Flow-Limited and Reverse-Triggered Ventilator Dyssynchrony Are Associated With Increased Tidal and Dynamic Transpulmonary Pressure

OBJECTIVES

Ventilator dyssynchrony may be associated with increased delivered tidal volumes (V t s) and dynamic transpulmonary pressure (ΔP L,dyn ), surrogate markers of lung stress and strain, despite low V t ventilation. However, it is unknown which types of ventilator dyssynchrony are most likely to increase these metrics or if specific ventilation or sedation strategies can mitigate this potential.

DESIGN

A prospective cohort analysis to delineate the association between ten types of breaths and delivered V t , ΔP L,dyn , and transpulmonary mechanical energy.

SETTING

Patients admitted to the medical ICU.

PATIENTS

Over 580,000 breaths from 35 patients with acute respiratory distress syndrome (ARDS) or ARDS risk factors.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Patients received continuous esophageal manometry. Ventilator dyssynchrony was identified using a machine learning algorithm. Mixed-effect models predicted V t , ΔP L,dyn , and transpulmonary mechanical energy for each type of ventilator dyssynchrony while controlling for repeated measures. Finally, we described how V t , positive end-expiratory pressure (PEEP), and sedation (Richmond Agitation-Sedation Scale) strategies modify ventilator dyssynchrony's association with these surrogate markers of lung stress and strain. Double-triggered breaths were associated with the most significant increase in V t , ΔP L,dyn , and transpulmonary mechanical energy. However, flow-limited, early reverse-triggered, and early ventilator-terminated breaths were also associated with significant increases in V t , ΔP L,dyn , and energy. The potential of a ventilator dyssynchrony type to increase V t , ΔP L,dyn , or energy clustered similarly. Increasing set V t may be associated with a disproportionate increase in high-volume and high-energy ventilation from double-triggered breaths, but PEEP and sedation do not clinically modify the interaction between ventilator dyssynchrony and surrogate markers of lung stress and strain.

CONCLUSIONS

Double-triggered, flow-limited, early reverse-triggered, and early ventilator-terminated breaths are associated with increases in V t , ΔP L,dyn , and energy. As flow-limited breaths are more than twice as common as double-triggered breaths, further work is needed to determine the interaction of ventilator dyssynchrony frequency to cause clinically meaningful changes in patient outcomes.

Hospital Outcomes in Patients Who Developed Acute Respiratory Distress Syndrome After Community-Acquired Pneumonia

Purpose: To identify risk factors for and outcomes in acute respiratory distress syndrome (ARDS) in patients hospitalized with community-acquired pneumonia (CAP). Methods: This is a retrospective study using the Premier Healthcare Database between 2016 and 2020. Patients diagnosed with pneumonia, requiring mechanical ventilation (MV), antimicrobial therapy, and hospital admission ≥2 days were included. Multivariable regression models were used for outcomes including in-hospital mortality, hospital length of stay (LOS), intensive care unit (ICU) LOS, and days on MV. Results: 1924 (2.7%) of 72 107 patients with CAP developed ARDS. ARDS was associated with higher mortality (33.7% vs 18.9%; adjusted odds ratio 2.4; 95% confidence interval [CI] 2.16-2.66), longer hospital LOS (13 vs 9 days; adjusted incidence risk ratio (aIRR) 1.24; 95% CI 1.20-1.27), ICU LOS (9 vs 5 days; aIRR 1.51; 95% CI 1.46-1.56), more MV days (8 vs 5; aIRR 1.54; 95% CI 1.48-1.59), and increased hospitalization cost ($46 459 vs $29 441; aIRR 1.50; 95% CI 1.45-1.55). Conclusion: In CAP, ARDS was associated with worse in-patient outcomes in terms of mortality, LOS, and hospitalization cost. Future studies are needed to explore outcomes in patients with CAP with ARDS and explore risk factors for development of ARDS after CAP.

Novel Method for Sealing Tracheostomies Immediately after Decannulation-An Acute Clinical Feasibility Study

Tracheostomy decannulation leaves an iatrogenic passage in the upper airways. Inadequate sealing leads to pulmonary dysfunction and reduced voice quality. This study aimed to investigate the feasibility and impact of intratracheal tracheostomy sealing on laryngeal airflow and voice quality immediately after decannulation (ClinicalTrials.gov: NCT06138093). Fifteen adult, tracheostomized, intensive care unit patients were included from our hospital. A temporary, silicone-based sealing disc was inserted in the tracheostomy wound immediately after decannulation. Spirometry with measurement of forced vital capacity (FVC), forced expiratory volume in the first second (FEV1), and peak expiratory flow (PEF) were performed as measures of airway flow. Voice recordings were assessed using an equal appearing interval scale from 1 to 5. Median FVC, FEV1, PEF, and voice quality score with interquartile range (IQR) was 883 (510-1910) vs. 1260 (1005-1723) mL (p < 0.001), 790 (465-1255) vs. 870 (617-1297) mL (p < 0.001), 103 (55-211) vs. 107 (62-173) mL (p = 0.720), and 2 (1-2.5) vs. 4 (3-5) points (p < 0.001), respectively, with open tracheostomy vs. after sealing the tracheostomy with the intratracheal sealing disc. This feasibility study showed that tracheostomy sealing with the intratracheal disc was safe and led to immediate improvements in FVC, FEV1, and voice quality.

Association between mechanical power and intensive care unit mortality in Korean patients under pressure-controlled ventilation

BACKGROUND

Mechanical power (MP) has been reported to be associated with clinical outcomes. Because the original MP equation is derived from paralyzed patients under volume-controlled ventilation, its application in practice could be limited in patients receiving pressure-controlled ventilation (PCV). Recently, a simplified equation for patients under PCV was developed. We investigated the association between MP and intensive care unit (ICU) mortality.

METHODS

We conducted a retrospective analysis of Korean data from the Fourth International Study of Mechanical Ventilation. We extracted data of patients under PCV on day 1 and calculated MP using the following simplified equation: MPPCV = 0.098 ∙ respiratory rate ∙ tidal volume ∙ (ΔPinsp + positive end-expiratory pressure), where ΔPinsp is the change in airway pressure during inspiration. Patients were divided into survivors and non-survivors and then compared. Multivariable logistic regression was performed to determine association between MPPCV and ICU mortality. The interaction of MPPCV and use of neuromuscular blocking agent (NMBA) was also analyzed.

RESULTS

A total of 125 patients was eligible for final analysis, of whom 38 died in the ICU. MPPCV was higher in non-survivors (17.6 vs. 26.3 J/min, P<0.001). In logistic regression analysis, only MPPCV was significantly associated with ICU mortality (odds ratio, 1.090; 95% confidence interval, 1.029-1.155; P=0.003). There was no significant effect of the interaction between MPPCV and use of NMBA on ICU mortality (P=0.579).

CONCLUSIONS

MPPCV is associated with ICU mortality in patients mechanically ventilated with PCV mode, regardless of NMBA use.

Factors related to lung function outcomes in critically ill COVID-19 patients in South Korea

BACKGROUND

New variants of the virus responsible for the coronavirus disease 2019 (COVID-19) pandemic continue to emerge. However, little is known about the effect of these variants on clinical outcomes. This study evaluated the risk factors for poor pulmonary lung function test (PFT).

METHODS

The study retrospectively analyzed 87 patients in a single hospital and followed up by performing PFTs at an outpatient clinic from January 2020 to December 2021. COVID-19 variants were categorized as either a non-delta variant (November 13, 2020-July 6, 2021) or the delta variant (July 7, 2021-January 29, 2022).

RESULTS

The median age of the patients was 62 years, and 56 patients (64.4%) were male. Mechanical ventilation (MV) was provided for 52 patients, and 36 (41.4%) had restrictive lung defects. Forced vital capacity (FVC) and diffusion capacity of the lung for carbon monoxide (DLCO ) were lower in patients on MV. Male sex (odds ratio [OR], 0.228) and MV (OR, 4.663) were significant factors for decreased DLCO . The duration of MV was associated with decreased FVC and DLCO . However, the type of variant did not affect the decrease in FVC (P=0.750) and DLCO (P=0.639).

CONCLUSIONS

Among critically ill COVID-19 patients, 40% had restrictive patterns with decreased DLCO . The reduction of PFT was associated with MV, type of variants.

Effect of additional dead space using end-tidal CO2 measurement on ventilating preterm infants: An experimental study

BACKGROUND

Dead space is the part of the airway where no gas exchange takes place. Any increase in dead space volume has a proportional effect on the required tidal volume and thus on the risk of ventilation-induced lung injury. Inserts that increase dead space are therefore not used in small preterm infants. This includes end-tidal CO2 measurement.

OBJECTIVE

The aim of this study was to investigate the effect of the end-tidal CO2 measurement adapter on ventilation.

METHODS

In an experimental setup, an end-tidal CO2 measurement adapter, three different pneumotachographs (PNT-A, PNT-B, PNT-Neo), and a closed suction adapter were combined in varying set-ups. The time required for CO2 elimination by a CO2-flooded preterm infant test lung was measured.

RESULTS

PNT-A prolonged CO2 elimination time by 0.9 s (+3.3%), Neo-PNT by 3.2 s (+11.6%) and PNT-B by 9.0 s (+32.7%). The end-tidal CO2 measurement adapter prolonged the elimination time by an additional second without the pneumotachograph (+3.6%) and in combination with PNT-A (+3.1%) and PNT-Neo (+3.1%). In conjunction with PNT-B, the end-tidal CO2 measurement adapter reduced the elimination time by 0.3 seconds (-1%). The use of a closed suction adaptor increased the CO2 elimination time by a further second with PNT-Neo (+3.1%) and by an additional two seconds with no flow sensor (+6.9%), with PNT-A (+6.4%) and with PNT-B (+5.5%).

