Pressure-regulated Volume Control Ventilation Research Articles

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.

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.

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.

Utility and safety of flexible fiberoptic bronchoscopy in mechanically ventilated children in pediatric intensive care unit.

To study the utility, safety, and effects of flexible fiberoptic bronchoscopy (FFB) on oxygenation status, ventilation parameters, and hemodynamics in mechanically ventilated children. Retrospective study. Children aged >1 month to 18 years suffering from critical medical and surgical diseases. First bronchoscopy data of 131 patients wereanalyzed. Indication, FFB findings, the microbiological yield from bronchoalveolar lavage, and medical and surgical interventions based on FFB results were recorded. Hemodynamic and ventilation parameters before, during, and 3 h after FFB were also captured. The majority of bronchoscopies were done for diagnostic purposes with a positivity rate of 90.8%. Retained mucopurulent secretion in the airways was the commonest finding in 60 patients. A cause for weaning or extubation failure could be identified in 83.3%. Post-FFB radiological resolution of atelectasis was seen in 34/59 (57.6%; p-value: 0.001) chest radiographs. Forty-sevenmedical and 25 surgical interventions were done depending on FFB and BAL findings. There was a significant drop in oxygenation parameters and a rise in heart rate during FFB (p-value:<0.0001). The peak inspiratory pressure, positive end-expiratory pressure, and mean airway pressure increased significantly during bronchoscopy (p value:<.0001) while patients were on pressure-regulated volume-controlled ventilation. All these changes reversed to pre-FFB levels. There were minor procedure-related complications. FFB was an important diagnostic and therapeutic tool for mechanically ventilated children and the results helped planinterventions. It was a safe procedure with transient reversible cardiopulmonary alterations.

Nephroblastoma cavoatrial tumor thrombus-A challenge to anesthesiologist.

Nephroblastoma cavoatrial tumor thrombus-A challenge to anesthesiologist.

Mechanical ventilation in Spain, 1998-2016: Epidemiology and outcomes.

To evaluate changes in the epidemiology of mechanical ventilation in Spain from 1998 to 2016. A post hoc analysis of four cohort studies was carried out. A total of 138 Spanish ICUs. A sample of 4293 patients requiring invasive mechanical ventilation for more than 12h or noninvasive ventilation for more than 1h. None. Demographic variables, reason for mechanical ventilation, variables related to ventilatory support (ventilation mode, tidal volume, PEEP, airway pressures), complications during mechanical ventilation, duration of mechanical ventilation, ICU stay and ICU mortality. There was an increase in severity (SAPSII: 43 points in 1998 vs. 47 points in 2016), changes in the reason for mechanical ventilation (decrease in chronic obstructive pulmonary disease and acute respiratory failure secondary to trauma, and increase in neurological disease and post-cardiac arrest). There was an increase in noninvasive mechanical ventilation as the first mode of ventilatory support (p<0.001). Volume control ventilation was the most commonly used mode, with increased support pressure and pressure-regulated volume-controlled ventilation. A decrease in tidal volume was observed (9ml/kg actual b.w. in 1998 and 6.6ml/kg in 2016; p<0.001) as well as an increase in PEEP (3cmH2O in 1998 and 6cmH2O in 2016; p<0.001). In-ICU mortality decreased (34% in 1998 and 27% in 2016; p<0.001), without geographical variability (median OR 1.43; p=0.258). A significant decrease in mortality was observed in patients ventilated in Spanish ICUs. These changes in mortality could be related to modifications in ventilation strategy to minimize ventilator-induced lung injury.

