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Deep inspirations attenuate postprandial airway inflammation in college-aged adults with elevated baseline exhaled nitric oxide: A pilot study.
Kurti, SP, Smith, JR, Rosenkranz, SK, Emerson, SR, Edwards, ES, Jurrens, K, Laughlin, A, Harms, CA
Experimental lung research. 2020;(1-2):32-43
Abstract
Airway inflammation (assessed by exhaled nitric oxide (eNO)) increases after a single high-fat meal (HFM), yet this response may be modified by airway stretch and baseline eNO level.Purpose: The purpose of this study was to investigate whether deep inspirations (DIs) would attenuate airway inflammation post-HFM and whether this is modulated by baseline eNO level.Methods: A total of sixteen healthy college-aged participants completed a randomized cross-over study with 8 lower eNO (14.8 ± 2.0 ppb: 3 M/5F; age: 22.0 ± 2.2 yrs) and 8 higher eNO (29.3 ± 11.6 ppb 5 M/3F; age: 22.5 ± 2.6 yrs) participants. All participants completed a control (CON) condition (no DIs pre-HFM) and DI condition (60 DI's to total lung capacity immediately pre-HFM) after an overnight fast. The primary outcome was eNO. Participants had 20 minutes to consume the HFM (1 g fat/1 kg body weight) and eNO was performed at 2- and 4- hours post-HFM. To determine whether baseline eNO levels impacted the effect of DI's, a median split was performed on their baseline eNO level.Results: There was a significant increase in eNO as a main effect of time (p < 0.001). However when analyzing the potential effect of baseline eNO, there was no significant increase in eNO post-HFM in the higher eNO group in the DI condition (p = 0.54). DIs modified the eNO response to a HFM in the group with a higher baseline eNO value.Conclusions: These data display a possible bronchoprotective protect of DIs against postprandial airway inflammation in participants with higher initial eNO level.
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2.
The effect of biphasic inhalation profiles on the deposition and clearance of coarse (6.5 microm) bolus aerosols.
Clark, AR, Chambers, CB, Muir, D, Newhouse, MT, Paboojian, S, Schuler, C
Journal of aerosol medicine : the official journal of the International Society for Aerosols in Medicine. 2007;(1):75-82
Abstract
The influence of particle size upon deposition in the human airways is well understood. Pharmaceutical aerosol formulators strive to generate fine aerosols with the potential to penetrate into the deep lung. However, flow rate can also have a major influence on deposition, particularly with coarse aerosols. This study investigated the use of biphasic flow profiles with low flow in the proximal conducting airway as a means of effecting efficient delivery of a coarse aerosol. The study shows that 6.5-microm MMAD aerosol droplets can be deposited in the lung with high efficiency. The delivery technique achieved greater than 70% of the inhaled dose deposited in the whole lung and greater than 50% deposited in the lung periphery. Furthermore, the biphasic flow profiles used, with initial low flow segments of between 300 mL and 900 mL inhaled volume at 8 L/min, are practical flow regimens that should be acceptable to patients and that can be applied to single-breath dry powder inhalers. Twenty-four-hour clearance and Penetration Index measurements were used as a marker for peripheral deposition, and the data show a clear correlation between Penetration Index and 24-h retention.
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3.
Effect of FIO2 on oxidative stress during interval training at moderate altitude.
Wilber, RL, Holm, PL, Morris, DM, Dallam, GM, Subudhi, AW, Murray, DM, Callan, SD
Medicine and science in sports and exercise. 2004;(11):1888-94
Abstract
PURPOSE To evaluate the effect of different fractions of inspired oxygen (FIO2) on oxidative stress during a high-intensity interval workout in trained endurance athletes residing at altitude. METHODS Subjects (N = 19) were trained male cyclists who were residents of moderate altitude (1800-1900 m). Testing was conducted at 1860 m (PB 610-612 torr, PIO2 approximately 128 torr). Subjects performed three randomized, single-blind trials consisting of a standardized interval workout (6 x 100 kJ) while inspiring a medical-grade gas with FIO2 0.21 (PIO2 approximately 128 torr), FIO2 0.26 (PIO2 approximately 159 torr), and FIO2 0.60 (PIO2 approximately 366 torr). Serum lipid hydroperoxides (LOOH) and whole-blood reduced glutathione (GSH) were measured 60 min preexercise and immediately postexercise, and analyzed using standard colorimetric assays. Urinary malondialdehyde (MDA) and 8-hydroxydeoxyguanosine (8-OHdG) were measured 24 h preexercise and 24 h postexercise, and analyzed via HPLC and ELISA, respectively. RESULTS Compared with the control trial (FIO2 0.21), total time (min:s) for the 100-kJ work interval was faster (5% in FIO2 0.26; 8% in FIO2 0.60 (P < 0.05)) and power output (W) was higher (5% in FIO2 0.26, 8% in FIO2 0.60 (P < 0.05)) in the supplemental oxygen trials. There was a significant pre- versus postexercise main effect (P < 0.05) for LOOH and GSH; however, there were no significant differences in LOOH or GSH between the FIO2 trials. MDA and 8-OHdG were unaffected by either the interval training session or FIO2. CONCLUSION Supplemental oxygen used in conjunction with high-intensity interval training at altitude ("live high + train low via supplemental O2" (LH + TLO2)) results in a significant improvement in exercise performance without inducing additional free radical oxidative stress as reflected in hematological and urinary biomarkers.
