Safety of Bronchoalveolar Lavage in Hematological Patients with Thrombocytopenia. A Retrospective Cohort Study

Background

Hospitalized hematological patients often require bronchoalveolar lavage (BAL). Scarce evidence exists regarding the potential risks in patients with very severe thrombocytopenia (VST).

Methods

This retrospective-cohort study included adult hematological in-patients with VST, defined as platelets<20x103/μL, undergoing BAL during 2012-2021. Mechanically ventilated patients or those with known active bleeding were excluded. Primary outcomes included major bleeding halting the BAL or deemed significant by the treating physician, need for any respiratory support other than low flow O2, or death within 24 hours. Any other bleedings were recorded as secondary outcomes.

Results

Of the 507 patients included in the final analysis, the 281 patients with VST had lower hemoglobin (Md=0.3, p=0.003), longer prothrombin-time (Md=0.7s, p=0.025), higher chances of preprocedural platelet transfusion (RR 3.68, 95%CI [2.86,4.73]), and only one primary-outcome event (death of septic shock 21h postprocedurally) - compared with 3 (1.3%) events (two bleedings halting procedure and one need for non-invasive-ventilation) in patients with platelets ≥20x103/μL (p=0.219). The risk of minor spontaneously resolved bleeding was higher (RR=3.217, 95% CI [0.919,11.262]) in patients with VST (4.3% vs 1.3%, p=0.051). No association was found between the complications recorded and preprocedural platelets, age, aPTT, P.T., hematological status, or platelet transfusion.

Conclusions

This data suggests BAL to be safe even when platelet counts are <20x103/μL.

Combining reservoir mask oxygenation with high-flow nasal cannula in the treatment of hypoxemic respiratory failure among patients with COVID-19 pneumonia: a retrospective cohort study

BACKGROUND

Concerns regarding positive-pressure-ventilation for the treatment of coronavirus disease 2019 (COVID-19) hypoxemia led the search for alternative oxygenation techniques. This study aimed to assess one such method, dual oxygenation, i.e., the addition of a reservoir mask (RM) on top of a high-flow nasal cannula (HFNC).

METHODS

In this retrospective cohort study, the records of all patients hospitalized with COVID-19 during 2020-2022 were reviewed. Patients over the age of 18 years with hypoxemia necessitating HFNC were included. Exclusion criteria were positive-pressure-ventilation for any indication other than hypoxemic respiratory failure, transfer to another facility while still on HFNC and "do-not-intubate/resuscitate" orders. The primary outcome was mortality within 30 days from the first application of HFNC. Secondary outcomes were intubation and admission to the intensive care unit.

RESULTS

Of 659 patients included in the final analysis, 316 were treated with dual oxygenation and 343 with HFNC alone. Propensity for treatment was estimated based on background diagnoses, laboratories and vital signs upon admission, gender and glucocorticoid dose. Inverse probability of treatment weighted regression including age, body mass index, Sequential Organ Failure Assessment (SOFA) score and respiratory rate oxygenation index showed treatment with dual oxygenation to be associated with lower 30-day mortality (adjusted hazard ratio, 0.615; 95% confidence interval, 0.469-0.809). Differences in the secondary outcomes did not reach statistical significance.

CONCLUSIONS

Our study suggests that the addition of RM on top of HFNC may be associated with decreased mortality in patients with severe COVID-19 hypoxemia.

An unexpected diagnosis of a 57-year-old women with migratory pulmonary infiltrates

A 57-year-old female presented with sudden shortness of breath and migratory pulmonary infiltrates on imaging, which corresponds with a diagnosis of cryptogenic organizing pneumonia. Initial treatment with corticosteroids showed only mild improvement during follow-up. BAL was performed and revealed diffuse alveolar hemorrhage. Immune testing showed positive P-ANCA with positive MPO, leading to a diagnosis of microscopic polyangiitis.

The diagnostic value of nasal microbiota and clinical parameters in a multi-parametric prediction model to differentiate bacterial versus viral infections in lower respiratory tract infections

Background

The ability to accurately distinguish bacterial from viral infection would help clinicians better target antimicrobial therapy during suspected lower respiratory tract infections (LRTI). Although technological developments make it feasible to rapidly generate patient-specific microbiota profiles, evidence is required to show the clinical value of using microbiota data for infection diagnosis. In this study, we investigated whether adding nasal cavity microbiota profiles to readily available clinical information could improve machine learning classifiers to distinguish bacterial from viral infection in patients with LRTI.

Results

Various multi-parametric Random Forests classifiers were evaluated on the clinical and microbiota data of 293 LRTI patients for their prediction accuracies to differentiate bacterial from viral infection. The most predictive variable was C-reactive protein (CRP). We observed a marginal prediction improvement when 7 most prevalent nasal microbiota genera were added to the CRP model. In contrast, adding three clinical variables, absolute neutrophil count, consolidation on X-ray, and age group to the CRP model significantly improved the prediction. The best model correctly predicted 85% of the ‘bacterial’ patients and 82% of the ‘viral’ patients using 13 clinical and 3 nasal cavity microbiota genera (Staphylococcus, Moraxella, and Streptococcus).

