Partition of respiratory mechanics in patients with acute respiratory distress syndrome and association with outcome: a multicentre clinical study.

PURPOSE: In acute respiratory distress syndrome (ARDS), physiological parameters associated with outcome may help defining targets for mechanical ventilation. This study aimed to address whether transpulmonary pressures (PL), including transpulmonary driving pressure (DPL), elastance-derived plateau PL, and directly-measured end-expiratory PL, are better associated with 60-day outcome than airway driving pressure (DPaw). We also tested the combination of oxygenation and stretch index [PaO2/(FiO2*DPaw)]. METHODS: Prospective, observational, multicentre registry of ARDS patients. Respiratory mechanics were measured early after intubation at 6 kg/ml tidal volume. We compared the predictive power of the parameters for mortality at day-60 through receiver operating characteristic (ROC) and assessed their association with 60-day mortality through unadjusted and adjusted Cox regressions. Finally, each parameter was dichotomized, and Kaplan-Meier survival curves were compared. RESULTS: 385 patients were enrolled 2 [1-4] days from intubation (esophageal pressure and arterial blood gases in 302 and 318 patients). As continuous variables, DPaw, DPL, and oxygenation stretch index were associated with 60-day mortality after adjustment for age and Sequential Organ Failure Assessment, whereas elastance-derived plateau PL was not. DPaw and DPL performed equally in ROC analysis (P = 0.0835). DPaw had the best-fit Cox regression model. When dichotomizing the variables, DPaw ≥ 15, DPL ≥ 12, plateau PL ≥ 24, and oxygenation stretch index < 10 exhibited lower 60-day survival probability. Directly measured end-expiratory PL ≥ 0 was associated with better outcome in obese patients. CONCLUSION: DPL was equivalent predictor of outcome than DPaw. Our study supports the soundness of limiting lung and airway driving pressure and maintaining positive end-expiratory PL in obese patients.

Clinical characteristics, respiratory management, and determinants of oxygenation in COVID-19 ARDS: A prospective cohort study.

PURPOSE: To identify determinants of oxygenation over time in patients with COVID-19 acute respiratory distress syndrome (ARDS); and to analyze their characteristics according to Berlin definition categories. MATERIALS AND METHODS: Prospective cohort study including consecutive mechanically ventilated patients admitted between 3/20/2020-10/31/2020 with ARDS. Epidemiological and clinical data on admission; outcomes; ventilation, respiratory mechanics and oxygenation variables were registered on days 1, 3 and 7 for the entire population and for ARDS categories. RESULTS: 1525 patients aged 61 ± 13, 69% male, met ARDS criteria; most frequent comorbidities were obesity, hypertension, diabetes and respiratory disease. On admission, 331(21%), 849(56%) and 345(23%) patients had mild, moderate and severe ARDS; all received lung-protective ventilation (mean tidal volumes between 6.3 and 6.7 mL/kg PBW) and intermediate PEEP levels (10-11 cmH2O). PaO2/FiO2, plateau pressure, static compliance, driving pressure, ventilation ratio, pH and D-dimer >2 mg/L remained significantly different among the ARDS categories over time. In-hospital mortality was, respectively, 55%, 58% and 70% (p < 0.000). Independent predictors of changes of PaO2/FiO2 over time were BMI; preexistent respiratory disease; D-dimer >2 mg/L; day 1-PEEP, and day 1-ventilatory ratio. CONCLUSION: Hypoxemia in patients with COVID-19-related ARDS is associated with comorbidities, deadspace and activated coagulation markers, and disease severity-reflected by the PEEP level required.

Capacidad estructural, recursos humanos tecnológicos y requerimientos de ventilación mecánica en 58 unidades de cuidados intensivos en argentina durante la pandemia por SARS-CoV-2. Estudio SATICOVID-19 / Structural capacity, technological human resources and mechanical ventilation requirements in 58 intensive care units in Argentina during the SARS-CoV-2 pandemic. A SATICOVID-19 Study

