An approach to aircraft seat comfort using interface pressure mapping

The objective of the present study is to propose a method to dynamically evaluate discomfort of a passenger seat by measuring the interface pressure between the occupant and the seat during the performance of the most common activities of a typical flight(1). This article reports the results of resting and reading studies performed in a simulator that represents the interior of a commercial aircraft.

Influence of different types of seat cushions on the static sitting posture in individuals with spinal cord injury

Study design: Cross-sectional study. Objectives: To evaluate the efficacy of the Postural Assessment Software PAS/SAPO in the posture analysis of individuals with spinal cord injury (SCI) during sitting position and to analyze if the use of different types of seat cushions-gel and foam, with no cushion-can interfere in the individual's posture during sitting position. Setting: Centre of Rehabilitation at the University Hospital (FMRP-USP), Ribeirao Preto, Brazil. Methods: Eight individuals, four paraplegics and four tetraplegics with SCI and 20 healthy individuals participated in the study. Photos were taken of individuals in the sitting position using foam, gel cushions and with no cushion. They were analyzed using the PAS/SAPO. The alignment of the anterior-superior iliac spine (ASIS) and the posterior pelvic tilt were evaluated from the angle formed between the ASIS and the greater trochanter of the femur. Results: The group of healthy individuals presented the best postural alignment when compared with the group with SCI, both for the ASIS alignment (P < 0.05) and for the degree of posterior pelvic tilt (P < 0.05). No significant differences were found in the variables analyzed when the seat cushions were compared. Conclusion: The different types of cushions did not alter the sitting posture; however, individuals with SCI showed worse postural alignment than the healthy individuals. PAS/SAPO was demonstrated to be useful for postural assessment. Spinal Cord (2012) 50, 627-631; doi:10.1038/sc.2012.7; published online 21 February 2012

PEEP-ZEEP technique: cardiorespiratory repercussions in mechanically ventilated patients submitted to a coronary artery bypass graft surgery

Abstract Background The PEEP-ZEEP technique is previously described as a lung inflation through a positive pressure enhancement at the end of expiration (PEEP), followed by rapid lung deflation with an abrupt reduction in the PEEP to 0 cmH2O (ZEEP), associated to a manual bilateral thoracic compression. Aim To analyze PEEP-ZEEP technique's repercussions on the cardio-respiratory system in immediate postoperative artery graft bypass patients. Methods 15 patients submitted to a coronary artery bypass graft surgery (CABG) were enrolled prospectively, before, 10 minutes and 30 minutes after the technique. Patients were curarized, intubated, and mechanically ventilated. To perform PEEP-ZEEP technique, saline solution was instilled into their orotracheal tube than the patient was reconnected to the ventilator. Afterwards, the PEEP was increased to 15 cmH2O throughout 5 ventilatory cycles and than the PEEP was rapidly reduced to 0 cmH2O along with manual bilateral thoracic compression. At the end of the procedure, tracheal suction was accomplished. Results The inspiratory peak and plateau pressures increased during the procedure (p < 0.001) compared with other pressures during the assessment periods; however, they were within lung safe limits. The expiratory flow before the procedure were 33 ± 7.87 L/min, increasing significantly during the procedure to 60 ± 6.54 L/min (p < 0.001), diminishing to 35 ± 8.17 L/min at 10 minutes and to 36 ± 8.48 L/min at 30 minutes. Hemodynamic and oxygenation variables were not altered. Conclusion The PEEP-ZEEP technique seems to be safe, without alterations on hemodynamic variables, produces elevated expiratory flow and seems to be an alternative technique for the removal of bronchial secretions in patients submitted to a CABG.

The use of thermal manikin to evaluate interface pressure distribution

The use of a thermal buttocks manikin(1) was explored as a tool to standardize the evaluation of seat comfort. Thermal manikin buttocks were developed and calibrated thermally and anatomically to simulate the sensible heat transfer of a seated person and used to evaluate interface pressure distribution. In essence, the pressure maps of manikin buttocks with and without heating were compared to those of a seated person. The results of average pressure demonstrated that the thermal manikins have a better response in interface pressure measurement than manikins without heating.

