Automatic detection of reverse-triggering related asynchronies during mechanical ventilation in ARDS patients using flow and pressure signals.

Asynchrony due to reverse-triggering (RT) may appear in ARDS patients. The objective of this study is to validate an algorithm developed to detect these alterations in patient-ventilator interaction. We developed an algorithm that uses flow and airway pressure signals to classify breaths as normal, RT with or without breath stacking (BS) and patient initiated double-triggering (DT). The diagnostic performance of the algorithm was validated using two datasets of breaths, that are classified as stated above. The first dataset classification was based on visual inspection of esophageal pressure (Pes) signal from 699 breaths recorded from 11 ARDS patients. The other classification was obtained by vote of a group of 7 experts (2 physicians and 5 respiratory therapists, who were trained in ICU), who evaluated 1881 breaths gathered from recordings from 99 subjects. Experts used airway pressure and flow signals for breaths classification. The RT with or without BS represented 19% and 37% of breaths in Pes dataset while their frequency in the expert's dataset were 3% and 12%, respectively. The DT was very infrequent in both datasets. Algorithm classification accuracy was 0.92 (95% CI 0.89-0.94, P < 0.001) and 0.96 (95% CI 0.95-0.97, P < 0.001), in comparison with Pes and experts' opinion. Kappa statistics were 0.86 and 0.84, respectively. The algorithm precision, sensitivity and specificity for individual asynchronies were excellent. The algorithm yields an excellent accuracy for detecting clinically relevant asynchronies related to RT.

Epidemiology, patterns of care and prognosis of acute kidney injury in critically ill patients: A multicenter study in Argentina (The EPIRA study).

BACKGROUND: Acute kidney injury (AKI) is associated with high morbidity and mortality rates in the intensive care unit (ICU). In low- and middle-income countries (LMICs), epidemiological information about this condition is still scarce. Our main objective was to characterize its epidemiology, prognosis, and its treatment. METHODS: This multicenter prospective cohort study included 1466 patients from 35 ICUs during 6 months in Argentina in 2018. Risk factors and outcomes in patients with and without AKI, and between AKI on admission (AKIadm) and that developed during hospitalization (AKIhosp) were analyzed. RESULTS: AKI occurred in 61.3% of patients (900/1466); 72.6% were AKIadm and 27.3% AKIhosp. Risk factors were age, BMI, arterial hypertension, cardiovascular diseases, diabetes, SOFA, APACHE II, dehydration, sepsis, vasopressor use, radiocontrast, diuresis/h and mechanical ventilation. Independent predictors for AKI were sepsis, diabetes, dehydration, vasopressors on admission, APACHE II and radiocontrast use. Renal replacement therapies (RRT) requirement in AKI patients was 14.8%. Hospital mortality in AKI vs. non-AKI was 38.7% and 23.3% (p < 0.001); and in AKIadm vs. AKIhosp, 41.2% and 37.8% (p = 0.53). CONCLUSIONS: ICU-acquired AKI has high incidence, complications and mortality. Risk factors for AKI and RRT utilization were similar to those described in other epidemiological studies. AKIadm was more frequent than AKIhosp, but had equal prognosis.

[Primary bone lymphoma with multicentric involvement]. / Linfoma primario de hueso con afectación multicéntrica.

Primary bone lymphoma is a rare disease, which usually has a different presentation and evolution than lymphomas of other locations. We are presenting a case of primary bone lymphoma of rapid growth, in cranial and sternal locations. In its evolution, once the excision of the primary lesion of the skull was performed, the patient presented new lesions of rapid growth at the skull and femur level, and progression of pre-sternal lesion. With large B-cell diffuse non-Hodgkin lymphoma pathology, the patient initiated R-CHOPP (cyclophosphamide, doxorubicin, vincristine, prednisone and rituximab) with rapid reduction of all lesions without evidence of progression after the six cycles.

Pandemic 2009 influenza A in Argentina: a study of 337 patients on mechanical ventilation.