CONCLUSION

The flow sensor had the greatest influence on ventilatory effort, while end-tidal CO2 measurement had only a moderate effect. The increased ventilatory effort levied by the CO2 measurement was dependent on the flow sensor selected. The use of closed suctioning more negatively impacted ventilatory effort than did end-tidal CO2 measurement.

Effect of fourth hourly oropharyngeal suctioning on ventilator-associated events in patients requiring mechanical ventilation in intensive care units of a tertiary care center in South India: a randomized controlled trial

BACKGROUND

Mechanical ventilation (MV) is a necessary life-saving measure for critically ill patients. Ventilator-associated events (VAEs) are potentially avoidable complications associated with MV that can double the rate of death. Oral care and oropharyngeal suctioning, although neglected procedures, play a vital role in the prevention of VAE.

METHODS

A randomized controlled trial was conducted in the intensive care units to compare the effect of fourth hourly oropharyngeal suctioning with the standard oral care protocol on VAE among patients on MV. One hundred twenty mechanically ventilated patients who were freshly intubated and expected to be on ventilator support for the next 72 hours were randomly allocated to the control or intervention groups. The intervention was fourth hourly oropharyngeal suctioning along with the standard oral care procedure. The control group received standard oral care (i.e., thrice a day) and on-demand oral suctioning. On the 3rd and 7th days following the intervention, endotracheal aspirates were sent to rule out ventilator-associated pneumonia.

RESULTS

Both groups were homogenous at baseline with respect to their clinical characteristics. The intervention group had fewer VAEs (56.7%) than the control group (78.3%) which was significant at P<0.01. A significant reduction in the status of "positive culture" on ET aspirate also been observed following the 3rd day of the intervention (P<0.001).

CONCLUSIONS

One of the most basic preventive strategies is providing oral care. Oropharyngeal suctioning is also an important component of oral care that prevents microaspiration. Hence, fourth-hourly oropharyngeal suctioning with standard oral care significantly reduces the incidence of VAE.

Exploring factors affecting the timely transition of ventilator assisted individuals in Ontario from acute to long-term care: Perspectives of healthcare professionals

Rationale

Ventilator Assisted Individuals (VAIs) frequently remain in intensive care units (ICUs) for a prolonged period once clinically stable due to a lack of transition options. These VAIs occupy ICU beds and resources that patients with more acute needs could better utilize. Moreover, VAIs experience improved outcomes and quality of life in long-term and community-based environments.

Objective

To better understand the perspectives of healthcare providers (HCPs) working in an Ontario ICU regarding barriers and facilitators to referral and transition of VAIs from the ICU to a long-term setting.

Methods

We conducted semi-structured interviews with ten healthcare providers involved in VAI transitions.

Main Results

Perceived barriers included long wait times for long-term care settings, insufficient bed availability at discharge locations, medical complexity of patients, long waitlists, and a lack of transparency of waitlists. Facilitators included strong partnerships and trusting relationships between referring and discharge locations, a centralized referral system, and utilization of community partnerships across care sectors.

Conclusions

Insufficient resourcing of long-term care is a key barrier to transitioning VAIs from ICU to long-term settings; strong partnerships across care sectors are a facilitator. System-level approaches, such as a single-streamlined referral system, are needed to address key barriers to timely transition.

Disparities in Adult Patient Selection for Extracorporeal Membrane Oxygenation in the United States: A Population-Level Study

Rationale: Disparities in patient selection for advanced therapeutics in health care have been identified in multiple studies, but it is unclear if disparities exist in patient selection for extracorporeal membrane oxygenation (ECMO), a rapidly expanding critical care resource. Objectives: To determine if disparities exist in patient selection for ECMO based on sex, primary insurance, and median income of the patient's neighborhood. Methods: In a retrospective cohort study using the Nationwide Readmissions Database 2016-2019, we identified patients treated with mechanical ventilation (MV) and/or ECMO with billing codes. Patient sex, insurance, and income level for patients receiving ECMO were compared with the patients treated with MV only, and hierarchical logistic regression with the hospital as a random intercept was used to determine odds of receiving ECMO based on patient demographics. Results: We identified 2,170,752 MV hospitalizations with 18,725 cases of ECMO. Among patients treated with ECMO, 36.1% were female compared with 44.5% of patients treated with> MV only (adjusted odds ratio [aOR] for ECMO, 0.73; 95% confidence interval [CI], 0.70-0.75). Of patients treated with ECMO, 38.1% had private insurance compared with 17.4% of patients treated with MV only. Patients with Medicaid were less likely to receive ECMO than patients with private insurance (aOR, 0.55; 95% CI, 0.52-0.57). Patients treated with ECMO were more likely to live in the highest-income neighborhoods compared with patients treated with MV only (25.1% vs. 17.3%). Patients living in the lowest-income neighborhoods were less likely to receive ECMO than those living in the highest-income neighborhoods (aOR, 0.63; 95% CI, 0.60-0.67). Conclusions: Significant disparities exist in patient selection for ECMO. Female patients, patients with Medicaid, and patients living in the lowest-income neighborhoods are less likely to be treated with ECMO. Despite possible unmeasured confounding, these findings were robust to multiple sensitivity analyses. On the basis of previous work describing disparities in other areas of health care, we speculate that limited access in some neighborhoods, restrictive/biased interhospital transfer practices, differences in patient preferences, and implicit provider bias may contribute to the observed differences. Future studies with more granular data are needed to identify and modify drivers of observed disparities.

Longitudinal trajectories of sedation level and clinical outcomes in patients who are mechanically ventilated based on a group-based trajectory model: a prospective, multicentre, longitudinal and observational study in Korea

OBJECTIVES

Changes in sedation levels over a long time in patients who are mechanically ventilated are unknown. Therefore, we investigated the long-term sedation levels of these patients by classifying them into different longitudinal patterns.

DESIGN

This was a multicentre, prospective, longitudinal, and observational study.

SETTING

Twenty intensive care units (ICUs) spanning several medical institutions in Korea.

PARTICIPANTS

Patients who received mechanical ventilation and sedatives in ICU within 48 hours of admission between April 2020 and July 2021.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary objective of this study was to identify the pattern of sedation practice. Additionally, we analysed the associations of trajectory groups with clinical outcomes as the secondary outcome.

RESULTS

Sedation depth was monitored using Richmond Agitation-Sedation Scale (RASS). A group-based trajectory model was used to classify 631 patients into four trajectories based on sedation depth: persistent suboptimal (13.2%, RASS ≤ -3 throughout the first 30 days), delayed lightening (13.9%, RASS ≥ -2 after the first 15 days), early lightening (38.4%, RASS ≥ -2 after the first 7 days) and persistent optimal (34.6%, RASS ≥ -2 during the first 30 days). 'Persistent suboptimal' trajectory was associated with delayed extubation (HR: 0.23, 95% CI: 0.16 to 0.32, p<0.001), longer ICU stay (HR: 0.36, 95% CI: 0.26 to 0.51, p<0.001) and hospital mortality (HR: 13.62, 95% CI: 5.99 to 30.95, p<0.001) compared with 'persistent optimal'. The 'delayed lightening' and 'early lightening' trajectories showed lower extubation probability (HR: 0.30, 95% CI: 0.23 to 0.41, p<0.001; HR: 0.72, 95% CI: 0.59 to 0.87, p<0.001, respectively) and ICU discharge (HR: 0.44, 95% CI: 0.33 to 0.59, p<0.001 and HR: 0.80, 95% CI: 0.65 to 0.97, p=0.024) compared with 'persistently optimal'.

CONCLUSIONS

Among the four trajectories, 'persistent suboptimal' trajectory was associated with higher mortality.

Mechanical Ventilation in ARDS With an Automatic Resuscitator

BACKGROUND

The Oxylator is an automatic resuscitator, powered only by an oxygen cylinder with no electricity required, that could be used in acute respiratory failure in situations in which standard mechanical ventilation is not available or feasible. We aimed to assess the feasibility and safety of mechanical ventilation by using this automatic resuscitator in an animal model of ARDS.

METHODS

A randomized experimental study in a porcine ARDS model with 12 pigs randomized to the Oxylator group or the control group (6 per group) and ventilated for 4 h. In the Oxylator group, peak pressure was set at 20 cm H2O and PEEP was set at the lowest observed breathing frequency during a decremental PEEP titration. The control pigs were ventilated with a conventional ventilator by using protective settings and PEEP at the crossing point of collapse and overdistention, as indicated by electrical impedance tomography. Our end points were feasibility and safety as well as respiratory mechanics, gas exchange, and hemodynamics.

RESULTS

After lung injury, the mean ± SD respiratory system compliance and PaO2 /FIO2 were 13 ± 2 mL/cm H2O and 61 ± 17 mm Hg, respectively. The mean ± SD total PEEP was 10 ± 2 cm H2O and 13 ± 2 cm H2O in the control and Oxylator groups, respectively (P = .046). The mean plateau pressure was kept to < 30 cm H2O in both groups. In the Oxylator group, the tidal volume was transiently > 8 mL/kg but was 6 ± 0.4 mL/kg at 4 h, whereas the breathing frequency increased from 38 ± 4 to 48 ± 3 breaths/min (P < .001). There was no difference in driving pressure, compliance, PaO2 /FIO2 , and pulmonary shunt between the groups. The mean ± SD PaCO2 was higher in the Oxylator group after 4 h, 74 ± 9 mm Hg versus 58 ± 6 mm Hg (P < .001). There were no differences in hemodynamics between the groups, including blood pressure and cardiac output.

CONCLUSIONS

Short-term mechanical ventilation by using an automatic resuscitator and a fixed pressure setting in an ARDS animal model was feasible and safe.

Infection-Related Ventilator-Associated Complications in Critically Ill Patients with Trauma: A Retrospective Analysis

BACKGROUND

Trauma is a leading cause of death and disability. Patients with trauma undergoing invasive mechanical ventilation (IMV) are at risk for ventilator-associated events (VAEs) potentially associated with a longer duration of IMV and increased stay in the intensive care unit (ICU).

