Volume-controlled Mode Research Articles

Abstract Sa1107: Resuscitation of Lungs after Cardiac Arrest with Ex-Vivo Lung Perfusion: A Bench Study to Minimize Ventilator-Induced Lung Injury through Flow Modulation

Introduction: Lung donation after uncontrolled circulatory death (uDCD) following a witnessed cardiac arrest is feasible after resuscitation and assessment with ex vivo lung perfusion (EVLP). This bench study explores the efficacy of expiratory flow modulation in minimizing damage caused by mechanical power during volume-controlled ventilation within the EVLP procedure. Methods: Donor lungs were simulated using the ASL 5000 lung simulator (IngMar Medical) and ventilated in volume-controlled mode using the ViX-ventilator (KU Leuven), set at 7 breaths per minute with a positive end-expiratory pressure of 5 cmH 2 O. (Figure 1) Baseline measurements were obtained to deliver tidal volumes (VT) of 300, 400, and 500 mL. These measurements were then compared to an intervention where expiratory flow was modulated using an in-house designed device, the flow modulator. Mechanical power (J/min) was calculated using the pressure-volume curve. Differences in power between the baseline and various levels of flow modulation were assessed using a one-sided t-test. Results: No clinically relevant differences were observed in VT delivery between baseline settings and during expiratory flow modulation. (Table 1) However, significant differences in mechanical power were noted between baseline and flow modulation across the three VT settings (p<0.001). The reduction in power varied from 10.9% to 58.5%, depending on the selected VT and the degree of flow modulation applied. Notably, the extent of power reduction increased with the level of flow modulation. Conclusion: Flow modulation in the expiratory circuit during volume-controlled ventilation in a bench set-up does not affect VT delivery and can significantly reduce mechanical power by up to 58.5%. This reduction in mechanical power could potentially reduce iatrogenic damage during EVLP. Consequently, this might extend preservation times and improve the resuscitation outcomes of uncontrolled DCD lungs. Emergency medicine has the opportunity to leverage this vital pool of donor lungs, moving towards a future with minimal transplant waitlists.

Performance of newly developed add-on devices on aerosol delivery in noninvasive ventilated subjects

Background: Several techniques had been developed to generate aerosolized medications during noninvasive ventilation (NIV) using variable inhalation methods. This study hypothesized that large spacers were more efficient significantly than small spacers and adapters during NIV. Objective: The main objective of this study was to compare the performance of newly developed spacers with standard T-piece in NIV chronic obstructive pulmonary disease (COPD) subjects. Methods: Sixty COPD subjects requiring NIV were included in this study. A dual-limb circuit was used, and the mode of ventilator was set in spontaneous volume-controlled mode. Dual-limb ventilation circuit, consists of inspiratory-limb and expiratory-limb, is pressure and volume controlled in response to subject expiration providing relatively high resistance to expiratory flow. Two experimental sets were evaluated: the first was introducing two preliminary pressurized metered-dose inhalers (pMDI) puffs before the nebulization of 1 ml of a respirable solution of salbutamol by vibrating mesh nebulizer (VMN) using Minimhal and Combihaler. The second was to only nebulize 1 ml of salbutamol respirable solution by VMN using Combihaler, Minimhal, and standard T-piece. Two urine samples were collected after aerosol delivery: urine sample after 30 min. (USAL0.5) as an indicator of lung deposition and all urine pooled 24 h (USAL24) post-inhalation as an indicator of systemic absorption. The amount of salbutamol extracted from urine samples was assayed by high-performance liquid chromatography. Results: Minimhal + pMDI + VMN delivered a higher percentage of salbutamol 30 min post-inhalation than Minimhal + VMN (p < 0.001). Also, Combihaler + pMDI + VMN delivered a higher percentage of salbutamol 30 min post-inhalation than Combihaler + VMN (p < 0.001). Combihaler + VMN delivered a higher percentage of salbutamol 30 min and 24 h post-inhalation than both Minimhal + VMN and T-piece + VMN (p < 0.001). Standard T-piece delivered the lowest aerosol amount delivered to the lung compared to both spacers (p < 0.05). Conclusions: Introducing two pMDI puffs significantly improved aerosol delivery by both spacers. Combihaler significantly improves aerosol delivery more than Minimhal.

