Changes In Ventilator Settings Research Articles

Pulmonary response prediction through personalized basis functions in a virtual patient model

Background and ObjectiveRecruitment maneuvers with subsequent positive-end-expiratory-pressure (PEEP) have proven effective in recruiting lung volume and preventing alveoli collapse. However, determining a safe, effective, and patient-specific PEEP is not standardized, and this more optimal PEEP level evolves with patient condition, requiring personalised monitoring and care approaches to maintain optimal ventilation settings. MethodsThis research examines 3 physiologically relevant basis function sets (exponential, parabolic, cumulative) to enable better prediction of elastance evolution for a virtual patient or digital twin model of MV lung mechanics, including novel elements to model and predict distension elastance. Prediction accuracy and robustness are validated against recruitment maneuver data from 18 volume-controlled ventilation (VCV) patients at 7 different baseline PEEP levels (0 to 12 cmH2O) and 14 pressure-controlled ventilation (PCV) patients at 4 different baseline PEEP levels (6 to 12 cmH2O), yielding 623 and 294 prediction cases, respectively. Predictions were made up to 12 cmH2O of added PEEP ahead, covering 6 × 2 cmH2O PEEP steps. ResultsThe 3 basis function sets yield median absolute peak inspiratory pressure (PIP) prediction error of 1.63 cmH2O for VCV patients, and median peak inspiratory volume (PIV) prediction error of 0.028 L for PCV patients. The exponential basis function set yields a better trade-off of overall performance across VCV and PCV prediction than parabolic and cumulative basis function sets from other studies. Comparing predicted and clinically measured distension prediction in VCV demonstrated consistent, robust high accuracy with R2 = 0.90–0.95. ConclusionsThe results demonstrate recruitment mechanics are best captured by an exponential basis function across different mechanical ventilation modes, matching physiological expectations, and accurately capture, for the first time, distension mechanics to within 5–10 % accuracy. Enabling the risk of lung injury to be predicted before changing ventilator settings. The overall outcomes significantly extend and more fully validate this digital twin or virtual mechanical ventilation patient model.

Pulmonary Response Prediction Comparison through Three Personalized Basis Functions in a Virtual Patient Model

Recruitment manoeuvres with subsequent positive-end-expiratory-pressure (PEEP) have proved effective in recruiting lung volume and preventing alveoli collapse. However, determining a safe, effective, and patient-specific positive end-expiratory pressure (PEEP) is not standardized. This study examines three physiologically relevant basis function sets in conjunction with Hysteresis Loop Modelling (HLM) to enable better elastance evolution predictions for a virtual patient model, adding novel elements to model and predict distension. Prediction accuracy and robustness are validated against 18 volume controlled ventilated (VCV) patients at 7 different baseline PEEP levels (0 to 12cmH2O) yielding 623 cases. Predictions were made, up to 12cmH2O covering 6 × 2cmH2O PEEP steps. The 3 basis function sets yield an absolute median peak inspiratory pressure prediction error of 1.63cmH2O for VCV patients. Overall results demonstrate recruitment mechanics are best captured by an exponential basis function, matching physiological expectations, and accurately capture, for the first time, distension mechanics enabling the risk of lung injury to be predicted before changing ventilator settings. The overall outcomes significantly extend and more fully validate this virtual mechanical ventilation patient model.

Outcome of Tracheostomy in COVID-19 Patients.

