Expiratory flow limitation during mechanical ventilation: real-time detection and physiological subtypes.

BACKGROUND: Tidal expiratory flow limitation (EFLT) complicates the delivery of mechanical ventilation but is only diagnosed by performing specific manoeuvres. Instantaneous analysis of expiratory resistance (Rex) can be an alternative way to detect EFLT without changing ventilatory settings. This study aimed to determine the agreement of EFLT detection by Rex analysis and the PEEP reduction manoeuvre using contingency table and agreement coefficient. The patterns of Rex were explored. METHODS: Medical patients ≥ 15-year-old receiving mechanical ventilation underwent a PEEP reduction manoeuvre from 5 cmH2O to zero for EFLT detection. Waveforms were recorded and analyzed off-line. The instantaneous Rex was calculated and was plotted against the volume axis, overlapped by the flow-volume loop for inspection. Lung mechanics, characteristics of the patients, and clinical outcomes were collected. The result of the Rex method was validated using a separate independent dataset. RESULTS: 339 patients initially enrolled and underwent a PEEP reduction. The prevalence of EFLT was 16.5%. EFLT patients had higher adjusted hospital mortality than non-EFLT cases. The Rex method showed 20% prevalence of EFLT and the result was 90.3% in agreement with PEEP reduction manoeuvre. In the validation dataset, the Rex method had resulted in 91.4% agreement. Three patterns of Rex were identified: no EFLT, early EFLT, associated with airway disease, and late EFLT, associated with non-airway diseases, including obesity. In early EFLT, external PEEP was less likely to eliminate EFLT. CONCLUSIONS: The Rex method shows an excellent agreement with the PEEP reduction manoeuvre and allows real-time detection of EFLT. Two subtypes of EFLT are identified by Rex analysis. TRIAL REGISTRATION: Clinical trial registered with www.thaiclinicaltrials.org (TCTR20190318003). The registration date was on 18 March 2019, and the first subject enrollment was performed on 26 March 2019.

Noninvasive ventilation and high-flow nasal cannula in patients with acute hypoxemic respiratory failure by covid-19: A retrospective study of the feasibility, safety and outcomes.

BACKGROUND: Noninvasive ventilation (NIV) and High-flow nasal cannula (HFNC) are the main forms of treatment for acute respiratory failure. This study aimed to evaluate the effect, safety, and applicability of the NIV and HFNC in patients with acute hypoxemic respiratory failure (AHRF) caused by COVID-19. METHODS: In this retrospective study, we monitored the effect of NIV and HFNC on the SpO2 and respiratory rate before, during, and after treatment, length of stay, rates of endotracheal intubation, and mortality in patients with AHRF caused by COVID-19. Additionally, data regarding RT-PCR from physiotherapists who were directly involved in assisting COVID-19 patients and non-COVID-19. RESULTS: 62.2 % of patients were treated with HFNC. ROX index increased during and after NIV and HFNC treatment (P < 0.05). SpO2 increased during NIV treatment (P < 0.05), but was not maintained after treatment (P = 0.17). In addition, there was no difference in the respiratory rate during or after the NIV (P = 0.95) or HFNC (P = 0.60) treatment. The mortality rate was 35.7 % for NIV vs 21.4 % for HFNC (P = 0.45), while the total endotracheal intubation rate was 57.1 % for NIV vs 69.6 % for HFNC (P = 0.49). Two adverse events occurred during treatment with NIV and eight occurred during treatment with HFNC. There was no difference in the physiotherapists who tested positive for SARS-COV-2 directly involved in assisting COVID-19 patients and non-COVID-19 ones (P = 0.81). CONCLUSION: The application of NIV and HFNC in the critical care unit is feasible and associated with favorable outcomes. In addition, there was no increase in the infection of physiotherapists with SARS-CoV-2.

Identification of distinct clinical phenotypes of acute respiratory distress syndrome with differential responses to treatment.