Mechanical ventilation in Spain, 1998–2016: Epidemiology and outcomes

PurposeTo evaluate changes in the epidemiology of mechanical ventilation in Spain from 1998 to 2016. DesignA post hoc analysis of four cohort studies was carried out. SettingA total of 138 Spanish ICUs. PatientsA sample of 4293 patients requiring invasive mechanical ventilation for more than 12 h or noninvasive ventilation for more than one hour. InterventionsNone. Variables of interestDemographic variables, reason for mechanical ventilation, variables related to ventilatory support (ventilation mode, tidal volume, PEEP, airway pressures), complications during mechanical ventilation, duration of mechanical ventilation, ICU stay and ICU mortality. ResultsThere was an increase in severity (SAPS II 43 points in 1998 vs. 47 points in 2016), changes in the reason for mechanical ventilation (decrease in chronic obstructive pulmonary disease and acute respiratory failure secondary to trauma, and increase in neurological disease and post-cardiac arrest). There was an increase in noninvasive mechanical ventilation as the first mode of ventilatory support (p < 0.001). Volume control ventilation was the most commonly used mode, with increased support pressure and pressure-regulated volume-controlled ventilation. A decrease in tidal volume was observed (9 ml/kg actual b.w. in 1998 and 6.6 ml/kg in 2016; p < 0.001) as well as an increase in PEEP (3 cmH2O in 1998 and 6 cmH2O in 2016; p < 0.001). In-ICU mortality decreased (34% in 1998 and 27% in 2016; p < 0.001), without geographical variability (median OR 1.43; p = 0.258). ConclusionsA significant decrease in mortality was observed in patients ventilated in Spanish ICUs. These changes in mortality could be related to modifications in ventilation strategy to minimize ventilator-induced lung injury.

Advanced mechanical ventilation modes: design and computer simulations

In this paper, three different advanced mechanical ventilation modes, pressure regulated volume control ventilation (PRVC), proportional assist ventilation (PAV), and adaptive support ventilation (ASV) are designed and simulated on the computer via MATLAB/Simulink. In the algorithms of advanced ventilation modes, a closed-loop control structure is used and recursive least squares method is considered for the estimation of respiratory mechanics. The designed algorithms are then applied to the human respiratory system model for the active and/or passive patient cases. Simulation results show that such algorithms can be designed and simulated on the computer successfully. In addition, the simulation environment helps us to understand the working principles of the advanced modes and to see the results such as ventilator waveforms, the effect of the parameter changes. Moreover, it also allows us to improve and test the algorithms and strategies quickly and efficiently.

AN UNUSUAL CAUSE OF AIRWAY OBSTRUCTION WITH A NOVEL MANAGEMENT MODALITY

SESSION TITLE: Wednesday Fellows Case Report Posters SESSION TYPE: Fellow Case Report Posters PRESENTED ON: 10/23/2019 09:45 AM - 10:45 AM INTRODUCTION: Tracheostomy is one of the most common procedures performed in intensive care setting as part of modern airway management. It is one of the oldest surgical procedures known to man and was described in Egyptian artifacts in 3600 BC. Complications can be classified into intra-operative, early and late post-operative complications. Granulation tissue formation is one of the known yet sometimes overlooked complications. We present a case of granulation tissue formation at the distal end of tracheostomy tube (TT) causing almost complete obstruction of airway that was successfully managed using Argon Plasma Coagulation (APC). CASE PRESENTATION: A 52-year-old female with a past medical history of ventilator-dependent chronic respiratory failure secondary to kyphoscoliosis was brought in to our emergency department from the nursing facility where she resides for respiratory distress. Patient has a 7 mm non-fenestrated, Cuffed, single lumen TT placed 2 years prior to her presentation. On admission, Temperature was 36.7, heart rate 100 beats/minute, blood pressure 100/60 mmHg, respiratory rate 24 breaths/minute and pulse oximetry of 94% on pressure-regulated volume control ventilation with 60% FiO2. She was noted to have elevated peak airway pressure of 55 cm H2O with plateau pressure of 15 cm H2O on the ventilator. Patient was awake and able to communicate however appeared to be in moderate respiratory distress with reduced air entry bilaterally on auscultation of her chest. The rest of her physical examination was unremarkable. Urgent flexible fiberoptic bronchoscopy (FFB) showed a soft tissue mass fungating from the trachea and almost completely occluding the distal end of the tracheostomy tube. The bronchoscope was advanced through a small laminal opening in the granulation tissue. Distal airway was patent with no lesions or secretions noted. The granulation tissue was excised using APC and TT was exchanged to a 6-mm extended-length tube to bypass the remaining obstruction. Patient had significant improvement of her symptoms and was transferred back to the nursing facility. DISCUSSION: Granulation tissue formation post tracheostomy can develop from repetitive irritation leading to mucosal metaplasia and as it matures, it becomes fibrous and if large enough, may impose a risk for airway obstruction. Management modalities range from topical medications to surgical interventions. APC uses high frequency electric current for thermal coagulation and devitalization of tissue. It gives a controlled limited penetration of tissue with good control of bleeding. CONCLUSIONS: Given that granulation can recur, patients with this condition should undergo surveillance imaging and bronchoscopy. We report this case so that clinicians would keep a high index of suspicion for post-tracheostomy granulation tissue formation and to emphasize the role of FFB with APC in diagnosing and managing such complications. Reference #1: Bhatia G, Abraham V, Louis L. Tracheal granulation as a cause of unrecognized airway narrowing. J Anaesthesiol Clin Pharmacol. 2012;28(2):235-8. Reference #2: Sato M., Terada Y., Nakagawa T., Li M., Wada H. Successful use of argon plasma coagulation and tranilast to treat granulation tissue obstructing the airway after tracheal anastomosis. (2000) Chest, 118 (6) , pp. 1829-1831. Reference #3: Rasband-Lindquist, Allison; Sale, Keith. A novel approach to excision of distal tracheal granulation tissue in tracheostomy patients with difficult anatomy. ENT: Ear, Nose & Throat Journal . Oct/Nov2016, Vol. 95 Issue 10/11, p454-459. 5p DISCLOSURES: No relevant relationships by Abdullah Al Twal, source=Web Response No relevant relationships by Delyse Garg, source=Web Response No relevant relationships by Marc Lindner, source=Web Response No relevant relationships by Christina Migliore Patel, source=Web Response No relevant relationships by Habib Nazir, source=Web Response No relevant relationships by Pratik Patel, source=Web Response

