Pressure-regulated Volume Control Research Articles

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.

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.

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.

Lung recruitment by continuous negative extra-thoracic pressure support following one-lung ventilation: an experimental study.

Lung recruitment maneuvers following one-lung ventilation (OLV) increase the risk for the development of acute lung injury. The application of continuous negative extrathoracic pressure (CNEP) is gaining interest both in intubated and non-intubated patients. However, there is still a lack of knowledge on the ability of CNEP support to recruit whole lung atelectasis following OLV. We investigated the effects of CNEP following OLV on lung expansion, gas exchange, and hemodynamics. Ten pigs were anesthetized and mechanically ventilated with pressure-regulated volume control mode (PRVC; FiO2: 0.5, Fr: 30-35/min, VT: 7mL/kg, PEEP: 5 cmH2O) for 1hour, then baseline (BL) data for gas exchange (arterial partial pressure of oxygen, PaO2; and carbon dioxide, PaCO2), ventilation and hemodynamical parameters and lung aeration by electrical impedance tomography were recorded. Subsequently, an endobronchial blocker was inserted, and OLV was applied with a reduced VT of 5mL/kg. Following a new set of measurements after 1h of OLV, two-lung ventilation was re-established, combining PRVC (VT: 7mL/kg) and CNEP (-15 cmH2O) without any hyperinflation maneuver and data collection was then repeated at 5min and 1h. Compared to OLV, significant increases in PaO2 (154.1 ± 13.3 vs. 173.8 ± 22.1) and decreases in PaCO2 (52.6 ± 11.7 vs. 40.3 ± 4.5mmHg, p < 0.05 for both) were observed 5minutes following initiation of CNEP, and these benefits in gas exchange remained after an hour of CNEP. Gradual improvements in lung aeration in the non-collapsed lung were also detected by electrical impedance tomography (p < 0.05) after 5 and 60min of CNEP. Hemodynamics and ventilation parameters remained stable under CNEP. Application of CNEP in the presence of whole lung atelectasis proved to be efficient in improving gas exchange via recruiting the lung without excessive airway pressures. These benefits of combined CNEP and positive pressure ventilation may have particular value in relieving atelectasis in the postoperative period of surgical procedures requiring OLV.

Utilizing Spontaneous Ventilation Modes in Patients Underwent Corrective Surgery for Right Ventricular Outflow Tract Obstructive Congenital Heart Disease: A Crossover Study

Background: This study aimed to determine whether the hemodynamics of patients with right ventricle outflow tract obstructive congenital heart disease (RVOTO-CHD) improve after corrective surgery by changing the ventilation mode. Methods: Patients with RVOTO-CHD who underwent corrective surgery were enrolled in this study. Echocardiography and advanced hemodynamic monitoring were performed using the pulse indicator continuous cardiac output (PiCCO) technology in the pressure-regulated volume control (PRVC) mode, followed with switching to the pressure support ventilation (PSV) mode and neurally adjusted ventilatory assist (NAVA) mode in random order. Results: Overall, 31 patients were enrolled in this study from April 2021 to October 2021. Notably, changing the ventilation mode from PRVC to a spontaneous mode (PSV or NAVA) led to better cardiac function outcomes, including right ventricular cardiac index (PRVC: 3.19 ± 1.07 L/min/m2 vs. PSV: 3.45 ± 1.32 L/min/m2 vs. NAVA: 3.82 ± 1.03 L/min/m2, p &lt; 0.05) and right ventricle contractility (tricuspid annular peak systolic velocity) (PRVC: 6.58 ± 1.40 cm/s vs. PSV: 7.03 ± 1.33 cm/s vs. NAVA: 7.94 ± 1.50 cm/s, p &lt; 0.05), as detected via echocardiography. Moreover, in the NAVA mode, PiCCO-derived cardiac index (PRVC: 2.92 ± 0.54 L/min/m2 vs. PSV: 3.04 ± 0.56 L/min/m2 vs. NAVA: 3.20 ± 0.62 L/min/m2, p &lt; 0.05), stroke volume index (PRVC: 20.38 ± 3.97 mL/m2 vs. PSV: 21.23 ± 4.33 mL/m2 vs. NAVA: 22.00 ± 4.33 mL/m2, p &lt; 0.05), and global end diastolic index (PRVC: 295.74 ± 78.39 mL/m2 vs. PSV: 307.26 ± 91.18 mL/m2 vs. NAVA: 323.74 ± 102.87 mL/m2, p &lt; 0.05) improved, whereas extravascular lung water index significantly reduced (PRVC: 16.42 ± 7.90 mL/kg vs. PSV: 15.42 ± 5.50 mL/kg vs. NAVA: 14.4 ± 4.19 mL/kg, p &lt; 0.05). Furthermore, peak inspiratory pressure, mean airway pressure, driving pressure, and compliance of the respiratory system improved in the NAVA mode. No deaths were reported in this study. Conclusions: We found that utilizing spontaneous ventilator modes, especially the NAVA mode, after corrective surgery in patients with RVOTO-CHD may improve their right heart hemodynamics and respiratory mechanics. However, further randomized controlled trials are required to verify the advantages of spontaneous ventilation modes in such patients. Clinical Trial Registration: NCT04825054.

