Capillary refill time response to a fluid challenge or a vasopressor test: an observational, proof-of-concept study.

BACKGROUND: Several studies have validated capillary refill time (CRT) as a marker of tissue hypoperfusion, and recent guidelines recommend CRT monitoring during septic shock resuscitation. Therefore, it is relevant to further explore its kinetics of response to short-term hemodynamic interventions with fluids or vasopressors. A couple of previous studies explored the impact of a fluid bolus on CRT, but little is known about the impact of norepinephrine on CRT when aiming at a higher mean arterial pressure (MAP) target in septic shock. We designed this observational study to further evaluate the effect of a fluid challenge (FC) and a vasopressor test (VPT) on CRT in septic shock patients with abnormal CRT after initial resuscitation. Our purpose was to determine the effects of a FC in fluid-responsive patients, and of a VPT aimed at a higher MAP target in chronically hypertensive fluid-unresponsive patients on the direction and magnitude of CRT response. METHODS: Thirty-four septic shock patients were included. Fluid responsiveness was assessed at baseline, and a FC (500 ml/30 mins) was administered in 9 fluid-responsive patients. A VPT was performed in 25 patients by increasing norepinephrine dose to reach a MAP to 80-85 mmHg for 30 min. Patients shared a multimodal perfusion and hemodynamic monitoring protocol with assessments at at least two time-points (baseline, and at the end of interventions). RESULTS: CRT decreased significantly with both tests (from 5 [3.5-7.6] to 4 [2.4-5.1] sec, p = 0.008 after the FC; and from 4.0 [3.3-5.6] to 3 [2.6 -5] sec, p = 0.03 after the VPT. A CRT-response was observed in 7/9 patients after the FC, and in 14/25 pts after the VPT, but CRT deteriorated in 4 patients on this latter group, all of them receiving a concomitant low-dose vasopressin. CONCLUSIONS: Our findings support that fluid boluses may improve CRT or produce neutral effects in fluid-responsive septic shock patients with persistent hypoperfusion. Conversely, raising NE doses to target a higher MAP in previously hypertensive patients elicits a more heterogeneous response, improving CRT in the majority, but deteriorating skin perfusion in some patients, a fact that deserves further research.

Fluid Responsiveness Is Associated with Successful Weaning after Liver Transplant Surgery.

A positive fluid balance may evolve to fluid overload and associate with organ dysfunctions, weaning difficulties, and increased mortality in ICU patients. We explored whether individualized fluid management, assessing fluid responsiveness via a passive leg-raising maneuver (PLR) before a spontaneous breathing trial (SBT), is associated with less extubation failure in ventilated patients with a high fluid balance admitted to the ICU after liver transplantation (LT). We recruited 15 LT patients in 2023. Their postoperative fluid balance was +4476 {3697, 5722} mL. PLR maneuvers were conducted upon ICU admission (T1) and pre SBT (T2). Cardiac index (CI) changes were recorded before and after each SBT (T3). Seven patients were fluid-responsive at T1, and twelve were responsive at T2. No significant differences occurred in hemodynamic, respiratory, and perfusion parameters between the fluid-responsive and fluid-unresponsive patients at any time. Fluid-responsive patients at T1 and T2 increased their CI during SBT from 3.1 {2.8, 3.7} to 3.7 {3.4, 4.1} mL/min/m2 (p = 0.045). All fluid-responsive patients at T2 were extubated after the SBTs and consolidated extubation. Two out of three of the fluid-unresponsive patients experienced weaning difficulties. We concluded that fluid-responsive patients post LT may start weaning earlier and achieve successful extubation despite a high postoperative fluid balance. This highlights the profound impact of personalized assessments of cardiovascular state on critical surgical patients.

Consistency of data reporting in fluid responsiveness studies in the critically ill setting: the CODEFIRE consensus from the Cardiovascular Dynamic section of the European Society of Intensive Care Medicine.