RATIONALE: The rapid spread of the 2009 Influenza A (H1N1) around the world underscores the need for a better knowledge of epidemiology, clinical features, outcomes, and mortality predictors, especially in the most severe presentations. OBJECTIVES: To describe these characteristics in patients with confirmed, probable, and suspected viral pneumonia caused by 2009 influenza A (H1N1) admitted to 35 intensive care units with acute respiratory failure requiring mechanical ventilation in Argentina, between June 3 and September 7. METHODS: Inception-cohort study including 337 consecutive adult patients. Data were collected in a form posted on the Argentinian Society of Intensive Care website. MEASUREMENTS AND MAIN RESULTS: Proportions of confirmed, probable, or suspected cases were 39%, 8%, and 53% and had similar outcomes. APACHE II was 18 +/- 7; age 47 +/- 17 years; 56% were male; and 64% had underlying conditions, with obesity (24%), chronic obstructive respiratory disease (18%), and immunosupression (15%) being the most common. Seven percent were pregnant. On admission, patients had severe hypoxemia (Pa(O(2))/Fi(O(2)) 140 [87-200]), extensive lung radiologic infiltrates (2.87 +/- 1.03 quadrants) and bacterial coinfection, (25%; mostly with Streptococcus pneumoniae). Use of adjuvants such as recruitment maneuvers (40%) and prone positioning (13%), and shock (72%) and acute kidney injury requiring hemodialysis (17%), were frequent. Mortality was 46%, and was similar across all ages. APACHE II, lowest Pa(O(2))/Fi(O(2)), shock, hemodialysis, prone positioning, and S. pneumoniae coinfection independently predicted death. CONCLUSIONS: Patients with 2009 influenza A (H1N1) requiring mechanical ventilation were mostly middle-aged adults, often with comorbidities, and frequently developed severe acute respiratory distress syndrome and multiorgan failure requiring advanced organ support. Case fatality rate was accordingly high.

High-Flow Oxygen Therapy Application in Chronic Obstructive Pulmonary Disease Patients With Acute Hypercapnic Respiratory Failure: A Multicenter Study.

OBJECTIVES: To evaluate the effect of high-flow oxygen implementation on the respiratory rate as a first-line ventilation support in chronic obstructive pulmonary disease patients with acute hypercapnic respiratory failure. DESIGN: Multicenter, prospective, analytic observational case series study. SETTING: Five ICUs in Argentina, between August 2018 and September 2019. PATIENTS: Patients greater than or equal to 18 years old with moderate to very severe chronic obstructive pulmonary disease, who had been admitted to the ICU with a diagnosis of hypercapnic acute respiratory failure, were entered in the study. INTERVENTIONS: High-flow oxygen therapy through nasal cannula delivered using high-velocity nasal insufflation. MEASUREMENTS AND MAIN RESULTS: Forty patients were studied, 62.5% severe chronic obstructive pulmonary disease. After the first hour of high-flow nasal cannula implementation, there was a significant decrease of respiratory rate compared with baseline values, with a 27% decline (29 vs 21 breaths/min; p < 0.001). Furthermore, a significant reduction of Paco2 (57 vs 52 mm Hg [7.6 vs 6.9 kPa]; p < 0.001) was observed. The high-flow nasal cannula application failed in 18% patients. In this group, the respiratory rate, pH, and Paco2 showed no significant change during the first hour in these patients. CONCLUSIONS: High-flow oxygen therapy through nasal cannula delivered using high-velocity nasal insufflation was an effective tool for reducing respiratory rate in these chronic obstructive pulmonary disease patients with acute hypercapnic respiratory failure. Early determination and subsequent monitoring of clinical and blood gas parameters may help predict the outcome.

Prevalence of Reverse Triggering in Early ARDS: Results From a Multicenter Observational Study.

