Respiratory care最新文献

Background: Several factors influence aerosol delivery during mechanical ventilation, such as patient characteristics, device configuration, and ventilator settings. This study aimed to evaluate how ventilator settings, humidification, nebulizer positions, bias flows, and circuit adapters affected aerosol delivery during invasive ventilation. Methods: Using an in vitro model, aerosol delivery of albuterol (2.5 mg/3 mL) via a vibrating mesh nebulizer was tested under 28 conditions during invasive ventilation. A systematic stepwise ruling-out approach was taken over 3 phases: (1) dry circuit, (2) dry circuit with exhaled humidity, and (3) heated and humidified circuit with exhaled humidity. Variables included ventilator settings (high vs low), nebulizer positions (proximal to the endotracheal tube vs distal), bias flows (2 vs 5 L/min), and circuit adapters (Y- vs V-shaped). The variables deemed unimportant were progressively excluded in later phases. Each condition was tested 5 times. Drug deposition was collected on filters, eluted, and quantified using ultraviolet spectrophotometry at 276 nm. Results: High ventilator settings significantly increased inhaled doses compared with lower settings across most conditions (all P < .05), with the greatest absolute increase of inhaled dose was observed in dry circuits without exhaled humidity (11-22%). This effect was reduced to 4-7% with the use of exhaled humidity in both dry and heated humidified circuits. Proximal nebulizer placement yielded higher doses than distal placement under high settings in dry circuits without exhaled humidity, but this difference was diminished or absent when exhaled humidity or heated humidification were introduced. Bias flow and adapter type had minimal impact on inhaled dose, except in specific conditions under dry circuit without exhaled humidity. Conclusions: In dry circuits without exhaled humidity, aerosol delivery was substantially affected by ventilator settings and nebulizer placement, whereas bias flow and circuit adapter types had no notable impact. However, the effects of ventilator settings and nebulizer placement diminished in circuits with exhaled humidity or heated humidification.

Background: Chronic respiratory symptoms are reported after military deployment in support of combat operations. The spectrum of clinical lung diseases was initially defined by the Study of Active Duty Military for Pumonary Disease Related to Environmental Deployment Exposures (STAMPEDE) III. Does cardiopulmonary exercise testing (CPET) performed during this evaluation demonstrate differences based on established clinical diagnoses? Methods: Military personnel with chronic respiratory symptoms underwent a standardized evaluation as reported in the STAMPEDE III study. CPET was performed on a treadmill using a Bruce protocol, and all participants exercised to maximal exertion. Standard cardiac and respiratory CPET parameters were compared based on diagnosis, pulmonary function testing, and underlying comorbidities. Historical control patients included asymptomatic, nondeployed military personnel with normal imaging and spirometry who previously performed identical CPET testing. Results: In total, 356 participants from STAMPEDE III (38.3 ± 8.7 years) completed a single CPET study during the standardized evaluation. Values were compared with 108 nondeployed controls (28.8 ± 3.9 years). Participants versus controls demonstrated a significant reduction in exercise capacity based on time (10:09 ± 1:51 vs 12:58 ± 2:11, P < .001), metabolic equivalents (10.9 ± 1.7 vs 12.8 ± 1.7, P < .001), and V̇_O2 peak (mL/kg/min) (37.3 ± 7.1 vs 46.7 ± 6.9, P < .001). In the comparison of respiratory parameters, both minute ventilation/maximum voluntary ventilation (0.80 ± 0.18 vs 0.69 ± 0.15) and breathing reserve percentage (20.3 ± 17.5 vs 25.9 ± 13.1) identified significant differences (P < .05) driven by asthma and lower airway categories, whereas breathing frequency and tidal volume/inspiratory capacity were not different. Differences in exercise capacity were influenced by the presence of post-traumatic stress disorder/traumatic brain injury, mental health disorders, and body mass index >30 kg/m². Conclusions: The use of CPET for postdeployment pulmonary diagnoses showed a decrease in exercise capacity compared with normal controls. Although several ventilatory parameters were elevated in asthma and lower airway diseases, individuals diagnosed with only exertional dyspnea did not demonstrate changes. Propensity matching confirmed that CPET does not suggest undiagnosed respiratory disease during a normal postdeployment pulmonary evaluation.