Conclusions

We developed high-accuracy multi-parametric machine learning classifiers to differentiate bacterial from viral infections in LRTI patients of various ages. We demonstrated the predictive value of four easy-to-collect clinical variables which facilitate personalized and accurate clinical decision-making. We observed that nasal cavity microbiota correlate with the clinical variables and thus may not add significant value to diagnostic algorithms that aim to differentiate bacterial from viral infections.

Pulmonary vasculopathy in explanted lungs from patients with interstitial lung disease undergoing lung transplantation

BACKGROUND

Pulmonary hypertension (PH) causes increased morbidity and mortality in patients with interstitial lung diseases (ILD). Classification schemes, while well-characterised for the vasculopathy of idiopathic PH, have been applied, unchallenged, to ILD-related PH. We evaluated pulmonary arterial histopathology in explanted human lung tissue from patients who were transplanted for advanced fibrotic ILD.

METHODS

Lung explants from 38 adult patients who underwent lung transplantation were included. Patients were divided into three groups: none, mild/moderate and severe PH by mean pulmonary artery pressure (mPAP) measured at pre lung transplantation right heart catheterisation (RHC). Grading of pulmonary vasculopathy according to Heath and Edwards scheme, and prelung transplantation evaluation data were compared between the groups.

RESULTS

38 patients with fibrotic ILDs were included, the majority (21) with idiopathic pulmonary fibrosis. Of the 38 patients, 18 had severe PH, 13 had mild/moderate PH and 7 had no PH by RHC. 16 of 38 patients had severe pulmonary arterial vasculopathy including vascular occlusion with intimal fibrosis and/or plexiform lesions. There were no correlations between mPAP and lung diffusion with the severity of pulmonary arterial pathological grade (Spearman's rho=0.14, p=0.34, rho=0.11, p=0.49, respectively).

CONCLUSIONS

Patients with end stage ILD had severe pulmonary arterial vasculopathy in their explanted lungs irrespective of the presence and/or severity of PH as measured by RHC. These findings suggest that advanced pulmonary arterial vasculopathy is common in patients with advanced fibrotic ILD and may develop prior to the clinical detection of PH by RHC.

Dyspnea With Unilateral Pulmonary Ground Glass Opacities and Cavitary Lesions

CASE PRESENTATION

A 62-year-old man presented with a 3-month history of shortness of breath and a dry cough. He had a medical history of hypertension (without use of angiotensin-converting enzyme inhibitors), hyperlipidemia, depression, and 10-pack-years of cigarette smoking several decades ago. He was a limousine driver and denied any history of occupational high-risk exposures. The patient denied significant weight gain or weight loss, night sweats, fevers, hemoptysis, chest pain, or palpitations. He had a normal physical examination. Pulmonary function studies with a hemoglobin level of 12.9 gm/dL revealed normal spirometry, normal lung volumes, and moderately low diffusion capacity (56% of predicted). A 6-minute walk test showed mild desaturation (97% to 92% after 432 m). Stress echo revealed ejection fraction of 60% with no regional wall motion abnormalities, no evidence of impaired diastolic filling, estimated peak pulmonary artery pressure 35 to 40 mm Hg, and no valvular abnormalities with desaturation to 87% during the test. Extensive rheumatologic, infectious disease, and hypercoagulability workup were unremarkable. BAL was negative for malignancy, infection, or eosinophilic lung disease.

Clinical predictors and explant lung pathology of acute exacerbation of idiopathic pulmonary fibrosis

Background

Idiopathic pulmonary fibrosis (IPF) is characterised by constant threat of acute exacerbation of IPF (AE-IPF). It would be significant to identify risk factors of AE-IPF. We sought to determine the prognostic value of lung transplantation candidacy testing for AE-IPF and describe explant pathology of recipients with and without AE-IPF before lung transplantation.

Methods

Retrospective cohort study of 89 IPF patients listed for lung transplantation. Data included pulmonary function testing, echocardiography, right heart catheterisation, imaging, oesophageal pH/manometry and blood tests. Explanted tissue was evaluated by pulmonary pathologists and correlated to computed tomography (CT) findings.

Results

Out of 89 patients with IPF, 52 were transplanted during stable IPF and 37 had AE-IPF before transplantation (n=28) or death (n=9). There were no substantial differences in candidacy testing with and without AE-IPF. AE-IPF had higher rate of decline of forced vital capacity (FVC) (21±22% versus 4.8±14%, p=0.00019). FVC decline of >15% had a hazard ratio of 7.2 for developing AE-IPF compared to FVC decline of <5% (p=0.004). AE-IPF had more secondary diverse histopathology (82% versus 29%, p<0.0001) beyond diffuse alveolar damage. There was no correlation between ground-glass opacities (GGO) on chest CT at any point to development of AE-IPF (p=0.077), but GGO during AE-IPF predicted secondary pathological process beyond diffuse alveolar damage.