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

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

Management of adult mechanically ventilated patients: A UK-wide survey.

Mechanical ventilation is a common and often lifesaving intervention that is utilised in intensive care. However, the practices can vary between centres. Through this national survey we aim to gain more information about different strategies adopted across the UK. All adult intensive care units in the UK were approached to participate. The questionnaire was developed with an electronic survey engine and conducted between 09/11/2023 and 01/04/2024 (Survey Monkey®). The survey included questions on ventilator modes, settings, protocols/pathways, rescue strategies, immediate post-extubation period and follow-up. There were 196 responses from 104 hospitals. The most widely adopted start-up ventilation mode was pressure-regulated volume-controlled mode. For acute hypoxaemic respiratory failure (AHRF), most of respondents reported full (39.8%) or partial compliance (58.1%) with the ARDSnet protocol, with PEEP settings being the commonest deviation. Prone positioning (99.0%), followed by recruitment manoeuvres (91.3%) were commonly used rescue measures during AHRF. APRV (55.7%), inhaled (51.3%) and systemic pulmonary vasodilators (44.1%) were also commonly used. Conservative oxygen targets (SaO2 of 88%-92%) were commonly adopted (70.6%). As a care bundle, intermittent ETT cuff pressure monitoring was more common (65.5%) than continuous cuff pressure monitoring (20.0%). Propofol and alfentanil were the most common initial sedative and analgesia (99.5% and 56.9%) respectively. Routine volatile anaesthetic use was rare. Our survey has shown significant variation of practice in common but crucial elements of management of patients receiving mechanical ventilation. We hope the results in our survey highlight potential future areas of research. South-coast Peri-operative Audit and Research Collaborative (SPARC)Severn Trainee Anaesthetic and Critical Care Research group (STAR)Collaborative research in Anaesthesia in the Northeast (CRANE).

Correlation analysis of central venous pressure and Intra-thoracic pressures in Acute Respiratory Distress Syndrome mechanical ventilated patients, a pilot Study

Abstract Background Positive end expiratory pressure can affect measurement of central venous pressure through increased intrathoracic pressure. However, when positive end expiratory pressure (PEEP) is applied, central venous pressure and pleural pressure often increases more than right atrial pressure, so that transmural right atrial pressure (true filling pressure) decreases. Aim of the study Primary end point was to recognizing correlation coefficient between mean CVP and intra- thoracic pressures on volume-controlled mode and spontaneous modes on same population of mechanically ventilated ARDS patients. The secondary end point is to compare the correlation coefficient R during both modes with parameters of ventilatory settings. Patient and Methods A cohort observational prospective study was done enrolling single group of patients with acute respiratory distress syndrome, who necessitate mechanical ventilation more than two days after connection to ventilators, the study was performed with demonstration of central venous pressure in cmH2O upon application of needed PEEP. Central venous catheter inserted for measuring CVP were processed in accordance with the standard guidelines. Results There were statistically significant differences between control and support group regarding the PEEP, Plateau pressure, mean CVP and mean airway pressure MAP. The data were higher in control than support group with p-value &amp;lt;0.001, 0.002 and 0.004, respectively. There was statistically significant positive correlation between R and CVP in the control group with p &amp;lt; 0.001 and r = 0.918. There was statistically significant positive correlation between R and ΔPIT in support group with p 0.001 and r = 0.926. The correlation between CVP and R among the control group was R = 0.028 + 0.032 * CVP with p-value &amp;lt;0.001, whereas the correlation between ΔPIT and R among the support group was R = 0.465 + 0.020 * ΔPIT with p-value = 0.022 Conclusion The relation between hemodynamics change of central venous pressures and intrathoracic pressure is new independent marker for evaluating ARDS mechanically ventilated patients. Values of R correlation are different in controlled mode relative to spontaneous mode during ARDS ventilated patients.

