Lung ultrasound score evaluation of the effect of pressure-controlled ventilation volume-guaranteed on patients undergoing laparoscopic-assisted radical gastrectomy.

BACKGROUND: Laparoscopic-assisted radical gastrectomy (LARG) is the standard treatment for early-stage gastric carcinoma (GC). However, the negative impact of this procedure on respiratory function requires the optimized intraoperative management of patients in terms of ventilation. AIM: To investigate the influence of pressure-controlled ventilation volume-guaranteed (PCV-VG) and volume-controlled ventilation (VCV) on blood gas analysis and pulmonary ventilation in patients undergoing LARG for GC based on the lung ultrasound score (LUS). METHODS: The study included 103 patients with GC undergoing LARG from May 2020 to May 2023, with 52 cases undergoing PCV-VG (research group) and 51 cases undergoing VCV (control group). LUS were recorded at the time of entering the operating room (T0), 20 minutes after anesthesia with endotracheal intubation (T1), 30 minutes after artificial pneumoperitoneum (PP) establishment (T2), and 15 minutes after endotracheal tube removal (T5). For blood gas analysis, arterial partial pressure of oxygen (PaO2) and partial pressure of carbon dioxide (PaCO2) were observed. Peak airway pressure (Ppeak), plateau pressure (Pplat), mean airway pressure (Pmean), and dynamic pulmonary compliance (Cdyn) were recorded at T1 and T2, 1 hour after PP establishment (T3), and at the end of the operation (T4). Postoperative pulmonary complications (PPCs) were recorded. Pre- and postoperative serum interleukin (IL)-1ß, IL-6, and tumor necrosis factor-α (TNF-α) were measured by enzyme-linked immunosorbent assay. RESULTS: Compared with those at T0, the whole, anterior, lateral, posterior, upper, lower, left, and right lung LUS of the research group were significantly reduced at T1, T2, and T5; in the control group, the LUS of the whole and partial lung regions (posterior, lower, and right lung) decreased significantly at T2, while at T5, the LUS of the whole and some regions (lateral, lower, and left lung) increased significantly. In comparison with the control group, the whole and regional LUS of the research group were reduced at T1, T2, and T5, with an increase in PaO2, decrease in PaCO2, reduction in Ppeak at T1 to T4, increase in Pmean and Cdyn, and decrease in Pplat at T4, all significant. The research group showed a significantly lower incidence of PPCs than the control group within 3 days postoperatively. Postoperative IL-1ß, IL-6, and TNF-α significantly increased in both groups, with even higher levels in the control group. CONCLUSION: LUS can indicate intraoperative non-uniformity and postural changes in pulmonary ventilation under PCV-VG and VCV. Under the lung protective ventilation strategy, the PCV-VG mode more significantly improved intraoperative lung ventilation in patients undergoing LARG for GC and reduced lung injury-related cytokine production, thereby alleviating lung injury.

Continuous estimation of respiratory system compliance and airway resistance during pressure-controlled ventilation without end-inspiration occlusion.

BACKGROUND: Assessing mechanical properties of the respiratory system (Cst) during mechanical ventilation necessitates an end-inspiration flow of zero, which requires an end-inspiratory occlusion maneuver. This lung model study aimed to observe the effect of airflow obstruction on the accuracy of respiratory mechanical properties during pressure-controlled ventilation (PCV) by analyzing dynamic signals. METHODS: A Hamilton C3 ventilator was attached to a lung simulator that mimics lung mechanics in healthy, acute respiratory distress syndrome (ARDS) and chronic obstructive pulmonary disease (COPD) models. PCV and volume-controlled ventilation (VCV) were applied with tidal volume (VT) values of 5.0, 7.0, and 10.0 ml/kg. Performance characteristics and respiratory mechanics were assessed and were calibrated by virtual extrapolation using expiratory time constant (RCexp). RESULTS: During PCV ventilation, drive pressure (DP) was significantly increased in the ARDS model. Peak inspiratory flow (PIF) and peak expiratory flow (PEF) gradually declined with increasing severity of airflow obstruction, while DP, end-inspiration flow (EIF), and inspiratory cycling ratio (EIF/PIF%) increased. Similar estimated values of Crs and airway resistance (Raw) during PCV and VCV ventilation were obtained in healthy adult and mild obstructive models, and the calculated errors did not exceed 5%. An underestimation of Crs and an overestimation of Raw were observed in the severe obstruction model. CONCLUSION: Using the modified dynamic signal analysis approach, respiratory system properties (Crs and Raw) could be accurately estimated in patients with non-severe airflow obstruction in the PCV mode.

A Retrospective Cohort Study of the Impact of Implementing Volume-Targeted Compared to Pressure-Limited Ventilation in a Single-Center, Level III Neonatal Intensive Care Unit in Oman.