Comparison of pressure-regulated volume control ventilation and pressure control ventilation in patients with abdominal compartment syndrome.

Mechanical ventilation support is commonly required in abdominal compartment syndrome (ACS). In the present study, pressure-regulated volume control ventilation (PRVCV) was compared to pressure control ventilation (PCV) in patients with ACS. The prospective study included 40 patients with ACS who were randomized into the PCV or PRVCV groups and subjected to the different modes of ventilation. After 6 h of ventilation, arterial blood gas, respiratory mechanics and hemodynamics parameters, as well as the intra-abdominal pressure (IAP) and Sequential Organ Failure Assessment (SOFA) scores were calculated. Compared to the PCV mode, mechanical ventilation with PRVCV lead to a significant decrease in the partial pressure of carbon dioxide, the peak inspiratory pressure, the mean inspiratory pressure, the central venous pressure, the heart rate and the extravascular lung water index. In addition, a marked improvement in pH, partial pressure of oxygen, oxygenation index and pulmonary static compliance was noted. However, no significant differences in airway resistance, mean arterial pressure, or IAP and SOFA scores were obtained. In conclusion, the PRVCV mode is better than the PCV mode in ventilation patients with ACS, and should therefore be used as a lung protective strategy. The present study was registered at Chictr.org (no. ChiCTR1800016869).

Pressure-regulated volume control ventilation as a means of improving lung-protective ventilation.

Pressure-regulated volume control ventilation as a means of improving lung-protective ventilation.

