Airway Occlusion Pressure Revisited.
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ABSTRACT:
SUBMITTER: Sassoon CS
PROVIDER: S-EPMC7193854 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:PURPOSE:To determine if a real-time magnetic resonance imaging (RT-MRI) method during continuous positive airway pressure (CPAP) can be used to measure neuromuscular reflex and/or passive collapsibility of the upper airway in individual obstructive sleep apnea (OSA) subjects. MATERIALS AND METHODS:We conducted experiments on four adolescents with OSA and three healthy controls, during natural sleep and during wakefulness. Data were acquired on a clinical 3T scanner using simultaneous multislice (SMS) RT-MRI during CPAP. CPAP pressure level was alternated between therapeutic and subtherapeutic levels. Segmented airway area changes in response to rapid CPAP pressure drop and restoration were used to estimate 1) upper airway loop gain (UALG), and 2) anatomical risk factors, including fluctuation of airway area (FAA). RESULTS:FAA significantly differed between OSA patients (2-4× larger) and healthy controls (Student's t-test, P < 0.05). UALG and FAA measurements indicate that neuromuscular reflex and passive collapsibility varied among the OSA patients, suggesting the presence of different OSA phenotypes. Measurements had high intrasubject reproducibility (intraclass correlation coefficient r > 0.7). CONCLUSION:SMS RT-MRI during CPAP can reproducibly identify physiological traits and anatomical risk factors that are valuable in the assessment of OSA. This technique can potentially locate the most collapsible airway sites. Both UALG and FAA possess large variation among OSA patients. LEVEL OF EVIDENCE:1 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2017;46:1400-1408.
| S-EPMC5568520 | biostudies-literature
Project description: Not available
| S-EPMC7498560 | biostudies-literature
Project description:ObjectivesThis study compared the efficacy and safety of minimal tourniquet pressure using either determined limb occlusion pressure (LOP) or estimated arterial occlusion pressure (AOP) for elective upper limb surgeries.MethodsForty patients undergone elective upper limb surgery under general hypotensive anesthesia were randomized into groups A and B, where tourniquet pressure was calculated using AOP estimation for group A and LOP determination for group B. AOP, LOP, the time needed to estimate the AOP and determine the LOP and set the tourniquet inflation pressure, tourniquet inflation pressure, initial and maximal systolic blood pressure, heart rate, intraoperative fentanyl requirement, arm circumference, and tourniquet time were recorded. Tourniquet performance was assessed, and signs of tourniquet-related complications were noticed.ResultsSystolic arterial blood pressure was comparable between the groups. Less time was recorded for measuring AOP or LOP and set the minimal inflation pressure (in second) in group A than in group B (62 ± 2 for group A vs. 120 ± 3 for group B; P < 0.001). The estimated AOP in group A was significantly higher than the determined LOP in group B (118 ± 2 vs. 91 ± 2; P < 0.001). Tourniquet inflation pressures were not significantly different between the groups. Tourniquet performance was excellent or good in all patients in both groups.ConclusionsArterial occlusion pressure estimation or LOP determination methods to set the tourniquet inflation pressure with hypotensive anesthesia can provide effective minimal inflation pressure and satisfactory surgical field for upper extremity surgeries without tourniquet-related complications.