Background The use of volume-targeted ventilation (VTV) in neonatology has been introduced in the last decade. This study was performed to determine the impact of clinical implementation of volume-targeted conventional mechanical ventilation using the volume guarantee mode in mechanical ventilation of all neonates needing mechanical ventilation compared to pressure-limited ventilation (PLV) modes. The mortality rate, duration of mechanical ventilation, and bronchopulmonary dysplasia were the primary outcomes of the study. Methodology This retrospective cohort study was conducted at a level III-VI neonatal intensive care unit (NICU) within a tertiary academic hospital in Oman. All intubated neonates admitted to the NICU within two time periods, i.e., the PLV cohort: January 2011 to December 2013 (three years), and the VTV cohort: January 2017 to December 2019 (three years), were eligible for inclusion in the study. Neonates were excluded if they had multiple congenital anomalies, tracheostomy, and those with a Do Not Resuscitate status. A predetermined data set was collected retrospectively from electronic records. The PLV and VTV cohorts were compared, and SPSS version 25 (IBM Corp., Armonk, NY, USA) was used for data analysis. Results A total of 290 neonates were included (PLV: n = 138, and VTV: n = 152). The two cohorts were statistically similar in their baseline characteristics, including gestational age, birth weight, Apgar scores, indications for mechanical ventilation, age at intubation, need for surfactant therapy, and age at extubation. The VTV cohort had a significantly lower mortality rate (n (%) = 10 (6.6%) vs. 21 (15.3%), p = 0.02). An insignificant trend of lower duration of ventilation was observed in the VTV cohort (34.5 vs. 50.5 hours, p = 0.24). There was no significant difference in bronchopulmonary dysplasia (16 (21.3%) vs. 12 (17.8%), p = 0.18). VTV was associated with a significant reduction in pulmonary hemorrhage (1 (0.7%) vs. 8 (5.7%), p = 0.04), episodes of hypocapnia (2 vs. 3/patient, p = 0.04), and episodes of hypercapnia (0 vs 1/patient, p = 0.04). Conclusions The implementation of VTV in clinical practice in our level III-VI NICU was associated with significant advantages, including reduction in mortality, pulmonary hemorrhage, and episodes of hypercapnia and hypocapnia. A large prospective, randomized, and multicenter trial is recommended to confirm these findings.

Flow-controlled ventilation decreases mechanical power in postoperative ICU patients.

BACKGROUND: Mechanical power (MP) is the energy delivered by the ventilator to the respiratory system and combines factors related to the development of ventilator-induced lung injury (VILI). Flow-controlled ventilation (FCV) is a new ventilation mode using a constant low flow during both inspiration and expiration, which is hypothesized to lower the MP and to improve ventilation homogeneity. Data demonstrating these effects are scarce, since previous studies comparing FCV with conventional controlled ventilation modes in ICU patients suffer from important methodological concerns. OBJECTIVES: This study aims to assess the difference in MP between FCV and pressure-controlled ventilation (PCV). Secondary aims were to explore the effect of FCV in terms of minute volume, ventilation distribution and homogeneity, and gas exchange. METHODS: This is a physiological study in post-cardiothoracic surgery patients requiring mechanical ventilation in the ICU. During PCV at baseline and 90 min of FCV, intratracheal pressure, airway flow and electrical impedance tomography (EIT) were measured continuously, and hemodynamics and venous and arterial blood gases were obtained repeatedly. Pressure-volume loops were constructed for the calculation of the MP. RESULTS: In 10 patients, optimized FCV versus PCV resulted in a lower MP (7.7 vs. 11.0 J/min; p = 0.004). Although FCV did not increase overall ventilation homogeneity, it did lead to an improved ventilation of the dependent lung regions. A stable gas exchange at lower minute volumes was obtained. CONCLUSIONS: FCV resulted in a lower MP and improved ventilation of the dependent lung regions in post-cardiothoracic surgery patients on the ICU. Trial registration Clinicaltrials.gov identifier: NCT05644418. Registered 1 December 2022, retrospectively registered.

Nocturnal Pressure Controlled Ventilation Improves Sleep Efficiency in Patients Receiving Mechanical Ventilation.

BACKGROUND: Patients receiving mechanical ventilation commonly experience sleep fragmentation. The present meta-analysis compared the effects of pressure controlled ventilation (PCV) and pressure support ventilation (PSV) on sleep quality. METHODS: We conducted a search of the PubMed, Embase, and Cochrane Library databases for studies published before November 2023. In this meta-analysis, individual effect sizes were standardized, and the pooled effect size was determined by using random-effects models. The primary outcome was sleep efficiency. The secondary outcomes were wakefulness, percentages of REM (rapid eye movement) sleep and stages 3 and 4 non-REM sleep, the fragmentation index, and the incidence of apneic events. RESULTS: This meta-analysis examined 4 trials that involved 67 subjects. Sleep efficiency was significantly higher in the PCV group than in the PSV group (mean difference 15.57%, 95% CI 8.54%-22.59%). Wakefulness was significantly lower in the PCV group than in the PSV group (mean difference -18.67%, 95% CI -30.29% to -7.04%). The percentage of REM sleep was significantly higher in the PCV group than in the PSV group (mean difference 2.32%, 95% CI 0.20%-4.45%). Among the subjects with a tendency to develop sleep apnea, the fragmentation index was significantly lower in those receiving PCV than PSV (mean difference -40.00%, 95% CI -51.12% to -28.88%). The incidence of apneic events was significantly lower in the PCV group than in the PSV group (risk ratio 0.06, 95% CI 0.01-0.45). CONCLUSIONS: Compared with PSV, PCV may improve sleep quality in patients receiving nocturnal mechanical ventilation.