BACKGROUND: Acute respiratory distress syndrome (ARDS) is a heterogeneous syndrome, and the identification of homogeneous subgroups and phenotypes is the first step toward precision critical care. We aimed to explore whether ARDS phenotypes can be identified using clinical data, are reproducible and are associated with clinical outcomes and treatment response. METHODS: This study is based on a retrospective analysis of data from the telehealth intensive care unit (eICU) collaborative research database and three ARDS randomized controlled trials (RCTs) (ALVEOLI, FACTT and SAILS trials). We derived phenotypes in the eICU by cluster analysis based on clinical data and compared the clinical characteristics and outcomes of each phenotype. The reproducibility of the derived phenotypes was tested using the data from three RCTs, and treatment effects were evaluated. RESULTS: Three clinical phenotypes were identified in the training cohort of 3875 ARDS patients. Of the three phenotypes identified, phenotype I (n = 1565; 40%) was associated with fewer laboratory abnormalities, less organ dysfunction and the lowest in-hospital mortality rate (8%). Phenotype II (n = 1232; 32%) was correlated with more inflammation and shock and had a higher mortality rate (18%). Phenotype III (n = 1078; 28%) was strongly correlated with renal dysfunction and acidosis and had the highest mortality rate (22%). These results were validated using the data from the validation cohort (n = 3670) and three RCTs (n = 2289) and had reproducibility. Patients with these ARDS phenotypes had different treatment responses to randomized interventions. Specifically, in the ALVEOLI cohort, the effects of ventilation strategy (high PEEP vs low PEEP) on ventilator-free days differed by phenotype (p = 0.001); in the FACTT cohort, there was a significant interaction between phenotype and fluid-management strategy for 60-day mortality (p = 0.01). The fluid-conservative strategy was associated with improved mortality in phenotype II but had the opposite effect in phenotype III. CONCLUSION: Three clinical phenotypes of ARDS were identified and had different clinical characteristics and outcomes. The analysis shows evidence of a phenotype-specific treatment benefit in the ALVEOLI and FACTT trials. These findings may improve the identification of distinct subsets of ARDS patients for exploration in future RCTs.

Higher versus lower positive end-expiratory pressure in patients without acute respiratory distress syndrome: a meta-analysis of randomized controlled trials.

BACKGROUND: We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) to assess the association of higher positive end-expiratory pressure (PEEP), as opposed to lower PEEP, with hospital mortality in adult intensive care unit (ICU) patients undergoing invasive mechanical ventilation for reasons other than acute respiratory distress syndrome (ARDS). METHODS: We performed an electronic search of MEDLINE, EMBASE, Scopus, Cochrane Central Register of Controlled Trials, CINAHL, and Web of Science from inception until June 16, 2021 with no language restrictions. In addition, a research-in-progress database and grey literature were searched. RESULTS: We identified 22 RCTs (2225 patients) comparing higher PEEP (1007 patients) with lower PEEP (991 patients). No statistically significant association between higher PEEP and hospital mortality was observed (risk ratio 1.02, 95% confidence interval 0.89-1.16; I2 = 0%, p = 0.62; low certainty of evidence). Among secondary outcomes, higher PEEP was associated with better oxygenation, higher respiratory system compliance, and lower risk of hypoxemia and ARDS occurrence. Furthermore, barotrauma, hypotension, duration of ventilation, lengths of stay, and ICU mortality were similar between the two groups. CONCLUSIONS: In our meta-analysis of RCTs, higher PEEP, compared with lower PEEP, was not associated with mortality in patients without ARDS receiving invasive mechanical ventilation. Further large high-quality RCTs are required to confirm these findings.

Management of ARDS - What Works and What Does Not.

Acute respiratory distress syndrome (ARDS) is a clinically and biologically heterogeneous disorder associated with a variety of disease processes that lead to acute lung injury with increased non-hydrostatic extravascular lung water, reduced compliance, and severe hypoxemia. Despite significant advances, mortality associated with this syndrome remains high. Mechanical ventilation remains the most important aspect of managing patients with ARDS. An in-depth knowledge of lung protective ventilation, optimal PEEP strategies, modes of ventilation and recruitment maneuvers are essential for ventilatory management of ARDS. Although, the management of ARDS is constantly evolving as new studies are published and guidelines being updated; we present a detailed review of the literature including the most up-to-date studies and guidelines in the management of ARDS. We believe this review is particularly helpful in the current times where more than half of the acute care hospitals lack in-house intensivists and the burden of ARDS is at large.

Improving Adherence to Intraoperative Lung-Protective Ventilation Strategies Using Near Real-Time Feedback and Individualized Electronic Reporting.