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4.
A pilot study of quantitative aspiration in patients with symptoms of obstructive sleep apnea: comparison to a historic control group.
Beal, M, Chesson, A, Garcia, T, Caldito, G, Stucker, F, Nathan, CO
The Laryngoscope. 2004;(6):965-8
Abstract
OBJECTIVE It has been shown that many healthy people aspirate secretions at night. Patients with obstructive sleep apnea (OSA) have frequent episodes of gasping at night that may predispose them to aspiration. The purpose of this study was to determine whether patients with symptoms of OSA are predisposed to pharyngeal aspiration. STUDY DESIGN A prospective study in which patients with symptoms of OSA were compared with a historic group of normal controls by using the same methodology. METHODS The study was offered to patients with symptoms of OSA undergoing a sleep study. The radiotracer Technicium was infused through a plastic tube placed in the nasopharynx after the patient achieved stage II sleep. A chest radionuclide scan determined the amount of material aspirated. The Wilcoxon-rank sum test was used to compare the mean amount aspirated between the experimental and historic control groups. RESULTS Fourteen patients successfully completed the study. One normal volunteer in our study aspirated a quantity similar to the historic normal control group. The amount of aspirated material in the study group ranged from 0.152 to 3.648 mL, with a mean of 1.24 mL +/- 0.905 (SD). When compared with the historic normal control group, the patients with symptoms of OSA aspirated significantly more radio-tracer (P <.01). There was a lack of association between respiratory disturbance index and amount aspirated. CONCLUSIONS The results suggest there is an apparent risk of increased pharyngeal aspiration in patients with symptoms of OSA.
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5.
North American Summit on Aspiration in the Critically Ill Patient: consensus statement.
McClave, SA, DeMeo, MT, DeLegge, MH, DiSario, JA, Heyland, DK, Maloney, JP, Metheny, NA, Moore, FA, Scolapio, JS, Spain, DA, et al
JPEN. Journal of parenteral and enteral nutrition. 2002;(6 Suppl):S80-5
Abstract
Aspiration is the leading cause of pneumonia in the intensive care unit and the most serious complication of enteral tube feeding (ETF). Although aspiration is common, the clinical consequences are variable because of differences in nature of the aspirated material and individual host responses. A number of defense mechanisms normally present in the upper aerodigestive system that protect against aspiration become compromised by clinical events that occur frequently in the critical care setting, subjecting the patient to increased risk. The true incidence of aspiration has been difficult to determine in the past because of vague definitions, poor assessment monitors, and varying levels of clinical recognition. Standardization of terminology is an important step in helping to define the problem, design appropriate research studies, and develop strategies to reduce risk. Traditional clinical monitors of glucose oxidase strips and blue food coloring (BFC) should no longer be used. A modified approach to use of gastric residual volumes and identification of clinical factors that predispose to aspiration allow for risk stratification and an algorhythm approach to the management of the critically ill patient on ETF. Although the patient with confirmed aspiration should be monitored for clinical consequences and receive supportive pulmonary care, ETF may be continued when accompanied by appropriate steps to reduce risk of further aspiration. Management strategies for treating aspiration pneumonia are based on degree of diagnostic certainty, time of onset, and host factors.
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6.
Aspiration-related illnesses: definitions and diagnosis.
Zaloga, GP
JPEN. Journal of parenteral and enteral nutrition. 2002;(6 Suppl):S2-7; discussion S7-8
Abstract
BACKGROUND Aspiration is a leading cause of morbidity and mortality. It is the most common cause of pneumonia and one of the most serious adverse effects of enteral nutrition support. It is important to use standardized terminology to define and discuss aspiration-related illnesses. METHODS Review of the medical literature and extraction of definitions and descriptions of aspiration-related illnesses. RESULTS Definitions, clinical features, diagnosis, and treatment of common aspiration-related illnesses are discussed. CONCLUSIONS Precisely defined terminology of aspiration-related illnesses adds consistency to this area of medicine and simplifies analysis and comparison of clinical studies.
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7.