Since the start of the COVID-19 pandemic 2019, quite a few patients became critical and needed ICU admission with ventilator assistance. Tracheostomy, which was initially performed late during the course of patient on ventilator, has now been considered a procedure that can be performed relatively early as this leads to early weaning of patients and overcomes the shortage of critical beds. This study aims to focus on the outcomes of tracheotomised COVID-19 patients in terms of survival and any tracheostomy related morbidity. A prospective study was performed on COVID-19 patients undergoing tracheostomy at this tertiary care teaching hospital, which also was a dedicated centre for treating COVID-19 patients. The duration of this study was from April 2020 to September 2021. Following tracheostomy, all patients were followed up regularly and clinical changes were recorded. Points that were specifically noted were timing of the tracheostomy, change in ventilator settings, tracheostomy related complications, requirement of oxygen, days needed to wean the patient, decanulation, and, if death, the cause of death. A total of 136 surgical open tracheostomies were performed on COVID-19 patients over the study period. The mean duration of intubation (timing of tracheostomy) was 12 days. A total of 73 out of 136 (53.6%) patients survived. 51 patients (37.5%) got decannulated during the course of the hospital stay. 9 patients were decanulated during the follow up visits and 13 patients were lost to follow up. 63 out of 136 (46.3%) patients died due to COVID pneumonia. Most of the patients who died had gone into multi-organ failure. Air leak syndromes (pneumothorax and pneumomediastinum) were common findings. 10 patients already had surgical emphysema before taking up for tracheostomy and 6 developed 2-3 days after tracheostomy. The most common complication was bleeding, which was seen in 28 out of 136 patients. The Median weaning of period of patients who survived was 5 days. Performing tracheostomy early in COVID-19 patients helps in early weaning of the patient from the ventilator and makes nursing care easier and increases the availability of ICU beds. The mortality rate was 46% amongst the 136 tracheostomies done in COVID-19 patients. Local site bleeding was the most common complication and surgical emphysema was also seen more than routine tracheostomies. The online version contains supplementary material available at 10.1007/s12070-022-03248-1.

Physiotherapy practices when treating patients with COVID-19 during a pandemic: A survey study

Background Specific details pertaining to the clinical and other challenges faced by physiotherapists managing patients with COVID-19 during the pandemic are still largely unknown.Objectives To determine how physiotherapists clinically managed patients with COVID-19 in a hospital-based setting during the pandemic and to identify the personal and professional effects of working as a physiotherapist at this time.Methods Self-administered electronic cross-sectional survey. Participants included physiotherapists from around the world involved in the clinical management of patients with COVID-19.Results Of the 204 participants who returned the questionnaire, 39% worked as senior physiotherapists, 29% as consultant or specialist physiotherapists, 23% as general physiotherapists and 4% as graduate physiotherapists. Seventy-two percent of participants worked in the intensive care unit. The largest barrier to treating patients with COVID-19 was a lack of intensive care trained physiotherapists (70%). Eighty-three percent of participants reported performing activities outside of their typical work duties, including proning patients (55%), tutoring and advising other staff in the intensive care unit (55%) and adjusting or changing ventilator settings (52%). Almost all participants (90%) reported being aware of physiotherapy specific guidelines for treating patients with COVID-19, yet most participants performed techniques that were not recommended.Conclusions The experience of the pandemic highlighted the need for specialist training and availability of experienced cardiorespiratory physiotherapists to manage patients with COVID-19, specifically in intensive care. Furthermore, clear guidelines on the management of patients with COVID-19 should be established to ensure optimal management of patients and ensure the safety of physiotherapy staff.

The Efficacy and Safety of Automatic Modes During Respiratory Support After Cardiac Surgery

Aims. To compare the efficacy and safety of semiautonomous Adaptive Support Ventilation (ASV) and fully automated (closed-loop, Intellivent-ASV) mechanical ventilation and oxygenation versus conventional mechanical ventilation mode during respiratory support in cardiac surgery patients.Material and methods. In this study, 40 adult patients were ventilated by conventional mechanical ventilation managed by 8 physicians (control group), whereas other two groups patients were ventilated by Intellivent-ASV (n=40) or in a semiautomatic ASV mode (n=40). The groups received standard care, except for the modes of ventilation.Results. In the Intellivent-ASV group, the number of manual changes in ventilator settings was significantly lower: 0 (0–0) versus 2 (2–3) (ASV) and 4 (3–5) in the control group (P<0.0001). There were significant differences in the duration of respiratory support in ICU which was 226±31 min (Intellivent group) vs 259±66 (ASV) and 271±78 min (control) (P=0.0042; P1–2=0.0167; P1–3=0.009). The Intellivent-ASV group patients received more protective ventilation than patients in the semiautomated and physician-controlled groups (lower values of driving pressure (6 (6–7) cm H2O vs. 6 (6–7) and 7 (7–9) cm H2O (P<0.0001)), tidal volume (6 (6–7) vs. 7 (7–7.7) and 7 (7–8) ml/kg/PBW (P<0.0001)), FiO2 (26 (24–30)% vs. 34 (30–35)% and 34 (30–38)%) with no differences between the groups in paO2/FiO2. There were no significant differences between the groups in frequency of undesirable events and duration of ICU stay.Conclusion. The use of intelligent technologies makes it possible to interactively individualize respiratory support, significantly reducing clinician's involvement in this process without compromising patient safety and the quality of ventilation.

