Discussion on "Effects of High-Flow Nasal Cannula on the Work of Breathing in Patients Recovering From Acute Respiratory Failure".
Crit Care Med. 2018 Mar;46(3):e274-e275
Authors: Xu F, Fei D, Jiang L, Jiang P
PMID: 29474339 [PubMed - in process]
Distinction between rhinovirus-induced acute asthma and asthma-augmented influenza infection.
Clin Exp Allergy. 2018 Feb 23;:
Authors: Guibas GV, Tsolia M, Christodoulou I, Stripeli F, Sakkou Z, Papadopoulos NG
BACKGROUND: Rhinovirus (RV) is an established trigger of asthma attacks, whereas such a link is less consistent for influenza virus (IFV).
OBJECTIVE: In the context of precision medicine, we hypothesized that IFV infection may cause a condition essentially different from RV, and we investigated this by evaluating clinical characteristics of RV/IFV-positive and -negative children with respiratory symptoms and/or fever.
METHODS: 1207 children, 6-months to 13-years old, hospitalized for flu-like illness were recruited in this cross-sectional study. Collected information included demographics, medical history, symptoms/physical findings/diagnosis at presentation, and treatment. Nasal secretions were PCR-tested for IFV/RV. Associations were evaluated with adjusted logistic regression models.
RESULTS: RV positivity was associated with an asthma-like presentation, including increased wheeze/effort of breathing/diagnosis of acute asthma, and decreased fever/vomiting. Conversely, IFV+ children presented with less wheeze/effort of breathing/diagnosis of acute asthma, while they were more frequently febrile. In those with previous asthma history, both viruses induced wheeze, however, IFV was uniquely associated with a more generalised and severe presentation including fever, rales, intercostal muscle retractions and lymphadenopathy. These symptoms were not seen in RV+ asthmatics, who had fewer systemic signs and more cough.
CONCLUSIONS AND CLINICAL RELEVANCE: In children with respiratory symptoms and/or fever, RV but not IFV is associated with wheeze and an asthma-like presentation. In those with an asthma history, IFV causes more generalised and severe disease that may be better described as 'asthma-augmented influenza' rather than an 'asthma attack'. Differences in the acute conditions caused by these viruses should be considered in the design of epidemiological studies. This article is protected by copyright. All rights reserved.
PMID: 29473978 [PubMed - as supplied by publisher]
Methodological Implications and Repeatability of Nasal Nitric Oxide: Relevance for Challenge Studies.
Adv Exp Med Biol. 2018 Feb 22;:
Authors: Hoffmeyer F, Sucker K, Berresheim H, Monsé C, Jettkant B, Beine A, Raulf M, Brüning T, Bünger J
There is an interest in assessing changes in nasal NO (nNO) levels as an effect marker of upper airways. In this study, we examined methodologic influences on short and long term repeatability of nNO levels assessed by a portable electrochemical analyzer. Nine atopic and eighteen healthy subjects were exposed for 4 h to ethyl acrylate concentration of 0.05 ppm (sham) and mean concentrations of 5 ppm (either constant 5 ppm or variable 0 to 10 ppm). Sampling of nNO was performed by using passive aspiration during both breath-holding (634 ppb) or calm tidal breathing (364 ppb, p < 0.0001). The intra-session (between-session) repeatability in terms of coefficient of variation was 16.4% (18.5%) using the tidal-breathing and 8.6% (13.0%) using the breath-holding method, respectively. Atopic subjects demonstrated a significant increase in nNO (breath-holding mean 16%, tidal-breathing mean 32%) after applying a constant ethyl acrylate concentration (5 ppm). Our findings suggest that the less elaborate tidal-breathing method might be sufficient to detect significant changes at a group level. Given a lower coefficient of variation of breath-holding we assume there is an advantage of that approach at an individual level. Further research is needed to validate the usefulness of nNO in the evaluation of irritative, non-allergic responses.
PMID: 29468535 [PubMed - as supplied by publisher]
Arousal-Induced Hypocapnia Does Not Reduce Genioglossus Activity in Obstructive Sleep Apnea.
Sleep. 2017 Jun 01;40(6):
Authors: Cori JM, Thornton T, O'Donoghue FJ, Rochford PD, White DP, Trinder J, Jordan AS
Study Objectives: To determine whether arousals that terminate obstructive events in obstructive sleep apnea (OSA) (1) induce hypocapnia and (2) subsequently reduce genioglossus muscle activity following the return to sleep.
Methods: Thirty-one untreated patients with OSA slept instrumented with sleep staging electrodes, nasal mask and pneumotachograph, end-tidal CO2 monitoring, and intramuscular genioglossus electrodes. End-tidal CO2 was monitored, and respiratory arousals were assigned an end-arousal CO2 change value (PETCO2 on the last arousal breath minus each individual's wakefulness PETCO2). This change value, in conjunction with the normal sleep related increase in PETCO2, was used to determine whether arousals induced hypocapnia and whether the end-arousal CO2 change was associated with genioglossus muscle activity on the breaths following the return to sleep.
Results: Twenty-four participants provided 1137 usable arousals. Mean ± SD end-arousal CO2 change was -0.2 ± 2.4 mm Hg (below wakefulness) indicating hypocapnia typically developed during arousal. Following the return to sleep, genioglossus muscle activity did not fall below prearousal levels and was elevated for the first two breaths. End-arousal CO2 change and genioglossus muscle activity were negatively associated such that a 1 mm Hg decrease in end-arousal CO2 was associated with an ~2% increase in peak and tonic genioglossus muscle activity on the breaths following the return to sleep.
Conclusions: Arousal-induced hypocapnia did not result in reduced dilator muscle activity following return to sleep, and thus hypocapnia may not contribute to further obstructions via this mechanism. Elevated dilator muscle activity postarousal is likely driven by non-CO2-related stimuli.
PMID: 28419356 [PubMed - indexed for MEDLINE]