DSpace Repository :: Browsing by Author "Diaz, Franco"

Browsing by Author "Diaz, Franco"

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Admission to intensive care due to severe bronchiolitis in Colombia: How are we with respect to the rest of Latin America?
(2021) Vásquez-Hoyos, Pablo; Pardo-Carrero, R.; Jaramillo-Bustamante, J.C.; González-Dambrauskas, Sebastián; Carvajal, C.; Diaz, Franco
Scientific Letter
Coqueluche grave: Estado del arte
(Sociedad Medica de Santiago, 2012) Donoso, Alejandro; Arriagada, Daniela; Cruces, Pablo; Diaz, Franco
Pertussis is a contagious disease that has reappeard in the recent years as a public health problem in our country. The clinical presentation has changed especially in the main risk group, children under one year old, evolving in occasions to a highly lethal course called malignant or severe Pertussis. The present review discusses the epidemiology and the mechanisms of pathogenicity, and also describes the risk factors, clinical features and pathophysiology of this particular form. The current evidence and effectiveness of new treatments are described, and a treatment algorithm is proposed.
Fluid overload and outcomes in critically ill children: A single center prospective cohort study.
(Elsevier, 2017) Diaz, Franco; Benfield, Mark; Brown, LaTanya; Hayes, Leslie
OBJECTIVE: To prospectively evaluate the association between fluid overload (FO) and clinical outcomes, mortality, mechanical ventilation (MV), and duration and length of stay in a pediatric intensive care unit (PICU). METHODS: Over a 12-month period, patients who were on MV for >24h or vasoactive support were prospectively included. Demographic and clinical data were recorded. Daily FO was calculated as [(fluid in-fluid out)/admission weight]×100%. Multivariate stepwise logistic regression analysis was used to determine predictors of survival. RESULTS: 224 patients were included; median age was 3.3 (IQR 0.7, 9.9) years, mortality was 15.6%. The median peak FO (PFO) was 12.5% (IQR 5, 25), PFO>10% was present in 55.8% of patients, and PFO>20% was present in 33%. The PFO in non-survivors was 17.8% (IQR 8, 30) and 11% (IQR 4, 23) in survivors (p=0.028). A survival analysis showed no association between PFO and mortality. A multivariate analysis identified vasoactive support, >3 organ failures and acute kidney injury (AKI) but not FO as independent risk factors for mortality. FO was associated with MV duration and PICU length of stay. CONCLUSION: FO is frequent in a general PICU population, but PFO is not an independent risk factor for mortality. Future studies of FO should focus on patients with AKI and multiorgan failure for better classification of severity and potential interventions.
Mapping regional strain in anesthetised healthy subjects during spontaneous ventilation
(2019) Cruces, Pablo; Erranz, Benjamin; Lillo, Felipe; Sarabia, Mauricio; Iturrieta, Pablo; Morales, Felipe; Blaha, Katherine; Medina, Tania; Diaz, Franco; Hurtado, Daniel
Introduction: Breathing produces a phenomenon of cyclic deformation throughout life. Biomechanically, deformation of the lung is measured as strain. Regional strain recently started to be recognised as a tool in the study of lung pathophysiology, but regional lung strain has not been studied in healthy subjects breathing spontaneously without voluntary or pharmacological control of ventilation. Our aim is to generate three-dimensional (3D) regional strain and heterogeneity maps of healthy rat lungs and describe their changes over time. Methods: Micro-CT and image-based biomechanical analysis by finite element approach were carried out in six anaesthetised rats under spontaneous breathing in two different states, at the beginning of the experiment and after 3 hours of observation. 3D regional strain maps were constructed and divided into 10 isovolumetric region-of-interest (ROI) in three directions (apex to base, dorsal to ventral and costal to mediastinal), allowing to regionally analyse the volumetric strain, the strain progression and the strain heterogeneity. To describe in depth these parameters, and systematise their report, we defined regional strain heterogeneity index [1+strain SD ROI(x)]/[1+strain mean ROI(x)] and regional strain progression index [ROI(x)-mean of final strain/ROI(x)-mean of initial strain]. Results: We were able to generate 3D regional strain maps of the lung in subjects without respiratory support, showing significant differences among the three analysed axes. We observed a significantly lower regional volumetric strain in the apex sector compared with the base, with no significant anatomical systematic differences in the other directions. This heterogeneity could not be identified with physiological or standard CT methods. There was no progression of the analysed regional volumetric strain when the two time-points were compared. Discussion: It is possible to map the regional volumetric strain in the lung for healthy subjects during spontaneous breathing. Regional strain heterogeneity and changes over time can be measured using a CT image-based numerical analysis applying a finite element approach. These results support that healthy lung might have significant regional strain and its spatial distribution is highly heterogeneous. This protocol for CT image acquisition and analysis could be a useful tool for helping to understand the mechanobiology of the lung in many diseases.