Individualised flow-controlled ventilation reduces applied mechanical power and improves ventilation efficiency in a porcine intra-abdominal hypertension model.

BACKGROUND: Aim of this study was to evaluate feasibility and effects of individualised flow-controlled ventilation (FCV), based on compliance guided pressure settings, compared to standard of pressure-controlled ventilation (PCV) in a porcine intra-abdominal hypertension (IAH) model. The primary aim of this study was to investigate oxygenation. Secondary aims were to assess respiratory and metabolic variables and lung tissue aeration. METHODS: Pigs were randomly assigned to FCV (n = 9) and PCV (n = 9). IAH was induced by insufflation of air into the abdomen to induce IAH grades ranging from 0 to 3. At each IAH grade FCV was undertaken using compliance guided pressure settings, or PCV (n = 9) was undertaken with the positive end-expiratory pressure titrated for maximum compliance and the peak pressure set to achieve a tidal volume of 7 ml/kg. Gas exchange, ventilator settings and derived formulas were recorded at two timepoints for each grade of IAH. Lung aeration was assessed by a computed tomography scan at IAH grade 3. RESULTS: All 18 pigs (median weight 54 kg [IQR 51-67]) completed the observation period of 4 h. Oxygenation was comparable at each IAH grade, but a significantly lower minute volume was required to secure normocapnia in FCV at all IAH grades (7.6 vs. 14.4, MD - 6.8 (95% CI - 8.5 to - 5.2) l/min; p < 0.001). There was also a significant reduction of applied mechanical power being most evident at IAH grade 3 (25.9 vs. 57.6, MD - 31.7 (95% CI - 39.7 to - 23.7) J/min; p < 0.001). Analysis of Hounsfield unit distribution of the computed tomography scans revealed a significant reduction in non- (5 vs. 8, MD - 3 (95% CI - 6 to 0) %; p = 0.032) and poorly-aerated lung tissue (7 vs. 15, MD - 6 (95% CI - 13 to - 3) %, p = 0.002) for FCV. Concomitantly, normally-aerated lung tissue was significantly increased (84 vs. 76, MD 8 (95% CI 2 to 15) %; p = 0.011). CONCLUSIONS: Individualised FCV showed similar oxygenation but required a significantly lower minute volume for CO2-removal, which led to a remarkable reduction of applied mechanical power. Additionally, there was a shift from non- and poorly-aerated lung tissue to normally-aerated lung tissue in FCV compared to PCV.

Six methods to determine expiratory time constants in mechanically ventilated patients: a prospective observational physiology study.

BACKGROUND: Expiratory time constant (τ) objectively assesses the speed of exhalation and can guide adjustments of the respiratory rate and the I:E ratio with the goal of achieving complete exhalation. Multiple methods of obtaining τ are available, but they have not been compared. The purpose of this study was to compare six different methods to obtain τ and to test if the exponentially decaying flow corresponds to the measured time constants. METHODS: In this prospective study, pressure, flow, and volume waveforms of 30 postoperative patients undergoing volume (VCV) and pressure-controlled ventilation (PCV) were obtained using a data acquisition device and analyzed. τ was measured as the first 63% of the exhaled tidal volume (VT) and compared to the calculated τ as the product of expiratory resistance (RE) and respiratory system compliance (CRS), or τ derived from passive flow/volume waveforms using previously published equations as proposed by Aerts, Brunner, Guttmann, and Lourens. We tested if the duration of exponentially decaying flow during exhalation corresponded to the duration of the predicted second and third τ, based on multiples of the first measured τ. RESULTS: Mean (95% CI) measured τ was 0.59 (0.57-0.62) s and 0.60 (0.58-0.63) s for PCV and VCV (p = 0.45), respectively. Aerts method showed the shortest values of all methods for both modes: 0.57 (0.54-0.59) s for PCV and 0.58 (0.55-0.61) s for VCV. Calculated (CRS * RE) and Brunner's τ were identical with mean τ of 0.64 (0.61-0.67) s for PCV and 0.66 (0.63-069) s for VCV. Mean Guttmann's τ was 0.64 (0.61-0.68) in PCV and 0.65 (0.62-0.69) in VCV. Comparison of each τ method between PCV and VCV was not significant. Predicted time to exhale 95% of the VT (i.e., 3*τ) was 1.77 (1.70-1.84) s for PCV and 1.80 (1.73-1.88) s for VCV, which was significantly longer than measured values: 1.27 (1.22-1.32) for PCV and 1.30 (1.25-1.35) s for VCV (p < 0.0001). The first, the second and the third measured τ were progressively shorter: 0.6, 0.4 and 0.3 s, in both ventilation modes (p < 0.0001). CONCLUSION: All six methods to determine τ show similar values and are feasible in postoperative mechanically ventilated patients in both PCV and VCV modes.

Zonal demand-controlled ventilation strategy to minimize infection probability and energy consumption: A coordinated control based on occupant detection.