BACKGROUND: The prevalence of reverse triggering (RT) in the early phase of ARDS is unknown. RESEARCH QUESTION: During early ARDS, what is the proportion of patients affected by RT, what are its potential predictors, and what is its association with clinical outcomes? STUDY DESIGN AND METHODS: This was prospective, multicenter, and observational study. Patients who met the Berlin definition of ARDS with less than 72 h of mechanical ventilation and had not been paralyzed with neuromuscular blockers were screened. A 30-min recording of respiratory signals was obtained from the patients as soon as they were enrolled, and the number of breaths with RT were counted. RESULTS: One hundred patients were included. ARDS was mild to moderate in 92% of them. The recordings were obtained after a median of 1 day (interquartile range, 1-2 days) of ventilation. Fifty patients had RT, and most of these events (97%) were not associated with breath stacking. Detecting RT was associated with lower tidal volume (Vt) and less opiate infusion. The presence of RT was not associated with time to discontinuation of mechanical ventilation (subdistribution hazard ratio, 1.03; 95% CI, 0.6-1.77), but it possibly was associated with a reduced hospital mortality (hazard ratio, 0.65; 95% CI, 0.57-0.73). INTERPRETATION: Fifty percent of patients receiving assist-control ventilation for mild or moderate ARDS, sedated and nonparalyzed, demonstrate RT without breath stacking on the first day of mechanical ventilation. RT may be associated with low VTS and opiate doses. TRIAL REGISTRY: ClinicalTrials.gov; No.: NCT02732041; URL: www.clinicaltrials.gov.

Effect of PEEP on inspiratory resistance components in patients with acute respiratory distress syndrome ventilated at low tidal volume. / Efecto de la PEEP sobre el componente resistivo inspiratorio en pacientes con sindrome de distrés respiratorio agudo ventilados a bajo volumen corriente.

OBJECTIVE: To describe the behavior of inspiratory resistance components when positive end-expiratory pressure (PEEP) increases in patients with acute respiratory distress syndrome under a protective ventilation strategy. METHODS: In volume-controlled mode, at 6mL/kg and constant flow, end-inspiratory occlusions were performed at 0, 5 10, 15 and 20cmH2O PEEP. Peak, initial and plateau pressure values were assessed, calculating the maximum, minimum and differential resistances. The results were compared by repeated measures analysis of variance (ANOVA) with post hoc Bonferroni correction, considering p < 0.05 significant. RESULTS: The highest maximum resistance was observed at the lowest PEEP levels. The values for 10 and 15cmH2O PEEP significantly differed from those for 5 and 0cmH2O PEEP, whereas that for 20cmH2O PEEP only significantly differed from that for 0cmH2O PEEP (p < 0.05). The minimum resistance behaved similarly to the maximum resistance; the values for PEEP levels from 10cmH2O to 20cmH2O significantly differed from those for 0 and 5cmH2O PEEP (p < 0.05). Differential resistance showed the opposite variation to the maximum and minimum resistances. The only PEEP level that showed significant differences from 0 and 5cmH2O PEEP was 20cmH2O PEEP. Significant differences were also found between 15 and 5cmH2O PEEP (p < 0.05). CONCLUSIONS: During protective ventilation in patients with acute respiratory distress syndrome, the maximum resistance of the respiratory system decreases with PEEP, reflecting the minimum resistance response, whereas differential resistance increases with PEEP.

OBJETIVO: Describir el comportamiento del componente resistivo ante el incremento de la presión positiva espiratoria final (PEEP) en pacientes con síndrome de distrés respiratorio agudo ventilados con una estrategia de ventilación protectora. MÉTODOS: En modo controlada por volumen, a 6mL/Kg y flujo constante se realizaron oclusiones teleinspiratorias a PEEP 0, 5 10, 15 y 20cmH2O. Se obtuvieron valores de presión pico, inicial, plateau y se calculó resistencias máxima, mínima y diferencial. Las comparaciones se realizaron mediante test de ANOVA para muestras relacionadas con corrección post hoc de Bonferroni. Se consideró significativo una p < 0,05. RESULTADOS: La resistencia máxima más elevada se observó en los niveles de PEEP más bajos. Los valores de PEEP 10 y 15cmH2O tuvieron diferencias significativas con PEEP 5 y 0cmH2O, mientras que PEEP 20cmH2O únicamente con PEEP 0cmH2O (p < 0,05). La resistencia mínima tuvo la misma conducta que la resistencia máxima. A partir de PEEP 10cmH2O todos tuvieron diferencias significativas con PEEP 0 y 5cmH2O (p < 0,05). La resistencia diferencial se expresó de manera opuesta a la resistencia máxima y mínima. El único nivel de PEEP que experimentó diferencias significativas con PEEP 0 y 5cmH2O fue PEEP 20cmH2O. También hubo diferencias entre PEEP 15 y PEEP 5cmH2O (p < 0,05). CONCLUSIONES: Durante ventilación protectora en pacientes com síndrome de distrés respiratorio agudo, la resistencia máxima del sistema respiratorio tiene un comportamiento decreciente con la PEEP y refleja la respuesta que tiene la resistencia mínima. Mientras que la resistencia diferencial mantiene su conducta creciente con los valores de PEEP.

