Airway Opening Research Articles

A Prospective Randomised Comparative Study of Baska Mask and I-Gel for Airway Management in Elective Surgeries: Focus on Airway Sealing Pressure, Insertion Time, and Haemodynamic Response

Introduction: General anesthetic procedure requires a safe and open airway. Endotracheal intubation is the gold standard for airway management; it is being replaced by supraglottic airway devices because they are easy to introduce, better tolerated and results in a lesser haemodynamic response. As both the Baska mask and I-gel have a non-inflatable self-sealing mechanism, these two devices were compared in our study in terms of time taken for insertion, airway sealing pressure, the number of attempts, hemodynamic changes, and complications. Methods: A Prospective comparative study was conducted on 90 patients (45 in each group), aged 18-60 years, undergoing elective surgeries under general anesthesia at Tertiary care Hospital, Madurai. Patients were randomized into two groups using the computer generated statistical software STATA version14 (Texas, USA): Group B: Airway was secured by insertion of Baska mask. Group I: Airway was secured by insertion of I Gel. Following assessments were done to evaluate the SAD: Time taken to insert the device, airway sealing pressure, rate of successful insertion, number of attempts, Haemodynamic parameters, laryngopharyngeal morbidity. Data were analyzed using Student t-tests and chi-square tests, with p < 0.05 considered significant. Results: The mean airway sealing pressure of the Baska mask (26.1+6.1 cmH2O) was significantly higher than that of the I-gel (23.1± 5.9 cmH2O) with a P value of 0.019 which was statistically significant. In our study the time taken to insert the device, for Baska mask it was 18.9+4.1 seconds and for the I gel it was 17.2±5.1 seconds with a P value of 0.089 which was statistically insignificant. In our study there was no statistical difference between Baska mask and I-gel groups in regards to hemodynamic changes (Heart rate and Mean arterial pressure). This may be due to the same stress response produced by the both devices. Conclusion: Baska mask is superior to I-gel in positive pressure ventilation under general anaesthesia for short surgical procedures with statistically significant higher airway sealing pressure though it has comparable time of insertion, haemodynamic changes and laryngopharyngeal morbidity.

Inter-lung asymmetrical airway closure cause insufflation delay between lungs in acute hypoxemic respiratory failure

BackgroundElectrical Impedance Tomography (EIT) can quantify ventilation in the two lungs and be used to measure the airway opening pressure (AOP) of each lung. Asymmetrical AOPs can cause inter-lung insufflation delay.ObjectivesTo assess the relation between AOP asymmetry and inter-lung insufflation delay at different PEEP levels.MethodsPatients with acute hypoxemic respiratory failure and airway closure were included. Low-flow pressure-volume curves and EIT signal were recorded during controlled ventilation and for some patients in pressure support ventilation.Results23 patients were studied, 22 patients had ARDS, 9 patients had asymmetrical airway closure with an AOP of 10 [6–13] cmH20 in the sicker lung (AOPsicker) vs. 5 [3–9, ] cmH20 in the healthier lung. During a low flow inflation, the inter-lung inflation delay was 0 [0-112]ms vs. 1450 [375–2400]ms in patients without or with asymmetrical AOPs, p < 0.0001. This delay was correlated to the difference of AOP between the 2 lungs, Spearman R2 = 0.800, p < 0.0001. During tidal ventilation, median delay was 0 [0–62] ms vs. 150 [50–355] ms in patients without vs. with asymmetry, p = 0.019. Setting PEEP at the crossing point of a decremental EIT-based PEEP trial decreased the inter-lung insufflation delay. During pressure support insufflation delay could still be measured and was reduced by increasing PEEP from 5 to 10 cmH2O in patient with asymmetrical lung injury.ConclusionIn asymmetrical airway closure, titrating PEEP can minimize inter-lung insufflation delay and can be monitored by EIT. Reducing the delay and reducing ventilation asymmetry is also feasible during pressure support ventilation when low flow inflation curves cannot be performed.

Design and Implementation of a Computer-Controlled Hybrid Oscillatory Ventilator.

