Use Of Low Tidal Volume Ventilation Research Articles

Decreased Utilization of Low Tidal Volume Ventilation Outside of the Intensive Care Unit as Compared to Inside.

Background: Investigations into the use of low tidal volume ventilation (LTVV) have been performed for patients in emergency departments (EDs) or intensive care units (ICUs). Practice differences between the ICU and non-ICU care areas have not been described. We hypothesized that the initial implementation of LTVV would be better inside ICUs than outside. Methods: This is a retrospective observational study of patients initiated on invasive mechanical ventilation (IMV) between January 1, 2016, and July 17, 2019. Initial recorded tidal volumes after intubation were used to compare the use of LTVV between care areas. Low tidal volume was considered 6.5 cc/kg of ideal body weight (IBW) or less. The primary outcome was the initiation of low tidal volume. Sensitivity analyses used a tidal volume of 8 cc/kg of IBW or less, and direct comparisons were performed between the ICU, ED, and wards. Results: There were 6392 initiations of IMV: 2217 (34.7%) in the ICU and 4175 (65.3%) outside. LTVV was more likely to be initiated in the ICU than outside (46.5% vs 34.2%; adjusted odds ratio [aOR] 0.62, 95% confidence interval [CI] 0.56-0.71, P < .01). The ICU also had more implementation when PaO2/FiO2 ratio was less than 300, (48.0% vs 34.6%; aOR 0.59, 95% CI 0.48-0.71, P < .01). When comparing individual locations, wards had lower odds of LTVV than the ICU (aOR 0.82, 95% CI 0.70-0.96, P = .02), the ED had lower odds than the ICU (aOR 0.55, 95% CI 0.48-0.63, P < .01), and the ED had lower odds than the wards (aOR 0.66, 95% CI 0.56-0.77, P < .01). Interpretation: Initial low tidal volumes were more likely to be initiated in the ICU than outside. This finding remained when examining only patients with a PaO2/FiO2 ratio less than 300. Care areas outside of the ICU do not employ LTVV as often as ICUs and are, therefore, a possible target for process improvement.

Hospital Variation in Mortality and Ventilator Management among Mechanically Ventilated Patients with ARDS.

Acute Respiratory Distress Syndrome (ARDS) is associated with significant mortality. Despite the mortality benefits of lung protective ventilation, adherence rates to evidence-based ventilator practice have remained low and ARDS mortality has remained high. Determine variation in ARDS mortality and adherence to low tidal volume ventilation (LTV) across US hospitals. We identified mechanically ventilated patients with ARDS using data from Philips eICU (2014-2015). We then used multi-variable hierarchical logistic regression models with hospital site as the random effect and patient and hospital level factors as fixed effects to assess the hospital risk adjusted mortality rate and median odds ratio for the association between mortality and hospital site. We then assessed associations between adherence to LTV (defined as 4-8 mL/kg PBW) and hospital risk adjusted mortality rates using Spearman correlation. Among 4441 patients admitted at 110 hospitals with ARDS, the hospital risk-adjusted mortality rate ranged from 19% to 39%, and the MOR for hospital of admission was 1.33 (95% CI 1.25-1.41). Among 3070 patients at 72 hospitals with available ventilator data, 73% of patients had a median set Vt between 4 to 8 mL/kg PBW; hospital adherence rates to LTV ranged from 13% to 95%. There was no association between hospital adherence to LTV and risk-adjusted mortality rate (spearman correlation coefficient -0.01, p = .93). Similarly, among 956 patients who started with a Vt > 8 mL/kg PBW, there was no association between the percent of patients at each hospital whose Vt was decreased to ≤ 8 mL/kg PBW and risk adjusted mortality rate (spearman correlation coefficient .05, p = .73). Risk adjusted mortality and use of LTV for patients with ARDS varied widely across hospitals. However, hospital adherence to LTV was not associated with ARDS mortality rates. Further evaluation of hospital practices associated with lower ARDS mortality are warranted.

Low Tidal Volume Ventilation for Emergency Department Patients: A Systematic Review and Meta-Analysis on Practice Patterns and Clinical Impact.