Detection of aspiration in enterally fed patients: a requiem for bedside monitors of aspiration.
Maloney, JP, Ryan, TA
JPEN. Journal of parenteral and enteral nutrition. 2002;(6 Suppl):S34-41; discussion S41-2
Abstract
BACKGROUND Pulmonary aspiration of gastric and oropharyngeal contents is common in enterally fed patients. Detection of early aspiration in these patients has relied on clinical impression, the coloring of enteral feedings with dyes, and less commonly the detection of elevated glucose in tracheal aspirates. The potential benefits, risks, and clinical use of bedside monitors of aspiration are under increasing scrutiny. METHODS Literature review. Although this review reflects the opinions of the authors, recommendations of an expert consensus panel (North American Summit on Aspiration, which included one author, J. P. Maloney) were also used to guide recommendations. The specific recommendations of that panel are presented elsewhere. RESULTS No large prospective clinical trials have been done to evaluate the use and safety of bedside monitors for aspiration. Clinical impression remains a poor "gold standard" of aspiration diagnosis in enterally fed patients. The coloring of enteral feedings with blue dyes (chiefly FD&C Blue No.1) is ubiquitous in hospitals despite evidence that it is not sensitive and potentially harmful. Cases of absorption of blue dye from enteral feedings in patients with critical illness have raised concern about the safety of the blue dye method, particularly in light of apparent toxic effects of these dyes on mitochondria. The glucose detection method has not been embraced; it too has little use and is labor intensive. CONCLUSIONS Use of colored dyes in enteral feedings and glucose detection methods should be abandoned. Nonrecumbent positioning is an evidenced-based method for aspiration prevention that needs to be re-emphasized. Novel bedside methods of detecting early aspiration are needed to supplement preventative strategies.
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8.
Risk factors for aspiration.
Metheny, NA
JPEN. Journal of parenteral and enteral nutrition. 2002;(6 Suppl):S26-31; discussion S32-3
Abstract
BACKGROUND There are numerous risk factors for aspiration in tube-fed critically ill patients. However, there is confusion about the extent to which these factors actually contribute to aspiration. The purpose of this literature review was to summarize findings from selected research studies. METHODS A nonexhaustive literature search was conducted to identify risk factors for aspiration in tube-fed, critically ill patients. The most commonly cited factors were decreased level of consciousness, supine position, presence of a nasogastric tube, tracheal intubation and mechanical ventilation, bolus or intermittent feeding delivery methods, high-risk disease and injury conditions, and advanced age. RESULTS Many studies of aspiration risk factors have relatively small sample sizes and used equivocal definitions of aspiration. Although some addressed aspiration as an outcome, others considered gastroesophageal reflux or pneumonia as outcomes. Despite these variations, authors almost uniformly agree that a decreased level of consciousness and a sustained supine position are major risk factors for aspiration. There is less agreement regarding the effect of a nasogastric tube (or its size) on aspiration and on the effect of various formula delivery methods. CONCLUSIONS A decreased level of consciousness is a major risk factor for aspiration, as is a sustained supine position. Although some authors favor using small-bore feeding tubes to prevent aspiration, there seems to be insufficient data to warrant this action. Although strong data are lacking regarding feeding delivery methods, there are more data to support continuous feedings than bolus/intermittent feedings in high-risk patients.
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9.
Equal aspiration rates in gastrically and transpylorically fed critically ill patients.
Esparza, J, Boivin, MA, Hartshorne, MF, Levy, H
Intensive care medicine. 2001;(4):660-4
Abstract
OBJECTIVES To determine the difference in aspiration rates between gastrically and transpylorically fed patients in the intensive care unit. DESIGN A prospective controlled study of critically ill patients randomized to receive either a gastrically placed feeding tube or a transpylorically placed feeding tube. SETTING University teaching hospital's medical intensive care unit. The study was conducted over 14 months. PATIENTS Fifty-four critically ill subjects (with an overall 40% mortality) with similar baseline age, severity of illness, and nutritional needs requiring enteral nutrition, with 51 completing the study. INTERVENTIONS All feeds were tagged with technetium-99m radiolabeled sulfur colloid, and the pulmonary secretions or lungs of each patient were scanned on a daily basis to determine whether aspiration had occurred. Patients were fed according to their assigned tube placement which was verified daily by continuous electromyography. MEASUREMENTS AND RESULTS Of 27 gastrically fed patients 2 (7%) had evidence of scanned feed in pulmonary secretions or the lung, compared to 3 of 24 (13%) transpylorically fed patients (n.s.). Clinical suspicion of aspiration was insensitive and detected only 60% of isotopically documented aspirations with a positive predictive value of 27%. CONCLUSION There was no difference in aspiration rates between gastrically and transpylorically fed critically ill patients.