Predicting epidemic outbreak from individual features of the spreaders

Knowing which individuals can be more efficient in spreading a pathogen throughout a determinate environment is a fundamental question in disease control. Indeed, over recent years the spread of epidemic diseases and its relationship with the topology of the involved system have been a recurrent topic in complex network theory, taking into account both network models and real-world data. In this paper we explore possible correlations between the heterogeneous spread of an epidemic disease governed by the susceptible-infected-recovered (SIR) model, and several attributes of the originating vertices, considering Erdos-Renyi (ER), Barabasi-Albert (BA) and random geometric graphs (RGG), as well as a real case study, the US air transportation network, which comprises the 500 busiest airports in the US along with inter-connections. Initially, the heterogeneity of the spreading is achieved by considering the RGG networks, in which we analytically derive an expression for the distribution of the spreading rates among the established contacts, by assuming that such rates decay exponentially with the distance that separates the individuals. Such a distribution is also considered for the ER and BA models, where we observe topological effects on the correlations. In the case of the airport network, the spreading rates are empirically defined, assumed to be directly proportional to the seat availability. Among both the theoretical and real networks considered, we observe a high correlation between the total epidemic prevalence and the degree, as well as the strength and the accessibility of the epidemic sources. For attributes such as the betweenness centrality and the k-shell index, however, the correlation depends on the topology considered.

Replacement of fentanyl infusion by enteral methadone decreases the weaning time from mechanical ventilation: a randomized controlled trial

Introduction: Patients undergoing mechanical ventilation (MV) are frequently administered prolonged and/or high doses of opioids which when removed can cause a withdrawal syndrome and difficulty in weaning from MV. We tested the hypothesis that the introduction of enteral methadone during weaning from sedation and analgesia in critically ill adult patients on MV would decrease the weaning time from MV. Methods: A double-blind randomized controlled trial was conducted in the adult intensive care units (ICUs) of four general hospitals in Brazil. The 75 patients, who met the criteria for weaning from MV and had been using fentanyl for more than five consecutive days, were randomized to the methadone (MG) or control group (CG). Within the first 24 hours after study enrollment, both groups received 80% of the original dose of fentanyl, the MG received enteral methadone and the CG received an enteral placebo. After the first 24 hours, the MG received an intravenous (IV) saline solution (placebo), while the CG received IV fentanyl. For both groups, the IV solution was reduced by 20% every 24 hours. The groups were compared by evaluating the MV weaning time and the duration of MV, as well as the ICU stay and the hospital stay. Results: Of the 75 patients randomized, seven were excluded and 68 were analyzed: 37 from the MG and 31 from the CG. There was a higher probability of early extubation in the MG, but the difference was not significant (hazard ratio: 1.52 (95% confidence interval (CI) 0.87 to 2.64; P = 0.11). The probability of successful weaning by the fifth day was significantly higher in the MG (hazard ratio: 2.64 (95% CI: 1.22 to 5.69; P < 0.02). Among the 54 patients who were successfully weaned (29 from the MG and 25 from the CG), the MV weaning time was significantly lower in the MG (hazard ratio: 2.06; 95% CI 1.17 to 3.63; P < 0.004). Conclusions: The introduction of enteral methadone during weaning from sedation and analgesia in mechanically ventilated patients resulted in a decrease in the weaning time from MV.

Use of pulse pressure variation to estimate changes in preload during experimental acute normovolemic hemodilution

Background. Acute normovolemic hemodilution (ANH) is an alternative to blood transfusion in surgeries involving blood loss. This experimental study was designed to evaluate whether pulse pressure variation (PPV) would be an adequate tool for monitoring changes in preload during ANH, as assessed by transesophageal echocardiography. Methods. Twenty-one anesthetized and mechanically ventilated pigs were randomized into three groups: CTL (control), HES (hemodilution with 6% hydroxyethyl starch at a 1:1 ratio) or NS (hemodilution with saline 0.9% at a 3:1 ratio). Hemodilution was performed in animals of groups NS and HES in two stages, with target hematocrits 22% and 15%, achieved at 30-minute intervals. After two hours, 50% of the blood volume withdrawn was transfused and animals were monitored for another hour. Statistical analysis was based on ANOVA for repeated measures followed by multiple comparison test (P<0.05). Pearson's correlations were performed between changes in left ventricular end-diastolic volume (LVEDV) and PPV, central venous pressure (CVP) and pulmonary artery occlusion pressure (PAOP). Results. Group NS received a significantly greater amount of fluids during ANH (NS, 900 +/- 168 mL vs. HES, 200 +/- 50 mL, P<0.05) and presented greater urine output (NS, 2643 +/- 1097mL vs. HES, 641 +/- 338mL, P<0.001). Significant decreases in LVEDV were observed in group NS from completion of ANH until transfusion. In group HES, only increases in LVEDV were observed, at the end of ANH and at transfusion. Such changes in LVEDV (Delta LVEDV) were better reflected by changes in PPV (Delta PPV, R=-0.62) than changes in CVP (Delta CVP R=0.32) or in PAOP (Delta PAOP, R=0.42, respectively). Conclusion. Changes in preload during ANH were detected by changes in PPV. Delta PPV was superior to Delta PAOP and Delta CVP to this end. (Minerva Anestesiol 2012;78:426-33)

Do children with motor difficulties show low levels of physical fitness?