METHODS

We conducted a retrospective cohort study aimed to evaluate the incidence of infection-related ventilator-associated complications (IVACs), possible ventilator-associated pneumonia (PVAP), and their characteristics among patients experiencing severe trauma that required ICU admission and IMV for at least four days. We also determined pathogens implicated in PVAP episodes and characterized the use of antimicrobial therapy.

RESULTS

In total, 88 adult patients were included in the main analysis. In this study, we observed that 29.5% of patients developed a respiratory infection during ICU stay. Among them, five patients (19.2%) suffered from respiratory infections due to multi-drug resistant bacteria. Patients who developed IVAC/PVAP presented lower total GCS (median value, 7; (IQR, 9) vs. 12.5, (IQR, 8); p = 0.068) than those who did not develop IVAC/PVAP.

CONCLUSIONS

We observed that less than one-third of trauma patients fulfilling criteria for ventilator associated events developed a respiratory infection during the ICU stay.

Executive Summary: International Clinical Practice Guidelines for Pediatric Ventilator Liberation, A Pediatric Acute Lung Injury and Sepsis Investigators (PALISI) Network Document

Rationale: Pediatric-specific ventilator liberation guidelines are lacking despite the many studies exploring elements of extubation readiness testing. The lack of clinical practice guidelines has led to significant and unnecessary variation in methods used to assess pediatric patients' readiness for extubation. Methods: Twenty-six international experts comprised a multiprofessional panel to establish pediatrics-specific ventilator liberation clinical practice guidelines, focusing on acutely hospitalized children receiving invasive mechanical ventilation for more than 24 hours. Eleven key questions were identified and first prioritized using the Modified Convergence of Opinion on Recommendations and Evidence. A systematic review was conducted for questions that did not meet an a priori threshold of ⩾80% agreement, with Grading of Recommendations, Assessment, Development, and Evaluation methodologies applied to develop the guidelines. The panel evaluated the evidence and drafted and voted on the recommendations. Measurements and Main Results: Three questions related to systematic screening using an extubation readiness testing bundle and a spontaneous breathing trial as part of the bundle met Modified Convergence of Opinion on Recommendations criteria of ⩾80% agreement. For the remaining eight questions, five systematic reviews yielded 12 recommendations related to the methods and duration of spontaneous breathing trials, measures of respiratory muscle strength, assessment of risk of postextubation upper airway obstruction and its prevention, use of postextubation noninvasive respiratory support, and sedation. Most recommendations were conditional and based on low to very low certainty of evidence. Conclusions: This clinical practice guideline provides a conceptual framework with evidence-based recommendations for best practices related to pediatric ventilator liberation.

Challenging Diagnosis of a Congenital Tracheal Malformation: Considerations From an Intensive Care Perspective

Congenital tracheal stenosis is a rare airway malformation. A high index of suspicion is fundamental. The authors report a case of congenital tracheal stenosis in a 13-month-old male infant, with a challenging diagnosis from the intensive care perspective. At birth, the patient presented an anorectal malformation with a recto-urethral fistula so a colostomy with mucous fistula was performed in the neonatal period. At the age of seven months, he was admitted due to a respiratory infection, treated with steroids and bronchodilators, and discharged after three days without any complications. He underwent complete repair of tetralogy of Fallot when he was 11 months old, which was performed without any reported perioperative complications. However, at the age of 13 months, due to another respiratory infection, he presented more severe symptoms and required admission to the pediatric intensive care unit (PICU) for invasive mechanical ventilation. He was intubated on the first attempt. While monitoring the difference between peak inspiratory and plateau pressures, we observed a sustained elevated difference between pressures suggestive of increased airway resistance, thus raising the possibility of an anatomical obstruction. Laryngotracheoscopy confirmed distal tracheal stenosis (grade II) with four complete tracheal rings. In our case, the absences of perioperative challenges or complications in previous respiratory infections were not suggestive of a tracheal malformation. Furthermore, no difficulties were encountered during intubation due to the distal location of the tracheal stenosis. A careful appreciation of respiratory mechanics on the ventilator at rest and during tracheal aspirations was essential to suspect an anatomical defect.

Diaphragm Neurostimulation Mitigates Ventilation-Associated Brain Injury in a Preclinical Acute Respiratory Distress Syndrome Model

In a porcine healthy lung model, temporary transvenous diaphragm neurostimulation (TTDN) for 50 hours mitigated hippocampal apoptosis and inflammation associated with mechanical ventilation (MV).

HYPOTHESIS

Explore whether TTDN in combination with MV for 12 hours mitigates hippocampal apoptosis and inflammation in an acute respiratory distress syndrome (ARDS) preclinical model.

METHODS AND MODELS

Compare hippocampal apoptosis, inflammatory markers, and serum markers of neurologic injury between never ventilated subjects and three groups of mechanically ventilated subjects with injured lungs: MV only (LI-MV), MV plus TTDN every other breath, and MV plus TTDN every breath. MV settings in volume control were tidal volume 8 mL/kg and positive end-expiratory pressure 5 cm H₂O. Lung injury, equivalent to moderate ARDS, was achieved by infusing oleic acid into the pulmonary artery.

RESULTS

Hippocampal apoptosis, microglia, and reactive-astrocyte percentages were similar between the TTDN-every-breath and never ventilated groups. The LI-MV group had a higher percentage of these measures than all other groups (p < 0.05). Transpulmonary driving pressure at study end was lower in the TTDN-every-breath group than in the LI-MV group; systemic inflammation and lung injury scores were not significantly different. The TTDN-every-breath group had considerably lower serum concentration of homovanillic acid (cerebral dopamine production surrogate) at study end than the LI-MV group (p < 0.05). Heart rate variability declined in the LI-MV group and increased in both TTDN groups (p < 0.05).

INTERPRETATIONS AND CONCLUSIONS

In a moderate-ARDS porcine model, MV is associated with hippocampal apoptosis and inflammation, and TTDN mitigates that hippocampal apoptosis and inflammation.

COVID-19: dealing with ventilator shortage

PURPOSE OF REVIEW

To describe different strategies adopted during coronavirus disease 2019 pandemic to cope with the shortage of mechanical ventilators.

RECENT FINDINGS

Short-term interventions aimed to increase ventilator supply and decrease demand. They included: redistributing and centralizing patients, repurposing operating rooms into intensive care units (ICUs) and boosting ventilator production and using stocks and back-ups; support by the critical care outreach team to optimize treatment of patients in the ward and permit early discharge from the ICU, ethical allocation of mechanical ventilators to patients who could benefit more from intensive treatment and short term ICU trials for selected patients with uncertain prognosis, respectively. Long-term strategies included education and training of non-ICU physicians and nurses to the care of critically-ill patients and measures to decrease viral spread among the population and the progression from mild to severe disease.

SUMMARY

The experience and evidence gained during the current pandemic is of paramount importance for physicians and law-makers to plan in advance an appropriate response to any future similar crisis. Intensive care unit, hospital, national and international policies can all be improved to build systems capable of treating an unexpectedly large number of patients, while keeping a high standard of safety.

Outcomes of Early Versus Late Tracheostomy in Patients With COVID-19: A Multinational Cohort Study

Timing of tracheostomy in patients with COVID-19 has attracted substantial attention. Initial guidelines recommended delaying or avoiding tracheostomy due to the potential for particle aerosolization and theoretical risk to providers. However, early tracheostomy could improve patient outcomes and alleviate resource shortages. This study compares outcomes in a diverse population of hospitalized COVID-19 patients who underwent tracheostomy either "early" (within 14 d of intubation) or "late" (more than 14 d after intubation).

DESIGN

International multi-institute retrospective cohort study.

SETTING

Thirteen hospitals in Bolivia, Brazil, Spain, and the United States.

PATIENTS

Hospitalized patients with COVID-19 undergoing early or late tracheostomy between March 1, 2020, and March 31, 2021.

INTERVENTIONS

Not applicable.

MEASUREMENTS AND MAIN RESULTS

A total of 549 patients from 13 hospitals in four countries were included in the final analysis. Multivariable regression analysis showed that early tracheostomy was associated with a 12-day decrease in time on mechanical ventilation (95% CI, -16 to -8; p < 0.001). Further, ICU and hospital lengths of stay in patients undergoing early tracheostomy were 15 days (95% CI, -23 to -9 d; p < 0.001) and 22 days (95% CI, -31 to -12 d) shorter, respectively. In contrast, early tracheostomy patients experienced lower risk-adjusted survival at 30-day post-admission (hazard ratio, 3.0; 95% CI, 1.8-5.2). Differences in 90-day post-admission survival were not identified.

CONCLUSIONS

COVID-19 patients undergoing tracheostomy within 14 days of intubation have reduced ventilator dependence as well as reduced lengths of stay. However, early tracheostomy patients experienced lower 30-day survival. Future efforts should identify patients most likely to benefit from early tracheostomy while accounting for location-specific capacity.

A Constructivist Grounded Theory of Staff Experiences Relating to Early Mobilisation of Mechanically Ventilated Patients in Intensive Care

Early mobilisation of mechanically ventilated patients has been suggested to be effective in mitigating muscle weakness, yet it is not a common practice. Understanding staff experiences is crucial to gain insights into what might facilitate or hinder its implementation. In this constructivist grounded theory study, data from two Scottish intensive care units were collected to understand healthcare staff experiences relating to early mobilisation in mechanical ventilation. Data included observations of mobilisation activities, individual staff interviews and two focus groups with multidisciplinary staff. Managing Risks emerged as the core category and was theorised using the concept of risk. The middle-range theory developed in this study suggests that the process of early mobilisation starts by staff defining patient status and includes a process of negotiating patient safety, which in turn enables performing accountable mobilisation within the dynamic context of an intensive care unit setting.