Due to the outbreak of COVID-19, an increased risk of airborne transmission has been experienced in buildings, particularly in confined public places. The need for ventilation as a means of infection prevention has become more pronounced given that some basic precautions (like wearing masks) are no longer mandatory. However, ventilating the space as a whole (e.g., using a unified ventilation rate) may lead to situations where there is either insufficient or excessive ventilation in localized areas, potentially resulting in localized virus accumulation or large energy consumption. It is of urgent need to investigate real-time control of ventilation systems based on local demands of the occupants to strike a balance between infection risk and energy saving. In this work, a zonal demand-controlled ventilation (ZDCV) strategy was proposed to optimize the ventilation rates in sub-zones. A camera-based occupant detection method was developed to detect occupants (with eight possible locations in sub-zones denoted as 'A' to 'H'). Linear ventilation model (LVM), dimension reduction, and artificial neural network (ANN) were integrated for rapid prediction of pollutant concentrations in sub-zones with the identified occupants and ventilation rates as inputs. Coordinated ventilation effects between sub-zones were optimized to improve infection prevention and energy savings. Results showed that rapid prediction models achieved an average prediction error of 6 ppm for CO2 concentration fields compared with the simulation under different occupant scenarios (i.e., occupant locations at ABH, ABCFH, and ABCDEFH). ZDCV largely reduced the infection risk to 2.8% while improved energy-saving efficiency by 34% compared with the system using constant ventilation rate. This work can contribute to the development of building environmental control systems in terms of pollutant removal, infection prevention, and energy sustainability.

Effects of pressure-controlled ventilation targeting end-inspiratory flow rate on pulmonary complications and inflammation levels in patients undergoing spinal surgery in the prone position: a randomized clinical trial.

BACKGROUND: This study assessed the impact of pressure-controlled ventilation (PCV) focusing on end-inspiratory flow rate on the incidence of postoperative pulmonary complications (PPCs) and inflammation levels in patients undergoing spinal surgery in the prone position. METHODS: A total of 187 patients who underwent posterior spinal surgery were enrolled and randomly divided into 3 groups: 61 in the volume-controlled ventilation (VCV) group (group V), 62 in the PCV-volume-guaranteed (VG) group (group P1), and 64 in the PCV-VG end-expiratory zero flow rate group (group P2). Indicators including tidal volume (VT), peak airway pressure (Ppeak), and dynamic lung compliance (Cdyn) were recorded. The Ppeak, Cdyn, PETCO2, and oxygenation index (PaO2/FiO2) after intubation (T0), after prone position (T1), 60 min after prone position (T2), and after supine position at the end of surgery (T3) of the three groups were collected. RESULTS: In the within-group comparison, compared with T0, Ppeak increased at T1 - 2 in groups V and P1 (P < 0.01), whereas it decreased at T1 - 3 in group P2 (P < 0.01). Cdyn decreased at T1 - 2 and PaO2/FiO2 increased at T1 - 3 in all three groups (P < 0.01), and PaO2/FiO2 increased at T1 - 3 (P < 0.01). Compared with group V, Ppeak decreased at T0 - 3 in group P1 (P < 0.01) and at T1 - 3 in group P2 (P < 0.01), while Cdyn increased at T0 - 3 in groups P1 and P2 (P < 0.01). Compared with group P1, Ppeak was elevated at T0 (P < 0.01) and decreased at T1 - 3 (P < 0.05), and Cdyn was elevated at T0 - 3 in group P2 (P < 0.01). The total incidence of PPCs in group P2 was lower than that in group V (P < 0.01). Compared with the preoperative period, serum interleukin 6 (IL-6) and C-reactive protein (CRP) levels were increased at 24 and 72 h after surgery in group V (P < 0.01), whereas that was increased at 24 h after surgery in group P1 and group P2 (P < 0.01). Compared with group V, serum IL-6 and CRP levels were reduced at 24 h after surgery in groups P1 and P2 (P < 0.01 or < 0.05). CONCLUSION: In patients undergoing spinal surgery in the prone position, PCV-VG targeting an end-inspiratory zero flow rate lowers the incidence of PPCs and inflammation levels.

Comparative study of ventilation techniques with supraglottic airway devices in cats: volume-controlled vs pressure-controlled techniques.

OBJECTIVES: This study compared the effectiveness of a new supraglottic airway device (SGAD) in cats undergoing anaesthesia using two types of mechanical ventilation: volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV). METHODS: A total of 13 healthy cats (five male, eight female; median age 2 years [range 1-3]) were randomly allocated to either VCV or PCV. Five tidal volumes (6, 8, 10, 12 and 14 ml/kg) and five peak inspiratory pressures (4, 5, 6, 7 and 8 cmH2O) were randomly applied with a minute ventilation of 100 ml/kg/min. Various parameters, such as blood pressure, gas leakage, end-tidal CO2 (ETCO2) and work of breathing (WOB), were measured while using VCV or PCV. RESULTS: The occurrence of hypotension (mean arterial blood pressure <60 mmHg) was slightly less frequent with VCV (38 events, 65 ventilating sessions) than with PCV (40 events, 65 ventilating sessions), but this difference did not reach statistical significance (P = 0.429). The number of leakages did not differ between the VCV group (3 events, 65 ventilating sessions) and the PCV group (3 events, 65 ventilating sessions) (P = 1.000). Hypercapnia was identified when using VCV (10 events, 65 ventilating sessions) less frequently than when using PCV (17 events, 65 ventilating sessions), but this difference did not reach statistical significance (P = 0.194). The study found a significantly higher WOB in the PCV group compared with the VCV group (P <0.034). CONCLUSIONS AND RELEVANCE: The present results suggested that both VCV and PCV can be used with an SGAD during anaesthesia, with VCV preferred for prolonged mechanical ventilation due to its lower workload. Adjusting tidal volume or inspiratory pressure corrects hypercapnia.