During mechanical ventilation, lung function and gas exchange in structurally heterogeneous lungs may be improved when volume oscillations at the airway opening are applied at multiple frequencies simultaneously, a technique referred to as multifrequency oscillatory ventilation (MFOV). This is in contrast to conventional high-frequency oscillatory ventilation (HFOV), for which oscillatory volumes are applied at a single frequency. In the present study, as a means of fully realizing the potential of MFOV, we designed and tested a computer-controlled hybrid oscillatory ventilator capable of generating the flows, tidal volumes, and airway pressures required for MFOV, HFOV, conventional mechanical ventilation (CMV), as well as oscillometric measurements of respiratory impedance. The device employs an iterative spectral feedback controller to generate a wide range of oscillatory waveforms. The performance of the device meets that of commercial mechanical ventilators in volume-controlled mode. Oscillatory modes of ventilation also meet design specifications in a mechanical test lung, over frequencies from 4 to 20 Hz and mean airway pressure from 5 to 30 cmH2O. In proof-of-concept experiments, the oscillatory ventilator maintained adequate gas exchange in a porcine model of acute lung injury, using combinations of conventional and oscillatory ventilation modalities. In summary, our novel device is capable of generating a wide range of conventional and oscillatory ventilation waveforms with potential to enhance gas exchange, while simultaneously providing less injurious ventilation.

Benefits of Virtual Reality Training for Cardiopulmonary Resuscitation Skill Acquisition and Maintenance

Objectives To investigate the benefits of virtual reality (VR) first-aid training in acquiring cardiopulmonary resuscitation (CPR) skills. Methods A total of 100 non-medical professional volunteers from Nanchang were selected in March 2021 using the convenience sampling method. They were randomly divided into two groups: the VR training group (VR group) and the traditional simulation scenario training group (traditional group). The VR Group underwent immersive virtual reality CPR training with interactive feedback, while the Traditional Group received standard simulation-based CPR training using mannequins and instructor guidance. After training, relevant data were collected for comparative analysis. Results The study revealed that the VR group consistently outperforming the traditional group in theoretical knowledge test (cardiac arrest recognition, chest compressions, airway management, and artificial respiration) scores at 1, 3, 6, and 12 months post-training (p < 0.05). Similarly, the VR group showed superior performance in overall skills test scores and individual CPR quality metrics at all post-training assessments. The VR group scored higher in total skills, assessment, post-resuscitation assessment, chest compressions (at 1, 3, and 6 months), airway opening, and artificial respiration compared to the traditional group (p < 0.05). Despite these findings, both groups exhibited a gradual decrease in skills test scores over time. Conclusions Virtual reality training can significantly improve non-medical professional volunteers’ CPR knowledge and skill levels, helping them master and maintain these competencies. However, a decrease in CPR knowledge and skills among the participants over time was observed after VR training, suggesting the need for further retraining sessions.

Long-Term Outcomes of Airway Management in 6 Children With Campomelic Dysplasia.

This case series describes the outcomes of airway management, including airway reconstruction, in 6 patients with campomelic dysplasia and tracheostomy/ventilator dependence secondary to multilevel airway obstruction. Case series and clinical guidelines are provided for the airway management of patients with campomelic dysplasia. Average age of individuals is 19.4 years. Mean follow-up was 12.2 years. Four individuals underwent open airway reconstruction and achieved decannulation. One patient underwent airway reconstruction with improvement of a complete subglottic stenosis but remains ventilator dependent due to severe scoliosis. The remaining 2 patients did not require additional airway reconstruction, have been liberated from ventilator support, and are under evaluation for tracheostomy tube decannulation. Although campomelic dysplasia was historically considered a lethal form of congenital skeletal dysplasia, with many patients succumbing to respiratory failure due to tracheobronchomalacia in the neonatal period, airway reconstruction and long-term survivorship is feasible in children with campomelic dysplasia and significant airway disease.

Impact of airway closure and lung collapse on inhaled nitric oxide effect in acute lung injury: an experimental study