Comparison of Mechanical Power Calculations of Volume Control and Pressure Regulated Volume Control Modes: A Prospective Observational Study

Comparison of Mechanical Power Calculations of Volume Control and Pressure Regulated Volume Control Modes: A Prospective Observational Study

Optimizing One-Lung Ventilation in Thoracic Surgery—Does Mode of Ventilation Matter?

Postoperative Hypoxemia After Dual-Controlled vs Volume-Controlled Ventilation in Lung SurgeryThe Annals of Thoracic SurgeryPreviewOne-lung ventilation for thoracic surgery represents a challenge due to the risk for hypoxemia and barotrauma. Dual-controlled ventilation (ie, pressure-regulated volume control [PRVC]) may confer improved lung mechanics compared with conventional ventilation (volume-controlled ventilation [VCV]). Our objective was to determine the association between ventilatory mode and pulmonary outcomes after lung resection surgery. Full-Text PDF

Postoperative Hypoxemia After Dual-Controlled vs Volume-Controlled Ventilation in Lung Surgery

BackgroundOne-lung ventilation for thoracic surgery represents a challenge due to the risk for hypoxemia and barotrauma. Dual-controlled ventilation (ie, pressure-regulated volume control [PRVC]) may confer improved lung mechanics compared with conventional ventilation (volume-controlled ventilation [VCV]). Our objective was to determine the association between ventilatory mode and pulmonary outcomes after lung resection surgery. MethodsA historical cohort (2016-2021) of patients undergoing lung resection surgery was used to identify cases performed with PRVC ventilation (intervention) vs VCV (conventional). Both groups were matched in a 1:1 fashion using propensity scoring based on preoperative oxygen saturation, chronic obstructive pulmonary disease, intraoperative ventilator settings, and surgical approach. Our primary outcome was postoperative hypoxemia (oxygen saturation <92% requiring supplemental oxygen longer than 2 hours). Secondary outcomes included respiratory failure, pneumonia, atelectasis, acute respiratory distress syndrome, pleural effusion, and reintubation. Associations were reported using adjusted odds ratios (aOR). ResultsOf 2107 eligible patients (PRVC = 1587 vs VCV = 520), a total of 774 matched pairs were analyzed (PRVC = 387 vs VCV = 387). The overall incidence of postoperative hypoxemia was 35.5% (95% CI 32.2%-39.0%). Hypoxemia was less likely among patients managed with low tidal volumes (≤6 mL/kg per ideal body weight, aOR 0.73, 95% CI 0.57-0.92, P = .008). No significant association was observed between ventilator mode and postoperative hypoxemia (33.3% in PRVC vs 37.7% in VCV; aOR 0.93, 95% CI 0.71-1.23, P = .627) or secondary pulmonary complications (3.9% in PRVC vs 3.4% in VCV; aOR 0.96, 95% CI 0.47-1.97, P = .909). ConclusionsDual-controlled ventilation was not associated with improved pulmonary outcomes compared with conventional ventilation in lung resection surgery.