Turning any bed into an intensive care unit with the Internet of things and artificial intelligence technology. Presenting the enhanced mechanical ventilator

The recent Coronavirus disease 2019 (COVID-19) pandemic displayed weaknesses in the healthcare infrastructures worldwide and exposed a lack of specialized personnel to cover the demands of a massive calamity. We have developed a portable ventilator that uses real-time vitals read from the patient to estimate -- through artificial intelligence -- the optimal operation point. The ventilator has redundant telecommunication capabilities; therefore, the remote assistance model can protect specialists and relatives from highly contagious agents. Additionally, we have designed a system that automatically publishes information in a proprietary cloud centralizer to keep physicians and relatives informed. The system was tested in a residential last-mile connection, and transaction times below the second were registered. The timing scheme allows us to operate up to 200 devices concurrently on these lowest-specification transmission control protocol/internet protocol (TCP/IP) services, promptly transmitting data for online processing and reporting. The ventilator is a proof of concept of automation that has behavioral and cognitive inputs to cheaply, yet reliably, extend the installed capacity of the healthcare systems and multiply the response of the skilled medical personnel to cover high-demanding scenarios and improve service quality.

Public Opinion on Priorities Toward Fair Allocation of Ventilators During COVID-19 Pandemic: A Nationwide Survey

Background: The rapidly growing imbalance between supply and demand for ventilators during the COVID-19 pandemic has highlighted the principles for fair allocation of scarce resources. Failing to address public views and concerns on the subject could fuel distrust. The objective of this study was to determine the priorities of the Iranian public toward the fair allocation of ventilators during the COVID-19 pandemic. Methods: This anonymous community-based national study was conducted from May 28 to Aug 20, 2020, in Iran. Data were collected via the Google Forms platform, using an online self-administrative questionnaire. The questionnaire assessed participants' assigned prioritization scores for ventilators based on medical and non-medical criteria. To quantify participants' responses on prioritizing ventilator allocation among sub-groups of patients with COVID-19 who need mechanical ventilation scores ranging from -2, very low priority, to +2, very high priority were assigned to each response. Results: Responses of 2,043 participants, 1,189 women, and 1,012 men, were analyzed. The mean (SD) age was 31.1 (9.5), being 32.1 (9.3) among women, and 29.9 (9.6) among men. Among all participants, 274 (13.4%) were healthcare workers. The median of assigned priority score was zero (equal) for gender, age 41-80, nationality, religion, socioeconomic, high-profile governmental position, high-profile occupation, being celebrities, employment status, smoking status, drug abuse, end-stage status, and obesity. The median assigned priority score was +2 (very high priority) for pregnancy, and having <2 years old children. The median assigned priority score was +1 (high priority) for physicians and nurses of patients with COVID-19, patients with nobel research position, those aged <40 years, those with underlying disease, immunocompromise status, and malignancy. Age>80 was the only factor participants assigned -1 (low priority) to. Conclusions: Participants stated that socioeconomic factors, except for age>80, should not be involved in prioritizing mechanical ventilators at the time of resources scarcity. Front-line physicians and nurses of COVID-19 patients, pregnant mothers, mothers who had children under 2 years old were given high priority.

Long-Term Mortality in Critically Ill Tracheostomized Patients Based on Home Mechanical Ventilation at Discharge

Data regarding the long-term outcomes for tracheostomized patients receiving home mechanical ventilation (HMV) are limited. We aimed to determine the 1-year mortality rate for critically ill tracheostomized patients with and without HMV. Data of tracheostomized patients between 1 January 2015 and 31 December 2019 were analyzed. A Kaplan-Meier analysis was performed to assess the survival curve of the patients. Among the 124 tracheostomized patients, 102 (82.3%) were weaned from mechanical ventilation (MV), and 22 (17.7%) required HMV at discharge. The overall 1-year mortality rate was 47.6%, and HMV group had a significantly higher 1-year mortality rate than those weaned from MV (41.2% vs. 77.3%, p = 0.002). In the Cox proportional hazards regression, BMI (HR 0.913 [95% CI 0.850-0.980], p = 0.012), Sequential Organ Failure Assessment (SOFA) score (HR 1.114 [95% CI 1.040-1.193], p = 0.002), transfer to a nursing facility (HR 5.055 [95% CI 1.558-16.400], p = 0.007), and HMV at discharge (HR 1.930 [95% CI 1.082-3.444], p = 0.026) were significantly associated with 1-year mortality. Critically ill tracheostomized patients with HMV at discharge had a significantly higher 1-year mortality rate than those weaned from MV. Low BMI, high SOFA score, transfer to a nursing facility, and HMV at discharge were significantly associated with 1-year mortality.

Calculated Plasma Volume Status Is Associated With Mortality in Acute Respiratory Distress Syndrome

Supplemental Digital Content is available in the text.

The optimal method to assess fluid overload in acute respiratory distress syndrome is not known, and current techniques have limitations. Plasma volume status has emerged as a noninvasive method to assess volume status and is defined as the percentage alteration from ideal plasma volume. We hypothesized that plasma volume status would suggest the presence of significant excess volume and therefore correlate with mortality in acute respiratory distress syndrome.

Development and Implementation of a Multicomponent Protocol to Promote Sleep and Reduce Delirium in a Medical Intensive Care Unit

BACKGROUND

Evidence suggests that poor sleep increases risk of delirium. Because delirium is associated with poor outcomes, institutions have developed protocols to improve sleep in critically ill patients.

OBJECTIVE

To assess the impact of implementing a multicomponent sleep protocol.

METHODS

In this prospective, preimplementation and postimplementation evaluation, adult patients admitted to the medical intensive care unit (ICU) over 42 days were included. Outcomes evaluated included median delirium-free days, median Richards-Campbell Sleep Questionnaire (RCSQ) score, median optimal sleep nights, duration of mechanical ventilation (MV), ICU and hospital length of stay (LOS), and in-hospital mortality.

RESULTS

The preimplementation group included 78 patients and postimplementation group, 84 patients. There was no difference in median delirium-free days (1 day [interquartile range, IQR, = 0-2.5] vs 1 day [IQR = 0-2]; P = 0.48), median RCSQ score (59.4 [IQR = 43.2-71.6] vs 61.2 [IQR = 49.9-75.5]; P = 0.20), median optimal sleep nights (1 night [IQR = 0-2] vs 1 night [IQR = 0-2]; P = 0.95), and in-hospital mortality (16.7% vs 17.9%, P = 1.00). Duration of MV (8 days [IQR = 4-10] vs 4 days [IQR = 2-7]; P = 0.03) and hospital LOS (13 days [IQR = 7-22.3] vs 8 days [IQR = 6-17]; P = 0.05) were shorter in the postimplementation group, but both were similar between groups after adjusting for age and severity of illness.

CONCLUSIONS AND RELEVANCE

This report demonstrates that implementation of a multicomponent sleep protocol in everyday ICU care is feasible, but limitations exist when evaluating impact on measurable outcomes. Additional evaluations are needed to identify the most meaningful interventions and best practices for quantifying impact on patient outcomes.

Role of ventilator and nasal interface in pressure transmission during neonatal intermittent positive pressure ventilation: A bench study

We aimed at evaluating pressure transmission and stability during non-synchronized neonatal nasal intermittent positive pressure ventilation (NIPPV) delivered using five mechanical ventilators and three nasal interfaces. An artificial nose-throat model was connected to a mechanical analog of the infant respiratory system and a breath generator. Ventilation was administrated via a nasal mask (NM), short bi-nasal prongs (SBN), or RAM® cannula. We applied positive end-expiratory pressures (PEEP) of 5 and 10 cmH₂ O, inspiratory pressures (PIP) of 15 and 30 cmH₂ O, inspiratory times of 0.23, 0.42, and 0.57 s. Measurements were performed with leaks of 0, 1.5, and 4 L/min. The pressure was measured at the airways opening (P_AW ) and the glottis (P_GL ). The difference between set and delivered pressures (P_AW ) was less than ±1 cmH₂ O for all ventilators. We documented a significant difference between P_AW and P_GL in the presence of leaks. With 4 L/min leaks, PEEP dropped by 43%, 49%, and 63% with NM, SBP, and RAM® cannula, respectively; PIP dropped by 58%, 64%, and 74%. On average, the SD of PEEP fluctuations was ±0.60 and ±2.50 cmH₂ O for P_AW and P_GL ; the breath-by-breath SD of PIP was ±0.77 and ±2.06 cmH₂ O. During NIPPV, the PIP and PEEP transmission to the glottis is markedly lower than the set values and highly variable. The impact of leaks and nasal interface is much more significant than the differences in ventilators' performance on the efficacy of pressure transmission and stability of non-synchronized ventilator-generated NIPPV.

Delivery of Inhaled Nitric Oxide During MRI to Ventilated Neonates and Infants

BACKGROUND

Many pediatric and neonatal ICU patients receive nitric oxide (NO), with some also requiring magnetic resonance imaging (MRI) scans. MRI-compatible NO delivery devices are not always available. We describe and bench test a method of delivering NO during MRI using standard equipment in which a NO delivery device was positioned in the MRI control room with the NO blender component connected to oxygen and set to 80 ppm and delivering flow via 12 m of tubing to a MRI-compatible ventilator, set up inside the MRI scanner magnet room.

METHODS

For our bench test, the ventilator was set up normally and connected to an infant test lung to simulate several patients of differing weight (ie, 4 kg, 10 kg, 20 kg). The NO blender delivered flows of 2-10 L/min to the ventilator to achieve a range of NO and oxygen concentrations monitored via extended tubing. The measured values were compared to calculated values.

RESULTS

A range of NO concentrations (12-41 ppm) and F_IO2 values (0.67-0.97) were achieved during the bench testing. The additional flow increased delivered peak inspiratory pressure and PEEP by 1-5 cm H₂O. Calculated values were within acceptable ranges and were used to create a lookup table.

CONCLUSIONS

In clinical use, this system can safely generate a range of NO flows of 15-42 ppm with an accompanying F_IO2 range of 0.34-0.98.

Real-Time In Vitro Assessment of Aerosol Delivery During Mechanical Ventilation

Background: A new real-time method for assessing factors determining aerosol delivery is described.