BACKGROUND: Postoperative pulmonary complications can have a significant impact on the morbidity and mortality of patients undergoing major surgeries. Intraoperative lung protective strategies using low tidal volume (TV) ventilation and positive end-expiratory pressure (PEEP) have been demonstrated to reduce the incidence of pulmonary injury and infection while improving oxygenation and respiratory mechanics. The purpose of this study was to develop decision support systems designed to optimize behavior of the attending anesthesiologist with regards to adherence with established intraoperative lung-protective ventilation (LPV) strategies. METHODS: Over a 4-year period, data were obtained from 49,386 procedures and 109 attendings. Cases were restricted to patients aged 18 years or older requiring general anesthesia that lasted at least 60 minutes. We defined protective lung ventilation as a TV of 6-8 mL/kg ideal body weight and a PEEP of ≥4 cm H2O. There was a baseline period followed by 4 behavioral interventions: education, near real-time feedback, individualized post hoc feedback, and enhanced multidimensional decision support. Segmented logistic regression using generalized estimating equations was performed in order to assess temporal trends and effects of interventions on adherence to LPV strategies. RESULTS: Consistent with improvement in adherence with LPV strategies during the baseline period, the predicted probability of adherence with LPV at the end of baseline was 0.452 (95% confidence interval [CI], 0.422-0.483). The improvements observed for each phase were relative to the preceding phase. Education alone was associated with an 8.7% improvement (P < .01) in adherence to lung-protective protocols and was associated with a 16% increase in odds of adherence (odds ratio [OR] = 1.16; 95% CI, 1.01-1.33; P = .04). Near real-time, on-screen feedback was associated with an estimated 15.5% improvement in adherence (P < .01) with a 69% increase in odds of adherence (OR = 1.69; 95% CI, 1.46-1.96; P < .01) over education alone. The addition of an individualized dashboard with personal adherence and peer comparison was associated with a significant improvement over near real-time feedback (P < .01). Near real-time feedback and dashboard feedback systems were enhanced based on feedback from the in-room attendings, and this combination was associated with an 18.1% (P < .01) increase in adherence with a 2-fold increase in the odds of adherence (OR = 2.23; 95% CI, 1.85-2.69; P < .0001) between the end of the previous on-screen feedback phase and the start of the individualized post hoc dashboard reporting phase. The adherence with lung-protective strategies using the multidimensional approach has been sustained for over 24 months. The difference between the end of the previous phase and the start of this last enhanced multidimensional decision support phase was not significant (OR = 1.08; 95% CI, 0.86-1.34; P = .48). CONCLUSIONS: Consistent with the literature, near real-time and post hoc reporting are associated with positive and sustained behavioral changes aimed at adopting evidence-based clinical strategies. Many decision support systems have demonstrated impact to behavior, but the effect is often transient. The implementation of near real-time feedback and individualized post hoc decision support tools has resulted in clinically relevant improvements in adherence with LPV strategies that have been sustained for over 24 months, a common limitation of decision support solutions.

Treatment-Emergent Central Apnea: Physiologic Mechanisms Informing Clinical Practice.

The purpose of this review was to describe our management approach to patients with treatment-emergent central sleep apnea (TECSA). The emergence of central sleep apnea during positive airway pressure therapy occurs in approximately 8% of titration studies for OSA, and it has been associated with several demographic, clinical, and polysomnographic factors, as well as factors related to the titration study itself. TECSA shares similar pathophysiology with central sleep apnea. In fact, central and OSA pathophysiologic mechanisms are inextricably intertwined, with ventilatory instability and upper airway narrowing occurring in both entities. TECSA is a "dynamic" process, with spontaneous resolution with ongoing positive airway pressure therapy in most patients, persistence in some, or appearing de novo in a minority of patients. Management strategy for TECSA aims to eliminate abnormal respiratory events, stabilize sleep architecture, and improve the underlying contributing medical comorbidities. CPAP therapy remains a standard therapy for TECSA. Expectant management is appropriate given its transient nature in most cases, whereas select patients would benefit from an early switch to an alternative positive airway pressure modality. Other treatment options include supplemental oxygen and pharmacologic therapy.

Performing sleep studies after the COVID-19 outbreak: practical suggestions from Bologna's sleep unit.

