Ahmad Husari

Critical Care Clinicians’ Knowledge of Evidence-Based Guidelines for Preventing Ventilator-Associated Pneumonia

BACKGROUND Ventilator-associated pneumonia is the most common hospital-acquired infection among patients receiving mechanical ventilation in an intensive care unit. Different initiatives for the prevention of ventilator-associated pneumonia have been developed and recommended. OBJECTIVE To evaluate knowledge of critical care providers (physicians, nurses, and respiratory therapists in the intensive care unit) about evidence-based guidelines for preventing ventilator-associated pneumonia. METHODS Ten physicians, 41 nurses, and 18 respiratory therapists working in the intensive care unit of a major tertiary care university hospital center completed an anonymous questionnaire on 9 nonpharmacological guidelines for prevention of ventilator-associated pneumonia. RESULTS The mean (SD) total scores of physicians, nurses, and respiratory therapists were 80.2% (11.4%), 78.1% (10.6%), and 80.5% (6%), respectively, with no significant differences between them. Furthermore, within each category of health care professionals, the scores of professionals with less than 5 years of intensive care experience did not differ significantly from the scores of professionals with more than 5 years of intensive care experience. CONCLUSIONS A health care delivery model that includes physicians, nurses, and respiratory therapists in the intensive care unit can result in an adequate level of knowledge on evidence-based nonpharmacological guidelines for the prevention of ventilator-associated pneumonia.

Changes in resistances of endotracheal tubes with reductions in the cross-sectional area.

Background and objectives: Partial obstruction of endotracheal tubes due to accumulation of secretions and mucus plugs can increase the tube resistance and subsequently impose increased resistive load on the patient. This study was performed to determine the changes in the resistance of endotracheal tubes of sizes 7.5, 8.0 and 8.5 mm with different degrees and locations of endotracheal tube narrowing. Methods: Reductions of 10%, 25%, 50% and 75% in the endotracheal tubes cross‐sectional areas were created at different sites along the axes of the tube connected to an artificial lung. While ventilating with a constant inspiratory flow, a 1 s end‐inspiratory occlusion manoeuvre was applied and the resulting plateau pressure was determined. The resistance was calculated as (peak airway pressure ‐ plateau pressure)/peak inspiratory flow. Results: Significant increases in the endotracheal tubes resistances were observed as the tubes cross‐sectional area reduction was increased from 25% to 50% and from 50% to 75% for the 7.5 mm endotracheal tube, from 25% to 50% for the 8.0 mm endotracheal tube, and from 50% to 75% for the 8.5 mm endotracheal tube. Changes of the endotracheal tube resistances were not affected by the site of cross‐sectional area reductions along the axes of the tubes. Conclusions: For endotracheal tubes of sizes 7.5, 8.0 and 8.5 mm, significant changes in the tubes resistances are observed when the partial obstructions of the tubes exceed certain critical values. The location of the partial obstruction did not affect the changes in the endotracheal tube resistances.

Apoptosis and the activity of ceramide, Bax and Bcl-2 in the lungs of neonatal rats exposed to limited and prolonged hyperoxia

BackgroundThe aim of the study is to examine the effect of limited and prolonged hyperoxia on neonatal rat lung. This is done by examining the morphologic changes of apoptosis, the expression of ceramide, an important mediator of apoptosis, the expression of inflammatory mediators represented by IL-1β and the expression of 2 proto-oncogenes that appear to modulate apoptosis (Bax and Bcl-2).MethodsNewborn rats were placed in chambers containing room air or oxygen above 90% for 7 days. The rats were sacrificed at 3, 7 or 14 days and their lungs removed. Sections were fixed, subjected to TUNEL, Hoechst, and E-Cadherin Staining. Sections were also incubated with anti-Bcl-2 and anti-Bax antisera. Bcl-2 and Bax were quantitated by immunohistochemistry. Lipids were extracted, and ceramide measured through a modified diacylglycerol kinase assay. RT-PCR was utilized to assess IL-1β expression.ResultsTUNEL staining showed significant apoptosis in the hyperoxia-exposed lungs at 3 days only. Co-staining of the apoptotic cells with Hoechst, and E-Cadherin indicated that apoptotic cells were mainly epithelial cells. The expression of Bax and ceramide was significantly higher in the hyperoxia-exposed lungs at 3 and 14 days of age, but not at 7 days. Bcl-2 was significantly elevated in the hyperoxia-exposed lungs at 3 and 14 days. IL-1β expression was significantly increased at 14 days.ConclusionExposure of neonatal rat lung to hyperoxia results in early apoptosis documented by TUNEL assay. The early rise in Bax and ceramide appears to overcome the anti-apoptotic activity of Bcl-2. Further exposure did not result in late apoptotic changes. This suggests that apoptotic response to hyperoxia is time sensitive. Prolonged hyperoxia results in acute lung injury and the shifting balance of ceramide, Bax and Bcl-2 may be related to the evolution of the inflammatory process.