Accuracy of tidal volume delivery by paediatric intensive care ventilators: A bench-model study.

BACKGROUND: Tidal volume (Vt) delivery during mechanical ventilation is influenced by gas compression, humidity, and temperature. OBJECTIVES: This bench study aimed at assessing the accuracy of Vt delivery by paediatric intensive care ventilators according to the humidification system. Secondary objectives were to assess the following: (i) the accuracy of Vt delivery in ventilators with an integrated Y-piece pneumotachograph and (ii) the ability of ventilators to deliver and maintain a preset positive end-expiratory pressure. METHODS: Six latest-generation intensive care ventilators equipped with a paediatric mode were tested on the ASL5000 test lung in four simulated paediatric bench models (full-term neonate, infant, preschool-age chile, and school-age child), under volume-controlled mode with a heated humidifier (HH) or a heat moisture exchanger, with various loading conditions. Three ventilators equipped with a Y-piece pneumotachograph were tested with or without the pneumotachograph in the neonatal and infant models. "Accurate Vt" delivery was defined as a volume error (percentage of the preset Vt under body temperature and pressure and saturated water vapour conditions) being ≤10 % of the absolute preset value. RESULTS: Vt accuracy varied significantly across ventilators but was acceptable in almost all the ventilators and all the models, except the neonatal model. The humidification system had an impact on Vt delivery in the majority of the tested conditions (p < 0.05). The use of an HH was associated with a better Vt accuracy in four ventilators (V500, V800, R860, and ServoU) and allowed to achieve an acceptable level of volume error in the neonatal model as compared to the use of heat moisture exchanger. The use of an integrated pneumotachograph was associated with lower volume error in only one ventilator (p < 0.01). All the tested ventilators were able to maintain adequate positive end-expiratory pressure levels. CONCLUSION: The humidification system affects Vt accuracy of paediatric intensive care ventilators, especially in the youngest patients for whom the HH should be preferred.

Simulated ventilation of two patients with a single ventilator in a pandemic setting.

Simultaneous ventilation of two patients may lead to hypoventilation in one patient and hyperinflation in the other patient. In a simulation of ventilation in two patients using artificial lungs, we voluntarily directed gas flow to one patient by using three-dimensional-printed Y-adapters and stenosis adapters during volume- and pressure-controlled ventilation in the first set up. We continuously modified the model using a special one-way valve on the flow-limited side and measured it in pressure-controlled ventilation with the flow sensor of the ventilator adjusted on both sides in a second and third setup. In the first setup, volume- or pressure-controlled ventilation resulted in comparable minute volumes in both lungs, even when one side was obstructed to 3 mm. In the second setup, with a 3-mm flow limitation, we had a minute ventilation of 9.4 ± 0.3 vs. 3.5 ± 0.1 L/min. In the third setup, ventilation with a 3-mm flow limitation resulted in minute ventilation of 7.2 ± 0.2 vs. 5.70 L/min at a compliance of 30 vs. 70 mL/mbar. It is possible to override the safety features of a modern intensive care ventilator and thus direct tidal volumes in different lung conditions to one lung using three-dimensional-printed flow limiters. While this ventilation setting was technically feasible in a bench model, it would be unstable, if not dangerous, in a clinical situation.

Effect of Mechanical Ventilation Mode Type on Postoperative Pulmonary Complications After Cardiac Surgery: A Randomized Controlled Trial.

OBJECTIVES: It is unknown whether there is a difference in pulmonary outcome in different intraoperative ventilation modes for cardiac surgery with cardiopulmonary bypass (CPB). The aim of this trial was to determine whether patients undergoing cardiac surgery with CPB could benefit from intraoperative optimal ventilation mode. DESIGN: This was a single-center, prospective, randomized controlled trial. SETTING: The study was conducted at a single-center tertiary-care hospital. PARTICIPANTS: A total of 1,364 adults undergoing cardiac surgery with CPB participated in this trial. INTERVENTIONS: Patients were assigned randomly (1:1:1) to receive 1 of 3 ventilation modes: volume-controlled ventilation (VCV), pressure-controlled ventilation (PCV), and pressure-controlled ventilation-volume guaranteed (PCV-VG). All arms of the study received the lung-protective ventilation strategy. MEASUREMENTS AND MAIN RESULTS: The primary outcome was a composite of postoperative pulmonary complications (PPCs) within the first 7 postoperative days. Pulmonary complications occurred in 168 of 455 patients (36.9%) in the PCV-VG group, 171 (37.6%) in the PCV group, and 182 (40.1%) in the VCV group, respectively. There was no statistical difference in the risk of overall pulmonary complications among groups (p = 0.585). There were no significant differences in the severity grade of PPCs within 7 days, postoperative ventilation duration, intensive care unit stay, postoperative hospital stay, or 30-day postoperative mortality. CONCLUSIONS: Among patients scheduled for cardiac surgery with CPB, intraoperative ventilation mode type did not affect the risk of postoperative pulmonary complications.