Application of PRVC in laparoscopic surgery

Objective: To discuss the clinical significance and value of PRVC by monitoring, comparing and studying pressure control (PC), volume control (VC) and pressure-regulated volume control (PRVC) ventilation modes during pneumoperitoneum. Methods: Ninety patients with laparoscopic cholecystectomy were randomly and equally divided into 3 groups (PC group, VC group and PRVC group). Esophageal pressure (PES), mean airway pressure (PAWM), peak airway pressure (PAP), arterial blood carbon dioxide partial pressure (PaCO 2 ), end-tidal carbon dioxide concentration in the expired air (ETCO 2 ), tidal volume (TV), mean arterial pressure (MAP) and heart rate (HR) were not only detected before pneumoperitoneum, but also in 5, 10, 15 and 20 minutes after pneumoperitoneum. Results: PES after pneumoperitoneum in VC mode was obviously higher than that in PC and PRVC groups. In 10 minutes after pneumoperitoneum, levels of PaCO 2 and ETCO 2 became increased obviously in PC and VC groups ( p < .05); levels of PaCO 2 and ETCO 2 were not only increased in PC group, but also the level of TV after pneumoperitoneum in PC group was significantly lower than that in the other two groups ( p < .05). Levels of PaCO 2 and ETCO 2 were increased in PC and VC groups after pneumoperitoneum, along with the increase of MAP and HR ( p < .05). After pneumoperitoneum, levels of MAP and HR in PRVC group were significantly lower than those in PC and VC groups ( p < .05). Conclusions: PRVC mode can effectively reduce the pneumoperitoneum-induced increase of PAWM, PAP and PES without the unusual increase of PaCO 2 and ETCO 2 during surgery, so as to guarantee the stability of vital signs in perioperative patients.

Synchronized mechanical ventilation for respiratory support in newborn infants.

During synchronised mechanical ventilation, positive airway pressure and spontaneous inspiration coincide. If synchronous ventilation is provoked, adequate gas exchange should be achieved at lower peak airway pressures, potentially reducing baro/volutrauma, air leak and bronchopulmonary dysplasia. Synchronous ventilation can potentially be achieved by manipulation of rate and inspiratory time during conventional ventilation and employment of patient-triggered ventilation. To compare the efficacy of:(i) synchronised mechanical ventilation, delivered as high-frequency positive pressure ventilation (HFPPV) or patient-triggered ventilation (assist control ventilation (ACV) and synchronous intermittent mandatory ventilation (SIMV)), with conventional ventilation or high-frequency oscillation (HFO);(ii) different types of triggered ventilation (ACV, SIMV, pressure-regulated volume control ventilation (PRVCV), SIMV with pressure support (PS) and pressure support ventilation (PSV)). We used the standard search strategy of the Cochrane Neonatal Review group to search the Cochrane Central Register of Controlled Trials (CENTRAL 2016, Issue 5), MEDLINE via PubMed (1966 to June 5 2016), EMBASE (1980 to June 5 2016), and CINAHL (1982 to June 5 2016). We also searched clinical trials databases, conference proceedings, and the reference lists of retrieved articles for randomised controlled trials and quasi-randomised trials. Randomised or quasi-randomised clinical trials comparing synchronised ventilation delivered as HFPPV to CMV, or ACV/SIMV to CMV or HFO in neonates. Randomised trials comparing different triggered ventilation modes (ACV, SIMV, SIMV plus PS, PRVCV and PSV) in neonates. Data were collected regarding clinical outcomes including mortality, air leaks (pneumothorax or pulmonary interstitial emphysema (PIE)), severe intraventricular haemorrhage (grades 3 and 4), bronchopulmonary dysplasia (BPD) (oxygen dependency beyond 28 days), moderate/severe BPD (oxygen/respiratory support dependency beyond 36 weeks' postmenstrual age (PMA) and duration of weaning/ventilation.Eight comparisons were made: (i) HFPPV versus CMV; (ii) ACV/SIMV versus CMV; (iii) SIMV or SIMV + PS versus HFO; iv) ACV versus SIMV; (v) SIMV plus PS versus SIMV; vi) SIMV versus PRVCV; vii) SIMV vs PSV; viii) ACV versus PSV. Data analysis was conducted using relative risk for categorical outcomes, mean difference for outcomes measured on a continuous scale. Twenty-two studies are included in this review. The meta-analysis demonstrates that HFPPV compared to CMV was associated with a reduction in the risk of air leak (typical relative risk (RR) for pneumothorax was 0.69, 95% confidence interval (CI) 0.51 to 0.93). ACV/SIMV compared to CMV was associated with a shorter duration of ventilation (mean difference (MD) -38.3 hours, 95% CI -53.90 to -22.69). SIMV or SIMV + PS was associated with a greater risk of moderate/severe BPD compared to HFO (RR 1.33, 95% CI 1.07 to 1.65) and a longer duration of mechanical ventilation compared to HFO (MD 1.89 days, 95% CI 1.04 to 2.74).ACV compared to SIMV was associated with a trend to a shorter duration of weaning (MD -42.38 hours, 95% CI -94.35 to 9.60). Neither HFPPV nor triggered ventilation was associated with a significant reduction in the incidence of BPD. There was a non-significant trend towards a lower mortality rate using HFPPV versus CMV and a non-significant trend towards a higher mortality rate using triggered ventilation versus CMV. No disadvantage of HFPPV or triggered ventilation was noted regarding other outcomes. Compared to conventional ventilation, benefit is demonstrated for both HFPPV and triggered ventilation with regard to a reduction in air leak and a shorter duration of ventilation, respectively. In none of the trials was complex respiratory monitoring undertaken and thus it is not possible to conclude that the mechanism of producing those benefits is by provocation of synchronised ventilation. Triggered ventilation in the form of SIMV ± PS resulted in a greater risk of BPD and duration of ventilation compared to HFO. Optimisation of trigger and ventilator design with respect to respiratory diagnosis is encouraged before embarking on further trials. It is essential that newer forms of triggered ventilation are tested in randomised trials that are adequately powered to assess long-term outcomes before they are incorporated into routine clinical practice.