PURPOSE: To provide consensus recommendations regarding hemodynamic data reporting in studies investigating fluid responsiveness and fluid challenge (FC) use in the intensive care unit (ICU). METHODS: The Executive Committee of the European Society of Intensive Care Medicine (ESICM) commissioned and supervised the project. A panel of 18 international experts and a methodologist identified main domains and items from a systematic literature, plus 2 ancillary domains. A three-step Delphi process based on an iterative approach was used to obtain the final consensus. In the Delphi 1 and 2, the items were selected with strong (≥ 80% of votes) or week agreement (70-80% of votes), while the Delphi 3 generated recommended (≥ 90% of votes) or suggested (80-90% of votes) items (RI and SI, respectively). RESULTS: We identified 5 main domains initially including 117 items and the consensus finally resulted in 52 recommendations or suggestions: 18 RIs and 2 SIs statements were obtained for the domain "ICU admission", 11 RIs and 1 SI for the domain "mechanical ventilation", 5 RIs for the domain "reason for giving a FC", 8 RIs for the domain pre- and post-FC "hemodynamic data", and 7 RIs for the domain "pre-FC infused drugs". We had no consensus on the use of echocardiography, strong agreement regarding the volume (4 ml/kg) and the reference variable (cardiac output), while weak on administration rate (within 10 min) of FC in this setting. CONCLUSION: This consensus found 5 main domains and provided 52 recommendations for data reporting in studies investigating fluid responsiveness in ICU patients.

Direct assessment of microcirculation in shock: a randomized-controlled multicenter study.

PURPOSE: Shock is a life-threatening condition characterized by substantial alterations in the microcirculation. This study tests the hypothesis that considering sublingual microcirculatory perfusion variables in the therapeutic management reduces 30-day mortality in patients admitted to the intensive care unit (ICU) with shock. METHODS: This randomized, prospective clinical multicenter trial-recruited patients with an arterial lactate value above two mmol/L, requiring vasopressors despite adequate fluid resuscitation, regardless of the cause of shock. All patients received sequential sublingual measurements using a sidestream-dark field (SDF) video microscope at admission to the intensive care unit (± 4 h) and 24 (± 4) hours later that was performed blindly to the treatment team. Patients were randomized to usual routine or to integrating sublingual microcirculatory perfusion variables in the therapy plan. The primary endpoint was 30-day mortality, secondary endpoints were length of stay on the ICU and the hospital, and 6-months mortality. RESULTS: Overall, we included 141 patients with cardiogenic (n = 77), post cardiac surgery (n = 27), or septic shock (n = 22). 69 patients were randomized to the intervention and 72 to routine care. No serious adverse events (SAEs) occurred. In the interventional group, significantly more patients received an adjustment (increase or decrease) in vasoactive drugs or fluids (66.7% vs. 41.8%, p = 0.009) within the next hour. Microcirculatory values 24 h after admission and 30-day mortality did not differ [crude: 32 (47.1%) patients versus 25 (34.7%), relative risk (RR) 1.39 (0.91-1.97); Cox-regression: hazard ratio (HR) 1.54 (95% confidence interval (CI) 0.90-2.66, p = 0.118)]. CONCLUSION: Integrating sublingual microcirculatory perfusion variables in the therapy plan resulted in treatment changes that do not improve survival at all.

Effective hemodynamic monitoring.

Hemodynamic monitoring is the centerpiece of patient monitoring in acute care settings. Its effectiveness in terms of improved patient outcomes is difficult to quantify. This review focused on effectiveness of monitoring-linked resuscitation strategies from: (1) process-specific monitoring that allows for non-specific prevention of new onset cardiovascular insufficiency (CVI) in perioperative care. Such goal-directed therapy is associated with decreased perioperative complications and length of stay in high-risk surgery patients. (2) Patient-specific personalized resuscitation approaches for CVI. These approaches including dynamic measures to define volume responsiveness and vasomotor tone, limiting less fluid administration and vasopressor duration, reduced length of care. (3) Hemodynamic monitoring to predict future CVI using machine learning approaches. These approaches presently focus on predicting hypotension. Future clinical trials assessing hemodynamic monitoring need to focus on process-specific monitoring based on modifying therapeutic interventions known to improve patient-centered outcomes.

Fluid challenge in critically ill patients receiving haemodynamic monitoring: a systematic review and comparison of two decades.