BackgroundEfficacy of inhaled therapy such as Nitric Oxide (iNO) during mechanical ventilation may depend on airway patency. We hypothesized that airway closure and lung collapse, countered by positive end-expiratory pressure (PEEP), influence iNO efficacy. This could support the role of an adequate PEEP titration for inhalation therapy. The main aim of this study was to assess the effect of iNO with PEEP set above or below the airway opening pressure (AOP) generated by airway closure, on hemodynamics and gas exchange in swine models of acute respiratory distress syndrome. Fourteen pigs randomly underwent either bilateral or asymmetrical two-hit model of lung injury. Airway closure and lung collapse were measured with electrical impedance tomography as well as ventilation/perfusion ratio (V/Q). After AOP detection, the effect of iNO (10ppm) was studied with PEEP set randomly above or below regional AOP. Respiratory mechanics, hemodynamics, and gas-exchange were recorded.ResultsAll pigs presented airway closure (AOP > 0.5cmH2O) after injury. In bilateral injury, iNO was associated with an improved mean pulmonary pressure from 49 ± 8 to 42 ± 7mmHg; (p = 0.003), and ventilation/perfusion matching, caused by a reduction in pixels with low V/Q and shunt from 16%[IQR:13–19] to 9%[IQR:4–12] (p = 0.03) only at PEEP set above AOP. iNO had no effect on hemodynamics or gas exchange for PEEP below AOP (low V/Q 25%[IQR:16–30] to 23%[IQR:14–27]; p = 0.68). In asymmetrical injury, iNO improved pulmonary hemodynamics and ventilation/perfusion matching independently from the PEEP set. iNO was associated with improved oxygenation in all cases.ConclusionsIn an animal model of bilateral lung injury, PEEP level relative to AOP markedly influences iNO efficacy on pulmonary hemodynamics and ventilation/perfusion match, independently of oxygenation.

Augmenting patient monitoring during intravenous moderate sedation with artificial intelligence: A pilot study.

A precordial stethoscope (PS) is essential for ensuring clear breath sounds during open airway sedations. However, a traditional PS limits the ability of new users to simultaneously listen to heart and lung sounds alongside experienced practitioners, hindering their learning and development. Bluetooth speaker systems allow for multiple providers but amplify all noise. An artificial intelligence (AI) PS has the potential to selectively reduce ambient noise, allowing multiple providers to monitor concurrently and provides a visual representation of the sound waves.The study looks at the benefits of AI PS in teaching in the dental setting. A questionnaire was created to compare the new AI PS to a conventional PS during intravenous moderate sedation in a dental clinic setting. Sixteen individuals involved in sedations (four dental attendings, seven dental residents, and five dental assistants), were polled with a 100% response rate. 75% of participants agreed that clarity was improved using the AI PS and 81.25% of participants agreed that breath sounds and loudnesswere improved using the AI PS. 93.75% reported the AI PS was beneficial in allowing attendees to concurrently monitor a sedation case alongside dental residents. 100% of assistants reported that the AI PS benefited from their participation in sedation cases. As technology advances, it is important that we as providers continue to evolve and consider implementing AI to improve our ability to monitor patients and enhance educational experiences for dental resident trainees.

The Impact of PEEP on Ventilation Distribution in ARDS.

The first aim of this study was to evaluate the capacity of electrical impedance tomography (EIT) to identify the effect of PEEP on regional ventilation distribution and the regional risk of collapse, overdistention, hypoventilation, and pendelluft in mechanically ventilated patients. The second aim was to evaluate the feasibility of EIT for estimating airway opening pressure (AOP). The EIT signal was recorded both during baseline cyclic ventilation and slow insufflation for one breath for 9 subjects with moderate-to-severe ARDS. From these data, the AOP and volumes insufflated to lung regions with or without the risk of either collapse, overdistention, hypoventilation, or pendelluft were assessed at 3 PEEP levels (5, 10, and 15 cm H2O). PEEP levels were compared by Friedman analysis of variance and the AOP measured by EIT evaluated using an F-test and the Bland and Altman method. The volume for which there was no specific risk significantly decreased at the highest PEEP from 55 ± 31% tidal volume (VT) at PEEP 5 or 82 ± 18% VT at PEEP 10 to 10 ± 30% VT at PEEP 15 (P = .038 between PEEP 5 vs PEEP 15; P = .01 between PEEP 10 vs PEEP 15). The volume associated with overdistention significantly increased with increasing PEEP, whereas that associated with atelectrauma significantly decreased. Pendelluft significantly decreased with increasing PEEP: VT of 8.9 ± 18.6%, 3.6 ± 7.0%, and 3.2 ± 7.1% for PEEP 5, PEEP 10, and PEEP 15, respectively. The center of ventilation tended to increase in the dependent direction with higher PEEP. The AOPs assessed by EIT and from the pressure-volume curve were in good agreement (bias 0.48 cm H2O). Our results suggest that EIT could aid clinicians in making personalized and reasoned choices in setting the PEEP for subjects with ARDS.

