Kuo-Chin Kao

Prediction of fluid responsiveness in acute respiratory distress syndrome patients ventilated with low tidal volume and high positive end-expiratory pressure*

Objective:Dynamic preload indicators with pulse pressure variation and stroke volume variation are superior to static indicators for predicting fluid responsiveness in mechanically ventilated patients. However, they are influenced by tidal volume and the level of positive end-expiratory pressure. The present study was designed to evaluate the clinical applicability of pulse pressure variation and stroke volume variation in predicting fluid responsiveness on acute respiratory distress syndrome patients ventilated with protective strategy (low tidal volume and high positive end-expiratory pressure). Design:Prospective, observational study. Setting:A 20-bed medical intensive care unit of a tertiary medical center. Patients:Twenty-two sedated and paralyzed early acute respiratory distress syndrome patients. Interventions:After being enrolled, central venous pressure, pulmonary capillary wedge pressure, and cardiac output index were obtained from a pulmonary artery catheter (OptiQ SvO2/CCO catheter), and intrathoracic blood volume, global end-diastolic volume, stroke volume variation, and pulse pressure variation were recorded from a PiCCOplus monitor. The whole set of hemodynamic measurements was performed before and after volume expansion with 500 mL hydroxyethyl starch (10% pentastarch 200/0.5). Measurements and Main Results:Cardiac output index, central venous pressure, pulmonary capillary wedge pressure, global end-diastolic volume, and intrathoracic blood volume significantly increased, and pulse pressure variation and stroke volume variation significantly decreased after volume expansion. Baseline pulse pressure variation significantly correlated with volume expansion-induced absolute changes (r = .62), or percent changes in cardiac output index (r = .75) after volume expansion. The area under the receiver operating characteristic curve was the highest for pulse pressure variation (area under the receiver operating characteristic curve = 0.768) than other indicators. The threshold value for baseline pulse pressure variation greater than 11.8% predicted a significant positive response to volume expansion with a sensitivity of 68% and a specificity of 100%. Conclusions:Baseline pulse pressure variation accurately predicted the fluid responsiveness in early acute respiratory distress syndrome patients. Roughly, a baseline pulse pressure variation greater than the threshold value of 12% is associated with a significant increase in cardiac output index after the end of volume expansion.

Open lung biopsy in early-stage acute respiratory distress syndrome.

IntroductionAcute respiratory distress syndrome (ARDS) has heterogeneous etiologies, rapid progressive change and a high mortality rate. To improve the outcome of ARDS, accurate diagnosis is essential to the application of effective early treatment. The present study investigated the clinical effects and safety of open lung biopsy (OLB) in patients with early-stage ARDS of suspected non-infectious origin.MethodsWe undertook a retrospective study of 41 patients with early-stage ARDS (defined as one week or less after intubation) who underwent OLB in two medical intensive care units of a tertiary care hospital from 1999 to 2005. Data analyzed included baseline characteristics, complication rate, pathological diagnoses, treatment alterations, and hospital survival.ResultsThe age of patients was 55 ± 17 years (mean ± SD). The average ratio of arterial partial pressure of oxygen (PaO2) to fraction of inspired oxygen (FiO2) was 116 ± 43 mmHg (mean ± SD) at biopsy. Seventeen patients (41%) were immunocompromised. Postoperative complications occurred in 20% of patients (8/41). All biopsies provided a pathological diagnosis with a diagnostic yield of 100%. Specific pathological diagnoses were made for 44% of patients (18/41). Biopsy findings led to an alteration of treatment modality in 73% of patients (30/41). The treatment alteration rate was higher in patients with nonspecific diagnoses than in patients with specific diagnoses (p = 0.0024). Overall mortality was 50% (21/41) and was not influenced by age, gender, pre-OLB oxygenation, complication rate, pathological results, and alteration of treatment. There was no surgery-related mortality. The survival rate for immunocompromised patients was better than that for immunocompetent patients (71% versus 33%; p = 0.0187) in this study.ConclusionOur retrospective study suggests that OLB was a useful and acceptably safe diagnostic procedure in some selected patients with early-stage ARDS.