Comparison of Volume-Controlled Ventilation (VCV) Mode and Pressure-Controlled Ventilation (PCV) Mode in Patients Undergoing Lumbar Spine Surgery in the Prone Position

Abstract Background The prone position is commonly required to enable surgical access during lumbar spine surgery. When a patient moves into the prone position, inferior vena cava obstruction causes reduced venous return and increase thoracic pressure results in reduced left ventricular compliance, leading to a decreased cardiac index (CI). Aim of the Work The aim of this study, we will compare the effects of the VCV and PCV on peak airway pressure (P peak), ETCO2 as a primary outcome ABG, SPO2, and hemodynamics as MAP, HR and as a secondary outcome in the prone position. Patients and Methods This prospective, single blinded study included 60 patients who assigned randomly into two equal groups: group A: patients on volume-controlled ventilation mode VCV and group B: patients on pressure-controlled ventilation mode PCV. Results Baseline characteristics (age, sex, BMI, ASA physical status, duration of anesthesia and surgery) were insignificantly different between both groups. Heart rate and MAP at supine and prone positions at all time measurements were insignificantly different between both groups. P peak and SpO2 at supine and prone positions at all time measurements were insignificantly different between both groups. Respiratory rate and ETCO2 at supine and prone positions at all time measurements were insignificantly different between both groups. Conclusion No significant difference between two modes of ventilation VCV and PCV in patients undergoing lumbar spine surgery in the prone position as regard P peak, ETCO2, SPO2, and hemodynamics.

Association between mechanical power during one-lung ventilation and pulmonary complications after thoracoscopic lung resection surgery: a prospective observational study

BackgroundThe role of mechanical power on pulmonary outcomes after thoracic surgery with one-lung ventilation was unclear. We investigated the association between mechanical power and postoperative pulmonary complications in patients undergoing thoracoscopic lung resection surgery.MethodsIn this single-center, prospective observational study, 622 patients scheduled for thoracoscopic lung resection surgery were included. Volume control mode with lung protective ventilation strategies were implemented in all participants. The primary endpoint was a composite of postoperative pulmonary complications during hospital stay. Multivariable logistic regression models were used to evaluate the association between mechanical power and outcomes.ResultsThe incidence of pulmonary complications after surgery during hospital stay was 24.6% (150 of 609 patients). The multivariable analysis showed that there was no link between mechanical power and postoperative pulmonary complications.ConclusionsIn patients undergoing thoracoscopic lung resection with standardized lung-protective ventilation, no association was found between mechanical power and postoperative pulmonary complications.Trial registrationTrial registration number: ChiCTR2200058528, date of registration: April 10, 2022.

External Jet Nebulization and Measured Ventilator Performance.

During invasive ventilation, external flow jet nebulization results in increases in displayed exhaled tidal volumes (VT). We hypothesized that the magnitude of the increase is inaccurate. An ASL 5000 simulator measured ventilatory parameters over a wide range of adult settings: actual VT, peak inspiratory pressure (PIP), and time to minimum pressure. Ventilators with internal and external flow sensors were tested by using a variety of volume and pressure control modes (the target VT was 420 mL). Patient conditions (normal, COPD, ARDS) defined on the ASL 5000 were assessed at baseline and with 3.5 or 8 L/min of added external flow. Patient-triggering was assessed by reducing muscle effort to the level that resulted in backup ventilation and by changing ventilator sensitivity to the point of auto-triggering. Results are reported as percentage change from baseline after addition of 3.5 or 8 L/min external flow. For ventilators with internal flow sensors, changes in displayed exhaled VT ranged from 10% to 118%, however, when using volume control, actual increases in actual VT and PIP were only 4%-21% (P = .063, .031) and 6%-24% (P = .25, .031), respectively. Changes in actual VT correlated closely with changes in PIP (P < .001; R2 = 0.68). For pressure control, actual VT decreased by 3%-5% (P = .031) and 4%-9% (P = .031) with 3.5 and 8 L/min respectively, PIP was unchanged. With external flow sensors at the distal Y-piece junction, volume and pressure changes were statistically insignificant. The time to minimum pressure increased at most by 8% (P = .02) across all modes and ventilators. The effects on muscle pressure were minimal (∼1 cm H2O), and ventilator sensitivity effects were nearly undetectable. External flow jet nebulization resulted in much smaller changes in volume than indicated by the ventilator display. Statistically significant effects were confined primarily to machines with internal flow sensors. Differences approached the manufacturer-reported variation in ventilator baseline performance. During nebulizer therapy, effects on VT can be estimated at the bedside by monitoring PIP.

