Pendelluft in hypoxemic patients resuming spontaneous breathing: proportional modes versus pressure support ventilation.

BACKGROUND: Internal redistribution of gas, referred to as pendelluft, is a new potential mechanism of effort-dependent lung injury. Neurally-adjusted ventilatory assist (NAVA) and proportional assist ventilation (PAV +) follow the patient's respiratory effort and improve synchrony compared with pressure support ventilation (PSV). Whether these modes could prevent the development of pendelluft compared with PSV is unknown. We aimed to compare pendelluft magnitude during PAV + and NAVA versus PSV in patients with resolving acute respiratory distress syndrome (ARDS). METHODS: Patients received either NAVA, PAV + , or PSV in a crossover trial for 20-min using comparable assistance levels after controlled ventilation (> 72 h). We assessed pendelluft (the percentage of lost volume from the non-dependent lung region displaced to the dependent region during inspiration), drive (as the delta esophageal swing of the first 100 ms [ΔPes 100 ms]) and inspiratory effort (as the esophageal pressure-time product per minute [PTPmin]). We performed repeated measures analysis with post-hoc tests and mixed-effects models. RESULTS: Twenty patients mechanically ventilated for 9 [5-14] days were monitored. Despite matching for a similar tidal volume, respiratory drive and inspiratory effort were slightly higher with NAVA and PAV + compared with PSV (ΔPes 100 ms of -2.8 [-3.8--1.9] cm H2O, -3.6 [-3.9--2.4] cm H2O and -2.1 [-2.5--1.1] cm H2O, respectively, p < 0.001 for both comparisons; PTPmin of 155 [118-209] cm H2O s/min, 197 [145-269] cm H2O s/min, and 134 [93-169] cm H2O s/min, respectively, p < 0.001 for both comparisons). Pendelluft magnitude was higher in NAVA (12 ± 7%) and PAV + (13 ± 7%) compared with PSV (8 ± 6%), p < 0.001. Pendelluft magnitude was strongly associated with respiratory drive (ß = -2.771, p-value < 0.001) and inspiratory effort (ß = 0.026, p < 0.001), independent of the ventilatory mode. A higher magnitude of pendelluft in proportional modes compared with PSV existed after adjusting for PTPmin (ß = 2.606, p = 0.010 for NAVA, and ß = 3.360, p = 0.004 for PAV +), and only for PAV + when adjusted for respiratory drive (ß = 2.643, p = 0.009 for PAV +). CONCLUSIONS: Pendelluft magnitude is associated with respiratory drive and inspiratory effort. Proportional modes do not prevent its occurrence in resolving ARDS compared with PSV.

Dynamic relative regional lung strain estimated by computed tomography and electrical impedance tomography in ARDS patients.