Impact of Minimizing Asynchronies in Mechanical Ventilation on Patient’s Outcome in Pediatric Intensive Care Unit

Background: Patients-ventilator asynchrony defined as a mismatch between the patient’s respiratory effort and the ventilator delivered breaths and it is common in clinical practice. Patient ventilator interaction is a key element in optimizing MV. The change from inspiration to expiration is a crucial point in the mechanically ventilated breaths and is termed cycling, PVA may occur if the flow at which the ventilator cycles to exhalation does not coincide with the termination of neural inspiration. Ideally, the ventilator terminates inspiratory flow in synchrony with the patients neural timing, but frequently the ventilator terminates early or late.&#x0D; Aims: The aim of this study was to detect the prevalence of asynchrony during assisted MV, IT and DT were the two main patterns of asynchrony.&#x0D; Patients and Methods: This prospective study was carried out upon 60 patients from 2 to 180 months, 38 males and 22 females, with spontaneous triggering on MV, admitted to the PICU, Tanta University Hospital.&#x0D; Results: Fortunately, ITI is increased with volume SIMV +PSV compared with pressure SIMV +PSV and PRVC. ITI is a highly significant diagnostic for synchronization. Pressure regulated volume control was better than pressure SIMV+PSV and both were better than volume SIMV +PSV proved by less ITI and increase mortality with ITI ≥10%.&#x0D; Conclusion: Pressure regulated volume control was better than pressure SIMV+PSV and both were better than volume SIMV +PSV proved by less ITI and increase mortality with ITI ≥10%. The patient-ventilator synchrony is crucial in determining the patient comfort, MV duration, and survival ITI is diagnostic for synchronization. ITI, PIP/ITI on 1st day, and SpO2 on 3rd day were significant predictors for synchronization.

Pneumothorax in Critically Ill COVID-19 Patients: Prevalence, Analysis of Risk Factors and Clinical Outcomes.

Previous studies have been conducted to assess pneumothorax. However, few studies were done to assess pneumothorax in COVID-19 patients in the intensive care unit (ICU). Our aim is to describe and analyze the prevalence, clinical characteristics, risk factors, and outcomes of COVID-19 pneumothorax patients in the intensive care unit. We performed a retrospective review of the medical records of 418 patients, who tested positive for COVID-19 by polymerase chain reaction test and required ICU admission in King Fahad Hospital of The University from 02/01/2020 to 01/09/2021. A total number of 36 pneumothorax patients were included in the study. Of 418 patients who were followed up in the intensive care unit as COVID-19 cases, 36 patients developed a pneumothorax (8.61%). The mean age of the patients was 55.6 ± 15.06 years, 23 patients were male, and 13 were female. Seventeen patients were obese, and only one patient was an active smoker. Twenty-four patients had at least one comorbidity; hypertension was the most common. Thirty-two patients were intubated, and the duration of intubation was 23.23 ±15.9 days. The time from intubation to pneumothorax development was 8.8 ± 9.3 days. Six patients were on bilevel positive airway pressure ventilation (BIPAP), 2 patients on continuous positive airway pressure ventilation (CPAP), 3 patients on High-Flow Nasal Cannula ventilation (HFNC), 9 patients on pressure-control ventilation (PC), and 16 patients on pressure regulated volume control ventilation (PRVC). Of 36 patients, 26 died, and the mortality rate was 72.2%. Our study showed that risk factors of pneumothorax occurrence in COVID-19 critically ill patients include male patients, hypertension, diabetes mellitus, endotracheal intubation and mechanical ventilation. More efforts should be made to determine the risk factors and assess the outcomes of those patients to develop preventive measures and management guidelines.

Mechanical power in AVM-2 versus conventional ventilation modes in various ARDS lung models. Bench study

