Effect of perioperative sigh ventilation on postoperative hypoxemia and pulmonary complications after on-pump cardiac surgery (E-SIGHT): study protocol for a randomized controlled trial.

BACKGROUND: Postoperative hypoxemia and pulmonary complications remain a frequent event after on-pump cardiac surgery and mostly characterized by pulmonary atelectasis. Surfactant dysfunction or hyposecretion happens prior to atelectasis formation, and sigh represents the strongest stimulus for surfactant secretion. The role of sigh breaths added to conventional lung protective ventilation in reducing postoperative hypoxemia and pulmonary complications among cardiac surgery is unknown. METHODS: The perioperative sigh ventilation in cardiac surgery (E-SIGHT) trial is a single-center, two-arm, randomized controlled trial. In total, 192 patients scheduled for elective cardiac surgery with cardiopulmonary bypass (CPB) and aortic cross-clamp will be randomized into one of the two treatment arms. In the experimental group, besides conventional lung protective ventilation, sigh volumes producing plateau pressures of 35 cmH2O (or 40 cmH2O for patients with body mass index > 35 kg/m2) delivered once every 6 min from intubation to extubation. In the control group, conventional lung protective ventilation without preplanned recruitment maneuvers is used. Lung protective ventilation (LPV) consists of low tidal volumes (6-8 mL/kg of predicted body weight) and positive end-expiratory pressure (PEEP) setting according to low PEEP/FiO2 table for acute respiratory distress syndrome (ARDS). The primary endpoint is time-weighted average SpO2/FiO2 ratio during the initial post-extubation hour. Main secondary endpoint is the severity of postoperative pulmonary complications (PPCs) computed by postoperative day 7. DISCUSSION: The E-SIGHT trial will be the first randomized controlled trial to evaluate the impact of perioperative sigh ventilation on the postoperative outcomes after on-pump cardiac surgery. The trial will introduce and assess a novel perioperative ventilation approach to mitigate the risk of postoperative hypoxemia and PPCs in patients undergoing cardiac surgery. Also provide the basis for a future larger trial aiming at verifying the impact of sigh ventilation on postoperative pulmonary complications. TRIAL REGISTRATION: ClinicalTrials.gov NCT06248320. Registered on January 30, 2024. Last updated February 26, 2024.

Evaluation of a new hyperbaric oxygen ventilator during pressure-controlled ventilation.

Introduction: The stability of a new hyperbaric ventilator (Shangrila590, Beijing Aeonmed Company, Beijing, China) at different clinically relevant pressures in a hyperbaric chamber during pressure-controlled ventilation (PCV) was investigated. Methods: The ventilator was connected to a test lung in the multiplace hyperbaric chamber. The inspiratory pressure (PI) of the ventilator was set to 1.0, 1.5, 2.0, 2.5 and 3.0 kPa (approximately 10, 15, 20, 25 and 30 cmH2O). The compliance and resistance of the test lung were set to 200 mL·kPa⁻¹ and 2 kPa·L⁻¹·s⁻¹, respectively. Experiments were conducted at 101, 203 and 284 kPa ambient pressure (1.0, 2.0 and 2.8 atmospheres absolute respectively). At each of the 5 PI values, the tidal volume (VT), peak inspiratory pressure (Ppeak) and peak inspiratory flow (Fpeak) displayed by the ventilator and the test lung were recorded for 20 cycles. Test lung data were considered the actual ventilation values. The ventilation data were compared among the three groups to evaluate the stability of the ventilator. Results: At every PI, the Ppeak detected by the ventilator decreased slightly with increasing ambient pressure. The Fpeak values measured by the test lung decreased substantially as the ambient pressure increased. Nevertheless, the reduction in VT at 284 kPa and PI 30 cmH2O (compared to performance at 101 kPa) was comparatively small (approximately 60 ml). Conclusions: In PCV mode this ventilator provided relatively stable VT across clinically relevant PI values to ambient pressures as high as 284 kPa. However, because Fpeak decreases at higher ambient pressure, some user adjustment might be necessary for precise VT maintenance during clinical use at higher PIs and ambient pressures.

Efficacy of respiratory support therapies during pulmonary rehabilitation exercise training in chronic obstructive pulmonary disease patients: a systematic review and network meta-analysis.