INTRODUCTION: Fluid challenges are widely adopted in critically ill patients to reverse haemodynamic instability. We reviewed the literature to appraise fluid challenge characteristics in intensive care unit (ICU) patients receiving haemodynamic monitoring and considered two decades: 2000-2010 and 2011-2021. METHODS: We assessed research studies and collected data regarding study setting, patient population, fluid challenge characteristics, and monitoring. MEDLINE, Embase, and Cochrane search engines were used. A fluid challenge was defined as an infusion of a definite quantity of fluid (expressed as a volume in mL or ml/kg) in a fixed time (expressed in minutes), whose outcome was defined as a change in predefined haemodynamic variables above a predetermined threshold. RESULTS: We included 124 studies, 32 (25.8%) published in 2000-2010 and 92 (74.2%) in 2011-2021, overall enrolling 6,086 patients, who presented sepsis/septic shock in 50.6% of cases. The fluid challenge usually consisted of 500 mL (76.6%) of crystalloids (56.6%) infused with a rate of 25 mL/min. Fluid responsiveness was usually defined by a cardiac output/index (CO/CI) increase ≥ 15% (70.9%). The infusion time was quicker (15 min vs 30 min), and crystalloids were more frequent in the 2011-2021 compared to the 2000-2010 period. CONCLUSIONS: In the literature, fluid challenges are usually performed by infusing 500 mL of crystalloids bolus in less than 20 min. A positive fluid challenge response, reported in 52% of ICU patients, is generally defined by a CO/CI increase ≥ 15%. Compared to the 2000-2010 decade, in 2011-2021 the infusion time of the fluid challenge was shorter, and crystalloids were more frequently used.

Pathophysiology, mechanisms, and managements of tissue hypoxia.

Oxygen is needed to generate aerobic adenosine triphosphate and energy that is required to support vital cellular functions. Oxygen delivery (DO2) to the tissues is determined by convective and diffusive processes. The ability of the body to adjust oxygen extraction (ERO2) in response to changes in DO2 is crucial to maintain constant tissue oxygen consumption (VO2). The capability to increase ERO2 is the result of the regulation of the circulation and the effects of the simultaneous activation of both central and local factors. The endothelium plays a crucial role in matching tissue oxygen supply to demand in situations of acute drop in tissue oxygenation. Tissue oxygenation is adequate when tissue oxygen demand is met. When DO2 is severely compromised, a critical DO2 value is reached below which VO2 falls and becomes dependent on DO2, resulting in tissue hypoxia. The different mechanisms of tissue hypoxia are circulatory, anaemic, and hypoxic, characterised by a diminished DO2 but preserved capacity of increasing ERO2. Cytopathic hypoxia is another mechanism of tissue hypoxia that is due to impairment in mitochondrial respiration that can be observed in septic conditions with normal overall DO2. Sepsis induces microcirculatory alterations with decreased functional capillary density, increased number of stopped-flow capillaries, and marked heterogeneity between the areas with large intercapillary distance, resulting in impairment of the tissue to extract oxygen and to satisfy the increased tissue oxygen demand, leading to the development of tissue hypoxia. Different therapeutic approaches exist to increase DO2 and improve microcirculation, such as fluid therapy, transfusion, vasopressors, inotropes, and vasodilators. However, the effects of these agents on microcirculation are quite variable.

Ressuscitação direcionada ao tempo de enchimento capilar baseada em fenótipo hemodinâmico no choque séptico precoce: protocolo de estudo do ensaio clínico randomizado ANDROMEDA-SHOCK-2 / Hemodynamic phenotype-based, capillary refill time-targeted resuscitation in early septic shock: The ANDROMEDA-SHOCK-2 Randomized Clinical Trial study protocol

RESUMO Introdução: A reversão precoce da hipoperfusão tecidual induzida é essencial para a sobrevida no choque séptico. No entanto, falta consenso sobre a melhor estratégia de ressuscitação inicial, uma vez que intervenções destinadas a toda a população com choque séptico podem produzir administração desnecessária de líquidos. Este artigo relata a justificativa, o delineamento e o plano de análise do estudo ANDROMEDA-2, que visa determinar se uma estratégia guiada por perfusão periférica, que consiste na ressuscitação guiada pelo tempo de enchimento capilar com base em fenótipos clínicos e hemodinâmicos, está associada a uma diminuição no desfecho composto de mortalidade, tempo até a interrupção ao suporte de órgãos e tempo de internação em comparação com o atendimento padrão em pacientes com choque séptico precoce (< 4 horas do diagnóstico). Metódos: O estudo ANDROMEDA-2 é um ensaio clínico randomizado controlado multinacional e multicêntrico. No grupo de intervenção, o tempo de enchimento capilar será medido a cada hora, durante 6 horas. Se estiver anormal, os pacientes serão alocados em um algoritmo, começando com a avaliação da pressão de pulso. Pacientes com pressão de pulso inferior a 40mmHg serão testados quanto à capacidade de resposta a líquidos e receberão líquidos de acordo. Em pacientes com pressão de pulso > 40mmHg, norepinefrina será titulada para manter a pressão arterial diastólica > 50mmHg. Os pacientes que não normalizarem o tempo de enchimento capilar após as etapas anteriores serão submetidos à ecocardiografia de cuidados intensivos para avaliação da disfunção cardíaca e posterior manejo. Por fim, serão realizados testes com vasopressores e inodilatadores para otimizar ainda mais a perfusão. Um tamanho de amostra de 1.500 pacientes fornecerá 88% de poder para demonstrar a superioridade da estratégia direcionada ao tempo de enchimento capilar. Conclusão: Se for demonstrado que o direcionamento ao tempo de enchimento capilar é uma estratégia melhor, os processos de atendimento na ressuscitação do choque séptico podem ser otimizados com ferramentas usadas à beira do leito.

