Mean Airway Pressure As a Predictor of 90-Day Mortality in Mechanically Ventilated Patients.

OBJECTIVES: To determine the association between mean airway pressure and 90-day mortality in patients with acute respiratory failure requiring mechanical ventilation and to compare the predictive ability of mean airway pressure compared with inspiratory plateau pressure and driving pressure. DESIGN: Prospective observational cohort. SETTING: Five ICUs in Lima, Peru. SUBJECTS: Adults requiring invasive mechanical ventilation via endotracheal tube for acute respiratory failure. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Of potentially eligible participants (n = 1,500), 65 (4%) were missing baseline mean airway pressure, while 352 (23.5%) were missing baseline plateau pressure and driving pressure. Ultimately, 1,429 participants were included in the analysis with an average age of 59 ± 19 years, 45% female, and a mean PaO2/FIO2 ratio of 248 ± 147 mm Hg at baseline. Overall, 90-day mortality was 50.4%. Median baseline mean airway pressure was 13 cm H2O (interquartile range, 10-16 cm H2O) in participants who died compared to a median mean airway pressure of 12 cm H2O (interquartile range, 10-14 cm H2O) in participants who survived greater than 90 days (p < 0.001). Mean airway pressure was independently associated with 90-day mortality (odds ratio, 1.38 for difference comparing the 75th to the 25th percentile for mean airway pressure; 95% CI, 1.10-1.74) after adjusting for age, sex, baseline Acute Physiology and Chronic Health Evaluation III, baseline PaO2/FIO2 (modeled with restricted cubic spline), baseline positive end-expiratory pressure, baseline tidal volume, and hospital site. In predicting 90-day mortality, baseline mean airway pressure demonstrated similar discriminative ability (adjusted area under the curve = 0.69) and calibration characteristics as baseline plateau pressure and driving pressure. CONCLUSIONS: In a multicenter prospective cohort, baseline mean airway pressure was independently associated with 90-day mortality in mechanically ventilated participants and predicts mortality similarly to plateau pressure and driving pressure. Because mean airway pressure is readily available on all mechanically ventilated patients and all ventilator modes, it is a potentially more useful predictor of mortality in acute respiratory failure.

Premature, Opportune, and Delayed Weaning in Mechanically Ventilated Patients: A Call for Implementation of Weaning Protocols in Low- and Middle-Income Countries.

OBJECTIVES: Weaning protocols establish readiness-to-wean criteria to determine the opportune moment to conduct a spontaneous breathing trial. Weaning protocols have not been widely adopted or evaluated in ICUs in low- and middle-income countries. We sought to compare clinical outcomes between participants whose weaning trials were retrospectively determined to have been premature, opportune, or delayed based on when they met readiness-to-wean criteria. DESIGN: Prospective, multicenter observational study. SETTING: Five medical ICUs in four public hospitals in Lima, Perú. SUBJECTS: Adults with acute respiratory failure and at least 24 hours of invasive mechanical ventilation (n = 1,657). INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We established six readiness-to-wean criteria and retrospectively categorized our sample into three weaning groups: 1) premature: if the weaning trial took place before fulfilling all criteria, 2) opportune: if the weaning trial took place within 24 hours after fulfilling the criteria, and 3) delayed: if the weaning trial took place over 24 hours after fulfilling criteria. We compared 90-day mortality, ventilator-free days, ICU-free days, and hospital-free days between premature, opportune, and delayed weaning groups. In our sample, 761 participants (60.8%) were classified as having a premature weaning trial, 196 underwent opportune weaning (15.7%), and 295 experienced delayed weaning (23.6%). There was no significant difference in 90-day mortality between the groups. Both the premature and delayed weaning groups had poorer clinical outcomes with fewer ventilator-free days (-2.18, p = 0.008) and (-3.49, p < 0.001), ICU-free days (-2.25, p = 0.001) and (-3.72, p < 0.001), and hospital-free days (-2.76, p = 0.044) and (-4.53, p = 0.004), respectively, compared with the opportune weaning group. CONCLUSIONS: Better clinical outcomes occur with opportune weaning compared with premature and delayed weaning. If readiness-to-wean criteria can be applied in resource-limited settings, it may improve ICU outcomes associated with opportune weaning.

Low cigarette smoking prevalence in peri-urban Peru: results from a population-based study of tobacco use by self-report and urine cotinine.

BACKGROUND: A recent study found lower self-reported prevalence of tobacco smoking in a peri-urban area of Lima, Peru than previously reported in urban samples. These regions encompass substantial proportions of Peru's population - ones at greater risk of disease due to reduced healthcare access - but have been less often studied. We validate low smoking prevalence with urine cotinine and characterize chronic disease and lung function outcomes between non-, occasional, and daily smokers. METHODS: Data are from the CRONICAS Cohort Study, a population-based longitudinal study in four low-resource Peruvian settings, which began in 2010. Of a baseline cohort of 2978 adults, we prospectively followed 2583 (87%) to determine prevalence of chronic illness. RESULTS: In a baseline sub-sample of 382 participants, median adjusted cotinine was 0.0 mcg/mg (IQR 0-0) for both self-reported non-smokers and occasional smokers compared to 172.3 mcg/mg (IQR 0-709.2) for daily smokers. Creatinine-adjusted cotinine validated daily smoking prevalence of 4.7% at a cutoff of 100 mcg/mg. Kappa statistic for daily smoking and creatinine- adjusted cotinine ≥100 mcg/mg was 0.65 (95% CI 0.47, 0.83), indicating substantial agreement. At baseline, we found 3.3% daily and 8.9% occasional smoking by self-report for the full cohort. Follow-up indicated little difference in chronic disease prevalence between groups. Daily smokers trended toward having a greater decline in FVC (-1%; 95% CI -2.9, 0.8) and FEV1 (-1.3%; 95% CI -3.2, 0.6) over 40 months when compared to non-smokers, whereas the decline in lung function for occasional smokers was similar compared to non-smokers (-0.2% FVC; 95% CI -1.5, 1.0) and (0% FEV1; 95% CI -1.3, 1.3). CONCLUSIONS: Our data places Peru within a previously-described pattern of smoking found in much of Latin America, favoring occasional over daily smoking and low cigarette consumption. We determine that there are not significant differences between smoking groups concerning chronic disease outcomes. We favor distinguishing between daily and occasional smokers in order to accurately characterize these low-use populations.