Paedodontic preformed crowns in primary teeth and relative degree of dental wear.

AIM: Prosthetic rehabilitation of deciduous teeth in paediatric age using pre-formed crowns has been considered one of the best methods of dental restoration since their introduction. Their main advantages are related to durability, longevity and a low rate of recurrent cavities. Since stainless steel crowns do not coincide with aesthetic needs of parents and patients, preformed paedodontic crowns made of zirconia and nano-hybrid composite was introduced. The aim of the study is to evaluate the degree of wear on the enamel and on themselves of the different paedodontic crowns. MATERIALS: Nine bovine teeth and nine paedodontic crowns for deciduous molars were selected for the study, three of which in zirconia, three in nano-hybrid composite and three in stainless steel. Wear test was carried out on the Rtech™ Instruments tribometer applying a force of 50 N. After that, both the bovine teeth and the paedodontic crowns were observed using a stereo microscope (Zeiss Stemi C-500) and a scanning electron microscope (SEM, Cambridge Stereoscan 440). The areas of wear were calculated with a software [ImageJ, version 1x, Wayne Rasband, Maryland, USA]. CONCLUSION: Pre-formed paediatric crowns in zirconia, nano-hybrid composite and stainless steel are a valid aid for the restoration of deciduous teeth and do not compromise the physiological wear characteristic of the phases of the dental exchange. The stainless steel crown is preferable for the restorations in the posterior sectors as its behaviour is the most similar to that of a natural tooth. Zirconia and nano-hybrid composite crowns showed an inversely proportional behaviour between their wear volume and that of the opposing tooth.

On the corrosion, stress corrosion and cytocompatibility performances of ALD TiO2 and ZrO2 coated magnesium alloys.

Magnesium alloys are increasingly studied as materials for temporary implants. However, their high corrosion rate and susceptibility to corrosion-assisted cracking phenomena, such as stress corrosion cracking (SCC), continue to prevent their mainstream use. Recently, coatings have been considered to provide an effective solution to these issues and researchers have focused their attention on Atomic Layer Deposition (ALD). ALD stands out as a coating technology due to the outstanding film conformality and density achievable, and has shown encouraging preliminary results in terms of reduced corrosion rate and reduced SCC susceptibility. Here, we contribute to the ongoing interest in ALD-coated Mg alloys, providing a comprehensive characterisation of the effect of 100 nm thick ALD TiO2 and ZrO2 coatings on the corrosion behaviour and SCC susceptibility of AZ31 alloy. Moreover, we also investigate the effect of these coatings on the induced biological response. Our results suggest that the ALD coatings can improve the corrosion and SCC resistance of the Mg alloy, with the ZrO2 ALD coating showing the best improvements. We suggest that the different corrosion behaviours are the cause of the cytocompatibility results (only the ZrO2 ALD coating was found to meet the demands for cellular applications). Finally, we leverage on considerations about the coatings' wettability, electrochemical stability and surface integrity to justify the different results.

Enhancement of stress corrosion cracking of AZ31 magnesium alloy in simulated body fluid thanks to cryogenic machining.

Magnesium and its alloys have recently attracted great attention as potential materials for the manufacture of biodegradable implants. Unfortunately, their inadequate resistance to the simultaneous action of corrosion and mechanical stresses in the human body have hampered their use as implant materials. This work aims at evaluating the Stress Corrosion Cracking (SCC) susceptibility of the AZ31 Mg alloy after being machined under cryogenic cooling. The SCC behaviour was evaluated by means of Slow Strain Rate Tests (SSRTs) in Simulated Body Fluid (SBF) at 37 °C. Prior to testing, a full characterization of the machined surface integrity, including microstructural observations, residual stress, nano-hardness measurements and surface texture analysis was carried out together with the assessment of the corrosion properties through potentiodynamic polarization curves. In addition, the morphology of the fracture surfaces after SSRTs was analysed by means of 3D optical profiler and Scanning Electron Microscopy (SEM). The improved corrosion resistance due to the increased extension of the nano-surface layer and to the compressive residual stresses represents the reason of the reduced SCC susceptibility of cryogenically machined AZ31 samples as compared to dry machined ones.

Low concentrations of glyphosate-based herbicide cause complete loss of sperm motility of yellowtail tetra fish Astyanax lacustris.