ABSTRACT Background: Early reversion of sepsis-induced tissue hypoperfusion is essential for survival in septic shock. However, consensus regarding the best initial resuscitation strategy is lacking given that interventions designed for the entire population with septic shock might produce unnecessary fluid administration. This article reports the rationale, study design and analysis plan of the ANDROMEDA-2 study, which aims to determine whether a peripheral perfusion-guided strategy consisting of capillary refill time-targeted resuscitation based on clinical and hemodynamic phenotypes is associated with a decrease in a composite outcome of mortality, time to organ support cessation, and hospital length of stay compared to standard care in patients with early (< 4 hours of diagnosis) septic shock. Methods: The ANDROMEDA-2 study is a multicenter, multinational randomized controlled trial. In the intervention group, capillary refill time will be measured hourly for 6 hours. If abnormal, patients will enter an algorithm starting with pulse pressure assessment. Patients with pulse pressure less than 40mmHg will be tested for fluid responsiveness and receive fluids accordingly. In patients with pulse pressure > 40mmHg, norepinephrine will be titrated to maintain diastolic arterial pressure > 50mmHg. Patients who fail to normalize capillary refill time after the previous steps will be subjected to critical care echocardiography for cardiac dysfunction evaluation and subsequent management. Finally, vasopressor and inodilator tests will be performed to further optimize perfusion. A sample size of 1,500 patients will provide 88% power to demonstrate superiority of the capillary refill time-targeted strategy. Conclusions: If hemodynamic phenotype-based, capillary refill time-targeted resuscitation demonstrates to be a superior strategy, care processes in septic shock resuscitation can be optimized with bedside tools.

Global greenhouse gas emissions from residential and commercial building materials and mitigation strategies to 2060.

Building stock growth around the world drives extensive material consumption and environmental impacts. Future impacts will be dependent on the level and rate of socioeconomic development, along with material use and supply strategies. Here we evaluate material-related greenhouse gas (GHG) emissions for residential and commercial buildings along with their reduction potentials in 26 global regions by 2060. For a middle-of-the-road baseline scenario, building material-related emissions see an increase of 3.5 to 4.6 Gt CO2eq yr-1 between 2020-2060. Low- and lower-middle-income regions see rapid emission increase from 750 Mt (22% globally) in 2020 and 2.4 Gt (51%) in 2060, while higher-income regions shrink in both absolute and relative terms. Implementing several material efficiency strategies together in a High Efficiency (HE) scenario could almost half the baseline emissions. Yet, even in this scenario, the building material sector would require double its current proportional share of emissions to meet a 1.5 °C-compatible target.

Plano de análise estatística para o estudo do tratamento precoce baseado em metas com utilização de uma visão fisiológica holística - estudo ANDROMEDA-SHOCK: um estudo randomizado e controlado / Statistical analysis plan for early goal-directed therapy using a physiological holistic view - the ANDROMEDA-SHOCK: a randomized controlled trial