Conclusions

Lung transplantation candidacy testing including reflux studies did not predict AE-IPF besides FVC absolute decline. CT did not predict clinical or pathological AE-IPF. Secondary diverse lung pathology beyond diffuse alveolar damage was present in most AE-IPF, but not in stable IPF.

Transplant candidacy testing fails to predict acute exacerbation of IPF besides FVC absolute decline. Patients transplanted during acute exacerbation of IPF reveal multiple secondary lung histopathological processes beyond the expected DAD.https://bit.ly/3e1CPjO

Acute exacerbations of COPD versus IPF in patients with combined pulmonary fibrosis and emphysema

Rationale

Patients with combined pulmonary fibrosis and emphysema (CPFE) may develop acute exacerbations of IPF (AE-IPF) or COPD (AE-COPD). The incidence and the characteristics of exacerbations in patients with CPFE (e.g., COPD vs IPF) have not been well described.

Objectives

To compare the incidence and rate of exacerbations in patients with CPFE vs. IPF and evaluate their effect on clinical outcomes.

Methods

Comprehensive clinical data from CPFE and IPF patients were retrospectively reviewed. Baseline characteristics including lung function data, oxygen requirements, and pulmonary hemodynamics, were collected. Acute exacerbation events in both groups were defined clinically and radiographically. In the CPFE group, two patterns of exacerbations were identified. AE-COPD was defined clinically by symptoms of severe airflow obstruction causing respiratory failure and requiring hospitalization. Radiographic data were also defined based on previously published literature. AE-IPF was defined clinically as an acute hypoxic respiratory failure, requiring hospitalization and treatment with high dose corticosteroids. Radiographically, patients had to have a change in baseline imaging including presence of ground-glass opacities, interlobular septal thickening or new consolidations; that is not fully explained by other etiologies.

Results

Eighty-five CPFE patients were retrospectively compared to 112 IPF patients. Of 112 patients with IPF; 45 had AE-IPF preceding lung transplant (40.18%) compared to 12 patients in the CPFE group (14.1%) (p < 0.05). 10 patients in the CPFE group experienced AE-COPD (11.7%). Patients with AE-IPF had higher mortality and more likely required mechanical ventilation and extracorporeal membrane oxygenation (ECMO) compared to patients with AE-COPD, whether their underlying disease was IPF or CPFE.

Conclusions

CPFE patients may experience either AE-IPF or AE-COPD. Patients with CPFE and AE-COPD had better outcomes, requiring less intensive therapy compared to patients with AE-IPF regardless if underlying CPFE or IPF was present. These data suggest that the type of acute exacerbation, AE-COPD vs AE-IPF, has important implications for the treatment and prognosis of patients with CPFE.

Electrical stimulation of the whole hypoglossal nerve in patients with obstructive sleep apnea

PURPOSE

Electrical stimulation of the whole hypoglossal nerve (HGp-ES) has been demonstrated to enlarge the pharynx and improve pharyngeal stability and patency to airflow in all animals studied, but not in humans. The present study was undertaken to better understand the effect of HGp-ES on the human pharynx.

METHODS

Eight patients with obstructive sleep apnea who had implanted stimulators with electrodes positioned proximally on the main truck of the hypoglossus were studied under propofol sedation. Pharyngoscopy and air flow measurements at multiple levels of continuous positive airway pressure (CPAP) were performed before and during Hgp-ES.

RESULTS

HGp-ES that activates both tongue protrusors and retractors narrowed the pharyngeal lumen at the site of collapse (velopharynx in all subjects) from 1.38 ± 0.79 to 0.75 ± 0.44 cm², p < 0.05 (measured at mid-range of CPAP levels) and lowered airflow (from 8.88 ± 2.08 to 6.69 ± 3.51 l/min, p < 0.05). Changes in critical pressure (Pcrit) and velopharyngeal compliance were not significant, but oropharyngeal compliance decreased (from 0.43 ± 0.18 to 0.32 ± 0.13 cm²/cmH2O, p < 0.05). No correlation was found between the pattern of change in luminal shape (determined as the ratio of a-p vs. lateral diameter when lowering CPAP) or changes in cross-sectional area and airflow during Hgp-ES.

CONCLUSIONS

Our findings indicate that human retractors dominate when stimulated together with the protrusors during HGp-ES. While co-activation of retractors may be beneficial, it should be limited. We speculate that exercises that augment protrusor force may improve the response to hypoglossal stimulation. The exclusion of patients with concentric pharyngeal obstruction should be re-evaluated.

