Aplicaciones clínicas de la ecuación del movimiento del sistema respiratorio para la toma de decisiones en el paciente bajo ventilación mecánica invasiva: artículo de reflexión

Introducción: la ventilación mecánica es una práctica común en las unidades de cuidados intensivos y anestesiología. Tiene implicaciones terapéuticas, pero también es potencialmente nociva para el sistema respiratorio y los órganos distantes, por lo cual es imprescindible monitorizar los parámetros ventilatorios de manera continua. Objetivo: describir la ecuación del movimiento del sistema respiratorio y sus aplicaciones clínicas en el paciente bajo ventilación mecánica. Desarrollo: la ecuación del movimiento del sistema respiratorio integra las fuerzas dinámicas generadas por el ventilador y las propiedades intrínsecas del pulmón y la caja torácica. Expresa la presión en el sistema respiratorio en relación con el volumen, la elastancia, la resistencia, el flujo de aire y las presiones generadas por el ventilador y el paciente. Las presiones elevadas en el sistema respiratorio se asocian a una mayor mortalidad en pacientes con ventilación mecánica, por lo que la identificación de los componentes que condicionan la elevación de las presiones mediante la ecuación del movimiento del sistema respiratorio permite realizar modificaciones a los parámetros programados del ventilador para mantener una ventilación protectora. Conclusión: la toma de decisiones basada en la ecuación del movimiento del sistema respiratorio permite realizar ajustes en los parámetros ventilatorios según las características y enfermedades del paciente bajo ventilación mecánica.

Bioinformatics-Based Characterization of Proteins Related to SARS-CoV- 2 Using the Polarity Index Method® (PIM®) and Intrinsic Disorder Predisposition

Background:

The global outbreak of the 2019 novel Coronavirus Disease (COVID-19) caused by the infection with the Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2), which appeared in China at the end of 2019, signifies a major public health issue at the current time.

Objective:

The objective of the present study is to characterize the physicochemical properties of the SARS-CoV-2 proteins at a residues level, and to generate a “bioinformatics fingerprint” in the form of a “PIM® profile” created for each sequence utilizing the Polarity Index Method® (PIM®), suitable for the identification of these proteins.

Methods:

Two different bioinformatics approaches were used to analyze sequence characteristics of these proteins at the residues level, an in-house bioinformatics system PIM®, and a set of the commonly used algorithms for the predic-tion of protein intrinsic disorder predisposition, such as PONDR® VLXT, PONDR® VL3, PONDR® VSL2, PONDR® FIT, IUPred_short and IUPred_long. The PIM® profile was generated for four SARS-CoV-2 structural proteins and compared with the corresponding profiles of the SARS-CoV-2 non-structural proteins, SARS-CoV-2 putative proteins, SARS-CoV proteins, MERS-CoV proteins, sets of bacterial, fungal, and viral proteins, cell-penetrating peptides, and a set of intrinsically disordered proteins. We also searched for the UniProt proteins with PIM® profiles similar to those of SARS-CoV-2 structural, non-structural, and putative proteins.

Results:

We show that SARS-CoV-2 structural, non-structural, and putative proteins are characterized by a unique PIM® profile. A total of 1736 proteins were identified from the 562,253 “reviewed” proteins from the UniProt database, whose PIM® profile was similar to that of the SARS-CoV-2 structural, non-structural, and putative proteins.

Conclusion:

The PIM® profile represents an important characteristic that might be useful for the identification of proteins similar to SARS-CoV-2 proteins.

Bioinformatics-Based Identification of Selective Cationic Amphipatic Antibacterial Peptides: Aurein 1.2 Variants Case

Background:

Selective Cationic Amphipathic Antibacterial Peptides (SCAAPs) occupy a prominent place in the production of new drugs on account of their high toxicity towards bacteria and low toxicity towards mammalian cells, low hemolytic activity, and contribution to the protection of the human immune system.

Aim:

their number in nature is very low, and experimental tests are very protracted and costly. Therefore, it would be useful to have bioinformatics tools that would identify them in the existing databases and also propose new synthetic SCAAPs.

Methods:

In order to reduce the costs of identification and/or chemical synthesis and to know the physicochemical characteristics of SCAAPs at a residues level and to obtain a “bioiformatics fingerprint” suitable for their selection, we have modified the Polarity Index Method® (PIM®) and the α-helical configuration of each sequence is included in determining their individual “PIM® profile”. We have also used a set of the computer program to determine their “Intrinsic Disorder Predisposition”. This information was then compared with other protein groups, such as bacteria, fungi, virus and Cell-Penetrating Peptides (CPP) from the UniProt database and a set of intrinsically disordered proteins. Once the “fingerprint” of SCAAPs was obtained, it was used for searching among the 559228 “reviewed” proteins from the UniProt database and a set of synthetic SCAAPs characterized by the predefined “PIM® profile” selected.

