Without artificial airway though oral, nasal or airway incision, the bi-level positive airway pressure (Bi-PAP) has been widely employed for respiratory patients. In an effort to investigate the therapeutic effects and measures for the respiratory patients under the noninvasive Bi-PAP ventilation, a therapy system model was designed for virtual ventilation experiments. In this system model, it includes a sub-model of noninvasive Bi-PAP respirator, a sub-model of respiratory patient, and a sub-model of the breath circuit and mask. And based on the Matlab Simulink, a simulation platform for the noninvasive Bi-PAP therapy system was developed to conduct the virtual experiments in simulated respiratory patient with no spontaneous breathing (NSB), chronic obstructive pulmonary disease (COPD) and acute respiratory distress syndrome (ARDS). The simulated outputs such as the respiratory flows, pressures, volumes, etc, were collected and compared to the outputs which were obtained in the physical experiments with the active servo lung. By statistically analyzed with SPSS, the results demonstrated that there was no significant difference ( P > 0.1) and was in high similarity ( R > 0.7) between the data collected in simulations and physical experiments. The therapy system model of noninvasive Bi-PAP is probably applied for simulating the practical clinical experiment, and maybe conveniently applied to study the technology of noninvasive Bi-PAP for clinicians.
Humans ; Respiration, Artificial/methods* ; Positive-Pressure Respiration/methods* ; Respiration ; Ventilators, Mechanical ; Lung

Acute respiratory distress syndrome (ARDS) continues to be one of the most life-threatening conditions for patients in the intensive care unit (ICU). The 2023 European Society of Intensive Care Medicine guidelines on ARDS: definition, phenotyping and respiratory support strategies (2023 Guideline) update the 2017 An Official American Thoracic Society/European Society of Intensive Care Medicine/Society of Critical Care Medicine clinical practice guideline: mechanical ventilation in adult patients with ARDS (2017 Guideline), including 7 aspects of 3 topics of definitions, phenotyping, and respiratory support strategies [including high flow nasal cannula oxygen (HFNO), non-invasive ventilation (NIV), neuromuscular blocking agents (NMBA), extracorporeal life support (ECLS), positive end-expiratory pressure (PEEP) with recruitment maneuvers (RM), tidal volume (VT), and prone positioning]. 2023 Guideline review and summarize the literature since the publication of the 2017 Guideline, covering ARDS and acute hypoxemic respiratory failure, as well as ARDS caused by novel coronavirus infection. Based on the most recent medical evidence, the 2023 Guideline provide clinicians with new ideas and approaches for nonpharmacologic respiratory support strategies for adults with ARDS. This article provides interpretation of the new concepts, the new approaches, the new recommended grading and new levels of evidence for ARDS in the 2023 Guideline.
Adult ; Humans ; COVID-19 ; Respiration, Artificial ; Positive-Pressure Respiration ; Respiratory Distress Syndrome/therapy* ; Noninvasive Ventilation