Endoscopic recannulation of long-segment, grade IV suprastomal tracheal stenosis: An operative technique

BackgroundLong-segment, grade IV suprastomal tracheal stenosis is rare and difficult to treat (Carpenter et al., 2022 [1]). Patients with grade IV stenosis have significant quality of life impairments since they are tracheostomy dependent and aphonic. Open airway surgery is often needed to improve tracheal patency, restore the patient's voice, and progress towards decannulation (Abouyared et al., 2017 [2]). However, not all patients are candidates for upfront open surgery (Abouyared et al., 2017; Shamji, 2018 [2,3]). Therefore, it is important to develop and refine endoscopic interventions to improve quality of life for these patients. MethodsWe describe a step-by-step endoscopic approach to the recannulation of long-segment, grade IV suprastomal tracheal stenosis. Briefly, our approach utilizes dual (proximal & distal) visualization of the stenosis prior to passing a 25 gauge needle through the stenosis to identify the proper trajectory for recannulation. Then a 16 gauge needle is passed in the same manner, and a wire is placed through the needle and into the distal airway. Once the airway is recannulated, the initial pinpoint opening is gradually widened in Seldinger fashion over the wire with Savary dilators followed by balloon dilation. Finally, a suprastomal L-stent (modified Montgomery T-Tube) is placed to reduce the risk of restenosis (Edwards et al., 2023 [4]). Case discussionA 39-year-old woman with a past medical history significant for poorly controlled type I diabetes mellitus and polysubstance abuse presented with tracheostomy dependence and aphonia. She was diagnosed with a long-segment, grade IV suprastomal tracheal stenosis and initially underwent endoscopic recannulation. This intervention restored her voice and allowed for optimization of her medical conditions before open airway surgery. ConclusionMost patients experience a significant improvement in their quality of life as their voice is typically restored following this procedure. Additionally, individuals who eventually require open airway surgery gain additional time for medical optimization. In our experience, this procedure represents a safe and effective means of extending the utility of traditional endoscopic airway interventions for the management of patients with grade IV stenosis.

Hydrogen combined with tetrandrine attenuates silica-induced pulmonary fibrosis via suppressing NF-kappaB/NLRP3 signaling pathway-mediated epithelial mesenchymal transition and inflammation

Silicosis is a progressive disease characterized by interstitial fibrosis resulting from inhalation of silica particles, and currently lacks specific treatment. Hydrogen (H2) has demonstrated antioxidative, anti-inflammatory, and anti-fibrotic properties, yet its efficacy in treating silicosis remains unexplored. In this study, rats exposed to silica were administered interventions of H2 combined with tetrandrine, and euthanized at 14, 28, and 56 days post-intervention. Lung tissues and serum samples were collected for analysis. Histological examination, MDA assay, enzyme-linked immunosorbent assay, hydroxyproline assay, and Western blotting were employed to assess the impact of H2 combined with tetrandrine on pulmonary fibrosis. The results revealed that this combination significantly alleviated inflammation in silicosis-afflicted rats, effectively suppressed levels of MDA, TNF-α, and IL-1β expression, and inhibited epithelial-mesenchymal transition (EMT), thereby ameliorating pulmonary fibrosis. Notably, protein expression level of E-cadherin was increased，however protein expression levels of vimentin and α-SMA were reduced, and TGF-β were reduced, alongside a significant decrease in hydroxyproline content. Furthermore, H2 combined with tetrandrine downregulated protein expression of NF-κB p65, NF-κB p-p65, Caspase-1, ASC, and NLRP3. These findings substantiate the hypothesis that H2 combined with tetrandrine mitigates inflammation associated with silicosis and suppresses the EMT process to ameliorate fibrosis via the NF-κB/NLRP3 signaling pathway. However, the pressure of airway opening was not assessed in this study and dynamic readings of lung physiological function were not obtained, which is a major limitation of this study.

Evaluating the Quality of Systematic Reviews on Pediatric Sedation in Dentistry: An Umbrella Review.