Risk factors for nosocomial infection during extracorporeal membrane oxygenation

An increasing number of patients receive extracorporeal membrane oxygenation (ECMO) for life support. This study aimed to investigate the incidence and risk factors for nosocomial infection in adult patients receiving ECMO. We reviewed the medical records of adult patients who received ECMO support for more than 72h at Far Eastern Memorial Hospital from 2001 to 2007. ECMO-related nosocomial infections were defined as infections occurring from 24h after ECMO initiation until 48h after ECMO discontinuation. There were 12 episodes of nosocomial infection identified in 10 of the 114 (8.77%) patients on ECMO, including four cases of pneumonia, three cases of bacteraemia, three surgical site infections and two urinary tract infections. The incidence of ECMO-related nosocomial infection was 11.92 per 1000 ECMO-days. The length of ECMO use and intensive care unit (ICU) stay were significantly different between patients with, and without, nosocomial infection (P<0.001). More than 10 days of ECMO use was associated with a significantly higher nosocomial infection rate (P=0.003). Gram-negative bacilli were responsible for 78% of the nosocomial infections. In the univariate analysis, the duration of ICU stay and duration of ECMO use were associated with nosocomial infection. In the multivariate analysis, only the duration of ECMO was independently associated with nosocomial infection (P=0.007). Overall, the only independent risk factor for ECMO-related nosocomial infection identified in this study was prolonged ECMO use.

Predictors of successful weaning from prolonged mechanical ventilation in Taiwan.

BACKGROUND For adult patients on prolonged mechanical ventilation (PMV, >/=21 days), successful weaning has been attributed to various factors. The purpose of this study was to describe patient outcomes, weaning rates and factors in successful weaning at a hospital-based respiratory care center (RCC) in Taiwan. METHODS AND RESULTS This was a retrospective observational study performed in a 24-bed RCC over six years. A total of 1307 patients on PMV were included in the study. The overall survival rate was 62%. Fifty-six percent of patients were successfully weaned. Unsuccessfully weaned patients had higher MICU transfer rates, higher Acute Physiology and Chronic Health Evaluation II scores, longer duration of RCC stay, higher rates of being bed-ridden prior to admission, increased hemodialysis rates, higher modified Glasgow Coma Scale scores, higher rapid shallow breathing index, lower inspiratory pressure at residual volume (PImax) and lower blood urea nitrogen (BUN) and creatinine levels. Factors found to be associated with unsuccessful weaning were length of RCC stay (OR=1.04, P<0.001), modified GCS score (OR=0.93, P<0.046), PImax (OR=0.97, P<0.001), serum albumin concentration (OR=0.62, P<0.023) and BUN level (OR=1.01, P<0.002). CONCLUSION High rates of ventilator independence can be achieved in an RCC setting as an alternative to ICU care. Factors associated with unsuccessful weaning included longer duration of RCC stay, elevated BUN levels and lower modified GCS scores, serum albumin and PImax levels.

Diffuse alveolar damage associated mortality in selected acute respiratory distress syndrome patients with open lung biopsy

IntroductionDiffuse alveolar damage (DAD) is the pathological hallmark of acute respiratory distress syndrome (ARDS), however, the presence of DAD in the clinical criteria of ARDS patients by Berlin definition is little known. This study is designed to investigate the role of DAD in ARDS patients who underwent open lung biopsy.MethodsWe retrospectively reviewed all ARDS patients who met the Berlin definition and underwent open lung biopsy from January 1999 to January 2014 in a referred medical center. DAD is characterized by hyaline membrane formation, lung edema, inflammation, hemorrhage and alveolar epithelial cell injury. Clinical data including baseline characteristics, severity of ARDS, clinical and pathological diagnoses, and survival outcomes were analyzed.ResultsA total of 1838 patients with ARDS were identified and open lung biopsies were performed on 101 patients (5.5 %) during the study period. Of these 101 patients, the severity of ARDS on diagnosis was mild of 16.8 %, moderate of 56.5 % and severe of 26.7 %. The hospital mortality rate was not significant difference between the three groups (64.7 % vs 61.4 % vs 55.6 %, p = 0.81). Of the 101 clinical ARDS patients with open lung biopsies, 56.4 % (57/101) patients had DAD according to biopsy results. The proportion of DAD were 76.5 % (13/17) in mild, 56.1 % (32/57) in moderate and 44.4 % (12/27) in severe ARDS and there is no significant difference between the three groups (p = 0.113). Pathological findings of DAD patients had a higher hospital mortality rate than non-DAD patients (71.9 % vs 45.5 %, p = 0.007). Pathological findings of DAD (odds ratio: 3.554, 95 % CI, 1.385–9.12; p = 0.008) and Sequential Organ Failure Assessment score on the biopsy day (odds ratio: 1.424, 95 % CI, 1.187–1.707; p<0.001) were significantly and independently associated with hospital mortality. The baseline demographics and clinical characteristics were not significantly different between DAD and non-DAD patients.ConclusionsThe correlation of pathological findings of DAD and ARDS diagnosed by Berlin definition is modest. A pathological finding of DAD in ARDS patients is associated with hospital mortality and there are no clinical characteristics that could identify DAD patients before open lung biopsy.