Acute Exposure to Electronic and Combustible Cigarette Aerosols: Effects in an Animal Model and in Human Alveolar Cells

BACKGROUND Smoking electronic cigarettes (ECIG) is promoted as a safer alternative to smoking combustible cigarettes. This study investigates the effects of ECIG aerosol and cigarette smoke (CS) in an animal model and in human alveolar cell cultures (A549). METHODS Mice were divided into Control, ECIG, and CS. Animals were exposed for 6h/d to either lab air, ECIG or CS, for of 3 days. Total particulate matter exposure for the ECIG was set at higher levels compared to CS. Lung injury was determined by: (1) measurement of wet-to-dry ratio; (2) albumin concentration in the bronchoalveolar lavage fluid; (3) transcriptional expression of inflammatory mediators IL-1β, IL-6, TNF-α; (4) oxidative stress; (5) assessment of cell death; and (6) lung histopathology. Human alveolar cell cultures were treated with various concentrations of ECIG and CS aerosol extracts and the effects on cell proliferation were evaluated. RESULTS Wet-to-dry ratio was higher in CS when compared to ECIG. Albumin leak in bronchoalveolar lavage fluid was evident in CS but not in ECIG. ECIG exposure was only associated with a significant increase in IL-1β. In contrast, CS exposure resulted in significant increases in IL-1β, IL-6, TNF-α expression, and oxidative stress. TUNEL staining demonstrated significant cell death in CS but not in ECIG. At the cellular level, ECIG and CS extracts reduced cell proliferation, however, CS exhibited effects at lower concentrations. CONCLUSION Despite higher exposure conditions, ECIG exhibited less toxic effects on lungs of experimental animals and on A549 cell cultures when compared to CS.

Persistent snoring under conscious sedation during colonoscopy is a predictor of obstructive sleep apnea

BACKGROUND Obstructive sleep apnea (OSA) is characterized by cessation of breathing during sleep. Conscious sedation (CS) induces sleep and may uncover sleep-related breathing disorders. OBJECTIVE To determine whether snoring during CS is a sensitive predictor of OSA. DESIGN Matched cohort study. SETTING University-based ambulatory endoscopy center. PATIENTS Consecutive patients undergoing colonoscopy completed a detailed sleep questionnaire and physical examination geared toward detecting OSA (body mass index [BMI], neck circumference, and the presence of craniofacial abnormalities). The endoscopist was blinded to the information. INTERVENTIONS Portable nocturnal polysomnography. MAIN OUTCOME MEASUREMENTS Patients who snored during CS in the left lateral decubitus position for 10 seconds or longer were referred for polysomnography. Sex- and BMI-matched patients who did not snore served as control subjects. RESULTS A total of 131 patients were enrolled, and 24 (18.3%) of them snored. These patients (22 men, 2 women) had a predominance of Mallampati grade III/IV, higher Stanford and Epworth scale scores, and greater BMI and neck circumference and were more likely to report daytime sleepiness, decreased vigilance, and personality and mood changes (all P values <.05). All investigated patients who snored during CS had evidence of OSA versus 4 of 18 control subjects (mean apnea-hypopnea index: 40 events vs 5 events; P < .0001) (100% positive predictive value; 77.8% negative predictive value). Moderate or severe OSA was detected in 14 of 20 patients versus 1 of 18 control subjects (P < .001; 70% positive predictive value; 94.4% negative predictive value, 93% sensitivity, 74% specificity). Data obtained from sleep questionnaires and physical examination failed to accurately predict OSA. LIMITATIONS Single-center nature and relatively small number of patients developing the outcome variable. CONCLUSIONS Snoring during CS is a strong predictor of OSA. Given the medical and financial burden of undiagnosed OSA, these patients should be carefully identified and referred for sleep medication evaluation.