Pressure-controlled ventilation-volume guaranteed mode improves bronchial mucus transport velocity in patients during laparoscopic surgery for gynecological oncology: a randomized controlled study.

BACKGROUND: Mechanical ventilation during general anesthesia may impair airway mucosal function. This study aimed to investigate the effect of pressure-controlled ventilation-volume guaranteed (PCV-VG) on bronchial mucus transport velocity (BTV) in patients during laparoscopic surgery for gynecological oncology compared with volume controlled ventilation (VCV). METHODS: 66 patients undergoing elective a laparoscopic surgery for gynecological oncology. The patients were randomized into two group receiving either PCV-VG or VCV. a drop of methylene blue was placed on the surface of the airway mucosa under the bronchoscopeand, then the distance the dye movement was measured after 2, 4, and 6 min. Outcomes were assessed at T0 (5 min after endotracheal intubation and before initiation of pneumoperitoneum), T1 and T2 (1 and 2 h after stabilization of pneumoperitoneum respectively). BTV at T0, T1 and T2 was the primary outcome. Secondary outcomes included heart rate (HR), mean arterial pressure (MAP), body temperature, end-tidal CO2 pressure (PETCO2), tidal volume(VT), peak inspiratory pressure (PIP), mean inspiratory pressure (Pmean), respiratory rate (RR), and dynamic compliance (CDyn) at T0, T1, and T2. RESULTS: 64 patients were included in the analysis. The median [interquartile range] BTV was significantly lower in VCV group at T1 and T2 that at T0 (P < 0.05). Furthermore, BTV was slightly reduced in PCV-VG compared with VCV. BTV in PCV-VG was significantly decreased at T2 compared with BTV at T0 (P < 0.05) and slightly decreased at T1 compared with T0(P > 0.05). Compared with the PCV-VG group, BTV in VCV group significantly decreased at T2 (P < 0.05). No participants experienced respiratory complications. CONCLUSIONS: PCV-VG is more suitable for patients undergoing laparoscopic surgery for gynecological oncology than VCV since it can protect mucociliary clearance function. TRIAL REGISTRATION: This trial is registered on https://www.chictr.org.cn/ in Chinese Clinical Trial Registry (ChiCTR.2200064564: Date of registration 11/10/2022).

Airway management during unusual tracheal stenosis: A clinical feasibility trial.

Objectives: Prolonged intubation is a known risk factor of LTS. LTS related to COVID-19 may result in a different phenotype: pronation affects the location of stenosis and COVID-19 pneumonia can decline lung mechanics. Therefore, airway management in these patients may carry unique challenges for both anesthesiologists and surgeons.This prospective observational feasibility trial aims to evaluate the use of a novel thin, cuffed, endotracheal tube (Tritube) in combination with flow-controlled ventilation (FCV) in the management of patients with COVID-19-related LTS undergoing laryngeal surgery. Methods: 20 patients suffering from COVID-19-related LTS, as diagnosed by CT, requiring endolaryngeal surgery, with or without CO2 laser, were included. Ultrathin endotracheal tube Tritube, together with FCV was used for airway management and ventilation. Feasibility, ventilation efficiency, and surgical exposure were evaluated. Results: Median duration of mechanical ventilation during their ICU stay was 17 days, (range, 7-27), and all patients had been pronated. In 18/20 patients, endoscopic diagnosis confirmed the initial CT diagnosis: posterior subglottic stenosis. Surgeons' satisfaction on the view was rated 9 out of 10 (range 7-10), where 0 was the worst view and 10 was the best view. Hemodynamic and respiratory variables were within the normal clinical range during the surgical procedure. One patient that had a SpO2 of 90% before induction of anesthesia, a temporal drop to 89%, caused meeting the predefined requirement of "respiratory complication." Conclusion: This study demonstrates the feasibility of using Tritube with FCV in patients with relatively unusual subglottic posterior location tracheal stenosis, undergoing laryngotracheal surgery. Tritube provides a good surgical field and FCV provides highly adequate ventilation especially in patients with compromised lung mechanics. Level of Evidence: IV, non-comparitive prospective clinical trial with 20 patients.

Flow-controlled versus pressure-controlled ventilation in cardiac surgery with cardiopulmonary bypass - A single-center, prospective, randomized, controlled trial.