Resumen Durante la pandemia por SARS-CoV-2 hubo un marcado requerimiento de camas de cuidados críticos, insumos y profesionales entrenados para asistir a pacientes con insuficiencia respiratoria grave. La Sociedad Argentina de Terapia Intensiva (SATI) diseñó un estudio para caracterizar estos aspectos en las Unidades de Cuidados Intensivos (UCIs). Estudio multicéntrico, de cohorte prospectiva; las UCIs participantes completaron un formulario al final del estudio (31/10/2020) sobre características hospitalarias, número de camas de áreas críticas pre- e intra-pandemia, incorporación de profesionales, insumos y recursos tecnológicos, y carga de trabajo. Participaron 58 UCIs; 28(48%) de Provincia de Buenos Aires, 22(38%) de Ciudad Autónoma de Bue nos Aires, 10(17%) de otras; 31(53%) UCIs pertenecían al sector público; 23(47%) al privado-seguridad social. En 35/58(60%) hospitales las camas de cuidados críticos aumentaron de 902 a 1575(75%); 37% en UCI y 63% principalmente en Unidad Coronaria y Emergencias-shock room. En 41/55(75%) UCIs se incorporó personal: 27(49%) médicos/as (70% intensivistas), 36(65%) enfermeros/as, 28(51%) kinesiólogos/as, 20(36%) personal de limpieza, y 1(2%) otros/as; 96% de las UCIS reportaron disponer de respiradores suficientes, y 95%, insumos y EPP suficientes. De todos los pacientes en ventilación mecánica invasiva, 55% [43-64] presentaron COVID-19. Se requirió oxigenoterapia como soporte no invasivo en 14% [8-24] de los ingresos por COVID-19. Se registró una importante expansión de las áreas críticas operativas, secundariamente al aumento de camas, personal, y adecuada disponibilidad de respiradores e insumos esenciales. La carga de la enfermedad crítica por COVID-19 fue intensa, constituyendo más de la mitad de los pacientes en ventilación mecánica.

Abstract During the SARS-CoV-2 pandemic, there was a marked requirement for critical care beds, supplies and trained professionals to assist patients with severe respiratory failure. The Argentine Society of Intensive Care (SATI) designed a study to characterize these aspects in intensive care units (ICUs). Multicenter, prospective cohort study; the participating ICUs completed a form at the end of the study (31/10/2020) on hospital characteristics, number of beds in pre- and intra-pandemic critical areas, incorporation of professionals, technological resources, and workload. Fifty-eight ICUs participated; 28(48%) were located in Buenos Aires Province, 22(38%) in Buenos Aires Autonomous City and 10 (17%) in other provinces; 31 (53%) of UCIs belonged to the public sector; 23 (47%) to the private-social security. In 35/58 (60%) of the hospitals critical care beds increased from 902 to 1575 (75%), 37% in ICU and 63% mainly in Coronary Care Unit and Emergency-shock room. In 41/55 (75%) UCIs, staff were incorporated: 27(49%) physicians (70% intensivists), 36 (65%) nurses, 28 (51%) respiratory therapists, 20(36%) cleaning staff, and 1(2%) others. A 96% of the ICUS reported having sufficient ventilators and 95% enough sup plies and PPE. Of all patients on invasive mechanical ventilation, 55% [43-64] had COVID-19. Oxygen therapy was required as noninvasive support in 14% [8-24] of COVID-19 admissions. There was a significant expansion of critical operational areas, secondary to the increase in beds, staff, and adequate availability of ventilators and essential supplies. The burden of critical illness from COVID-19 was intense, with more than half of patients on mechanical ventilation.

[Structural capacity, technological human resources and mechanical ventilation requirements in 58 intensive care units in Argentina during the SARS-CoV-2 pandemic. A SATICOVID-19 Study]. / Capacidad estructural, recursos humanos tecnológicos y requerimientos de ventilación mecánica en 58 unidades de cuidados intensivos en Argentina durante la pandemia por SARS-CoV-2. Estudio SATICOVID-19.

During the SARS-CoV-2 pandemic, there was a marked requirement for critical care beds, supplies and trained professionals to assist patients with severe respiratory failure. The Argentine Society of Intensive Care (SATI) designed a study to characterize these aspects in intensive care units (ICUs). Multicenter, prospective cohort study; the participating ICUs completed a form at the end of the study (31/10/2020) on hospital characteristics, number of beds in pre- and intra-pandemic critical areas, incorporation of professionals, technological resources, and workload. Fifty-eight ICUs participated; 28(48%) were located in Buenos Aires Province, 22(38%) in Buenos Aires Autonomous City and 10 (17%) in other provinces; 31 (53%) of UCIs belonged to the public sector; 23 (47%) to the private-social security. In 35/58 (60%) of the hospitals critical care beds increased from 902 to 1575 (75%), 37% in ICU and 63% mainly in Coronary Care Unit and Emergency-shock room. In 41/55 (75%) UCIs, staff were incorporated: 27(49%) physicians (70% intensivists), 36 (65%) nurses, 28 (51%) respiratory therapists, 20(36%) cleaning staff, and 1(2%) others. A 96% of the ICUS reported having sufficient ventilators and 95% enough supplies and PPE. Of all patients on invasive mechanical ventilation, 55% [43-64] had COVID-19. Oxygen therapy was required as noninvasive support in 14% [8-24] of COVID-19 admissions. There was a significant expansion of critical operational areas, secondary to the increase in beds, staff, and adequate availability of ventilators and essential supplies. The burden of critical illness from COVID-19 was intense, with more than half of patients on mechanical ventilation.