Sedation is a depression of a patient's state of consciousness, induced by medications, that can reach different levels of intensity during a medical procedure. Conscious sedation produces a minimally depressed level of consciousness without impairment of the ability to maintain an open airway, of protective reflexes or of responses to verbal and physical stimulation. This umbrella review is aimed at critically assessing the available systematic reviews (SRs) and meta-analyses (MA) on sedation in children/adolescents. An electronic database search was conducted that included Pubmed-Medline, Web of Science, Cochrane, Scopus, Scielo, Embase, LILACS and TRIP and the scope of which extended until January 2023. The risk of bias (RoB) of SRs was analyzed using the Measurement Tool to Assess SRs criteria 2 (AMSTAR2). Of 998 entries, 37 SRs were included. In terms of methodological quality, eight studies were assessed as having critically low quality, four studies had low quality, nine studies had moderate quality, and sixteen were considered to be of high quality. Based on the current guidelines, the most employed drugs in pediatric dentistry for sedation are nitrous oxide and midazolam; however, the available evidence supporting their use is insufficient and of low/critically low quality. The combined technique is recommended (nitrous oxide (30-50%) + midazolam). The optimal dose of oral midazolam is 0.75 mg/kg. The level of methodological quality of SRs is expected to increase according to the results and future directions of this umbrella review.

Respiratory and chest wall mechanics in very preterm infants.

Data on static compliance of the chest wall (Ccw) in preterm infants are scarce. We characterized the static compliance of the lung (CL) and Ccw to determine their relative contribution to static compliance of the respiratory system (Crs) in very preterm infants at 36 wk postmenstrual age (PMA). We also aimed to investigate how these compliances were influenced by the presence of bronchopulmonary dysplasia (BPD) and impacted breathing variables. Airway opening pressure, esophageal pressure, and tidal volume (VT) were measured simultaneously during a short apnea evoked by the Hering-Breuer reflex. We computed tidal breathing variables, airway resistance (R), and dynamic lung compliance (CL,dyn), inspiratory capacity (IC), and Crs, CL, and Ccw. Functional residual capacity was assessed by the multiple breath washout technique (FRCmbw). Breathing variables, compliances, and lung volumes were adjusted for body weight. Twenty-three preterm infants born at 27.2 ± 2.0 wk gestational age (GA) were studied at 36.6 ± 0.6 wk PMA. Median and interquartile range (IQR) Crs/kg is 0.69 (0.6), CL/kg 0.95 (1.0), and Ccw/kg 3.0 (2.4). Infants with BPD (n = 11) had lower Crs/kg (P = 0.013), CL/kg (P = 0.019), and Ccw/kg (P = 0.027) compared with infants without BPD. Ccw/CL ratio was equal between groups. FRCmbw/kg (P = 0.044) and IC/kg (P = 0.005) were decreased in infants with BPD. Infants with BPD have reduced static compliance of the respiratory system, the lungs, and chest wall. Decreased Crs, CL, and Ccw in infants with BPD explain the lower FRC and IC seen in these infants.NEW & NOTEWORTHY Data on chest wall compliance in very preterm infants in the postsurfactant era are scarce. To our knowledge, we are the first group to report data on static respiratory system compliance (Crs), lung compliance (CL), and chest wall compliance (Ccw) in preterm infants with and without bronchopulmonary dysplasia (BPD) in the postsurfactant era.

Particles in Exhaled Air (PExA): Clinical Uses and Future Implications.

Access to distal airway samples to assess respiratory diseases is not straightforward and requires invasive procedures such as bronchoscopy and bronchoalveolar lavage. The particles in exhaled air (PExA) device provides a non-invasive means of assessing small airways; it captures distal airway particles (PEx) sized around 0.5-7 μm and contains particles of respiratory tract lining fluid (RTLF) that originate during airway closure and opening. The PExA device can count particles and measure particle mass according to their size. The PEx particles can be analysed for metabolites on various analytical platforms to quantitatively measure targeted and untargeted lung specific markers of inflammation. As such, the measurement of distal airway components may help to evaluate acute and chronic inflammatory conditions such as asthma, chronic obstructive pulmonary disease, acute respiratory distress syndrome, and more recently, acute viral infections such as COVID-19. PExA may provide an alternative to traditional methods of airway sampling, such as induced sputum, tracheal aspirate, or bronchoalveolar lavage. The measurement of specific biomarkers of airway inflammation obtained directly from the RTLF by PExA enables a more accurate and comprehensive understanding of pathophysiological changes at the molecular level in patients with acute and chronic lung diseases.