BACKGROUND: Exercise training is fundamental in pulmonary rehabilitation (PR), but patients with chronic obstructive pulmonary disease (COPD) often struggle with exercise intolerance. Respiratory support during exercise in COPD patients may be a beneficial adjunct therapy. In this study, the effect of different respiratory support therapy during pulmonary rehabilitation exercise training in COPD patients was assessed through a network meta-analysis. METHODS: Five databases were searched to obtain randomized controlled trials involving different respiratory support therapies during PR exercise training in COPD patients. The Cochrane Handbook tool was employed to assess the risk bias of included studies. Network meta-analysis was performed using the STATA software. The study protocol was registered at PROSPERO (CRD42023491139). RESULTS: A total of 35 studies involving 1321 patients and 6 different interventions were included. Network meta-analysis showed that noninvasive positive pressure ventilation (NPPV) is superior in improving exercise capacity (6-Minute Walk Test distance, peak work rate, endurance time), dyspnea, and physiological change (peak VO2, tidal volume, minute ventilation and lactate level) in stable COPD patients who were at GOLD stage III or IV during PR exercise training. The final surface under the cumulative ranking curve value indicated that NPPV therapy achieved the best assistive rehabilitation effect. CONCLUSIONS: The obtained results indicate that NPPV is most powerful in assisting exercise in severe COPD patients under stable condition. Researchers should focus more on the safety, feasibility, and personalization of interventions. Furthermore, there is a need for additional high-quality trials to assess the consistency of evidence across various respiratory support approaches. TRIAL REGISTRATION: The study was registered at PROSPERO (CRD42023491139).

Optimal Positive End-expiratory Pressure Levels in Tuberculosis-associated Acute Respiratory Distress Syndrome.

BACKGROUND: The objective is to assess lung compliance and identify the optimal positive end-expiratory pressure (PEEP) levels in patients with tuberculosis-associated Acute Respiratory Distress Syndrome (TB-ARDS) compared to non-TB-ARDS patients. METHODS: This observational case-control study utilized electrical impedance tomography to evaluate lung mechanics in 20 TB-ARDS and 20 non-TB-ARDS patients. Participants underwent PEEP titration from 23 to 5 cm H2O in 2 cm H2O decrements. Lung compliance and the rates of hyperdistention and collapse were assessed at each PEEP level. RESULTS: Delta impedance values showed higher amounts in a PEEP range of 11-17 cm H2O and in patients with TB-ARDS (P > 0.05). In addition, both hyperdistention and collapse rates were nonsignificantly higher in TB-ARDS patients (P > 0.05), and the compromised levels of hyperdistention and collapse rates were at 15-17 cm H2O, indicating the most favorable PEEP level. CONCLUSIONS: The observed patterns of hyperdistention and collapse rates across various PEEP levels provide valuable insights into the susceptibility of TB-ARDS patients to barotrauma. Notably, the identified optimal PEEP range between 15 and 17 cm H2O may guide ventilator management strategies in mitigating both hyperdistention and collapse; nonetheless, due to the high variability of lung compliances within groups, we strongly recommend individualized consideration for tailored respiratory support and evaluation.

Acute renal response to changes in carbon dioxide in mechanically ventilated female pigs.

Kidney response to acute and mechanically induced variation in ventilation associated with different levels of PEEP has not been investigated. We aimed to quantify the effect of ventilatory settings on renal acid-base compensation. Forty-one pigs undergoing hypo- (<0.2 Lkg-1 min-1, PEEP 25 cmH2O), intermediate (0.2-0.4 Lkg-1 min-1 with either PEEP 5 or 25 cmH2O), or hyper-ventilation (>0.4 Lkg-1 min-1, PEEP 5 cmH2O) for 48 h were retrospectively included. The decrease in pH paralleled the decrease in plasma strong ion difference (SID) in hyper- and intermediately ventilated groups with lower PEEP. In contrast, the plasma SID remained nearly constant in hypo- and intermediately ventilated groups with higher PEEP. Changes in plasma chloride concentration accounted for the changes in plasma SID (conditional R2 = 0.86). The plasma SID changes were paralleled by mirror changes in urinary SID. Higher PEEP (25 cmH2O), compared to lower PEEP (5 cmH2O) dampened or abolished the renal compensation through its effect on hemodynamics (higher central venous and mean pulmonary pressures), irrespective of minute ventilation. During mechanical ventilation, the compensatory renal response to respiratory derangement is immediate and progressive but can be dampened by high PEEP levels.