Efecto de la PEEP sobre el componente resistivo inspiratorio en pacientes con sindrome de distrés respiratorio agudo ventilados a bajo volumen corriente / Effect of PEEP on inspiratory resistance components in patients with acute respiratory distress syndrome ventilated at low tidal volume

RESUMEN Objetivo: Describir el comportamiento del componente resistivo ante el incremento de la presión positiva espiratoria final (PEEP) en pacientes con síndrome de distrés respiratorio agudo ventilados con una estrategia de ventilación protectora. Métodos: En modo controlada por volumen, a 6mL/Kg y flujo constante se realizaron oclusiones teleinspiratorias a PEEP 0, 5 10, 15 y 20cmH2O. Se obtuvieron valores de presión pico, inicial, plateau y se calculó resistencias máxima, mínima y diferencial. Las comparaciones se realizaron mediante test de ANOVA para muestras relacionadas con corrección post hoc de Bonferroni. Se consideró significativo una p < 0,05. Resultados: La resistencia máxima más elevada se observó en los niveles de PEEP más bajos. Los valores de PEEP 10 y 15cmH2O tuvieron diferencias significativas con PEEP 5 y 0cmH2O, mientras que PEEP 20cmH2O únicamente con PEEP 0cmH2O (p < 0,05). La resistencia mínima tuvo la misma conducta que la resistencia máxima. A partir de PEEP 10cmH2O todos tuvieron diferencias significativas con PEEP 0 y 5cmH2O (p < 0,05). La resistencia diferencial se expresó de manera opuesta a la resistencia máxima y mínima. El único nivel de PEEP que experimentó diferencias significativas con PEEP 0 y 5cmH2O fue PEEP 20cmH2O. También hubo diferencias entre PEEP 15 y PEEP 5cmH2O (p < 0,05). Conclusiones: Durante ventilación protectora en pacientes com síndrome de distrés respiratorio agudo, la resistencia máxima del sistema respiratorio tiene un comportamiento decreciente con la PEEP y refleja la respuesta que tiene la resistencia mínima. Mientras que la resistencia diferencial mantiene su conducta creciente con los valores de PEEP.

ABSTRACT Objective: To describe the behavior of inspiratory resistance components when positive end-expiratory pressure (PEEP) increases in patients with acute respiratory distress syndrome under a protective ventilation strategy. Methods: In volume-controlled mode, at 6mL/kg and constant flow, end-inspiratory occlusions were performed at 0, 5 10, 15 and 20cmH2O PEEP. Peak, initial and plateau pressure values were assessed, calculating the maximum, minimum and differential resistances. The results were compared by repeated measures analysis of variance (ANOVA) with post hoc Bonferroni correction, considering p < 0.05 significant. Results: The highest maximum resistance was observed at the lowest PEEP levels. The values for 10 and 15cmH2O PEEP significantly differed from those for 5 and 0cmH2O PEEP, whereas that for 20cmH2O PEEP only significantly differed from that for 0cmH2O PEEP (p < 0.05). The minimum resistance behaved similarly to the maximum resistance; the values for PEEP levels from 10cmH2O to 20cmH2O significantly differed from those for 0 and 5cmH2O PEEP (p < 0.05). Differential resistance showed the opposite variation to the maximum and minimum resistances. The only PEEP level that showed significant differences from 0 and 5cmH2O PEEP was 20cmH2O PEEP. Significant differences were also found between 15 and 5cmH2O PEEP (p < 0.05). Conclusions: During protective ventilation in patients with acute respiratory distress syndrome, the maximum resistance of the respiratory system decreases with PEEP, reflecting the minimum resistance response, whereas differential resistance increases with PEEP.