BACKGROUND: In the acute distress respiratory syndrome (ARDS), specific lung regions can be exposed to excessive strain due to heterogeneous disease, gravity-dependent lung collapse and injurious mechanical ventilation. Computed tomography (CT) is the gold standard for regional strain assessment. An alternative tool could be the electrical impedance tomography (EIT). We aimed to determine whether EIT-based methods can predict the dynamic relative regional strain (DRRS) between two levels of end-expiratory pressure (PEEP) in gravity-non-dependent and dependent lung regions. METHODS: Fourteen ARDS patients underwent CT and EIT acquisitions (at end-inspiratory and end-expiratory) at two levels of PEEP: a low-PEEP based on ARDS-net strategy and a high-PEEP titrated according to EIT. Three EIT-based methods for DRRS were compared to relative CT-based strain: (1) the change of the ratio between EIT ventilation and end-expiratory lung impedance in arbitrary units ([ΔZAU low-PEEP/EELIAU low-PEEP]/[ΔZAU high-PEEP/EELIAU high-PEEP]), (2) the change of ΔZ/EELI ratio calibrated to mL ([ΔZml low-PEEP/EELIml low-PEEP]/[ΔZml high-PEEP/EELIml high-PEEP]) using CT data, and (3) the relative change of ∆ZAU (∆ZAU low-PEEP/∆ZAU high-PEEP). We performed linear regressions analysis and calculated bias and limits of agreement to assess the performance of DRRS by EIT in comparison with CT. RESULTS: The DRRS assessed by (ΔZml low-PEEP/EELIml low-PEEP)/(ΔZml high-PEEP/EELIml high-PEEP) and ∆ZAU low-PEEP/∆ZAU high-PEEP showed good relationship and agreement with the CT method (R2 of 0.9050 and 0.8679, respectively, in non-dependent region; R2 of 0.8373 and 0.6588, respectively, in dependent region; biases ranging from - 0.11 to 0.51 and limits of agreement ranging from - 0.73 to 1.16 for both methods and lung regions). Conversely, DRRS based on EELIAU ([ΔZAU low-PEEP/EELIAU low-PEEP]/[ΔZAU high-PEEP/EELIAU high-PEEP]) exhibited a weak negative relationship and poor agreement with the CT method for both non-dependent and dependent regions (R2 ~ 0.3; bias of 3.11 and 2.08, and limits of agreement of - 2.13 to 8.34 and from - 1.49 to 5.64, respectively). CONCLUSION: Changes in DRRS during a PEEP trial in ARDS patients could be monitored using EIT, based on changes in ΔZmL/EELIml and ∆ZAU. The relative change ∆ZAU offers the advantage of not requiring CT data for calibration.

Inflammatory biomarkers and pendelluft magnitude in ards patients transitioning from controlled to partial support ventilation.

The transition from controlled to partial support ventilation is a challenge in acute respiratory distress syndrome (ARDS) patients due to the risks of patient-self-inflicted lung injury. The magnitude of tidal volume (VT) and intrapulmonary dyssynchrony (pendelluft) are suggested mechanisms of lung injury. We conducted a prospective, observational, physiological study in a tertiary academic intensive care unit. ARDS patients transitioning from controlled to partial support ventilation were included. On these, we evaluated the association between changes in inflammatory biomarkers and esophageal pressure swing (ΔPes), transpulmonary driving pressure (ΔPL), VT, and pendelluft. Pendelluft was defined as the percentage of the tidal volume that moves from the non-dependent to the dependent lung region during inspiration, and its frequency at different thresholds (- 15, - 20 and - 25%) was also registered. Blood concentrations of inflammatory biomarkers (IL-6, IL-8, TNF-α, ANGPT2, RAGE, IL-18, Caspase-1) were measured before (T0) and after 4-h (T4) of partial support ventilation. Pendelluft, ΔPes, ΔPL and VT were recorded. Nine out of twenty-four patients (37.5%) showed a pendelluft mean ≥ 10%. The mean values of ΔPes, ΔPL, and VT were - 8.4 [- 6.7; - 10.2] cmH2O, 15.2 [12.3-16.5] cmH2O and 8.1 [7.3-8.9] m/kg PBW, respectively. Significant associations were observed between the frequency of high-magnitude pendelluft and IL-8, IL-18, and Caspase-1 changes (T0/T4 ratio). These results suggest that the frequency of high magnitude pendelluft may be a potential determinant of inflammatory response related to inspiratory efforts in ARDS patients transitioning to partial support ventilation. Future studies are needed to confirm these results.

Clinical characteristics and in-hospital mortality of patients with COVID-19 in Chile: A prospective cohort study.