RESUMO Fundamentação: O estudo ANDROMEDA-SHOCK é um estudo internacional, multicêntrico, randomizado e controlado comparando ressuscitação guiada pela perfusão periférica com ressuscitação guiada pelo lactato em pacientes com choque séptico, com a finalidade de testar a hipótese de que a ressuscitação guiada pela perfusão periférica associa-se a menor morbidade e mortalidade. Objetivo: Relatar o plano de análise estatística para o estudo ANDROMEDA-SHOCK. Métodos: Descrevemos o delineamento do estudo, os objetivos primário e secundários, pacientes, métodos de randomização, intervenções, desfechos e tamanho da amostra. Descrevemos nossos planos de análise estatística para os desfechos primários, secundários e terciários. Também descrevemos as análises de subgrupos e sensibilidade. Finalmente, fornecemos detalhes para a apresentação dos resultados, inclusive modelos de tabelas para apresentar as características basais, a evolução das variáveis de hemodinâmica e perfusão, e os efeitos dos tratamentos nos desfechos. Conclusão: Segundo as melhores práticas de pesquisa, relatamos nosso plano de análise estatística e plano de gestão de dados antes do fechamento da base de dados e do início da análise dos dados. Nossa expectativa é que este procedimento previna a ocorrência de vieses na análise e incremente a utilidade dos resultados relatados.

ABSTRACT Background: ANDROMEDA-SHOCK is an international, multicenter, randomized controlled trial comparing peripheral perfusion-targeted resuscitation to lactate-targeted resuscitation in patients with septic shock in order to test the hypothesis that resuscitation targeting peripheral perfusion will be associated with lower morbidity and mortality. Objective: To report the statistical analysis plan for the ANDROMEDA-SHOCK trial. Methods: We describe the trial design, primary and secondary objectives, patients, methods of randomization, interventions, outcomes, and sample size. We describe our planned statistical analysis for the primary, secondary and tertiary outcomes. We also describe the subgroup and sensitivity analyses. Finally, we provide details for presenting our results, including mock tables showing baseline characteristics, the evolution of hemodynamic and perfusion variables, and the effects of treatments on outcomes. Conclusion: According to the best trial practice, we report our statistical analysis plan and data management plan prior to locking the database and initiating the analyses. We anticipate that this procedure will prevent analysis bias and enhance the utility of the reported results.

Evaluación de la microcirculación con sidestream dark field (SDF) Microscan® como método de monitorización en microcirugía en modelo porcino / Microcirculation assessment with sidestream dark field (SDF) Microscan® as flap monitoring method in microsurgery in a porcine model

Objetivo: Determinar la factibilidad de la monitorización en microcirugía por medio de la evaluación no invasiva de la microcirculación con sidestream dark field (SDF) y compararla con otros métodos. Materiales y métodos: Estudio experimental. En 8 cerdos se elevó colgajo pectoral y se disecó pedículo. Se llevó a cabo una instalación sucesiva de dispositivos cutáneos para la evaluación de la microcirculación: SDF para evaluar flujo, y near infrared spectroscopy (NIRS) para evaluar saturación de O2 (SatO2). Posteriormente se evaluó la oclusión venosa, arterial y total con pinzamiento durante 180 s. Resultados: SDF en oclusión venosa: disminución del flujo: 51 s (59-62); SDF en oclusión arterial: disminución del flujo: 3 s (1-5); SDF en oclusión vascular total: disminución del flujo: 3,5 s (2-5). NIRS en oclusión venosa: disminución de la SatO2:15,2 ± 5,3%; NIRS en oclusión arterial: disminución de la SatO2 23,9 ± 13,8%; NIRS en oclusión vascular total: disminución de la SatO2 23,85 ± 13,9%. Doppler en oclusión venosa: no desapareció; Doppler en oclusión arterial y oclusión vascular total: desapareció a los 2 s. En cada una de las mediciones, los cambios clínicos fueron más tardíos que los observados con SDF. Conclusión: Es factible la monitorización en microcirugía por medio de la evaluación de la microcirculación con Microscan®. Este método permite realizar el diagnóstico de oclusión vascular más tempranamente que con NIRS y evaluación clínica.

Aim: Determine the feasibility of using SDF Microscan® as a non-invasive method for monitoring free flap microcirculation, and compare it to other methods. Materials and methods: Experimental study. In 8 pigs a pectoral myocutaneous flap was raised. Microcirculation was evaluated using: SDF Microscan®, near infrared spectroscopy (NIRS), clinical examination and Doppler. Venous, arterial and total occlusion was performed by clamping the vascular pedicle. Mean time to blood flow impairment diagnosis was measured. Results: SDF in venous occlusion: reduced microcirculatory flow index at: 51 s (59-62). SDF in arterial occlusion: reduced microcirculatory flow index at: 3 s (1-5). SDF in total vascular occlusion: reduced microcirculatory flow index at: 3.5 s (2-5). NIRS in venous occlusion: SatO2 decrease was 15.2 ± 5.3%. NIRS in arterial occlusion: SatO2 decrease was 23.9 ± 13.8%. NIRS in total vascular occlusion: SatO2 decrease was 23.85 ± 13.9%. Doppler in venous occlusion: The signal did not disappear. Doppler arterial and total vascular occlusion disappears at 2 s. The clinical changes were later than SDF. Conclusion: Microcirculation monitoring is feasible using SDF Microscan® in a pig model. This method allows to detect blood flow disruption earlier than NIRS and clinical evaluation.