Antibiotic misuse in respiratory tract infections in children and adults-a prospective, multicentre study (TAILORED Treatment)

Respiratory tract infections (RTI) are more commonly caused by viral pathogens in children than in adults. Surprisingly, little is known about antibiotic use in children as compared to adults with RTI. This prospective study aimed to determine antibiotic misuse in children and adults with RTI, using an expert panel reference standard, in order to prioritise the target age population for antibiotic stewardship interventions. We recruited children and adults who presented at the emergency department or were hospitalised with clinical presentation of RTI in The Netherlands and Israel. A panel of three experienced physicians adjudicated a reference standard diagnosis (i.e. bacterial or viral infection) for all the patients using all available clinical and laboratory information, including a 28-day follow-up assessment. The cohort included 284 children and 232 adults with RTI (median age, 1.3 years and 64.5 years, respectively). The proportion of viral infections was larger in children than in adults (209(74%) versus 89(38%), p < 0.001). In case of viral RTI, antibiotics were prescribed (i.e. overuse) less frequently in children than in adults (77/209 (37%) versus 74/89 (83%), p < 0.001). One (1%) child and three (2%) adults with bacterial infection were not treated with antibiotics (i.e. underuse); all were mild cases. This international, prospective study confirms major antibiotic overuse in patients with RTI. Viral infection is more common in children, but antibiotic overuse is more frequent in adults with viral RTI. Together, these findings support the need for effective interventions to decrease antibiotic overuse in RTI patients of all ages.

Alteration in upper airway dilator muscle coactivation during sleep: comparison of patients with obstructive sleep apnea and healthy subjects

In patients with obstructive sleep apnea (OSA), substantial increases in genioglossus (GG) activity during hypopneas/apneas usually fail to restore normal airflow. We have previously suggested that sleep-induced alteration in tongue muscle coordination may explain this finding, as retractor muscle coactivation was reduced during sleep compared with wakefulness. The present study was undertaken to evaluate whether these alterations in dilator muscle activation during sleep play a role in the pathogenesis of OSA and whether coactivation of additional peripharyngeal muscles (non-GG muscles: styloglossus, geniohyoid, sternohyoid, and sternocleidomastoid) is also impaired during sleep. We compared GG and non-GG muscle electromyographic (EMG) activity in 8 patients with OSA and 12 healthy subjects during wakefulness while breathing through inspiratory resistors with the activity observed during sleep toward the end of flow limitation, before arousal, at equivalent esophageal pressures. During wakefulness, resistive breathing triggered increases in both GG and non-GG muscle activity. During sleep, flow limitation was associated with increases in GG-EMG that reached, on average, >2-fold the level observed while awake. In contrast, EMGs of the non-GG muscles, recorded simultaneously, reached, on average, only ~2/3 the wakefulness level. We conclude that during sleep GG activity may increase to levels that substantially exceed those sufficient to prevent pharyngeal collapse during wakefulness, whereas other peripharyngeal muscles do not coactivate during sleep in both patients with OSA and healthy subjects. We speculate that upper airway muscle dyssynchrony during sleep may explain why GG-EMG activation fails to alleviate flow limitation and stabilize airway patency during sleep.

NEW & NOTEWORTHY Pharyngeal obstruction during sleep may trigger genioglossus activity to levels substantially exceeding those observed during wakefulness, without ameliorating flow limitation. In contrast, other peripharyngeal muscles exhibit a much lower activity during sleep in both patients with obstructive sleep apnea and healthy subjects. Coordinated muscular synergy stabilizes the pharynx despite relatively low activity while awake, yet even higher genioglossal activity allows the pharynx to obstruct when simultaneous activity of other dilator muscles is inadequate during sleep.

Alteration in upper airway dilator muscle coactivation during sleep: comparison of patients with obstructive sleep apnea and healthy subjects

In patients with obstructive sleep apnea (OSA), substantial increases in genioglossus (GG) activity during hypopneas/apneas usually fail to restore normal airflow. We have previously suggested that sleep-induced alteration in tongue muscle coordination may explain this finding, as retractor muscle coactivation was reduced during sleep compared with wakefulness. The present study was undertaken to evaluate whether these alterations in dilator muscle activation during sleep play a role in the pathogenesis of OSA and whether coactivation of additional peripharyngeal muscles (non-GG muscles: styloglossus, geniohyoid, sternohyoid, and sternocleidomastoid) is also impaired during sleep. We compared GG and non-GG muscle electromyographic (EMG) activity in 8 patients with OSA and 12 healthy subjects during wakefulness while breathing through inspiratory resistors with the activity observed during sleep toward the end of flow limitation, before arousal, at equivalent esophageal pressures. During wakefulness, resistive breathing triggered increases in both GG and non-GG muscle activity. During sleep, flow limitation was associated with increases in GG-EMG that reached, on average, >2-fold the level observed while awake. In contrast, EMGs of the non-GG muscles, recorded simultaneously, reached, on average, only ~2/3 the wakefulness level. We conclude that during sleep GG activity may increase to levels that substantially exceed those sufficient to prevent pharyngeal collapse during wakefulness, whereas other peripharyngeal muscles do not coactivate during sleep in both patients with OSA and healthy subjects. We speculate that upper airway muscle dyssynchrony during sleep may explain why GG-EMG activation fails to alleviate flow limitation and stabilize airway patency during sleep. NEW & NOTEWORTHY Pharyngeal obstruction during sleep may trigger genioglossus activity to levels substantially exceeding those observed during wakefulness, without ameliorating flow limitation. In contrast, other peripharyngeal muscles exhibit a much lower activity during sleep in both patients with obstructive sleep apnea and healthy subjects. Coordinated muscular synergy stabilizes the pharynx despite relatively low activity while awake, yet even higher genioglossal activity allows the pharynx to obstruct when simultaneous activity of other dilator muscles is inadequate during sleep.