| S-EPMC7353217 | biostudies-literature
Project description:Study objectivesAdherence to positive airway pressure (PAP) therapy for obstructive sleep apnea (OSA) remains a challenge in children. We hypothesized that the presence of another family member on PAP therapy (parent, sibling, other family member) would be associated with better adherence in the child.MethodsWe conducted a retrospective chart review to identify children < 18 years of age who had a new diagnosis of OSA between Jan 2011 and May 2013. Outcomes were objective PAP adherence at 1 week, 1 month, and 3 months. Potential predictors included family member on PAP therapy, patient demographics, and clinical characteristics. Group differences between children with and without a family member on PAP therapy were determined using χ(2) test and Wilcoxon two-sample test. PAP adherence measures at each time point and patterns of change across time between the two groups were examined using mixed-effects models.ResultsThe final analytic sample included 56 children: age 13.2 ± 3.7 years, 60% male, 67% African American, 65% obese, and 32% with developmental disabilities. The mean obstructive apnea-hypopnea index was 25.2 ± 28.7, and 19 (33%) had a family member on PAP therapy. Overall PAP adherence was 2.8 ± 2.4 h/night at 3 months. At month 3, the group with a family member on PAP therapy had significantly greater average nightly PAP use on all nights (3.6 ± 0.6 vs. 2.3 ± 0.39) and on nights used (4.8 ± 0.6 vs. 3.8 ± 0.40); (p value = 0.04).ConclusionsOverall PAP adherence was low, but having a family member on PAP therapy as a "role model" was associated with better adherence.CommentaryA commentary on this article appears in this issue on page 941.
| S-EPMC4918996 | biostudies-literature
Project description:Study objectivesReal-time monitoring of upper airway collapse during sleep could be instrumental for studies in biomechanics of obstructive sleep apnea (OSA) and selecting individualized treatment modalities. Although some imaging techniques are used under sedated sleep, none are available during the entire natural sleep process. We hypothesized that electrical impedance tomography (EIT) can be used for noninvasive continuous imaging of the upper airway during natural sleep and quantifying upper airway collapse in terms of its size.MethodsAfter determining surface landmarks to attach the electrodes for monitoring the retroglossal airway, EIT was conducted in 10 healthy participants. As a feasibility test of EIT in detecting upper airway collapse, transient airway closure was induced by the swallowing maneuver. These EIT images were confirmed by simultaneous magnetic resonance imaging (MRI) scans. Subsequently, EIT scans were conducted in 7 healthy participants and 10 patients with OSA under nonsedated sleep to determine whether it could identify upper airway narrowing or collapse. Respiratory events were identified by concurrent polysomnography (PSG).ResultsSwallowing-induced airway closure was identified successfully in all 10 participants on simultaneous EIT and MRI scans. Sizes and positions of the upper airway closures in reconstructed EIT images were well correlated with those in magnetic resonance images. Obstructive hypopnea and apnea were detected successfully by EIT in 10 patients with OSA, and no significant changes in EIT data were observed in 7 healthy participants during concurrent EIT and PSG tests. Additionally, conductivity changes in the airway were greater during obstructive apnea than during hypopnea (64.3% versus 26.3%, respectively; P < .001) compared with those during baseline respiration.ConclusionsEIT could be a useful real-time monitoring device for detecting upper airway narrowing or collapse during natural sleep in patients with OSA. Currently, changes in the upper airway size can be estimated with good accuracy, but shape estimation needs future improvements in the EIT image quality.