A non-invasive method to monitor respiratory muscle effort during mechanical ventilation.

This study introduces a method to non-invasively and automatically quantify respiratory muscle effort (Pmus) during mechanical ventilation (MV). The methodology hinges on numerically solving the respiratory system's equation of motion, utilizing measurements of airway pressure (Paw) and airflow (Faw). To evaluate the technique's effectiveness, Pmus was correlated with expected physiological responses. In volume-control (VC) mode, where tidal volume (VT) is pre-determined, Pmus is expected to be linked to Paw fluctuations. In contrast, during pressure-control (PC) mode, where Paw is held constant, Pmus should correlate with VT variations. The study utilized data from 250 patients on invasive MV. The data included detailed recordings of Paw and Faw, sampled at 31.25Hz and saved in 131.1-second epochs, each covering 34 to 41 breaths. The algorithm identified 51,268 epochs containing breaths on either VC or PC mode exclusively. In these epochs, Pmus and its pressure-time product (PmusPTP) were computed and correlated with Paw's pressure-time product (PawPTP) and VT, respectively. There was a strong correlation of PmusPTP with PawPTP in VC mode (R² = 0.91 [0.76, 0.96]; n = 17,648 epochs) and with VT in PC mode (R² = 0.88 [0.74, 0.94]; n = 33,620 epochs), confirming the hypothesis. As expected, negligible correlations were observed between PmusPTP and VT in VC mode (R² = 0.03) and between PmusPTP and PawPTP in PC mode (R² = 0.06). The study supports the feasibility of assessing respiratory effort during MV non-invasively through airway signal analysis. Further research is warranted to validate this method and investigate its clinical applications.

Clinical characteristics, complications and in-hospital mortality in patients in the coronary care unit requiring invasive mechanical ventilation

Abstract Funding Acknowledgements None. Introduction Mechanical ventilation (MV) is one of the most widely used life support techniques in critically ill patients and, due to the increasing number of coronary care units (CCU), adequate management of this technique is essential. Purpose The aim of our study was to describe the profile of patients requiring invasive MV (IMV) in our CCU, as well as the mode of ventilation, complications and in-hospital mortality. Methods Single-center retrospective observational study of a cohort of patients admitted to a CCU between January 2018 and March 2023 who required IMV. Baseline characteristics, reason for admission and intubation, as well as evolution and complications during admission were analyzed. Results A total of 157 patients were included, 113 (72%) men. The mean age was 66.9 years (SD 12.2). Table 1 summarizes the history and baseline characteristics of the patients. Image 1 summarizes the reasons for admission. Regarding the causes of oro-tracheal intubation, the most frequent was cardiopulmonary arrest (CPA) (49.7%), followed by respiratory failure (32.5%) and cardiogenic shock (CS) (16.6%). Regarding left ventricular ejection fraction (LVEF) on admission, 69.4% had LVEF&amp;lt;52%, with 32.5% of all patients having LVEF below 30%. The most used ventilation mode as initial mode was volume-controlled mode (VC/AC), used in 71.3% of patients. The mean stay in CCU was 11 (min 1-max 78, SD 12) and of orotracheal intubation was 5 days (min 1-max 64, SD 7). Mean days to weaning from VMI was 2 (min 0-max 8, SD 2). Failure on extubation occurred in 38 patients (19.1%), the most frequent reasons being need for reintubation (12.7%), need for noninvasive MV (8.9%) and self-extubation (2.5%). Only 7 patients (4.5%) required tracheostomy. Regarding complications, 49% developed sepsis, 61.1% had CS, and 7% required renal replacement therapy. In-hospital mortality was 38.2% (60 patients). Conclusions IMV is a technique that is increasingly used in our environment. Patients who require it are usually complex, with multiple comorbidities, with a high percentage of CPA and CS. These patients usually have prolonged stays in the CCU, with an average of more than 10 days, frequent complications and a high in-hospital mortality of almost 40%. It is essential to gather series as large as possible of these patients to improve our knowledge of their management and characteristics.

