of the upper and lower airways in patients with severe exacerbations of chronic obstructive pulmonary disease (COPD) requiring mechanical ventilation in order to describe microbial patterns and analyze their clinical significance. Quantitative cultures of tracheobronchial aspirates (TBAs), bronchoscopically retrieved protected specimen brush (PSB) and bronchoalveolar lavage fluid (BALF) at admission to the ICU and after 72 h, as well as serology for bacteria and respiratory viruses were performed. Fifty patients (mean age 68 +/- 8, 46 males) were studied prospectively. Potentially pathogenic microorganisms (PPMs) and/or a positive serology were present in 36 of 50 (72%) patients, including 12 (33%) polymicrobial cases. Only six (12%) had no pathogen in any sample in the absence of antimicrobial pretreatment. Microbial patterns corresponded to community-acquired pathogens (Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis) in 19 of 34 (56%) and to gram-negative enteric bacilli (GNEB), Pseudomonas, and Stenotrophomonas spp. in 15 of 34 (44%) of isolates. Chlamydia pneumoniae and respiratory viruses were found in 18% and 16% of investigations, respectively. Repeated investigation after 72 h in 19 patients with PPMs in the initial investigation revealed eradication of virtually all isolates of community-acquired pathogens and GNEB but persistence of three of five Pseudomonas spp. and both Stenotrophomonas spp. as well as the emergence of new GNEB, Pseudomonas and Stenotrophomonas spp. Clinical parameters neither predicted the presence of PPMs nor of GNEB and Pseudomonas/Stenotrophomonas spp. Nevertheless, severe pneumonia attributable to initially isolated pathogens occurred in two patients with severe COPD exacerbation. We conclude that pathogens were more frequently present than previously reported. The rate of GNEB and Pseudomonas/Stenotrophomonas spp. isolates was high. The presence of pathogens was clinically unpredictable. Thus, in this population of patients with severe exacerbations of COPD, it may be advisable to obtain respiratory samples and to treat according to diagnostic results. Further studies are warranted to clarify this issue.

Community-acquired pneumonia in the elderly. Clinical and nutritional aspects

Community-acquired pneumonia (CAP) in the elderly has a different clinical presentation than CAP in other age groups. Confusion, alteration of functional physical capacity, and decompensation of underlying illnesses may appear as unique manifestations. Malnutrition is also an associated feature of CAP in this population. We undertook a study to assess the clinical and nutritional aspects of CAP requiring hospitalization in elderly patients (over 65 yr of age). One hundred and one patients with pneumonia, consecutively admitted to a 1,000-bed teaching hospital over an 8-mo period, were studied (age: 78 +/- 8 yr, mean +/- SD). Nutritional aspects and the mental status of patients with pneumonia were compared with those of a control population (n = 101) matched for gender, age, and date of hospitalization. The main symptoms were dyspnea (n = 71), cough (n = 67), and fever (n = 64). The association of these symptoms with CAP was observed in only 32 patients. The most common associated conditions were cardiac disease (n = 38) and chronic obstructive pulmonary disease (COPD) (n = 30). Seventy-seven (76%) episodes of pneumonia were clinically classified as typical and 24 as atypical. There was no association between the type of isolated microorganism and the clinical presentation of CAP, except for pleuritic chest pain, which was more common in pneumonia episodes caused by classical microorganisms (p = 0.02). This was confirmed by a multivariate analysis (relative risk [RR] = 11; 95% confidence interval [CI]: 1.7 to 65; p = 0.0099). The prevalence of chronic dementia was similar in the pneumonia cohort (n = 25) and control group (n = 18) (p = 0.22). However, delirium or acute confusion were significantly more frequent in the pneumonia cohort than in controls (45 versus 29 episodes; p = 0.019). Only 16 patients with pneumonia were considered to be well nourished, as compared with 47 control patients (p = 0.001). Kwashiorkor-like malnutrition was the predominant type of malnutrition (n = 65; 70%) in the pneumonia patients as compared with the control patients (n = 31; 31%) (p = 0.001). The observed mortality was 26% (n = 26). Pleuritic chest pain is the only clinical symptom that can guide an empiric therapeutic strategy in CAP (typical versus atypical pneumonia). Both delirium and malnutrition were very common clinical manifestations of CAP in our study population.

Bacterial colonization of distal airways in healthy subjects and chronic lung disease: a bronchoscopic study

In contrast to the healthy population, distal airway bacterial colonization may occur in patients with chronic lung diseases, who often have altered pulmonary defences. However, the information dealing with this issue is insufficient and is based mainly on nonspecific samples, such as sputum cultures. Using quantitative cultures of bronchoscopic protected specimen brush (PSB) and bronchoalveolar lavage (BAL) samples, we studied the bacterial colonization of distal airways in 16 healthy subjects, 33 patients with bronchogenic carcinoma, 18 with chronic obstructive pulmonary disease (COPD), 17 with bronchiectasis, and 32 with a long-term tracheostomy due to laryngeal carcinoma. All patients were without exacerbation, and free from antibiotic treatment at least 1 month before the study protocol. Thresholds for quantitative cultures to define colonization were > or = 10(2) colony-forming units (cfu) x mL(-1) for PSB and > or = 10(3) cfu x mL(-1) for BAL. Only one healthy subject was colonized by a potential pathogenic microorganism (PPM) (Staphylococcus aureus 4x10(2) cfu x mL(-1) in a PSB culture). Colonization was observed in 14 (42%) bronchogenic carcinoma patients (19 non-PPMs, and 10 PPMs); in 15 (83%) COPD patients (22 non-PPMs and 7 PPMs); in 15 (88%) bronchiectasis patients (20 non-PPMs and 13 PPMs); and in 15 (47%) long-term tracheostomy patients (5 non-PPMs and 13 PPMs). The two most frequent non-PPMs isolated in all groups studied were Streptococcus viridans and Neisseria spp. Haemophilus spp., Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis were the most frequent PPMs isolated in bronchogenic carcinoma, COPD, bronchiectasis and long-term tracheostomized patients, respectively. Pseudomonas aeruginosa colonization was infrequent in all the groups. Our results show that distal airway bacterial colonization is a frequent feature in stable patients with chronic lung diseases and also in patients with long-term tracheostomy. However, the pattern of colonization differs among groups studied. The knowledge of different colonization patterns may be important for future antibiotic prophylactic strategies and for the empirical antibiotic regimens when exacerbations occur in these patients.