Over-distension prediction via hysteresis loop analysis and patient-specific basis functions in a virtual patient model

Background and objectiveRecruitment maneuvers (RMs) with subsequent positive-end-expiratory-pressure (PEEP) have proven effective in recruiting lung volume and preventing alveolar collapse. However, a suboptimal PEEP could induce undesired injury in lungs by insufficient or excessive breath support. Thus, a predictive model for patient response under PEEP changes could improve clinical care and lower risks. MethodsThis research adds novel elements to a virtual patient model to identify and predict patient-specific lung distension to optimise and personalise care. Model validity and accuracy are validated using data from 18 volume-controlled ventilation (VCV) patients at 7 different baseline PEEP levels (0–12cmH2O), yielding 623 prediction cases. Predictions were made up to ΔPEEP = 12cmH2O ahead covering 6x2cmH2O PEEP steps. ResultsUsing the proposed lung distension model, 90% of absolute peak inspiratory pressure (PIP) prediction errors compared to clinical measurement are within 3.95cmH2O, compared with 4.76cmH2O without this distension term. Comparing model-predicted and clinically measured distension had high correlation increasing to R2 = 0.93–0.95 if maximum ΔPEEP ≤ 6cmH2O. Predicted dynamic functional residual capacity (Vfrc) changes as PEEP rises yield 0.013L median prediction error for both prediction groups and overall R2 of 0.84. ConclusionsOverall results demonstrate nonlinear distension mechanics are accurately captured in virtual lung mechanics patients for mechanical ventilation, for the first time. This result can minimise the risk of lung injury by predicting its potential occurrence of distension before changing ventilator settings. The overall outcomes significantly extend and more fully validate this virtual mechanical ventilation patient model.

Annual Respiratory Evaluations in Congenital Central Hypoventilation Syndrome and Changes in Ventilatory Management.

Background: Annual in-hospital respiratory evaluations (AREs) during wakefulness and sleep are recommended to assess ventilatory requirements in patients with congenital central hypoventilation syndrome (CCHS) aged ≥2-3 years based on expert consensus. This study aimed to determine if AREs in patients with CCHS led to changes in ventilatory management. Methods: Retrospective review of patients with CCHS who underwent AREs with or without polysomnography between 2017 and 2019 was conducted. Clinical symptoms, results of AREs, and subsequent changes in ventilatory management were analyzed. Results: We identified 10 patients with CCHS aged 4-20 years. All patients required assisted ventilation (AV) only during sleep delivered by positive pressure ventilation via tracheostomy (n = 7) or diaphragm pacing (n = 3). In total, 7 (70%) patients had abnormal oxygenation and/or ventilation requiring changes in ventilator settings or duration of AV. Six patients required an increase in settings and/or duration of AV, and only 1 patient required a decrease in ventilator settings. Two patients had awake hypercapnia during a routine outpatient visit that improved following increase in ventilator settings and a period of continuous AV. One patient who was previously ventilator-dependent only during sleep was identified to require 16 h per day of AV. All patients (n = 3) who reported symptoms such as headache or oxygen desaturations during sleep required an increase in ventilator settings. Conclusion: We report a high prevalence of changes in AV management following an ARE. Our results demonstrate the importance of regular AREs in patients with CCHS to assess their ventilatory requirements and optimize AV.

In silico numerical simulation of ventilator settings during high-frequency ventilation in preterm infants.

Despite the routine use of antenatal steroids, exogenous surfactants, and different noninvasive ventilation methods, many extremely low gestational age neonates, preterm, and term infants eventually require invasive ventilation. In addition to prematurity, mechanical ventilation itself can induce ventilator-induced lung injury leading to lifelong pulmonary sequelae. Besides conventional mechanical ventilation, high-frequency oscillatory ventilation (HFOV) with tidal volumes below dead space and high ventilation frequencies is used either as a primary or rescue therapy in severe neonatal respiratory failure. Applying a high-resolution computational lung modeling technique in a preterm infant, we studied three different high-frequency ventilation settings as well as conventional ventilation (CV) settings. Evaluating the computed oxygen delivery (OD) and lung mechanics (LM) we outline for the first time how changing ventilator settings from CV to HFOV lead to significant improvements in OD and LM. This personalized "digital twin" strategy advances our general knowledge of protective ventilation strategies in neonatal care and can support decisions on various modes of ventilatory therapy at high frequencies.