Methods: A breath-enhanced jet nebulizer operated in a ventilator/heated humidifier system was tested during bolus and continuous infusion aerosol delivery. ^99mTc (technetium)/saline was either injected (3 or 6 mL) or infused over time into the nebulizer. A shielded gamma ratemeter was oriented to count radioaerosol accumulating on an inhaled mass (IM) filter at the airway opening of a test lung. Radioactivity measured at 2–10-minute intervals was expressed as % nebulizer charge (bolus) or % syringe activity per minute infused. All circuit parts were measured and imaged by gamma camera to determine mass balance.

Results: Ratemeter activity quantitatively reflected immediate changes in IM: 3 and 6 mL bolus IM% = 16.1 and 18.8% in 6 and 14 minutes, respectively; infusion IM% = 0.64 + 0.13 (run time, min), R² 0.999. Effect of nebulizer priming and system anomalies were readily detected in real time. Mass balance (basis = dose infused in 90 minutes): IM 39.2%, breath-enhanced jet nebulizer residual 35.5%, circuit parts including humidifier 23.4%, and total recovery 98.1%. Visual analysis of circuit component images identified sites of increased deposition.

Conclusion: Real-time ratemeter measurement with gamma camera imaging provides operational feedback during in vitro testing procedures and yields a detailed analysis of the parameters influencing drug delivery during mechanical ventilation. This method of analysis facilitates assessment of device function and influence of circuit parameters on drug delivery.

Outcomes of acute respiratory distress syndrome in COVID-19 patients compared to the general population: a systematic review and meta-analysis

INTRODUCTION

Acute respiratory distress syndrome (ARDS) due to coronavirus disease 2019 (COVID-19) often leads to mortality. Outcomes of patients with COVID-19-related ARDS compared to ARDS unrelated to COVID-19 is not well characterized.

AREAS COVERED

We performed a systematic review of PubMed, Scopus, and MedRxiv 11/1/2019 to 3/1/2021, including studies comparing outcomes in COVID-19-related ARDS (COVID-19 group) and ARDS unrelated to COVID-19 (ARDS group). Outcomes investigated were duration of mechanical ventilation-free days, intensive care unit (ICU) length-of-stay (LOS), hospital LOS, and mortality. Random effects models were fit for each outcome measure. Effect sizes were reported as pooled median differences of medians (MDMs), mean differences (MDs), or odds ratios (ORs).

EXPERT OPINION

Ten studies with 2,281 patients met inclusion criteria (COVID-19: 861 [37.7%], ARDS: 1420 [62.3%]). There were no significant differences between the COVID-19 and ARDS groups for median number of mechanical ventilator-free days (MDM: -7.0 [95% CI: -14.8; 0.7], p = 0.075), ICU LOS (MD: 3.1 [95% CI: -5.9; 12.1], p = 0.501), hospital LOS (MD: 2.5 [95% CI: -5.6; 10.7], p = 0.542), or all-cause mortality (OR: 1.25 [95% CI: 0.78; 1.99], p = 0.361). Compared to the general ARDS population, results did not suggest worse outcomes in COVID-19-related ARDS.

Titration of Parameters in Shared Ventilation With a Portable Ventilator

BACKGROUND

Dual-patient, single-ventilator protocols (ie, protocols to ventilate 2 patients with a single conventional ventilator) may be required in times of crisis. This study demonstrates a means to titrate peak inspiratory pressure (PIP), PEEP, and [Formula: see text] for test lungs ventilated via a dual-patient, single-ventilator circuit.

METHODS

This prospective observational study was conducted using a ventilator connected to 2 test lungs. Changes in PIP, PEEP, and [Formula: see text] were made to the experimental lung, while no changes were made to the control lung. Measurements were obtained simultaneously from each test lung. PIP was titrated using 3D-printed resistors added to the inspiratory circuit. PEEP was titrated using expiratory circuit tubing with an attached manual PEEP valve. [Formula: see text] was titrated by using a splitter added to the ventilator tubing.

RESULTS

PIP, PEEP, and [Formula: see text] were reliably and incrementally titratable in the experimental lung, with some notable but manageable changes in pressure and [Formula: see text] documented in the control lung during these titrations. Similar results were measured in lungs with identical and different compliances.

CONCLUSIONS

Pressures and [Formula: see text] can be reliably adjusted when utilizing a dual-patient, single-ventilator circuit with simple, low-cost modifications to the circuit. This innovation could potentially be lifesaving in a resource-limited or crisis setting. Understanding the interactions of these circuits is imperative for making their use safer.

Factors Determining Continuous Infusion Aerosol Delivery During Mechanical Ventilation

BACKGROUND

Continuous nebulization of prostacyclins and albuterol by infusion pump during mechanical ventilation evolved as a popular off-label treatment for severe hypoxemic respiratory failure and asthma. Most institutions use a vibrating mesh nebulizer. A new breath-enhanced jet nebulizer is a potential alternative. This study was designed to compare these devices to better define factors influencing continuous infusion aerosol delivery. Device function, ventilator settings, and infusion pump flow were studied in vitro.

METHODS

Using a bench model of adult mechanical ventilation, radiolabeled saline was infused at 6 flows (1.5-12 mL/h) into test nebulizers; 4 examples of each were used in rotation to test device reproducibility. Four breathing patterns with duty cycles (percentage of inspiratory time) ranging from 0.13 to 0.34 were tested. The vibrating mesh nebulizer was installed on the "dry" side of the heated humidifier (37°C). The breath-enhanced jet nebulizer, installed on the "wet" side, was powered by air at 3.5 L/min and 50 psi. Infusion time was 1 h. Inhaled mass of aerosol was collected on a filter at the airway opening. Inhaled mass was expressed as the percentage of the initial syringe radioactivity delivered per hour. Radioactivity deposited in the circuit was measured with a gamma camera. Data were analyzed with multiple linear regression.

RESULTS

Variation in inhaled mass was significantly explained by pump flow and duty cycle (R² 0.92) and not by nebulizer technology. Duty cycle effects were more apparent at higher pump flow. Vibrating mesh nebulizers failed to nebulize completely in 20% of the test runs. Mass balance indicated that vibrating mesh nebulizers deposited 15.3% in the humidifier versus 0.2% for breath-enhanced jet nebulizer.

CONCLUSIONS

Aerosol delivery was determined by infusion pump flow and ventilator settings with comparable aerosol delivery between devices. The breath-enhanced jet nebulizer was more reliable than the vibrating mesh nebulizer; 10-12 mL/h was the maximum infusion flow for both nebulizer technologies.

Cardiovascular Disease and Severe Hypoxemia Are Associated With Higher Rates of Noninvasive Respiratory Support Failure in Coronavirus Disease 2019 Pneumonia

Supplemental Digital Content is available in the text.

Objectives:

Acute hypoxemic respiratory failure is the major complication of coronavirus disease 2019, yet optimal respiratory support strategies are uncertain. We aimed to describe outcomes with high-flow oxygen delivered through nasal cannula and noninvasive positive pressure ventilation in coronavirus disease 2019 acute hypoxemic respiratory failure and identify individual factors associated with noninvasive respiratory support failure.

Design:

Retrospective cohort study to describe rates of high-flow oxygen delivered through nasal cannula and/or noninvasive positive pressure ventilation success (live discharge without endotracheal intubation). Fine-Gray subdistribution hazard models were used to identify patient characteristics associated with high-flow oxygen delivered through nasal cannula and/or noninvasive positive pressure ventilation failure (endotracheal intubation and/or in-hospital mortality).

Setting:

One large academic health system, including five hospitals (one quaternary referral center, a tertiary hospital, and three community hospitals), in New York City.

Patients:

All hospitalized adults 18–100 years old with coronavirus disease 2019 admitted between March 1, 2020, and April 28, 2020.

Interventions:

None.

Measurements and Main Results:

A total of 331 and 747 patients received high-flow oxygen delivered through nasal cannula and noninvasive positive pressure ventilation as the highest level of noninvasive respiratory support, respectively; 154 (46.5%) in the high-flow oxygen delivered through nasal cannula cohort and 167 (22.4%) in the noninvasive positive pressure ventilation cohort were successfully discharged without requiring endotracheal intubation. In adjusted models, significantly increased risk of high-flow oxygen delivered through nasal cannula and noninvasive positive pressure ventilation failure was seen among patients with cardiovascular disease (subdistribution hazard ratio, 1.82; 95% CI, 1.17–2.83 and subdistribution hazard ratio, 1.40; 95% CI, 1.06–1.84, respectively). Conversely, a higher peripheral blood oxygen saturation to Fio₂ ratio at high-flow oxygen delivered through nasal cannula and noninvasive positive pressure ventilation initiation was associated with reduced risk of failure (subdistribution hazard ratio, 0.32; 95% CI, 0.19–0.54, and subdistribution hazard ratio 0.34; 95% CI, 0.21–0.55, respectively).

Conclusions:

A significant proportion of patients receiving noninvasive respiratory modalities for coronavirus disease 2019 acute hypoxemic respiratory failure achieved successful hospital discharge without requiring endotracheal intubation, with lower success rates among those with comorbid cardiovascular disease or more severe hypoxemia. The role of high-flow oxygen delivered through nasal cannula and noninvasive positive pressure ventilation in coronavirus disease 2019–related acute hypoxemic respiratory failure warrants further consideration.

Development of a prognostic scoring system in patients with pneumonia requiring ventilator care for more than 4 days: a single-center observational study

BACKGROUND

The aim of the present study was to develop a prognostic model using demographic characteristics, comorbidities, and clinical variables measured on day 4 of mechanical ventilation (MV) for patients with prolonged acute mechanical ventilation (PAMV; MV for >96 hours).

METHODS

Data from 437 patients (70.9% male; median age, 68 years) were obtained over a period of 9 years. All patients were diagnosed with pneumonia. Binary logistic regression identified factors predicting mortality at 90 days after the start of MV. A PAMV prognosis score was calculating ß-coefficient values and assigning points to variables.