Introduction Mechanical power has been linked to ventilator induced lung injury and mortality in acute respiratory distress syndrome (ARDS). Adaptive Ventilator Mode-2 is a closed-loop pressure-controlled mode with an optimal targeting scheme based on the inspiratory power equation that adjusts the respiratory rate and tidal volume to achieve a target minute ventilation. Conceptually, this mode should reduce the mechanical power delivered to the patients and thus reduce the incidence of ventilator induced lung injury. Methods A bench study using a lung simulator was conducted. We constructed three passive single compartment ARDS models (Mild, Moderate, Severe) with compliance of 40, 30, 20 ml/cmH2O respectively, and resistance of 10 cmH2O/L/s, with IBW 70 kg. We compared three different ventilator modes: AVM-2, Pressure Regulated Volume Control (PRVC), and Volume Controlled Ventilation (VCV) in six different scenarios: 3 levels of minute ventilation 7, 10.5, and 14 Lit/min (Experiment 1, 2, and 3 respectively), each with 3 different PEEP levels 10, 15, and 20 cmH2O (Experiment A, B, and C respectively) termed 1A, 1B, 1C, 2A, 2B, 2C, 3A, 3B, 3C respectively for a total of 81 experiments. The AVM-2 mode automatically selects the optimal tidal volume and respiratory rate per the dialed percent minute ventilation with an I:E ratio of 1:1. In the PRVC and VCV (constant flow) we selected target tidal volume 6ml/kg/IBW (420 ml) and respiratory rate adjusted to match the minute ventilation for the AVM-2 mode. I:E ratio was kept 1:2. The mechanical power delivered by the ventilator for each mode was computed and compared between the three modes in each experiment. Statistical analysis was done using Kruskal-Wallis test to analyze the difference between the three modes, post HOC Tukey test was used to analyze the difference between each mode where P &lt; 0.05 was considered statistically significant. The Power Compliance Index was calculated and compared in each experiment. Multiple regression analysis was performed in each mode to test the correlation of the variables of mechanical power to the total calculated power. Results There were statistically significant differences (P &lt; 0.001) between all the three modes regarding the ventilator delivered mechanical power. AVM-2 mode delivered significantly less mechanical power than VCV which in turn was less than PRVC. The Power Compliance index was also significantly lower (P &lt; 0.01) in the AVM-2 mode compared to the other conventional modes. Multiple regression analysis indicated that in AVM-2 mode, the driving pressure (P = 0.004), tidal volume (P &lt; 0.001), respiratory rate (P = 0.011) and PEEP (P &lt; 0.001) were significant predictors in the model. In the VCV mode, the respiratory rate (P 0&lt; 0.001) and PEEP (P &lt; 0.001) were significant predictors, but the driving pressure was a non-significant predictor (P = 0.08). In PRVC mode, the respiratory rate (P &lt; 0.001), PEEP (P &lt; 0.001) and driving pressure (P &lt; 0.001) were significant predictors. Conclusion AVM2 mode delivered less mechanical power compared to two conventional modes using low tidal volume in an ARDS lung model with different severities. This might translate to the reduction of the incidence of ventilator induced lung injury. Results need to be validated in clinical studies.

Flow-controlled ventilation maintains gas exchange and lung aeration in a pediatric model of healthy and injured lungs: A randomized cross-over experimental study.

Flow-controlled ventilation (FCV) is characterized by a constant flow to generate active inspiration and expiration. While the benefit of FCV on gas exchange has been demonstrated in preclinical and clinical studies with adults, the value of this modality for a pediatric population remains unknown. Thus, we aimed at observing the effects of FCV as compared to pressure-regulated volume control (PRVC) ventilation on lung mechanics, gas exchange and lung aeration before and after surfactant depletion in a pediatric model. Ten anesthetized piglets (10.4 ± 0.2 kg) were randomly assigned to start 1-h ventilation with FCV or PRVC before switching the ventilation modes for another hour. This sequence was repeated after inducing lung injury by bronchoalveolar lavage and injurious ventilation. The primary outcome was respiratory tissue elastance. Secondary outcomes included oxygenation index (PaO2/FiO2), PaCO2, intrapulmonary shunt (Qs/Qt), airway resistance, respiratory tissue damping, end-expiratory lung volume, lung clearance index and lung aeration by chest electrical impedance tomography. Measurements were performed at the end of each protocol stage. Ventilation modality had no effect on any respiratory mechanical parameter. Adequate gas exchange was provided by FCV, similar to PRVC, with sufficient CO2 elimination both in healthy and surfactant-depleted lungs (39.46 ± 7.2 mmHg and 46.2 ± 11.4 mmHg for FCV; 36.0 ± 4.1 and 39.5 ± 4.9 mmHg, for PRVC, respectively). Somewhat lower PaO2/FiO2 and higher Qs/Qt were observed in healthy and surfactant depleted lungs during FCV compared to PRVC (p < 0.05, for all). Compared to PRVC, lung aeration was significantly elevated, particularly in the ventral dependent zones during FCV (p < 0.05), but this difference was not evidenced in injured lungs. Somewhat lower oxygenation and higher shunt ratio was observed during FCV, nevertheless lung aeration improved and adequate gas exchange was ensured. Therefore, in the absence of major differences in respiratory mechanics and lung volumes, FCV may be considered as an alternative in ventilation therapy of pediatric patients with healthy and injured lungs.