Mini-report: Microcirculatory flow abnormalities in a patient with severe hyperviscosity syndrome.

A 60-year women was admitted to ICU because seizures, poor peripheral perfusion and acute renal failure. In laboratory tests an hyperproteinemia was detected, and therefore an electrophoresis and a bone marrow biopsy were performed, confirming a Waldenström Macroglobulinemia with severe hyperviscosity. Sublingual microcirculation was assessed with videomicroscopy, finding sluggish and intermittent microvascular flow, despite normal lactate and mixed venous O2 saturation. Promptly plasmapheresis was started, with viscosity decrease in parallel with improvement in microvascular flow and clinical status. Three days after the first plasmapheresis the patient was discharged from ICU. This case shows the critical role of viscosity on microcirculatory flow.

Pressão expiratória final positiva aumenta o estiramento em pacientes com LPA/SDRA / Positive end-expiratory pressure increases strain in patients with ALI/ARDS

OBJETIVO: O objetivo deste estudo foi avaliar os efeitos da pressão expiratória final positiva no estiramento, recrutamento e recrutamento e desrecrutamento cíclico avaliados por tomografia computadorizada pulmonar em pacientes com lesão pulmonar aguda/síndrome do desconforto respiratório agudo. MÉTODOS: Trata-se de um estudo aberto, controlado, não randomizado, de intervenção, em pacientes com lesão pulmonar aguda/síndrome do desconforto respiratório agudo. Foram realizados cortes simples de tomografia computadorizada durante pausas inspiratórias e expiratórias com um volume corrente de 6 ml/kg e níveis de pressão expiratória final positiva de 5, 10, 15 e 20 cmH2O. Medimos as densidades do parênquima pulmonar em unidades Hounsfield e calculamos o recrutamento, recrutamento e desrecrutamento cíclico induzidos pela pressão expiratória final positiva, assim como o estiramento. RESULTADOS: O aumento dos níveis de pressão expiratória final positiva aumenta de forma consistente o recrutamento e o estiramento globais (p<0,01), o que se correlacionou de forma significante com a pressão de platô (r²=0,97; p<0,01). O aumento dos níveis de pressão expiratória final positiva aumentou sistematicamente a distensão alveolar em todo o eixo esternovertebral. CONCLUSÃO: A distensão alveolar é um efeito adverso da pressão expiratória final positiva que deve ser ponderado em qualquer paciente em relação ao seus potenciais benefícios no recrutamento. Em razão do número reduzido de pacientes, estes dados devem ser considerados como geradores de hipótese e não limitar a aplicação de valores elevados de pressão expiratória final positiva em pacientes com hipoxemia grave.

OBJECTIVE: The objective of this study was to assess the effects of positive end-expiratory pressure on recruitment, cyclic recruitment and derecruitment and strain in patients with acute lung injury and acute respiratory distress syndrome using lung computed tomography. METHODS: This is an open, controlled, non-randomized interventional study of ten patients with acute lung injury and acute respiratory distress syndrome. Using computed tomography, single, basal slices of the lung were obtained during inspiratory and expiratory pauses at a tidal volume of 6 ml/kg and a positive end-expiratory pressure of 5, 10, 15 and 20 cmH2O. The densities of the lung parenchyma were measured in Hounsfield units. The values for positive end-expiratory pressure-induced recruitment, cyclic recruitment and derecruitment and strain were then calculated. RESULTS: Increasing levels of positive end-expiratory pressure were correlated with increased recruitment and global strain (p < 0.01), which was significantly correlated with plateau pressure (r² = 0.97, p < 0.01). In addition, increasing levels of positive end-expiratory pressure systematically increased strain along the sternovertebral axis. CONCLUSION: While strain is an adverse effect of positive end-expiratory pressure, the decision use positive end-expiratory pressure with any patient should be balanced against the potential benefits of recruitment. Due to the small number of patients in this study, the present data should be treated as hypothesis generating and is not intended to limit the clinical application of a high level of positive end-expiratory pressure in patients with severe hypoxemia.

