Pronóstico de los enfermos con enfermedad pulmonar obstructiva crónica reagudizada que precisan ventilación mecánica

OBJECTIVE

To determine the variables associated with prognosis for acute exacerbation of chronic obstructive pulmonary disease (AECOPD) in mechanically ventilated patients.

DESIGN

Prospective cohort study with retrospective analysis.

LOCATION

361 Intensive Care Units (ICU) in 20 countries.

PATIENTS AND METHODS

There were included in the study 522 patients who required mechanical ventilation for more than 12 hours due to an acute exacerbation of chronic obstructive pulmonary disease (AECOPD). In order to determine those variables associated with mortality, there was performed a recursive partition analysis in which the following variables were included: demographics, arterial blood gas prior to intubation, complications arising during mechanical ventilation (barotrauma, acute respiratory distress syndrome, ventilator-associated pneumonia, sepsis), organ dysfunction (cardiovascular, renal, liver, coagulation) and duration of ventilatory support.

INTERVENTIONS

None. VARIABLES OF PRIME IMPORTANCE: ICU mortality.

RESULTS

ICU and hospital mortality rates were 22% and 30%, respectively. Variables associated with mortality were cardiovascular dysfunction, renal dysfunction and duration of ventilatory support > 18 days. Median durations were as follows: mechanical ventilatory support, 4 days (P25: 2, P75: 6); weaning from ventilatory support, 2 days (P25: 1, P75: 5); stay in intensive care unit, 8 days (P25: 5, P75: 13); stay in hospital, 17 days (P25: 10, P75: 27).

CONCLUSIONS

Mortality in the studied cohort of patients with AECOPD was associated with cardiovascular dysfunction, renal dysfunction and prolonged mechanical support.

[Serum C-reactive protein as a marker of outcome and infection in critical care patients]

BACKGROUND AND OBJECTIVE

C-reactive protein (CRP) has been considered a marker for infection and an aid for diagnosing sepsis. We analyze the relation of CRP to infection and outcome in intensive care units (ICU) patients.

PATIENTS AND METHOD

Prospective study on 77 ventilated patients. Expected short ICU stay or (suspected or confirmed) infection at admission were excluding criteria. 55 admissions after elective surgery were the controls. CRP measurement the first (CRP-1), third (CRP-3) and sixth (CRP-6) day of stay. APACHE II (Acute Physiology Score and Chronic Health Evaluation), SOFA (Sepsis-related Organ Failure Assessment), shock, respiratory or renal failure, leucocytes, platelets and albumin were registered. Follow-up until day 9 for infection and ICU discharge for outcome.

RESULTS

CRP-1 in controls was 5.3 (3.9) mg/l and cases 67.8 (77.4) (p < 0.001). Shock on admission was related to CRP-1: patients in shock had higher CRP-1 levels (118.6 [82.8] vs 62.8 [75.6]; p = 0.06). 40.25% of cases developed infection, and CRP-1 levels were higher in this patients (88.8 [93.9] vs 53.8 [60.9]; p < 0.05). ROC area under curve was 0.6 with a sensibility of 23% and a specificity of 89% for a level of CRP-1 > 100. Mortality was 23.4% in cases and 1.8% in controls. Age, shock, APACHE II and SOFA were related to mortality, but CRP-1 did not. ROC area under curve for CRP-1 as mortality predictor in all patients was 0.62 (0.76 for APACHE II and 0.77 for SOFA) but only in cases was of 0.49 (0.69 for APACHE II and 0.67 for SOFA).

CONCLUSIONS

CRP level on admission is an useful marker for early infection but not for outcome in critically ill patients admited to the ICU.

La eterna promesa de la ventilación de alta frecuencia

High frequency oscillatory ventilation (HFOV) is based on the application of continuous pressure in the respiratory system, which assures oxygenation, on which a small oscillation that permits ventilation is added. Although this ventilation form seems to comply with the requirements necessary to minimize the pulmonary lesion associated to mechanical ventilator-induced lung injury in acute lung injury, as several experimental studies suggest, its advantages in the clinical practice must still be demonstrated. Part of this lack of evidence is due to methodological problems of the studies published. However, the major limitation is that it has not been compared against a conventional ventilation strategy with low volumes/pressures. At present, it seems that high frequency ventilation is limited to cases refractory to conventional ventilation. A more extensive knowledge on how to optimize high frequency ventilation is needed before proposing clinical trials having greater scope.