[Evidence-based nursing practice for the prevention of nasal and facial pressure injuries in patients with non-invasive positive pressure ventilation].

OBJECTIVE: To investigate the evidence-based practice of prevention and care of nasal and facial pressure injuries in patients with non-invasive positive pressure ventilation (NPPV) using the knowledge to action framework (KTA), and to explore its effectiveness. METHODS: Using an evidence-based nursing approach, an evidence-based practice group was established to formulate a clinical problem, the literature from domestic and international databases were researched for relevant evidence, the evidence was introduced into clinical scenarios, an evidence-based practice plan was developed, and a strategy for applying the best evidence was constructed by conducting a baseline review of healthcare professionals and patients with NPPV, analyzing barriers and promoting factors, and making changes in clinical practice at the organizational level, the practitioner level, and the patient level. Purposive sampling method was used to select the healthcare staff of the cardiac surgical intensive care unit (CSICU) of the Shandong Provincial Hospital Affiliated to Shandong First Medical University, as well as the patients with NPPV admitted from October 1 to November 15, 2023 (pre-evidence-based practice) and November 16 to December 31 (post-evidence-based practice), as the subjects of the study. Through questionnaire analysis, the incidence of nasal and facial pressure injury of NPPV patients, the implementation rate of review indicators of medical staff, the score of the knowledge, belief and conduct of medical staff, and the compliance and comfort of patients before and after evidence-based practice were compared. RESULTS: A total of 52 medical staff were included, aged (28.54±6.50) years old, with 3.00 (1.00, 12.75) years of working experience; 2 doctoral degree holders (3.85%), 4 master degree holders (7.69%), 46 bachelor degree holders (88.46%); 2 with senior title (3.85%), 17 with intermediate title (32.69%), and 33 junior titles (63.46%). Fifty patient questionnaires were collected before and after evidence-based nursing practice; the differences between before and after evidence-based practice in terms of gender, age, body weight, duration of ventilator usage, 24-hour bleeding and total bleeding were not statistically significant and were comparable. Compared with the pre-evidence-based practice, after carrying out the corresponding evidence-based nursing practice, the incidence of nasal and facial pressure injuries of NPPV patients decreased from 16.00% (8/50) to 4.00% (2/50, P < 0.05), the total implementation rate of review indicators of medical staff increased from 79.73% to 94.08% (P < 0.01), and the total scores of knowledge, belief and conduct were significantly improved (141.96±13.88 vs. 114.65±19.72, P < 0.05), and compliance and comfort of patients were significantly improved (compliance score: 4.60±0.99 vs. 5.82±1.42, comfort score: 4.10±1.63 vs. 6.92±2.33, both P < 0.05). CONCLUSIONS: The application of an evidence-based nursing approach to obtain evidence related to the prevention of nasal and facial pressure injuries in patients with NPPV can be used to guide clinical practice, significantly reducing the incidence of nasal and facial pressure injuries in such patients, improving the implementation rate of review indicators and the knowledge, belief, and conduct scores of medical staff, and enhancing compliance and comfort of NPPV patients.

[Design and simulation study of positive pressure ventilation system in a simulated human biological lung].

Simulation of the human biological lung is a crucial method for medical professionals to learn and practice the use of new pulmonary interventional diagnostic and therapeutic devices. The study on ventilation effects of the simulation under positive pressure ventilation mode provide valuable guidance for clinical ventilation treatment. This study focused on establishing an electrical simulation ventilation model, which aims to address the complexities in parameter configuration and slow display of air pressure and airflow waveforms in simulating the human biological lung under positive pressure ventilation mode. A simulated ventilation experiment was conducted under pressure-regulated volume control (PRVC) positive pressure ventilation mode, and the resulting ventilation waveform was compared with that of normal adults. The experimental findings indicated that the average error of the main reference index moisture value was 9.8% under PRVC positive pressure ventilation mode, effectively simulating the ventilatory effect observed in normal adults. So the established electrical simulation ventilation model is feasible, and provides a foundation for further research on the simulation of human biological lung positive pressure ventilation experimental platform.