STUDY OBJECTIVE: Multifactorial comparison of flow-controlled ventilation (FCV) to standard of pressure-controlled ventilation (PCV) in terms of oxygenation in cardiac surgery patients after chest closure. DESIGN: Prospective, non-blinded, randomized, controlled trial. SETTING: Operating theatre at an university hospital, Austria. PATIENTS: Patients scheduled for elective, open, on-pump, cardiac surgery. INTERVENTIONS: Participants were randomized to either individualized FCV (compliance guided end-expiratory and peak pressure setting) or control of PCV (compliance guided end-expiratory pressure setting and tidal volume of 6-8 ml/kg) for the duration of surgery. MEASUREMENTS: The primary outcome measure was oxygenation (PaO2/FiO2) 15 min after intraoperative chest closure. Secondary endpoints included CO2-removal assessed as required minute volume to achieve normocapnia and lung tissue aeration assessed by Hounsfield unit distribution in postoperative computed tomography scans. MAIN RESULTS: Between April 2020 and April 2021 56 patients were enrolled and 50 included in the primary analysis (mean age 70 years, 38 (76%) men). Oxygenation, assessed by PaO2/FiO2, was significantly higher in the FCV group (n = 24) compared to the control group (PCV, n = 26) (356 vs. 309, median difference (MD) 46 (95% CI 3 to 90) mmHg; p = 0.038). Additionally, the minute volume required to obtain normocapnia was significantly lower in the FCV group (4.0 vs. 6.1, MD -2.0 (95% CI -2.5 to -1.5) l/min; p < 0.001) and correlated with a significantly lower exposure to mechanical power (5.1 vs. 9.8, MD -5.1 (95% CI -6.2 to -4.0) J/min; p < 0.001). Evaluation of lung tissue aeration revealed a significantly reduced amount of non-aerated lung tissue in FCV compared to PCV (5 vs. 7, MD -3 (95% CI -4 to -1) %; p < 0.001). CONCLUSIONS: In patients undergoing on-pump, cardiac surgery individualized FCV significantly improved oxygenation and lung tissue aeration compared to PCV. In addition, carbon dioxide removal was accomplished at a lower minute volume leading to reduced applied mechanical power.

Evaluation of the Effect of Pressure-Controlled Ventilation-Volume Guaranteed Mode vs. Volume-Controlled Ventilation Mode on Atelectasis in Patients Undergoing Laparoscopic Surgery: A Randomized Controlled Clinical Trial.

Background and Objectives: Laparoscopic surgery, which results in less bleeding, less postoperative pain, and better cosmetic results, may affect the lung dynamics via the pneumoperitoneum. After laparoscopic surgery, atelectasis develops. The primary aim of the present study is to demonstrate the effects of two different ventilation modes on the development of atelectasis using lung ultrasound, and the secondary outcomes include the plateau pressure, peak inspiratory pressure, and compliance differences between the groups. Materials and Methods: In this study, 62 participants aged 18-75 years undergoing laparoscopic cholecystectomy were enrolled. The patients were randomly assigned into two groups: the volume-controlled ventilation (VCV) group (group V) or the pressure-controlled-volume guaranteed ventilation (PCV-VG) group (group PV). The lung ultrasound score (LUS) was obtained thrice: prior to induction (T1), upon the patient's initial arrival in the recovery room (T2), and just before departing the recovery unit (T3). The hemodynamic data and mechanical ventilation parameters were recorded at different times intraoperatively. Results: The LUS score was similar between the groups at all the times. The change in the LUS score of the right lower anterior chest was statistically higher in the VCV group than the PCV group. The peak inspiratory pressure (PIP) was found to be statistically higher in the V group than the PV group five minutes after induction (T5) (20.84 ± 4.32 p = 0.021). The plateau pressure was found to be higher in the V group than the PV group at all times (after induction (Tind) 17.29 ± 5.53 p = 0.004, (T5) 17.77 ± 4.89 p = 0.001, after pneumoperitoneum (TPP) 19.71 ± 4.28 p = 0.002). Compliance was found to be statistically higher in the PV group than the V group at all times ((Tind) 48.87 ± 15.37 p = 0.011, (T5) 47.94 ± 13.71 p = 0.043, (TPP) 35.65 ± 6.90 p = 0.004). Before and after the pneumoperitoneum, the compliance was determined to be lower in the V group than the PV group, respectively (40.68 ± 13.91 p = 0.043, 30.77 ± 5.73 p = 0.004). Conclusions: LUS score was similar between groups at all times. The PCV-VG mode was superior to the VCV mode in providing optimal ventilatory pressures and maintaining high dynamic compliance in patients undergoing laparoscopic abdominal surgery.

A survey of preferences for respiratory support in the intensive care unit for patients with acute hypoxaemic respiratory failure.