The Coronavirus Disease 2019 (COVID-19) pandemic required a thorough re-organization of every sector of the healthcare system. Sleep laboratories need to renew protocols in order to guarantee the safety of patients and healthcare staff while providing exams. Polysomnography (PSG) examinations are essential for the diagnosis and treatment management of several sleep disorders, which may constitute a public or personal safety issue such as obstructive sleep apnea syndrome. Here we provide some practical advice on how to perform sleep studies after the COVID-19 outbreak based on our experience, the review of the existing literature and current national and international recommendations by Health Authorities. We believe that with appropriate precautions it is possible to guarantee a safe restart of PSG and other sleep studies.

Effectiveness and safety of noninvasive positive pressure ventilation in the treatment of COVID-19-associated acute hypoxemic respiratory failure: a single center, non-ICU setting experience.

The role of noninvasive positive pressure ventilation (NIPPV) in COVID-19 patients with acute hypoxemic respiratory failure (AHRF) is uncertain, as no direct evidence exists to support NIPPV use in such patients. We retrospectively assessed the effectiveness and safety of NIPPV in a cohort of COVID-19 patients consecutively admitted to the COVID-19 general wards of a medium-size Italian hospital, from March 6 to May 7, 2020. Healthcare workers (HCWs) caring for COVID-19 patients were monitored, undergoing nasopharyngeal swab for SARS-CoV-2 in case of onset of COVID-19 symptoms, and periodic SARS-CoV-2 screening serology. Overall, 50 patients (mean age 74.6 years) received NIPPV, of which 22 (44%) were successfully weaned, avoiding endotracheal intubation (ETI) and AHRF-related death. Due to limited life expectancy, 25 (50%) of 50 NIPPV-treated patients received a "do not intubate" (DNI) order. Among these, only 6 (24%) were weaned from NIPPV. Of the remaining 25 NIPPV-treated patients without treatment limitations, 16 (64%) were successfully weaned, 9 (36%) underwent delayed ETI and, of these, 3 (33.3%) died. NIPPV success was predicted by the use of corticosteroids (OR 15.4, CI 1.79-132.57, p 0.013) and the increase in the PaO2/FiO2 ratio measured 24-48 h after NIPPV initiation (OR 1.02, CI 1-1.03, p 0.015), while it was inversely correlated with the presence of a DNI order (OR 0.03, CI 0.001-0.57, p 0.020). During the study period, 2 of 124 (1.6%) HCWs caring for COVID-19 patients were diagnosed with SARS-CoV-2 infection. Apart from patients with limited life expectancy, NIPPV was effective in a substantially high percentage of patients with COVID-19-associated AHRF. The risk of SARS-CoV-2 infection among HCWs was low.

Tracheostomy to Noninvasive Ventilation: From Acute Care to Home.

The number of patients experiencing prolonged mechanical ventilation is increasing over time. Patients who have a tracheostomy placed in a critical care setting have been described as having an average of 4 separate transitions between the acute care setting, long-term acute care (LTAC), and home. Transition points can be problematic if not addressed adequately; however, proactive planning can optimize patient care. Individual patient factors will determine if the patient will require long-term tracheostomy, transitioned to noninvasive positive pressure ventilation, or able to be decannulated. Patients and caregivers should be included in transition planning to optimize outcomes.

Individualized flow-controlled ventilation compared to best clinical practice pressure-controlled ventilation: a prospective randomized porcine study.