Stomach as a source of colonization of the respiratory tract during mechanical ventilation: association with ventilator-associated pneumonia

The aetiopathogenesis of ventilator-associated pneumonia (VAP) requires abnormal oropharyngeal and gastric colonization and the further aspiration of their contents to the lower airways. VAP develops easily if aspiration or inoculation of microorganisms occur in patients with artificial airways, in whom mechanical, cellular and/or humoral defences are altered. Well-known risk factors for gastric colonization include: alterations in gastric juice secretion; alkalinization of gastric contents; administration of enteral nutrition; and the presence of bilirubin. However, the role of the colonized gastric reservoir in the development of VAP remains debatable. Evidence in favour of the role of the stomach in the development of VAP comes mainly from randomized, controlled trials of selective gut decontamination and stress ulcer prophylaxis in the intensive care unit (ICU), in which reducing the bacterial burden of the stomach decreases the incidence of nosocomial respiratory infections. However, at least three studies of flora have found an absence of stomach origin of pneumonia occurring during mechanical ventilation. Prophylactic measures suggested to prevent VAP in relation to the gastric reservoir include: treatment for stress ulcers with sucralfate; prevention of duodenal reflux with metoclopramide; reduction of gastric burden and bacterial translocation by selective digestive decontamination; acidification of enteral feeding; and jejunal feeding. Gastro-oesophageal reflux can be prevented by using small bore nasogastric tubes and jejunal feeding. The aspiration of gastric contents can be reduced by positioning patients in a semirecumbent position, checking the patency of the tube cuff, and aspiration of subglottic secretions. The role of the stomach as a reservoir for microorganisms causing ventilator-associated pneumonia is still controversial but despite the debate, there is major evidence in the literature in favour of the gastric origin of part of these pulmonary infections.

Markers of ventilator-associated pneumonia

The diagnosis of ventilator-associated pneumonia (VAP) is difficult for several reasons. Firstly, clinical markers show a large percentage of false-positive and false-negative results. Secondly, microbiological diagnosis based on quantitative cultures of protected specimen brush (PSB), bronchoalveolar lavage (BAL), and endotracheal aspirates also present false-positive and false-negative results. Furthermore, definite results are delayed for 48-72 hours. For all these reasons it would be an advantage to have a biological marker of ventilator-associated pneumonia in clinical practice. Since clinical features of pneumonia in mechanically ventilated patients are neither specific nor sensitive, rapid markers of pneumonia might be of great assistance to the clinician in deciding whether to start an empiric antibiotic regimen. A marker of ventilator-associated pneumonia could be a rapid alternative diagnostic method which permits the definite diagnosis of pneumonia. Accordingly, specific markers of VAP, namely the presence of intracellular microorganisms, the detection of elastin fibres, the antibody-coated bacteria test, the level of endotoxin in bronchoalveolar lavage fluid, the local production of interleukin-8, the levels of lactate dehydrogenase, and decreased surfactant protein A, may be important as they can provide a rapid diagnosis of VAP. Among the markers alluded to above, the search for intracellular bacteria in polymorphonuclear leukocytes or macrophages is the most widely validated technique with an excellent specificity, provided that prior antibiotics are not given. However, this technique has its own limitations; it requires a considerable time effort for the microbiologist, and also compels the performance of BAL, a technique not always harmless to the patient.

The role of the gastric reservoir in ventilator-associated pneumonia

Ventilator-associated pneumonia (VAP) is a common complication of mechanical ventilation with an incidence ranging from 9-70% and averaging around 25%. The pathogenesis of VAP requires abnormal oropharyngeal and gastric colonisation and then aspiration of these contents into the lower airways. Another co-existing mechanism could be direct oropharyngeal or lower airways inoculation of microorganisms through contaminated respiratory therapy equipment. Ventilator-associated pneumonia develops easily if aspiration or inoculation of microorganisms occur in patients with artificial airways and in whom mechanical, cellular and/or humoral defences are altered. Both host factors and treatments may alter pulmonary defence mechanisms; these too may contribute to the development of VAP. An alternative mechanism to explain VAP is bacterial translocation, although this mechanism is still under investigation. Figure 1 illustrates a schema of the pathogenesis of VAP. In this paper we review the possible role of the gastric reservoir in the aetiology of VAP, emphasising the following issues: 1. Risk factors for gastric colonisation 2. Clinical evidence of gastric aspiration to the lower airways in mechanically ventilated patients 3. Clinical evidence and controversies surrounding the role of the gastric reservoir in ventilator-associated pneumonia 4. The role of bacterial translocation as a mechanism for the development of VAP 5. A summary of prophylactic measures.