Sustained improvement in cognitive and emotional status of apneic patients after prolonged treatment with positive airway pressure.

Background: Obstructive sleep apnea-hypopnea syndrome (OSAH) is associated with impairment of cognitive functions and disturbances in emotional status. The aim of this study was to objectively evaluate the benefits of prolonged and sustained treatment for OSAH at two sleep centers serving rural community hospitals. Methods: Fifty-six patients diagnosed with OSAH syndrome underwent Cognistat, Beck Depression Inventory (BDI) and Millon Behavioral Medicine Diagnostic Inventory (MBMD) testing before initiation of treatment. Repeated testing after six months of therapy with positive airway pressure (PAP) was performed. Results: Significant improvements were noted in the BDI scale scores and a reduction in the MBMD scores reflected initial abnormal clinical personal symptoms that improved with treatment. MBMD analysis showed subjects with fewer symptoms of anxiety post baseline, which were sustained at 6 months post-treatment. Memory function improved as reflected by performance on the Cognistat. Women were observed to have a higher post-treatment BDI and younger patients appeared to have more shifts for improvement than older subjects in depressive symptomatology. Conclusions: These results indicate that prolonged and sustained PAP therapy is effective in restoring some of the deficiencies in patients with OSAH, particularly in terms of memory, depression, anxiety and increased psychological pathology.

Cigarette Smoking-Induced Cardiac Hypertrophy, Vascular Inflammation and Injury Are Attenuated by Antioxidant Supplementation in an Animal Model

Background: Cardiovascular diseases are the leading causes of morbidity and mortality worldwide. Cigarette smoking remains a global health epidemic with associated detrimental effects on the cardiovascular system. In this work, we investigated the effects of cigarette smoke exposure on cardiovascular system in an animal model. The study then evaluated the effects of antioxidants (AO), represented by pomegranate juice, on cigarette smoke induced cardiovascular injury. This study aims at evaluating the effect of pomegranate juice supplementation on the cardiovascular system of an experimental rat model of smoke exposure. Methods: Adult rats were divided into four different groups: Control, Cigarette smoking (CS), AO, and CS + AO. Cigarette smoke exposure was for 4 weeks (5 days of exposure/week) and AO group received pomegranate juice while other groups received placebo. Assessment of cardiovascular injury was documented by assessing different parameters of cardiovascular injury mediators including: (1) cardiac hypertrophy, (2) oxidative stress, (3) expression of inflammatory markers, (4) expression of Bradykinin receptor 1 (Bdkrb1), Bradykinin receptor 2 (Bdkrb2), and (5) altered expression of fibrotic/atherogenic markers [(Fibronectin (Fn1) and leptin receptor (ObR))]. Results: Data from this work demonstrated that cigarette smoke exposure induced cardiac hypertrophy, which was reduced upon administration of pomegranate in CS + AO group. Cigarette smoke exposure was associated with elevation in oxidative stress, significant increase in the expression of IL-1β, TNFα, Fn1, and ObR in rats aorta. In addition, an increase in aortic calcification was observed after 1 month of cigarette smoke exposure. Furthermore, cigarette smoke induced a significant up regulation in Bdkrb1 expression level. Finally, pomegranate supplementation exhibited cardiovascular protection assessed by the above findings and partly contributed to ameliorating cardiac hypertrophy in cigarette smoke exposed animals. Conclusion: Findings from this work showed that cigarette smoking exposure is associated with significant cardiovascular pathology such as cardiac hypertrophy, inflammation, pro-fibrotic, and atherogenic markers and aortic calcification in an animal model as assessed 1 month post exposure. Antioxidant supplementation prevented cardiac hypertrophy and attenuated indicators of atherosclerosis markers associated with cigarette smoke exposure.