Effects of PEEP on the relationship between tidal volume and total impedance change measured via electrical impedance tomography (EIT).

Electrical impedance tomography (EIT) is used in lung physiology monitoring. There is evidence that EIT is linearly associated with global tidal volume (VT) in clinically healthy patients where no positive end-expiratory pressure (PEEP) is applied. This linearity has not been challenged by altering lung conditions. The aim of this study was to determine the effect of PEEP on VT estimation, using EIT technology and spirometry, and observe the stability of the relationship under changing lung conditions. Twelve male castrated cattle (Steer), mean age 7.8 months (SD ± 1.7) were premedicated with xylazine followed by anaesthesia induction with ketamine and maintenance with halothane in oxygen via an endotracheal tube. An EIT belt was applied around the thorax at the level of the fifth intercostal space. Volume controlled ventilation was used. PEEP was increased in a stepwise manner from 0 to 5, 10 and 15 cmH2O. At each PEEP, the VT was increased stepwise from 5 to 10 and 15 mL kg−1. After a minute of stabilisation, total impedance change (VTEIT), using EIT and VT measured by a spirometer connected to a flow-partitioning device (VTSpiro) was recorded for the following minute before changing ventilator settings. Data was analysed using linear regression and multi variable analysis. There was a linear relationship between VTEIT and VTSpiro at all levels of PEEP with an R2 of 0.71, 0.68, 0.63 and 0.63 at 0, 5, 10 and 15 cmH2O, respectively. The variance in VTEIT was best described by peak inspiratory pressure (PIP) and PEEP (adjusted R2 0.82) while variance in VTSpiro was best described by PIP and airway deadspace (adjusted R2 0.76). The relationship between VTEIT and VTSpiro remains linear with changes in tidal volume, and stable across altered lung conditions. This may have application for monitoring and assessment in vivo.

Redeployment to COVID-19 Care Is Like Treading Water but Deeply Gratifying

Back to table of contents Previous article Next article Residents’ ForumFull AccessRedeployment to COVID-19 Care Is Like Treading Water but Deeply GratifyingRuth McCann, M.D.Ruth McCannSearch for more papers by this author, M.D.Published Online:28 Apr 2020https://doi.org/10.1176/appi.pn.2020.5a36AbstractAs a third-year psychiatry resident in New York, I’ve been redeployed to care for COVID-19 patients in our hospital. For now, I’m working in a medical intensive care unit (ICU), functioning in the role of an intern. I am, truly, more than happy to do this.The word “redeployment” feels odd, though. Was I ever “deployed” to begin with? I’ve never thought of doctors as soldiers. But if we’re now at war, it feels tricky—if not impossible—to say what or who the enemy is and what winning or losing might look like.After the shelter-in-place orders began, I spent two weeks doing remote visits with my outpatients by phone and Zoom. Ambulance sirens were almost constant. I felt guilty being at home and safe when I might reasonably be able to help in the hospital. So I volunteered for so-called redeployment, and my clinic director very kindly offered to cover my outpatients.After a few days of waiting, I was sent to work in a surgical ICU that had been converted into a COVID ICU. In fact, almost every available space in our hospital is now functioning as an ICU, including most of the operating rooms.Seven of my co-residents have also been redeployed to medical wards or ICU settings, and others are manning a new palliative care team. Still others have volunteered and are awaiting assignments. Thankfully, our intern years involved rotations in internal medicine (wards and ICU), neurology, and emergency medicine, so we arrived not entirely unprepared.So far, I’ve been working overnight shifts alongside many others who’ve been redeployed, including residents and fellows from anesthesia, surgery, orthopedics, and pediatrics. Our current supervisors are extremely competent cardiologists who’ve stepped up to run the ICU in which I am working.I’m essentially an intern again. I follow up lab results and order X-rays. I help nurses turn patients in bed. I call families and consults. I write admission notes, transfer notes, and death notes (of which there’ve been a heartbreaking number). In essence, I provide basic, hands-on assistance to my supervisors and the outstanding ICU nurses. And I do have an N95 that I use and reuse.The hospital—my home institution since medical school—is eerily tense and often quiet. Medical students have been sent home, and visitors are no longer allowed.It has admittedly been an adjustment to go from being a competent third-year psychiatry resident to being—again—an intern treading water. I am, in this new setting, not particularly special or talented or authoritative. No one looks to me for any kind of answer. I do what I can and what I’m asked. The experience is somewhat similar to how it felt to stay at home and isolated from the people I love—difficult but not unique. We’re all doing it; we’re all in this together.There are, I know, grave ethical, political, and social questions to be asked right now. People everywhere are suffering and dying. Our medical system is broken and breaking further. Many health care workers across the country are not being adequately protected, supported, or compensated during this crisis.But to push myself from today into tomorrow, I’ve sometimes avoided thinking about the forest. I’ve relied, instead, on the solidity of various trees. I wish, for example, that I could adequately express to you the joy I felt the other night as I watched my attending care for patients on our unit. She flew, seemingly tireless, from room to room, putting out fire after fire, changing ventilator settings, running codes, calling families, and answering every question the nurses and I came to her with. She was dedicated, kind, and indefatigable. I wished the patients’ families could see her, ministering so beautifully and intently to their loved ones.There’s been a nightly 7 p.m. “Clap for Carers” in Manhattan, and I’ll admit that I sometimes ignore it, because it hurts to think about what’s happening. But yesterday, when the clapping started, I went to the window and joined in. I clapped for that particular attending and for the work I’d seen her do—something like war, maybe, but more like love. ■Ruth McCann, M.D., is a PGY-3 psychiatry resident at Columbia University Irving Medical Center/New York State Psychiatric Institute. ISSUES NewArchived

