Intermittent Mandatory Ventilation Research Articles

Comparison of neurally adjusted ventilatory assist and synchronized intermittent mandatory ventilation in preterm infants after patent ductus arteriosus ligation: a retrospective study

ObjectiveThis study aimed to compare the efficacy of neurally adjusted ventilatory assist (NAVA) to synchronized intermittent mandatory ventilation (SIMV) in preterm infants requiring mechanical ventilation after patent ductus arteriosus (PDA) ligation.MethodsA retrospective analysis was conducted on intubated preterm infants who underwent PDA ligation at our hospital from July 2021 to January 2023. Infants were divided into NAVA or SIMV groups based on the ventilation mode after surgery.ResultsFifty preterm infants were included. During treatment, peak inspiratory pressure (PIP) and mean airway pressure (MAP) were lower with NAVA compared to SIMV (PIP: 19.1 ± 2.9 vs. 22.4 ± 3.6 cmH2O, P < 0.001; MAP: 9.1 ± 1.8 vs. 10.9 ± 2.7 cmH2O, P = 0.002). PaO2 and PaO2/FiO2 were higher with NAVA (PaO2: 94.0 ± 11.7 vs. 84.8 ± 15.8 mmHg, P = 0.031; PaO2/FiO2: 267 [220–322] vs. 232 [186–290] mmHg, P = 0.025). Less sedation was required with NAVA (midazolam: 1.5 ± 0.5 vs. 1.1 ± 0.3 μg/kg/min, P < 0.001).ConclusionCompared to SIMV, early use of NAVA post PDA ligation in preterm infants was associated with decreased PIP and MAP. Early NAVA was also associated with reduced sedation needs and improved oxygenation. However, further studies are warranted to quantify the benefits of NAVA ventilation.

Respiratory entrainment related reverse triggering in mechanically ventilated children

BackgroundThe underlying pathophysiological pathways how reverse triggering is being caused are not fully understood. Respiratory entrainment may be one of these mechanisms, but both terms are used interchangeably. We sought to characterize reverse triggering and the relationship with respiratory entrainment among mechanically ventilated children with and without acute lung injury.MethodsWe performed a secondary phyiology analysis of two previously published data sets of invasively mechanically ventilated children < 18 years with and without lung injury mechanically ventilated in a continuous or intermittent mandatory ventilation mode. Ventilator waveforms, electrical activity of the diaphragm measured with surface electromyography and oesophageal tracings were analyzed for entrained and non-entrained reverse triggered breaths.ResultsIn total 102 measurements (3110 min) from 67 patients (median age 4.9 [1.8 ; 19,1] months) were analyzed. Entrained RT was identified in 12 (12%) and non-entrained RT in 39 (38%) recordings. Breathing variability for entrained RT breaths was lower compared to non-entrained RT breaths. We did not observe breath stacking during entrained RT. Double triggering often occurred during non-entrained RT and led to an increased tidal volume. Patients with respiratory entrainment related RT had a shorter duration of MV and length of PICU stay.ConclusionsReverse triggering is not one entity but a clinical spectrum with different mechanisms and consequences.Trial registrationNot applicable.

Use of Lung Ultrasound in Reducing Radiation Exposure in Neonates with Respiratory Distress: A Quality Management Project.

Background and Objectives: Our quality management project aims to decrease by 20% the number of neonates with respiratory distress undergoing chest radiographs as part of their diagnosis and monitoring. Materials and Methods: This quality management project was developed at Life Memorial Hospital, Bucharest, between 2021 and 2023. Overall, 125 patients were included in the study. The project consisted of a training phase, then an implementation phase, and the final results were measured one year after the end of the implementation phase. The imaging protocol consisted of the performance of lung ultrasounds in all the patients on CPAP (continuous positive airway pressure) or mechanical ventilation (first ultrasound at about 90 min after delivery) and the performance of chest radiographs after endotracheal intubation in any case of deterioration of the status of the patient or if such a decision was taken by the clinician. The baseline characteristics of the population were noted and compared between years 2021, 2022, and 2023. The primary outcome measures were represented by the number of X-rays performed in ventilated patients per year (including the patients on CPAP, SIMV (synchronized intermittent mandatory ventilation), IPPV (intermittent positive pressure ventilation), HFOV (high-frequency oscillatory ventilation), the number of X-rays performed per patient on CPAP/year, the number of chest X-rays performed per mechanically ventilated patient/year and the mean radiation dose/patient/year. There was no randomization of the patients for the intervention. The results were compared between the year before the project was introduced and the 2 years across which the project was implemented. Results: The frequency of cases in which no chest X-ray was performed was significantly higher in 2023 compared to 2022 (58.1% vs. 35.8%; p = 0.03) or 2021 (58.1% vs. 34.5%; p = 0.05) (a decrease of 22.3% in 2023 compared with 2022 and of 23.6% in 2023 compared with 2021). The frequency of cases with one chest X-ray was significantly lower in 2023 compared to 2022 (16.3% vs. 35.8%; p = 0.032) or 2021 (16.3% vs. 44.8%; p = 0.008). The mean radiation dose decreased from 5.89 Gy × cm2 in 2021 to 3.76 Gy × cm2 in 2023 (36% reduction). However, there was an increase in the number of ventilated patients with more than one X-ray (11 in 2023 versus 6 in 2021). We also noted a slight annual increase in the mean number of X-rays per patient receiving CPAP followed by mechanical ventilation (from 1.80 in 2021 to 2.33 in 2022 and then 2.50 in 2023), and there was a similar trend in the patients that received only mechanical ventilation without a statistically significant difference in these cases. Conclusions: The quality management project accomplished its goal by obtaining a statistically significant increase in the number of ventilated patients in which chest radiographs were not performed and also resulted in a more than 30% decrease in the radiation dose per ventilated patient. This task was accomplished mainly by increasing the number of patients on CPAP and the use only of lung ultrasound in the patients on CPAP and simple cases.