Mechanical power in AVM-2 versus conventional ventilation modes in a normal lung model: A bench study

Introduction Recent studies suggested that the energy delivered by the mechanical ventilator to the lungs termed the mechanical power can induce and increase the risks of ventilator induced lung injury. The components of the mechanical power include the variables delivered by the ventilator: tidal volume, respiratory rate, inspiratory flow, airway pressure. Adaptive Ventilator Mode-2 (AVM-2) is a pressure-controlled mode with an optimal targeting scheme based on the inspiratory power equation that adjusts the respiratory rate and tidal volume to achieve a target minute ventilation. This mode conceptually should reduce the mechanical power delivered to the patients and thus reduce the incidence of ventilator induced lung injury. Methodology A bench study using a lung simulator (TTL, Michigan Instruments, Michigan, USA) was conducted. We constructed a passive single compartment normal respiratory mechanics model with compliance of 50 ml/cmH2O, and resistance of 10 cmH2O/L/s, with IBW 70 kg. We compared three different ventilator modes: Adaptive Ventilation Mode-2 (AVM-2), Pressure Regulated Volume Control (PRVC), and Volume Controlled Ventilation (VCV) in four different scenarios: 2 levels of minute ventilation 7 and 10.5 Lit/min (Experiment 1 and 2 respectively), each with 2 different PEEP levels 5 and 10 cmH2O (Experiment A and B respectively) termed Experiments 1A, 1B, 2A, and 2B respectively. The AVM-2 mode automatically selects the optimal tidal volume, and respiratory rate per the dialed percent minute ventilation with an I:E ratio of 1:1. In the PRVC, VCV we selected target tidal volume 6ml/kg/IBW (420 ml), and respiratory rate adjusted to match the minute ventilation for the AVM-2 mode. I:E ratio was kept 1:2 to avoid intrinsic PEEP. The study was conducted using a bellavista™ 1000 e Ventilator (Vyaire Medical, Illinois, USA). The mechanical power delivered by the ventilator for each mode was computed and compared between the three modes in each experiment. Statistical analysis was done using Kruskal-Wallis test to analyze the difference between the three modes, post HOC Tukey test was used to analyze the difference between each mode with the confidence intervals, P &lt; 0.05 was considered statistically significant. Results There were statistically significant differences between all the three modes regarding the ventilator delivered mechanical power. The AVM-2 mode delivered significantly less mechanical power than VCV which in turn was less than PRVC. Experiment 1A: AVM-2 8.76 土 0.05, VCV 9.78 土 0.04, PRVC 10.82 土 0.08, P &lt; 0.001 Experiment 1B: AVM-2 11.27 ± 0.09 VCV 12.81 ± 0.05, PRVC 13.88 ± 0.06, P &lt; 0.001. Experiment 2A: AVM-2 14.76 ± 0.05, VCV 15.79 ± 0.05, PRVC 18.29 ± 0.07, P &lt; 0.001, Experiment 2B: AVM-2 18.76 ± 0.04, VCV 20.56 ± 0.04, PRVC 21.17 土 0.03, P &lt; 0.001. Discussion AVM2 mode delivered less mechanical power compared to two conventional modes using low tidal volume in a normal lung model. This might reduce the incidence of ventilator induced lung injury. Results need to be validated in more clinical studies.