AIMS OF THIS STUDY: To describe the Latin American population affected by COVID-19, and to determine relevant risk factors for in-hospital mortality. METHODS: We prospectively registered relevant clinical, laboratory, and radiological data of adult patients with COVID-19, admitted within the first 100 days of the pandemic from a single teaching hospital in Santiago, Chile. The primary outcome was in-hospital mortality. Secondary outcomes included the need for respiratory support and pharmacological treatment, among others. We combined the chronic disease burden and the severity of illness at admission with predefined clinically relevant risk factors. Cox regression models were used to identify risk factors for in-hospital mortality. RESULTS: We enrolled 395 adult patients, their median age was 61 years; 62.8% of patients were male and 40.1% had a Modified Charlson Comorbidity Index (MCCI) ≥5. Their median Sequential Organ Failure Assessment (SOFA) score was 3; 34.9% used a high-flow nasal cannula and 17.5% required invasive mechanical ventilation. The in-hospital mortality rate was 14.7%. In the multivariate analysis, were significant risk factors for in-hospital mortality: MCCI ≥5 (HR 4.39, P < .001), PaO2 /FiO2 ratio ≤200 (HR 1.92, P = .037), and advanced chronic respiratory disease (HR 3.24, P = .001); pre-specified combinations of these risk factors in four categories was associated with the outcome in a graded manner. CONCLUSIONS AND CLINICAL IMPLICATIONS: The relationship between multiple prognostic factors has been scarcely reported in Latin American patients with COVID-19. By combining different clinically relevant risk factors, we can identify COVID-19 patients with high-, medium- and low-risk of in-hospital mortality.

Estimation of changes in cyclic lung strain by electrical impedance tomography: Proof-of-concept study.

RATIONALE: Cyclic strain may be a determinant of ventilator-induced lung injury. The standard for strain assessment is the computed tomography (CT), which does not allow continuous monitoring and exposes to radiation. Electrical impedance tomography (EIT) is able to monitor changes in regional lung ventilation. In addition, there is a correlation between mechanical deformation of materials and detectable changes in its electrical impedance, making EIT a potential surrogate for cyclic lung strain measured by CT (StrainCT ). OBJECTIVES: To compare the global StrainCT with the change in electrical impedance (ΔZ). METHODS: Acute respiratory distress syndrome patients under mechanical ventilation (VT 6 mL/kg ideal body weight with positive end-expiratory pressure 5 [PEEP 5] and best PEEP according to EIT) underwent whole-lung CT at end-inspiration and end-expiration. Biomechanical analysis was used to construct 3D maps and determine StrainCT at different levels of PEEP. CT and EIT acquisitions were performed simultaneously. Multilevel analysis was employed to determine the causal association between StrainCT and ΔZ. Linear regression models were used to predict the change in lung StrainCT between different PEEP levels based on the change in ΔZ. MAIN RESULTS: StrainCT was positively and independently associated with ΔZ at global level (P < .01). Furthermore, the change in StrainCT (between PEEP 5 and Best PEEP) was accurately predicted by the change in ΔZ (R2 0.855, P < .001 at global level) with a high agreement between predicted and measured StrainCT . CONCLUSIONS: The change in electrical impedance may provide a noninvasive assessment of global cyclic strain, without radiation at bedside.

[Neisseria meningitidis pneumonia. A case report]. / Neumonía bacterémica por Neisseria meningitidis: Primer caso reportado en Chile y revisión bibliográfica.

Few cases of bacteremic pneumonia by Neisseria meningitidis (NM) have been described worldwide; mostly in elderly patients or those with comorbidities. They appear clinically indistinguishable from other acute infectious pneumoniae, that do not develope the syndrome of meningococcemia. We report a 17-years-old male, without prior medical history, consulting in the emergency department with a 7-day history of productive cough, right pleural pain, fever and dyspnea. He was admitted to the ICU due to septic shock and respiratory distress. He was managed with vasoactive drugs and prone positioning ventilation for 48 hours. Chest radiography showed a right superior lobe condensation. The electrocardiogram and echocardiogram suggested septic myocarditis. Blood cultures demonstrated the presence of serogroup W135-NM. A lumbar puncture ruled out meningitis, and a 10-day ceftriaxone therapy was completed favorably.