Data suggest that low tidal volume ventilation (LTVV) initiated in the emergency department (ED) has a positive impact on outcome. This systematic review and meta-analysis quantify the impact of ED-based LTVV on outcomes and ventilator settings in the ED and ICU. We systematically reviewed MEDLINE, EMBASE, Scopus, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, references, conferences, and ClinicalTrials.gov. Randomized and nonrandomized studies of mechanically ventilated ED adults were eligible. Two reviewers independently screened abstracts. The primary outcome was mortality. Secondary outcomes included ventilation duration, lengths of stay, and occurrence rate of acute respiratory distress syndrome (ARDS). We assessed impact of ED LTVV interventions on ED and ICU tidal volumes. The search identified 1,023 studies. Eleven studies (n = 12,912) provided outcome data and were meta-analyzed; 10 additional studies (n = 1,863) provided descriptive ED tidal volume data. Overall quality of evidence was low. Random effect meta-analytic models revealed that ED LTVV was associated with lower mortality (26.5%) versus non-LTVV (31.1%) (odds ratio, 0.80 [0.72-0.88]). ED LTVV was associated with shorter ICU (mean difference, -1.0; 95% CI, -1.7 to -0.3) and hospital (mean difference, -1.2; 95% CI, -2.3 to -0.1) lengths of stay, more ventilator-free days (mean difference, 1.4; 95% CI, 0.4-2.4), and lower occurrence rate (4.5% vs 8.3%) of ARDS (odds ratio, 0.57 [0.44-0.75]). ED LTVV interventions were associated with reductions in ED (-1.5-mL/kg predicted body weight [PBW] [-1.9 to -1.0]; p < 0.001) and ICU (-1.0-mL/kg PBW [-1.8 to -0.2]; p = 0.01) tidal volume. The use of LTVV in the ED is associated with improved clinical outcomes and increased use of lung protection, recognizing low quality of evidence in this domain. Interventions aimed at implementing and sustaining LTVV in the ED should be explored.

Sex Differences in Use of Low Tidal Volume Ventilation in COVID-19-Insights From the PRoVENT-COVID Study.

The purpose of this study was to compare and understand differences in the use of low tidal volume ventilation (LTVV) between females and males with acute respiratory distress syndrome (ARDS) related to coronavirus disease 2019 (COVID-19). This is a post-hoc analysis of an observational study in invasively ventilated patients with ARDS related to COVID-19 in 22 ICUs in the Netherlands. The primary endpoint was the use of LTVV, defined as having received a median tidal volume (VT) ≤6 ml/kg predicted body weight (PBW) during controlled ventilation. A mediation analysis was used to investigate the impact of anthropometric factors, next to the impact of sex per se. The analysis included 934 patients, 251 females and 683 males. All the patients had ARDS, and there were no differences in ARDS severity between the sexes. On the first day of ventilation, females received ventilation with a higher median VT compared with males [6.8 (interquartile range (IQR) 6.0–7.6 vs. 6.3 (IQR 5.8–6.9) ml/kg PBW; p < 0.001]. Consequently, females received LTVV less often than males (23 vs. 34%; p = 0.003). The difference in the use of LTVV became smaller but persisted over the next days (27 vs. 36%; p = 0.046 at day 2 and 28 vs. 38%; p = 0.030 at day 3). The difference in the use LTVV was significantly mediated by sex per se [average direct effect of the female sex, 7.5% (95% CI, 1.7–13.3%); p = 0.011] and by differences in the body height [average causal mediation effect, −17.5% (−21.5 to −13.5%); p < 0.001], but not by the differences in actual body weight [average causal mediation effect, 0.2% (−0.8 to 1.2%); p = 0.715]. In conclusion, in this cohort of patients with ARDS related to COVID-19, females received LTVV less often than males in the first days of invasive ventilation. The difference in the use of LTVV was mainly driven by an anthropometric factor, namely, body height. Use of LTVV may improve by paying attention to correct titration of VT, which should be based on PBW, which is a function of body height.