Successful management of pulmonary edema secondary to accidental electrocution in a young dog

BackgroundHuman records describe pulmonary edema as a life-threatening complication of electric shock. Successful management requires prompt recognition and intensive care. However, in companion animals, electrocutions are rarely reported, even though domestic environments are full of electrical devices and there is always the possibility of accidental injury. Therefore, it is important for veterinarians to know more about this condition in order to achieve successful patient outcomes.Case presentationA 3-month-old male Labrador Retriever was presented with a history of transient loss of consciousness after chewing on a household electrical cord. On admission, the puppy showed an orthopneic position with moderate respiratory distress. Supplemental oxygen via nasal catheter was provided, but the patient showed marked worsening of respiratory status. Point-of-care ultrasound exams suggested neurogenic pulmonary edema due to electrical shock close to the central nervous system and increased B-lines without evidence of cardiac abnormalities. Mechanical ventilation of the patient was initiated using volume-controlled mode with a tidal volume of 9 to 15 ml/kg until reaching an end-tidal carbon dioxide ≤ 40 mm Hg, followed by a stepwise lung-recruitment maneuver in pressure-controlled mode with increases of the peak inspiratory pressure (15 to 20 cm H2O) and positive end-expiratory pressure (3 to 10 cm H2O) for 30 min, and return to volume-controlled mode with a tidal volume of 15 ml/kg until reaching a peripheral oxygen saturation ≥ 96%. Weaning from the ventilator was achieved in six hours, and the patient was discharged two days after admission without neurological or respiratory deficits.ConclusionsWe present a rather unusual case of a neurogenic pulmonary edema subsequent to accidental electrocution in a dog. Timely diagnosis by ultrasound and mechanical ventilation settings are described. Our case highlights that pulmonary edema should be considered a potentially life-threatening complication of electrical shock in small animal emergency and critical care medicine.

A prospective study on clinical profile, severity, microbiology, and outcome of patients with ventilator associated infective complications admitted in intensive care unit of a tertiary care hospital

: Mechanical ventilation epitomizes intensive care medicine. Ventilator‑associated complications are mainly Ventilator associated respiratory infections (VARI); These are a major cause of concern in the intensive care units (ICUs) worldwide, especially in developing countries. VARI includes patients with ventilator‑associated tracheobronchitis (VAT) and ventilator‑associated pneumonia (VAP).The clinical profile, severity, microbiology, and outcomes of such infections is not well described in Eastern India. The primary objective of the study was to study the risk factors, severity scoring, microbiological profile and 28 days outcome of patients admitted in intensive care unit of our hospital.Secondary objective of our study was to find out any correlation between risk factors, severity scoring, microbiological profile, and outcome of patients with VAT and VAP admitted in intensive care unit of our hospital.: This was a prospective observational study done in the ICU of a tertiary care centre in eastern India. A total 50 patients of clinically, microbiologically and/or radiologically diagnosed case of VAP and VAT were included in the study. A structured data collection proforma was prepared and data collection was done. Raw data was tabulated and analysed: 66% of our patients were male, Smoking was the commonest addiction(24%), VARI developed early with 17% on Day 3, 72% developed VARI within 5 days of ventilation. 16% had history of recent admission, Diabetes and hypertension were the commonest comorbidities. 58% of the patients developed VAP, the median SOFA score in VAP was 6 also similar in VAT. Patients with neurological diseases had the maximum number of VAT and VAP. Klebsiella pneumoniae was the commonest organism causing VAT (42%) while Acinetobacter Baumanii was commonest to cause VAP (44%). 51% of VAP patients were on volume control mode, while it was 52% of VAT patients. Most isolates are MDR pathogens with intermediate sensitivity to Polymyxin being most common (66%) 1 isolate was pan resistant. Mortality was 58% for VAP and 19% in VAT. Both Klebsiella and Acinetobacter accounts for 41% death in VAP group, in VAT group Klebsiella was commonest however no statistical significance with other organism.: Gram negative bacteria were the predominant cause of VAT and VAP, Acinetobacter and Klebsiella are the commonest organisms. Most Isolates are MDR with intermediate sensitivity to Polymyxins. Median SOFA scores were the same in both. Mortality was high in VAP group. Volume control mode was predominant mode of ventilation, Neurological causes was predominant cause that leads to ventilation and subsequent VARI.

