Respiratory care最新文献

Background: Surgical and N95 masks are commonly used in the prevention of respiratory virus transmission. The safety of wearing masks is well documented in healthy individuals but is unclear in people with chronic hypercapnia. In addition, masks are often poorly tolerated in this population. The present study assessed the effect of surgical and N95 masks in people with stable chronic hypercapnia using noninvasive ventilation (NIV).

Methods: A randomized crossover trial was performed. $S_{{\mathrm{pO}}_2}$ and transcutaneous CO₂ ($P_{{\mathrm{tcCO}}_2}$) were measured in participants wearing a surgical mask, an N95 mask, and no mask for a 20-min period at rest. Secondary outcomes included heart rate, breathing frequency, the A1 scale from the Multidimensional Dyspnea Profile (MDP), and the modified Borg dyspnea scale (mBORG).

Results: 24 participants (50% female; mean [SD] age 61 [13] years) were randomized and completed data collection. Over the 20-min study period, when compared with no mask, the mean differences for $S_{{\mathrm{pO}}_2}$ in surgical and N95 masks were 0.0% [95% CI: -1.0-0.9] and 0.3% [95% CI: -0.6-1.3]. For $P_{{\mathrm{tcCO}}_2}$ surgical mask, the mean difference was 0.0 mm Hg [95% CI: -1.3-1.3], and for N95 mask, the mean difference was 1.0 mm Hg [95% CI: 0.3-2.3]. There was no effect on heart rate or breathing frequency. Masks increased the mBORG (surgical mask median difference 0.75 points [95% CI: 0.25-2.00]; N95 mask median difference 1.50 [95% CI: 0.75-2.25]) and MDP (surgical mask median difference 1.5 points [95% CI: 0.5-2.5]; N95 mask median difference 2.5 points [95% CI: 1.0-3.0]) compared with no mask. Three participants requested to remove one or both masks early.

Conclusions: Wearing a surgical mask and N95 mask did not significantly affect gas exchange in subjects with chronic hypercapnia using NIV. However, dyspnea and breathing discomfort did increase.

Background: The factors that determine variability in impulse oscillometry (IOS) are not well defined.

Methods: We used IOS data from a well-screened population of active-duty service members (ADSMs) cleared for deployment (STAMPEDE II cohort) to identify variables independently associated with IOS measurements. We constructed our own predictive models and compared them with existing reference equations when applied to postdeployment STAMPEDE II subjects and two additional ADSM IOS datasets.

Results: There were 775 STAMPEDE II subjects without a history of respiratory symptoms, tobacco exposure, or lung disease (32.0 ± 9.0 years old, BMI = 26.8 ± 3.5, 16.4% female, 57.3% white) predeployment. Age, height, weight, sex, self-reported race/ethnicity, and military rank (a surrogate for socioeconomic status) in various combinations were significantly associated with the individual measures (R₅, R₂₀, X₅, fres, and AX) comprising impedance. Existing equations universally predicted lower impedance when applied to the 775 subjects from STAMPEDE II. External validation with postdeployment STAMPEDE II subjects and non-STAMPEDE II ADSM datasets showed our derived equations over-estimated while existing equations under-estimated IOS measurements. The degree of respective over and under-estimation was similar in magnitude but varied across IOS variables and between external datasets.

Conclusions: In a well-screened ADSM population, we found OS measurements were higher than predicted by existing equations. Our models suggest differences in predicted values were driven, at least in part, by the demographic characteristics (race and military rank) of the underlying derivation populations.

Background: Prone positioning is a recommended therapy for patients with moderate-to-severe ARDS; however, the optimal duration of this maneuver is still unknown.

Methods: We performed a systematic review and meta-analysis comparing clinical outcomes of extended (≥24 h) versus traditional prone positioning (16-24 h) of adults with moderate-to-severe ARDS receiving invasive mechanical ventilation.