Speed of lung inflation at birth influences the initiation of lung injury in preterm lambs.

Gas flow is fundamental for driving tidal ventilation and, thus, the speed of lung motion, but current bias flow settings to support the preterm lung after birth do not have an evidence base. We aimed to determine the role of gas bias flow rates to generate positive pressure ventilation in initiating early lung injury pathways in the preterm lamb. Using slower speeds to inflate the lung during tidal ventilation (gas flow rates 4-6 L/min) did not affect lung mechanics, mechanical power, or gas exchange compared with those currently used in clinical practice (8-10 L/min). Speed of pressure and volume change during inflation were faster with higher flow rates. Lower flow rates resulted in less bronchoalveolar fluid protein, better lung morphology, and fewer detached epithelial cells. Overall, relative to unventilated fetal controls, there was greater protein change using 8-10 L/min, which was associated with enrichment of acute inflammatory and innate responses. Slowing the speed of lung motion by supporting the preterm lung from birth with lower flow rates than in current clinical use resulted in less lung injury without compromising tidal ventilation or gas exchange.

Comparing oxygen therapies for hypoxemia prevention during gastrointestinal endoscopy under procedural sedation: A systematic review and network meta-analysis.

STUDY OBJECTIVE: Hypoxemia is the most frequent adverse event observed during gastrointestinal endoscopy under procedural sedation. An optimum oxygen therapy has still not been conclusively determined. DESIGN: A systematic review and network meta-analysis of randomized clinical trials. SETTING: Digestive Endoscopy Center. PATIENTS: Adults (≥18 years old and of both sexes) during gastrointestinal endoscopy under procedural sedation. INTERVENTIONS: Pubmed, MEDLINE, Web of Science, Embase, and Clinicaltrials.gov. were searched until June 30, 2023. Randomized clinical trials (RCTs) comparing any oxygen therapy with another oxygen therapy or with placebo (nasal cannula, NC) were included. MEASUREMENT: The primary outcome was the incidence of hypoxemia, defined as the pulse oxygen saturation (SpO2). Random-effects network meta-analyses were performed. Data are reported as odds ratios (OR), prediction intervals (PrI) and 95% CI. Bias risk was evaluated following the guidelines outlined by the Cochrane Collaboration. The quality of evidence was evaluated through the Grading of Recommendations Assessment, Development and Evaluation (GRADE) framework. MAIN RESULTS: We included 27 RCTs with a total of 7552 patients. Compared to the use of NC, non-invasive positive pressure ventilation (NIPPV) demonstrated superior efficacy in mitigating hypoxemia (NIPPV vs. NC, OR = 0.16, 95% CI: 0.08-0.31, 95% PrI: 0.06-0.41), followed by Wei nasal jet tube (WNJT) (WNJT vs. NC, OR = 0.17, 95% CI: 0.10-0.30, 95% PrI: 0.07-0.42). The efficacy for preventing hypoxemia was ranked as follows: NIPPV > WNJT > oropharynx/nasopharyngeal catheter > high-flow nasal oxygenation > nasal mask > NC. CONCLUSIONS: During gastrointestinal endoscopy under procedural sedation, all other advanced oxygen therapies were found to be more efficacious than nasal cannula. NIPPV and WNJT appear to be the most efficacious oxygen therapy for preventing hypoxemia. Additionally, clinicians should make a choice regarding the most suitable oxygen therapy based on the risk population, type of endoscopy and adverse events.

Recruitment-to-inflation ratio to assess response to PEEP during laparoscopic surgery: A physiologic study.