Results:

Our results showed that the metric named “PIM® profile” can identify, with a high level of accuracy, a group of bacterial SCAAPs. This bioinformatics study was supported at residues level, using the in-house bioinformatics system Polarity Index Method the commonly used algorithm for the prediction of intrinsic disorder predisposition, PONDR® FIT.

Conclusions:

The Polarity Index Method seems highly efficient identifying SCAAP candidates.

Impact of obesity and diabetes mellitus in critically ill patients with SARS-CoV-2

PURPOSE

Evaluate the associations of obesity and diabetes with the risk of mortality in critically ill patients infected with SARS-CoV-2.

MATERIALS AND METHODS

This cohort study included 115 adult patients admitted to the ICU with SARS-CoV-2 pneumonia. Anthropometric variables and biochemical (C-reactive protein, ferritin, leukocyte, neutrophils, and fibrinogen) were measured. Multivariate logistic regression analyses were used to investigate the associations.

RESULTS

Mean age was 50.6±11.2 years, 68.7% were male. Median BMI was 30.9kg/m². All patients had invasive mechanical ventilation. Patients with diabetes had increased risk of mortality with OR of 2.86 (CI 95% 1.1-7.4, p=0.026); among those patients who, in addition to diabetes had obesity, the risk was de 3.17 (CI 95% 1.9-10.2, p=0.038). Patients with obesity had 1.25 times greater risk of developing a severe SARS-CoV-2 infection (95% CI 1.09-1.46, p=0.025). Negative correlation was observed between BMI and the PaO2/FiO2 ratio (r=-0.023, p<0.05). Obese patients required more days of mechanical ventilation and longer hospital stay compared to non-obese patients.

CONCLUSIONS

Diabetes and obesity are risk factors for increasing severity of SARS-CoV-2 infection, and they are both associated with an increase in mortality.

Bioinformatics-based Identification of Proteins Expressed by Arthropod- borne Viruses Transmitted by Aedes Aegypti Mosquito

Background:

The female Aedes aegypti mosquito is a vector of several arthropod-borne viruses, such as Mayaro, Dengue, Chikungunya, Yellow Fever, and Zika. These viruses cause the death of at least 600000 people a year and temporarily disable several million more around the world. Up to date, there are no effective prophylactic measures that would prevent the contact and bite of this arthropod and, therefore, its consequential contagion.

Objective:

The objective of the present study was to search for the regularities of the proteins expressed by these five viruses, at residues level, and obtain a “bioinformatic fingerprint” to select them.

Methods:

We used two bioinformatic systems, our in-house bioinformatic system named Polarity Index Method® (PIM®) supported at residues level, and the commonly used algorithm for the prediction of intrinsic disorder predisposition, PONDR® FIT. We applied both programs to the 29 proteins that express the five groups of arboviruses studied, and we calculated for each of them their Polarity Index Method® profile and their intrinsic disorder predisposition. This information was then compared with analogous information for other protein groups, such as proteins from bacteria, fungi, viruses, and cell-penetrating peptides from the UniProt database, and a set of intrinsically disordered proteins. Once the “fingerprint” of each group of arboviruses was obtained, these “fingerprints” were searched among the 559228 “reviewed” proteins from the UniProt database.

Results:

In total, 1736 proteins were identified from the 559228 “reviewed” proteins from the UniProt database, with similar “PIM® profile” to the 29 mutated proteins that express the five groups of arboviruses.

Conclusion:

We propose that the “PIM® profile” of characterization of proteins might be useful for the identification of proteins expressed by arthropod-borne viruses transmitted by Aedes aegypti mosquito.

Simultaneous mechanical ventilation of several patients with a single ventilator

Introduction

Simultaneous mechanical ventilation of several patients with a single ventilator might reduce the deficit of these devices for the care of patients with acute respiratory failure due to Covid-19.

Objective

To communicate the results of a mechanical ventilation exercise with a ventilator in a lung simulator, and simultaneously in two and four.

Results

No statistically significant differences were observed between programmed, recorded and measured positive end-expiratory pressure, mean airway pressure and peak pressure, except when simultaneously ventilating four lung simulators.

Conclusions

Simultaneous mechanical ventilation should be implemented by medical personnel with experience in the procedure, be restricted to two patients and carried out in the intensive care unit.

Simultaneous mechanical ventilation of several patients with a single ventilator

INTRODUCTION

Simultaneous mechanical ventilation of several patients with a single ventilator might reduce the deficit of these devices for the care of patients with acute respiratory failure due to Covid-19.

OBJECTIVE

To communicate the results of a mechanical ventilation exercise with a ventilator in a lung simulator, and simultaneously in two and four.

RESULTS

No statistically significant differences were observed between programmed, recorded and measured positive end-expiratory pressure, mean airway pressure and peak pressure, except when simultaneously ventilating four lung simulators.

CONCLUSIONS

Simultaneous mechanical ventilation should be implemented by medical personnel with experience in the procedure, be restricted to two patients and carried out in the intensive care unit.