A novel host-protein assay outperforms routine parameters for distinguishing between bacterial and viral lower respiratory tract infections

Bacterial and viral lower respiratory tract infections (LRTIs) are often clinically indistinguishable, leading to antibiotic overuse. We compared the diagnostic accuracy of a new assay that combines 3 host-biomarkers (TRAIL, IP-10, CRP) with parameters in routine use to distinguish bacterial from viral LRTIs. Study cohort included 184 potentially eligible pediatric and adult patients. Reference standard diagnosis was based on adjudication by an expert panel following comprehensive clinical and laboratory investigation (including respiratory PCRs). Experts were blinded to assay results and assay performers were blinded to reference standard outcomes. Evaluated cohort included 88 bacterial and 36 viral patients (23 did not fulfill inclusion criteria; 37 had indeterminate reference standard outcome). Assay distinguished bacterial from viral LRTI patients with sensitivity of 0.93±0.06 and specificity of 0.91±0.09, outperforming routine parameters, including WBC, CRP and chest x-ray signs. These findings support the assay's potential to help clinicians avoid missing bacterial LRTIs or overusing antibiotics.

[A PROSPECTIVE STUDY TO INCREASE THE AWARENESS OF VENOUS THROMBOEMBOLISM PROPHYLAXIS IN INTERNAL MEDICINE WARDS]

INTRODUCTION

Venous thromboembolism (VTE) events are a significant risk factor for morbidity and mortality among hospitalized patients and 50-75% of the events occur in internal medicine wards. Despite the proven efficiency of prophylactic treatments, their usage in hospitals is underutilized. Multiple studies have shown that only 30-50% of the high risk VTE patients are treated prophylactically. Interventional programs were shown to significantly increase the awareness and hence, the percent of patients treated. However, there are no official guidelines for prophylaxis implementation among hospital personnel in Israel.

METHODS

We conducted a prospective study of patients hospitalized in internal medicine wards to estimate the risk of VTE events and the prophylaxis rate. Patients were randomly selected and evaluated for VTE risk and treatment provided. During daily staff meetings on random sampling days, an open inquiry was conducted for each patient's management regarding VTE prophylaxis. This supervision was carried out for 3 consecutive months and 6 months later, to evaluate the implementation of the process.

RESULTS

A total of 205 patients were sampled during the study. During the first month, 35% of the patients with indications for prophylaxis were treated. This percent increased to 50% in the second month, 60% in the third, and to 86% after six months (p<0.0001).

CONCLUSIONS

The awareness of VTE prophylaxis was low, and only a third of the patients with indications for prophylaxis were treated. The awareness implementation was slow and incremental, and increased from 35% to 86%. We conclude that the supervision and training on VTE prophylaxis is efficient and essential.

Differential effects of respiratory and electrical stimulation-induced dilator muscle contraction on mechanical properties of the pharynx in the pig

Respiratory stimulation (RS) during sleep often fails to discontinue flow limitation, whereas electrical stimulation (ES) of the hypoglossus (HG) nerve frequently prevents obstruction. The present work compares the effects of RS and HG-ES on pharyngeal mechanics and the relative contribution of tongue muscles and thoracic forces to pharyngeal patency. We determined the pressure-area relationship of the collapsible segment of the pharynx in anesthetized pigs under the following three conditions: baseline (BL), RS induced by partial obstruction of the tracheostomy tube, and HG-ES. Parameters were obtained also after transection of the neck muscles and the trachea (NMT) and after additional bilateral HG transection (HGT). In addition, we measured the force produced by in situ isolated geniohyoid (GH) during RS and HG-ES. Intense RS was recognized by large negative intrathoracic pressures and triggered high phasic genioglossus and GH EMG activity. GH contraction produced during maximal RS less than a quarter of the force obtained during HG-ES. The major finding of the study was that RS and ES differed in the mechanism by which they stabilized the pharynx: RS lowered the pressure-area slope, i.e., reduced pharyngeal compliance (14.1 ± 2.9 to 9.2 ± 1.9 mm2/cmH2O, P < 0.01). HG-ES shifted the slope toward lower pressures, i.e., lowered the calculated extraluminal pressure (17.4 ± 5.8 to 9.2 ± 7.4 cmH2O, P < 0.01). Changes during RS and HG-ES were not affected by NMT, but the effect of RS decreased significantly after HGT. In conclusion, HG-ES and RS affect the pharyngeal site of collapse differently. Tongue muscle contraction contributes to pharyngeal stiffening during RS.