Mild hypothermia increases pulmonary anti-inflammatory response during protective mechanical ventilation in a piglet model of acute lung injury
(John Wiley & Sons, 2013) Cruces, Pablo; Erranz, Benjamín; Donoso, Donoso; Carvajal, Cristobal; Salomon, Tatiana; Torres, Maria; Diaz, Franco
BACKGROUND: The effects of mild hypothermia (HT) on acute lung injury (ALI) are unknown in species with metabolic rate similar to that of humans, receiving protective mechanical ventilation (MV). We hypothesized that mild hypothermia would attenuate pulmonary and systemic inflammatory responses in piglets with ALI managed with a protective MV. METHODS: Acute lung injury (ALI) was induced with surfactant deactivation in 38 piglets. The animals were then ventilated with low tidal volume, moderate positive end-expiratory pressure (PEEP), and permissive hypercapnia throughout the experiment. Subjects were randomized to HT (33.5°C) or normothermia (37°C) groups over 4 h. Plasma and tissue cytokines, tissue apoptosis, lung mechanics, pulmonary vascular permeability, hemodynamic, and coagulation were evaluated. RESULTS: Lung interleukin-10 concentrations were higher in subjects that underwent HT after ALI induction than in those that maintained normothermia. No difference was found in other systemic and tissue cytokines. HT did not induce lung or kidney tissue apoptosis or influence lung mechanics or markers of pulmonary vascular permeability. Heart rate, cardiac output, oxygen uptake, and delivery were significantly lower in subjects that underwent HT, but no difference in arterial lactate, central venous oxygen saturation, and coagulation test was observed. CONCLUSIONS: Mild hypothermia induced a local anti-inflammatory response in the lungs, without affecting lung function or coagulation, in this piglet model of ALI. The HT group had lower cardiac output without signs of global dysoxia, suggesting an adaptation to the decrease in oxygen uptake and delivery. Studies are needed to determine the therapeutic role of HT in ALI.