Pressure-Regulated Volume Control and Pressure-Control Ventilation Modes in Pediatric Acute Respiratory Failure

ObjectiveThe objective of this study is to present our experience using the pressure-regulated volume control and the pressure-control ventilation modes in children.MethodsPatients with acute respiratory failure ventilated with pressure-regulated volume control or pressure-control modes were retrospectively evaluated. The patient’s ventilation parameters (of the first 7 days of ventilation or of the whole ventilation period, if the patient had been ventilated less than 7 days), SpO2, blood gases, and demographic data were collected from the pediatric intensive care unit database. ResultsSixty-one patients (median age 12 [4.8-36.4] months) were enrolled in the study. The pressure-control ventilation mode was used on 40 patients (65.6%) and the pressure-regulated volume-control mode was used on 21 (34.4%) patients. Twenty-eight patients (45.9%) had hypoxemic respiratory failure and 44 (72.1%) had hypercapnic respiratory failure. The median positive end-expiratory pressure was higher in pressure-control ventilation mode (5.4 [4.2-6.3] cmH2O) than the pressure-regulated volume-control mode (4.05 [3.68-4.41] H2O, P < .001). Pressure-control mode was used more frequently in hypoxemic cases but both modes were used equally in hypercapnic cases. Hypoxic respiratory failure (yes/no), odds ratio: 3.9 (95% CI 1.2-12.3, P = .02), Ph (nadir), odds ratio: 0.004 (95% CI 0.000-0.275, P = .01), and base excess, odds ratio: 0.88 (95% CI 0.79-0.98, P = .02) were associated with intensive care mortality.ConclusionsAlthough the pressure-control ventilation mode was preferred more frequently in hypoxemic respiratory failure, there was no significant difference between the 2 respiratory modes in terms of length of pediatric intensive care unit stay, MV duration, and mortality. The pressure-regulated volume-control mode seems to be a safer option for physicians who do not have enough experience in using pressure-control ventilation mode.

Agreement Between Peak Inspiratory Pressure in Decelerating-Flow Ventilation and Plateau Pressure in Square-Flow Ventilation in Pediatric Acute Respiratory Distress Syndrome.

Acute respiratory distress syndrome guidelines suggest limiting plateau pressures to 28-30 cm H2O. Plateau pressure is most accurately measured in square-flow modes, such as volume control. In children, decelerating-flow modes, such as pressure-regulated volume control and pressure control, are more common. Consequently, plateau pressures are rarely obtained, and pressure limits are instead provided for peak inspiratory pressure. The degree to which peak inspiratory pressure in decelerating-flow overestimates plateau pressure is unknown. Therefore, we assessed the correlation and accuracy of peak inspiratory pressure in decelerating-flow ventilation for approximating plateau pressure during square-flow ventilation. Prospective, observational study. Tertiary, academic PICU. Fifty-two intubated children with acute respiratory distress syndrome enrolled between January 2020 and May 2021. Measurement of peak inspiratory pressure in decelerating-flow ventilation and plateau pressure after transition to square-flow ventilation. Peak inspiratory pressure in decelerating-flow was highly correlated (r2 = 0.99; p < 0.001) with plateau pressure in square-flow. Peak inspiratory pressure was 1.0 ± 0.6 cm H2O higher than plateau pressure, with 96% of values within 2 cm H2O. The single outlier had coexistent asthma and inspiratory flows that did not reach zero. Peak inspiratory pressure measured during decelerating-flow ventilation may be an adequate surrogate of plateau pressure in pediatric acute respiratory distress syndrome when inspiratory flow approaches zero. Practitioners should be aware that peak inspiratory pressures in decelerating-flow may not be substantially higher than plateau pressures.

Nephroblastoma cavoatrial tumor thrombus-A challenge to anesthesiologist.

Nephroblastoma cavoatrial tumor thrombus-A challenge to anesthesiologist.

Empirical evidence for safety of mechanical ventilation during simulated cardiopulmonary resuscitation on a physical model.