OUTCOME SCORING SYSTEMS FOR ACUTE RESPIRATORY DISTRESS SYNDROME

Acute respiratory distress syndrome (ARDS) is commonly diagnosed in intensive care units (ICUs), often in association with acute kidney injury. In this study, we compared the predictive value of outcome scoring systems: Acute Physiology and Chronic Health Evaluation IV (APACHE IV), earlier APACHE models, Sequential Organ Failure Assessment (SOFA), the Risk of renal failure, Injury to the kidney, Failure of kidney function, Loss of kidney function, and End-stage renal failure (RIFLE) classification, and Acute Lung Injury score in critically ill patients with ARDS. We retrospectively abstracted data from the medical records of 135 critically ill ARDS patients in two medical ICUs of a tertiary care hospital from December 1999 to June 2006. Overall mortality rate was 65% (88/135). Forward conditional logistic regression identified APACHE IV, alveolar-arterial O2 tension difference, age, sepsis, and maximum RIFLE (RIFLEmax) score on ICU days 1 and 3 to be independent predictors of hospital mortality. The area under the receiver operating characteristic curve for the APACHE IV score revealed good fit (Hosmer and Lemeshow goodness-of-fit test results) and discriminative power (area under the receiver operating characteristic curve, 0.792 ± 0.038; P < 0.001). The cumulative survival rates at 6-month follow-up after hospital discharge were significantly (P < 0.001) different among ARDS patients with APACHE IV mortality rate 35% or less and APACHE IV mortality rate higher than 35%. The APACHE IV score and RIFLEmax score are predictors of hospital mortality in ARDS patients, with APACHE IV demonstrating desirable properties of prognostic accuracy.

Effects of Exercise Training on Pulmonary Mechanics and Functional Status in Patients With Prolonged Mechanical Ventilation

BACKGROUND: The functional status and outcomes in patients with prolonged mechanical ventilation (PMV) are often limited by poor endurance and pulmonary mechanics, which result from the primary diseases or prolonged time bedridden. We evaluate the impact of exercise training on pulmonary mechanics, physical functional status, and hospitalization outcomes in PMV patients. METHODS: Twenty-seven subjects with PMV in our respiratory care center (RCC) were divided randomly into an exercise training group (n = 12) and a control group (n = 15). The exercise program comprised 10 sessions of exercise training. The measurement of pulmonary mechanics and physical functional status (Functional Independence Measurement and Barthel index) were performed pre-study and post-study. The hospitalization outcomes included: days of mechanical ventilation, hospitalization days, and weaning and mortality rates during RCC stay. RESULTS: The training group had significant improvement in tidal volume (143.6 mL vs 192.5 mL, P = .02) and rapid shallow breathing index after training (162.2 vs 110.6, P = .009). No significant change was found in the control group except respiratory rate. Both groups had significant improvement in functional status during the study. However, the training group had greater changes in FIM score than the control group (44.6 vs 34.2, P = .024). The training group also had shorter RCC stay and higher weaning and survival rates than the control group, although no statistical difference was found. CONCLUSIONS: Subjects with PMV in our RCC demonstrated significant improvement in pulmonary mechanics and functional status after exercise training. The application of exercise training may be helpful for PMV patients to improve hospitalization outcomes.