Prognostic factors in an individualised approach to non-pharmacological therapy of COVID-19: from oxygen and mechanical ventilation to extracorporeal membrane oxygenation

Our centre followed a stepwise approach in the nonpharmacological treatment of respiratory failure in COVID-19 in accordance with German national guidelines, escalating non-invasive measures before invasive mechanical ventilation (IMV) or extracorporeal membrane oxygenation (ECMO). The aim of this study was to analyse this individualized approach to non-pharmacologic therapy in terms of patient characteristics and clinical features that may help predict more severe disease, particularly the need for intensive care. This retrospective single-centre study of COVID-19 inpatients between March 2020 and December 2021 analysed anthropometric data, non-pharmacological maximum therapy and survival status via a manual medical file review. Of 1052 COVID-19-related admissions, 835 patients were included in the analysis cohort (54% male, median 58 years); 34% (n=284) received no therapy, 40% (n=337) conventional oxygen therapy (COT), 3% (n=22) high flow nasal cannula (NHFC), 9% (n=73) continuous positive airway pressure (CPAP), 7% (n=56) non-invasive ventilation (NIV), 4% (n=34) intermittent mandatory ventilation (IMV), and 3% (n=29) extracorporeal membrane oxygenation (ECMO). Of 551 patients treated with at least COT, 12.3% required intubation. A total of 183 patients required ICU treatment, and 106 (13%) died. 25 (74%) IMV patients and 23 (79%) ECMO patients died. Arterial hypertension, diabetes and dyslipidemia was more prevalent in non-survivors. Binary logistic analysis revealed the following risk factors for increased mortality: an oxygen supplementation of ≥2 L/min at baseline (OR 6.96 [4.01-12.08]), age (OR 1.09 [1.05-1.14]), and male sex (OR 2.23 [0.79-6.31]). The physician's immediate clinical decision to provide oxygen therapy, along with other recognized risk factors, plays an important role in predicting the severity of the disease course and thus aiding in the management of COVID-19.

Machine learning algorithm for ventilator mode selection, pressure and volume control.

Mechanical ventilation techniques are vital for preserving individuals with a serious condition lives in the prolonged hospitalization unit. Nevertheless, an imbalance amid the hospitalized people demands and the respiratory structure could cause to inconsistencies in the patient's inhalation. To tackle this problem, this study presents an Iterative Learning PID Controller (ILC-PID), a unique current cycle feedback type controller that helps in gaining the correct pressure and volume. The paper also offers a clear and complete examination of the primarily efficient neural approach for generating optimal inhalation strategies. Moreover, machine learning-based classifiers are used to evaluate the precision and performance of the ILC-PID controller. These classifiers able to forecast and choose the perfect type for various inhalation modes, eliminating the likelihood that patients will require mechanical ventilation. In pressure control, the suggested accurate neural categorization exhibited an average accuracy rate of 88.2% in continuous positive airway pressure (CPAP) mode and 91.7% in proportional assist ventilation (PAV) mode while comparing with the other classifiers like ensemble classifier has reduced accuracy rate of 69.5% in CPAP mode and also 71.7% in PAV mode. An average accuracy of 78.9% rate in other classifiers compared to neutral network in CPAP. The neural model had an typical range of 81.6% in CPAP mode and 84.59% in PAV mode for 20 cm H2O of volume created by the neural network classifier in the volume investigation. Compared to the other classifiers, an average of 72.17% was in CPAP mode, and 77.83% was in PAV mode in volume control. Different approaches, such as decision trees, optimizable Bayes trees, naive Bayes trees, nearest neighbour trees, and an ensemble of trees, were also evaluated regarding the accuracy by confusion matrix concept, training duration, specificity, sensitivity, and F1 score.