The evaluation of a non-invasive respiratory monitor in ards patients in supine and prone position

Purpose: The Prone positioning in addition to non invasive respiratory support is commonly used in patients with acute respiratory failure. The aim of this study was to assess the accuracy of an impedance-based non-invasive respiratory volume monitor (RVM) in supine and in prone position. Methods: In sedated, paralyzed and mechanically ventilated patients in volume-controlled mode with acute respiratory distress syndrome scheduled for prone positioning it was measured and compared non-invasively tidal volume and respiratory rate provided by the RVM in supine and, subsequently, in prone position, by maintaining unchanged the ventilatory setting. Results: Forty patients were enrolled. No significant difference was found between measurements in supine and in prone position either for tidal volume (p = 0.795; p = 0.302) nor for respiratory rate (p = 0.181; p = 0.604). Comparing supine vs. prone position, the bias and limits of agreements for respiratory rate were 0.12 bpm (-1.4 to 1.6) and 20 mL (-80 to 120) for tidal volume. Conclusions: The RVM is accurate in assessing tidal volume and respiratory rate in prone compared to supine position. Therefore, the RVM could be applied in non-intubated patients with acute respiratory failure receiving prone positioning to monitor respiratory function.

Investigating the Association Between Dynamic Driving Pressure and Mortality in COVID-19-Related Acute Respiratory Distress Syndrome: A Joint Modeling Approach Using Real-Time Continuously-Monitored Ventilation Data.

COVID-19-related acute respiratory distress syndrome (ARDS) is associated with high mortality and often necessitates invasive mechanical ventilation (IMV). Previous studies on non-COVID-19 ARDS have shown driving pressure to be robustly associated with ICU mortality; however, those studies relied on "static" driving pressure measured periodically and manually. As "continuous" automatically monitored driving pressure is becoming increasingly available and reliable with more advanced mechanical ventilators, we aimed to examine the effect of this "dynamic" driving pressure in COVID-19 ARDS throughout the entire ventilation period. This retrospective, observational study cohort study evaluates the association between driving pressure and ICU mortality in patients with concurrent COVID-19 and ARDS using multivariate joint modeling. The study cohort (n = 544) included all adult patients (≥ 18 yr) with COVID-19 ARDS between March 1, 2020, and April 30, 2021, on volume-control mode IMV for 12 hours or more in a Mass General Brigham, Boston, MA ICU. Of 544 included patients, 171 (31.4%) died in the ICU. Increased dynamic ΔP was associated with increased risk in the hazard of ICU mortality (hazard ratio [HR] 1.035; 95% credible interval, 1.004-1.069) after adjusting for other relevant dynamic respiratory biomarkers. A significant increase in risk in the hazard of death was found for every hour of exposure to high intensities of driving pressure (≥ 15 cm H2O) (HR 1.002; 95% credible interval 1.001-1.003). Limiting patients' exposure to high intensities of driving pressure even while under lung-protective ventilation may represent a critical step in improving ICU survival in patients with COVID-19 ARDS. Time-series IMV data could be leveraged to enhance real-time monitoring and decision support to optimize ventilation strategies at the bedside.

Predictive values of ultrasonic diaphragm thickening fraction combined with integrative weaning index in weaning patients with mechanical ventilation: a retrospective study