| S-EPMC6457513 | biostudies-literature
Project description:Study objectivesPositive airway pressure (PAP) treatment of obstructive sleep apnea reduces blood pressure (BP). Retrospective data suggest that African Americans (AA), a group at high-risk for hypertensive organ dysfunction, may have a greater BP response to PAP therapy than European Americans (EA). We examined the difference in 24-hour BP response to 3 months of PAP treatment between AA and EA.MethodsParticipants (n = 259, 161 AA and 98 EA) with apnea-hypopnea index ≥ 15 events/h from 2 prospective cohorts were included. t-Tests and multiple linear regression were used to examine BP outcomes in AA vs EA, adjusting for PAP adherence, socioeconomic status, and baseline characteristics.ResultsParticipants were middle aged (mean ± SD, 53.8 ± 9.3 years), 86% (227) men, apnea-hypopnea index 35.6 ± 19.2 events/h, and PAP adherence of 3.36 ± 2.24 h/day. The reductions in 24-hour systolic and diastolic BP (mm Hg) were not different in AA vs EA (systolic = -1.13 ± 12.1 vs -0.61 ± 12.8, P = .80 and diastolic = -0.74 ± 7.9 vs -0.80 ± 7.4, P = .96), and race was not a predictor of 24-hour systolic or diastolic BP reduction (P = .75 and 0.54). Socioeconomic status and PAP adherence demonstrated a significant interaction; low socioeconomic status was associated with an increase in 24-hour systolic BP (β = 19.3, P = .03) in the absence of PAP use but a greater reduction in 24-hour systolic BP with higher PAP adherence (β = -3.96, P = .03).ConclusionsTwenty-four hour BP response to PAP treatment is similar in AA and EA. Adherence to PAP treatment is more effective in improving 24-hour systolic BP in those with low SES.Clinical trial registrationRegistry: ClinicalTrials.gov; Name: Race and CPAP Effectiveness (RACE); URL: https://clinicaltrials.gov/ct2/show/NCT01960465; Identifier: NCT01960465 and Registry: ClinicalTrials.gov; Name: The Effects of Treating Obese and Lean Patients with Sleep Apnea (PISA); URL: https://clinicaltrials.gov/ct2/show/NCT01578031; Identifier: NCT01578031.CitationImayama I, Gupta A, Yen PS, et al. Socioeconomic status impacts blood pressure response to positive airway pressure treatment. J Clin Sleep Med. 2022;18(5):1287-1295.
| S-EPMC9059597 | biostudies-literature
Project description: Not available
| S-EPMC6444660 | biostudies-literature
Project description:BackgroundImproper mechanical ventilation can exacerbate acute lung damage, causing a secondary ventilator-induced lung injury (VILI). We hypothesized that VILI can be reduced by modifying specific components of the ventilation waveform (mechanical breath), and we studied the impact of airway pressure release ventilation (APRV) and controlled mandatory ventilation (CMV) on the lung micro-anatomy (alveoli and conducting airways). The distribution of gas during inspiration and expiration and the strain generated during mechanical ventilation in the micro-anatomy (micro-strain) were calculated.Study designRats were anesthetized, surgically prepared, and randomized into 1 uninjured control group (n = 2) and 4 groups with lung injury: APRV 75% (n = 2), time at expiration (TLow) set to terminate appropriately at 75% of peak expiratory flow rate (PEFR); APRV 10% (n = 2), TLow set to terminate inappropriately at 10% of PEFR; CMV with PEEP 5 cm H2O (PEEP 5; n = 2); or PEEP 16 cm H2O (PEEP 16; n = 2). Lung injury was induced in the experimental groups by Tween lavage and ventilated with their respective settings. Lungs were fixed at peak inspiration and end expiration for standard histology. Conducting airway and alveolar air space areas were quantified and conducting airway micro-strain was calculated.ResultsAll lung injury groups redistributed inspired gas away from alveoli into the conducting airways. The APRV 75% minimized gas redistribution and micro-strain in the conducting airways and provided the alveolar air space occupancy most similar to control at both inspiration and expiration.ConclusionsIn an injured lung, APRV 75% maintained micro-anatomic gas distribution similar to that of the normal lung. The lung protection demonstrated in previous studies using APRV 75% may be due to a more homogeneous distribution of gas at the micro-anatomic level as well as a reduction in conducting airway micro-strain.
| S-EPMC4350231 | biostudies-literature
Project description:Heart failure (HF) is a life-threatening disease and is a growing public health concern. Despite recent advances in pharmacological management for HF, the morbidity and mortality from HF remain high. Therefore, non-pharmacological approaches for HF are being developed. However, most non-pharmacological approaches are invasive, have limited indication and are considered only for advanced HF. Accordingly, the development of less invasive, non-pharmacological approaches that improve outcomes for patients with HF is important. One such approach may include positive airway pressure (PAP) therapy. In this review, the role of PAP therapy applied through mask interfaces in the wide spectrum of HF care is discussed.
| S-EPMC4244615 | biostudies-other
Project description: Not available
| S-EPMC8130584 | biostudies-literature