OBJECTIVE: To find out the circuit pressure and flow at the trigger point by observing the characteristics of the inspiratory trigger waveform of the ventilator, confirm the intra-alveolar pressure as the index to reflect the effort of the trigger according to the working principle of the ventilator combined with the laws of respiratory mechanics, establish the related mathematical formula, and analyze its influencing factors and logical relationship. METHODS: A test-lung was connected to the circuit in a PB840 ventilator and a SV600 ventilator set in pressure-support mode. The positive end-expiratory pressure (PEEP) was set at 5 cmH₂O (1 cmH₂O ≈ 0.098 kPa), and the wall of test-lung was pulled outwards till an inspiratory was effectively triggered separately in slow, medium, fast power, and separately in flow-trigger mode (sensitivity V_Trig 3 L/min, 5 L/min) and pressure-trigger mode (sensitivity P_Trig 2 cmH₂O, 4 cmH₂O). By adjusting the scale of the curve in the ventilator display, the loop pressure and flow corresponding to the trigger point under different triggering conditions were observed. Taking intraalveolar pressure (Pa) as the research object, the Pa (called P_a-T) needed to reach the effective trigger time (T_T) was analyzed in the method of respiratory mechanics, and the amplitude of pressure change (ΔP) and the time span (ΔT) of Pa during triggering were also analyzed. RESULTS: (1) Corresponding relationship between pressure and flow rate at TT time: in flow-trigger mode, in slow, medium and fast trigger, the inhalation flow rate was V_Trig, and the circuit pressure was separately PEEP, PEEP-Pn, and PEEP-Pn' (Pn, Pn', being the decline range, and Pn' > Pn). In pressure-trigger mode, the inhalation flow rate was 1 L/min (PB840 ventilator) or 2 L/min (SV600 ventilator), and the circuit pressure was PEEP-P_Trig. (2) Calculation of P_a-T: in flow-trigger mode, in slow trigger: P_a-T = PEEP-V_TrigR (R represented airway resistance). In medium trigger: P_a-T = PEEP-Pn-V_TrigR. In fast trigger: P_a-T = PEEP-Pn'-V_TrigR. In pressure-trigger mode: P_a-T = PEEP-P_Trig-1R. (3) Calculation of ΔP: in flow trigger mode, in flow trigger: without intrinsic PEEP (PEEPi), ΔP = V_TrigR; with PEEPi, ΔP = PEEPi-PEEP+V_TrigR. In medium trigger: without PEEPi, ΔP = Pn+V_TrigR; with PEEPi, ΔP = PEEPi-PEEP+Pn+V_TrigR. In fast trigger: without PEEPi, ΔP = Pn'+V_TrigR; with PEEPi, ΔP = PEEPi-PEEP+Pn'+V_TrigR. In pressure-trigger mode, without PEEPi, ΔP = P_Trig+1R; with PEEPi, ΔP = PEEPi-PEEP+P_Trig+1R. (4) Pressure time change rate of Pa (F_P): F_P = ΔP/ΔT. In the same ΔP, the shorter the ΔT, the greater the triggering ability. Similarly, in the same ΔT, the bigger the ΔP, the greater the triggering ability. The FP could better reflect the patient's triggering ability. CONCLUSIONS The patient's inspiratory effort is reflected by three indicators: the minimum intrapulmonary pressure required for triggering, the pressure span of intrapulmonary pressure, and the pressure time change rate of intrapulmonary pressure, and formula is established, which can intuitively present the logical relationship between inspiratory trigger related factors and facilitate clinical analysis.
Humans ; Respiration, Artificial/methods* ; Positive-Pressure Respiration ; Lung ; Ventilators, Mechanical ; Respiratory Mechanics

Mechanical ventilation has, since its introduction into clinical practice, undergone a major evolution from controlled ventilation to diverse modes of assisted ventilation. Conventional mechanical ventilators depend on flow sensors and pneumatic pressure and controllers to complete the respiratory cycle. Neurally adjusted ventilatory assist (NAVA) is a new form of assisted ventilation in recent years, which monitors the electrical activity of the diaphragm (EAdi) to provide an appropriately level of pressure support. And EAdi is the best available signal to sense central respiratory drive and trigger ventilatory assist. Unlike other ventilation modes, NAVA breathing instructions come from the center. Therefore, NAVA have the synchronous nature of the breaths and the patient-adjusted nature of the support. Compared with traditional ventilation mode, NAVA can efficiently unload respiratory muscles, relieve the risk of ventilator-induced lung injury (VILI), improve patient-ventilator coordination, enhance gas exchange, increase the success rate of weaning, etc. This article reviews the research progress of NAVA in order to provide theoretical guidance for clinical applications.
Humans ; Interactive Ventilatory Support ; Respiration, Artificial ; Positive-Pressure Respiration ; Diaphragm/physiology* ; Respiratory Muscles/physiology*