Environmental relevant concentrations of glyphosate-based herbicide as 50 µg l-1 , 300 µg l-1 and 1800 µg l-1 can affect sperm quality of yellowtail tetra fish Astyanax lacustris. Viability of sperm cells was impaired at 300 µg l-1 , a concentration that is within legal limits in U.S.A. waterbodies, while motility was impaired at 50 µg l-1 , which is the more stringent limit set in Brazilian law. Therefore, environment protection agencies must review regulations of glyphosate-based herbicides on water bodies.

Conducta sexual en adolescentes varones: hacia un nuevo horizonte / Sexual behavior in male adolescents: towards a new horizon

La adolescencia implica un enfrentamiento por parte de los jóvenes a grandes cambios en el ámbito de la sexualidad, pudiendo esta etapa marcar su vida futura, especialmente al asociarse a conductas de riesgo. Los programas sanitarios del ámbito sexual en Chile están fundamentalmente dirigidos a mujeres, lo que junto a una tendencia natural masculina a asumir comportamientos de riesgo, ignorancia sobre su rol reproductivo, inicio sexual precoz y, en algunos casos, una orientación sexual diferente a la mayoría, vuelve a los hombres adolescentes especialmente vulnerables. Esto exige una preocupación por ellos, conociendo las tendencias actuales en su comportamiento y conducta sexual, y su compromiso con medidas de protección contra infecciones de transmisión sexual y anticoncepción, para luego ofrecer programas dirigidos a la población que los considere específicamente, en una atención sanitaria abierta, que les permita educarse. Así, eventualmente podremos disminuir las conductas de riesgo y la discriminación a la que muchos se ven enfrentados. En el presente artículo hacemos una revisión actualizada de algunos aspectos relevantes en relación a las vivencias sexuales de adolescentes varones chilenos y su contexto en el mundo, especialmente en Sudamérica, considerando: iniciación sexual, conductas sexuales, pareja estable, conductas de riesgo, conocimientos y actitudes en relación al virus de inmunodeficiencia humana, anticoncepción, y relaciones con el mismo sexo. Se discute finalmente el rol incompleto de la sociedad y de la Atención Primaria de Salud, en la acogida y educación para una sexualidad responsable, de los adolescentes varones de nuestro país.

Several important sexually related changes must be faced by adolescents, all of which may have influence in their future adult life, especially when they fall under risk behaviors. Chilean health programs in the field of sexuality are mainly aimed at women, which along with males' natural tendency to incur in risk behaviors, ignorance about their reproductive role, early sexual debut, and, in some cases, a different sexual orientation, make the adolescent male population especially vulnerable. This demands a particular care for male adolescents, recognizing the current features in their general and sexual behavior, and their commitment with protective measures against sexually transmitted infections and contraception. Therefore, it is necessary to offer educational programs aimed at the general population, which must include male adolescents. Thus, we will eventually reduce risk behaviors and discrimination affecting a significant portion of the adolescents. In this article, we review some of the most relevant features of sexual experiences of Chilean male adolescents - and their context in the world, especially in South America - considering: sexual debut, monogamy, risk behaviors, knowledge and attitudes in relation to human immunodeficiency virus, contraception, and homosexual relationships. We finally discuss the unsettled role of society and Primary Health Care System in the response to male adolescents in our country and their responsible sexual education.

Colon cancer adrenal metastasis: case report and review of the literature.

The authors report a case of alone right adrenal metastasis from colon carcinoma discovered incidentally by CT scan imaging 4 years after colon resection in a 74-year-old man. The presence of metastasis in the adrenal glands represents the second most frequent cause of "adrenal incidentaloma", following cortical-adrenal adenomas. The most common primary tumors responsible for adrenal metastasis are carcinoma of the lung, breast and kidney. Alone adrenal metastases due to colon or rectal carcinoma is very rare. Due to their rarity, at present there are not randomised studies supporting the effectiveness of surgery. Nevertheless, on the basis of international Literature and our experience of adrenalectomy could represent the current "gold-standard" therapeutic approach.

Additional femoral catheter in combination with popliteal catheter for analgesia after major ankle surgery.