The aim of the present study was to examine whether children with motor difficulties would show levels of health-related components of physical fitness lower than children without such difficulties. Sixteen children with motor difficulties with approximately 8 years of age were age-and gender-matched with other 16 children without motor difficulties. Participants completed the test batteries for physical fitness (seat and reach, standing long jump, sit-up, modified pull-up and 9-minute run) and for motor coordination (MABC-2). The results indicated significant differences in standing long jump, sit-up, modified pull-up tests, but not for the seat and reach and the 9-minute run tests. Overall, the results are similar to those published in the international literature, with the exception of cardiorespiratory fitness. The idea that at to some degree coordination is required to perform physical fitness tasks and might impact on physical fitness performance is further discussed in the present work.

Effects of different tidal volumes in pulmonary and extrapulmonary lung injury with or without intraabdominal hypertension

We hypothesized that: (1) intraabdominal hypertension increases pulmonary inflammatory and fibrogenic responses in acute lung injury (ALI); (2) in the presence of intraabdominal hypertension, higher tidal volume reduces lung damage in extrapulmonary ALI, but not in pulmonary ALI. Wistar rats were randomly allocated to receive Escherichia coli lipopolysaccharide intratracheally (pulmonary ALI) or intraperitoneally (extrapulmonary ALI). After 24 h, animals were randomized into subgroups without or with intraabdominal hypertension (15 mmHg) and ventilated with positive end expiratory pressure = 5 cmH(2)O and tidal volume of 6 or 10 ml/kg during 1 h. Lung and chest wall mechanics, arterial blood gases, lung and distal organ histology, and interleukin (IL)-1 beta, IL-6, caspase-3 and type III procollagen (PCIII) mRNA expressions in lung tissue were analyzed. With intraabdominal hypertension, (1) chest-wall static elastance increased, and PCIII, IL-1 beta, IL-6, and caspase-3 expressions were more pronounced than in animals with normal intraabdominal pressure in both ALI groups; (2) in extrapulmonary ALI, higher tidal volume was associated with decreased atelectasis, and lower IL-6 and caspase-3 expressions; (3) in pulmonary ALI, higher tidal volume led to higher IL-6 expression; and (4) in pulmonary ALI, liver, kidney, and villi cell apoptosis was increased, but not affected by tidal volume. Intraabdominal hypertension increased inflammation and fibrogenesis in the lung independent of ALI etiology. In extrapulmonary ALI associated with intraabdominal hypertension, higher tidal volume improved lung morphometry with lower inflammation in lung tissue. Conversely, in pulmonary ALI associated with intraabdominal hypertension, higher tidal volume increased IL-6 expression.

Comparison of lung preservation solutions in human lungs using an ex vivo lung perfusion experimental model

OBJECTIVE: Experimental studies on lung preservation have always been performed using animal models. We present ex vivo lung perfusion as a new model for the study of lung preservation. Using human lungs instead of animal models may bring the results of experimental studies closer to what could be expected in clinical practice. METHOD: Brain-dead donors whose lungs had been declined by transplantation teams were used. The cases were randomized into two groups. In Group 1, Perfadex (R) was used for pulmonary preservation, and in Group 2, LPDnac, a solution manufactured in Brazil, was used. An ex vivo lung perfusion system was used, and the lungs were ventilated and perfused after 10 hours of cold ischemia. The extent of ischemic-reperfusion injury was measured using functional and histological parameters. RESULTS: After reperfusion, the mean oxygenation capacity was 405.3 mmHg in Group 1 and 406.0 mmHg in Group 2 (p=0.98). The mean pulmonary vascular resistance values were 697.6 and 378.3 dyn.s.cm(-5), respectively (p=0.035). The mean pulmonary compliance was 46.8 cm H2O in Group 1 and 49.3 ml/cm H2O in Group 2 (p=0.816). The mean wet/dry weight ratios were 2.06 and 2.02, respectively (p=0.87). The mean Lung Injury Scores for the biopsy performed after reperfusion were 4.37 and 4.37 in Groups 1 and 2, respectively (p=1.0), and the apoptotic cell counts were 118.75/mm(2) and 137.50/mm(2), respectively (p=0.71). CONCLUSION: The locally produced preservation solution proved to be as good as Perfadex (R). The clinical use of LPDnac may reduce costs in our centers. Therefore, it is important to develop new models to study lung preservation.