Results: Ten studies involving 2,412 subjects met the inclusion criteria, including one randomized controlled trial and 9 observational studies, all with COVID-19-related ARDS. Extended prone positioning was associated with reduced mortality compared with the traditional approach (risk ratio [RR]: 0.76, 95% CI 0.66-0.86, I² = 12.8%). Sensitivity and subgroup analyses confirmed consistency across risk of bias, baseline P_aO2/F_iO2, and PEEP levels. No differences were found in duration of mechanical ventilation (mean difference [MD]: 2.43 days, 95% CI -1.06 to 5.92, I² = 70%) or ICU stay (MD: 1.31 days, 95% CI -1.07 to 3.68, I² = 55%). The extended strategy was associated with a higher incidence of pressure injuries (RR: 1.30, 95% CI 1.02-1.65, I² = 56%) but no differences in device displacement or hemodynamic instability. Certainty of evidence was rated as low to very low.

Conclusions: Extended prone positioning was associated with reduced mortality in ARDS but increased risk of pressure injuries, without impact on ventilator duration or ICU stay. While this strategy appears feasible and potentially beneficial, further randomized trials are warranted to confirm its role in routine practice.

Trial registration: PROSPERO no. CRD42024529311.

Background: High-flow nasal cannula (HFNC) reduces dead-space ventilation, but this effect is diminished by open-mouth breathing and partial airway obstruction. Consequently, it is uncertain whether HFNC provides respiratory support during endobronchial ultrasound (EBUS) procedures.

Methods: A single-center randomized controlled crossover study was conducted at the Rijnstate Hospital, Arnhem, the Netherlands, from November 2022 to August 2024.Patients with severe COPD (Gold III/IV) were evaluated to determine if HFNC reduces dead space ventilation during an EBUS procedure. Exclusion criteria were known neurodegenerative conditions, allergies to propofol or esketamine, pregnancy, upper-airway obstructions, or severe pulmonary hypertension.Subjects received two sequences of HFNC flow (30 and 70 L/min or vice versa) during EBUS.The primary outcome was CO₂ washout, determined by a 60-s capnography trace with and without HFNC flow to measure the difference in inspiratory, end-tidal CO₂, and β-angle.

Results: Twenty subjects with severe COPD (Gold III/IV) were included (Group A n = 10; Group B n = 10), of which one could not complete the bronchial measurements because of an obstructing carcinoma. CO₂ washout at carina was observed at 70 L/min of HFNC flow, demonstrated by a reduced inspiratory CO₂ of mean 6.0 mm Hg (95% CI: 4.5-8.3, P < .001) and end-tidal CO₂ of 5.3 mm Hg (95% CI: 2.3-7.5, P = .002), but not at 30 L/min of HFNC flow (mean inspiratory CO₂ difference of 1.5 mm Hg (95% CI: -2.3 to 6.0, P = .69) and mean end-tidal CO₂ difference of 0.8 mm Hg (95% CI: -2.3 to 3.0, P = .35). A flow of 70 L/min reduced inspiratory CO₂ in the left main bronchus (mean = 5.3 mm Hg; 95% CI: 2.3-8.3, P < .001), but not the end-tidal CO₂ (mean = 3.0 mm Hg; 95% CI: 0.0-6.0, P = .07).

Conclusions: An HFNC flow of 70 L/min reduced dead-space ventilation in subjects with severe COPD undergoing EBUS procedures during deep sedation, suggesting respiratory support during this procedure.

Pulse oximeters have been essential clinical tools for decades, helping to guide critical clinical decisions across a variety of settings. Despite their seemingly ubiquitous and central role, many clinicians may be unaware of limitations of the technology or ways to improve utility in the clinical settings. In some regions of the world, access to quality oximeters (and oxygen) remains a major challenge. In other regions, issues such as disparate performance and health disparities related to skin color have recently renewed decades old concerns. With upcoming changes to pulse oximeter regulatory frameworks as well as unprecedented amounts of published data on pulse oximeter performance, clinicians and researchers should familiarize themselves with the strengths and limitations of oximetry to ensure optimal implementation to improve safety and outcomes.