STUDY OBJECTIVE: During laparoscopic surgery, the role of PEEP to improve outcome is controversial. Mechanistically, PEEP benefits depend on the extent of alveolar recruitment, which prevents ventilator-induced lung injury by reducing lung dynamic strain. The hypotheses of this study were that pneumoperitoneum-induced aeration loss and PEEP-induced recruitment are inter-individually variable, and that the recruitment-to-inflation ratio (R/I) can identify patients who benefit from PEEP in terms of strain reduction. DESIGN: Sequential study. SETTING: Operating room. PATIENTS: Seventeen ASA I-III patients receiving robot-assisted prostatectomy during Trendelenburg pneumoperitoneum. INTERVENTIONS AND MEASUREMENTS: Patients underwent end-expiratory lung volume (EELV) and respiratory/lung/chest wall mechanics (esophageal manometry and inspiratory/expiratory occlusions) assessment at PEEP = 0 cmH2O before and after pneumoperitoneum, at PEEP = 4 and 12 cmH2O during pneumoperitoneum. Pneumoperitoneum-induced derecruitment and PEEP-induced recruitment were assessed through a simplified method based on multiple pressure-volume curve. Dynamic and static strain changes were evaluated. R/I between 12 and 4 cmH2O was assessed from EELV. Inter-individual variability was rated with the ratio of standard deviation to mean (CoV). MAIN RESULTS: Pneumoperitoneum reduced EELV by (median [IqR]) 410 mL [80-770] (p < 0.001) and increased dynamic strain by 0.04 [0.01-0.07] (p < 0.001), with high inter-individual variability (CoV = 70% and 88%, respectively). Compared to PEEP = 4 cmH2O, PEEP = 12 cmH2O yielded variable amount of recruitment (139 mL [96-366] CoV = 101%), causing different extent of dynamic strain reduction (median decrease 0.02 [0.01-0.04], p = 0.002; CoV = 86%) and static strain increases (median increase 0.05 [0.04-0.07], p = 0.01, CoV = 33%). R/I (1.73 [0.58-3.35]) estimated the decrease in dynamic strain (p ≤0.001, r = -0.90) and the increase in static strain (p = 0.009, r = -0.73) induced by PEEP, while PEEP-induced changes in respiratory and lung mechanics did not. CONCLUSIONS: Trendelenburg pneumoperitoneum yields variable derecruitment: PEEP capability to revert these phenomena varies significantly among individuals. High R/I identifies patients in whom higher PEEP mostly reduces dynamic strain with limited static strain increases, potentially allowing individualized settings.

Positive end-expiratory pressure management in patients with severe ARDS: implications of prone positioning and extracorporeal membrane oxygenation.

The optimal strategy for positive end-expiratory pressure (PEEP) titration in the management of severe acute respiratory distress syndrome (ARDS) patients remains unclear. Current guidelines emphasize the importance of a careful risk-benefit assessment for PEEP titration in terms of cardiopulmonary function in these patients. Over the last few decades, the primary goal of PEEP usage has shifted from merely improving oxygenation to emphasizing lung protection, with a growing focus on the individual pattern of lung injury, lung and chest wall mechanics, and the hemodynamic consequences of PEEP. In moderate-to-severe ARDS patients, prone positioning (PP) is recommended as part of a lung protective ventilation strategy to reduce mortality. However, the physiologic changes in respiratory mechanics and hemodynamics during PP may require careful re-assessment of the ventilation strategy, including PEEP. For the most severe ARDS patients with refractory gas exchange impairment, where lung protective ventilation is not possible, veno-venous extracorporeal membrane oxygenation (V-V ECMO) facilitates gas exchange and allows for a "lung rest" strategy using "ultraprotective" ventilation. Consequently, the importance of lung recruitment to improve oxygenation and homogenize ventilation with adequate PEEP may differ in severe ARDS patients treated with V-V ECMO compared to those managed conservatively. This review discusses PEEP management in severe ARDS patients and the implications of management with PP or V-V ECMO with respect to respiratory mechanics and hemodynamic function.

Predictors for prescription of noninvasive ventilation in the postoperative period of cardiac surgery: a systematic review.