Gram-positive cocci infections in intensive care: guide to antibacterial selection

The incidence of multiresistance in Gram-positive cocci causing infections in critically ill patients admitted to the intensive care unit (ICU) has increased notably in recent years. Thus, therapeutic proposals have been modified according to the emergence of multiresistant cocci and adapted to epidemiological markers of individual infectious processes, geographical variations of these markers, the availability of new antibacterials, and advances in the knowledge of pharmacokinetic and pharmacodynamic aspects of their use. The current management of critically ill patients should consider new therapeutic approaches, such as the "de-escalating strategy", which includes the administration of empirical antibacterials active against multiresistant pathogens followed by directed treatment based on unequivocal data from antibacterial-susceptibility testing. Optimisation of antibacterial treatment should be viewed in the context of the need to determine plasma drug concentrations, pharmacoeconomic considerations and control of drug-related adverse events. Therapeutic proposals should be developed within the framework of the antibacterial policy of each hospital. The present review is focused on the description of the therapeutic strategies for the main infectious processes caused by Gram-positive cocci in severely ill patients admitted to the ICU according to a review of the pertinent literature and the clinical experience of the authors.

Neumonía nosocomial por Acinetobacter baumannii

Acinetobacter baumannii is a significant cause of nosocomial pneumonia, especially late ventilator-associated pneumonia. In Spain, A. baumannii is the third leading pathogen after Pseudomonas aeruginosa and Staphylococcus aureus. Risk factors for pneumonia due to A. baumannii are head injury, neurosurgery, acute respiratory distress syndrome, aspiration, and previous antibiotic therapy. Definitive diagnosis requires respiratory samples and invasive techniques with quantitative cultures to differentiate true infections from simple colonizations. The crude mortality of patients with ventilator-associated A. baumannii pneumonia is high, although the attributable mortality is controversial. Adequate empirical antimicrobial therapy of A. baumannii pneumonia is a protective factor, even though the therapeutic options are often limited. The treatment of choice is imipenem and sulbactam may be considered an acceptable alternative. Nowadays, colistin is the treatment of choice in A. baumannii pneumonia caused by panresistant strains. The associations of imipenem and rifampin or imipenem and sulbactam may be acceptable alternatives to colistin in infections caused by these strains. Surveillance measures are essential to eradicate this multidrug-resistant pathogen in outbreaks and reduce the number of episodes in endemic situations. Although these measures are important throughout the hospital, intensive care units are especially high-risk areas.

The Bispectral Index Scale: Its Use in the Detection of Brain Death

OBJECTIVE

To evaluate the Bispectral Index Scale (BIS) monitor as a method of brain death (BD) detection.

PATIENTS AND METHODS

We performed an observational prospective study in an intensive care unit (ICU) of a university hospital of 19 patients hospitalized nonconsecutively in the ICU with serious neurologic pathology and evolution toward BD. A BIS monitor, XP model, and the sensor "BIS Quatro" were used to continuously record values: suppression ratio (SR), quality of the signal index, and electromyographic (EMG) activity.

RESULTS

The BD diagnosis was made through neurological clinical exploration and electroencephalogram (EEG) in all the cases. Additionally, transcranial Doppler was used in 13 patients. Coincident with clinical worsening, it was observed that there was a gradual decrease of the BIS value, together with a rise in the SR. In all the patients in which the BD diagnosis was confirmed, the BIS showed values of 0 and suppression rates of 100. Only one patient showed interferences, due to EMG activity, the same problem was detected when a conventional EEG was performing. After using a neuromuscular blocker, the values of BIS and SR were 0 and 100, respectively.

CONCLUSIONS

The BIS is a noninvasive, simple, and easy to interpret method. All the patients with BD diagnosis except for one had a BIS value of 0 and TS of 100, showing a perfect correlation with the other diagnostic methods. The BIS cannot be used on its own for the confirmation of the BD, but it is a useful tool to detect the beginning of brain herniation.

[Bone scintigraphy with 99mTc-MDP in a patient with acute lymphoblastic leukemia initially diagnosed of Still's disease]

We present a 43-year-old male, who was admitted with the diagnosis of Adult-onset Still's disease, after several months of arthralgias, febricula and loss of weight. Chest x-ray, abdominal ultrasonography, chest, abdomen and pelvic CT scan and bone scintigraphy were performed. Scintigraphic findings oriented to the performance of a bone marrow biopsy with diagnosis of acute lymphoblastic leukemia.

Prognosis factors and outcome of community-acquired pneumonia needing mechanical ventilation

PURPOSE

To evaluate the variables associated with mortality of patients with community-acquired pneumonia who require mechanical ventilation and to determine the attributable morbidity and intensive care unit (ICU) mortality of community-acquired pneumonia.