Measurement of pleural pressure swings with a fluid-filled esophageal catheter vs pulmonary artery occlusion pressure

PurposePleural pressure measured with esophageal balloon catheters (Peso) can guide ventilator management and help with the interpretation of hemodynamic measurements, but these catheters are not readily available or easy to use. We tested the utility of an inexpensive, fluid-filled esophageal catheter (Peso) by comparing respiratory-induced changes in pulmonary artery occlusion (Ppao), central venous (CVP), and Peso pressures. MethodsWe studied 30 patients undergoing elective cardiac surgery who had pulmonary artery and esophageal catheters in place. Proper placement was confirmed by chest compression with airway occlusion. Measurements were made during pressure-regulated volume control (VC) and pressure support (PS) ventilation. ResultsThe fluid-filled esophageal catheter provided a high-quality signal. During VC and PS, change in Ppao (∆Ppao) was greater than ∆Peso (bias = −2 mm Hg) indicating an inspiratory increase in cardiac filling. During VC, ∆CVP bias was 0 indicating no change in right heart filling, but during PS, CVP fell less than Peso indicating an inspiratory increase in filling. Peso measurements detected activation of expiratory muscles, development of non–west zone 3 lung conditions during inspiration, and ventilator-triggered inspiratory efforts. ConclusionsA fluid-filled esophageal catheter provides a high-quality, easily accessible, and inexpensive measure of change in pleural pressure and provided insights into patient-ventilator interactions.

Synchronized mechanical ventilation for respiratory support in newborn infants.