Intraabdominal hypertension in patients with septic shock.

Intraabdominal hypertension (IAH) develops frequently in patients with septic shock. Even a moderate increase in intraabdominal pressure (IAP) in this setting could be associated with high lactate levels. The authors conducted a prospective, observational, nonrandomized control trial in the surgical intensive care unit of an academic tertiary center. Twenty-seven patients with septic shock (septic shock group), and 19 patients undergoing abdominal surgery with more than two risk factors for IAH (postoperative control group) were admitted consecutively to the intensive care unit. IAP was measured every 6 hours during the first 48 hours. IAH was diagnosed with two consecutive measurements greater than 20 mm Hg. The main outcome measures were prevalence of IAH in septic shock and control groups; and comparative lactate levels, norepinephrine requirements and organ dysfunctions in patients with and without IAH in both groups. Fifty-one per cent of patients with septic shock and 31 per cent of control patients developed IAH. Patients with septic shock with and without IAH were comparable in peak norepinephrine dose, sequential organ failure assessment score, and mortality. However, peak lactate levels were significantly higher in patients with septic shock and IAH compared with those without IAH (3.5 mmol/L versus 1.9 mmol/L, P < 0.04). There was a significant positive temporal correlation between IAP and lactate levels in patients with septic shock with IAH. Peak levels of both occurred early and decreased progressively over time. Control patients with and without IAH exhibited comparable peak lactate levels. Intraabdominal hypertension is very common in septic shock and appears to be related to high lactate levels, which diminish as IAP decreases. Future studies should address the usefulness of IAP monitoring in patients with septic shock.

Biodisponibilidad del fósforo de cereales en aves / Cereal Phosphorus Bio-Availability in Chicks

En aves en crecimiento, se determinó la biodisponibilidad del fósforo del trigo, maíz y sorgo, mediante el método de relación de las pendientes de dietas referenciales con niveles crecientes de fósforo inorgánico y las de los cereales. Se utilizó como variable independiente el consumo de fósforo, para las dietas de referencia, y consumo de alimento, para las dietas con trigo, maíz o sorgo, y como variable dependiente el contenido de cenizas de la tibia de pollos de cuatro semanas de edad. El peso (g) y el contenido de cenizas (%) del hueso fueron superiores (P < 0,05) para el trigo (1020; 43,6), intermedios para el maìz (823; 30,44) y más bajos para el sorgo (655; 28,97). La ganancia de peso y contenido de cenizas se incrementó (P < 0,05) por cada aumento del nivel de fósforo inorgánico (0,25; 0,35; 0,45%) de las dietas de referencia. Las regresiones y correlaciones entre las variables de consumo y contenido de cenizas del hueso fueron significativas (P < 0,05) para los cereales y dietas referenciales. La relación entre las pendientes de las regresiones permitió estimar la biodisponibildad del fósforo del trigo, maíz y sorgo en 26,66; 24,67 y 23,0%, respectivamente.

In growing chicks, phosphorus bioavailability of wheat, corn and sorghum grains was determined by the slope relation between the regression equations of reference diets, with increasing levels of inorganic phosphorus, and those of the cereals. Phosphorus intake was used as independent variable, for references diets, and feed intake, for wheat, corn or sorghum diets, and tibia bone ash of 4 week old chicks as dependent variable. Weight (g) and bone ash (%) content were higher (P < 0.05) for wheat (1020; 43.6), intermediate for corn (823; 30.44) and lower for sorghum (655; 28.97). Body weight (g) gain and bone ash (%) were greater (P < 0.05) for each increasing levels of inorganic phosphorus (0.25, 0.35, 0.45%) of the reference diets. Regressions and correlations between phosphorus intake and bone ash were significant (P < 0.05) for cereal and reference diets. According the slope relation of the regression equations, phosphorus bioavailability values of wheat, corn and sorghum were 26.66, 24.67 and 23.0% respectively.