MATERIAL AND METHODS

Retrospective cohort study carried out in 361 ICUs from 20 countries including 124 patients who required mechanical ventilation on the first day of admission to the hospital due to acute respiratory failure secondary to severe community-acquired pneumonia. To assess the factors associated with outcome, a forward stepwise logistic regression analysis was performed, and to determine the attributable mortality of community-acquired pneumonia, a matched study design was used.

RESULTS

We found 3 independent variables significantly associated with death in patients with community-acquired pneumonia requiring mechanical ventilation: simplified acute physiological score greater than 45 (odds ratio, 5.5 [95% confidence interval, 1.7-12.3]), shock (odds ratio, 5.7 [95% confidence interval, 1.7-10.1]), and acute renal failure (odds ratio, 3.0 [95% confidence interval, 1.1-4.0]). There was no statistically significant difference in ICU mortality among patients with or without community-acquired pneumonia (32% vs 35%; P=.59).

CONCLUSIONS

Community-acquired pneumonia needing mechanical ventilation is not a disease associated with higher mortality. The main determinants of patient outcome were initial severity of illness and the development of shock and/or acute renal failure.

M-study; arguments for regional trauma databases

BACKGROUND

The TRISS methodology, in combination with coefficients derived from the Major Trauma Outcome Study (MTOS), is the most widely used outcome prediction model for the care of trauma patients. Utilizing the M-statistic, different populations of trauma patients can be compared with the population originally enrolled in the MTOS.

PURPOSE

We hypothesized that databases outside of North-America would not be well matched to the MTOS study and thus the TRISS methodology would not accurately predict outcome in these different populations.

METHODS

All trauma studies utilizing TRISS methodology that were published between 1990-2003 were reviewed and M-statistics calculated based on the population described in the study. The populations were grouped by the following geographic locations: Europe, Asia/Africa and North-America.

RESULTS

The median M-statistic for Europe was 0.65, compared with 0.88 for Asian/African databases, and 0.90 for North-American studies. There was a significant difference between European and North-American studies (p < 0.05).

CONCLUSION

The trauma populations described in European studies differ significantly from the MTOS with respect to injury severity match, indicating the need for the development of regional trauma databases and modified TRISS coefficients based on the geographic location of the injured population included.

Case-Control Study of Nutritional Antioxidant Intake in Essential Tremor

The theory that oxidative stress is involved in the pathogenesis of neurodegenerative diseases has received considerable attention and studies have linked these diseases to the diminished use of antioxidant vitamins (vitamins E and C) and other dietary antioxidants. Essential tremor (ET) is a chronic, progressive disease. One possible disease mechanism is neurodegenerative. Whether nutritional antioxidant use differs between ET cases and controls is not known. Using a case-control design, we conducted detailed dietary assessments and tested the hypothesis that diminished use of nutritional antioxidants is associated with ET. Data on diet were collected on 156 ET cases and 220 controls using a semi-quantitative food-frequency questionnaire. There was no evidence that current nutritional antioxidant exposure differs in ET cases and controls. This does not exclude the possibility that nutritional antioxidant exposure was lower in ET cases prior to their disease onset.

Cefepime and continuous renal replacement therapy (CRRT): In vitro permeability of two CRRT membranes and pharmacokinetics in four critically ill patients

BACKGROUND

Cefepime is a fourth-generation cephalosporin with a broad spectrum of antimicrobial activity against gram-positive and gram-negative micro-organisms. It is a useful option for treating infections in critically ill patients in intensive care due to its high degree of activity and its tolerability.

OBJECTIVE

The aim of this study was to characterize in vitro the permeability to cefepime of 2 membranes frequently used in continuous renal replacement therapies (CRRTs). An in vivo study was also carried out to determine the pharmacokinetics of cefepime in critically ill patients undergoing CRRT.

METHODS

In vitro procedures were conducted in 3 different fluids using polyacrylonitrile (AN69) or polysulfone (PS) membranes. Continuous venovenous hemofiltration (CVVH) and continuous venovenous hemodialysis (CVVHD) were simulated. Four male patients undergoing CVVH or continuous venovenous hemodiafiltration, who received 2000 mg of cefepime intravenously every 8 hours, entered the in vivo study. Prefilter and ultrafiltrate samples were collected, and concentrations of cefepime were measured using high-performance liquid chromatography. The sieving coefficient (Sc), defined as the fraction of drug eliminated across the membrane, and the saturation coefficient (Sa), defined as the fraction of drug diffused through the membrane to the dialysate fluid, were analyzed. Pharmacokinetic parameters were determined according to a noncompartmental analysis.