Antioxidant activity of pomegranate juice reduces emphysematous changes and injury secondary to cigarette smoke in an animal model and human alveolar cells

Background Cigarette smoke (CS) increases oxidative stress (OS) in the lungs. Pomegranate juice (PJ) possesses potent antioxidant activities, attributed to its polyphenols. This study investigates the effects of PJ on the damaging effects of CS in an animal model and on cultured human alveolar cells (A549). Methods Male C57BL/6J mice were divided into the following groups: Control, CS, CS + PJ, and PJ. Acute CS exposure was for 3 days, while chronic exposure was for 1 and 3 months (5 days of exposure/week). PJ groups received daily 80 μmol/kg via bottle, while other groups received distilled water. At the end of the experiments, different parameters were studied: 1) expression levels of inflammatory markers, 2) apoptosis, 3) OS, and 4) histopathological changes. In vitro, A549 cells were pretreated for 48 hours with either PJ (0.5 μM) or vehicle. Cells were then exposed to increasing concentrations of CS extracted from collected filters. Cell viability was assessed by counting of live and dead cells with trypan blue staining. Results Acutely, a significant increase in interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α expression, apoptosis, and OS was noted in CS when compared to Control. PJ significantly attenuated the expression of inflammatory mediators, apoptosis, and OS. Chronically (at 1 and 3 months), increased expression of TNF-α was observed, and lung sections demonstrated emphysematous changes when compared to Control. PJ supplementation to CS animals attenuated the increased expression of TNF-α and normalized lung cytoarchitecture. At the cellular level, CS extract reduced cellular proliferation and triggered cellular death. Pretreatment with PJ attenuated the damaging effects of CS extract on cultured human alveolar cells. Conclusion The expression of inflammatory mediators associated with CS exposure and the emphysematous changes noted with chronic CS exposure were reduced with PJ supplementation. In vitro, PJ attenuated the damaging effects of CS extract on cultured human alveolar cells.

Activated protein C attenuates acute lung injury and apoptosis in a hyperoxic animal model.

Evidence suggests that activated protein C (APC) attenuates acute lung injury (ALI) through antithrombotic and anti-inflammatory mechanisms. The aim of this study was to determine the effects of APC on ALI in adult rats exposed to hyperoxic environment. Rats were divided into control, hyperoxia, hyperoxia + APC, and APC. Hyperoxia and hyperoxia + APC were exposed to 1, 3, and 5 days of hyperoxia. Hyperoxia + APC and APC were injected with APC (5 mg/kg, i.p.) every 12 h. Control and hyperoxia received isotonic sodium chloride solution injection. Measurement of wet to dry ratio and albumin leak demonstrated significant improvement in hyperoxia + APC when compared with hyperoxia. Apoptosis, as measured by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay, was significantly reduced in hyperoxia + APC when compared with hyperoxia. Histological evaluation of lung sections showed significant reduction in inflammation, edema, and in the number of marginating neutrophils in hyperoxia + APC as compared with hyperoxia. Transcriptional expression of lung inflammatory mediators demonstrated a time-dependent surge in the levels TNF-&agr;, IL-1&bgr;, and IL-6 in response to hyperoxia that was attenuated with APC administration in the presence of hyperoxia. In this rat model, APC attenuates lung injury and the expression of inflammatory mediators in ALI secondary to hyperoxia.

Relationship between intensive care complications and costs and initial 24 h events of trauma patients with severe haemorrhage

Background: The correlation between the events occurring in the initial 24 h following traumatic injury and the outcome of patients presenting with hypovolaemic shock is not clear. Methods: 27 patients who presented to a regional trauma centre with severe hypovolaemic shock were prospectively monitored. Evidence of severe hypovolaemia and shock was noted on admission with a mean systolic blood pressure of 73.8 mm Hg and a mean lactate level of 6.6 mM/l. The patients received a mean of 21.7 litres intravenous fluids during the first 24 h to maintain a mean systolic blood pressure ⩾110 mm Hg and urine output of ⩾50 ml/h. Multiple metabolic and physiological parameters were obtained prospectively and on an almost hourly basis for the first 24 h after admission. Patients were followed throughout their stay in hospital to record outcome, complications, total hospital costs and length of stay. Results: Using regression and multivariate analysis, adult respiratory distress syndrome was correlated with hypothermia and persistent lactic acidosis (R2 = 0.65, p = 0.005). Coagulopathy was associated with hypothermia (R2 = 0.43, p = 0.04). Length of stay and cost of hospitalisation were highly related to intensive care unit days, hospital-acquired infections and ventilator days (R2 = 0.86, p = 0.03). Conclusion: The initial 24 h events of trauma patients with haemorrhagic shock may have a significant impact on hospital costs and on complications developing later during hospitalisation.