Background: The airway pressure release ventilation (APRV)-based time controlled adaptive ventilation (TCAV) protocol can potentially minimize ventilator-induced lung injury (VILI). Inspiratory pressure rise time (IPRT) is a parameter available in pressure-controlled ventilation modes, yet its role within TCAV remains unclear. We hypothesized that varying IPRTs impact lung emptying and associated ventilatory parameters (driving pressure [ΔP], intrinsic PEEP [PEEPi], exhaled tidal volume [V_Te]). Methods: This single-center, prospective exploratory study included 10 intubated subjects ventilated utilizing the TCAV protocol. Subjects underwent consecutive experimental trials with IPRTs of 500 and 1,000 ms, each preceded by a baseline (BL) with an IPRT of 0 ms. Analyzed parameters were ventilator-derived ΔP (ΔP_vent), PEEPi, and V_Te. Elastance (E_RS = ΔP_vent/V_Te) and elastance-derived ΔP (ΔP_elast = E_RS × V_Te) were calculated. End-expiratory lung volume (EELV) and end-inspiratory lung volume were assessed through electrical impedance tomography (EIT). Results: Prolonged IPRT increased ΔP_elast compared with ΔP_vent in each baseline/trial combination (ΔP_vent 13.5 ± 1.5 cm H₂O vs ΔP_elast 18.4 ± 2.7 cm H₂O at 1,000 ms IPRT, P < .001) through a loss of PEEPi. Conventional PEEPi measurements did not detect these changes. The EIT data showed a reduction in EELV during the trials. Conclusions: IPRT prolongation under TCAV reduced EELV/PEEPi, therefore increasing ΔP. Conventional PEEPi measurement methods are misleading in this context. We therefore suggest adding the recommendation to set IPRT to 0 ms for the TCAV protocol.

Background: Functional arterial hemoglobin oxygen saturation is a critical clinical parameter and the reference for verifying accuracy of S_pO2 values during performance testing of a pulse oximeter. Variable performance between blood gas analyzers that perform co-oximetry may complicate interpretation of research studies and regulatory guidance. This study quantifies systematic differences between multiple same model analyzers from two widely used brands of co-oximeters. Methods: Three sequential experiments were conducted using controlled hypoxemia in healthy adult volunteers according to regulatory clearance criteria for use of functional arterial oxygenation from co-oximetry analysis (sO₂), to simultaneous S_pO2 values over the range of 70-100%. To account for potential methodological confounders in experiments 1 and 2, a third experiment analyzed 31 arterial samples across multiple same model analyzers for co-oximetry (two Werfen GEM Premier 5000, and three Radiometer ABL90 Flex) in a randomized order after simultaneous preparation. Statistical analysis included paired differences, mixed-effects modeling, and variance analysis to isolate analyzer-specific effects while controlling for confounding variables. Results: The GEM analyzers consistently measured sO₂ 2.3% higher on average than ABL analyzers (95% CI 2.01-2.63%, P < .001). This difference was more pronounced at lower saturations (3.2% in the sO₂ 70s range vs 1.4% in the 90s range). Despite strong correlation between measurements (r = 0.999), 96.8% of paired samples differed by >1% and 61.3% by >2%. Within-manufacturer variability was similar between brands (mean absolute difference: ABL 0.38%, GEM 0.47%, P = .55). Conclusions: Clinically important systematic differences in sO₂ measurement exist between GEM and ABL blood analyzers that perform co-oximetry, with potential implications for patient care and pulse oximeter verification studies. Larger studies with more co-oximeter brands, coupled with blood tonometry, are needed to better characterize these findings. In the meantime, regulatory standards and reports of pulse oximeter clinical trials should account for these findings and specify which manufacturer's co-oximeters were used.