Geoeconomic variations in epidemiology, ventilation management, and outcomes in invasively ventilated intensive care unit patients without acute respiratory distress syndrome: a pooled analysis of four observational studies

SummaryBackgroundGeoeconomic variations in epidemiology, the practice of ventilation, and outcome in invasively ventilated intensive care unit (ICU) patients without acute respiratory distress syndrome (ARDS) remain unexplored. In this analysis we aim to address these gaps using individual patient data of four large observational studies.MethodsIn this pooled analysis we harmonised individual patient data from the ERICC, LUNG SAFE, PRoVENT, and PRoVENT-iMiC prospective observational studies, which were conducted from June, 2011, to December, 2018, in 534 ICUs in 54 countries. We used the 2016 World Bank classification to define two geoeconomic regions: middle-income countries (MICs) and high-income countries (HICs). ARDS was defined according to the Berlin criteria. Descriptive statistics were used to compare patients in MICs versus HICs. The primary outcome was the use of low tidal volume ventilation (LTVV) for the first 3 days of mechanical ventilation. Secondary outcomes were key ventilation parameters (tidal volume size, positive end-expiratory pressure, fraction of inspired oxygen, peak pressure, plateau pressure, driving pressure, and respiratory rate), patient characteristics, the risk for and actual development of acute respiratory distress syndrome after the first day of ventilation, duration of ventilation, ICU length of stay, and ICU mortality.FindingsOf the 7608 patients included in the original studies, this analysis included 3852 patients without ARDS, of whom 2345 were from MICs and 1507 were from HICs. Patients in MICs were younger, shorter and with a slightly lower body-mass index, more often had diabetes and active cancer, but less often chronic obstructive pulmonary disease and heart failure than patients from HICs. Sequential organ failure assessment scores were similar in MICs and HICs. Use of LTVV in MICs and HICs was comparable (42·4% vs 44·2%; absolute difference –1·69 [–9·58 to 6·11] p=0·67; data available in 3174 [82%] of 3852 patients). The median applied positive end expiratory pressure was lower in MICs than in HICs (5 [IQR 5–8] vs 6 [5–8] cm H2O; p=0·0011). ICU mortality was higher in MICs than in HICs (30·5% vs 19·9%; p=0·0004; adjusted effect 16·41% [95% CI 9·52–23·52]; p<0·0001) and was inversely associated with gross domestic product (adjusted odds ratio for a US$10 000 increase per capita 0·80 [95% CI 0·75–0·86]; p<0·0001).InterpretationDespite similar disease severity and ventilation management, ICU mortality in patients without ARDS is higher in MICs than in HICs, with a strong association with country-level economic status.FundingNo funding.

Sex difference and intra-operative tidal volume: Insights from the LAS VEGAS study.

One key element of lung-protective ventilation is the use of a low tidal volume (VT). A sex difference in use of low tidal volume ventilation (LTVV) has been described in critically ill ICU patients. The aim of this study was to determine whether a sex difference in use of LTVV also exists in operating room patients, and if present what factors drive this difference. This is a posthoc analysis of LAS VEGAS, a 1-week worldwide observational study in adults requiring intra-operative ventilation during general anaesthesia for surgery in 146 hospitals in 29 countries. Women and men were compared with respect to use of LTVV, defined as VT of 8 ml kg-1 or less predicted bodyweight (PBW). A VT was deemed 'default' if the set VT was a round number. A mediation analysis assessed which factors may explain the sex difference in use of LTVV during intra-operative ventilation. This analysis includes 9864 patients, of whom 5425 (55%) were women. A default VT was often set, both in women and men; mode VT was 500 ml. Median [IQR] VT was higher in women than in men (8.6 [7.7 to 9.6] vs. 7.6 [6.8 to 8.4] ml kg-1 PBW, P < 0.001). Compared with men, women were twice as likely not to receive LTVV [68.8 vs. 36.0%; relative risk ratio 2.1 (95% CI 1.9 to 2.1), P < 0.001]. In the mediation analysis, patients' height and actual body weight (ABW) explained 81 and 18% of the sex difference in use of LTVV, respectively; it was not explained by the use of a default VT. In this worldwide cohort of patients receiving intra-operative ventilation during general anaesthesia for surgery, women received a higher VT than men during intra-operative ventilation. The risk for a female not to receive LTVV during surgery was double that of males. Height and ABW were the two mediators of the sex difference in use of LTVV. The study was registered at Clinicaltrials.gov, NCT01601223.