During synchronised mechanical ventilation, positive airway pressure and spontaneous inspiration coincide. If synchronous ventilation is provoked, adequate gas exchange should be achieved at lower peak airway pressures, potentially reducing baro/volutrauma, air leak and bronchopulmonary dysplasia. Synchronous ventilation can potentially be achieved by manipulation of rate and inspiratory time during conventional ventilation and employment of patient-triggered ventilation. To compare the efficacy of:(i) synchronised mechanical ventilation, delivered as high-frequency positive pressure ventilation (HFPPV) or patient-triggered ventilation (assist control ventilation (ACV) and synchronous intermittent mandatory ventilation (SIMV)), with conventional ventilation or high-frequency oscillation (HFO);(ii) different types of triggered ventilation (ACV, SIMV, pressure-regulated volume control ventilation (PRVCV), SIMV with pressure support (PS) and pressure support ventilation (PSV)). We used the standard search strategy of the Cochrane Neonatal Review group to search the Cochrane Central Register of Controlled Trials (CENTRAL 2016, Issue 5), MEDLINE via PubMed (1966 to June 5 2016), EMBASE (1980 to June 5 2016), and CINAHL (1982 to June 5 2016). We also searched clinical trials databases, conference proceedings, and the reference lists of retrieved articles for randomised controlled trials and quasi-randomised trials. Randomised or quasi-randomised clinical trials comparing synchronised ventilation delivered as HFPPV to CMV, or ACV/SIMV to CMV or HFO in neonates. Randomised trials comparing different triggered ventilation modes (ACV, SIMV, SIMV plus PS, PRVCV and PSV) in neonates. Data were collected regarding clinical outcomes including mortality, air leaks (pneumothorax or pulmonary interstitial emphysema (PIE)), severe intraventricular haemorrhage (grades 3 and 4), bronchopulmonary dysplasia (BPD) (oxygen dependency beyond 28 days), moderate/severe BPD (oxygen/respiratory support dependency beyond 36 weeks' postmenstrual age (PMA) and duration of weaning/ventilation.Eight comparisons were made: (i) HFPPV versus CMV; (ii) ACV/SIMV versus CMV; (iii) SIMV or SIMV + PS versus HFO; iv) ACV versus SIMV; (v) SIMV plus PS versus SIMV; vi) SIMV versus PRVCV; vii) SIMV vs PSV; viii) ACV versus PSV. Data analysis was conducted using relative risk for categorical outcomes, mean difference for outcomes measured on a continuous scale. Twenty-two studies are included in this review. The meta-analysis demonstrates that HFPPV compared to CMV was associated with a reduction in the risk of air leak (typical relative risk (RR) for pneumothorax was 0.69, 95% confidence interval (CI) 0.51 to 0.93). ACV/SIMV compared to CMV was associated with a shorter duration of ventilation (mean difference (MD) -38.3 hours, 95% CI -53.90 to -22.69). SIMV or SIMV + PS was associated with a greater risk of moderate/severe BPD compared to HFO (RR 1.33, 95% CI 1.07 to 1.65) and a longer duration of mechanical ventilation compared to HFO (MD 1.89 days, 95% CI 1.04 to 2.74).ACV compared to SIMV was associated with a trend to a shorter duration of weaning (MD -42.38 hours, 95% CI -94.35 to 9.60). Neither HFPPV nor triggered ventilation was associated with a significant reduction in the incidence of BPD. There was a non-significant trend towards a lower mortality rate using HFPPV versus CMV and a non-significant trend towards a higher mortality rate using triggered ventilation versus CMV. No disadvantage of HFPPV or triggered ventilation was noted regarding other outcomes. Compared to conventional ventilation, benefit is demonstrated for both HFPPV and triggered ventilation with regard to a reduction in air leak and a shorter duration of ventilation, respectively. In none of the trials was complex respiratory monitoring undertaken and thus it is not possible to conclude that the mechanism of producing those benefits is by provocation of synchronised ventilation. Triggered ventilation in the form of SIMV ± PS resulted in a greater risk of BPD and duration of ventilation compared to HFO. Optimisation of trigger and ventilator design with respect to respiratory diagnosis is encouraged before embarking on further trials. It is essential that newer forms of triggered ventilation are tested in randomised trials that are adequately powered to assess long-term outcomes before they are incorporated into routine clinical practice.

A comparison of synchronized intermittent mandatory ventilation and pressure-regulated volume control ventilation in elderly patients with&amp;nbsp;acute exacerbations of COPD and respiratory failure