High vs Low PEEP in Patients With ARDS Exhibiting Intense Inspiratory Effort During Assisted Ventilation: A Randomized Crossover Trial

BackgroundPEEP can potentially modulate inspiratory effort (ΔPes), which is the major determinant of self-inflicted lung injury. Research questionDoes high PEEP reduce ΔPes in moderate-to-severe ARDS patients on assisted ventilation? Study Design and MethodsSixteen patients with PaO2/FiO2≤200 mmHg and ΔPes≥10 cmH2O underwent a randomized sequence of four ventilator settings: PEEP=5 cmH2O or PEEP=15 cmH2O + synchronous (pressure support ventilation, PSV) or asynchronous (pressure-controlled intermittent mandatory ventilation, PC-IMV) inspiratory assistance. ΔPes, respiratory system, lung and chest-wall mechanics were assessed with esophageal manometry and occlusions. PEEP-induced alveolar recruitment and overinflation, lung dynamic strain and tidal volume distribution were assessed with electrical impedance tomography. ResultsΔPes was not systematically different at high vs. low PEEP (PSV: median 20 [15-24] cmH2O vs. 15 [13-23], p=0.24; PC-IMV: 20 [18-23] vs. 19 [17-25], p=0.67). Similarly, respiratory system and transpulmonary driving pressure, tidal volume, lung/chest-wall mechanics and pendelluft extent were not different between study phases. High PEEP resulted in lower or higher ΔPes, respiratory system and transpulmonary driving pressure according to whether this increased or decreased respiratory system compliance, respectively (r=-0.85, p<0.001; r=-0.75, p<0.001; r=-0.80, p<0.001, respectively). PEEP-induced changes in respiratory system compliance were driven by its lung component and were dependent on the extent of PEEP-induced alveolar overinflation (r=-0.66, p=0.006). High PEEP caused variable recruitment and systematic redistribution of tidal volume towards dorsal lung regions, thereby reducing dynamic strain in ventral areas (PSV: 0.49 [0.37-0.83] vs. 0.96 [0.62-1.56], p=0.003; PC-IMV: 0.65 [0.42-1.31] vs. 1.14 [0.79-1.52], p=0.002). All results were consistent during synchronous and asynchronous inspiratory assistance. InterpretationThe impact of high PEEP on ΔPes and lung stress is inter-individually variable according to different effects on respiratory system and lung compliance resulting from alveolar overinflation. High PEEP may help mitigate the risk of self-inflicted lung injury solely if it increases lung/respiratory system compliance.

Cough and sputum in long COVID are associated with severe acute COVID-19: a Japanese cohort study

BackgroundMultiple prolonged symptoms are observed in patients who recover from acute coronavirus disease 2019 (COVID-19), defined as long COVID. Cough and sputum are presented by patients with long COVID during the acute and post-acute phases. This study aimed to identify specific risk factors for cough and sputum in patients with long COVID.MethodsHospitalized patients with COVID-19 aged 18 years were enrolled in a multicenter cohort study at 26 medical institutions. Clinical data during hospitalization and patient-reported outcomes after discharge were collected from medical records, paper-based questionnaires, and smartphone apps.ResultsAt the 3-, 6-, and 12-month follow-ups, there were no differences in the incidence rates of wet and dry coughs. In contrast, the proportion of patients presenting sputum without coughing increased over time compared to those with sputum and coughing. Univariate analyses of cough and sputum at all follow-up visits identified intermittent mandatory ventilation (IMV), smoking, and older age as risk factors for prolonged symptoms. At the 12-month follow-up, persistent cough and sputum were associated with the characteristics of severe COVID-19 based on imaging findings, renal and liver dysfunction, pulmonary thromboembolism, and higher serum levels of LDH, KL-6, and HbA1C. The Kaplan–Meier curves showed that the severity of acute COVID-19 infection was correlated with prolonged cough and sputum production. Multivariable logistic regression analysis showed that IMV ventilator management were independent risk factors for prolonged cough and sputum at 12 months.ConclusionsIn a Japanese population with long COVID, prolonged cough and sputum production were closely associated with severe COVID-19. These findings emphasize that a preventive approach including appropriate vaccination and contact precaution and further development of therapeutic drugs for COVID-19 are highly recommended for patients with risk factors for severe infection to avoid persistent respiratory symptoms.