Electronegativity and intrinsic disorder of preeclampsia-related proteins

Preeclampsia, hemorrhage, and infection are the leading causes of maternal death in underdeveloped countries. Since several proteins associated with preeclampsia are known, we conducted a computational study which evaluated the commonness and potential functionality of intrinsic disorder of these proteins and also made an attempt to characterize their origin. The origin of the preeclampsia-related proteins was assessed with a supervised technique, a Polarity Index Method (PIM), which evaluates the electronegativity of proteins based solely on their sequence. The commonness of intrinsic disorder was evaluated using several disorder predictors from the PONDR family, the charge-hydropathy plot (CH-plot) and cumulative distribution function (CDF) analyses, and using the MobiDB web-based tool, whereas potential functionality of intrinsic disorder was studied with the D2P2 resource and ANCHOR predictor of disorder-based binding sites, and the STRING tool was used to build the interactivity networks of the preeclampsia-related proteins. Peculiarities of the PIM-derived polar profile of the group of preeclampsia-related proteins were then compared with profiles of a group of lipoproteins, antimicrobial peptides, angiogenesis-related proteins, and the intrinsically disordered proteins. Our results showed a high graphical correlation between preeclampsia proteins, lipoproteins, and the angiogenesis proteins. We also showed that many preeclampsia-related proteins contain numerous functional disordered regions. Therefore, these bioinformatics results led us to assume that the preeclampsia proteins are highly associated with the lipoproteins group, and that some preeclampsia-related proteins contain significant amounts of functional disorders.

[Reflections concerning the care process in the emergency medical services]

In this paper we share some reflections regarding the care process in the emergency medical services, as well as some of the challenges with which these fundamental services deal. We highlight the increasing amount of patients and the complexity of some of the clinical cases, which are some of the causes that lead to the overcrowding of these services.

Classifying lipoproteins based on their polar profiles

The lipoproteins are an important group of cargo proteins known for their unique capability to transport lipids. By applying the Polarity index algorithm, which has a metric that only considers the polar profile of the linear sequences of the lipoprotein group, we obtained an analytical and structural differentiation of all the lipoproteins found in UniProt Database. Also, the functional groups of lipoproteins, and particularly of the set of lipoproteins relevant to atherosclerosis, were analyzed with the same method to reveal their structural preference, and the results of Polarity index analysis were verified by an alternate test, the Cumulative Distribution Function algorithm, applied to the same groups of lipoproteins.

Identification of proteins associated with Mycobacterium tuberculosis virulence pathway by their polar profile

With almost one third of the world population infected, tuberculosis is one of the most devastating diseases worldwide and it is a major threat to any healthcare system. With the mathematical-computational method named "Polarity Index Method", already published by this group, we identified, with high accuracy (70%), proteins related to Mycobacterium tuberculosis bacteria virulence pathway from the Tuberculist Database. The test considered the totality of proteins cataloged in the main domains: fungi, bacteria, and viruses from three databases: Antimicrobial Peptide Database (APD2), Tuberculist Database, Uniprot Database, and four antigens of Mycobacterium tuberculosis: PstS-1, 38-kDa, 19-kDa, and H37Rv ORF. The method described was calibrated with each database to achieve the same performance, showing a high percentage of coincidence in the identification of proteins associated with Mycobacterium tuberculosis bacteria virulence pathway located in the Tuberculist Database, and identifying a polar pattern regardless of the group studied. This method has already been used in the identification of diverse groups of proteins and peptides, showing that it is an effective discriminant. Its metric considers only one physico-chemical property, i.e. polarity.

[Índice de Saturación Modificado y Ambulancias (ISMA): Ambulance assignment and remote Emergency Room Bed Reservation]

INTRODUCTION

In most places all over the world–including our country–services in emergency rooms are oversaturated. This situation frequently forces the continuously arriving ambulances to be redirected to other medical units, delaying the admission of patients moved and thus adversely affecting their physical condition.

OBJECTIVE

To introduce an improvement to the Índicede Saturación Modificado computational system, which monitors the degree of saturation of a network of emergency medical services, to include a network of ambulances, enabling in the system: (i) the effective allocation of ambulances to the site of the accident, or severe clinical event, and (ii) the remote booking of beds in the nearest and least saturated emergency room available.

MATERIAL AND METHODS

The evaluation and connectivity of the computational improvement to the Índicede Saturación Modificado system was carried out with a computational test verifying these two aspects, using only differences in postal codes, for time measuring.

RESULTS

The verification of its sustainability online showed the new Índice de Saturación Modificado y Ambulancias system (ISMA) has a robust structure capable of being adapted to mobile phones, laptops or tablets, and can efficiently administrate: (i) the quantification of excessive demand in the emergency room services of a hospital network, (ii) the allocation of ambulances attending the site of the event or contingency, and (iii) the allocation of ambulances and patients, in the best distance-time conditions, from the site of the accident or clinical event to the nearest and least saturated emergency room service.

CONCLUSIONS

This administrative management tool is efficient and simple to use, and it optimally relates independent service networks.