Ventilación mecánica en pacientes con falla respiratoria aguda hipoxémica / Mechanical ventilation in patients with acute hypoxemic respiratory failure

Objetivo: Describir las características clínicas de los pacientes internados en la UCI con requerimiento de VMi con FRAH-No SDRA. Evaluar la asociación de la mortalidad con diferentes variables. Diseño: Cohorte de comienzo. Ámbito: Estudio realizado en 2 UCIs argentinas del ámbito privado de la salud, entre el 01/07/2013 y 31/12/2014. Pacientes: De una muestra consecutiva de 2526 pacientes, se incluyeron a 229 mayores de 18 años, que ingresaron a la UCI con requirimiento de VMi por más de 24hs desarrollando FRAH-No SDRA. Variables de interés principales: Se registraron variables demográficas, estadía en VMi y en UCI, variables de programación inicial del respirador, variables de monitoreo y evolución al alta. También se registraron el número y tipo de complicaciones desarrolladas durante el periodo de VMi Resultados: El 70,7% de los ingresos fue por causa médica. El SAPS II fue de 42. El tiempo de VMi y de estadía en UCI fue mayor en los pacientes con delirio (p < 0,0001 en ambos). En el modelo de regresión logística ajustado por severidad de la hipoxemia, la edad (OR 1,02; IC95% 1,002-1,04: p = 0,033) y el shock (OR 2,37; IC95% 1,12-5: p = 0,023) resultaron predictores independientes de mortalidad. Conclusiones: En este grupo de pacientes que requirieron VMi por más de 24 hs y desarrollaron FRAH-No SDRA se encontró una distribución demográfica similar a la descripta por otros reportes. La mortalidad no se relacionó con la severidad de la hipoxemia, mientras que el shock y la edad fueron predictores independientes de mortalidad.

Mechanical ventilation in patients with acute hypoxemic respiratory failure

Objective: To describe the clinical characteristics of patients with AHRF (without ARDS) hospitalized in the ICU who require IMV. To evaluate the association between mortality and different variables. Design: Inception cohort. Scope: This study was conducted in two Argentine ICUs from the private health sector between 07/01/2013 and 12/31/2014. Patients: From a consecutive sample of 2526 patients, 229 individuals aged 18 and upwards were included in the study; they were admitted to the ICU requiring IMV for over 24 hours and developed AHRF (without ARDS). Primary endpoints: Demographic variables and variables associated with the number of days with IMV and at the ICU were documented, as well as the initial setting of the respirator, monitoring variables and evolution at discharge. Likewise, the number and type of complications developed during the period of IMV were documented. Results: 70.7% of admissions were for medical reasons. SAPS II score was 42. The period of IMV and at the ICU was higher in patients with delirium (p<0.0001 in both). In the logistic regression model adjusted by the severity of hypoxemia, age (OR 1.02; 95% CI 1.002-1.04: p = 0.033) and shock (OR 2.37; 95% CI 1.12-5: p = 0.023) acted as independent predictors of mortality. Conclusions: In this group of patients who required IMV for over 24 hours and who developed AHRF (without ARDS) there was a demographic distribution similar to that described in other reports. Mortality was not associated with the severity of hypoxemia, whereas shock and age were independent predictors of mortality.

Linfoma primario de hueso con afectación multicéntrica / Primary bone lymphoma with multicentric involvement

El linfoma primario de hueso es una enfermedad infrecuente, que tiene una presentación y evolución diferente a los linfomas de otras localizaciones. Se presenta un caso de linfoma primario de hueso de localización craneana y esternal de rápido crecimiento. En su evolución, realizada la exéresis de la lesión primaria de calota, presentó aparición de nuevas lesiones de rápido crecimiento a nivel craneano y fémur y progresión de lesión preesternal que, con anatomía patológica de linfoma no Hodgkin difuso de células grandes B, inició R-CHOPP (ciclofosfamida, doxorrubicina, vincristina, prednisona y rituximab) con rápida disminución de todas las lesiones sin evidencia de progresión al cabo de los seis ciclos.

Primary bone lymphoma is a rare disease, which usually has a different presentation and evolution than lymphomas of other locations. We are presenting a case of primary bone lymphoma of rapid growth, in cranial and sternal locations. In its evolution, once the excision of the primary lesion of the skull was performed, the patient presented new lesions of rapid growth at the skull and femur level, and progression of pre-sternal lesion. With large B-cell diffuse non-Hodgkin lymphoma pathology, the patient initiated R-CHOPP (cyclophosphamide, doxorubicin, vincristine, prednisone and rituximab) with rapid reduction of all lesions without evidence of progression after the six cycles.