INTRODUCTION: The postoperative (PO) period after cardiac surgery is associated with the occurrence of respiratory complications. Noninvasive positive pressure ventilation (NIPPV) is largely used as a ventilatory support strategy after the interruption of invasive mechanical ventilation. However, the variables associated with NIPPV prescription are unclear. OBJECTIVE: To describe the literature on predictors of NIPPV prescription in patients during the PO period of cardiac surgery. MATERIALS AND METHODS: This systematic review was registered on the International Prospective Register of Systematic Reviews (PROSPERO) platform in December 2021 (CRD42021291973). Bibliographic searches were performed in February 2022 using the PubMed, Lilacs, Embase and PEDro databases, with no year or language restrictions. The Predictors for the prescription of NIPPV were considered among patients who achieved curative NIPPV. RESULTS: A total of 349 articles were identified, of which four were deemed eligible and were included in this review. Three studies were retrospective studies, and one was a prospective safety pilot study. The total sample size in each study ranged from 109 to 1657 subjects, with a total of 3456 participants, of whom 283 realized NIPPV. Curative NIPPV was the only form of NIPPV in 75% of the studies, which presented this form of prescription in 5-9% of the total sample size, with men around 65 years old being the majority of the participants receiving curative NIPPV. The main indication for curative NIPPV was acute respiratory failure. Only one study realized prophylactic NIPPV (28% of 32 participants). The main predictors for the prescription of curative NIPPV in the PO period of cardiac surgery observed in this study were elevated body mass index (BMI), hypercapnia, PO lung injury, cardiogenic oedema and pneumonia. CONCLUSIONS: BMI and lung alterations related to gas exchange disturbances are major predictors for NIPPV prescription in patients during the PO period of cardiac surgery. The identification of these predictors can benefit clinical decision-making regarding the prescription of NIPPV and help conserve human and material resources, thereby preventing the indiscriminate use of NIPPV.

Mechanical ventilation guided by driving pressure optimizes local pulmonary biomechanics in an ovine model.

Mechanical ventilation exposes the lung to injurious stresses and strains that can negatively affect clinical outcomes in acute respiratory distress syndrome or cause pulmonary complications after general anesthesia. Excess global lung strain, estimated as increased respiratory system driving pressure, is associated with mortality related to mechanical ventilation. The role of small-dimension biomechanical factors underlying this association and their spatial heterogeneity within the lung are currently unknown. Using four-dimensional computed tomography with a voxel resolution of 2.4 cubic millimeters and a multiresolution convolutional neural network for whole-lung image segmentation, we dynamically measured voxel-wise lung inflation and tidal parenchymal strains. Healthy or injured ovine lungs were evaluated as the mechanical ventilation positive end-expiratory pressure (PEEP) was titrated from 20 to 2 centimeters of water. The PEEP of minimal driving pressure (PEEPDP) optimized local lung biomechanics. We observed a greater rate of change in nonaerated lung mass with respect to PEEP below PEEPDP compared with PEEP values above this threshold. PEEPDP similarly characterized a breaking point in the relationships between PEEP and SD of local tidal parenchymal strain, the 95th percentile of local strains, and the magnitude of tidal overdistension. These findings advance the understanding of lung collapse, tidal overdistension, and strain heterogeneity as local triggers of ventilator-induced lung injury in large-animal lungs similar to those of humans and could inform the clinical management of mechanical ventilation to improve local lung biomechanics.

[Artificial ventilation in patients with stroke: main results of the Russian multicenter observational clinical trial RETAS]. / Iskusstvennaya ventilyatsiya legkikh u patsientov s ostrym narusheniem mozgovogo krovoobrashcheniya: osnovnye rezul'taty Rossiiskogo mnogotsentrovogo observatsionnogo klinicheskogo issledovaniya RETAS.

OBJECTIVE: To analyze the relationship between the characteristics of respiratory support (RS) for patients with stroke and clinical factors with the number and structure of complications, deaths, and length of stay in the intensive care unit (ICU) and duration of artificial pulmonary ventilation (ALV). MATERIAL AND METHODS: The Russian multicenter observational clinical study «Respiratory Therapy for Acute Stroke¼ (RETAS) that enrolled 1289 patients with stroke requiring RS was conducted under the auspices of the All-Russian public organization «Federation of Anesthesiologists and Resuscitators¼. Indications for ALV, the use of hyperventilation, the maximum level of positive end-expiratory pressure, starting modes of mechanical ventilation, timing of tracheostomy, the incidence of protein-energy malnutrition (PEM) and infectious complications were analyzed. The following scales were used to assess the severity of the condition: the National Institutes of Health Stroke Severity Scale (NIHSS), the Glasgow Coma Scale, the Glasgow Outcome Scale (GOS). RESULTS: For the group of patients with a stroke severity of more than 20 NIHSS points, the mortality increase was associated with initial hypoxia (p=0.004), hyperventilation used to relieve intracranial hypertension (p=0.034), and starting ventilation with volume control (VC) compared with starting pressure-controlled ventilation (PC) (p<0.001). We found that the use of the instrumental monitoring of intracranial pressure was associated with a decrease in mortality (p<0.001). The absence of PEM in patients with stroke is associated with a higher probability of a positive outcome (GOS 4 and 5) for the group with NIHSS less than 14 points (p<0.001). Ventilator-associated tracheobronchitis and ventilator-associated pneumonia were associated with an increase in the duration of ALV, the duration of weaning from the ventilator (for ventilator-associated tracheobronchitis) and the duration of stay in the ICU, and also reduced the chances of favorable outcomes (p<0.05). CONCLUSION: The factors associated with increased mortality in acute stroke are: hypoxemia at the start of ALV, hyperventilation, starting ventilation with VC in comparison with starting ventilation with PC, the use of only clinical methods of monitoring intracranial pressure in comparison with instrumental monitoring. The adverse effect of PEM and infectious complications on the outcome in patients with acute stroke has been proven.