BACKGROUND: The contribution of the saphenous nerve in pain after major ankle surgery is unknown. The aim of this study was to evaluate its contribution in this context. METHODS: Fifty patients were included in this prospective, randomized, controlled study. In all patients [Group P (popliteal) and Group F (popliteal+femoral)], a popliteal catheter was placed before operation and ropivacaine 0.5% (30 ml) administered via this catheter; major ankle surgery was then performed under spinal anaesthesia. In Group PF patients, an additional femoral catheter was sited before operation and ropivacaine 0.5% (10 ml) administered. Six hours after spinal anaesthesia (defined as T(0)), a continuous infusion of ropivacaine 0.3% (14 ml h(-1)) was started through the popliteal catheter until T(24). Then, the concentration was reduced to 0.2% until T(48). Patients in Group PF received continuous ropivacaine 0.2% (5 ml h(-1)) through the femoral catheter from T(0) to T(48). I.V. morphine patient-controlled analgesia was used as a rescue analgesia. Pain at rest, pain with movement, adverse effects, and i.v. morphine consumption were assessed. Pain at rest and on movement was evaluated 6 months after operation. RESULTS: Pain at rest was comparable in the two groups. In Group PF, patients had significantly reduced pain during movement in the postoperative period (P=0.01) and 6 months after operation (P=0.03). Morphine consumption was significantly reduced in Group PF at T(0)-T(24) and T(24)-T(48) (P=0.01). Adverse effects were comparable in both groups. CONCLUSIONS: The addition of continuous femoral catheter infusion of ropivacaine to a continuous popliteal catheter infusion improved postoperative analgesia during movement after major ankle surgery. This effect was still present 6 months after surgery.

[Ultraconservative treatment in stage I and II breast carcinoma. Results of a long-term follow-up on 500 operated breasts]. / Trattamento ultraconservativo nel carcinoma della mammella in stadio I e II. Risultati di un follow-up a lungo termine su 500 mammelle operate.

AIM: Several randomized trials on conservative surgery compared with mastectomy in early-stage breast cancer have validated this technique in terms of local and distant relapse and survival of patients. Standard conservative approach includes surgical removal of the cancer with adequate cancer-free margins, axillary dissection, postoperative breast irradiation and adjuvant treatments when required. METHODS: From 1987 to 2003, 500 early stage breast carcinoma were treated on 494 patients with conservative surgery and postoperative radiotherapy. Surgery consisted in a wide tumorectomy, with intraoperative control of R0 margins. The total postoperative radiation dosage was 50 Gy on the whole breast, associated with a boost of 10 Gy on tumor bed (20 Gy in T2 neoplasms). Before 1997 node-positive patients were treated with axillary irradiation with 50 Gy. Postoperative chemotherapy and/or hormonal therapy were administered to patients according with node-involvement, age and menopausal status. AJCC-stage was T1N0 in 44%, T2N0 in 15%, T1N1 in 19% and T2N1 in 22% of the patients. RESULTS: In a postoperative setting, we observed 9% of axillary seromas or hematomas and 7% of oedema of the arm. At a median follow-up of 150 months (range 48-248 months), actuarial local recurrence rates were 7% at 5 years and 14% at 10 years. The actuarial rates of distant metastases were 18% at 5 years and 33% at 10 years. Ten-year overall and disease-free survival rates were 81% and 60%, respectively. Cosmetic results were good/excellent in 80%, satisfactory in 10% and poor in 10% of patients. CONCLUSION: Recurrence and survival rates in breast-conserving surgery are consistent with indexed literature on conservative treatment of early breast cancer. Women eligible for conservative treatment should be offered the choice of either wide tumorectomy or quadrantectomy with axillary lymph nodes removal and postoperative radiotherapy, or modified radical mastectomy.

[Cystic pancreatic tumors. Review of literature and proposal of a diagnostic-therapeutic pathway]. / I tumori cistici del pancreas. Revisione della letteratura e proposta di un percorso diagnostico-terapeutico.

In this paper the Authors consider the epidemiological, clinical, pathological, instrumental, chemical and physical findings of every type of pancreatic cystic lesions. They perform a critical examination of each of them. In this way, they can identify the most important features of every single class. A pathway consisting in four main groups of instrumental and chemical tests (abdominal ultrasonography / EUS, CT, MR, FNA / biopsy/ assay of tumoral markers and amylase of cystic fluid) was chosen to know all these informations according to careful principles of specificity, sensitivity and diagnostic accuracy taken from international scientific literature. In each subgroup of cystic pancreatic tumor, at last, the most reliable therapeutic project is suggested according to the common international scientific agreement.