Neumonía bacterémica por Neisseria meningitidis: primer caso reportado en Chile y revisión bibliográfica / Neisseria meningitidis pneumonia. a case report

Few cases of bacteremic pneumonia by Neisseria meningitidis (NM) have been described worldwide; mostly in elderly patients or those with comorbidities. They appear clinically indistinguishable from other acute infectious pneumoniae, that do not develope the syndrome of meningococcemia. We report a 17-years-old male, without prior medical history, consulting in the emergency department with a 7-day history of productive cough, right pleural pain, fever and dyspnea. He was admitted to the ICU due to septic shock and respiratory distress. He was managed with vasoactive drugs and prone positioning ventilation for 48 hours. Chest radiography showed a right superior lobe condensation. The electrocardiogram and echocardiogram suggested septic myocarditis. Blood cultures demonstrated the presence of serogroup W135-NM. A lumbar puncture ruled out meningitis, and a 10-day ceftriaxone therapy was completed favorably.

[Infections by Listeria monocytogenes]. / Infecciones por Listeria monocytogenes, una experiencia de dos décadas: A two decade experience.

BACKGROUND: Listeria monocytogenes infections have been poorly characterized in Chile. AIM: To evaluate clinical manifestations and risk factors associated to a fatal outcome in a series of patients. METHODS: retrospective analysis of cases from 1991 to 2012. RESULTS: Twenty three cases were identified, including 2 diagnosed after prolonged hospitalization (8.7%) with an average age of 68.4 years (range 44-90). Known predisposing factors were age > 65 years (60.9%), diabetes mellitus (40.9%), and immunosuppression (27.3%). Most cases presented after 2003 (70%). No cases associated with neonates, pregnancy or HIV infections were recorded. Patients presented with central nervous system (CNS) infection (39%), including 8 cases of meningitis and one of rhomboencephalitis; bacteremia (43.5%), including one case with endocarditis; abscesses (8.7%); and other infections (spontaneous bacterial peritonitis and pneumonia; 8.7%). Risky food consumption was found in 80% of those asked about it. Predominant clinical manifestations were fever (90.9%), and confusion (63.6%). CNS infections were associated to headache (OR 21, p < 0.05), nausea and vomiting (OR 50, p < 0.01). Only 45.5% received initial appropriate empirical therapy and 36.4% a synergistic combination. Eight patients died (34.8%), this outcome was associated to bacteremia (OR 8.25; IC95 1.2-59 p < 0.05). CONCLUSIONS: L. monocytogenes infections appear to be increasing in Chile, causing infections in different sites, attacking vulnerable patients, and have a high case-fatality ratio, especially among those with bacteremia.

Infecciones por Listeria monocytogenes, una experiencia de dos décadas: A two decade experience / Infections by Listeria monocytogenes

Background: Listeria monocytogenes infections have been poorly characterized in Chile. ^4im: To evaluate clinical manifestations and risk factors associated to a fatal outcome in a series of patients. Methods: retrospective analysis of cases from 1991 to 2012. Results: Twenty three cases were identified, including 2 diagnosed after prolonged hospitalization (8.7%) with an average age of 68.4 years (range 44-90). Known predisposing factors were age > 65 years (60.9%), diabetes mellitus (40.9%), and immunosuppression (27.3%). Most cases presented after 2003 (70%). No cases associated with neonates, pregnancy or HIV infections were recorded. Patients presented with central nervous system (CNS) infection (39%), including 8 cases of meningitis and one of rhomboencephalitis; bacteremia (43.5%), including one case with endocarditis; abscesses (8.7%); and other infections (spontaneous bacterial peritonitis and pneumonia; 8.7%). Risky food consumption was found in 80% of those asked about it. Predominant clinical manifestations were fever (90.9%), and confusion (63.6%). CNS infections were associated to headache (OR 21, p < 0.05), nausea and vomiting (OR 50, p < 0.01). Only 45.5% received initial appropriate empirical therapy and 36.4% a synergistic combination. Eight patients died (34.8%), this outcome was associated to bacteremia (OR 8.25; IC95 1.2-59 p < 0.05). Conclusions: L. monocytogenes infections appear to be increasing in Chile, causing infections in different sites, attacking vulnerable patients, and have a high case-fatality ratio, especially among those with bacteremia.