RESULTS

The patients ranged in age from 18 to 75 years and weighed from 65 to 80 kg. By analyzing Sc and Sa values in the in vitro procedures, no differences were detected in the permeability of AN69 or PS membranes to cefepime in CVVH or CVVHD. Sc/Sa values were between 0.93 and 1.03 in Ringer's lactate and in bovine albumin-containing Ringer's lactate samples, but Sc/Sa values were lower in plasma samples (0.82-0.95). In the in vivo portion of the study, the patients' mean (SD) Sc/Sa value was 0.76 (0.21) and correlated well with the fraction unbound to proteins (0.79 [0.09]). Clearance by CRRT (mean [SD]) was 29.0 (16.8)% of the total clearance. Serum elimination t(1/2) was 4.6 (0.9) hours, and the volume of distribution at steady state was 0.6 (0.3) L/kg (mean [SD] values).

CONCLUSIONS

Cefepime was significantly removed by CRRT. No significant differences were found in the Sc or Sa of cefepime between AN69 and PS membranes used in the CVVH or CVVHD procedures. The clearance of cefepime by CRRT must be considered when dosing critically ill patients.

Multicenter study of the multiple organ dysfunction syndrome in intensive care units: the usefulness of Sequential Organ Failure Assessment scores in decision making

OBJECTIVE

This study examined the incidence and mortality of multiple organ dysfunction syndrome (MODS) in intensive care units, evaluated the limitation of life support in these patients, and determined whether daily measurement of the Sequential Organ Failure Assessment (SOFA) is useful for decision making.

DESIGN AND SETTING

Prospective, observational study in 79 intensive care units.

PATIENTS AND PARTICIPANTS

Of the 7,615 patients admitted during a 2-month period we found 1,340 patients to have MODS.

MEASUREMENTS AND RESULTS

We recorded mortality and length of stay in the intensive care unit and the hospital and the maximum and minimum total SOFA scores during MODS. Limitation of life support in MODS patients was also evaluated. Stepwise logistic regression was used to determine the factors predicting mortality. The in-hospital mortality rate in patients with MODS was 44.6%, and some type of limitation of life support was applied in 70.6% of the patients who died. The predictive model maximizing specificity included the following variables: maximum SOFA score, minimum SOFA score, trend of the SOFA for 5 consecutive days, and age over 60 years. The model diagnostic yield was: specificity 100%, sensitivity 7.2%, positive predictive value 100%, and negative predictive value 57.3%; the area under the receiver operating characteristic curve was 0.807.

CONCLUSIONS

This model showed that in our population with MODS those older than 60 years and with SOFA score higher than 9 for at least 5 days were unlikely to survive.

[Identification of risk times for dissemination of methicillin-resistant Staphylococcus aureus in an intensive care unit]

BACKGROUND AND OBJECTIVE

The dissemination of methicillin-resistant Staphylococcus aureus (MRSA) in patients admitted to an Intensive Care Unit (ICU) depends, among other reasons, on the time interval between obtention of the first positive sample and the establishment of measures for contact isolation. The objective of this study was to identify the risk intervals for the spread of MRSA in ICU patients and to assess the relationship between these periods and the development of new cases of MRSA acquired in the ICU.

MATERIAL AND METHOD

Observational and prospective study, which was carried out in a 18-bed polyvalent ICU during a 49-month period (October 1998-October 2002). The exposure risk period was defined as the time elapsed between obtention of the first positive sample and contact isolation of the index case, and the window period as the time elapsed between recovery of the last negative sample to the first positive sample. Infection sources of MRSA were classified into community-acquired and hospital-acquired (nosocomial extra-ICU and nosocomial intra-ICU infections).

RESULTS

MRSA was isolated in 69 (2.73%) of 2,531 patients admitted to the ICU during the study period and in all patients measures of contact isolation were indicated. Community-acquired MRSA was diagnosed in 9 (13%) cases, nosocomial intra-ICU in 29 (42%), and nosocomial extra-ICU in 31 (44.9%). The mean duration of the exposure risk period was 3.1 (SD 2.2) (median 3, range 0-9) days and the window period 2.9 (SD 4.6) (median 1, range 0-28) days. In 18 of the 29 cases of intra-ICU-acquired MRSA (62.1%; 95% CI, 42.3-79.3), the infection was acquired within the exposure risk and/or window periods of other patients with MRSA.

CONCLUSIONS

The exposure risk periods and the window periods showed a strong relationship between detection of new cases of intra-ICU colonization and/or infection by MRSA.

In-hospital and 2-year survival of patients treated with mechanical ventilation for acute exacerbation of COPD

OBJECTIVE

To analyze in-hospital and 2-year survival of patients who require mechanical ventilation with intubation after acute respiratory failure due to exacerbation of chronic obstructive pulmonary disease (COPD). The secondary objective was to identify the prognostic factors for in-hospital mortality and mortality at 2 years.