Abstract 218: Effect of Airway Pressure and Localized Sternal Compression Upon Hemodynamics During Cardiopulmonary Resuscitation

Background: During cardiopulmonary resuscitation (CPR), chest compression (CC) and mechanical ventilation are cyclic in nature and each modulate the intrathoracic pressure (ITP). ITP is increased during the compression phase of CC, causing an increase in aortic pressure (AoP) and right atrial pressure (RAP) to drive forward blood flow. Similarly, positive pressure ventilation increases ITP during the inspiratory phase as pressure is transmitted through the lungs, which also has an impact on hemodynamics. The purpose of this analysis was to examine differences in hemodynamics during ventricular fibrillation (VF) arrest due to ventilation alone and during localized sternal CC of varying depths in a porcine model of cardiac arrest. Methods: Domestic swine (n = 8) underwent electrically induced VF with ten-minute downtime, followed by resuscitation with mechanical ventilation and CC with active lift to neutral chest position. Mechanical ventilation was delivered using pressure-controlled synchronized intermittent mandatory ventilation (SIMV) mode (Vt 10 mL/kg, 10 bpm, trigger -6 cmH 2 O, PEEP 5 cmH 2 O, FiO 2 100). CPR was initiated with three minutes of ventilation only, followed by one minute of break-in CC at 1.0 in and 1.5 in prior to increase to depth of 2.0 in. AoP, RAP, esophageal pressure (Pes), and airway pressure (Paw) were examined over the ventilation cycle to determine the effect of each treatment upon parameters. Results: Positive pressure ventilation caused similar changes to the Pes, RAP, and AoP values (3-5 mmHg). CC caused similar changes to Pes (3-5 mmHg), but much larger changes to the RAP and AoP (10-130 mmHg) depending on compression depth. Conclusions: The ITP is not uniform during CC, creating only modest changes to Pes. This suggests that CC generate blood pressures, and presumably flows, through mechanisms other than ITP modulation. Understanding this interaction could improve our understanding of blood flow during CPR.

Study of Organophosphorus Poisoning at a Tertiary Care Teaching Hospital

Introduction: Organophosphate (OP) insecticides inhibit both cholinesterase and pseudo-cholinesterase activities. The inhibition of acetylcholinesterase causes accumulation of acetylcholine at synapses, and overstimulation of neurotransmission occurs as a result of this accumulation. The mortality rate of OP poisoning is high. Early diagnosis and appropriate treatment is often life saving. Treatment of OP poisoning consists of intravenous atropine and oximes. The clinical course of OP poisoning may be quite severe and may need intensive care management. Methods: A retrospective study was performed on the patients with OP poisoning. Fifty patients were included. Diagnosis was performed from the history taken either from the patient or from the patient's relatives about the agent involved in the exposure. Diagnosis could was confirmed with serum and red blood cell anticholinesterase levels. Intravenous atropine and pralidoxime was administered as soon as possible. Other measures for the treatment were gastric lavage and administration of activated charcoal via nasogastric tube, and cleansing the patient's body with soap and water. The patients were intubated and mechanically ventilated if the patients had respiratory failure, a depressed level of consciousness, which causes an inability to protect the airway, and hemodynamic instability. Mechanical ventilation was performed as synchronized intermittent mandatory ventilation + pressure support mode, either as volume or pressure control. Positive end expiratory pressure was titrated to keep SaO2 above 94% with 40% FIO2. Weaning was performed using either T-tube trials or pressure support weaning. The chi-square test was used for statistical analysis. Data are presented as mean ± standard deviation. Results: There were 26 female and 24 male patients. Thirty-five were suicide attempts and 15 were accidental exposure. The gastrointestinal route was the main route in 44 patients. The most frequent signs were meiosis, change in mental status, hypersalivation and fasciculations. Ten patients (20.0%) required mechanical ventilation. Complications were observed in 35 patients. These complications were respiratory failure (14 patients), aspiration pneumonia (10 patients), urinary system infection (6 patients), convulsion (4 patients) and septic shock (1 patient). The duration of the intensive care stay was 5.2 ± 3.0 days. Discussion: Ingestion of OP compounds for suicidal purposes is a major problem, especially in developing countries. Thirty-five of our patients used the OP insecticide for suicide. The average respiratory rate of these patients increased from 22 to 38 breaths/min, which is an important sign of respiratory distress. The nurse to patient ratio was increased after these events. Early recognition of respiratory failure resulting in intubation and mechanical ventilation is a life-saving intervention for patients with OP poisoning. Respiratory failure is the most troublesome complication, which was observed in 35 patients. Patients with OP poisoning may have respiratory failure for many reasons, including aspiration of the gastric content, excessive secretions, pneumonia and septicemia complicating acute respiratory distress syndrome. Conclusions: OP insecticide poisoning is a serious condition that needs rapid diagnosis and treatment. Since respiratory failure is the major reason for mortality, careful monitoring, appropriate management and early recognition of this complication may decrease the mortality rate among these patients.

Effect of different ventilation methods combined with pulmonary surfactant on neonatal acute respiratory distress syndrome.