Background: A number of circuit configurations can be proposed for implementing mechanical ventilation, most of which are likely to impact the instrumental dead space and thus, on alveolar ventilation. This bench study was designed to investigate the effects of circuit configuration on $P_{{\mathrm{CO}}_2}$ with constant ventilator settings (iso-V_T condition; V_T: tidal volume) and to evaluate the modifications of V_T required to maintain stable alveolar ventilation with each circuit configuration (iso-$P_{\mathrm{ET}{\mathrm{CO}}_2}$ condition; end-tidal CO₂ partial pressure being considered as a surrogate for alveolar ventilation).

Methods: A total of 17 configurations were evaluated, including valve and leak circuits, heater humidifier or different heat and moisture exchangers, with or without catheter mount, and both invasive and noninvasive situations. All these evaluations were performed at 2 different respiratory rate, both in iso-V_T and iso-$P_{\mathrm{ET}{\mathrm{CO}}_2}$ conditions.

Results: With valve circuits, modifications of instrumental dead space resulted in $P_{\mathrm{ET}{\mathrm{CO}}_2}$ variations reaching up to 16 mm Hg from one configuration to another. The corresponding increase in the required V_T to compensate for the additional dead space reached up to 120 mL. Leak circuits significantly reduced the effects of instrumental dead space compared with valve circuits.

Conclusions: Any modification of the circuit configuration requires a systematic reevaluation of ventilation efficiency.

Mechanical ventilation is a complex yet essential aspect of critical care. This article provides a brief review of historical developments related to descriptions of ventilators, the derivation of the foundational equation of motion for the respiratory system and its derivatives, and a short overview of the taxonomy for modes of ventilation. These topics are then applied in a step-by-step procedure for interpreting patient-ventilator interactions through waveform analysis.

Background: Nasal nitric oxide (nasal NO) measurement is the most widely used screening tool for primary ciliary dyskinesia (PCD), but its accuracy may be affected by various factors. Based on our clinical experience, we hypothesized that nasal NO values vary across seasons, being lower in winter. This study investigates seasonal nasal NO variability in subjects referred for PCD screening.

Methods: This retrospective study (2010-2023) analyzed 434 subjects with clinical symptoms suggestive of PCD who underwent nasal NO testing at Schneider Children's Medical Center in Israel. Of these, 105 completed multiple measurements, yielding 578 nasal NO tests available for analysis. A separate cohort of 31 subjects diagnosed with PCD was analyzed independently. Seasons were defined based on the Mediterranean climate in Israel (according to Northern Hemisphere conventions).

Results: Among 434 subjects (median age 9 years, 58.5% male), median nasal NO was lower in winter (123 nL/min) than in summer (167 nL/min, P = .002), with a higher proportion of abnormal values (<66 nL/min) in winter (29.7% in January vs 6% in August, P = .007). Seasonal differences were similar across age groups (below and above 5 years of age). This seasonal pattern persisted throughout the observation period, though winter nasal NO variability decreased during COVID-19 pandemic lockdowns (2020-2022). In subjects with PCD, nasal NO remained consistently low (median 14 nL/min), with minimal seasonal variation.

Conclusion: Nasal NO levels exhibited seasonal variability, with statistically significant lower values during winter. Although most measurements remained within normal limits, there were many more abnormally low levels during winter, most of which normalized during summer. Therefore, repeat testing in another season, preferably summer, is recommended to ensure accurate PCD screening and avoid unnecessary invasive tests.

Wildfires have become increasingly frequent and severe, releasing large amounts of fine particulate matter (PM_2.5) and toxic gases that pose serious threats to respiratory health. This review summarizes current clinical evidence on the respiratory effects of wildfire smoke exposure, focusing on both short-term effects-such as respiratory symptoms, infections, and increased emergency department visits-and long-term consequences, including declines in pulmonary function and elevated mortality. The review highlights vulnerable populations-including pregnant individuals, infants, children, older adults, individuals with asthma or COPD, and firefighters, who experience disproportionate risks. It also compares the toxicity of wildfire-derived PM_2.5 to other pollution sources and identifies differences in clinical impact. Evidence-based protective strategies are discussed, including respiratory protection, behavioral interventions, and health care provider preparedness. Finally, the review identifies gaps in the current literature and emphasizes the need for longitudinal studies to evaluate chronic outcomes and improve public health responses to future wildfire events.