Identification of proteins associated with amyloidosis by polarity index method

There is a natural protein form, insoluble and resistant to proteolysis, adopted by many proteins independently of their amino acid sequences via specific misfolding-aggregation process. This dynamic process occurs in parallel with or as an alternative to physiologic folding, generating toxic protein aggregates that are deposited and accumulated in various organs and tissues. These proteinaceous deposits typically represent bundles of β-sheet-enriched fibrillar species known as the amyloid fibrils that are responsible for serious pathological conditions, including but not limited to neurodegenerative diseases, grouped under the term amyloidoses. The proteins that might adopt this fibrillar conformation are some globular proteins and natively unfolded (or intrinsically disordered) proteins. Our work shows that intrinsically disordered and intrinsically ordered proteins can be reliably identified, discriminated, and differentiated by analyzing their polarity profiles generated using a computational tool known as the polarity index method (Polanco & Samaniego, 2009; Polanco et al., 2012; 2013; 2013a; 2014; 2014a; 2014b; 2014c; 2014d). We also show that proteins expressed in neurons can be differentiated from proteins in these two groups based on their polarity profiles, and also that this computational tool can be used to identify proteins associated with amyloidoses. The efficiency of the proposed method is high (i.e. 70%) as evidenced by the analysis of peptides and proteins in the APD2 database (2012), AVPpred database (2013), and CPPsite database (2013), the set of selective antibacterial peptides from del Rio et al. (2001), the sets of natively unfolded and natively folded proteins from Oldfield et al. (2005), the set of human revised proteins expressed in neurons, and non-human revised proteins expressed in neurons, from the Uniprot database (2014), and also the set of amyloidogenic proteins from the AmyPDB database (2014).

[An automated registry program for nosocomial infections]

Las infecciones nosocomiales presentan un gran reto para la medicina hospitalaria, en general, y para las Unidades de Cuidados Intensivos, en particular. Su elevada prevalencia, la gran morbilidad y mortalidad asociadas, el incremento de la estancia hospitalaria y, en consecuencia, los costos de la atención médica han hecho que los programas de vigilancia, control y prevención de infecciones nosocomiales sean una parte toral de los protocolos de seguridad para el paciente y un indicador de calidad de la atención médica.

Possible computational filter to detect proteins associated to influenza A subtype H1N1

The design of drugs with bioinformatics methods to identify proteins and peptides with a specific toxic action is increasingly recurrent. Here, we identify toxic proteins towards the influenza A virus subtype H1N1 located at the UniProt database. Our quantitative structure-activity relationship (QSAR) approach is based on the analysis of the linear peptide sequence with the so-called Polarity Index Method that shows an efficiency of 90% for proteins from the Uniprot Database. This method was exhaustively verified with the APD2, CPPsite, Uniprot, and AmyPDB databases as well as with the set of antibacterial peptides studied by del Rio et al. and Oldfield et al.

Possible computational filter to detect proteins associated to influenza A subtype H1N1

The design of drugs with bioinformatics methods to identify proteins and peptides with a specific toxic action is increasingly recurrent. Here, we identify toxic proteins towards the influenza A virus subtype H1N1 located at the UniProt database. Our quantitative structure-activity relationship (QSAR) approach is based on the analysis of the linear peptide sequence with the so-called Polarity Index Method that shows an efficiency of 90% for proteins from the Uniprot Database. This method was exhaustively verified with the APD2, CPPsite, Uniprot, and AmyPDB databases as well as with the set of antibacterial peptides studied by del Rio et al. and Oldfield et al.

[Modified overcrowd index in emergency room]

INTRODUCTION

Overcrowd of emergency rooms affects efficiency and quality of medical care.

OBJECTIVES

To describe the mathematical-computational system modified overcrowd index which measures in real time and in four levels of warnings (non crowded, crowded, overcrowded and extreme overcrowded) emergency room saturation in a network of hospitals, from only seven simple variables (number of available beds, physicians and nurses, number of patients in the waiting room, in medical consultation and admitted for further evaluation, as well as number of critically ill patients admitted).

MATERIALS AND METHODS

The modified overcrowd index was exhaustively tested with 245,280 virtual transactions from seven hospitals in an uninterrupted schedule basis simulating hourly surveillance for four years.

RESULTS

From 224 episodes of overcrowd, 216 (97%) where correctly identified and verified by the network of hospitals warnings, its time series also provided useful information about available personnel and resource distribution within the hospital network.

CONCLUSIONS

Modified overcrowd index is an efficient tool detecting emergency room overcrowd outbreaks in a network of hospitals.

Detection of selective antibacterial peptides by the Polarity Profile method

Antimicrobial peptides occupy a prominent place in the production of pharmaceuticals, because of their effective contribution to the protection of the immune system against almost all types of pathogens. These peptides are thoroughly studied by computational methods designed to shed light on their main functions. In this paper, we propose a computational approach, named the Polarity Profile method that represents an improvement to the former Polarity Index method. The Polarity Profile method is very effective in detecting the subgroup of antibacterial peptides called selective cationic amphipathic antibacterial peptides (SCAAP) that show high toxicity towards bacterial membranes and exhibit almost zero toxicity towards mammalian cells. Our study was restricted to the peptides listed in the antimicrobial peptides database (APD2) of December 19, 2012. Performance of the Polarity Profile method is demonstrated through a comparison to the former Polarity Index method by using the same sets of peptides. The efficiency of the Polarity Profile method exceeds 85% taking into account the false positive and/or false negative peptides.