Acute respiratory distress syndrome precipitates is widespread pulmonary injury in impacted individuals, the neonatal respiratory distress syndrome (NRDS), primarily observed in preterm infants, represents a prevalent critical condition in neonatal clinical settings. To investigate the clinical efficacy of various ventilation strategies combined with pulmonary surfactant (PS) therapy in the treatment of NRDS. A total of 20 neonates diagnosed with respiratory distress syndrome, admitted between May 2021 and June 2022, were randomly assigned to either a research group or a control group. Neonates in the research group received treatment involving high-frequency oscillatory ventilation (HFOV) in conjunction with PS. In contrast, neonates in the control group were administered either controlled mechanical ventilation or synchronous intermittent mandatory ventilation, combined with PS. Arterial blood samples from the neonates in both groups were collected before treatment, as well as 6 h, 12 h, 24 h, and 48 h post-treatment. These samples underwent blood gas analysis, with measurements taken for pH value, partial pressures of oxygen (O2) and carbon dioxide. Concurrently, data was collected on the duration of ventilator use, length of hospitalization time, O2 treatment time, treatment outcomes, and complications of the ventilator. From 6-48 h post-treatment, both groups demonstrated significant improvements in arterial blood pH and oxygen partial pressure, along with a significant decrease in carbon dioxide partial pressure compared to pre-treatment values (P < 0.05). Although these changes progressed over time, there were no significant differences between the two groups (P > 0.05). However, the research group had significantly lower X-ray scores, shorter hospitalization time, and less time on O2 therapy compared to the control group (P < 0.05). Mortality rates were similar between the two groups (P > 0.05), but the research group had a significantly lower incidence of complications (P < 0.05). The integration of HFOV combine with PS has proven to effectively expedite the treatment duration, decrease the occurrence of complications, and secure the therapeutic efficacy in managing NRDS.

Comparison of clinical outcomes in critical patients undergoing different mechanical ventilation modes: a systematic review and network meta-analysis.

To evaluate the effects of different mechanical ventilation modes on critical patients. PubMed, Embase, Web of science, and Cochrane Library databases were searched from their inception to November 15, 2022 for randomized controlled trials on the application of different mechanical ventilation modes in critical patients. Two researchers independently screened the literature, extracted data, and assessed the risk of bias in the included studies. R4.2.1 was used for this network meta-analysis. Twenty-eight RCTs involving 3,189 patients were included. The interventions in these RCTs included NAVA (neurally adjusted ventilatory assist), PAV (proportional assist ventilation), ASV (adaptive support ventilation), Smartcare/PS (Smartcare/pressure support), PSV (pressure support ventilation), PSV_ATC (pressure support ventilation_automatic tube compensation), and SIMV (synchronized intermittent mandatory ventilation). The network meta-analysis showed that, compared with the PSV group, there was no significant difference in duration of mechanical ventilation, duration of ICU stay, and hospital stay between NAVA, SIMV, AVS, PAV, Smartcare/PS, and PSV_ATC groups. Compared with PSV, PAV improved the success rate of withdrawal of ventilator [OR = 3.07, 95%CI (1.21, 8.52)]. Compared with PSV and PAV, NAVA reduced mortality in the ICU [OR = 0.63, 95%CI (0.43, 0.93); OR = 0.45, 95%CI (0.21, 0.97)]. NAVA can reduce mortality in ICU, and PAV may increase the risk of withdrawal of the ventilator. There was no significant difference between PSV and other mechanical ventilation modes (NAVA, SIMV, AVS, PAV, Smartcare/PS, and PSV_ATC) in the duration of mechanical ventilation, duration of ICU stay, or hospital stay. Due to the limitations, more high-quality studies are needed to verify these findings.

The Impact of High-Frequency Chest-Wall Compression on Mechanical Ventilation Delivery and Flow Bias.

It is unclear if high-frequency chest-wall compression (HFCWC) has a role to assist with secretion clearance in patients on mechanical ventilation. The effect of HFCWC on the delivery of mechanical ventilation is unknown. This study describes the effect of HFCWC on mechanical ventilation delivery and flow bias in an orally intubated and mechanically ventilated bench model. An orally intubated mannequin was mechanically ventilated in 5 commonly used modes of ventilation at settings that reflect current practice. HFCWC was applied via a randomized combination of oscillation frequencies and pressure settings. Mechanical ventilator flow, flow bias, and breathing frequency were measured before and during the application of HFCWC. HFCWC led to 3- to 7-fold increases in ventilator-delivered breathing frequency during synchronized intermittent mandatory ventilation, bi-level (with pressure support), bi-level-assist, and pressure-regulated volume control modes of ventilation. Only in the bi-level mode without pressure support was the ventilator breathing frequency unaffected by HFCWC. During HFCWC, peak inspiratory flow to peak expiratory flow ratios toward an expiratory flow bias, particularly at higher HFCWC pressures, only in pressure-regulated volume control and synchronized intermittent mandatory ventilation modes were peak inspiratory flow to peak expiratory flow ratios of <0.9 generated that would facilitate secretion clearance. HFCWC led to 3- to 7-fold increases in ventilator breathing frequency delivered by mechanical ventilation except in the bi-level mode. The bi-level mode may be the optimal mode to use HFCWC to minimize disruption to the delivered ventilator breathing frequency. The peak inspiratory flow to peak expiratory flow ratios < 0.9, the optimal flow bias for secretion clearance, was only achieved in the pressure-regulated volume control and synchronized intermittent mandatory ventilation modes. However, the findings in this bench model with a fixed low compliance may not be generalizable to the patient in the ICU, and we recommend further investigation into the effects of HFCWC in the patient in the ICU.