Introducción: Las infecciones por Listeria monocytogenes representan una zoonosis con escasa caracterización clínica en Chile. Objetivo: Analizar manifestaciones clínicas y factores de riesgo asociados a desenlace fatal. Pacientes yMétodos: Estudio retrospectivo de casos desde 1991 a 2012. Resultados: Se identificaron 23 casos, dos de ellos de aparición nosocomial (8,7%). La edad promedio fue 68,4 años (rango 44-90). El 70% de los casos ha ocurrido desde el año 2003. Los factores predisponentes más frecuentes fueron edad > 65 años (60,9%), diabetes mellitus (40,9%) e inmunosupresión (27,3%). No se encontraron casos asociados a embarazo, infección por VIH o neonatos. La presentación clínica correspondió a infección del SNC (39%,) con ocho casos de meningitis y uno de romboencefalitis (5%); bacteriemias (43,5%) con un caso de endocarditis infecciosa; abscesos (8,7%) y un caso de neumonía y de peritonitis bacteriana espontánea (8,7%). El consumo de alimentos de riesgo fue buscado en cinco pacientes y confirmado en cuatro (80%). Las manifestaciones clínicas más frecuentes fueron fiebre (90,9%) y compromiso de conciencia (63,6%). La presencia de cefalea (OR 21 p < 0,05), o náuseas y/o vómitos (OR 50 p < 0,01) se asociaron en forma significativa a infección del SNC. Sólo 45,5% recibió una terapia antimicrobiana empírica inicial adecuada y 36,4% un esquema sinérgico. Ocho pacientes fallecieron (34,8%), desenlace que estuvo asociado a bacteriemia (OR 8,25; IC95 1,2-59 p < 0,05). Conclusiones: Las infecciones por L. monocytogenes parecen estar aumentando lentamente en Chile, producen infecciones en diferentes parénquimas, afectan a pacientes vulnerables, y tienen una alta letalidad, especialmente en el subgrupo con bacteriemia.

[Bacteremic colangitis in adults in a general hospital in Chile]. / Colangitis bacteriémica en adultos en un hospital general en Chile.

BACKGROUND: Some aspects of bacteremic cholangitis are unknown in Chile. AIM: To gather more information on clinical, microbiological aspects as well as risk factors for ICU admission, recurrence and antimicrobial resistance. MATERIAL AND METHODS: A retrospective research was performed using medical records of adult patients in a general hospital. RESULTS: Between 2006-2012, 22 patients with 29 bacteremic events were identified. Previous cholangitis events were reported by 27.3%, 45.5% had recent admissions and, 50% had used antimicrobial compounds. Coledocholithiasis was the most common cause of obstruction (45.5%) followed by cancer (36.4%). One third developed shock (31%), the only factor associated with ICU admission (OR 30, p < 0.05). In 24 of the 29 bacteremic events, the biliary tract was intervened (82.8%) and in 80.8% during the first 72 hours. Gram negative bacilli were predominant (> 80%) and some infrequent agents such as Staphylococcus warneri, Shewanella spp. and, Aeromonas spp. were observed. Among enteric gram negative bacilli, 29.2% presented fluoroquinolone resistance and, 26.1% resistance to third generation cephalosporins, both associated with previous endoscopic retrograde cholangiography (OR 35 and 16.5, respectively p < 0.05). A favorable response was observed in 93.1% of bacte-remic events but in 31.8% of patients cholangitis recurred with or without bacteremia. Recurrence was associated to recent admission (OR 16.5, p = 0.01) and in all cases occurred before 81 days. In-hospital mortality was 9.1% (n = 2), but in only one case associated to sepsis. Average length of stay (LOS) was 17.8 days. CONCLUSIONS: Early intervention of the biliary tract allows a favorable response in patients affected by bacteremic cholangitis, but this condition use intensive care resources, had a prolonged LOS, a recurrent pattern, and is associated with several bacterial species, some of them resistant.