Comparison between Air-Q Self Pressurized Airway Device with Blocker and Proseal Laryngeal Mask Airway in anesthetized paralyzed adult female patients undergoing elective gynecological operations.

INTRODUCTION: The Air-Q Self Pressurized Airway Device with Blocker (SP Blocker) was compared to the Proseal Laryngeal Mask Airway (PLMA) during positive pressure ventilation regarding the primary outcome (oropharyngeal leak pressure [OLP]), secondary outcomes (peak inspiratory pressure [PIP], inspired tidal volume [ITV], expired tidal volume [ETV], leak volume [LV] and leak fraction [LF]), insertion time, ventilation score, fiber-optic glottis view score, and postoperative laryngopharyngeal parameters (LPM). MATERIAL AND METHODS: Adult healthy female patients scheduled for elective gynecological laparotomies under general anesthesia using controlled mechanical ventilation were recruited to a prospective randomized comparative clinical trial. Exclusion criteria were body mass index (BMI) ≥ 35 kg m -2 , El-Ganzouri score ≥ 5, upper airway problems, hiatus hernia or pregnancy. Patients were classified into an SP Blocker group ( n = 75) and a PLMA group ( n = 75). Primary and secondary outcomes were assessed initially and at fixed time points after successful insertion of devices. RESULTS: Initially after successful device insertion: the SP Blocker group showed statistically significant higher mean OLP (cmH 2 O) (29.46 ± 2.11 vs. 28.06 ± 1.83 respectively; 95% CI: -2.037 to -0.76, P < 0.0001), lower mean PIP (cmH 2 O) (15.49 ± 0.61 vs. 17.78 ± 1.04 respectively; 95% CI: 2.02 to 2.56, P < 0.0001), higher mean ITV (mL) (411 ± 30 vs. 403 ± 15 respectively; 95% CI: -15.65 to -0.347, P = 0.041), higher mean ETV (mL) (389 ± 12 vs. 354 ± 11 respectively; 95% CI: -38.72 to -31.29, P < 0.0001), lower mean LV (mL) (22 ± 18 vs. 49 ± 10 respectively; 95% CI: 22.3 to 31.7, P < 0.0001) and lower mean LF (%) (5 ± 2.04 vs. 12 ± 6.8 respectively; 95% CI: 5.38 to 8.62, P < 0.0001) than the PLMA group. Mean insertion time (seconds) was shorter in the SP Blocker group than the PLMA group (16.39 ± 2.81 vs. 18.63 ± 3.44 respectively; 95% CI: 1.23 to 3.25, P < 0.0001). The SP Blocker group offered a better fiber-optic glottis view score than the PLMA group without differences concerning ventilation score and LPM. CONCLUSIONS: SP Blocker provided as safe anesthesia during controlled mechanical ventilation as PLMA.

Comparing physiological impacts of positive pressure ventilation versus self-breathing via a versatile cardiopulmonary model incorporating a novel alveoli opening mechanism.