Effects of small tidal volume and positive end-expiratory pressure on oxygenation in pressure-controlled ventilation-volume guaranteed mode during one-lung ventilation

Introduction The purpose of this study was to investigate whether tidal volume (TV) of 8 mL/kg without positive end-expiratory pressure (PEEP) and TV of 6 mL/kg with or without PEEP in pressure-controlled, ventilation-volume guaranteed (PCV-VG) mode can maintain arterial oxygenation and decrease inspiratory airway pressure effectively during one-lung ventilation (OLV). Methods The study enrolled 27 patients undergoing thoracic surgery. All patients were ventilated with PCV-VG mode. During OLV, patients were initially ventilated with TV 8 mL/kg (group TV8) without PEEP. Ventilation was subsequently changed to TV 6 mL/kg with PEEP (5 cmH2O; group TV6+PEEP) or without (group TV6) in random sequence. Peak inspiratory pressure (Ppeak), mean airway pressure (Pmean), and arterial blood gas analysis were measured 30 min after changing ventilator settings. Ventilation was then changed once more to add or eliminate PEEP (5 cmH2O), while maintaining TV 6 mL/kg. Thirty min after changing ventilator settings, the same parameters were measured once more. Results The Ppeak was significantly lower in group TV6 (19.3±3.3 cmH2O) than in group TV8 (21.8±3.1 cmH2O) and group TV6+PEEP (20.1±3.4 cmH2O). PaO2 was significantly higher in group TV8 (242.5±111.4 mmHg) than in group TV6 (202.1±101.3 mmHg) (P = 0.044). There was no significant difference in PaO2 between group TV8 and group TV6+PEEP (226.8±121.1 mmHg). However, three patients in group TV6 were dropped from the study because PaO2 was lower than 80 mmHg after ventilation. Discussion It is postulated that TV 8 mL/kg without PEEP or TV 6 mL/kg with 5 cmH2O PEEP in PCV-VG mode during OLV can safely maintain adequate oxygenation.

Temporal Changes in Ventilator Settings in Patients With Uninjured Lungs: A Systematic Review.