Colangitis bacteriémica en adultos en un hospital general en Chile / Bacteremic colangitis in adults in a general hospital in Chile

Background: Some aspects of bacteremic cholangitis are unknown in Chile. Aim: To gather more information on clinical, microbiological aspects as well as risk factors for ICU admission, recurrence and antimicrobial resistance. Material and Methods: A retrospective research was performed using medical records of adult patients in a general hospital. Results: Between 2006-2012, 22 patients with 29 bacteremic events were identified. Previous cholangitis events were reported by 27.3%, 45.5% had recent admissions and, 50% had used antimicrobial compounds. Coledocholithiasis was the most common cause of obstruction (45.5%) followed by cancer (36.4%). One third developed shock (31%), the only factor associated with ICU admission (OR 30, p < 0.05). In 24 of the 29 bacteremic events, the biliary tract was intervened (82.8%) and in 80.8% during the first 72 hours. Gram negative bacilli were predominant (> 80%) and some infrequent agents such as Staphylococcus warneri, Shewanella spp. and, Aeromonas spp. were observed. Among enteric gram negative bacilli, 29.2% presented fluoroquinolone resistance and, 26.1% resistance to third generation cephalosporins, both associated with previous endoscopic retrograde cholangiography (OR 35 and 16.5, respectively p < 0.05). A favorable response was observed in 93.1% of bacte-remic events but in 31.8% of patients cholangitis recurred with or without bacteremia. Recurrence was associated to recent admission (OR 16.5, p = 0.01) and in all cases occurred before 81 days. In-hospital mortality was 9.1% (n = 2), but in only one case associated to sepsis. Average length of stay (LOS) was 17.8 days. Conclusions: Early intervention of the biliary tract allows a favorable response in patients affected by bacteremic cholangitis, but this condition use intensive care resources, had a prolonged LOS, a recurrent pattern, and is associated with several bacterial species, some of them resistant.

Introducción: La información sobre los cuadros de colangitis aguda bacteriémica es fragmentaria en Chile. Objetivo: Analizar las características clínicas, evolución, microbiología y factores de riesgo asociados a ingreso a UCI, recurrencia y resistencia antimicrobiana. Pacientes y Métodos: Estudio retrospectivo descriptivo con adultos atendidos entre el 2006 y el 2012 en un hospital general. Resultados: Se identificaron 22 pacientes con 29 episodios de bacteriemia. Un 27,3% tenía historia previa de colangitis aguda, 45,5% de hospitalizaciones en los últimos tres meses y 50% recibió previamente antimicrobianos. La coledocolitiasis fue la causa más frecuente de obstrucción (45,5%) y las neoplasias ocuparon el segundo lugar (36,4%). El 31% desarrolló shock hemodinámico y fue el factor determinante para ingresar a la UCI (OR 30, p < 0,01) En 24 de los 29 eventos de colangitis bacteriémica se efectuaron intervenciones sobre la vía biliar (VB) o complicaciones asociadas (82,8%), las que se realizaron predominantemente en las primeras 72 h de hospitalización (80,8%). Las especies bacterianas mayoritarias fueron bacilos gramnegativos entéricos o no fermentadores (> 80% del total) y se observaron agentes inusuales como Staphylococcus warneri, Shewanella spp y Aeromonas spp. Entre los bacilos gramnegativos entéricos, 29,2% presentó resistencia a fluoroquinolonas y 26,1 % a cefalosporinas de tercera generación, fenómenos asociados al antecedente de colangiografía endoscópica retrógrada (OR 35 y 16,5 respectivamente, p < 0,05). El 93,1% de los eventos de bacteriemia tuvo una respuesta favorable pero 31,8% de los pacientes presentó recu-rrencia de colangitis, con o sin bacteriemia, un hecho asociado a hospitalización reciente (OR 16,5, p = 0,01) y que se dio en todos los casos antes de 81 días. Dos pacientes con cáncer fallecieron en la misma hospitalización (9,1%), aunque uno solo de ellos en forma atribuible a la infección. La estadía hospitalaria promedio fue de 17,8 días. Conclusiones: Con la intervención precoz sobre la VB, los cuadros de colangitis bacteriémica han logrado una baja letalidad pero usan recursos intensivos, tienen una estadía prolongada, un patrón recurrente, pueden estar asociados a cáncer y a una diversidad de agentes bacterianos, algunos de ellos resistentes.