BackgroundCOPD is the third leading cause of death worldwide. Acute exacerbations of COPD may cause respiratory failure, requiring intensive care unit admission and mechanical ventilation. Intensive care unit patients with acute exacerbations of COPD requiring mechanical ventilation have higher mortality rates than other hospitalized patients. Although mechanical ventilation is the most effective intervention for these conditions, invasive ventilation techniques have yielded variable effects.ObjectiveWe evaluated pressure-regulated volume control (PRVC) ventilation treatment efficacy and preventive effects on pulmonary barotrauma in elderly COPD patients with respiratory failure.Patients and methodsThirty-nine intubated patients were divided into experimental and control groups and treated with the PRVC and synchronized intermittent mandatory ventilation – volume control methods, respectively. Vital signs, respiratory mechanics, and arterial blood gas analyses were monitored for 2–4 hours and 48 hours.ResultsBoth groups showed rapidly improved pH, partial pressure of oxygen (PaO2), and PaO2 per fraction of inspired O2 levels and lower partial pressure of carbon dioxide (PaCO2) levels. The pH and PaCO2 levels at 2–4 hours were lower and higher, respectively, in the test group than those in the control group (P<0.05 for both); after 48 hours, blood gas analyses showed no statistical difference in any marker (P>0.05). Vital signs during 2–4 hours and 48 hours of treatment showed no statistical difference in either group (P>0.05). The level of peak inspiratory pressure in the experimental group after mechanical ventilation for 2–4 hours and 48 hours was significantly lower than that in the control group (P<0.05), while other variables were not significantly different between groups (P>0.05).ConclusionAmong elderly COPD patients with respiratory failure, application of PRVC resulted in rapid improvement in arterial blood gas analyses while maintaining a low peak inspiratory pressure. PRVC can reduce pulmonary barotrauma risk, making it a safer protective ventilation mode than synchronized intermittent mandatory ventilation – volume control.

Pressure regulated volume controlled ventilation versus synchronized intermittent mandatory ventilation in COPD patients suffering from acute respiratory failure

BackgroundVolume controlled ventilation (VC) allows a set tidal volume to be guaranteed but it causes excessive airway pressures that may lead to barotrauma. Pressure controlled ventilation (PC) limits ventilator-induced lung injury but has a disadvantage of variable tidal volume delivery. Pressure-regulated volume controlled ventilation is a kind of dual-control ventilation that combines the advantages of both volume controlled and pressure controlled ventilation. ObjectiveTo compare the pressure regulated volume controlled ventilation (PRVC) versus traditional synchronized intermittent mandatory ventilation (SIMV) in chronic obstructive pulmonary disease (COPD) patients suffering from acute respiratory failure. Patients and methodsThis prospective study was carried on 30 COPD patients suffering from acute respiratory failure, divided in two groups: group 1 patients were ventilated using the SIMV mode and group 2 patients were ventilated using the PRVC mode. The arterial blood gas (ABG) parameters, ventilation data, complications and prognosis were compared in the two groups. ResultsThe ABG parameters improved better in the PRVC group after 6 and 48h. The peak inspiratory pressure (PIP) values were lower in the PRVC group. There were fewer complications (33% in group 2 versus 86% in group 1). The prognosis was better in PRVC group as 13 patients (86%) were weaned, 1 patient (7%) died and 1 patient (7%) failed to be weaned. On the other hand, 6 patients (40%) were weaned, 3 patients (20%) died and 6 patients (40%) failed to be weaned in the SIMV group. ConclusionThe PRVC mode is better than the volume controlled SIMV mode in ventilating COPD patients with acute exacerbations and type II respiratory failure.

Effect of Tidal Volume and Nebulizer Type and Position on Albuterol Delivery in a Pediatric Model of Mechanical Ventilation.

Optimization of factors affecting aerosol delivery during mechanical ventilation in the pediatric population is important. We hypothesized that increasing the tidal volume (V(T)), using a vibrating mesh nebulizer, and placing the nebulizer at the ventilator would increase lung dose/delivery efficiency. Continuous-output jet and vibrating mesh nebulizers loaded with albuterol (2.5 mg/3 mL) were compared when placed before the Y-piece and at the ventilator. The model consisted of a ventilator operated in pressure-regulated volume control ventilation mode at a breathing frequency of 20 breaths/min, PEEP of 5 cm H2O, FIO2 of 0.4, inspiratory time of 0.75 s, and bias flow of 0.5 L/min with a humidifier (37 ± 1.5°C) and an adult heated-wired circuit. V(T) values of 100, 150, 200, and 300 mL were studied. The circuit was connected in series to a 5.5-mm inner diameter endotracheal tube with a filter (lung dose) interposed between them. Delivery efficiency was calculated as a percentage of the nominal dose captured on the filter. Albuterol content was analyzed by spectrophotometry (276 nm). No differences in lung dose/delivery efficiency were found at different V(T) values for the jet nebulizer (both positions) and the vibrating mesh nebulizer (ventilator). Lung dose/delivery efficiency was higher (P < .02) at a VT of 100 mL compared with the other volumes tested. The vibrating mesh nebulizer had higher lung dose/delivery efficiency compared with the jet nebulizer only when placed before the Y-piece. Moving the nebulizers from before the Y-piece to the ventilator increased lung dose/delivery efficiency for all conditions tested except the vibrating mesh nebulizer at a V(T) of 100 mL (P = .36). Optimization of inhaled drug delivery during pediatric mechanical ventilation should include careful selection of the type of delivery device and its placement in the ventilator circuit. Increasing V(T) during nebulization did not increase lung dose/delivery efficiency.