PATIENTS AND METHODS

We retrospectively studied 101 patients with suspected COPD admitted to the intensive care unit between July 1993 and December 1998. Variables potentially related to mortality were analyzed with a univariate model and by logistic regression.

RESULTS

In-hospital survival was 74.3% and 2-year survival was 55.4%. Survival at 2 years was 81% for patients discharged from hospital. The variables associated with in-hospital mortality were age greater than 65 years, electrocardiographic diagnosis of chronic cor pulmonale, and development of multiorgan dysfunction syndrome. No factors predictive of mortality at 2 years were identified.

CONCLUSIONS

The in-hospital survival rate for patients with an acute exacerbation of COPD who require mechanical ventilation is good and the 2-year survival rate is acceptable. Age, electrocardiographic signs of cor pulmonale, and development of multiorgan dysfunction syndrome were associated with greater risk of in-hospital mortality.

Physico-chemical stability and sterility of previously prepared saline infusion solutions for use in out-of-hospital emergencies

OBJECTIVE

The topic of this research was to determine whether out-of-hospital emergency teams could make use of previously prepared saline solutions (SS). The objective was to discover the physical, chemical and sterility characteristics of previously prepared saline infusions stored in ambulances and ascertain how long they remained in optimum condition.

METHOD

Randomised clinical trial, triple blind, where study units consisted of saline solutions prepared with an infusion system and a three-way valve. The duration of the study was 12 months. Six intervention groups were designed on the basis of time of exposure and location. Samples consisted of 672 units. Twelve microbiological cultures were made and the pH, density, viscosity and CINa concentration were determined. We compared hypotheses with four models of linear regression for the variables and a model of logistic regression for the variables. A value of P < 0.05 was considered significant.

RESULTS

We obtained results from 669 saline solutions (98.82%). Neither multivariant analysis nor ANOVA tests showed any significant association for a power greater than 99% with regard to the physical-chemical characteristics. The model of logistic regression also did not find any significant association for sterility. Colonisation was present in 1.7% of the 8,028 cultures made and more than 5 CFU per millilitre was found in only two cases.

CONCLUSION

There is no evidence to suggest that recently prepared saline infusion solutions are any different from a physical-chemical and sterility point of view than those exposed for 24, 48, or 72 h. It was concluded that use can be made of previously prepared saline solutions with a guarantee their stability and sterility.

[Semiautomatic defibrillation in children]

The main survival factor in cardiac arrest secondary to ventricular fibrillation (VF) is the interval between collapse and defibrillation; consequently, this treatment constitutes one of the most important links in the survival chain in adults. Although VF is a rare cause of out-of-hospital cardiac arrest in children, its detection and treatment is essential because in the pediatric cardiac arrest scenario, VF is the dysrhythmia with the best prognosis. Automated external defibrillators (AED) are simple devices that allow cardiac rhythm to be analyzed; they can also determine whether it is shockable or not with high sensitivity and specificity in adults and children. Currently available evidence has prompted the recommendation of AED use in children older than 1 year without signs of circulation, mainly in the pre-hospital setting and ideally with a dose-limiting device.

Heart rate variability as early marker of multiple organ dysfunction syndrome in septic patients

PURPOSE

To determine whether measuring heart rate variability (HRV) in a group of septic patients without multiple organ dysfunction syndrome (MODS) made it possible to predict which of them would later develop this syndrome.

MATERIAL AND METHODS

We studied 46 septic patients without MODS at the time of admission to an intensive care unit (ICU). During the first 24 hours of admission, a 10-minute electrocardiogram (ECG) was performed and 8 HRV indexes were calculated off-line. Eleven patients later developed MODS (MODS group) during their ICU stay, and 28 did not (non-MODS group). Seven patients were excluded.

RESULTS

Although Acute Physiological and Chronic Health Evaluation (APACHE II) scores were similar for both groups, most HRV indices on admission were reduced significantly in the MODS group. Compared with a subset from the non-MODS group (control group, n = 11) paired by age, the MODS group had significantly lower low-frequency spectral components (LF, P =.0128) and mean squared successive differences of R-R intervals (rMSSD) (P =.0473) values. Multivariable logistic regression identified LF as the best predictor of MODS and received operating characteristic (ROC) curves established its cut-off point at 18 ms(2). Mortality rates were 63.6% for the MODS group and 0% for the non-MODS group (P <.0001).

CONCLUSIONS

Reduction of HRV on ICU admission may be useful in identifying septic patients at risk for development of MODS.