Feasibility of ventilator-assisted tubeless anesthesia for video-assisted thoracoscopic surgery.

General anesthesia providing one-lung ventilation (OLV) with double-lumen endotracheal intubation has been considered inevitable for thoracic surgery. However, with the recent trend of less invasive surgical technique and enhanced recovery after surgery, tubeless anesthesia has been performed in various thoracic surgeries. The aim of this study was to establish a feasible and safe strategy of ventilator-assisted tubeless anesthesia in video-assisted thoracoscopic surgeries (VATS) based on single-institution experiences. We retrospectively reviewed the medical records of patients who underwent tubeless VATS from November 2019 to December 2021. Perioperative anesthetic and surgical variables as well as complications were reported. Seventeen patients with a median age of 29 and American Society of Anesthesiologists physical status I to II underwent video-assisted pulmonary wedge resection under monitored anesthesia care (MAC) using propofol and remifentanil. Mechanical ventilation was applied in synchronized intermittent mandatory ventilation with pressure support mode through facemask if respiratory support was required. During the operation, none of the patients showed hypoxemia or involuntary movement interfering operation. No patients were converted to general anesthesia or open thoracotomy unintentionally. All patients were discharged on median 2 days postoperatively without complications. Ventilator-assisted tubeless VATS is a feasible and safe option in low-risk patients undergoing video-assisted pulmonary wedge resection.

Maintaining an acceptable indoor air quality of spaces by intentional natural ventilation or intermittent mechanical ventilation with minimum energy use

Ventilation is essential for maintaining good indoor air quality (IAQ). However, many buildings continue to suffer from inadequate ventilation due to a lack of either sufficient natural ventilation or proper operation of mechanical ventilation. During the pandemic of COVID-19, several Chinese guidelines have suggested that the household rooms for isolating infected persons and the classrooms that are not equipped with mechanical ventilation should open the windows for at least 30 min twice a day. This study first investigated whether this way of natural ventilation could ensure an acceptable IAQ. Then, the relationships between ventilation duration, ventilation frequency, and IAQ under different air change rates per hour (ACH) were examined to understand how to optimize ventilation design and operation in an efficient manner. When the ACH is ≥ 6 h−1, an acceptable IAQ can be achieved under the recommended ventilation frequency. An increase in ACH would improve the IAQ and reduce the IAQ difference caused by different CO2 generation rate per unit volume (Gr/V) values. Furthermore, simply increasing single ventilation duration while maintaining constant ventilation frequency is not an effective way to improve IAQ, as the improvement decreases as the ventilation duration is increased. Finally, when total ventilation duration is constant, increasing ventilation frequency can significantly improve the ventilation efficiency and thus IAQ, laying the groundwork for ventilation design that balances IAQ and energy use. The findings provide feasible and economical solutions for ventilation of buildings where conventional mechanical ventilation systems are not affordable.

Evaluation of IntelliVent-ASV® and PS-SIMV Mode Using Ultrasound (US) Measurements in Terms of Diaphragm Atrophy.

Mechanical ventilation is a life-saving intervention for critically ill patients, but it can also lead to diaphragm atrophy, which may prolong the duration of mechanical ventilation and the length of stay in the intensive care unit. IntelliVent-ASV® (Hamilton Medical, Rhäzüns, Switzerland) is a new mode of ventilation that has been developed to reduce diaphragm atrophy by promoting spontaneous breathing efforts. In this study, we aimed to evaluate the effectiveness of IntelliVent-ASV® and pressure support-synchronized intermittent mandatory ventilation (PS-SIMV) mode in reducing diaphragm atrophy by measuring diaphragm thickness using ultrasound (US) imaging. We enrolled 60 patients who required mechanical ventilation due to respiratory failure and were randomized into two groups: IntelliVent-ASV®and PS-SIMV. We measured the diaphragm thickness using US imaging at admission and on the seventh day of mechanical ventilation. Our results showed that diaphragm thickness decreased significantly in the PS-SIMV group but remained unchanged in the IntelliVent-ASV®group. The difference in diaphragm thickness between the two groups was statistically significant on the seventh day of mechanical ventilation. IntelliVent-ASV®may reduce diaphragm atrophy by promoting spontaneous breathing efforts. Our study suggests that this new mode of ventilation may be a promising approach to preventing diaphragm atrophy in mechanically ventilated patients. Further studies using invasive measures of diaphragm function are warranted to confirm these findings.