Cardiac arrest is a critical event requiring adequate and timely response in order to increase a patient's chance of survival. In patients mechanically ventilated with advanced airways, cardiopulmonary resuscitation (CPR) maneuver may be simplified by keeping the ventilator on. This work assessed the response of an intensive care mechanical ventilator to CPR using a patient manikin ventilated in three conventional modes. Volume-controlled (VCV), pressure-controlled (PCV) and pressure regulated volume-controlled (PRVC) ventilation were applied in a thorax physical model, with or without chest compressions. The mechanical ventilator was set with inspiratory time of 1.0 s, ventilation rate of 10 breaths/min, positive end-expiratory pressure of 0 cmH2O, FiO2 of 1.0, target tidal volume of 600 mL and trigger level of -20 cmH2O. Airway opening pressure and ventilatory flow signals were continuously recorded. Chest compression resulted in increased airway peak pressure in all ventilation modes (p < 0.001), especially with VCV (137% in VCV, 83% in PCV, 80% in PRVC). However, these pressures were limited to levels similar to release valves in manual resuscitators (~60 cmH2O). In pressure-controlled modes tidal/min volumes decreased (PRVC = 11%, p = 0.027 and PCV = 12%, p < 0.001), while still within the variability observed during bag-valve-mask ventilation. During VCV, variation in tidal/min volumes were not significant (p = 0.140). Respiratory rate did not change with chest compression. Volume and pressure ventilation modes responded differently to chest compressions. Yet, variation in delivered volume and the measured peak pressures were within the reported for the standard bag-valve-mask system.

SARS-COV-2-RELATED PNEUMOMEDIASTINUM: A RARE PRESENTATION OF AN EQUALLY RARE COMPLICATION

TOPIC: Critical Care TYPE: Fellow Case Reports INTRODUCTION: Pneumomediastinum is a rare entity in viral pneumonias. Only about 1% of patients in the ARDSNet trials developed pneumomediastinum as an early complication in the first four days of mechanical ventilation. With SARS-CoV-1, there were reports of late development of barotrauma complications, but there are very few case reports of pneumomediastinum in the current pandemic. We present a case of a tension pneumomediastinum and pneumoperitoneum as a complication of SARS-CoV-2. CASE PRESENTATION: An 86-year-old female was hospitalized for respiratory failure secondary to COVID-19. She was treated and discharged to a nursing facility requiring supplemental oxygen. Two days later, she developed worsening respiratory failure requiring intubation and mechanical ventilation with pressure-regulated volume control mode. CT imaging on admission revealed only viral pneumonia changes. Despite open lung ventilation strategy, she required plateau pressures of 32cmH20 to maintain adequate gas exchange. Hospital day 10, her respiratory failure worsened with increased plateau pressures of 40cmH20 despite no changes in her ventilator settings. She required paralysis and proning at that time with no changes on chest x-ray and no abnormalities were appreciated on exam other than developing ventilator dyssynchrony. She deteriorated further on hospital day 15 with development of shock and chest x-ray demonstrating possible free air in the mediastinum and abdomen. CT confirmed massive amounts of intraperitoneal, retroperitoneal, and mediastinal air without pneumothorax. Given her poor prognosis, she was transitioned to comfort measures and expired. DISCUSSION: COVID-19-related pneumomediastinum is thought to develop from diffuse alveolar injury and fibrosis leading to increased alveolar pressures, which ultimately rupture. Barotrauma from mechanical ventilation exacerbates this. Patients may be asymptomatic or they may have signs of tachycardia, tachypnea, and/or subcutaneous emphysema with upper chest and neck swelling. Tension pneumomediastinum is an exceedingly rare but life threatening development in critically ill patients. The development of pneumomediastinum related to SARS-CoV-2 seems to occur later in the disease course when compared to ARDSNet trials, however this may be similar to reports in SARS-CoV-1. CONCLUSIONS: Despite the rare occurrence of pneumomediastinum in viral pneumonia, providers should be aware of this potential late complication in SARS-CoV-2 and take measures for prevention and early recognition. Without adjusting treatment, tension pneumomediastinum may develop and lead to a significant increase in mortality. REFERENCE #1: Chu CM, et al. Spontaneous pneumomediastinum in patients with severe acute respiratory syndrome. European Respiratory Journal 2004 23: 802-804;DOI: 10.1183/09031936.04.00096404 REFERENCE #2: Mart M, et al. Pneumomediastinum in Acute Respiratory Distress Syndrome from COVID-19. Am J Respir Crit Care Med Vol 203, Iss 2, pp 237–238. DOI: 10.1164/rccm.202008-3376IM REFERENCE #3: Clancy DJ, et al. Tension pneumomediastinum: a literal form of chest tightness. J Intensive Care Soc 2017;18(1): 52–56. DISCLOSURES: No relevant relationships by Rayan Ihle, source=Web Response No relevant relationships by Mark Radow, source=Web Response