Durante la pandemia por SARS-CoV-2 hubo un marcado requerimiento de camas de cuidados críticos, insumos y profesionales entrenados para asistir a pacientes con insuficiencia respiratoria grave. La Sociedad Argentina de Terapia Intensiva (SATI) diseñó un estudio para caracterizar estos aspectos en las Unidades de Cuidados Intensivos (UCIs). Estudio multicéntrico, de cohorte prospectiva; las UCIs participantes completaron un formulario al final del estudio (31/10/2020) sobre características hospitalarias, número de camas de áreas críticas pre- e intra-pandemia, incorporación de profesionales, insumos y recursos tecnológicos, y carga de trabajo. Participaron 58 UCIs; 28(48%) de Provincia de Buenos Aires, 22(38%) de Ciudad Autónoma de Buenos Aires, 10(17%) de otras; 31(53%) UCIs pertenecían al sector público; 23(47%) al privado-seguridad social. En 35/58(60%) hospitales las camas de cuidados críticos aumentaron de 902 a 1575(75%); 37% en UCI y 63% principalmente en Unidad Coronaria y Emergencias-shock room. En 41/55(75%) UCIs se incorporó personal: 27(49%) médicos/as (70% intensivistas), 36(65%) enfermeros/as, 28(51%) kinesiólogos/as, 20(36%) personal de limpieza, y 1(2%) otros/as; 96% de las UCIS reportaron disponer de respiradores suficientes, y 95%, insumos y EPP suficientes. De todos los pacientes en ventilación mecánica invasiva, 55% [43-64] presentaron COVID-19. Se requirió oxigenoterapia como soporte no invasivo en 14% [8-24] de los ingresos por COVID-19. Se registró una importante expansión de las áreas críticas operativas, secundariamente al aumento de camas, personal, y adecuada disponibilidad de respiradores e insumos esenciales. La carga de la enfermedad crítica por COVID-19 fue intensa, constituyendo más de la mitad de los pacientes en ventilación mecánica.

Clinical characteristics and outcomes of invasively ventilated patients with COVID-19 in Argentina (SATICOVID): a prospective, multicentre cohort study.

BACKGROUND: Although COVID-19 has greatly affected many low-income and middle-income countries, detailed information about patients admitted to the intensive care unit (ICU) is still scarce. Our aim was to examine ventilation characteristics and outcomes in invasively ventilated patients with COVID-19 in Argentina, an upper middle-income country. METHODS: In this prospective, multicentre cohort study (SATICOVID), we enrolled patients aged 18 years or older with RT-PCR-confirmed COVID-19 who were on invasive mechanical ventilation and admitted to one of 63 ICUs in Argentina. Patient demographics and clinical, laboratory, and general management variables were collected on day 1 (ICU admission); physiological respiratory and ventilation variables were collected on days 1, 3, and 7. The primary outcome was all-cause in-hospital mortality. All patients were followed until death in hospital or hospital discharge, whichever occurred first. Secondary outcomes were ICU mortality, identification of independent predictors of mortality, duration of invasive mechanical ventilation, and patterns of change in physiological respiratory and mechanical ventilation variables. The study is registered with ClinicalTrials.gov, NCT04611269, and is complete. FINDINGS: Between March 20, 2020, and Oct 31, 2020, we enrolled 1909 invasively ventilated patients with COVID-19, with a median age of 62 years [IQR 52-70]. 1294 (67·8%) were men, hypertension and obesity were the main comorbidities, and 939 (49·2%) patients required vasopressors. Lung-protective ventilation was widely used and median duration of ventilation was 13 days (IQR 7-22). Median tidal volume was 6·1 mL/kg predicted bodyweight (IQR 6·0-7·0) on day 1, and the value increased significantly up to day 7; positive end-expiratory pressure was 10 cm H2O (8-12) on day 1, with a slight but significant decrease to day 7. Ratio of partial pressure of arterial oxygen (PaO2) to fractional inspired oxygen (FiO2) was 160 (IQR 111-218), respiratory system compliance 36 mL/cm H2O (29-44), driving pressure 12 cm H2O (10-14), and FiO2 0·60 (0·45-0·80) on day 1. Acute respiratory distress syndrome developed in 1672 (87·6%) of patients; 1176 (61·6%) received prone positioning. In-hospital mortality was 57·7% (1101/1909 patients) and ICU mortality was 57·0% (1088/1909 patients); 462 (43·8%) patients died of refractory hypoxaemia, frequently overlapping with septic shock (n=174). Cox regression identified age (hazard ratio 1·02 [95% CI 1·01-1·03]), Charlson score (1·16 [1·11-1·23]), endotracheal intubation outside of the ICU (ie, before ICU admission; 1·37 [1·10-1·71]), vasopressor use on day 1 (1·29 [1·07-1·55]), D-dimer concentration (1·02 [1·01-1·03]), PaO2/FiO2 on day 1 (0·998 [0·997-0·999]), arterial pH on day 1 (1·01 [1·00-1·01]), driving pressure on day 1 (1·05 [1·03-1·08]), acute kidney injury (1·66 [1·36-2·03]), and month of admission (1·10 [1·03-1·18]) as independent predictors of mortality. INTERPRETATION: In patients with COVID-19 who required invasive mechanical ventilation, lung-protective ventilation was widely used but mortality was high. Predictors of mortality in our study broadly agreed with those identified in studies of invasively ventilated patients in high-income countries. The sustained burden of COVID-19 on scarce health-care personnel might have contributed to high mortality over the course of our study in Argentina. These data might help to identify points for improvement in the management of patients in middle-income countries and elsewhere. FUNDING: None. TRANSLATION: For the Spanish translation of the Summary see Supplementary Materials section.