Clinician Recognition of the Acute Respiratory Distress Syndrome: Risk Factors for Under-Recognition and Trends Over Time.

The acute respiratory distress syndrome is common in critically ill patients. Recognition is crucial because acute respiratory distress syndrome is associated with a high mortality rate, and low tidal volume ventilation improves mortality. However, acute respiratory distress syndrome often goes unrecognized. Risk factors for under-recognition and trends over time have not been fully described. Retrospective chart review of patients with acute respiratory distress syndrome from a prospective cohort study of critically ill patients. For each patient's ICU stay, we searched the chart for terms that indicated that acute respiratory distress syndrome was diagnosed, in the differential diagnosis, or treated with low tidal volume ventilation. ICUs at a tertiary hospital at the University of California, San Francisco between 2008 and 2016. Critically ill patients with acute respiratory distress syndrome. None. Acute respiratory distress syndrome was recognized in 70% of patients, and recognition increased from 60% in 2008-2009 to 92% in 2016 (p = 0.004). Use of tidal volumes less than 6.5 mL/kg also increased (p < 0.001) from 20% to 92%. Increased acute respiratory distress syndrome severity (p = 0.01) and vasopressor use (p = 0.04) were associated with greater recognition. Clinician diagnosis of acute respiratory distress syndrome and inclusion of acute respiratory distress syndrome in the differential diagnosis were associated with tidal volumes less than 6.5 mL/kg (51% use of tidal volume ≤ 6.5 mL/kg if acute respiratory distress syndrome recognized vs 15% if not recognized; p = 0.002). Diagnosing acute respiratory distress syndrome was associated with lower tidal volume in multivariate analysis. Although acute respiratory distress syndrome recognition and low tidal volume ventilation use have increased over time, they remain less than universal. Clinician recognition of acute respiratory distress syndrome is associated with both systemic and respiratory severity of illness and is also associated with use of low tidal volume ventilation.

A quantitative approach for the analysis of clinician recognition of acute respiratory distress syndrome using electronic health record data.

Despite its efficacy, low tidal volume ventilation (LTVV) remains severely underutilized for patients with acute respiratory distress syndrome (ARDS). Physician under-recognition of ARDS is a significant barrier to LTVV use. We propose a computational method that addresses some of the limitations of the current approaches to automated measurement of whether ARDS is recognized by physicians. To quantify patient and physician factors affecting physicians' tidal volume selection and to build a computational model of physician recognition of ARDS that accounts for these factors. In this cross-sectional study, electronic health record data were collected for 361 ARDS patients and 388 non-ARDS hypoxemic (control) patients in nine adult intensive care units at four hospitals between June 24 and December 31, 2013. Standardized tidal volumes (mL/kg predicted body weight) were chosen as a proxy for physician decision-making behavior. Using data-science approaches, we quantified the effect of eight factors (six severity of illness, two physician behaviors) on selected standardized tidal volumes in ARDS and control patients. Significant factors were incorporated in computational behavioral models of physician recognition of ARDS. Hypoxemia severity and ARDS documentation in physicians' notes were associated with lower standardized tidal volumes in the ARDS cohort. Greater patient height was associated with lower standardized tidal volumes (which is already normalized for height) in both ARDS and control patients. The recognition model yielded a mean (99% confidence interval) physician recognition of ARDS of 22% (9%-42%) for mild, 34% (19%-49%) for moderate, and 67% (41%-100%) for severe ARDS. In this study, patient characteristics and physician behaviors were demonstrated to be associated with differences in ventilator management in both ARDS and control patients. Our model of physician ARDS recognition measurement accounts for these clinical variables, providing an electronic approach that moves beyond relying on chart documentation or resource intensive approaches.