Detection of selective antibacterial peptides by the Polarity Profile method

Antimicrobial peptides occupy a prominent place in the production of pharmaceuticals, because of their effective contribution to the protection of the immune system against almost all types of pathogens. These peptides are thoroughly studied by computational methods designed to shed light on their main functions. In this paper, we propose a computational approach, named the Polarity Profile method that represents an improvement to the former Polarity Index method. The Polarity Profile method is very effective in detecting the subgroup of antibacterial peptides called selective cationic amphipathic antibacterial peptides (SCAAP) that show high toxicity towards bacterial membranes and exhibit almost zero toxicity towards mammalian cells. Our study was restricted to the peptides listed in the antimicrobial peptides database (APD2) of December 19, 2012. Performance of the Polarity Profile method is demonstrated through a comparison to the former Polarity Index method by using the same sets of peptides. The efficiency of the Polarity Profile method exceeds 85% taking into account the false positive and/or false negative peptides.

[New device and technique to measure intra-abdominal pressure]

INTRODUCTION

sequential measurement of intra-abdominal pressure is of paramount importance for an early detection and appropriate therapeutic management of intra-abdominal hypertension and abdominal compartment syndrome.

OBJECTIVE

to validate a device and technique developed to measure intra-abdominal pressure (an innovation of the Foley urinary catheter named intra-abdominal pressure catheter).

METHODS

three different sets of measurements where done to test the intra-abdominal pressure catheter device: I. 50 measurements were done with the intra-abdominal pressure catheter device and compared against those measurements done using a manometer graded in cm H(2)O; II. Direct measurement of intra-abdominal pressure in five patients during elective laparoscopy vs the intraabdominal pressure catheter device; and III. Measurement of intra-abdominal pressure by the Kron method (Gold standard) vs intra-abdominal pressure catheter device in three patents with intra-abdominal hypertension/abdominal compartment syndrome. Measurements where compared with Pearson correlation test and Bland Altman statistics.

RESULTS

I.Intra-abdominal pressure catheter vs graded manometer: r = 0.99, with a mean pressure difference of 0.27 ± 0.23 mmHg, CI (0.039 to 0.092 mmHg). II. Direct measurement of intra-abdominal pressure during laparoscopy vs intra-abdominal pressure catheter device: r = 0.93, with a mean pressure difference of 0.18 ± 0.84 mmHg, CI (-1.46 to 1.83 mmHg) and III. Measurement of intra-abdominal pressure by the Kron Method vs intra-abdominal pressure catheter device: r = 0.81, with a mean pressure difference of -0.41 ± 0.87, CI (-2.12 mmHg to 1.30 mmHg).

CONCLUSIONS

the intra-abdominal pressure catheter device is a safe and reliable instrument for measuring intra-abdominal pressure.

Characterization of a possible uptake mechanism of selective antibacterial peptides

Selective antibacterial peptides containing less than 30 amino acid residues, cationic, with amphipathic properties, have been the subject of several studies due to their active participation and beneficial effects in strengthening the immune system of all living organisms. This manuscript reports the results of a comparison between the group of selective antibacterial peptides and another group called "cell penetrating peptides". An important number of the selective antibacterial peptides are cell penetrating peptides, suggesting that their toxicity is related to their uptake mechanism. The verification of this observation also includes the adaptation of a method previously published, called Polarity index, which reproduces and confirms the action of this new set of peptides. The efficiency of this method was verified based on four different databases, yielding a high score. The verification was based exclusively on the peptides already reported in the databases which have been experimentally verified.

[Survey about responsiveness of third-level hospitals to a medical disaster: after the pandemic influenza in Mexico]

BACKGROUND

The recent pandemic influenza AH1N1 virus made it clear that planning for medical disaster response is critical.

OBJECTIVE

To know the responsiveness of a sample of highly specialized hospitals in Mexico to a medical disaster, with the previous pandemic influenza AH1N1 as reference.

METHODS

A survey was conducted among the Medical Directors of a sample of highly specialized hospitals, covering: previous experience with the pandemic influenza, space considerations, material resources, staff, logistics, and current general perspectives. Descriptive statistics were used for analysis.

RESULTS

A 95% response was obtained from the institutions (19 hospitals). Of these, 47.4% considered that the medical institution was not ready to respond to pandemic influenza. The median surge capacity for the Intensive Care Unit beds was 30% (range 0 to 32 beds). The least reserve in medication was found in the antivirals (26.3%). Only 47.4% considered having enough intensive care nurses and 57.9% enough respiratory technicians; 42.1% would not have an easy access to resources in an emergency.