Progression of regional lung strain and heterogeneity in lung injury: assessing the evolution under spontaneous breathing and mechanical ventilation
(2020) Hurtado, Daniel E.; Erranz, Benjamín; Lillo, Felipe; Sarabia-Vallejos, Mauricio A.; Iturrieta, Pablo; Morales, Felipe; Blaha, Katherine; Medina, Tania; Diaz, Franco; Cruces, Pablo
Background: Protective mechanical ventilation (MV) aims at limiting global lung deformation and has been associated with better clinical outcomes in acute respiratory distress syndrome (ARDS) patients. In ARDS lungs without MV support, the mechanisms and evolution of lung tissue deformation remain understudied. In this work, we quantify the progression and heterogeneity of regional strain in injured lungs under spontaneous breathing and under MV. Methods: Lung injury was induced by lung lavage in murine subjects, followed by 3 h of spontaneous breathing (SB-group) or 3 h of low Vt mechanical ventilation (MV-group). Micro-CT images were acquired in all subjects at the beginning and at the end of the ventilation stage following induction of lung injury. Regional strain, strain progression and strain heterogeneity were computed from image-based biomechanical analysis. Three-dimensional regional strain maps were constructed, from which a region-of-interest (ROI) analysis was performed for the regional strain, the strain progression, and the strain heterogeneity. Results: After 3 h of ventilation, regional strain levels were significantly higher in 43.7% of the ROIs in the SB-group. Significant increase in regional strain was found in 1.2% of the ROIs in the MV-group. Progression of regional strain was found in 100% of the ROIs in the SB-group, whereas the MV-group displayed strain progression in 1.2% of the ROIs. Progression in regional strain heterogeneity was found in 23.4% of the ROIs in the SB-group, while the MV-group resulted in 4.7% of the ROIs showing significant changes. Deformation progression is concurrent with an increase of non-aerated compartment in SB-group (from 13.3% ± 1.6% to 37.5% ± 3.1%), being higher in ventral regions of the lung. Conclusions: Spontaneous breathing in lung injury promotes regional strain and strain heterogeneity progression. In contrast, low Vt MV prevents regional strain and heterogeneity progression in injured lungs.
Quality and capacity indicators for hospitalized pediatric oncology patients with critical illness: A modified delphi consensus
(2020) Arias, Anita V.; Garza, Marcela; Murthy, Srinivas; Cardenas, Adolfo; Diaz, Franco; Montalvo, Erika; Nielsen, Katie R.; Kortz, Teresa; Sharara-Chami, Rana; Friedrich, Paola; McArthur, Jennifer; Agulnik, Asya
Background: Hospitalized pediatric hematology-oncology (PHO) patients are at high risk for critical illness, especially in resource-limited settings. Unfortunately, there are no established quality indicators to guide institutional improvement for these patients. The objective of this study was to identify quality indicators to include in PROACTIVE (PediatRic Oncology cApaCity assessment Tool for IntensiVe carE), an assessment tool to evaluate the capacity and quality of pediatric critical care services offered to PHO patients. Methods: A comprehensive literature review identified relevant indicators in the areas of structure, performance, and outcomes. An international focus group sorted potential indicators using the framework of domains and subdomains. A modified, three-round Delphi was conducted among 36 international experts with diverse experience in PHO and critical care in high-resource and resource-limited settings. Quality indicators were ranked on relevance and actionability via electronically distributed surveys. Results: PROACTIVE contains 119 indicators among eight domains and 22 subdomains, with high-median importance (≥7) in both relevance and actionability, and ≥80% evaluator agreement. The top five indicators were: (a) A designated PICU area; (b) Availability of a pediatric intensivist; (c) A PHO physician as part of the primary team caring for critically ill PHO patients; (d) Trained nursing staff in pediatric critical care; and (e) Timely PICU transfer of hospitalized PHO patients requiring escalation of care. Conclusions: PROACTIVE is a consensus-derived tool to assess the capacity and quality of pediatric onco-critical care in resource-limited settings. Future endeavors include validation of PROACTIVE by correlating the proposed indicators to clinical outcomes and its implementation to identify service delivery gaps amenable to improvement.