ObjectiveWe aimed to explore the predictive values of ultrasonic diaphragm thickening fraction (DTF) combined with integrative weaning index (IWI) in weaning patients with mechanical ventilation.MethodsPatients with mechanical ventilation who received oral endotracheal intubation from September 2020 to September 2021 were included in this retrospective study. Before the start of the spontaneous breathing test (SBT), IWI was calculated according to the blood gas analysis parameters and parameters read in volume control mode. After the start of SBT, DTF was calculated according to the end-expiratory thickness and end-inspiratory thickness of the right diaphragm. The receiver operating curve (ROC) was used to evaluate the predictive value of DTF and IWI for successful weaning, and the sensitivity and specificity were calculated according to the best critical value.ResultsThe sensitivity, specificity, and best cutoff value of DTF to predict successful weaning was 0.772, 0.727, and 0.293, respectively, and the area under the curve (AUC) was 0.72 (95%CI 0.59–0.86, p = 0.003). The sensitivity, specificity, and best cutoff value of IWI to predict successful weaning was 0.614, 0.909, 53.00, respectively, and AUC was 0.82 (95%CI 0.72–0.91, p < 0.001). The sensitivity, specificity, and best cutoff value of the combination of DTF and IWI to predict successful weaning was 0.614, 0.909, 17.848, respectively, and AUC was 0.84 (95%CI 0.75–0.93, p < 0.001).ConclusionDTF and IWI can guide the selection of weaning, while DTF combined with IWI can improve the effect of weaning prediction and provide support for patients’ weaning safety.

Design and technical evaluation of an AMBU-BAG based low-cost ventilator-AARMED

The COVID-19 pandemic has caused a significant strain on the healthcare system worldwide, resulting in an acute shortage of ventilators. Conventional ventilators are costly, and production is difficult to scale up during a rapidly spreading pandemic. Ambu bags offer a low-cost solution for manual ventilation, but their lack of precise control over parameters makes them unsuitable as a replacement for conventional ventilators. To address this issue, we propose the AARMED (Ambu bag Attachment for Rapid Mass Emergency Deployment) system, which is a low-cost and easy-to-assemble mechanical resuscitator that can achieve most of the recommended modes and parameter ranges for managing COVID-19 patients. AARMED can operate in volume-control, pressure-control, and assist-controlled modes continuously over long periods, making it suitable for use in emergency settings. The AARMED system has been tested using an ISO certified Test-lung over various parameter settings and has been found to be an effective alternative to costly conventional ventilators. It has a battery backup of 2.5 h under normal operating conditions, making it an ideal transport ventilator. In conclusion, the AARMED system offers a low-cost and easy-to-assemble solution for mechanical ventilation in emergency settings. Its ability to achieve most of the recommended modes and parameter ranges for managing COVID-19 patients makes it a viable alternative to conventional ventilators in resource-constrained settings.

Effects of a stepwise alveolar recruitment maneuver on lung volume distribution in dogs assessed by computed tomography.

Pulmonary atelectasis is a commonly occurs during anesthesia. In these cases, mechanical ventilation (MV) associated with alveolar recruitment maneuvers (ARMs) and positive end-expiratory pressure (PEEP) is indicated to reverse the condition, ensure adequate gas exchange and improve oxygenation. ARMs can trigger volutrauma, barotrauma, and atelectrauma. Therefore, computed tomography (CT) is the gold-standard method for monitoring lung aeration after ARM. To evaluate lung volume distribution after stepwise ARMs using computed tomography (CT). Twelve dogs weighing 24.0 ± 6.0 kg, aged 3 ± 1 years, of both sexes and different breeds, underwent orchiectomy or ovariohysterectomy. The animals were anesthetized and ventilated in volume-controlled mode. ARMs were then initiated by positive end-expiratory pressure (PEEP) titration (5, 10, 15, and 20 cmH2O). CT scans, cardiovascular parameters, and ventilatory mechanics were evaluated at all time points. Data were assessed for normality using the Shapiro-Wilk test and a two-way analysis of variance, followed by a post-hoc Bonferroni test to identify differences between time points. Statistical significance was attributed to a value of p of <0.05. CT demonstrated that the ARMs increased ventilation throughout the lung, including the dependent regions, with volumes that increased and decreased proportionally with PEEP titration. When they reached PEEP 10 and 5 cmH2O descending (d), they remained significantly higher than those in PEEP 0 cmH2O (baseline). Static compliance improved about 40% at PEEP 10d and PEEP 5d compared to baseline. There was an increase in heart rate (HR) from PEEP 15 increasing (i) (74.5%) to PEEP 10d (54.8%) compared to baseline. Mean arterial blood pressure (MABP) decreased approximately 9% from PEEP 15i to PEEP 15d compared to baseline. Lung attenuation and regional and global volumes assessed by CT showed that maximum pulmonary aeration distribution followed by PEEP titration occurred at PEEP 20 cmH2O, maintaining the lungs normoaerated and without hyperaeration.