In patients with uninjured lungs, increasing evidence indicates that tidal volume (VT) reduction improves outcomes in the intensive care unit (ICU) and in the operating room (OR). However, the degree to which this evidence has translated to clinical changes in ventilator settings for patients with uninjured lungs is unknown. To clarify whether ventilator settings have changed, we searched MEDLINE, Cochrane Central Register of Controlled Trials, and Web of Science for publications on invasive ventilation in ICUs or ORs, excluding those on patients <18 years of age or those with >25% of patients with acute respiratory distress syndrome (ARDS). Our primary end point was temporal change in VT over time. Secondary end points were changes in maximum airway pressure, mean airway pressure, positive end-expiratory pressure, inspiratory oxygen fraction, development of ARDS (ICU studies only), and postoperative pulmonary complications (OR studies only) determined using correlation analysis and linear regression. We identified 96 ICU and 96 OR studies comprising 130,316 patients from 1975 to 2014 and observed that in the ICU, VT size decreased annually by 0.16 mL/kg (-0.19 to -0.12 mL/kg) (P < .001), while positive end-expiratory pressure increased by an average of 0.1 mbar/y (0.02-0.17 mbar/y) (P = .017). In the OR, VT size decreased by 0.09 mL/kg per year (-0.14 to -0.04 mL/kg per year) (P < .001). The change in VTs leveled off in 1995. Other intraoperative ventilator settings did not change in the study period. Incidences of ARDS (ICU studies) and postoperative pulmonary complications (OR studies) also did not change over time. We found that, during a 39-year period, from 1975 to 2014, VTs in clinical studies on mechanical ventilation have decreased significantly in the ICU and in the OR.

Rescue high frequency ventilation for congenital diaphragmatic hernia.

High frequency jet (HFJV) and oscillatory (HFOV) ventilation were used to rescue newborns with congenital diaphragmatic hernia (CDH), who failed conventional mechanical ventilation (CV). Changes in ventilator settings and pulmonary gas exchange were evaluated following transition to high frequency ventilation (HFV). Records of patients with CDH rescued with HFV prior to surgical intervention between 2006 and 2015 were reviewed. Mean airway pressure (Pāw) and arterial blood gases during CV and those obtained within the first hour of HFV were compared. A composite repeated measure analysis was performed to evaluate longitudinal and intergroup variances. Twenty-seven patients were rescued from CV, 16 by HFJV and 11 by HFOV. The two groups had similar gestational ages and birth weights. Prior to HFV, both groups had similar Pāw, PaCO2, FiO2 and PaO2. HFV was associated with a significant improvement in ventilation, and the rate of decrease of PaCO2 was no different between groups. There was a significantly higher increase in Pāw increase with HFOV compared to HFJV. In newborns with CDH rescued with HFV, ventilation improved but Pāw was significantly lower in patients supported with HFJV compared to HFOV.

Changes in ventilator settings and ventilation-induced lung injury in burn patients-A systematic review.

Ventilation strategies aiming at prevention of ventilator-induced lung injury (VILI), including low tidal volumes (VT) and use of positive end-expiratory pressures (PEEP) are increasingly used in critically ill patients. It is uncertain whether ventilation practices changed in a similar way in burn patients. Our objective was to describe applied ventilator settings and their relation to development of VILI in burn patients. Systematic search of the literature in PubMed and EMBASE using MeSH, EMTREE terms and keywords referring to burn or inhalation injury and mechanical ventilation. Studies reporting ventilator settings in adult or pediatric burn or inhalation injury patients receiving mechanical ventilation during the ICU stay. Two authors independently screened abstracts of identified studies for eligibility and performed data extraction. The search identified 35 eligible studies. VT declined from 14 ml/kg in studies performed before to around 8 ml/kg predicted body weight in studies performed after 2006. Low-PEEP levels (<10 cmH2O) were reported in 70% of studies, with no changes over time. Peak inspiratory pressure (PIP) values above 35 cmH2O were frequently reported. Nevertheless, 75% of the studies conducted in the last decade used limited maximum airway pressures (≤35 cmH2O) compared to 45% of studies conducted prior to 2006. Occurrence of barotrauma, reported in 45% of the studies, ranged from 0 to 29%, and was more frequent in patients ventilated with higher compared to lower airway pressures. This systematic review shows noticeable trends of ventilatory management in burn patients that mirrors those in critically ill non-burn patients. Variability in available ventilator data precluded us from drawing firm conclusions on the association between ventilator settings and the occurrence of VILI in burn patients.