BACKGROUND: Flow-controlled ventilation is a novel ventilation method which allows to individualize ventilation according to dynamic lung mechanic limits based on direct tracheal pressure measurement at a stable constant gas flow during inspiration and expiration. The aim of this porcine study was to compare individualized flow-controlled ventilation (FCV) and current guideline-conform pressure-controlled ventilation (PCV) in long-term ventilation. METHODS: Anesthetized pigs were ventilated with either FCV or PCV over a period of 10 h with a fixed FiO2 of 0.3. FCV settings were individualized by compliance-guided positive end-expiratory pressure (PEEP) and peak pressure (Ppeak) titration. Flow was adjusted to maintain normocapnia and the inspiration to expiration ratio (I:E ratio) was set at 1:1. PCV was performed with a PEEP of 5 cm H2O and Ppeak was set to achieve a tidal volume (VT) of 7 ml/kg. The respiratory rate was adjusted to maintain normocapnia and the I:E ratio was set at 1:1.5. Repeated measurements during observation period were assessed by linear mixed-effects model. RESULTS: In FCV (n = 6), respiratory minute volume was significantly reduced (6.0 vs 12.7, MD - 6.8 (- 8.2 to - 5.4) l/min; p < 0.001) as compared to PCV (n = 6). Oxygenation was improved in the FCV group (paO2 119.8 vs 96.6, MD 23.2 (9.0 to 37.5) Torr; 15.97 vs 12.87, MD 3.10 (1.19 to 5.00) kPa; p = 0.010) and CO2 removal was more efficient (paCO2 40.1 vs 44.9, MD - 4.7 (- 7.4 to - 2.0) Torr; 5.35 vs 5.98, MD - 0.63 (- 0.99 to - 0.27) kPa; p = 0.006). Ppeak and driving pressure were comparable in both groups, whereas PEEP was significantly lower in FCV (p = 0.002). Computed tomography revealed a significant reduction in non-aerated lung tissue in individualized FCV (p = 0.026) and no significant difference in overdistended lung tissue, although a significantly higher VT was applied (8.2 vs 7.6, MD 0.7 (0.2 to 1.2) ml/kg; p = 0.025). CONCLUSION: Our long-term ventilation study demonstrates the applicability of a compliance-guided individualization of FCV settings, which resulted in significantly improved gas exchange and lung tissue aeration without signs of overinflation as compared to best clinical practice PCV.

Proportional assist ventilation versus pressure support ventilation for weaning from mechanical ventilation in adults: a meta-analysis and trial sequential analysis.

BACKGROUND: Pressure support ventilation (PSV) is the prevalent weaning method. Proportional assist ventilation (PAV) is an assisted ventilation mode, which is recently being applied to wean the patients from mechanical ventilation. Whether PAV or PSV is superior for weaning remains unclear. METHODS: Eligible randomized controlled trials published before April 2020 were retrieved from databases. We calculated the risk ratio (RR) and mean difference (MD) with 95% confidence intervals (CIs). RESULTS: Seven articles, involving 634 patients, met the selection criteria. Compared to PSV, PAV was associated with a significantly higher rate of weaning success (fixed-effect RR 1.16; 95% CI 1.07-1.26; I2 = 0.0%; trial sequential analysis-adjusted CI 1.03-1.30), and the trial sequential monitoring boundary for benefit was crossed. Compared to PSV, PAV was associated with a lower proportion of patients requiring reintubation (RR 0.49; 95% CI 0.28-0.87; I2 = 0%), a shorter ICU length of stay (MD - 1.58 (days), 95% CI - 2.68 to - 0.47; I2 = 0%), and a shorter mechanical ventilation duration (MD - 40.26 (hours); 95% CI - 66.67 to - 13.84; I2 = 0%). There was no significant difference between PAV and PSV with regard to mortality (RR 0.66; 95% CI 0.42-1.06; I2 = 0%) or weaning duration (MD - 0.01 (hours); 95% CI - 1.30-1.28; I2 = 0%). CONCLUSION: The results of the meta-analysis suggest that PAV is superior to PSV in terms of weaning success, and the statistical power is confirmed using trial sequential analysis.

Airway pressure morphology and respiratory muscle activity during end-inspiratory occlusions in pressure support ventilation.

BACKGROUND: The driving pressure of the respiratory system is a valuable indicator of global lung stress during passive mechanical ventilation. Monitoring lung stress in assisted ventilation is indispensable, but achieving passive conditions in spontaneously breathing patients to measure driving pressure is challenging. The accuracy of the morphology of airway pressure (Paw) during end-inspiratory occlusion to assure passive conditions during pressure support ventilation has not been examined. METHODS: Retrospective analysis of end-inspiratory occlusions obtained from critically ill patients during pressure support ventilation. Flow, airway, esophageal, gastric, and transdiaphragmatic pressures were analyzed. The rise of gastric pressure during occlusion with a constant/decreasing transdiaphragmatic pressure was used to identify and quantify the expiratory muscle activity. The Paw during occlusion was classified in three patterns, based on the differences at three pre-defined points after occlusion (0.3, 1, and 2 s): a "passive-like" decrease followed by plateau, a pattern with "clear plateau," and an "irregular rise" pattern, which included all cases of late or continuous increase, with or without plateau. RESULTS: Data from 40 patients and 227 occlusions were analyzed. Expiratory muscle activity during occlusion was identified in 79% of occlusions, and at all levels of assist. After classifying occlusions according to Paw pattern, expiratory muscle activity was identified in 52%, 67%, and 100% of cases of Paw of passive-like, clear plateau, or irregular rise pattern, respectively. The driving pressure was evaluated in the 133 occlusions having a passive-like or clear plateau pattern in Paw. An increase in gastric pressure was present in 46%, 62%, and 64% of cases at 0.3, 1, and 2 s, respectively, and it was greater than 2 cmH2O, in 10%, 20%, and 15% of cases at 0.3, 1, and 2 s, respectively. CONCLUSIONS: The pattern of Paw during an end-inspiratory occlusion in pressure support cannot assure the absence of expiratory muscle activity and accurate measurement of driving pressure. Yet, because driving pressure can only be overestimated due to expiratory muscle contraction, in everyday practice, a low driving pressure indicates an absence of global lung over-stretch. A measurement of high driving pressure should prompt further diagnostic workup, such as a measurement of esophageal pressure.