Respiratory mechanics in infants with severe bronchiolitis on controlled mechanical ventilation
(BioMed Central, 2017) Cruces, Pablo; González, Sebastián; Quilodan, Julio; Valenzuela, Jorge; Martínez, Javier; Rivero, Natalia; Arias, Pablo; Diaz, Franco
Background: Analysis of respiratory mechanics during mechanical ventilation (MV) is able to estimate resistive, elastic and inertial components of the working pressure of the respiratory system. Our aim was to discriminate the components of the working pressure of the respiratory system in infants on MV with severe bronchiolitis admitted to two PICU’s. Methods: Infants younger than 1 year old with acute respiratory failure caused by severe bronchiolitis underwent neuromuscular blockade, tracheal intubation and volume controlled MV. Shortly after intubation studies of pulmonary mechanics were performed using inspiratory and expiratory breath hold. The maximum inspiratory and expiratory flow (QI and QE) as well as peak inspiratory (PIP), plateau (PPL) and total expiratory pressures (tPEEP) were measured. Inspiratory and expiratory resistances (RawI and RawE) and Time Constants (KTI and KTE) were calculated. Results: We included 16 patients, of median age 2.5 (1–5.8) months. Bronchiolitis due to respiratory syncytial virus was the main etiology (93.8%) and 31.3% had comorbidities. Measured respiratory pressures were PIP 29 (26–31), PPL 24 (20–26), tPEEP 9 [8–11] cmH2O. Elastic component of the working pressure was significantly higher than resistive and both higher than threshold (tPEEP – PEEP) (P < 0.01). QI was significantly lower than QE [5 (4.27–6.75) v/s 16.5 (12–23.8) L/min. RawI and RawE were 38.8 (32–53) and 40.5 (22–55) cmH2O/L/s; KTI and KTE [0.18 (0.12–0.30) v/s 0.18 (0.13–0.22) s], and KTI:KTE ratio was 1:1.04 (1:0.59–1.42). Conclusions: Analysis of respiratory mechanics of infants with severe bronchiolitis receiving MV shows that the elastic component of the working pressure of the respiratory system is the most important. The elastic and resistive components in conjunction with flow profile are characteristic of restrictive diseases. A better understanding of lung mechanics in this group of patients may lead to change the traditional ventilatory approach to severe bronchiolitis.
Ruptura gástrica idiopática en niño preescolar. Informe de un caso
(Sociedad Argentina de Pediatría, 2012) Donoso, Alejandro; Arriagada, Daniela; Cruces, Pablo; Diaz, Franco
Idiopathic gastric rupture is rare in children. Most of them occur in newborn. The authors report the case of a 2-year-old female toddler with no significant medical records. Clinical picture began 48 h before with abdominal pain, nausea and vomiting. She was admitted to the Emergency Room in poor general condition, with abdominal distension and rebound tenderness. Laparotomy was performed immediately show-ing multiple perforations in the posterior wall of the stomach. Partial gastrectomy was performed. Afterwards, she was admitted to ICU in shock. She received mechanical ventilation, intravenous fluid administration (260 ml/kg in 12 h), vasoactive support and antibacterial therapy (cefotaxime and metronidazole). Laboratory showed leukopenia and thrombocytopenia. Etiological study was entirely negative for toxic and drug consumption. Collagen disease was ruled out and serum level of gastrin was normal. Her post operative course was characterized by persistent fever caused by left subphrenic collection (positive culture for Candida galabrata). Peritoneal lavage via laparotomy and percutaneous drainage of the residual collections were performed. She completed 3 weeks of antibacterial and antifungal therapies with adequate outcome. Her follow-up in 12 months was uneventful.
Surfactant deactivation in a pediatric model induces hypovolemia and fluid shift to the extravascular lung compartment
(John Wiley & Sons, 2013) Diaz, Franco; Erranz, Benjamín; Donoso, Alejandro; Carvajal, Cristobal; Salomon, Tatiana; Torres, Maria; Cruces, Pablo
BACKGROUND: Surfactant deficiency is the pivotal abnormality in Neonatal and Acute Respiratory Distress Syndrome. Surfactant deactivation can produce hypoxemia, loss of lung compliance, and pulmonary edema, but its circulatory consequences are less understood. OBJECTIVE: To describe the sequential hemodynamic changes and pulmonary edema formation after surfactant deactivation in piglets. METHODS: Surfactant deactivation was induced by tracheal instillation of polysorbate 20 in 15 anesthetized and mechanically ventilated Large White piglets. The hemodynamic consequences of surfactant deactivation were assessed at 30, 120, and 240 min by transpulmonary thermodilution and traditional methods. RESULTS: Surfactant deactivation caused hypoxemia, reduced lung compliance, and progressively increased lung water content (P < 0.01). Early hypovolemia was observed, with reductions of the global end-diastolic volume and stroke volume (P < 0.05). Reduced cardiac output was observed at the end of the study (P < 0.05). Standard monitoring was unable to detect these early preload alterations. Surprisingly, the bronchoalveolar protein content was greatly increased at the end of the study compared with baseline levels (P < 0.01). This finding was inconsistent with the notion that the pulmonary edema induced by surfactant deactivation was exclusively caused by high surface tension. CONCLUSIONS: Hypovolemia develops early after surfactant deactivation, in part due to the resulting fluid shift from the intravascular compartment to the lungs.