Сравнение влияния разных режимов искусственной вентиляции легких на церебральную перфузию у новорожденных с гипоксически-ишемической энцефалопатией

Актуальность. На сегодняшний день нет опубликованных результатов крупных рандомизированных контролируемых исследований, которые сравнивали бы дифференцированное влияние различных режимов искусственной вентиляции легких на состояние церебральной перфузии у новорожденных с гипоксически-ишемической энцефалопатией (ГИЭ). Перспективным является применение нового режима вентиляции Neurally Adjusted Ventilatory Assist (NAVA), который уже доказал свои преимущества у недоношенных младенцев. Цель исследования: сравнить влияние Neurally Adjusted Ventilatory Assist и других режимов искусственной вентиляции легких на состояние мозгового кровотока в остром периоде ГИЭ у доношенных новорожденных. Материалы и методы. В исследование включено 205 доношенных новорожденных с гипоксически-ишемической энцефалопатией по Sarnat II–III ст. в сроке ≤ 72 часов после родов. Младенцы были рандомизированы на исследуемую группу с применением NAVA (n = 16) и группу контроля (n = 189), в которую вошли такие режимы вентиляции, как PC, SIMV/PSV и PRVC. Проведен мультивариантный дисперсионный анализ влияния NAVA и других режимов вентиляции на состояние церебральной перфузии в остром периоде неонатальной гипоксически-ишемической энцефалопатии. Результаты. На третий день лечения в конце периода терапевтической гипотермии и начала согревания получено достоверное различие между группами в отношении допплеровского индекса мозгового кровотока RI (0,70 [0,67–0,74] в группе NAVA и 0,66 [0,58–0,72] в группе контроля, р = 0,021) и пульсационного индекса РІ (1,3 [1,2–1,5] в группе NAVA и 1,2 [1,0–1,40] в группе контроля, р = 0,032). Также результаты теста ANOVA подтвердили, что по сравнению с другими режимами вентиляции NAVA имел статистически достоверное положительное влияние на 2-й и 3-й день наблюдения как на величину RI (р = 0,009), так и на РІ (р = 0,012). Выводы. Режим вентиляции Neurally Adjusted Ventilatory Assist продемонстрировал положительное влияние на индексы церебральной перфузии у доношенных новорожденных в остром периоде ГИЭ по сравнению с традиционными режимами PC, SIMV/PSV и PRVC.

Particle flow rate from the airways as fingerprint diagnostics in mechanical ventilation in the intensive care unit: a randomised controlled study.

IntroductionMechanical ventilation can be monitored by analysing particles in exhaled air as measured by particle flow rate (PFR). This could be a potential method of detecting ventilator-induced lung injury (VILI) before changes in conventional parameters can be detected. The aim of this study was to investigate PFR during different ventilation modes in patients without lung pathology.MethodA prospective study was conducted on patients on mechanical ventilation in the cardiothoracic intensive care unit (ICU). A PExA 2.0 device was connected to the expiratory limb on the ventilator for continuous measurement of PFR in 30 patients randomised to either volume-controlled ventilation (VCV) or pressure-controlled ventilation (PCV) for 30 min including a recruitment manoeuvre. PFR measurements were continued as the patients were transitioned to pressure-regulated volume control (PRVC) and then pressure support ventilation (PSV) until extubation.ResultsPRVC resulted in significantly lower PFR, while those on PSV had the highest PFR. The distribution of particles differed significantly between the different ventilation modes.ConclusionsMeasuring PFR is safe after cardiac surgery in the ICU and may constitute a novel method of continuously monitoring the small airways in real time. A low PFR during mechanical ventilation may correlate to a gentle ventilation strategy. PFR increases as the patient transitions from controlled mechanical ventilation to autonomous breathing, which most likely occurs as recruitment by the diaphragm opens up more distal airways. Different ventilation modes resulted in unique particle patterns and could be used as a fingerprint for the different ventilation modes.