Comparison of Bilevel Volume Guarantee and Pressure-Regulated Volume Control Modes in Preterm Infants.

The present study aimed to compare the bilevel volume guarantee (VG) and pressure-regulated volume control (PRVC) modes of the GE® Carescape R860 model ventilator and test the safety and feasibility of these two modes in preterm neonates. Infants who were less than 30 weeks of gestational age were included. After randomization, initial ventilator settings were adjusted for each patient. After the first 2 h of ventilation, the patients were switched to the other ventilator mode for 2 h. The ventilator parameters, vital signs, and blood gas values were evaluated. The study included a total of 28 patients, 14 in the PRVC group and 14 in the bilevel VG group. The mean birth weight was 876 g (range: 530-1170) and the mean gestational age was 26.4 weeks (range: 24-29). The patients' peak inspiratory pressure (PIP2 and PIP3) was lower after ventilation in bilevel VG mode than in PRVC mode (13 vs. 14 cmH2O, respectively; paired samples t-test, p = 0.008). After 2 h of bilevel VG ventilation, the mean heart rate decreased from 149/min to 140/min (p = 0.001) and the oxygen saturation increased from 91% to 94% (p = 0.01). Both the PRVC and bilevel VG modes of GE ventilators can be used safely in preterm infants, and bilevel VG mode was associated with more favorable early clinical findings. Studies including more patients and comparing with other modes will clarify and provide further evidence on this subject.

Examining the haemodynamic repercussions of ventilator hyperinflation in elderly patients: An explanatory study

This study assessed the cardiovascular repercussions of two VHI (ventilation hyperinflation) protocols using the volume-controlled mode, one with an inspiratory pause (VHI-P) and the other without an inspiratory pause (VHI-NP), in mechanically ventilated elderly patients. The patients underwent both VHI protocols in a randomized order, and impedance cardiography was used to record cardiovascular variables. During VHI-P, the diastolic blood pressure was lower than during VHI-NP (Δ = 10%; p = 0.009). VHI-NP and VHI-P demonstrated a decrease in cardiac output (CO) during the first and third sets compared to baseline (p < 0.05; ES=0.23 and 0.29, respectively). Arterial oxygen delivery decreased simultaneously with CO compared to baseline values (p < 0.05; ES=0.22 and 0.23, respectively). Five minutes after the intervention, the systolic time ratio values were lower for VHI-P than VHI-NP (Δ = 10%; p = 0.01). Left ventricular ejection time values were consistently lower in VHI-NP compared to VHI-P (Δ = 2%; p = 0.02). In conclusion, our study shows that VHI in volume-controlled mode induces hemodynamic changes in mechanically ventilated elderly patients, albeit with a small effect size and within the normal range.

Design and Development of Flow Analyzer for Peak Inspiratory Flow (PIF) and Peak Expiratory Flow (PEF) Parameters.

The PIF and PEF parameters on the ventilator need to be taken into account to monitor the condition of patients undergoing mechanical ventilation. Both of these parameters need to undergo periodic testing to ensure that the ventilator can provide accurate information to its users. The testing of these two parameters can be conducted using a flow analyzer. The objective of this research is to develop a flow analyzer for PIF and PEF parameters using the AFM3000 flow sensor, with the results displayed on an LCD TFT screen in the form of graphs and numerical values. The research measurements were conducted in Volume Control (VC) mode with VT settings of 200, 300, 400, 500, and 600 mL. Data collection was done using two methods to obtain two different types of data. From the first data collection, the largest errors in reading PIF and PEF values were found to be 3.49% and 2.99%, respectively. The second data collection resulted in a sensor's change in reading constant flow of ±0.1 LPM. Overall, the research findings indicate that the AFM3000 sensor has good accuracy and stability. Additionally, the AFM3000 flow sensor has good sensitivity and very short delay, making it suitable for real-time graph display in the module.