Neurocritical care (NCC) is not only generally guided by principles of general intensive care, but also directed by specific goals and methods. This review summarizes the common pulmonary diseases and pathophysiology affecting NCC patients and the progress made in strategies of respiratory support in NCC. This review highlights the possible interactions and pathways that have been revealed between neurological injuries and respiratory diseases, including the catecholamine pathway, systemic inflammatory reactions, adrenergic hypersensitivity, and dopaminergic signaling. Pulmonary complications of neurocritical patients include pneumonia, neurological pulmonary edema, and respiratory distress. Specific aspects of respiratory management include prioritizing the protection of the brain, and the goal of respiratory management is to avoid inappropriate blood gas composition levels and intracranial hypertension. Compared with the traditional mode of protective mechanical ventilation with low tidal volume (Vt), high positive end-expiratory pressure (PEEP), and recruitment maneuvers, low PEEP might yield a potential benefit in closing and protecting the lung tissue. Multimodal neuromonitoring can ensure the safety of respiratory maneuvers in clinical and scientific practice. Future studies are required to develop guidelines for respiratory management in NCC.
Humans ; Lung ; Lung Diseases/etiology* ; Positive-Pressure Respiration/methods* ; Respiration, Artificial/adverse effects* ; Tidal Volume

Mechanical ventilation is an importmant life-sustaining treatment for patients with acute respiratory distress syndrome. Its clinical outcomes depend on patients' characteristics of lung recruitment. Estimation of lung recruitment characteristics is valuable for the determination of ventilatory maneurvers and ventilator parameters. There is no easily-used, bedside method to assess lung recruitment characteristics. The present paper proposed a method to estimate lung recruitment characteristics from the static pressure-volume curve of lungs. The method was evaluated by comparing with published experimental data. Results of lung recruitment derived from the presented method were in high agreement with the published data, suggesting that the proposed method is capable to estimate lung recruitment characteristics. Since some advanced ventilators are capable to measure the static pressure-volume curve automatedly, the presented method is potential to be used at bedside, and it is helpful for clinicians to individualize ventilatory manuevers and the correpsonding ventilator parameters.
Humans ; Lung ; Positive-Pressure Respiration ; Respiration, Artificial ; Respiratory Distress Syndrome ; Ventilators, Mechanical

Treatment-emergent central sleep apnea (TECSA) is a specific form of sleep-disordered breathing, characterized by the emergence or persistence of central apneas during treatment for obstructive sleep apnea. The purpose of this review was to summarize the definition, epidemiology, potential mechanisms, clinical characteristics, and treatment of TECSA. We searched for relevant articles up to January 31, 2020, in the PubMed database. The prevalence of TECSA varied widely in different studies. The potential mechanisms leading to TECSA included ventilatory control instability, low arousal threshold, activation of lung stretch receptors, and prolonged circulation time. TECSA may be a self-limited disorder in some patients and could be resolved spontaneously over time with ongoing treatment of continuous positive airway pressure (CPAP). However, central apneas persist even with the regular CPAP therapy in some patients, and new treatment approaches such as adaptive servo-ventilation may be necessary. We concluded that several questions regarding TECSA remain, despite the findings of many studies, and it is necessary to carry out large surveys with basic scientific design and clinical trials for TECSA to clarify these irregularities. Further, it will be vital to evaluate the baseline demographic and polysomnographic data of TECSA patients more carefully and comprehensively.
Continuous Positive Airway Pressure ; Humans ; Lung ; Respiration ; Sleep Apnea, Central/therapy* ; Sleep Apnea, Obstructive