Congenital lobar emphysema: Intubation and ventilation strategies.

Sir, The case report entitled “congenital lobar emphysema: A modified approach to anesthetic management” by Nandihalli et al.[1] made for interesting reading. Tracheal intubation at the time of anesthetic induction and the subsequent ventilation strategies are the cornerstone of successful anesthetic management of such cases and may influence the outcome. We would like to make certain observations on the described management of this case. In the abstract, they have written that they adopted gentle manual ventilation maintaining the airway pressure before thoracotomy as described by Cote and Payne et al. This fact has been repeated in the discussion section also. In the case report, it has been mentioned that deliberate endobronchial intubation was performed and intermittent positive pressure ventilation (IPPV) was carried out using low tidal volumes (4-6 ml) on pressure regulated volume control mode. Later on they went on to conclude that “if IPPV is necessary, gentle manual ventilation or pressure controlled ventilation with a pressure limit of 20-25 cm of H2O can be carried out until thoracotomy”. To us it is not clear actually which ventilation mode was applied. We would also like to know the names of the breathing circuit and the anesthesia workstation that was used to manage this case because that will give a clue to the method employed. Deliberate endobronchial intubation using a tracheal tube is described in literature. However, some important measures from the safety point of view should be kept in mind. In children, it is suggested to use a tracheal tube 0.5-2.0 mm smaller in diameter than recommended for the particular patient.[2] Their patient was somewhat older at presentation as he was symptom free till the age of 9 months and a tube of 4.5 mm internal diameter was used. Another issue that should be kept in mind with right endobronchial intubation is the possible blockage of the right upper lobe bronchus by the tube. Different ventilation strategies for management of such cases are well known. There is nothing new in their description of endobronchial intubation, gentle manual ventilation or pressure regulated volume controlled ventilation that has been already described in literature.[3] So, it is not clear what modification was employed in their management as suggested by the title of the case report.

Is pressure-regulated volume control mode appropriate for severely obstructed patients?

PurposeManagement of mechanical ventilation in severely obstructed patients remains controversial. Pressure-regulated volume control ventilation (PRVCV) has been suggested to be the best option, as it should ensure a prefixed tidal volume at the lowest peak inspiratory pressure. We sought to determine the accuracy of the delivered volume, compared with the programmed volume, when using PRVCV. Materials and methodsExperimental work performing ventilation simulations using volume control ventilation (VCV), PRVCV, and pressure control ventilation (PCV). Each mode was tested at tidal volumes (TVs) of 200 and 500 mL at both low and high airway resistance. Evita XL and Servo-i ventilators were used. ResultsAt 200 ml TV with high resistance, volume delivered with Evita XL was 165 mL (95% confidence interval, 158-169) in VCV, 117 mL (95% confidence interval, 117-120) in PCV, and 120 (95% confidence interval, 115-121) in PRVCV (P < .001). Volume delivered with Servo-i was 133 mL (95% confidence interval, 130-136) in VCV, 108 mL (95% confidence interval, 104-111) in PCV, and 104 (95% confidence interval, 101-108) in PRVCV (P < .001). ConclusionsIn high-resistance simulations, the delivered volume was lower when using PCV or PRVCV modes than VCV mode. Pressure control ventilation or PRVCV may fail to provide programmed TV, ultimately leading to hypoventilation of the patient.