Impact of pressure-targeted modes of ventilation on diaphragmatic function as assessed using ultrasonography in critically ill patients with cerebral insult: a randomized clinical trial

BackgroundMechanical ventilation causes diaphragmatic atrophy and reduces diaphragmatic efficiency. Patients with diaphragmatic dysfunction have longer mechanical ventilation durations and intensive care unit stay. There is currently a scarcity of data on the effect of different modes of mechanical ventilation on diaphragmatic function and ultrasound-guided assessment of diaphragmatic efficiency.ResultsSixty mechanically ventilated patients were randomly divided into four equal groups (15 each): patients were ventilated using either assist control pressure-controlled mode (group A), synchronized intermittent mandatory ventilation pressure-controlled mode (group S), bi-level-positive airway pressure mode (group B) or pressure support ventilation mode (group P). The primary outcome was to assess the diaphragmatic excursion, while the secondary outcomes were to assess the diaphragmatic thickness fraction and the duration of the ICU stay. Patients in the P group had the highest diaphragmatic excursion indicating better diaphragmatic function.ConclusionsWhen compared to other pressure-targeted ventilation modes, the pressure support ventilation mode may have the least risk of diaphragmatic dysfunction as preserves diaphragmatic structure and strength.Trial registrationThe clinical trial was retrospectively registered at http://www.pactr.org PACTR202112653971335.

The effect of APRV-LTV mechanical ventilation mode on SpO2 and ventilation indices in patients with COVID-19

Background &amp; Aim: Mechanical ventilation is a life-saving method for acute respiratory distress syndrome. The present study aimed to investigate the impact of airway pressure release ventilation-low tidal volume mode on COVID-19 patients’ peripheral capillary oxygen saturation and ventilation indices.&#x0D; Methods &amp; Materials: This clinical trial was conducted on 70 COVID-19 patients hospitalized in the Intensive care unit in Qom, Iran. Patients were selected using convenience sampling and randomly allocated to intervention and control groups. In the control group, patients were ventilated using synchronized intermittent mandatory ventilation mode, and in the intervention group, patients were ventilated using airway pressure release ventilation-low tidal volume mode. Patients’ peripheral capillary oxygen saturation and ventilation indices were checked and recorded before and after the intervention. The data were analyzed using SPSS 11.5.&#x0D; Results: According to the results of the repeated-measures ANOVA test before the intervention and the 2 and 4 hours after the intervention, there were no significant differences between the intervention and control groups regarding the fraction of inspired oxygen, volume minute per minute, and peripheral capillary oxygen saturation (P&gt;0.05). However, in the intervention group compared to the control group, the mean of PIP was significantly reduced (P&lt;0.05).&#x0D; Conclusion: In patients with COVID-19, the two modes of mechanical ventilation, APRV, and control, had no significant differences in the fraction of inspired oxygen, volume minute per minute, and peripheral capillary oxygen saturation. However, the mean peak inspiratory pressure reduction in the intervention group was greater than that in the control group. Considering that several factors can affect peripheral capillary oxygen saturation and ventilation indices, these results should be considered with caution.

PULM6: Exploratory In Vivo Testing Of A Non-Invasive Ventilation Assist Device

Background: Mechanical ventilation is normally accomplished by positive pressure, either invasively through an endotracheal tube, or non-invasively through a mask or nasal prongs. Positive pressure ventilation (PPV) is associated with ventilator induced lung injury (VILI), especially in infants. Negative pressure ventilation (NPV) is more physiologic and preferentially opens posterior areas of the sick lung refractory to opening with positive pressure ventilation alone. However, NPV is not widely used due to the cumbersome negative air pressure chambers requiring torso and neck seals. Methods: We have developed a more practical device for achieving NPV. The Torso Expander consists of flexible tubes attached to a base layer which adheres to the torso with a silicone skin adhesive. Positive air pressure applied to the tubes causes elongation of the tubes and a distending pressure on the torso. The distending pressure may be static or cycled on and off (Torso Assist Ventilation - TAV) at a manual rate, or synchronized to the patient’s respiration (spontaneous or ventilator induced). The Torso Expander, sized for infants, was tested acutely in 5 piglets (3.1+/- 0.2 kg) during normal physiologic states as well as simulated ARDS by saline lavage surfactant washout, and simulated neuromuscular dysfunction by rocuronium paralysis, in order to study the biomechanics and potential clinical applications with various testing modes. Results: In the ARDS model, when static inflation (up to 400 mmHg) was added to the synchronized intermittent mandatory ventilation (SIMV) for a period of 17 min, intra-abdominal pressure was reduced by 1.0-1.5 cm-water per 100 mmHg inflation pressure, average tidal volume (TV) was increased by 5ml, and average respiratory rate was decreased by 27/min compared to the baseline SIMV. Gastric pressure, which may be measured less invasively in clinical use, correlated linearly (r2 > 0.94) with intra-abdominal pressure. TAV, synchronized with spontaneous and ventilator breaths, was demonstrated, resulting in increases in TV. During static and TAV support oxygenation improved (PaO2/FiO2 increased from 69 to 222 mmHg on average after the interventions). TAV alone was able to support a TV of 5 ml/kg with the animal paralyzed. Discussion: Exploratory studies demonstrated the beneficial effects of this novel non-invasive method of NPV. Additional studies are underway to further quantify these observations and test the technology in adults. This technology may reduce the time on PPV, or avoid PPV in some cases.