Opioid-free General Anesthesia and Awake Fiberoptic Intubation with Dexmedetomidine in a Class IV Obese Patient with Cervical Spondylosis

Abstract Patients with Class IV obesity (C4O) (body mass index [BMI] &gt;50 kg/m2) are at a particularly high risk of anesthesia-related complications during the postoperative period, e.g., critical respiratory events (CREs) including respiratory arrest and oversedation, leading to problems with maintaining open airway, hypoxia, and hypercapnia. We present the case of a 67-year-old C4O (BMI 57.2 kg/m2) female patient with cervical spondylosis, scheduled for laparoscopic sleeve gastrectomy. Preanesthesia evaluation revealed hypertension, type 2 diabetes mellitus (DM), nonalcoholic steatohepatitis, and obstructive sleep apnea as comorbidities. Awake fiberoptic intubation was planned because of a high potential for difficult intubation (neck circumference of 45 cm, cervical spondylosis, reduced neck mobility, and type 2 DM), using topical anesthesia and dexmedetomidine (Dex) infusion. General anesthesia was given with desflurane and muscle relaxant. “Opioid-free anesthesia,” wherein use of systemic, neuraxial, or intracavitary opioids is completely eliminated, was maintained with Dex infusion for sedation and analgesia. Reversal of anesthesia was done in Fowler’s position (FP), and after extubation, nasopharyngeal airway connected to high-flow oxygen (10 L/min) via tubing was used, which facilitated spontaneous breathing, maintaining oxygen saturation and uneventful recovery. Postoperatively, intravenous paracetamol alone was adequate for effective pain relief. The patient remained hemodynamically stable throughout the perioperative period. This case underscores the benefits of “opioid-free anesthesia” using intraoperative Dex infusion and efficacious use of nasopharyngeal airway in FP postoperatively, avoiding requirement of ventilator, in supermorbidly obese patients, reducing CREs and optimizing postoperative outcomes.

Treatment of malignant airway obstruction with Y-shape sigma stent loaded with I125 seeds installed via rigid bronchoscopy

PurposeTo summarize and analyze the safety and efficacy of a Y-shape Sigma stent loaded with I125 in patients with inoperable malignant main airway obstruction.MethodsThis study was approved by the Institutional Ethics Committee, and a written informed consent was obtained from each participant. A Y-shape Sigma stent loaded with I125 was placed under vision from rigid bronchoscopy. The primary endpoint was alleviation of symptoms and improvement of Karnofsky Performance Status (KPS) score, and the secondary endpoint was complications and technical success.ResultsFrom November 2018 through June 2023, total 33 patients with malignant airway obstruction were palliatively treated by installing Y-shape Sigma stents loaded with I125. The airway lumen was immediately restored and the average airway opening significantly increased to 70 ± 9.4% after the procedure from baseline 30.2 ± 10.5% (p < 0.05). Average KPS score was improved from baseline 30.0 ± 10.0 to 70.0 ± 10.0 (p < 0.05) as well as PaO2 from baseline 50.1 ± 15.4 mmHg to 89.3 ± 8.6 mmHg (p < 0.05). The technical success rate of placing the stent in this study was 73%, and adverse events or complications including bleeding, I125 loss, and airway infection occurred during or after the procedure.ConclusionPlacement of Y-shape Sigma stents under vision from rigid bronchoscopy in the patients with malignant airway obstruction is feasible and it immediately alleviates dyspnea and significantly improves quality of life.

Exploring alveolar recruitability using positive end-expiratory pressure in mice overexpressing TGF-β1: a structure–function analysis