RESULTS

The overall 90-day mortality rate was 47.1%. Five factors (age ≥65 years, body mass index <18.5 kg/m2, hemato-oncologic diseases as comorbidities, requirement for vasopressors on day 4 of MV and requirement for neuromuscular blocking agents on day 4 of MV) were identified as prognostic indicators. Each factor was valued as +1 point, and used to develop a PAMV prognosis score. This score showed acceptable discrimination (area under the receiver operating characteristic curve of 0.695 for mortality, 95% confidence interval 0.650-0.738, p<0.001), and calibration (Hosmer-Lemeshow chi-square=6.331, with df 7 and p=0.502). The cutoff value for predicting mortality based on the maximum Youden index was ≤2 (sensitivity, 87.5%; specificity, 41.3%). For patients with PAMV scores ≤1, 2, 3 and ≥4, the 90-day mortality rates were 29.2%, 45.7%, 67.9%, and 90.9%, respectively (P<0.001).

CONCLUSIONS

Our study developed a PAMV prognosis score for predicting 90-day mortality. Further research is needed to validate the utility of this score.

The Association Between Ventilatory Ratio and Mortality in Children and Young Adults

BACKGROUND

The ventilatory ratio (VR) is a dead-space marker associated with mortality in mechanically ventilated adults with ARDS. The end-tidal alveolar dead space fraction (AVDSf) has been associated with mortality in children. However, AVDSf requires capnography measurements, whereas VR does not. We sought to examine the prognostic value of VR, in comparison to AVDSf, in children and young adults with acute hypoxemic respiratory failure.

METHODS

We conducted a retrospective study of prospectively collected data from 180 mechanically ventilated children and young adults with acute hypoxemic respiratory failure. VR was calculated as (minute ventilation × [Formula: see text])/(age-adjusted predicted minute ventilation × 37.5). AVDSf was calculated as [Formula: see text].

RESULTS

VR and AVDSf had a moderate correlation (rho 0.31, P < .001). VR was similar between survivors at 1.22 (interquartile range [IQR] 1.0-1.52) and nonsurvivors at 1.30 (IQR 0.96-1.95) (P = .2). AVDSf was lower in survivors at 0.12 (IQR 0.03-0.23) than nonsurvivors at 0.24 (IQR 0.13-0.33) (P < .001). In logistic regression and competing risk regression analyses, VR was not associated with mortality or rate of extubation at any given time (competing risk death; all P > .3). An AVDSf in the highest 2 quartiles, in comparison to the lowest quartile (AVDSf < 0.06), was associated with higher mortality after adjustment for oxygenation index and severity of illness (AVDSf ≥ 0.15-0.26: odds ratio 3.58, 95% CI 1.02-12.64, P = .047, and AVDSf ≥ 0.26: odds ratio 3.91 95% CI-1.03-14.83, P = .045). At any given time after intubation, a child with an AVDSf ≥ 0.26 was less likely to be extubated than a child with an AVDSf < 0.06, after adjustment for oxygenation index and severity of illness (AVDSf ≥ 0.26: subdistribution hazard ratio 0.55, 95% CI 0.33-0.94, P = .03).

CONCLUSIONS

VR should not be used for prognostic purposes in children and young adults. AVDSf added prognostic information to the severity of oxygenation defect and overall severity of illness in children and young adults, consistent with previous research.

Evaluation of Respiratory Therapist Extender Comfort With Mechanical Ventilation During COVID-19 Pandemic

BACKGROUND

Staffing strategies used to meet the needs of respiratory care departments during the COVID-19 pandemic included the deployment of respiratory therapist extenders. The purpose of this study was to evaluate respiratory therapist extenders' comfort level with critical care ventilators while caring for patients with COVID-19. To our knowledge, this is the first study to evaluate the deployment of certified registered nurse anesthetists (CRNAs) in a critical care setting.

METHODS

A qualitative survey method was used to assess CRNA experience with critical care ventilators. Prior to deployment in the ICU, CRNAs were trained by clinical lead respiratory therapists. Education included respiratory clinical practices and ventilator management. Sixty-minute sessions were held with demonstration stations set up in ICUs for hands-on experience.

RESULTS

Fifty-six CRNAs responded to our survey (63%). A mean ± SD of 9.48 ± 12.27 h was spent training prior to deployment in the ICU. CRNAs were at the bedside a mean ± SD of 73.0 ± 40.6 h during the pandemic. While CRNA comfort level with critical care ventilators increased significantly (P < .001) from the beginning to the end of their work experience, no statistically significant differences were found between CRNA comfort based on years of experience. Differences in comfort level were not found after training (chi-squared test 23.82, P = .09) or after ICU experience was completed (chi-squared test = 15.99, P = .45). Similarly, mean comfort level did not increase based on the number of hours spent working in the ICU (chi-squared test = 13.67, P = .55).

CONCLUSIONS

Comfort level with mechanical ventilation increased for CRNAs working alongside respiratory therapists during the COVID-19 pandemic.

Human factors/ergonomics to support the design and testing of rapidly manufactured ventilators in the UK during the COVID-19 pandemic

Background

This paper describes a rapid response project from the Chartered Institute of Ergonomics & Human Factors (CIEHF) to support the design, development, usability testing and operation of new ventilators as part of the UK response during the COVID-19 pandemic.

Method

A five-step approach was taken to (1) assess the COVID-19 situation and decide to formulate a response; (2) mobilise and coordinate Human Factors/Ergonomics (HFE) specialists; (3) ideate, with HFE specialists collaborating to identify, analyse the issues and opportunities, and develop strategies, plans and processes; (4) generate outputs and solutions; and (5) respond to the COVID-19 situation via targeted support and guidance.

Results

The response for the rapidly manufactured ventilator systems (RMVS) has been used to influence both strategy and practice to address concerns about changing safety standards and the detailed design procedure with RMVS manufacturers.

Conclusion

The documents are part of a wider collection of HFE advice which is available on the CIEHF COVID-19 website (https://covid19.ergonomics.org.uk/).

Noninvasive Ventilation Use in Critically Ill Patients with Acute Asthma Exacerbations

Rationale: Noninvasive ventilation decreases the need for invasive mechanical ventilation and mortality among patients with chronic obstructive pulmonary disease but has not been well studied in asthma.Objectives: To assess the association between noninvasive ventilation and subsequent need for invasive mechanical ventilation and in-hospital mortality among patients admitted with asthma exacerbation to the ICU.Methods: We performed a retrospective cohort study using administrative data collected during 2010-2017 from 682 hospitals in the United States. Outcomes included receipt of invasive mechanical ventilation and in-hospital mortality. Generalized estimating equations, propensity-matched models, and marginal structural models were used to assess the association between noninvasive ventilation and outcomes.Measurements and Main Results: The study population included 53,654 participants with asthma exacerbation. During the study period, 13,540 patients received noninvasive ventilation (25.2%; 95% confidence interval [CI], 24.9-25.6%), 14,498 underwent invasive mechanical ventilation (27.0%; 95% CI, 26.7-27.4%), and 1,291 died (2.4%; 95% CI, 2.3-2.5%). Among those receiving noninvasive ventilation, 3,013 patients (22.3%; 95% CI, 21.6-23.0%) required invasive mechanical ventilation after first receiving noninvasive ventilation, 136 of whom died (4.5%; 95% CI, 3.8-5.3%). Across all models, the use of noninvasive ventilation was associated with a lower odds of receiving invasive mechanical ventilation (adjusted generalized estimating equation odds ratio, 0.36; 95% CI, 0.32-0.40) and in-hospital mortality (odds ratio, 0.48; 95% CI 0.40-0.58). Those who received noninvasive ventilation before invasive mechanical ventilation were more likely to have comorbid pneumonia and severe sepsis.Conclusions: Noninvasive ventilation use during asthma exacerbation was associated with improved outcomes but should be used cautiously with acute comorbid conditions.

Clinical outcomes of difficult-to-wean patients with ventilator dependency at intensive care unit discharge

Background

Ventilator-dependent patients in the intensive care unit (ICU) who are difficult to wean from invasive mechanical ventilation (IMV) have been increasing in number. However, data on the clinical outcomes of difficult-to-wean patients are lacking. We aimed to evaluate clinical outcomes in patients discharged from the ICU with tracheostomy and ventilator dependency.

Methods

We retrospectively investigated clinical course and survival in patients requiring home mechanical ventilation (HMV) with a tracheostomy and difficulty weaning from IMV during medical ICU admission from September 2013 through August 2016 at Severance Hospital, Yonsei University, Seoul, Korea.

Results

Of 84 difficult-to-wean patients who were started on HMV in the medical ICU, 72 survived, were discharged from the ICU, and were included in this analysis. HMV was initiated after a median of 23 days of IMV, and the successful weaning rate was 46% (n=33). In-hospital mortality rate was significantly lower in the successfully weaned group than the unsuccessfully weaned group (0% vs. 23.1%, respectively; P=0.010). Weaning rates were similar according to primary diagnosis, but high body mass index (BMI), low Acute Physiologic Assessment and Chronic Health Evaluation (APACHE) II score at ICU admission, and absence of neuromuscular disease were associated with weaning success. After a median follow-up of 4.6 months (range, 1–27 months) for survivors, 3-month (n=64) and 6-month (n=59) survival rates were 82.5% and 72.2%, respectively. Survival rates were higher in the successfully weaned group than the unsuccessfully weaned group at 3 months (96.4% vs. 69.0%; P=0.017) and 6 months (84.0% vs. 62.1%; P=0.136) following ICU discharge.

Conclusions

In summary, 46% of patients who started HMV were successfully weaned from the ventilator in general wards. High BMI, low APACHE II score, and absence of neuromuscular disease were factors associated with weaning success.