Background: Sleep-related breathing disorders (SRBDs) are associated with perioperative morbidity. Guidelines recommend preoperative screening for SRBDs, but testing is rarely completed before surgery. We aimed to address this gap by expediting preoperative home sleep apnea testing (HSAT) among persons with suspected SRBDs. Methods: We developed an expedited referral pathway for preoperative HSAT in a subset of persons with high-risk SRBDs (HR-SRBDs) (ie, obesity hypoventilation syndrome and overlap of COPD and obstructive sleep apnea). The primary outcome was change in rate of preoperative HSAT interpretation. Secondary outcomes were surgery delay or cancellation rates and correct use of the referral pathway by providers. Results: After implementation of the expedited HSAT referral pathway, the preoperative HSAT interpretation rate increased nearly 6-fold compared with preimplementation (7% vs 43%, P = .001). Time elapsed from sleep study referral to surgery, a surrogate for surgery delay, did not substantially change from pre- to postimplementation (7 d vs 10 d, P = .26). There were no surgery cancellations. Providers used the expedited HSAT referral pathway correctly 36% of the time in the first 3 months; this increased to 67% in the last 3 months of the postimplementation period. Conclusions: Preoperative HSAT interpretation in persons with HR-SRBDs was feasible without causing surgery delay or cancellations and may improve management of persons with SRBDs perioperatively. Future studies should clarify if preoperative identification of HR-SRBDs improves outcomes in this surgical population.

Background: Albumin is often used to augment diuresis in fluid overloaded patients. The purpose of this study was to determine the association between albumin administration and fluid balance and respiratory outcomes in mechanically ventilated children. Methods: This was a single-center retrospective cohort study of patients 1 month to <18 years old admitted to the pediatric or cardiac ICU between July 1, 2013, and July 1, 2019 who received 25% albumin while mechanically ventilated. The primary outcome was net fluid balance 48 hours before and after albumin administration. Secondary end points included diuretic requirement, oxygenation index (OI), ventilatory index (VI), and lung compliance. A multivariate regression analysis was completed to assess the odds of having negative fluid balance as a function of albumin administration. Results: There were 268 patients screened for study inclusion, of which 110 met inclusion criteria. The median net fluid balances prior to and after albumin were +38.9 mL/kg/48 h (IQR -6.6 to +118) and +6.5 mL/kg/48 h (-49.8 to +57.3), respectively (unadjusted P < .001). There was no difference in OI, VI, or lung compliance. The regression analysis demonstrated significantly higher odds of a negative fluid balance after albumin administration compared with before. Conclusions: Results from this study demonstrated a less positive fluid balance for the 48 h after albumin administration as compared with the 48 h before administration. Despite this reduction in fluid balance after albumin, there were no differences in several respiratory outcomes. Larger multi-center observational or randomized, controlled trials are required to determine if a decrease in positive fluid balance from albumin administration has an impact on respiratory outcomes.

Respiratory therapists (RTs) provide essential care across the United States of America (USA) in various health care settings, with a prominent role in critical care. RTs specialize in managing mechanical ventilation, maintaining patent airways, and assisting with specialized procedures. While RTs in the USA have a broad scope of practice, it varies based on multiple factors; as a result, limited evidence exists detailing their specific roles and responsibilities. This review aims to map the breadth and depth of the available literature on RT practice in critical care within the USA. This review included three aims: (1) describe the practices and roles of RTs in adult critical care settings (including value-efficiency scores), (2) summarize the different RT models of care in critical care teams in the USA, and (3) investigate regional variations in RT practices in critical care across the USA. This scoping review was guided by the Joanna Briggs Institute methodology for scoping reviews. Studies that described the RT role in adult critical care within the USA were included. Data extraction was informed by the Respiratory Therapy Practice-Based Outcome Initiative (RT-PBOI) model and value-efficiency metrics. Eighty peer-reviewed articles and 45 pieces of grey literature met the inclusion criteria (total 125). RTs' roles and responsibilities were categorized per the RT-PBOI model as follows: Technical Skills (131), Approach to Practice (90), Leveraging Capacity (45), Strategic Expertise (73), and Growing Value for the Future (16). The grey literature (45) provided brief descriptions of the RT scope from various state regulatory/licensing bodies or state respiratory societies, guidelines, reports, and/or position statements. While RTs are crucial to critical care, gaps remain in quantifying their impact and clearly defining their evolving scope of practice. Further research is essential to optimize their integration into care teams, quantify impact, and improve patient outcomes.