Pre-injured lungs are prone to injury progression in response to mechanical ventilation. Heterogeneous ventilation due to (micro)atelectases imparts injurious strains on open alveoli (known as volutrauma). Hence, recruitment of (micro)atelectases by positive end-expiratory pressure (PEEP) is necessary to interrupt this vicious circle of injury but needs to be balanced against acinar overdistension. In this study, the lung-protective potential of alveolar recruitment was investigated and balanced against overdistension in pre-injured lungs. Mice, treated with empty vector (AdCl) or adenoviral active TGF-β1 (AdTGF-β1) were subjected to lung mechanical measurements during descending PEEP ventilation from 12 to 0 cmH2O. At each PEEP level, recruitability tests consisting of two recruitment maneuvers followed by repetitive forced oscillation perturbations to determine tissue elastance (H) and damping (G) were performed. Finally, lungs were fixed by vascular perfusion at end-expiratory airway opening pressures (Pao) of 20, 10, 5 and 2 cmH2O after a recruitment maneuver, and processed for design-based stereology to quantify derecruitment and distension. H and G were significantly elevated in AdTGF-β1 compared to AdCl across PEEP levels. H was minimized at PEEP = 5–8 cmH2O and increased at lower and higher PEEP in both groups. These findings correlated with increasing septal wall folding (= derecruitment) and reduced density of alveolar number and surface area (= distension), respectively. In AdTGF-β1 exposed mice, 27% of alveoli remained derecruited at Pao = 20 cmH2O. A further decrease in Pao down to 2 cmH2O showed derecruitment of an additional 1.1 million alveoli (48%), which was linked with an increase in alveolar size heterogeneity at Pao = 2–5 cmH2O. In AdCl, decreased Pao resulted in septal folding with virtually no alveolar collapse. In essence, in healthy mice alveoli do not derecruit at low PEEP ventilation. The potential of alveolar recruitability in AdTGF-β1 exposed mice is high. H is optimized at PEEP 5–8 cmH2O. Lower PEEP folds and larger PEEP stretches septa which results in higher H and is more pronounced in AdTGF-β1 than in AdCl. The increased alveolar size heterogeneity at Pao = 5 cmH2O argues for the use of PEEP = 8 cmH2O for lung protective mechanical ventilation in this animal model.

Adverse pregnancy outcomes and pharyngeal flow limitation during sleep: Nulliparous Pregnancy Outcomes Study Monitoring Mothers-to-be (nuMoM2b).

Pharyngeal flow limitation during pregnancy may be a risk factor for adverse pregnancy outcomes but was previously challenging to quantify. Our objective was to determine whether a novel objective measure of flow limitation identifies an increased risk of pre-eclampsia (primary outcome) and other adverse outcomes in a prospective cohort: Nulliparous Pregnancy Outcomes Study Monitoring Mothers-to-be (nuMoM2b). Flow limitation severity scores (0%=fully obstructed, 100%=open airway), quantified from breath-by-breath airflow shape, were obtained from home sleep tests during early (6-15 weeks) and mid (22-31 weeks) pregnancy. Multivariable logistic regression quantified associations between flow limitation (median overnight severity, both time-points averaged) and pre-eclampsia, adjusting for maternal age, body mass index (BMI), race, ethnicity, chronic hypertension and flow limitation during wakefulness. Secondary outcomes were hypertensive disorders of pregnancy (HDP), gestational diabetes mellitus (GDM) and infant birthweight. Of 1939 participants with flow limitation data at both time-points (mean±sd age 27.0±5.4 years and BMI 27.7±6.1 kg·m-2), 5.8% developed pre-eclampsia, 12.7% developed HDP and 4.5% developed GDM. Greater flow limitation was associated with increased pre-eclampsia risk: adjusted OR 2.49 (95% CI 1.69-3.69) per 2sd increase in severity. Findings persisted in women without sleep apnoea (apnoea-hypopnoea index <5 events·h-1). Flow limitation was associated with HDP (OR 1.77 (95% CI 1.33-2.38)) and reduced infant birthweight (83.7 (95% CI 31.8-135.6) g), but not GDM. Greater flow limitation is associated with increased risk of pre-eclampsia, HDP and lower infant birthweight. Flow limitation may provide an early target for mitigating the consequences of sleep disordered breathing during pregnancy.

Accuracy of respiratory muscle assessments to predict weaning outcomes: a systematic review and comparative meta-analysis