788: Can we achieve low tidal volume ventilation in pregnant women with acute respiratory distress syndrome?

Lung protective low-tidal volume ventilation (LTVV) has been shown to decrease mortality in Acute Respiratory Distress Syndrome (ARDS). ARDS occurs more frequently in pregnancy, yet changes in respiratory physiology during pregnancy and concern for fetal-acid base status may interfere with LTVV strategy. This study assessed use of LTVV in pregnancy and identified maternal and fetal outcomes of mechanically ventilated pregnant patients with ARDS. This is a retrospective cohort study of women with ARDS who were mechanically ventilated for greater than 24 hours between January 2012 and February 2017 at a tertiary care center. ARDS was defined clinically, and LTVV was defined as weighted daily average tidal volume ≤8 mL/kg of ideal body weight. Pregnant patients (N=23) had 128 days of ventilation, and non-pregnant patients (N=681) had 3,174 days. Demographic, pregnancy and fetal outcome data were collected on pregnant patients. Compliance with LTVV was stratified by trimester, and groups compared with chi-squared analysis. We had no maternal deaths and extracorporeal membrane oxygenation (ECMO) was used in 8.7% of patients (N=2). Causes of ARDS included sepsis, pneumonia, and asthma exacerbation. Obstetric complications occurred frequently, with 21.7% (N=5) experiencing preeclampsia, and 50.0% (N=11) delivering preterm. Mean infant birth weight was 2348g ± 14.6. There were 3 perinatal demises (2 intrauterine, 1 neonatal). In pregnant and non-pregnant patients respectively, weighted average daily tidal volume was 7.8 ml/kg ±1.2 and 7.27 ml/kg ±1.55, and overall LTVV use was 87.0% and 81.9%. LTVV was utilized in 93.3% of patients in the first, 85.1% in the second, and 71.0% in the third trimester. Use of LTVV in the third trimester was significantly less than the first and second (p=0.05). Pregnant patients with ARDS encountered significant adverse maternal and fetal outcomes, with half delivering preterm and over 20% developing preeclampsia. LTVV use was comparable between pregnant and non-pregnant patients, but was utilized more frequently in the first and second trimesters compared to the third. Given the significant morbidity seen with ARDS in pregnancy, additional multi-center studies are needed to evaluate factors associated with increased utilization of LTVV, and the effect of LTVV on maternal and fetal outcomes.

Low tidal volume ventilation use remains low in patients with acute respiratory distress syndrome at a single center

PurposeLow tidal volume ventilation (LTVV) reduces mortality in acute respiratory distress syndrome (ARDS) patients. Understanding local barriers to LTVV use at a former ARDS Network hospital may provide new insight to improve LTVV implementation. MethodsA cohort of 214 randomly selected adults met the Berlin definition of ARDS at Harborview Medical Center between 2008 and 2012. The primary outcome was the receipt of LTVV (tidal volume of ≤6.5mL/kg predicted body weight) within 48h of ARDS onset. We constructed a multivariable logistic regression model to identify factors associated with the outcome. ResultsOnly 27% of patients received tidal volumes of ≤6.5mL/kg PBW within 48h of ARDS onset. Increasing plateau pressure (OR 1.11; 95% CI 1.03 to 1.19; p-value<0.01) was positively associated with LTVV use while increasing PaO2:FIO2 ratio was negatively associated (OR 0.75; 95% CI 0.57 to 0.98; p-value 0.03). Physicians documented an ARDS diagnosis in only 21% of the cohort. Neither patient height nor gender was associated with LTVV use. ConclusionsMost ARDS patients did not receive LTVV despite implementation of a protocol. ARDS was also recognized in a minority of patients, suggesting an opportunity for improvement of care.

Poor Adherence to Lung-Protective Mechanical Ventilation in Pediatric Acute Respiratory Distress Syndrome.