Widespread osteoblastic metastases and marked elevation of CA19-9 as a presentation of signet ring cell gastric carcinoma

Widespread osteoblastic metastases, as well as marked elevations of CA19-9 and carcino-embryonic antigen (CEA), are the initial manifestations of gastric signet ring cell carcinoma. CT Imaging revealed diffuse sclerotic metastases in the axial skeleton. It was only following gastric biopsy that the primary site of metastatic bone tumor was identified. Recent studies suggest that early diagnosis of cancer origin, including tumor molecular profiling, may dictate specific therapy, improve prognosis and increase patient survival rates.

Delayed Bleeding after Percutaneous Liver Biopsy

Percutaneous liver biopsy (PLB) is a common procedure in patients with liver disease. Bleeding after PLB is rare, with an incidence of 0.35%. Most bleeding complications present within 24 h after biopsy. A 56-year-old woman was admitted to our hospital due to severe and sudden right upper quadrant (RUQ) abdominal pain 10 days after ultrasound (US)-guided PLB. CT study revealed both intrahepatic and intraperitoneal bleeding, and Hb levels decreased by 3.2 g/dl within a few hours. Such a prolonged delay in PLB-related bleeding has not been previously described in the medical literature.

[SPONTANEOUS BACTERIAL EMPYEMA--A RARE BUT IMPORTANT COMPLICATION OF HEPATIC HYDROTHORAX IN CIRRHOTIC PATIENTS]

Spontaneous bacterial empyema, a complication of hepatic hydrothorax in cirrhotic patients, is a rare but nevertheless important medical entity. The diagnosis, treatment and prognosis of spontaneous bacterial empyema differs from the "usual" empyema, and avoiding proper diagnosis or treatment delay may have far reaching consequences. We report on a patient who was diagnosed in our department with spontaneous bacterial empyema, review the main current literature on the subject and elaborate on the specific therapeutic considerations related to the case management.

Asynchrony of lingual muscle recruitment during sleep in obstructive sleep apnea

Pharyngeal collapsibility during sleep increases primarily due to decline in dilator muscle activity. However, genioglossus EMG is known to increase during apneas and hypopneas, usually without reversing upper airway obstruction or inspiratory flow limitation. The present study was undertaken to test the hypothesis that intense activation of the genioglossus fails to prevent pharyngeal obstruction during sleep, and to evaluate if sleep-induced changes in tongue muscle coordination may be responsible for this phenomenon. We compared genioglossus and tongue retractors EMG activity in 13 obstructive sleep apnea (OSA) patients during wakefulness, while breathing through inspiratory resistors, to the activity observed at the end of apneas and hypopneas after 25 mg of brotizolam, before arousal, at equal esophageal pressure. During wakefulness, resistive breathing triggered increases in both genioglossus and retractor EMG. Activation of agonist tongue muscles differed considerably from that of the arm, as both genioglossus and retractors were activated similarly during all tongue movements. During sleep, flow limitation triggered increases in genioglossal EMG that could reach more than twofold the level observed while awake. In contrast, EMGs of the retractors reached less than half the wakefulness level. In sleeping OSA patients, genioglossal activity may increase during obstructed breathing to levels that exceed substantially those required to prevent pharyngeal collapse during wakefulness. In contrast, coactivation of retractors is deficient during sleep. These findings suggest that sleep-induced alteration in tongue muscle coordination may be responsible for the failure of high genioglossal EMG activity to alleviate flow limitation.