Synthesis of aminoglycoside-modified oligonucleotides.

[structure: see text] To study the structural requirements of aminoglycoside binding to nucleic acids, compound 1-an analogue of the naturally occurring nucleoside J-was synthesized. When incorporated into oligodeoxynucleotides, 1 leads to thermal stabilization of the resulting duplexes. The increase in pairing affinity is stronger with complementary RNA than with DNA.

Effects of ventilator resetting on indirect calorimetry measurement in the critically ill surgical patient.

OBJECTIVE: To evaluate the effect of acute changes in minute ventilation (VE) on oxygen consumption (VO2), carbon dioxide production (VCO2), respiratory quotient, and energy expenditure during volume-controlled mechanical ventilation in the critically ill surgical patient. The effects on some oxygen transport variables were assessed as well. DESIGN: Prospective, randomized clinical study SETTING: Adult surgical intensive care unit of a university teaching hospital. PATIENTS: Twenty adult critically ill surgical patients were studied during volume-controlled mechanical ventilation. INTERVENTIONS: After a basal period of stability (no changes over time in body temperature, energy expenditure, blood gases, acid-base status, cardiac output, and ventilatory parameters), VE was then randomly either increased or reduced (+/-35%) by a change in tidal volume (VT), while respiratory rate and inspiratory/expiratory ratio were kept constant. Settings were then maintained for 120 mins. During the study, patients were sedated and paralyzed. MEASUREMENTS AND MAIN RESULTS: VO2, VCO2, and respiratory quotient were measured continuously by a Nellcor Puritan Bennett 7250 metabolic monitor (Nellcor Puritan Bennett, Carlsbad, CA). Hemodynamic and oxygen transport parameters were obtained every 15 mins during the study. Despite large changes in VE, VO2 and energy expenditure did not change significantly either in the increased or in the reduced VE groups. After 15 mins, VCO2 and respiratory quotient changed significantly after ventilator resetting. VCO2 increased by 10.5 +/- 1.1% (from 2.5 +/- 0.10 to 2.8 +/- 0.12 mL/min/kg, p< .01) in the increased VE group and decreased by 12.4 +/- 2.1% (from 2.7 +/- 0.17 to 2.4 +/- 0.16 mL/min/kg, p< .01) in the reduced VE group. Similarly, respiratory quotient increased by 16.2% +/- 2.2% (from 0.87 +/- 0.02 to 1.02 +/- 0.02, p< .01) and decreased by 17.2% +/- 1.8% (from 0.88 +/- 0.02 to 0.73 +/- 0.02, p< .01). VCO2 normalized in the reduced VE group, but remained higher than baseline in the increased VE group. Respiratory quotient did not normalize in both groups and remained significantly different from baseline at the end of the study. Cardiac index, oxygen delivery, and mixed venous oxygen saturation increased, while oxygen extraction index decreased significantly in the reduced VE group. Neither of the mentioned parameters changed significantly in the increased VE group. CONCLUSIONS: We conclude that, during controlled mechanical ventilation, the time course and the magnitude of the effect on gas exchange and energy expenditure measurements caused by acute changes in VE suggest that VO2 and energy expenditure measurements can be used reliably to evaluate and quantify metabolic events and that VCO2 and respiratory quotient measurements are useless for metabolic purposes at least for 120 mins after ventilator resetting.

Calculated and measured oxygen consumption in mechanically ventilated surgical patients in the early post-operative period.

Oxygen consumption (VO2) measured by indirect calorimetry (Nellcor-Puritan-Bennett 7250; Carlsbad, CA, USA) has been compared with VO2 calculated by the Fick method in 22 volume-controlled ventilated general surgical patients in the early post-operative period. For 198 pairs of measurements, VO2 Fick and VO2 indirect calorimetry correlated significantly (y = 1.00x - 35.8, P = 0.0001, r = 0.77). VO2 indirect calorimetry was 212 +/- 32 mL min-1 and VO2 Fick was 177 +/- 41 mL min-1 (P = 0.0001). The bias was 35 +/- 26 mL min-1. This difference represents 16 +/- 13% of the total body VO2. VO2 calculated by the Fick method did not accurately predict VO2 measured by indirect calorimetry, and the two methods were not interchangeable. VO2 calculated by the Fick method underestimated VO2 as measured by indirect calorimetry by a systematic quantity that could be attributed, in part, to VO2 of the lung. Indirect calorimetry should be the preferred method for measuring total body VO2 in mechanically ventilated surgical patients.