BACKGROUND: When caring for mechanically ventilated adults with acute hypoxaemic respiratory failure (AHRF), clinicians are faced with an uncertain choice between ventilator modes allowing for spontaneous breaths or ventilation fully controlled by the ventilator. The preferences of clinicians managing such patients, and what motivates their choice of ventilator mode, are largely unknown. To better understand how clinicians' preferences may impact the choice of ventilatory support for patients with AHRF, we issued a survey to an international network of intensive care unit (ICU) researchers. METHODS: We distributed an online survey with 32 broadly similar and interlinked questions on how clinicians prioritise spontaneous or controlled ventilation in invasively ventilated patients with AHRF of different severity, and which factors determine their choice. RESULTS: The survey was distributed to 1337 recipients in 12 countries. Of these, 415 (31%) completed the survey either fully (52%) or partially (48%). Most respondents were identified as medical specialists (87%) or physicians in training (11%). Modes allowing for spontaneous ventilation were considered preferable in mild AHRF, with controlled ventilation considered as progressively more important in moderate and severe AHRF. Among respondents there was strong support (90%) for a randomised clinical trial comparing spontaneous with controlled ventilation in patients with moderate AHRF. CONCLUSIONS: The responses from this international survey suggest that there is clinical equipoise for the preferred ventilator mode in patients with AHRF of moderate severity. We found strong support for a randomised trial comparing modes of ventilation in patients with moderate AHRF.

Clinical evaluation of ventilation mode on acute exacerbation of chronic obstructive pulmonary disease with respiratory failure.

BACKGROUND: At present, understanding of the most effective ventilation methods for treating chronic obstructive pulmonary disease (COPD) patients experiencing acute worsening symptoms and respiratory failure remains relatively limited. This report analyzed the efficiency and side effects of various ventilation techniques used for individuals experiencing an acute COPD exacerbation. AIM: To determine whether pressure-controlled ventilation (PCV) can lower peak airway pressures (PAPs) and reduce the incidence of barotrauma compared to volume-controlled ventilation (VCV), without compromising clinical outcomes and oxygenation parameters. METHODS: We have evaluated 600 patients who were hospitalized due to a severe COPD exacerbation, with 400 receiving mechanical ventilation for the respiratory failure. The participants were divided into two different groups, who were administered either VCV or PCV, along with appropriate management. We thereafter observed patients' attributes, clinical factors, and laboratory, radiographic, and arterial blood gas evaluations at the start and during their stay in the intensive care unit (ICU). We have also employed appropriate statistical methods for the data analysis. RESULTS: Both the VCV and PCV groups experienced significant enhancements in the respiratory rate, tidal volume, and arterial blood gas values during their time in the ICU. However, no significant distinctions were detected between the groups in terms of oxygenation indices (partial pressures of oxygen/raction of inspired oxygen ratio) and partial pressures of carbon dioxide improvements. There was no considerable disparity observed between the VCV and PCV groups in the hospital mortality (32% vs 28%, P = 0.53), the number of days of ICU stay [median interquartile range (IQR): 9 (6-14) d vs 8 (5-13) d, P = 0.41], or the duration of the mechanical ventilation [median (IQR): 6 (4-10) d vs 5 (3-9) d, P = 0.47]. The PCV group displayed lower PAPs compared to the VCV group (P < 0.05) from the beginning of mechanical ventilation until extubation or ICU departure. The occurrence of barotrauma was considerably lower in the PCV group in comparison to the VCV group (6% vs 16%, P = 0.03). CONCLUSION: Both VCV and PCV were found to be effective in treating patients with acute COPD exacerbation. However, PCV was associated with lower PAPs and a significant decrease in barotrauma, thus indicating that it might be a safer ventilation method for this group of patients. However, further large-scale study is necessary to confirm these findings and to identify the best ventilation approach for patients experiencing an acute COPD exacerbation.

Ventilación controlada por flujo y gafas nasales de alto flujo en cirugía láser de estenosis subglótica grado III / Flow-controlled ventilation and hi-flow nasal oxygen in laser surgery for a grade III subglottic stenosis patient

Paciente de 49 años (IMC 29,4 kg/m2 y ASA III) con estenosis subglótica (ES) de más de 70% (grado III) intervenida mediante resección láser y posterior dilatación. Durante la resección láser se empleó ventilación controlada por flujo utilizando el respirador Evone®, que permite controlar todo el ciclo respiratorio regulando tanto el flujo inspiratorio como el espiratorio sin comprometer el intercambio gaseoso a pesar de administrar FIO2 máxima de 0,3 por riesgo de ignición. Antes de proceder a la dilatación endoscópica, se retiró el tubo endotraqueal láser de 4,5 mm de diámetro interno y se inició terapia con gafas nasales de alto flujo (GNAF) para prolongar la oxigenación apneica. El tiempo total de apnea fue de 11 minutos, manteniendo en todo momento SpO2 > 98% y End Tidal de CO2 máximo de 60 mmHg.(AU)

A 49-year old patient (BMI 29.4 kg/m2 and ASA III) with grade III subglottic stenosis (> ventilator in flow controlled ventilation mode, which allowed us to regulate both inspiratory and expiratory flow without compromising gas exchange despite maintaining peak FIO2 at 0.3 due to the risk of ignition. Before proceeding with endoscopic dilation, the 4.5 mm laser endotracheal tube was withdrawn and high flow nasal cannula oxygenation was started in order to prolong apnoeic oxygenation. Total apnoea time was 11 minutes, maintaining SpO2 > 70%) underwent laser resection followed by dilation. During resection he was ventilated by the Evone > ventilator; high flow nasal cannula therapy; apnoeic oxygenation-98% and peak EtCO2 60 mmHg throughout the procedure.(AU)