Are positive-pressure ventilation lobby rooms effective for protective and source isolation?

High-efficiency particulate air supplied to a positive-pressure ventilation lobby (PPVL) in isolation rooms offers the dual advantage of protective and source isolation. This study demonstrates the in-use validity of PPVL rooms for protective isolation of patients. Of the 48 PPVL air samples investigated, Aspergillus fumigatus was detected from only one (2%) sample. Local and remote monitoring of the PPVL rooms is essential for the safety of patients and healthcare workers. Remote and point-of-use engineering controls are essential for ongoing ventilation monitoring, but this should be complemented by visual inspection of the isolation suite. Periodic microbiological monitoring should also be considered with other control measures.

Ventilation Strategies in Severe Bronchopulmonary Dysplasia.

Bronchopulmonary dysplasia (BPD) is an acquired, developmental chronic lung disease that is a consequence of premature birth. In the most severe form of the disease, infants may require prolonged periods of positive pressure ventilation. BPD is a heterogeneous disease with lung mechanics that differ from those in respiratory distress syndrome; strategies to manage the respiratory support in infants with severe BPD should take this into consideration. When caring for these infants, practitioners need to shift from the acute care ventilation strategies that use frequent blood gases and support adjustments designed to minimize exposure to positive pressure. Infants with severe BPD benefit from a chronic care model that uses less frequent ventilator adjustments and provides the level of positive support that will achieve the longer-term goal of ongoing lung growth and repair.

Airway Occlusion Pressure As an Estimate of Respiratory Drive and Inspiratory Effort during Assisted Ventilation.

Rationale: Monitoring and controlling respiratory drive and effort may help to minimize lung and diaphragm injury. Airway occlusion pressure (P0.1) is a noninvasive measure of respiratory drive.Objectives: To determine 1) the validity of "ventilator" P0.1 (P0.1vent) displayed on the screen as a measure of drive, 2) the ability of P0.1 to detect potentially injurious levels of effort, and 3) how P0.1vent displayed by different ventilators compares to a "reference" P0.1 (P0.1ref) measured from airway pressure recording during an occlusion.Methods: Analysis of three studies in patients, one in healthy subjects, under assisted ventilation, and a bench study with six ventilators. P0.1vent was validated against measures of drive (electrical activity of the diaphragm and muscular pressure over time) and P0.1ref. Performance of P0.1ref and P0.1vent to detect predefined potentially injurious effort was tested using derivation and validation datasets using esophageal pressure-time product as the reference standard.Measurements and Main Results: P0.1vent correlated well with measures of drive and with the esophageal pressure-time product (within-subjects R2 = 0.8). P0.1ref >3.5 cm H2O was 80% sensitive and 77% specific for detecting high effort (≥200 cm H2O ⋅ s ⋅ min-1); P0.1ref ≤1.0 cm H2O was 100% sensitive and 92% specific for low effort (≤50 cm H2O ⋅ s ⋅ min-1). The area under the receiver operating characteristics curve for P0.1vent to detect potentially high and low effort were 0.81 and 0.92, respectively. Bench experiments showed a low mean bias for P0.1vent compared with P0.1ref for most ventilators but precision varied; in patients, precision was lower. Ventilators estimating P0.1vent without occlusions could underestimate P0.1ref.Conclusions: P0.1 is a reliable bedside tool to assess respiratory drive and detect potentially injurious inspiratory effort.