Longstanding endobronchial foreign body.

There are many circumstances in which the diagnosis of endobronchial inhalation of a foreign body (FB) can be missed. Generally, in such cases, within weeks or at most months from the event, clinical bronchopulmonary symptoms develop which allow a correct diagnosis to be made and significant complications to be avoided. We report the case of a patient in whom an endobronchial FB remained undiagnosed, because of lack of symptoms, for almost three years, and then caused signifiicant complications before being identified and removed. Problems related to diagnosis and therapy are discussed.

Energy expenditure and severity of injury and illness indices in multiple trauma patients.

OBJECTIVE: To determine whether the energy expenditure of mechanically ventilated multiple trauma patients correlates with the severity of injury and illness indices before important systemic infection has complicated the clinical course, and to compare the energy expenditure with the energy expenditure expected from the Harris-Benedict equation adjusted with correction factors for trauma. DESIGN: Prospective, clinical study. SETTING: General intensive care unit of a university teaching hospital. PATIENTS: Immediate multiple trauma adult patients who required mechanical ventilation. INTERVENTIONS: Metabolic cart connected to the ventilator. MEASUREMENTS AND MAIN RESULTS: Data on admission to the emergency department and during the first 24 hrs of intensive care unit admission were collected for computation of severity of injury and illness indices, respectively. Resting and total energy expenditures were derived at least 48 hrs after intensive care unit admission by continuous indirect calorimetry. Predicted basal energy expenditure was obtained using the Harris-Benedict equation and predicted total energy expenditure was calculated using the Harris-Benedict value adjusted with correction factors for trauma. Twenty-six multiple trauma adult patients completed the study. No statistically significant correlations were observed between both the resting energy expenditure and the total energy expenditure and the Injury Severity Score, Revised Trauma Score, Simplified Acute Physiologic Score II, Acute Physiology and Chronic Health Evaluation II score, and Glasgow Coma Scale score. A regression model of total energy expenditure was developed with the following variables: Harris-Benedict equation, heart rate, and minute ventilation (p = .01; r2 = .74). The resting energy expenditure/predicted basal energy expenditure ratio was 1.17+/-0.2 and the total energy expenditure/predicted total energy expenditure ratio was 0.76+/-0.1. CONCLUSIONS: In mechanically ventilated multiple trauma patients the energy expenditure is not correlated to the severity of injury and illness indices but is dependent on the Harris-Benedict equation in addition to heart rate and minute ventilation. Furthermore, this patient population is characterized by a moderate state of hypermetabolism, and the Harris-Benedict prediction modified with correction factors for trauma systematically overestimates the total energy expenditure.

[A strangulated perineal hernia. A rare case of intestinal obstruction]. / Ernia perineale strozzata. Un raro caso di occlusione intestinale.

A rare case of intestinal obstruction due to strangulated perineal hernia, observed among 533 small bowel obstructions operated since January 1982 until December 1994 (0.2%) is described. Less than 100 cases are reported in literature. The etiologic, anatomical and clinical aspects of perineal hernia are examined. The reported case is of the primitive, congenital type caused by defect of the rectovaginal fascia fusion, in correspondence of the Douglas. Preoperative diagnosis is very difficult. Strangulation of this type of hernia is rare, the hernial sac surrounding tissue being elastic. In case of strangulation, symptoms of intestinal obstruction appear. In the reported case the preoperative diagnosis was "acute abdomen", because there was defence in hypogastrium and in the right iliac fossa. A straight abdominal radiography has not been performed. In the reported case the patient, a 22-year-old woman, was promptly operated and the incarcerated intestinal loop released. A regular postoperative period followed. The importance of a complete clinical examination, of a straight abdominal radiography and of a promptly performed operation is underlined.

Comparison between cardiac output measured by thermodilution technique and calculated by O2 and modified CO2 Fick methods using a new metabolic monitor.