Hypokalemic Muscular Paralysis Causing Acute Respiratory Failure Due to Rhabdomyolysis with Renal Tubular Acidosis in a Chronic Glue Sniffer

Case Report: A 34-year-old male was admitted to the emergency department with the development of quadriparesis and respiratory failure due to hypokalemia after prolonged glue sniffing. The patient was subsequently given mechanical ventilatory support for respiratory failure. He was weaned from the ventilator 4 days later after potassium replacement. Toluene is an aromatic hydrocarbon found in glues, cements, and solvents. It is known to be toxic to the nervous system, hematopoietic system, and causes acid-base and electrolyte disorders. Acute respiratory failure with hypokalemia and rhabdomyolysis with acute renal failure should be considered as potential events in a protracted glue sniffing.

Survival Predictors in Acute Respiratory Distress Syndrome With Extracorporeal Membrane Oxygenation

BACKGROUND Extracorporeal membrane oxygenation (ECMO) can be used as a salvage therapy, but the effectiveness is controversial. The aim of this study was to investigate the predictors of mortality and the influence of organ dysfunction scores in severe acute respiratory distress syndrome (ARDS) patients treated with ECMO. METHODS The records of adult severe ARDS patients receiving ECMO support from May 2006 to December 2011 at Chang Gung Memorial Hospital were retrospectively analyzed. RESULTS The records of 65 patients with severe ARDS who received venovenous ECMO were analyzed. The hospital survival rate was 47.7%. Survivors were younger than nonsurvivors (41.4 ± 15.4 versus 54.1 ± 16.9 years, respectively; p = 0.002) and had shorter duration of mechanical ventilation before ECMO (52.7 ± 51.1 versus 112.1 ± 101.0 hours, respectively; p = 0.01). Before ECMO, Acute Physiology and Chronic Health Evaluation II, Sequential Organ Failure Assessment, and Multiple Organ Dysfunction scores were significantly lower for survivors than for nonsurvivors. Mortality rate increased with rising predictive score. During 7 days of ECMO use, organ dysfunction scores were significantly lower for survivors than nonsurvivors. CONCLUSIONS Severe ARDS patients who are younger, have shorter duration of mechanical ventilation, and lower organ dysfunction scores before ECMO initiation have more favorable survival outcome. Early application of ECMO, especially if predictive score is below 2, may improve survival. Organ dysfunction scores before and during ECMO support are correlated with survival.

Effects of hydroxyethyl starch resuscitation on extravascular lung water and pulmonary permeability in sepsis-related acute respiratory distress syndrome.

Objective:Hydroxyethyl starch (HES) has greater volume expansion effect and longer intravascular persistence than crystalloids. HES also decreases microvascular permeability and capillary leakage by biophysically plugging endothelial leaks, exerting an anti-inflammatory effect, and decreasing activation of endothelial cells. The aim of our study was to determine whether medium molecular weight HES (pentastarch) resuscitation in the early stage of acute respiratory distress syndrome (ARDS) simultaneously increases cardiac output without worsening pulmonary edema and whether it attenuates pulmonary vascular permeability. Design:Prospective observational study. Setting:Twenty-bed medical intensive care unit of a tertiary medical center. Patients:Twenty patients with early-stage ARDS. Intervention:Volume expansion with a 500-mL infusion of 10% pentastarch (HES 200/0.5) at a rate of 10 mL/kg/hr. Measurements and Main Results:Baseline hemodynamics including systemic and pulmonary artery blood pressures, central venous pressure, pulmonary artery occlusion pressure, and cardiac output were obtained from an online HP Component Monitoring System and a pulmonary artery catheter. Intrathoracic blood volume (ITBV), global end-diastolic volume, extravascular lung water (EVLW), and pulmonary vascular permeability (EVLW/ITBV) were measured with a PiCCOplus monitor. Hemodynamic measurements were repeated immediately and 2, 4, and 6 hours after volume expansion. Pentastarch loading significantly increased central venous pressure, pulmonary artery occlusion pressure, pulmonary arterial pressures, and cardiac output. Pulmonary mechanics, venous admixtures, and EVLW values remained unchanged throughout the study. EVLW/ITBV significantly decreased immediately after the pentastarch infusion. Conclusions:In patients with early ARDS, pentastarch resuscitation significantly improved their hemodynamics and cardiac output without worsening pulmonary edema and pulmonary mechanics. It even attenuated pulmonary vascular permeability.