The Ventilator Management Team: Repurposing Anesthesia Workstations and Personnel to Combat COVID-19

The coronavirus disease 2019 pandemic resulted in unprecedented numbers of patients with respiratory failure requiring ventilatory support. The number of patients who required critical care quickly outpaced the availability of intensive care unit (ICU) beds. Consequently, health care systems had to creatively expand critical care services into alternative hospital locations with repurposed staff and equipment. Deploying anesthesia workstations to the ICU to serve as mechanical ventilators requires equipment preparation, multidisciplinary planning, and targeted education. We aim to contextualize this process, highlighting major differences between anesthesia workstations and ICU ventilators, and to share the insights gained from our experiences creating an anesthesia provider-based ventilator management team.

Changes in Attitudes and Actual Practice of Oxygen Therapy in ICUs after Implementation of a Conservative Oxygenation Guideline

BACKGROUND

Little is known to what extent attitudes of ICU clinicians are influenced by new insights and recommendations to be more conservative with oxygen therapy. Our aim was to investigate whether implementation of a conservative oxygenation guideline structurally changed self-reported attitudes and actual clinical practice.

METHODS

After the implementation of a conservative oxygen therapy guideline in 3 teaching hospitals in the Netherlands, ICU clinicians were surveyed regarding their attitudes toward oxygen therapy. The survey results were compared with survey results taken before the introduction of the new guideline. Arterial blood gas analysis data and ventilator settings were retrieved from all patients admitted to the participating ICUs in the studied period, and changes after implementing the guideline were assessed.

RESULTS

In total, 180 ICU clinicians returned the survey. Compared to before implementation of a conservative oxygen guideline, more clinicians chose a preferred [Formula: see text] and an oxygen saturation measured from an arterial sample ([Formula: see text]) limit after implementation of the guideline. In general, clinicians reported a more conservative approach toward management of [Formula: see text] and less frequently increased the [Formula: see text]. In the period after the active implementation of the guideline, 5,840 subjects were admitted to the participating ICUs and 101,869 arterial blood gas analyses were retrieved. Actual practice changed with overall lower oxygenation levels (median [Formula: see text] 77.93 mm Hg, compared to 86.93 mm Hg before implementation) of arterial blood and a decrease of PEEP and [Formula: see text].

CONCLUSIONS

Implementing a conservative oxygenation guideline was an effective method that changed self-reported attitudes and actual clinical practice and improved adherence to conservative oxygenation targets in a short period of time.

Clinical features and outcomes associated with tracheostomy in congenital diaphragmatic hernia

INTRODUCTION

The purpose of this study was to examine the clinical features/outcomes associated with tracheostomy in infants with congenital diaphragmatic hernia (CDH).

METHODS

The study population consisted of liveborn infants reported to the CDH Study Group registry between 2007 and 2017. Subjects were identified as having a tracheostomy if they were discharged or transferred to another hospital with tracheostomy and/or on mechanical ventilation. Multivariate mixed models were used for analyses.

RESULTS

The registry population consisted of 5434 subjects, of whom 230 (4.2%) underwent tracheostomy placement. Only 3830 (70.5%) infants survived until discharge/transfer. The median age of tracheostomy placement was 3.3 months (range, 1.3-13.4 when known; n = 58 out of 154 survivors). The mortality rate among subjects with tracheostomy was 32.8% with a median of 37 days (range, 8-189 when known; n = 32 out of 75 deceased) ensuing between tracheostomy placement and death. The clinical features found to be associated with increased odds ratio of tracheostomy placement included male sex, birth weight, 5-minute APGAR score, defect size, liver in chest, ECMO use, cardiac abnormality, other congenital abnormalities, pulmonary hypertension, and the presence of a feeding tube. There was center variation in the rate of tracheostomy placement, which may be partially accounted for by disease severity, but not center size.

CONCLUSION

There are several clinical features that are associated with increased likelihood of tracheostomy placement. Most deaths in subjects with tracheostomies occurred outside the immediate postoperative period. The utility of a standardized protocol for tracheostomy in infants with CDH should be considered.

An Observational Study of the Efficacy of Cisatracurium Compared with Vecuronium in Patients with or at Risk for Acute Respiratory Distress Syndrome

RATIONALE

The neuromuscular blocking agent cisatracurium may improve mortality for patients with moderate-to-severe acute respiratory distress syndrome (ARDS). Other neuromuscular blocking agents, such as vecuronium, are commonly used and have different mechanisms of action, side effects, cost, and availability in the setting of drug shortages.

OBJECTIVES

To determine whether cisatracurium is associated with improved outcomes when compared with vecuronium in patients at risk for and with ARDS.

METHODS

Using a nationally representative database, patients who were admitted to the ICU with a diagnosis of ARDS or an ARDS risk factor, received mechanical ventilation, and were treated with a continuous infusion of neuromuscular blocking agent for at least 2 days within 2 days of hospital admission were included. Patients were stratified into two groups: those who received cisatracurium or vecuronium. Propensity matching was used to balance both patient- and hospital-specific factors. Outcomes included hospital mortality, duration of mechanical ventilation, ICU and hospital duration, and discharge location.

MEASUREMENTS AND MAIN RESULTS

Propensity matching successfully balanced all covariates for 3,802 patients (1,901 per group). There was no significant difference in mortality (odds ratio, 0.932; P = 0.40) or hospital days (-0.66 d; P = 0.411) between groups. However, patients treated with cisatracurium had fewer ventilator days (-1.01 d; P = 0.005) and ICU days (-0.98 d; P = 0.028) but were equally likely to be discharged home (odds ratio, 1.19; P = 0.056).

CONCLUSIONS

When compared with vecuronium, cisatracurium was not associated with a difference in mortality but was associated with improvements in other clinically important outcomes. These data suggest that cisatracurium may be the preferred neuromuscular blocking agent for patients at risk for and with ARDS.

Estimated effects of early diuretic use in critical illness

Supplemental Digital Content is available in the text.

Objectives:

To estimate the effects of diuretic use during the first 24 hours of an ICU stay on in-hospital mortality and other clinical outcomes including acute kidney injury and duration of mechanical ventilation.

Design:

Retrospective cohort study.

Setting:

Urban, academic medical center.

Patients:

Adult patients admitted to medical or cardiac ICUs between 2001 and 2012, excluding those on maintenance dialysis or with ICU length of stay less than 24 hours.

Interventions:

None.

Measurements and Main Results:

We included 13,589 patients: 2,606 with and 10,983 without early diuretic use (loop diuretic exposure during the first 24 hr of an ICU stay). Propensity score matching generated 2,523 pairs with well-balanced baseline characteristics. Early diuretic use was unassociated with in-hospital mortality (risk ratio, 1.01; 99.5% CI, 0.83–1.22). We found no evidence of associations with ICU or hospital length of stay, or duration or provision of mechanical ventilation. Early diuretic use was associated with higher rates of subsequent acute kidney injury (risk ratio, 1.41; 99.5% CI, 1.25–1.59) and electrolyte abnormalities. Results were not materially different in subgroups of patients with heart failure, chronic kidney disease, or acute lung injury.

Conclusions:

Early diuretic use in critical illness was unassociated with in-hospital mortality, ICU or hospital length of stay, or duration of mechanical ventilation, but risks of acute kidney injury and electrolyte abnormalities were higher.

Alternative Modes of Mechanical Ventilation

Modern mechanical ventilators are more complex than those first developed in the 1950s. Newer ventilation modes can be difficult to understand and implement clinically, although they provide more treatment options than traditional modes. These newer modes, which can be considered alternative or nontraditional, generally are classified as either volume controlled or pressure controlled. Dual-control modes incorporate qualities of pressure-controlled and volume-controlled modes. Some ventilation modes provide variable ventilatory support depending on patient effort and may be classified as closed-loop ventilation modes. Alternative modes of ventilation are tools for lung protection, alveolar recruitment, and ventilator liberation. Understanding the function and application of these alternative modes prior to implementation is essential and is most beneficial for the patient.

A Novel Picture Guide to Improve Spiritual Care and Reduce Anxiety in Mechanically Ventilated Adults in the Intensive Care Unit

RATIONALE

Hospital chaplains provide spiritual care that helps patients facing serious illness cope with their symptoms and prognosis, yet because mechanically ventilated patients cannot speak, spiritual care of these patients has been limited.

OBJECTIVES

To determine the feasibility and measure the effects of chaplain-led picture-guided spiritual care for mechanically ventilated adults in the intensive care unit (ICU).

METHODS

We conducted a quasi-experimental study at a tertiary care hospital between March 2014 and July 2015. Fifty mechanically ventilated adults in medical or surgical ICUs without delirium or dementia received spiritual care by a hospital chaplain using an illustrated communication card to assess their spiritual affiliations, emotions, and needs and were followed until hospital discharge. Feasibility was assessed as the proportion of participants able to identify spiritual affiliations, emotions, and needs using the card. Among the first 25 participants, we performed semistructured interviews with 8 ICU survivors to identify how spiritual care helped them. For the subsequent 25 participants, we measured anxiety (on 100-mm visual analog scales [VAS]) immediately before and after the first chaplain visit, and we performed semistructured interviews with 18 ICU survivors with added measurements of pain and stress (on ±100-mm VAS).

MEASUREMENTS AND MAIN RESULTS

The mean (SD) age was 59 (±16) years, median mechanical ventilation days was 19.5 (interquartile range, 7-29 d), and 15 (30%) died in-hospital. Using the card, 50 (100%) identified a spiritual affiliation, 47 (94%) identified one or more emotions, 45 (90%) rated their spiritual pain, and 36 (72%) selected a chaplain intervention. Anxiety after the first visit decreased 31% (mean score change, -20; 95% confidence interval, -33 to -7). Among 28 ICU survivors, 26 (93%) remembered the intervention and underwent semistructured interviews, of whom 81% felt more capable of dealing with their hospitalization and 0% felt worse. The 18 ICU survivors who underwent additional VAS testing during semistructured follow-up interviews reported a 49-point reduction in stress (95% confidence interval, -72 to -24) and no significant change in physical pain that they attributed to picture-guided spiritual care.