BackgroundSeveral bedside assessments are used to evaluate respiratory muscle function and to predict weaning from mechanical ventilation in patients on the intensive care unit. It remains unclear which assessments perform best in predicting weaning success. The primary aim of this systematic review and meta-analysis was to summarize and compare the accuracy of the following assessments to predict weaning success: maximal inspiratory (PImax) and expiratory pressures, diaphragm thickening fraction and excursion (DTF and DE), end-expiratory (Tdiee) and end-inspiratory (Tdiei) diaphragm thickness, airway occlusion pressure (P0.1), electrical activity of respiratory muscles, and volitional and non-volitional assessments of transdiaphragmatic and airway opening pressures.MethodsMedline (via Pubmed), EMBASE, Web of Science, Cochrane Library and CINAHL were comprehensively searched from inception to 04/05/2023. Studies including adult mechanically ventilated patients reporting data on predictive accuracy were included. Hierarchical summary receiver operating characteristic (HSROC) models were used to estimate the SROC curves of each assessment method. Meta-regression was used to compare SROC curves. Sensitivity analyses were conducted by excluding studies with high risk of bias, as assessed with QUADAS-2. Direct comparisons were performed using studies comparing each pair of assessments within the same sample of patients.ResultsNinety-four studies were identified of which 88 studies (n = 6296) reporting on either PImax, DTF, DE, Tdiee, Tdiei and P0.1 were included in the meta-analyses. The sensitivity to predict weaning success was 63% (95% CI 47–77%) for PImax, 75% (95% CI 67–82%) for DE, 77% (95% CI 61–87%) for DTF, 74% (95% CI 40–93%) for P0.1, 69% (95% CI 13–97%) for Tdiei, 37% (95% CI 13–70%) for Tdiee, at fixed 80% specificity. Accuracy of DE and DTF to predict weaning success was significantly higher when compared to PImax (p = 0.04 and p < 0.01, respectively). Sensitivity and direct comparisons analyses showed that the accuracy of DTF to predict weaning success was significantly higher when compared to DE (p < 0.01).ConclusionsDTF and DE are superior to PImax and DTF seems to have the highest accuracy among all included respiratory muscle assessments for predicting weaning success. Further studies aiming at identifying the optimal threshold of DTF to predict weaning success are warranted.Trial registration: PROSPERO CRD42020209295, October 15, 2020.

Open airway surgery for post-COVID laryngotracheal stenosis

IntroductionThis study reports our experience with open reconstructive surgery in patients with laryngotracheal stenosis (LTS) following prolonged intubation and/or tracheostomy in the context of COVID-19.MethodsAll patients underwent a preoperative endoscopic airway assessment. Posterior glottic lesions were graded according to the Bogdasarian classification, subglottic-tracheal lesions according to the Cotton-Myers classification and postoperative complications reported by the Clavien–Dindo classification. We report postoperative outcomes and functional results in this patient subset.ResultsWe include 14 patients diagnosed to have post COVID LTS, one female and 13 males. This group was compared with a control group, diagnosed with LTS following prolonged intubation. In the COVID group, mean age of patients at the time of the airway surgery was 52.1 ± 16.8 years (range: 13.7–76.3). More than half the patients were multi-morbid with hypertension and obesity being the most common conditions. Eleven patients had multi-site stenoses. Open surgical interventions performed were tracheal resection and anastomosis, laryngotracheal reconstruction and extended cricotracheal resection, and postoperative complications were seen in 12 (85.6%) patients. 70% patients with pre-existing tracheostomy were decannulated. Oral swallowing was not tolerated in one-fifth of the patients and a significant number of them have poor voice quality.ConclusionPost-COVID pandemic, airway surgeons are seeing an increased number of patients with complex LTS, and we report significant postoperative complications in this patient subset. Decannulation rates, voice and swallowing results are poor in patients with glottic involvement as compared to isolated tracheal stenosis.

Timing of Complications in Open Airway Reconstruction.

Tracheal resection (TR) and cricotracheal resection (CTR) are performed for patients with airway stenosis, tracheal tumor, and tracheoesophageal fistula. Post-operative complications include airway edema requiring reintubation, hematoma, anastomotic dehiscence, restenosis, and death. Although these complications and associated risk factors have been well described, the time where clinical suspicion should be highest post operatively has not been characterized. Patients who underwent TR or CTR at a single center between 2015 and 2022 were reviewed. Variables including demographics and comorbidities were recorded. Rate, nature, and time in days of post-operative complications were evaluated. Sixty-nine cases were reviewed. Average patient age was 46.8 years old and 63.8% were male. The average follow-up period was 625 ± 724 days. 19 (27.5%) patients experienced one or more major complications including four (5.8%) who died. Eight (11.6%) patients required reintubation and 4 (5.8%) patients underwent revision tracheostomy. Most complications occurred within 8 days of surgery. Restenosis was noted an average of 42.6 days after surgery, with no new restenosis occurring after 3 months. In this single-center study, most post-operative complications after TR or CTR, including hematoma and anastomotic dehiscence, occurred within 8 days post-operatively. Restenosis was noted approximately 1-3 months after surgery. This may inform clinical decision-making regarding patient monitoring and surveillance after open airway surgery. 4 Laryngoscope, 134:3527-3531, 2024.