Clinical Scenarios of the Application of Electrical Impedance Tomography in Paediatric Intensive Care

EIT is a radiation-free functional modality that enables bedside imaging and monitoring of lung function and expansion. Clinical interest in this method has been driven by the need for bedside monitoring of the dynamics of the lungs and the effects of ventilatory manoeuvres, including changes in ventilator settings, suctioning, chest drains, positioning and physiotherapy. We aimed to describe the use of Electrical Impedance Tomography (EIT) as a clinical tool in a tertiary Paediatric Intensive Care unit. Children requiring intensive care with a variety of clinical conditions had an electrode belt with 16 electrodes wrapped around the chest, which sequentially applied a small alternating current from each electrode pair. The signal gives information on both real time, regional, global, and relative data. With the correct application, and understanding of the monitor, much clinical information can be gained, with potentially significant patient benefit. We present the clinical use of EIT in six conditions: Asthma, Ventilation weaning and expansion recoil, Sequential Lobar Collapse, Targeted Physiotherapy, Pleural Effusion assessment, and PEEP optimisation. Screenshots and analyses are offered displaying the pragmatic use of this technology. Electrical Impedance Tomography is a clinically useful tool on the Paediatric Intensive Care unit. It allows monitoring of a patient’s respiratory function in ways which are not possible through any other means. An understanding of respiratory physiology will allow use of this information to improve patient outcomes.

Effects of small tidal volume and positive end-expiratory pressure on oxygenation in pressure-controlled ventilation-volume guaranteed mode during one-lung ventilation.

BackgroundThe purpose of this study was to investigate whether tidal volume (TV) of 8 mL/kg without positive end-expiratory pressure (PEEP) and TV of 6 mL/kg with or without PEEP in pressure-controlled ventilation-volume guaranteed (PCV-VG) mode can maintain arterial oxygenation and decrease inspiratory airway pressure effectively during one-lung ventilation (OLV).MethodsThe study enrolled 27 patients undergoing thoracic surgery. All patients were ventilated with PCV-VG mode. During OLV, patients were initially ventilated with TV 8 mL/kg (group TV8) without PEEP. Ventilation was subsequently changed to TV 6 mL/kg with PEEP (5 cmH2O; group TV6+PEEP) or without (group TV6) in random sequence. Peak inspiratory pressure (Ppeak), mean airway pressure (Pmean), and arterial blood gas analysis were measured 30 min after changing ventilator settings. Ventilation was then changed once more to add or eliminate PEEP (5 cmH2O), while maintaining TV 6 mL/kg. Thirty min after changing ventilator settings, the same parameters were measured once more.ResultsThe Ppeak was significantly lower in group TV6 (19.3±3.3 cmH2O) than in group TV8 (21.8±3.1 cmH2O) and group TV6+PEEP (20.1±3.4 cmH2O). PaO2 was significantly higher in group TV8 (242.5±111.4 mmHg) than in group TV6 (202.1±101.3 mmHg) (p=0.044). There was no significant difference in PaO2 between group TV8 and group TV6+PEEP (226.8±121.1 mmHg). However, three patients in group TV6 were dropped from the study because PaO2 was lower than 80 mmHg after ventilation.ConclusionIt is postulated that TV 8 mL/kg without PEEP or TV 6 mL/kg with 5 cmH2O PEEP in PCV-VG mode during OLV can safely maintain adequate oxygenation.

Variability in Usual Care Mechanical Ventilation for Pediatric Acute Respiratory Distress Syndrome: Time for a Decision Support Protocol?

Although pediatric intensivists philosophically embrace lung protective ventilation for acute lung injury and acute respiratory distress syndrome, we hypothesized that ventilator management varies. We assessed ventilator management by evaluating changes to ventilator settings in response to blood gases, pulse oximetry, or end-tidal CO2. We also assessed the potential impact that a pediatric mechanical ventilation protocol adapted from National Heart Lung and Blood Institute acute respiratory distress syndrome network protocols could have on reducing variability by comparing actual changes in ventilator settings to those recommended by the protocol. Prospective observational study. Eight tertiary care U.S. PICUs, October 2011 to April 2012. One hundred twenty patients (age range 17 d to 18 yr) with acute lung injury/acute respiratory distress syndrome. Two thousand hundred arterial and capillary blood gases, 3,964 oxygen saturation by pulse oximetry, and 2,757 end-tidal CO2 values were associated with 3,983 ventilator settings. Ventilation mode at study onset was pressure control 60%, volume control 19%, pressure-regulated volume control 18%, and high-frequency oscillatory ventilation 3%. Clinicians changed FIO2 by ±5 or ±10% increments every 8 hours. Positive end-expiratory pressure was limited at ~10 cm H2O as oxygenation worsened, lower than would have been recommended by the protocol. In the first 72 hours of mechanical ventilation, maximum tidal volume/kg using predicted versus actual body weight was 10.3 (8.5-12.9) (median [interquartile range]) versus 9.2 mL/kg (7.6-12.0) (p < 0.001). Intensivists made changes similar to protocol recommendations 29% of the time, opposite to the protocol's recommendation 12% of the time and no changes 56% of the time. Ventilator management varies substantially in children with acute respiratory distress syndrome. Opportunities exist to minimize variability and potentially injurious ventilator settings by using a pediatric mechanical ventilation protocol offering adequately explicit instructions for given clinical situations. An accepted protocol could also reduce confounding by mechanical ventilation management in a clinical trial.