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.

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.

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.

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.

Humidification and heating of inhaled gas in patients with artificial airway. A narrative review. / Acondicionamiento del gas inhalado en pacientes con vía aérea artificial. Revisión narrativa.

Instrumentation of the airways in critical patients (endotracheal tube or tracheostomy cannula) prevents them from performing their function of humidify and heating the inhaled gas. In addition, the administration of cold and dry medical gases and the high flows that patients experience during invasive and non-invasive mechanical ventilation generate an even worse condition. For this reason, a device for gas conditioning is needed, even in short-term treatments, to avoid potential damage to the structure and function of the respiratory epithelium. In the field of intensive therapy, the use of heat and moisture exchangers is common for this purpose, as is the use of active humidification systems. Acquiring knowledge about technical specifications and the advantages and disadvantages of each device is needed for proper use since the conditioning of inspired gases is a key intervention in patients with artificial airway and has become routine care. Incorrect selection or inappropriate configuration of a device can have a negative impact on clinical outcomes. The members of the Capítulo de Kinesiología Intensivista of the Sociedad Argentina de Terapia Intensiva conducted a narrative review aiming to show the available evidence regarding conditioning of inhaled gas in patients with artificial airways, going into detail on concepts related to the working principles of each one.

Acondicionamiento del gas inhalado en pacientes con vía aérea artificial. Revisión narrativa / Humidification and heating of inhaled gas in patients with artificial airway. A narrative review

RESUMEN La instrumentación de la vía aérea del paciente crítico (tubo endotraqueal o cánula de traqueostomía) impide que ésta pueda cumplir con su función de calentar y humidificar el gas inhalado. Sumado a ello la administración de gases medicinales fríos y secos, y los altos flujos a los que se someten los pacientes en ventilación mecánica invasiva o no invasiva, generan una condición aún más desfavorable. Debido a esto es imperativo utilizar algún dispositivo para acondicionar los gases entregados incluso en tratamientos de corta duración con el fin de evitar los daños potenciales sobre la estructura y función del epitelio respiratorio. En el ámbito de terapia intensiva es habitual para esto el uso de intercambiadores de calor y humedad, como así también el uso de sistemas de humidificación activa. Para su correcta utilización es necesario poseer el conocimiento necesario sobre las especificaciones técnicas, ventajas y desventajas de cada uno de estos dispositivos ya que el acondicionamiento de los gases inspirados representa una intervención clave en pacientes con vía aérea artificial y se ha transformado en un cuidado estándar. La selección incorrecta del dispositivo o la configuración inapropiada pueden impactar negativamente en los resultados clínicos. Los integrantes del Capítulo de Kinesiología Intensivista de la Sociedad Argentina de Terapia Intensiva realizaron una revisión narrativa con el objetivo de exponer la evidencia disponible en relación al acondicionamiento del gas inhalado en pacientes con vía aérea artificial, profundizando sobre los conceptos relacionados a los principios de funcionamiento de cada uno.

ABSTRACT Instrumentation of the airways in critical patients (endotracheal tube or tracheostomy cannula) prevents them from performing their function of humidify and heating the inhaled gas. In addition, the administration of cold and dry medical gases and the high flows that patients experience during invasive and non-invasive mechanical ventilation generate an even worse condition. For this reason, a device for gas conditioning is needed, even in short-term treatments, to avoid potential damage to the structure and function of the respiratory epithelium. In the field of intensive therapy, the use of heat and moisture exchangers is common for this purpose, as is the use of active humidification systems. Acquiring knowledge about technical specifications and the advantages and disadvantages of each device is needed for proper use since the conditioning of inspired gases is a key intervention in patients with artificial airway and has become routine care. Incorrect selection or inappropriate configuration of a device can have a negative impact on clinical outcomes. The members of the Capítulo de Kinesiología Intensivista of the Sociedad Argentina de Terapia Intensiva conducted a narrative review aiming to show the available evidence regarding conditioning of inhaled gas in patients with artificial airways, going into detail on concepts related to the working principles of each one.

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.

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.