Mathematical models can be used to generate high-fidelity simulations of the cardiopulmonary system. Such models, when applied to real patients, can provide valuable insights into underlying physiological processes that are hard for clinicians to observe directly. In this work, we propose a novel modelling strategy capable of generating scenario-specific cardiopulmonary simulations to replicate the vital physiological signals clinicians use to determine the state of a patient. This model is composed of a tree-like pulmonary system that features a novel, non-linear alveoli opening strategy, based on the dynamics of balloon inflation, that interacts with the cardiovascular system via the thorax. A baseline simulation of the model is performed to measure the response of the system during spontaneous breathing which is subsequently compared to the same system under mechanical ventilation. To test the new lung opening mechanics and systematic recruitment of alveolar units, a positive end-expiratory pressure (PEEP) test is performed and its results are then compared to simulations of a deep spontaneous breath. The system displays a marked decrease in tidal volume as PEEP increases, replicating a sigmoidal curve relationship between volume and pressure. At high PEEP, cardiovascular function is shown to be visibly impaired, in contrast to the deep breath test where normal function is maintained.

The ventilator of the future: key principles and unmet needs.

Persistent shortcomings of invasive positive pressure ventilation make it less than an ideal intervention. Over the course of more than seven decades, clinical experience and scientific investigation have helped define its range of hazards and limitations. Apart from compromised airway clearance and lower airway contamination imposed by endotracheal intubation, the primary hazards inherent to positive pressure ventilation may be considered in three broad categories: hemodynamic impairment, potential for ventilation-induced lung injury, and impairment of the respiratory muscle pump. To optimize care delivery, it is crucial for monitoring and machine outputs to integrate information with the potential to impact the underlying requirements of the patient and/or responses of the cardiopulmonary system to ventilatory interventions. Trending analysis, timely interventions, and closer communication with the caregiver would limit adverse clinical trajectories. Judging from the rapid progress of recent years, we are encouraged to think that insights from physiologic research and emerging technological capability may eventually address important aspects of current deficiencies.

Optimizing Positive End-Expiratory Pressure Based on Intra-Abdominal Pressure in Patients with Acute Respiratory Failure.

BACKGROUND: Positive end-expiratory pressure (PEEP) is a crucial component of mechanical ventilation to improve oxygenation in critically ill patients with respiratory failure. The interaction between abdominal and thoracic compartment pressures is known well. Especially in intra-abdominal hypertension, lower PEEP may cause atelectotrauma by repetitive opening and closing of alveoli. AIM: In this study, it was aimed to investigate the effect of PEEP adjustment according to the intra-abdominal pressure (IAP) on oxygenation and clarify possible harms. METHOD: Patients older than 18 were mechanically ventilated due to hypoxemic respiratory failure and had normal IAP (<15 mmHg) included in the study. Patients with severe cardiovascular dysfunction were excluded. The following PEEP levels were applied: PEEPzero of 0 cmH2O, PEEPIAP/2 = 50% of IAP, and PEEPIAP = 100% of IAP. After a 30-minute equilibration period, arterial blood gases and mean arterial pressures were measured. RESULTS: One hundred thirty-eight patients (mean age 66.5 ± 15.9, 56.5% male) enrolled on the study. The mean IAP was 9.8 ± 3.4. Seventy-nine percent of the patients' PaO2/FiO2 ratio was under 300 mmHg. Figure 1 shows the change in PaO2/FiO2 ratio, PaCO2, PPlato, and MAP of the patients according to the PEEP levels. Overall increases were detected in the PaO2/FiO2 ratio (P < 0.001) and Pplato (P < 0.001), while PaCO2 and MAP did not change after increasing PEEP gradually. Pairwise analyses revealed differences in PaO2/FiO2 between PEEPzero (186.4 [85.7-265.8]) and PEEPIAP/2 (207.7 [101.7-292.9]) (t = -0.77, P < 0.001), between baseline and PEEPIAP (236.1 [121.4-351.0]) (t = -1.7, P < 0.001), and between PEEPIAP/2 and PEEPIAP (t = -1.0, P < 0.001). Plato pressures were in the safe range (<30 cmH2O) at all three PEEP levels (PEEPzero = 12 [10-15], PEEPIAP/2 = 15 [13-18], PEEPIAP = 17 [14-22]). CONCLUSION: In patients with acute hypoxemic respiratory failure and mechanically ventilated, PEEP adjustment according to the IAB improves oxygenation, especially in the settings of the limited source where other PEEP titration methods are absent.