Evaluation of antioxidants: scope, limitations and relevance of assays

Peroxidation of lipids, particularly polyunsaturated fatty acid residues (PUFA) of phospholipids and cholesterol esters, is a process of marked implications: it shortens the shelf-life of food and drugs, it causes fragmentation of DNA, it damages cellular membranes and it promotes the genesis of many human diseases. Much effort is therefore devoted to a search for "potent antioxidants", both synthetic and from natural sources, mostly plants. This, in turn, requires a reliable, simple, preferably high throughput assay of the activity of alleged antioxidants. The most commonly used assays are based on measurements of the total antioxidant capacity (TAC) of a solution, as evaluated either by determining the rate of oxidation of the antioxidant or by measuring the protection of an easily determined indicator against oxidation by the antioxidants. The commonly used assays utilized for ranking antioxidants share three common problems: (i) They usually evaluate the effects of those antioxidants that quench free radicals, which constitute only a part of the body's antioxidative network, in which enzymes play the central role. (ii) Both the capacity and potency of antioxidants, as obtained by various methods, do not necessarily correlate with each other. (iii) Most estimates are based on methods conducted in solution and are therefore not necessarily relevant to processes that occur at the lipid-water interfaces in both membranes and micro emulsions (e.g. lipoproteins). Given this "state of art", many researchers, including us, try to develop a method based on the formation of hydroperoxides (LOOH) upon peroxidation of PUFA in lipoproteins or in model membranes, such as liposomes. In these systems, as well as in lipoproteins, the most apparent effect of antioxidants is prolongation of the lag time preceding the propagation of a free radical chain reaction. In fact, under certain conditions both water soluble antioxidants (e.g. vitamin C and urate) and the lipid soluble antioxidant tocopherol (vitamin E), promote or even induce peroxidation. Based on the published data, including our results, we conclude that terms such as 'antioxidative capacity' or 'antioxidative potency' are context-dependent. Furthermore, criteria of the efficacy of antioxidants based on oxidation in solution are not necessarily relevant to the effects of antioxidants on peroxidation in biological systems or model lipid assemblies, because the latter processes occur at water/lipid interfaces. We think that evaluation of antioxidants requires kinetic studies of the biomarker used and that the most relevant characteristic of 'oxidative stress' in the biological context is the kinetics of ex vivo peroxidation of lipids. We therefore propose studying the kinetics of lipid-peroxidation in the absence of the studied antioxidant and in its presence at different antioxidant concentrations. These protocols mean that antioxidants are assayed by methods commonly used to evaluate oxidative stress. The advantage of such evaluation is that it enables quantization of the antioxidants' efficacy in a model of relevance to biological systems. In view of the sensitivity of the lag time preceding peroxidation, we propose studying how much antioxidant is required to double the lag observed prior to rapid peroxidation. The latter quantity (C(2lag)) can be used to express the strength of antioxidants in the relevant system (e.g. LDL, serum or liposomes).

Implanted upper airway stimulation device for obstructive sleep apnea

OBJECTIVES/HYPOTHESIS

Previous feasibility studies have shown that electrical stimulation of the hypoglossal nerve can improve obstructive sleep apnea (OSA). The current study examined the safety and preliminary effectiveness of a second generation device, the Upper Airway Stimulation (UAS) system, and identified baseline predictors for therapy success.

STUDY DESIGN

Two consecutive open prospective studies.

METHODS

UAS systems were implanted in patients with moderate to severe OSA who failed or were intolerant of continuous positive airway pressure (CPAP). The study was conducted in 2 parts. In part 1, patients were enrolled with broad selection criteria. Apnea hypopnea index (AHI) was collected using laboratory-based polysomnography at preimplant and postimplant visits. Epworth Sleepiness Scale (ESS) and Functional Outcomes of Sleep Questionnaire (FOSQ) were also collected. In part 2, patients were enrolled using selection criteria derived from the experience in part 1.

RESULTS

In part 1, 20 of 22 enrolled patients (two exited the study) were examined for factors predictive of therapy response. Responders had both a body mass index ≤32 and AHI ≤50 (P < .05) and did not have complete concentric palatal collapse. Part 2 patients (n = 8) were selected using responder criteria and showed an improvement on AHI from baseline, from 38.9 ± 9.8 to 10.0 ± 11.0 (P < .01) at 6 months postimplant. Both ESS and FOSQ improved significantly in part 1 and 2 subjects.

CONCLUSIONS

The current study has demonstrated that therapy with upper airway stimulation is safe and efficacious in a select group of patients with moderate to severe OSA who cannot or will not use CPAP as primary treatment.

Parameters affecting pharyngeal response to genioglossus stimulation in sleep apnoea

Chronic stimulation of the hypoglossus nerve may provide a new treatment modality for obstructive sleep apnoea (OSA). In previous studies we observed large differences in response to stimulation of the genioglossus (GG). We hypothesised that both individual patient characteristics and the area of the GG stimulated are responsible for these differences. In the present study, we compared the response to GG electrical stimulation at the anterior area (GGa-ES), which activates the whole GG and the posterior area (GGp-ES), which activates preferentially the longitudinal fibres. Studies were performed in 14 propofol-sedated OSA patients. The parameters evaluated included cephalometry, pressure-flow relationship and pharyngeal shape and compliance assessed by pharyngoscopy. Compared with GGa-ES, GGp-ES resulted in significantly larger decreases in the critical value of end-expiratory pressure (P(crit)) (from 3.8 ± 2.2 to 2.9 ± 3.3 and -2.0 ± 3.9 cmH(2)O, respectively (p<0.001)). Both tongue size and velopharyngeal shape (anteroposterior to lateral ratio) correlated significantly with the decrease in P(crit) during GGp-ES (R = 0.53 and -0.66, respectively; p<0.05). In the patients with the larger tongue size (n = 7), the decrease in P(crit) reached 8.0 ± 2.2 cmH(2)O during GGp-ES. We conclude that directing stimulation to longitudinal fibres of the GG improves the flow-mechanical effect. In addition, patients with large tongues and narrow pharynx tend to respond better to GGp-ES.