CONCLUSIONS

Chaplain-led picture-guided spiritual care is feasible among mechanically ventilated adults and shows potential for reducing anxiety during and stress after an ICU admission.

Testing of mechanical ventilators and infant incubators in healthcare institutions

The medical device industry has grown rapidly and incessantly over the past century. The sophistication and complexity of the designed instrumentation is nowadays rising and, with it, has also increased the need to develop some better, more effective and efficient maintenance processes, as part of the safety and performance requirements. This paper presents the results of performance tests conducted on 50 mechanical ventilators and 50 infant incubators used in various public healthcare institutions. Testing was conducted in accordance to safety and performance requirements stated in relevant international standards, directives and legal metrology policies. Testing of output parameters for mechanical ventilators was performed in 4 measuring points while testing of output parameters for infant incubators was performed in 7 measuring points for each infant incubator. As performance criteria, relative error of output parameters for mechanical ventilators and absolute error of output parameters for infant incubators was calculated. The ranges of permissible error, for both groups of devices, are regulated by the Rules on Metrological and Technical Requirements published in the Official Gazette of Bosnia and Herzegovina No. 75/14, which are defined based on international recommendations, standards and guidelines. All ventilators and incubators were tested by etalons calibrated in an ISO 17025 accredited laboratory, which provides compliance to international standards for all measured parameters.The results show that 30% of the tested medical devices are not operating properly and should be serviced, recalibrated and/or removed from daily application.

Influences of Duration of Inspiratory Effort, Respiratory Mechanics, and Ventilator Type on Asynchrony With Pressure Support and Proportional Assist Ventilation

BACKGROUND

Pressure support ventilation (PSV) is often associated with patient-ventilator asynchrony. Proportional assist ventilation (PAV) offers inspiratory assistance proportional to patient effort, minimizing patient-ventilator asynchrony. The objective of this study was to evaluate the influence of respiratory mechanics and patient effort on patient-ventilator asynchrony during PSV and PAV plus (PAV+).

METHODS

We used a mechanical lung simulator and studied 3 respiratory mechanics profiles (normal, obstructive, and restrictive), with variations in the duration of inspiratory effort: 0.5, 1.0, 1.5, and 2.0 s. The Auto-Trak system was studied in ventilators when available. Outcome measures included inspiratory trigger delay, expiratory trigger asynchrony, and tidal volume (V_T).

RESULTS

Inspiratory trigger delay was greater in the obstructive respiratory mechanics profile and greatest with a effort of 2.0 s (160 ms); cycling asynchrony, particularly delayed cycling, was common in the obstructive profile, whereas the restrictive profile was associated with premature cycling. In comparison with PSV, PAV+ improved patient-ventilator synchrony, with a shorter triggering delay (28 ms vs 116 ms) and no cycling asynchrony in the restrictive profile. V_T was lower with PAV+ than with PSV (630 mL vs 837 mL), as it was with the single-limb circuit ventilator (570 mL vs 837 mL). PAV+ mode was associated with longer cycling delays than were the other ventilation modes, especially for the obstructive profile and higher effort values. Auto-Trak eliminated automatic triggering.

CONCLUSIONS

Mechanical ventilation asynchrony was influenced by effort, respiratory mechanics, ventilator type, and ventilation mode. In PSV mode, delayed cycling was associated with shorter effort in obstructive respiratory mechanics profiles, whereas premature cycling was more common with longer effort and a restrictive profile. PAV+ prevented premature cycling but not delayed cycling, especially in obstructive respiratory mechanics profiles, and it was associated with a lower V_T.

Effectiveness of hands-on tutoring and guided self-directed learning versus self-directed learning alone to educate critical care fellows on mechanical ventilation - a pilot project

BACKGROUND

Physicians require extensive training to achieve proficiency in mechanical ventilator (MV) management of the critically ill patients. Guided self-directed learning (GSDL) is usually the method used to learn. However, it is unclear if this is the most proficient approach to teaching mechanical ventilation to critical care fellows. We, therefore, investigated whether critical care fellows achieve higher scores on standardized testing and report higher satisfaction after participating in a hands-on tutorial combined with GSDL compared to self-directed learning alone.

METHODS

First-year Pulmonary and Critical Care Medicine (PCCM) fellows (n=6) and Critical Care Internal Medicine (CCIM) (n=8) fellows participated. Satisfaction was assessed using the Likert scale. MV knowledge assessment was performed by administering a standardized 25-question multiple choice pre- and posttest. For 2 weeks the CCIM fellows were exposed to GSDL, while the PCCM fellows received hands-on tutoring combined with GSDL.

RESULTS

Ninety-three percentage (6 PCCM and 7 CCIM fellows, total of 13 fellows) completed all evaluations and were included in the final analysis. CCIM and PCCM fellows scored similarly in the pretest (64% vs. 52%, p=0.13). Following interventions, the posttest scores increased in both groups. However, no significant difference was observed based on the interventions (74% vs. 77%, p=0.39). The absolute improvement with the hands-on-tutoring and GSDL group was higher than GSDL alone (25% vs. 10%, p=0.07). Improved satisfaction scores were noted with hands-on tutoring.

CONCLUSIONS

Hands-on tutoring combined with GSDL and GSDL alone were both associated with an improvement in posttest scores. Absolute improvement in test and satisfaction scores both trended higher in the hands-on tutorial group combined with GSDL group.

An Official American Thoracic Society Clinical Practice Guideline: Pediatric Chronic Home Invasive Ventilation

BACKGROUND

Children with chronic invasive ventilator dependence living at home are a diverse group of children with special health care needs. Medical oversight, equipment management, and community resources vary widely. There are no clinical practice guidelines available to health care professionals for the safe hospital discharge and home management of these complex children.

PURPOSE

To develop evidence-based clinical practice guidelines for the hospital discharge and home/community management of children requiring chronic invasive ventilation.

METHODS

The Pediatric Assembly of the American Thoracic Society assembled an interdisciplinary workgroup with expertise in the care of children requiring chronic invasive ventilation. The experts developed four questions of clinical importance and used an evidence-based strategy to identify relevant medical evidence. Grading of Recommendations Assessment, Development, and Evaluation (GRADE) methodology was used to formulate and grade recommendations.

RESULTS

Clinical practice recommendations for the management of children with chronic ventilator dependence at home are provided, and the evidence supporting each recommendation is discussed.

CONCLUSIONS

Collaborative generalist and subspecialist comanagement is the Medical Home model most likely to be successful for the care of children requiring chronic invasive ventilation. Standardized hospital discharge criteria are suggested. An awake, trained caregiver should be present at all times, and at least two family caregivers should be trained specifically for the child's care. Standardized equipment for monitoring, emergency preparedness, and airway clearance are outlined. The recommendations presented are based on the current evidence and expert opinion and will require an update as new evidence and/or technologies become available.

Efficacy of a Low-Tidal Volume Ventilation Strategy to Prevent Reperfusion Lung Injury after Pulmonary Thromboendarterectomy

RATIONALE

Reperfusion lung injury is a postoperative complication of pulmonary thromboendarterectomy that can significantly affect morbidity and mortality. Studies in other postoperative patient populations have demonstrated a reduction in acute lung injury with the use of a low-tidal volume (Vt) ventilation strategy. Whether this approach benefits patients undergoing thromboendarterectomy is unknown.

OBJECTIVES

We sought to determine if low-Vt ventilation reduces reperfusion lung injury in patients with chronic thromboembolic pulmonary hypertension undergoing thromboendarterectomy.

METHODS

Patients undergoing thromboendarterectomy at one center were randomized to receive either low (6 ml/kg predicted body weight) or usual care Vts (10 ml/kg) from the initiation of mechanical ventilation in the operating room through Postoperative Day 3. The primary endpoint was the onset of reperfusion lung injury. Secondary outcomes included severity of hypoxemia, days on mechanical ventilation, and intensive care unit and hospital lengths of stay.

MEASUREMENTS AND MAIN RESULTS

A total of 128 patients were enrolled and included in the analysis; 63 were randomized to the low-Vt group and 65 were randomized to the usual care group. There was no statistically significant difference in the incidence of reperfusion lung injury between groups (32%, n=20 in the low-Vt group vs. 23%, n=15 in the usual care group; P=0.367). Although differences were noted in plateau pressures (17.9 cm H2O vs. 20.1 cm H2O, P<0.001) and peak inspiratory pressures (20.4 cm H2O vs. 23.0 cm H2O, P<0.001) between the low-Vt and usual care groups, respectively, mean airway pressures, PaO2/FiO2, days on mechanical ventilation, and ICU and hospital lengths of stay were all similar between groups.

CONCLUSIONS

In patients with chronic thromboembolic pulmonary hypertension undergoing pulmonary thromboendarterectomy, intra- and postoperative ventilation using low Vts (6 mg/kg) compared with usual care Vts (10 mg/kg) does not reduce the incidence of reperfusion lung injury or improve clinical outcomes. Clinical trial registered with www.clinicaltrials.gov (NCT00747045).

Postperfusion lung syndrome and related sequelae

Postperfusion lung syndrome is a rare but sometimes lethal complication secondary to cardiopulmonary bypass. It often leads to multiorgan failure and mixed acid-base disturbances, thus making a refractory condition. A 69-year-old female, undergoing a successful cardiac lipoma resection under cardiopulmonary bypass, unfortunately developed postperfusion lung syndrome with associated multiorgan failure and triple acid-base disturbances (TABDs). Her condition deteriorated rapidly on postoperative day three and became moribund. This article reports a rare association following a surgical resection of cardiac lipoma, complicated with postperfusion lung syndrome and high-anion-gap and hyperchloride TABDs. It is recommended that proper positive end-expiratory pressure (PEEP) (5-10 cmH2O) with low tidal volume (6 mL/kg) be applied in order to minimize the compromise to cardiac function of cardiac surgical patients.