Suboptimal heart rate assessment and airway management in infants receiving delivery room chest compressions: a quality assurance project.

OBJECTIVE: In a previous audit, we demonstrated poor compliance with the neonatal resuscitation algorithm. Training can improve guideline compliance and performance. We aimed to prospectively collect detailed data on delivery room resuscitations to identify needs for educational interventions. DESIGN: Observational study using video recordings of neonatal resuscitations. We analysed episodes where chest compressions (CCs) were provided. SETTING: A Norwegian university hospital. PATIENTS: All delivery room resuscitations August 2014 to November 2016. INTERVENTIONS: The recordings were transcribed using Interact V.9 software (Mangold Int GmbH, Arnstorf, Germany). Supplementary information was collected from the patient electronic records. MAIN OUTCOME MEASURES: Heart rate (HR) assessment, provision of positive pressure ventilation (PPV) and CC, endotracheal intubation and team communication. RESULTS: Twenty-nine CC episodes were analysed. We identified team discordance in the decisions to perform CC and only 6 (21%) were retrospectively judged to be in need for CC: 8 (28%) infants had adequate spontaneous respiration, 18 (62%) infants received ineffective PPV and 5 (17%) had a HR >60 bpm. Only one infant was intubated before CC, and we could not identify a consistent pattern of ventilation corrective actions. One infant received CC without prior HR assessment. In some infants, CC duration was exceedingly short, and 11 (38%) of the infants that received CC were not admitted to the NICU. Six (21%) infants had no documentation of CPR in the delivery record. CONCLUSIONS: Education and training should focus on team function and communication, correct and timely HR assessment, effective PPV, and indications for endotracheal intubation.

Static and Dynamic Transpulmonary Driving Pressures Affect Lung and Diaphragm Injury during Pressure-controlled versus Pressure-support Ventilation in Experimental Mild Lung Injury in Rats.

BACKGROUND: Pressure-support ventilation may worsen lung damage due to increased dynamic transpulmonary driving pressure. The authors hypothesized that, at the same tidal volume (VT) and dynamic transpulmonary driving pressure, pressure-support and pressure-controlled ventilation would yield comparable lung damage in mild lung injury. METHODS: Male Wistar rats received endotoxin intratracheally and, after 24 h, were ventilated in pressure-support mode. Rats were then randomized to 2 h of pressure-controlled ventilation with VT, dynamic transpulmonary driving pressure, dynamic transpulmonary driving pressure, and inspiratory time similar to those of pressure-support ventilation. The primary outcome was the difference in dynamic transpulmonary driving pressure between pressure-support and pressure-controlled ventilation at similar VT; secondary outcomes were lung and diaphragm damage. RESULTS: At VT = 6 ml/kg, dynamic transpulmonary driving pressure was higher in pressure-support than pressure-controlled ventilation (12.0 ± 2.2 vs. 8.0 ± 1.8 cm H2O), whereas static transpulmonary driving pressure did not differ (6.7 ± 0.6 vs. 7.0 ± 0.3 cm H2O). Diffuse alveolar damage score and gene expression of markers associated with lung inflammation (interleukin-6), alveolar-stretch (amphiregulin), epithelial cell damage (club cell protein 16), and fibrogenesis (metalloproteinase-9 and type III procollagen), as well as diaphragm inflammation (tumor necrosis factor-α) and proteolysis (muscle RING-finger-1) were comparable between groups. At similar dynamic transpulmonary driving pressure, as well as dynamic transpulmonary driving pressure and inspiratory time, pressure-controlled ventilation increased VT, static transpulmonary driving pressure, diffuse alveolar damage score, and gene expression of markers of lung inflammation, alveolar stretch, fibrogenesis, diaphragm inflammation, and proteolysis compared to pressure-support ventilation. CONCLUSIONS: In the mild lung injury model use herein, at the same VT, pressure-support compared to pressure-controlled ventilation did not affect biologic markers. However, pressure-support ventilation was associated with a major difference between static and dynamic transpulmonary driving pressure; when the same dynamic transpulmonary driving pressure and inspiratory time were used for pressure-controlled ventilation, greater lung and diaphragm injury occurred compared to pressure-support ventilation.