Variability in care for children with severe acute asthma in Latin America
(2021) Monteverde-Fernandez, Nicolas; Diaz, Franco; Vásquez-Hoyos, Pablo; Rotta, Alexandre T.; González-Dambrauskas, Sebastián; LARed Network
Background: Care variability for children with severe acute asthma has been well documented in high-income countries, yet data from low- and middle-income regions are lacking. We sought to characterize the magnitude of practice variability in the care of Latin American children to identify opportunities for standardization of care. Methods: A cross-sectional study performed through a retrospective analysis of contemporaneously collected data of children with severe acute asthma admitted to a center contributing to the LARed Network registry between May 2017 and May 2019. Centers were grouped by geographic location: Atlantic (AT), South Pacific (SP), and North Central (NC). Results: Among 434 children, most received care in hospitals in the AT group (54% [235/434]), followed by the NC (23% [101/434]) and SP (23% [98/434]) groups. The majority of children in the AT (92% [215/235]) and SP (91% [89/98]) groups received nebulized salbutamol/albuterol, while metered-dose inhalers were preferred in the NC group (72% [73/101]). There was a wide variation in the use of antibiotics: AT (57% [135/235]), SP (48% [47/98]), and NC (14% [14/101]). The same was true for ipratropium bromide: AT (67% [157/235]), SP (90% [88/98]), and NC (17% [17/101]), and aminophylline: AT (57% [135/235]), NC (5% [5/101]), and SP (0% [0/98]). High-flow nasal cannula was the preferred respiratory support modality in the AT (60% [141/235]) and NC (40% [40/101]) groups, while bilevel positive airway pressure (BiPAP) use was more common in the SP group (80% [78/98]). Conclusion: We identified significant variability in care for severe acute asthma. Our findings will help to inform the design of future studies, quality improvement initiatives, and development of practice guidelines within Latin America.
Ventilatory strategies against child with acute respiratory distress syndrome and severe hypoxemia
(Unidad de Congresos del Centro Médico Nacional, 2015) Donoso, Alejandro; Arriagada, Daniela; Diaz, Franco; Cruces, Pablo
In this review, we assemble the fundamental concepts of the use of mechanical ventilation (MV) in children with acute respiratory failure (ARDS) and refractory hypoxemia. We also discusses topics of protective ventilation and recruitment potential, and specifically examine the options of ventilation and/or maneuvers designed to optimize the non-aerated lung tissue: alveolar recruitment maneuvers, positive end-expiratory pressure (PEEP) titulation, high frequency oscillatory ventilation (HFOV), airway pressure release ventilation (APRV), aimed at correcting the mismatch ventilation/perfusion (V/Q): use of prone position. The only pharmacological intervention analyzed is the use of neuromuscular blockers. In clinical practice, the protective MV concept involves using an individual adjustment of the PEEP and volume tidal (V(T)). Use of recruitment maneuvers and PEEP downward titration can improve lung function in patients with ARDS and severe hypoxemia. We must keep in mind HFOV instauration as early as possible in response to failure of MV. The use of early and prolonged prone can improve gas exchange in hopes of a better control of what caused the use of MV.

Browsing by Author "Diaz, Franco"

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