Desarrollo de un modelo experimental de hipertensión intra-abdominal / Development of an experimental model of intra-abdominal hypertension

Objetivos: Desarrollar un modelo porcino experimental de hipertensión intra-abdominal. Estudiar los efectos de la hipertensión intra-abdominal sobre la macro-hemodinamia, parámetros ventilatorios y perfusión esplácnica. Métodos: Se sometió a anestesia y ventilación mecánica a un grupo de 5 cerdos machos. Se realizó monitorización hemodinámica invasiva. Se sometió a los animales a una laparotomía para cateterizar la vena porta e instalar un tonómetro intrayeyunal, y se elevó la presión intra-abdominal a 15 mmHg infundiendo manitol 7,5 por ciento a la cavidad abdominal. Una hora después se volvieron a realizar mediciones y posteriormente se realizaron incrementos sucesivos de la presión intra-abdominal a niveles de 25 y 35 mmHg. Resultados: La hipertensión intra-abdominal produjo una disminución del gasto cardíaco (p <0,001) con aumento de la presión venosa central (p <0,001) y la presión de oclusión en la arteria pulmonar (p=0,073). Existió un incremento significativo en las presiones pico y meseta de la vía aérea, asociado a una reducción de la distensibilidad toraco-pulmonar (p <0,001). De los parámetros de perfusión regional el pH intramucoso fue el más precoz y sensible en detectar hipoperfusión esplácnica(p=0,04). El lactato arterial y venoso portal no tuvieron una buena correlación con el aumento de la presión intra-abdominal(p=NS). Conclusiones: El modelo presenta cambios hemodinámicos, ventilatorios y de perfusión esplácnica reproducibles que son concordantes con los observados en el SCA y constituye un instrumento valioso para futuros estudios de intervención terapéutica.

Peep intrínseco (PEEPi) en dos estrategias ventilatorias: volumen corriente tradicional versus volumen corriente bajo y frecuencia respiratoria alta / Intrinsic Peep (PEEPi)in two ventilator strategies: traditional tidal volume versus low tidal volume and high respiratory frequency

La ventilación con volumen corriente (Vt) de 6 ml/kg disminuyó en más de 20 por ciento la mortalidad del SDRA versus el uso de Vt de 12 ml/kg (ARDSnetwork). el uso de frecuencias respiratorias cercanas a 30 por minuto, en el grupo con Vt pequeño, pudiera generar la presencia de autoPEEP o PEEP intrínseco (PEEPi). Quisimos evaluar el nivel de PEEPi en pacientes con SDRA en su fase aguda en las dos condiciones de ventilación del estudio del ARDSnetwork.Estudiamos ocho pacientes con un SDRA en su fase precoz, que fueron ventilados en las dos modalidades en forma secuencial: a) estrategia protectora, Vt 6,2 ml/kg; FR 29; PEEP externo 9,4 cmH2O; b) estrategia convencional, Vt 11,8 ml/kg; FR 16; PEEP externo 8,6 cmH2O. Después de 15 minutos, el PEEP total se midió mediante una pausa espiatoria de 5 segundos. Se definió el PEEPi como el PEEP total menos el PEEP externo.

Valor pronóstico de la proteína C reactiva en pacientes sometidos a ventilación mecánica / Predictive value of C-reactive protein in patients receiving mechanical ventilation

La Proteína C Reactiva (PCR) es una de las proteínas de fase aguda más utilizadas en clínica, como marcador de infección y de intensidad de la respuesta inflamatoria. En el presente estudio evaluamos la utilidad clínica de la PCR en pacientes críticos sometidos a ventilación mecánica (VM). De 214 pacientes admitidos a la UCI Quirúrgica desde junio de 1999 a diciembre del 2000 y que fueron ventilados por más de 24 horas, 160 (75 por ciento) tenían medición de PCR. El 73 por ciento de ellos ingresó por problemas infecciosos, mientras el 27 por ciento lo hizo por problemas neurológicos. No hubo diferencia entre la PCR de ingreso o PCR máxima de los pacientes que sobrevivieron y los que fallecieron. Tampoco hubo correlación entre el valor de la PCR y los días de UCI, días de VM y días libres de VM. La mortalidad de 131 pacientes que alcanzaron la PCR máxima antes de las primeras 72 horas de admisión a la UCI fue inferior a aquellos que la presentaron después de las 72 horas (17,6 por ciento vs 44,8 por ciento, p<0,05). En el presente estudio, la PCR como valor aislado no mostró gran valor pronóstico en cuanto a la sobrevida de los pacientes, ni a los días en UCI o en VM. Sin embargo, su evolución en el tiempo aporta información clínica que puede ser relevante en el manejo de los pacientes ventilados.