To determine the frequency of low-tidal volume ventilation in pediatric acute respiratory distress syndrome and assess if any demographic or clinical factors improve low-tidal volume ventilation adherence. Descriptive post hoc analysis of four multicenter pediatric acute respiratory distress syndrome studies. Twenty-six academic PICU. Three hundred fifteen pediatric acute respiratory distress syndrome patients. All patients who received conventional mechanical ventilation at hours 0 and 24 of pediatric acute respiratory distress syndrome who had data to calculate ideal body weight were included. Two cutoff points for low-tidal volume ventilation were assessed: less than or equal to 6.5 mL/kg of ideal body weight and less than or equal to 8 mL/kg of ideal body weight. Of 555 patients, we excluded 240 for other respiratory support modes or missing data. The remaining 315 patients had a median PaO2-to-FIO2 ratio of 140 (interquartile range, 90-201), and there were no differences in demographics between those who did and did not receive low-tidal volume ventilation. With tidal volume cutoff of less than or equal to 6.5 mL/kg of ideal body weight, the adherence rate was 32% at hour 0 and 33% at hour 24. A low-tidal volume ventilation cutoff of tidal volume less than or equal to 8 mL/kg of ideal body weight resulted in an adherence rate of 58% at hour 0 and 60% at hour 24. Low-tidal volume ventilation use was no different by severity of pediatric acute respiratory distress syndrome nor did adherence improve over time. At hour 0, overweight children were less likely to receive low-tidal volume ventilation less than or equal to 6.5 mL/kg ideal body weight (11% overweight vs 38% nonoverweight; p = 0.02); no difference was noted by hour 24. Furthermore, in the overweight group, using admission weight instead of ideal body weight resulted in misclassification of up to 14% of patients as receiving low-tidal volume ventilation when they actually were not. Low-tidal volume ventilation is underused in the first 24 hours of pediatric acute respiratory distress syndrome. Age, Pediatric Risk of Mortality-III, and pediatric acute respiratory distress syndrome severity were not associated with improved low-tidal volume ventilation adherence nor did adherence improve over time. Overweight children were less likely to receive low-tidal volume ventilation strategies in the first day of illness.

Low Tidal Volume Ventilation Use in Acute Respiratory Distress Syndrome.

Low tidal volume ventilation lowers mortality in the acute respiratory distress syndrome. Previous studies reported poor low tidal volume ventilation implementation. We sought to determine the rate, quality, and predictors of low tidal volume ventilation use. Retrospective cross-sectional study. One academic and three community hospitals in the Chicago region. A total of 362 adults meeting the Berlin Definition of acute respiratory distress syndrome consecutively admitted between June and December 2013. Seventy patients (19.3%) were treated with low tidal volume ventilation (tidal volume < 6.5 mL/kg predicted body weight) at some time during mechanical ventilation. In total, 22.2% of patients requiring an FIO2 greater than 40% and 37.3% of patients with FIO2 greater than 40% and plateau pressure greater than 30 cm H2O received low tidal volume ventilation. The entire cohort received low tidal volume ventilation 11.4% of the time patients had acute respiratory distress syndrome. Among patients who received low tidal volume ventilation, the mean (SD) percentage of acute respiratory distress syndrome time it was used was 59.1% (38.2%), and 34% waited more than 72 hours prior to low tidal volume ventilation initiation. Women were less likely to receive low tidal volume ventilation, whereas sepsis and FIO2 greater than 40% were associated with increased odds of low tidal volume ventilation use. Four attending physicians (6.2%) initiated low tidal volume ventilation within 1 day of acute respiratory distress syndrome onset for greater than or equal to 50% of their patients, whereas 34 physicians (52.3%) never initiated low tidal volume ventilation within 1 day of acute respiratory distress syndrome onset. In total, 54.4% of patients received a tidal volume less than 8 mL/kg predicted body weight, and the mean tidal volume during the first 72 hours after acute respiratory distress syndrome onset was never less than 8 mL/kg predicted body weight. More than 12 years after publication of the landmark low tidal volume ventilation study, use remains poor. Interventions that improve adoption of low tidal volume ventilation are needed.