CONCLUSIONS

Prevention is key in responsiveness to medical disasters, and therefore the basic steps for planning strategies must be considered.

[Constrictive pericarditis: the story of a constrained heart]

BACKGROUND

Symptoms of constrictive pericarditis may be nonspecific, misleading and may delay or lead to an incorrect diagnosis.

CLINICAL CASE

We present the case of a 28-year-old male who was admitted to the hospital with progressive dyspnea, thoracic pain and a history of 25 kg of weight gain during the last 2 years. He was evaluated at another facility and his clinical presentation led to an erroneous diagnosis of primary hepatic disease (cirrhosis and portal hypertension). Physical examination showed that he was dyspneic, emaciated, had marked distention of his frontal cranial veins, diminished heart sounds, massive ascites and leg edema. Laboratory tests reported abnormal liver function tests and abdominal paracentesis chylous ascites. Electrocardiogram showed sinus rhythm with generalized low voltage and nonspecific repolarization changes. Heart size was normal on chest radiography. Doppler echocardiography reported bilateral atrial dilatation, a thickened pericardium and a short deceleration time of transmitral flow. A thickened and calcified pericardium was seen on CT scan. Pericardiectomy was performed. Spontaneous polyuria was observed during and after surgery with subsequent improvement of ascites and edema. The pericardium was found to be grossly thickened and inflamed.

CONCLUSIONS

Clinician must be aware of the slow and progressive course of right ventricular failure, as well as to recognize constrictive pericarditis as a cause of chronic ascites.The hemodynamic aspects of the disease are of paramount importance for early diagnosis and opportune treatment.

[Ogilvie syndrome. Report of two cases]

Acute colonic pseudo-obstruction or "Ogilvie syndrome (OS)," is a gastrointestinal motility disorder characterized by marked dilatation of the colon in the absence of mechanical obstruction. It occurs most commonly in the postoperative state or with severe medical illness; it has been associated with a wide range of comorbidities, including trauma, pelvic surgery (orthopedic, gynecologic, urologic), metabolic disorders, central nervous system disorders, and prostaglandin abnormalities. OS may also be drug induced or idiopathic. Left untreated, it can progress to perforation, peritonitis, and death. Definitive management of OS traditionally has consisted of mechanical decompression. However, neostigmine, an acetyl-cholinesterase inhibitor, has recently emerged as a safe and effective pharmacologic alternative in the adult population. We present two cases of OS attended in the intensive care unit treated with colonoscopy and cecostomy respectively.

[Cosyntropin test in severe active tuberculosis]

BACKGROUND

Frequency of adrenal insufficiency in patients with tuberculosis varies from 0 to 58%; however, all published series excluded severely ill patients. Our objective was to investigate adrenal insufficiency with the low-dose cosyntropin test in patients with severe active tuberculosis.

METHOD

From two large university affiliated hospitals, 18 patients with tuberculosis and criteria of sepsis or severe sepsis according to SCCM/ACCP criteria, defined by the present authors as severe active tuberculosis, participated in the study. A low-dose ACTH test with 10 mg of ACTH was performed. After ACTH test, all patients received a stress dose of hydrocortisone (240 mg/day) during their entire hospitalization along with four antituberculous drugs. Abnormal response was considered when elevation of serum cortisol was <7 microg/dl with respect to basal level, 60 min after ACTH administration.

RESULTS

Adrenal insufficiency was found in seven patients (39%); no clinical or laboratory data were associated with the presence of abnormal adrenal response. Except in one patient with HIV infection, all the signs and symptoms improved after antituberculous and hydrocortisone treatment. The increment in serum cortisol value post-ACTH test was lower in patients with hypoalbuminemia.

CONCLUSIONS

Adrenal insufficiency is frequent in severe active tuberculosis. The efficacy and security of supplemental steroid treatment in severe active tuberculosis should be established by a randomized clinical trial.

[Respiratory tract fluid microbiology in an intensive care unit]

OBJECTIVE

to know patterns of antimicrobial resistance of bacterial isolates from tracheal aspirates in an Intensive Care Unit and to evaluate the cases of ventilator-associated pneumonia.

METHODS

antibiotic sensitivity test was done. A comparison was made between patients with nosocomial pneumonia reported by infection surveillance team against those reported by the attending physician with the infectious disease consultant.

RESULTS

Pseudomonas aeruginosa was the bacteria most frequently reported with 134 isolates (26 %), 71 were multiple-drug-resistant; followed by Staphylococcus with 122 isolates (24 %), of which 88 were S. aureus with 62 of them (70 %) methicillin-resistant. Enterobacteriaceae, E. coli, K. pneumoniae, E. cloacae, S. marcescens, as well as Acinetobacter sp. and S. maltophilia were occasionally isolated. Candida represented 17 % of the isolates. Three peaks of isolates of S. aureus and P. aeruginosa were identified during the two years of surveillance. There were differences in cases of ventilator associated pneumonia reported by the hospital based epidemiology team and the attending clinicians in collaboration with an Infectious disease consultant.