OBJECTIVE: To calculate cardiac ouptut from dual oximetry with carbon dioxide production (VCO2) and oxygen consumption (VO2) measured by a new metabolic monitor, and to compare these values with measurements made simultaneously using the thermodilution method during the steady state condition. DESIGN: Prospective, comparative clinical study. SETTING: The adult postsurgical intensive care unit (ICU) of a University Hospital. PATIENTS: Twenty mechanically ventilated postsurgical patients (70.7 +/- 7.8 years of age; range 50-84). MEASUREMENTS AND RESULTS: A new metabolic monitor (Puritan-Bennett 7250, Carlsbard, USA) connected to a ventilator (Puritan-Bennett 7200) was used to measure VCO2 and VO2. Measurements of arterial (SaO2) and mixed venous (SvO2) oxygen saturations were made using pulse and venous fiberoptic oximeters. Cardiac output starting from VCO2 (COVCO2) was obtained according to Mahutte's formula: COVCO2 = VCO2/[k (SaO2-SvO2)], where k represents a constant. The value for each patient was determined from the initial measurements of thermodilution cardiac output (COtd), VCO2, SaO2 and SvO2. COVCO2 calculated from the previous equation was compared to the COtd. Cardiac output calculated from the traditional O2 Fick equation (COVO2) was compared to the COtd. All patients were studied over a period of 120 min at 15-min intervals in reasonably stable conditions. COVCO2 was closely related to COtd (r = 0.94; SEE = 0.79; p = 0.0001; n = 180) with a bias of -0.10 and a precision of 0.45 l/min. The mean percent difference between the two methods was -2.2 +/- 8.3%. COVO2 was related to COtd (r = 0.77; SEE = 0.79; p = 0.0001; n = 180) with a bias of -0.57 and precision of 0.86 l/min. The mean percent difference between the two methods was -10.8 +/- 16.0%. CONCLUSIONS: In stable patients, cardiac output measurements obtained from dual oximetry with VO2 and VCO2 measured by this new metabolic monitor, show good correlation with measurements made using the thermodilution method. The values of cardiac output calculated from VCO2 are more accurate and precise than values from VO2. The validity of these measurements in hemodynamically unstable patients and during various modes of mechanical ventilation seems warranted.

[Intestinal obstruction caused by paracecal hernia. 3 case reports and review of the literature]. / Occlusione intestinale da ernia paracecale. Descrizione di tre casi e revisione della letteratura.

The authors report three rare cases of intestinal obstruction due to paracecal hernia observed in 533 small bowel obstructions operated between January 1982 and December 1994 (0.6%). In our experience, all the cases occurred in old female patients. Less than 150 cases are reported in the literature. The authors examine paracecal hernia embryologic aspects to explain its pathogenesis: the rotation of primary intestinal loop determines final intestinal rapports. Preoperative diagnosis is very difficult. Transitory symptoms may appear months or years before intestinal obstruction; these occurrences suggest that internal hernias, like external ones, may spontaneously reduce. Straight abdominal radiographies, performed in all cases here described, demonstrate small bowel levels. There is disproportion between important subjective symptoms and objective finding of a large round bump localized in the right iliac fossa. Authors underline the opportunity of a promptly performed operation: in all our cases we released the incarcerated intestinal loops and sutured hernial foramen. One exitus occurred, on the 4th postoperative day, probably due to pulmonary embolism.

Indirect calorimetry in critically ill patients: clinical applications and practical advice.

Indirect calorimetry is the method by which metabolic rate and substrate utilization are estimated in human beings starting from respiratory gas exchange measurements and urinary nitrogen excretion. This method is based on some models and assumptions that must be known and taken into consideration to correctly interpret the results obtained. Recent advances in technology and the availability of precise and portable metabolic carts have made this technique practical at the beside even in critically ill patients. It must be considered that, particularly in the ICU, there may be several sources of error and many technical difficulties in applying this methodology. Taking into account the relevant clinical studies related to the outcomes of critically ill patient, this article defines when the assessment of energy expenditure by indirect calorimetry may provide useful and valid information. Review of the literature suggests that the clinical application of indirect calorimetry in critically ill patients, although promising, requires further evaluation. Currently, the potential useful clinical applications of indirect calorimetry in this category of patients can be summarized as follows: (1) assessment of energy expenditure in patients who fail to adequately respond to the estimated nutritional needs; (2) assessment of energy expenditure in patients with single- or multiple-organ dysfunction who need prolonged ICU care and artificial nutritional support; (3) assessment of the effects induced by artificial nutrition on the cardiocirculatory and respiratory systems in mechanically ventilated patients with acute respiratory failure; and (4) monitoring of VO2 during weaning from mechanical ventilation.