OBJECTIVE: This study summarizes and compares clinical and laboratory characteristics of 34 patients admitted to the intensive care unit (ICU) for complications from coronavirus disease 2019 (COVID-19) at the First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China from Jan. 22 to Mar. 5, 2020. METHODS: A total of 34 patients were divided into two groups, including those who required noninvasive ventilation (NIV) and invasive mechanical ventilation (IMV) with additional extracorporeal membrane oxygenation (ECMO) in 11 patients. Clinical features of COVID-19 patients were described and the parameters of clinical characteristics between the two groups were compared. RESULTS: The rates of the acute cardiac and kidney complications were higher in IMV cases than those in NIV cases. Most patients had lymphocytopenia on admission, with lymphocyte levels dropping progressively on the following days, and the more severe lymphopenia developed in the IMV group. In both groups, T lymphocyte counts were below typical lower limit norms compared to B lymphocytes. On admission, both groups had higher than expected amounts of plasma interleukin-6 (IL-6), which over time declined more in NIV patients. The prothrombin time was increased and the levels of platelet, hemoglobin, blood urea nitrogen (BUN), D-dimer, lactate dehydrogenase (LDH), and IL-6 were higher in IMV cases compared with NIV cases during hospitalization. CONCLUSIONS Data showed that the rates of complications, dynamics of lymphocytopenia, and changes in levels of platelet, hemoglobin, BUN, D-dimer, LDH and IL-6, and prothrombin time in these ICU patients were significantly different between IMV and NIV cases.
Acute Kidney Injury ; virology ; Aged ; Aged, 80 and over ; Betacoronavirus ; Blood Urea Nitrogen ; China ; Coronavirus Infections ; complications ; therapy ; Extracorporeal Membrane Oxygenation ; Female ; Fibrin Fibrinogen Degradation Products ; analysis ; Heart Diseases ; virology ; Hemoglobins ; analysis ; Hospitalization ; Humans ; Intensive Care Units ; Interleukin-6 ; blood ; L-Lactate Dehydrogenase ; blood ; Lymphopenia ; virology ; Male ; Middle Aged ; Noninvasive Ventilation ; Pandemics ; Pneumonia, Viral ; complications ; therapy ; Positive-Pressure Respiration ; Prothrombin Time ; Retrospective Studies

Betacoronavirus ; Cannula ; Coronavirus Infections ; prevention & control ; therapy ; transmission ; Humans ; Pandemics ; prevention & control ; Pneumonia, Viral ; prevention & control ; therapy ; transmission ; Positive-Pressure Respiration ; Risk Factors

OBJECTIVE: To investigate the effect of inverse ratio ventilation (IRV) combined with positive end-expiratory pressure (PEEP) in infants undergoing thoracoscopic surgery with single lung ventilation (OLV) for lung cystadenomas. METHODS: A total of 66 infants undergoing thoracoscopic surgery with OLV for lung cystadenomas in our hospital from February, 2018 to February, 2019 were randomized into conventional ventilation groups (group N, =33) and inverse ventilation group (group R, =33). Hemodynamics and respiratory parameters of the infants were recorded and arterial blood gas analysis was performed at 15 min after two lung ventilation (TLV) (T), OLV30 min (T), OLV60 min (T), and 15 min after recovery of TLV (T). Bronchoalveolar lavage fluid was collected before and after surgery to detect the expression level of advanced glycation end product receptor (RAGE). RESULTS: Sixty-three infants were finally included in this study. At T and T, Cdyn, PaO and OI in group R were significantly higher ( < 0.05) and Ppeak, PaCO and PA-aO were significantly lower than those in group N ( < 0.05). There was no significant difference in HR or MAP between the two groups at T and T ( > 0.05). The level of RAGE significantly increased after the surgery in both groups ( < 0.05), and was significantly lower in R group than in N group ( < 0.05). CONCLUSIONS In infants undergoing thoracoscopic surgery with OLV for pulmonary cystadenoma, appropriate IRV combined with PEEP does not affect hemodynamic stability and can increases pulmonary compliance, reduce the peak pressure, and improve oxygenation to provide pulmonary protection.
Cystadenoma ; surgery ; Humans ; Infant ; Lung ; surgery ; One-Lung Ventilation ; Positive-Pressure Respiration ; Thoracoscopy ; Treatment Outcome