CONCLUSIONS

prevalence of multiple-drug-resistant Pseudomonas aeruginosa (53 %) and methicillin resistant Staphylococcus (70 %) isolated from the airway is high in our Intensive Care Unit. Enterobacterias, Acinetobacter sp. and Stenotrophomonas maltophilia colonization are low in our Intensive Care Unit.

[Mean airway pressure during pressure-controlled ventilation with static vs. dynamic positive end-expiratory pressure]

BACKGROUND

Positive end-expiratory pressure increases mean airway pressure (Paw) in patients with mechanical ventilation. We undertook this study to compare mean airway pressure (Paw) generated with static PEEP (sPEEP) vs. dynamic PEEP (dPEEP) at the same level of total PEEP (tPEEP) in the same patient with pressure-controlled mechanical ventilation (PC).

METHODS

We conducted a prospective clinical trial at the Intensive Care Unit of a university-affiliated hospital. Consecutive patients in PC with SaO2>90%; FiO2<50%; sPEEP of 4 cm H2O and inspiration-expiration ratio (I:E ratio) 1:2 were included in the study. After a basal period of time of 15 min, Paw was registered (phase one of the study protocol). In phase 2 with the ventilator settings constant, only the I:E ratio was switched to 2:1 to generate dPEEP, and after 15 min Paw and total PEEP (tPEEP) were registered (tPEEP=sPEEP+dPEEP). In phase 3, the I:E ratio was switched back to 1:2 substituting the dPEEP generated in the second phase of the study by sPEEP to maintain the same level of tPEEP of phase 2. After 15 min, Paw was again registered. Friedman and Wilcoxon's test were used, p value<0.05 was considered statistically significant.

RESULTS

Thirty eight patients were admitted to the study protocol, tPEEP was 4, 8 and 8 cm H2O and median of the Paw 8.7, 13.8, and 11.4 cm H2O, respectively, with a p value<0.05 in the first, second and third phases of the study.

CONCLUSIONS

During pressure control ventilation, mean airway pressure is affected by the level of total PEEP and its composition. Paw is higher when dynamic PEEP participates in the composition of total PEEP.

[Hyperglycemia in critically ill patients: clinical implications for treatment]

Hyperglycemia is frequent during critical illness and is perceived by the clinician as part of the systemic metabolic response to stress. Of all patients with "stress hyperglycemia" only one third are known to have diabetes mellitus. Previous studies reported that patients presenting hyperglycemia during acute illness have an increased risk for nosocomial infections. Morbidity and mortality also increases in patients with myocardial infarction or stroke who develop hyperglycemia. Contemporary medical practice states that hyperglycemia under these conditions should only be treated with insulin if blood glucose levels are > 200 mg/dl. A recent trial showed that intensive insulin treatment of critically ill patients in the intensive care unit with the goal of maintaining blood glucose levels between 80 and 110 mg/dl significantly reduced morbidity and mortality without significant risk of hypoglycemia. These benefits of insulin treatment are not yet well understood, but some pathophysiological evidence suggests that hyperglycemia contributes to perpetuate the systemic proinflammatory response, and insulin--a natural endogenous hormone that has a major role in the intermediary metabolism--participates actively in the systemic anti-inflammatory response. As a result of these findings, we recommend that hyperglycemia during critical illness should be treated with insulin, in order to achieve blood glucose levels in a normal range, regardless of whether or not these patients have diabetes mellitus.

[Cerebral Blood flow velocity spectrum by transcranial doppler ultrasound in patients with brain death clinical criteria]

OBJECTIVE

To evaluate cerebral blood flow (CBF) direction, speed, and shape of Doppler profile in patients with clinical criteria of brain death (BD).

PATIENTS

A total of 42 consecutive patients with clinical criteria for BD were included.

MEASUREMENTS AND INTERVENTIONS

After anemia, hypothermia and hypocapnia were ruled out; confirmatory electroencephalogram (EEG) and a complete transcranial Doppler ultrasonography (TCDU) profile of circle of Willis and basilar arteries were done in all patients. Patients continued with mechanical ventilation and support in the Intensive Care Unit.

RESULTS

All EEG reported generalized theta and delta waves, which were associated with a TCDU profile showing small systolic peaks without diastolic wave. CBF velocities of < 10 cm/sec were recorded in all patients. Only four patients had reverberating flow. At follow-up, cardiac arrest occurred in all patients at a mean of 2 +/- 0.84 days.

CONCLUSIONS

Patients with clinical criteria of BD frequently have slow wave neuronal electrical activity on EEG that anticipates cardiac arrest. In these patients, TCDU detects an early and severe drop in CFB that is incompatible with life. TCDU should be done when other confirmatory tests like EEG suggest some retention of brain function.

[Plasmapheresis in Guillain-Barre syndrome]

OBJECTIVE

To evaluate the efficacy of early therapeutic plasmapheresis in severely affected patients with Guillain-Barré syndrome (GBS).