[Sleep spindles in post traumatic stress disorder: significant importance of selective serotonin reuptake inhibitors]

BACKGROUND

Sleep spindles (SS) are conducted by the thalamus during sleep and have an inhibitory effect on information rising through the thalamus to the cortex, probably representing the mechanism called Arousal Inhibitory Mechanism. They appear during sleep stage 2 but also in stages 3, 4 and REM (Rapid Eye Movements). Patients with post traumatic stress disorder (PTSD) complain of insomnia, although objective studies have revealed that their sleep is deeper and their awakening threshold is higher. The relationships between PTSD or selective serotonin reuptake inhibitors (SSRI) to SS density are not described in the literature.

GOALS

This study aimed to examine the hypothesis that the higher awakening threshold reflects an active defense process which would be manifested in increased sleep spindles in patients with PTSD.

METHODS

A total of 15 PTSD patients (36.3 +/- 11.4 years) comprised the research group and 15 healthy students (27.3 +/- 2.18 years) comprised the control group. Participants underwent a polysomnography study in the sleep laboratory at 'Rambam' Hospital, Haifa, Israel.

RESULTS

There was no difference in the sleep spindles density per minute during stage 2 between the research group (2.54 +/- 1.14) and the control group (2.86 +/- 1.3). However, sleep spindles density was highly affected by selective serotonin reuptake inhibitors, such that PTSD patients treated with SSRI's had significantly higher spindles density than the remaining PTSD patients (3.25 +/- 1.1 vs 1.72 +/- 0.46, p=0.0044). Stage 2 was shorter in the research group (47% +/- 8.75%) compared to the control group (58% +/- 8.5%, p=0.0014), while stages 3, 4 were longer (32% +/- 8% vs 18% +/- 6.26%, p<0.001).

CONCLUSIONS

Sleep spindle density was generally not increased in patients with PTSD, thus other mechanisms are probably responsible for their stabilization of sleep. SSRI's were found to have an important role in spindles density, which supports a serotonergic mechanism in the stabilization of sleep, although it requires further research.

Multimodality exploration by an unsupervised projection pursuit neural network

Graphical inspection of multimodality is demonstrated using unsupervised lateral-inhibition neural networks. Three projection pursuit indexes are compared on low-dimensional simulated and real-world data: principal components, Legendre polynomial, and projection pursuit network.

Lipid peroxidation cannot be used as a universal criterion of oxidative stress

Oxidative stress is a term used to denote the imbalance between the concentrations of reactive oxygen and nitrogen species and the defense mechanisms of the body. Although it is generally accepted that such an imbalance plays a pivotal role in many pathologies, the term "oxidative stress" remains ill defined. In an attempt to evaluate the relationship between various assays of oxidative stress, we have analyzed the correlations between the results reported in those publications in which "oxidative stress" has been assayed by at least two methods. We found good correlations between the concentrations of several peroxidation products, including malondialdehyde, F2-Isoprostanes, lipid hydroperoxides, conjugated dienes, glutathione and protein carbonyls, but not with other criteria of "individual oxidative status" such as the concentration of antioxidants and products of DNA fragmentation (the "comet" assay). In light of these findings, we divide the assays used for evaluation of "oxidative stress" into the following three categories: (i) assays based on measuring the concentrations of oxidation products of lipids, proteins and DNA, as well as the concentrations of antioxidants, (ii) assays used to evaluate the oxidative and reductive capacity of biological fluids and (iii) assays used to evaluate the ex vivo susceptibility of lipids to oxidation upon their exposure to a source of free radicals. Our analyses demonstrate that oxidative stress cannot be defined in universal terms. Two results are of special interest:1.the commonly used criteria based on lipid peroxidation can not be regarded as a general estimate of the individual "oxidative status".2.the levels of antioxidants exhibit a non-monotonic relation with other criteria for oxidative stress. Further research is required to evaluate the significance of the latter finding.

Correlation of subjective pain experience with cerebral evoked responses to noxious thermal stimulations

The relationships between different parameters of the evoked cerebral response to noxious thermal stimulation, stimulus intensity, and subjective pain were investigated in seven normal human volunteers. The evoked response was characterized by late events: a small negative peak at 164--180 ms, followed by a high amplitude positive peak at 372--391 ms. The only correlation found in this study was between the amplitude of the positive component and the qualitative and quantitative aspects of the verbal report of pain. This was manifested by a linear trend of association: an increase in the evoked response amplitude was accompanied by an increase in the magnitude of the subjective sensation. The findings suggest that the evoked response to noxious heat reflects not a mere transduction of the physical parameters of the stimulus, but rather a complex interpretative action at the cerebral level.