Weaning in neurally adjusted ventilatory assist: a prospective interventional study in neonates.

Neurally adjusted ventilatory assist (NAVA) is a respiratory support triggered by the electrical activity of the diaphragm (EAdi). Only few studies evaluated NAVA short-term efficacy and safety in newborns. Aim of this study was to assess efficacy and safety of NAVA in a cohort of newborns and to analyze ventilation parameters helpful to guide weaning. Thirty-four newborns with respiratory failure were ventilated with synchronized intermittent mandatory ventilation plus pressure-regulated volume control plus pressure support (SIMV(PRVC)+PS) for 12 hours and switched to NAVA until extubation. Ventilator and vital parameters, oxygen saturation (SpO2)/fraction of inspired oxygen (FiO2) ratio (S/F), arterialized capillary blood gases (aCBG), and sedatives dose were recorded. The occurrence of reintubation within the first 72 hours, pneumothorax and mortality were evaluated. After 6 hours of NAVA, a significant reduction of FiO2 (0.25 versus 0.32), and peak inspiratory pressure (13 versus 18 mmHg), and a significant increase of S/F (383 versus 316) were found, compared to SIMV(PRVC)+PS. Other ventilation, vital and aCBG parameters were similar in both ventilation modes. During NAVA a significant reduction of sedation was shown. All subjects were successfully extubated guided by EAdi peak during weaning. No reintubation, pneumothorax, or death were recorded. NAVA can be effectively and safely used in neonates. The EAdi peak could be a reliable index to guide the physicians during weaning and extubation.

Effect of the change of mechanical ventilation mode on cerebral oxygen saturation level in neonates

BackgroundThis study aimed to apply near-infrared spectroscopy (NIRS) to monitor cerebral oxygen saturation (SrO2) level in neonates before and after the change of mechanical ventilation mode, and thus, the effects of the change of mechanical ventilator mode on SrO2 level in neonates were assessed.MethodsThis trial was designed as an observational study .A total of 70 neonates who were admitted to the Department of Neonatology of Beijing Luhe Hospital Affiliated to Capital Medical University (Beijing, China) between September 2019 and October 2021 and required respiratory support were included. The variations of SrO2 level before and after the change of mechanical ventilation mode, including changing from Synchronized intermittent mandatory ventilation (SIMV) to noninvasive ventilation (NIV, group 1), and from NIV to oxygen inhalation (group 2), were monitored by Enginmed EGOS-600 A. The changes of SrO2 level at 30 min before and 1 h after the change of ventilation mode were compared between the two groups.ResultsThe SrO2 level in the group 1 30 min before, as well as 10 min, 30 min, and 1 h after the change of ventilation mode was 62.54 ± 3.36%, 65.43 ± 3.98%, 64.38 ± 4.23%, and 64.63 ± 3.71%, respectively. The SrO2 level at all the points after the change of ventilation mode increased compared with 30 min before the change (P < 0.05). The SrO2 level in the group 2 at each time point was 62.67 ± 4.69%, 64.61 ± 5.00%, 64.04 ± 4.48%, and 64.55 ± 4.32%, respectively. Compared with 30 min before ventilator weaning, the SrO2 level at all the points after ventilator weaning increased (P < 0.05). Peak inspiratory pressure (PIP) excluding Nasal Continuous Positive Airway Pressure (NCPAP)) in group 1 was lower than that before extubation, and the difference was statistically significant (P = 0) (Table 7).ConclusionsSrO2 level showed an increasing trend after the change of ventilation mode, and the increase of SrO2 level at 10 min after the change of ventilation mode was the most prominent. From SIMV to NIV, increased SrO2 levels may be associated with decreased PIP.