PATIENTS AND METHOD

Patients between 16 to 70 years of age, with GBS according to NINCDS criteria, in stage > or = 3 of Huges severity score and with less than 7 days of onset of symptoms were admitted for therapeutic plasmapheresis. All patients completed a total of five sessions of plasma exchange every other day using 25% albumin and saline in a 1:1 proportion. Follow-up was performed for 6 months. Friedman and Wilcoxon tests were done to establish differences within groups.

RESULTS

A total of 34 patients were admitted to the study. The time span between onset of symptoms and admission to the study was 4 days (median). Fourteen (41%) required mechanical ventilation. Clinical progression of the syndrome was observed during the first two sessions of plasma-pheresis. Improvement in motor function by Huges score was observed only after fourth session of plasma exchange (p < 0.05). Two patients did not improve, and one died.

CONCLUSIONS

Clinical improvement in GBS during early therapeutic plasmapheresis occurs only after the fourth session of plasma exchange.

[Clinical and epidemiological characteristics of severe poisoning in an adult population admitted to an intensive care unit]

OBJECTIVE

To describe the clinical and epidemiological features of severe acute poisonings in an adult population.

DESIGN

Retrospective analysis of clinical cases.

PATIENTS AND METHODS

Analysis of the clinical charts, risk factors and main outcomes of 55 acute poisoned patients admitted to an intensive care unit (ICU).

RESULTS

Of the 55 clinical charts reviewed, female prevailed over male gender with a relation of 1.5:1, the average age was 32 years (16-83 years), the major etiologic factor for the acute poisonings were drugs in 35 cases (64%), and home or work chemicals in 20 cases (36%). The mechanisms of intoxication/poisoning were: attempted or successful suicide in 51 cases (93%), accidental poisoning in three cases (5%), and iatrogenic in one case (2%). Precipitating factors were major depressive disorder in 29 cases (53%), dysthymic disorder in 12 cases (22%) and adjustment disorder with depressive mood or impulsive act in nine cases (16%). Associated feature comorbid conditions were: homosexuality, schizophrenia, drug addiction, AIDS, other chronic diseases, and previous suicide attempts. Outcomes were 33 (60%) patients discharged from the ICU without sequela, seven (13%) with permanent severe sequela and 15 (27%) deaths.

CONCLUSIONS

There was a high rate of suicides related with depressive disorders in a predominantly female population. Drug products were used more frequently than home or work chemicals. Although advanced life support and antidotal treatments were available, mortality was high. Areas where injury prevention efforts might have an influence on adult poisoning morbidity and mortality include management of depression as well suitable control of drugs and chemicals.

[Acute fatty liver of pregnancy complicated by pancreatitis]

A woman with acute fatty liver of pregnancy developed fulminant hepatic failure after delivery, a time when spontaneous recovery was expected. Pancreatitis and multiple organ failure was documented and intensive treatment in a critical care unit was needed to support organ function. She underwent plasmapheresis due to extreme hyperbilirubinemia and coma. She recovered completely.

[Acute non-calculous cholecystitis at a multidisciplinary intensive care unit]

OBJECTIVE

To describe three cases of acute acalculous cholecystitis (AAC) in critically ill patients.

PATIENTS AND METHODS

Admission charts of critically ill patients who required advanced life support in the intensive care unit and fulfilled three or more of the following ultrasonographic or tomographic diagnostic criteria for AAC were reviewed: 1. Gallbladder wall thickness > 4 mm with an increase in its volume (vesicular hydrops), 2. Pericholecystic fluid, 3. Subserosal edema, 4. Sloughing of the mucosa, 5. Abscence of calculi.

RESULTS

Three men that met the criteria for AAC were identified from a total of 490 admission charts. The median age was 49 years, the average APACHE II at admission was 17 points. The median time in the ICU before development of AAC was 24 days. All patients had leukocytosis. The three cases were resolved by percutaneous cholecystostomy and external biliary drainage.

CONCLUSIONS

The incidence of AAC in our ICU is one s case per 160 admissions or 0.6%. Shock, use of vasopressor drugs, narcotics and mechanical ventilation with PEEP are frequent in patients who subsequently develop AAC. Percutaneous cholecystostomy with external biliary drainage constitutes a safe and definitive treatment when there is no gangrene of the gallbladder wall.

Characterization of a possible uptake mechanism of selective antibacterial peptides

Selective antibacterial peptides containing less than 30 amino acid residues, cationic, with amphipathic properties, have been the subject of several studies due to their active participation and beneficial effects in strengthening the immune system of all living organisms. This manuscript reports the results of a comparison between the group of selective antibacterial peptides and another group called "cell penetrating peptides". An important number of the selective antibacterial peptides are cell penetrating peptides, suggesting that their toxicity is related to their uptake mechanism. The verification of this observation also includes the adaptation of a method previously published, called Polarity index, which reproduces and confirms the action of this new set of peptides. The efficiency of this method was verified based on four different databases, yielding a high score. The verification was based exclusively on the peptides already reported in the databases which have been experimentally verified.