Emergency Department Blood Gas Utilization and Changes in Ventilator Settings.

Mechanically ventilated patients increasingly spend hours in emergency department beds before ICU admission. This study evaluated the performance of blood gases in mechanically ventilated subjects in the emergency department and subsequent changes to mechanical ventilation settings. This was a multi-center, prospective, observational study of subjects ventilated in the emergency department, conducted at 3 academic emergency departments from July 2011 to March 2013. We measured the rate of arterial blood gas (ABG) and venous blood gas (VBG) analysis, and we assessed the associations between the conditions of hypoxemia, hyperoxia, hypercapnia, or acidemia and changes to mechanical ventilator settings. Of 292 ventilated subjects, 17.1% did not have a blood gas sent in the emergency department. Ventilator changes were made significantly more frequently for subjects who had an ABG as the initial blood gas sent in the emergency department (odds ratio 2.70, 95% CI 1.46-4.99, P = .002). However, findings of hypoxemia, hyperoxia, hypercapnia, or acidemia were not correlated with ventilator adjustments. In this prospective observational study of subjects mechanically ventilated in the emergency department, the majority had a blood gas checked while in the emergency department. While ABGs were associated with having changes made to ventilator settings in the emergency department, clinical findings of hypoxemia, hyperoxia, hypercapnia, and acidemia were not. Inattention to blood gas results may lead to missed opportunities in guiding ventilator changes in the emergency department.

Potential Acceptability of a Pediatric Ventilator Management Computer Protocol.

To examine issues regarding the granularity (size/scale) and potential acceptability of recommendations in a ventilator management protocol for children with pediatric acute respiratory distress syndrome. Survey/questionnaire. The eight PICUs in the Collaborative Pediatric Critical Care Research Network. One hundred twenty-two physicians (attendings and fellows). None. We used an online questionnaire to examine attitudes and assessed recommendations with 50 clinical scenarios. Overall 80% of scenario recommendations were accepted. Acceptance did not vary by provider characteristics but did vary by ventilator mode (high-frequency oscillatory ventilation 83%, pressure-regulated volume control 82%, pressure control 75%; p = 0.002) and variable adjusted (ranging from 88% for peak inspiratory pressure and 86% for FIO2 changes to 69% for positive end-expiratory pressure changes). Acceptance did not vary based on child size/age. There was a preference for smaller positive end-expiratory pressure changes but no clear granularity preference for other variables. Although overall acceptance rate for scenarios was good, there was little consensus regarding the size/scale of ventilator setting changes for children with pediatric acute respiratory distress syndrome. An acceptable protocol could support robust evaluation of ventilator management strategies. Further studies are needed to determine if adherence to an explicit protocol leads to better outcomes.

Where are we heading with fluid responsiveness research?

Fluid responsiveness prediction is not always possible with well established dynamic approaches such as passive leg raising or pulse pressure variation in the ICU. The purpose of the present review is to summarize emerging alternative techniques for fluid responsiveness prediction in adult critically ill patients and discuss their methodology and applicability. In addition, the future role of fluid responsiveness prediction in the ICU is discussed. Several new dynamic techniques have been investigated and they all contribute to the applicability of fluid responsiveness techniques. Although increasing the applicability, most of the emerging techniques still rely on ventilator setting changes in patients that are fully or almost fully adapted to the ventilator or require reliable flow monitoring, which prevents broad applicability. Yet, the mini/micro fluid challenges and the use of extrasystolic preload changes have the potential of being more applicable but all reviewed methods need further validation and methodological refinement. Emerging techniques are encouraging for broader applicability of fluid responsiveness prediction. Still, the clinical impact of correctly predicting fluid responsiveness remains to be investigated in the critically ill and the research community should have a clear aim of moving toward that type of studies.