Effect of treatment delay on disease severity and need for resuscitation in porcine fecal peritonitis

Objective: Early treatment in sepsis may improve outcome. The aim of this study was to evaluate how the delay in starting resuscitation influences the severity of sepsis and the treatment needed to achieve hemodynamic stability. Design: Prospective, randomized, controlled experimental study. Setting: Experimental laboratory in a university hospital. Subjects: Thirty-two anesthetized and mechanically ventilated pigs. Interventions: Pigs were randomly assigned (n = 8 per group) to a nonseptic control group or one of three groups in which fecal peritonitis (peritoneal instillation of 2 g/kg autologous feces) was induced, and a 48-hr period of protocolized resuscitation started 6 (Delta T-6 hrs), 12 (Delta T-12 hrs), or 24 (Delta T-24 hrs) hrs later. The aim of this study was to evaluate the impact of delays in resuscitation on disease severity, need for resuscitation, and the development of sepsis-associated organ and mitochondrial dysfunction. Measurements and Main Results: Any delay in starting resuscitation was associated with progressive signs of hypovolemia and increased plasma levels of interleukin-6 and tumor necrosis factor-alpha prior to resuscitation. Delaying resuscitation increased cumulative net fluid balances (2.1 +/- 0.5 mL/kg/hr, 2.8 +/- 0.7 mL/kg/hr, and 3.2 +/- 1.5 mL/kg/hr, respectively, for groups.T-6 hrs, Delta T-12 hrs, and.T-24 hrs; p < .01) and norepinephrine requirements during the 48-hr resuscitation protocol (0.02 +/- 0.04 mu g/kg/min, 0.06 +/- 0.09 mu g/kg/min, and 0.13 +/- 0.15 mu g/kg/min; p = .059), decreased maximal brain mitochondrial complex II respiration (p = .048), and tended to increase mortality (p = .08). Muscle tissue adenosine triphosphate decreased in all groups (p < .01), with lowest values at the end in groups Delta T-12 hrs and.T-24 hrs. Conclusions: Increasing the delay between sepsis initiation and resuscitation increases disease severity, need for resuscitation, and sepsis-associated brain mitochondrial dysfunction. Our results support the concept of a critical window of opportunity in sepsis resuscitation. (Crit Care Med 2012; 40:2841-2849)

Interference of different types of seats on postural control system during a forward-reaching task in individuals with paraplegia

We aimed to evaluate the influence of different types of wheelchair seats on paraplegic individuals' postural control using a maximum anterior reaching test. Balance evaluations during 50, 75, and 90% of each individual's maximum reach in the forward direction using two different cushions on seat (one foam and one gel) and a no-cushion condition were carried out on 11 individuals with a spinal cord injury (SCI) and six individuals without SCI. Trunk anterior displacement and the time spent to perform the test were assessed. No differences were found for the three types of seats in terms of trunk anterior displacement and the time spent to perform the test when intragroup comparisons were made in both groups (P > 0.05). The intergroup comparison showed that body displacement was less prominent and the time spent to perform the test was more prolonged for individuals with SCI (P < 0.05), which suggests a postural control deficit. The seat type did not affect the ability of the postural control system to maintain balance during the forward-reaching task.

Influence of brain death and associated trauma on solid organ histological characteristics

PURPOSE: To evaluate histopathological alterations triggered by brain death and associated trauma on different solid organs in rats. METHODS: Male Wistar rats (n=37) were anesthetized with isoflurane, intubated and mechanically ventilated. A trepanation was performed and a balloon catheter inserted into intracraninal cavity and rapidly inflated with saline to induce brain death. After induction, rats were monitored for 30, 180, and 360 min for hemodynamic parameters and exsanguinated from abdominal aorta. Heart, lung, liver, and kidney were removed and fixed in paraffin to evaluation of histological alterations (H&E). Sham-operated rats were trepanned only and used as control group. RESULTS: Brain dead rats showed a hemodynamic instability with hypertensive episode in the first minute after the induction followed by hypotension for approximately 1 h. Histological analyses showed that brain death induces vascular congestion in heart (p<0.05), and lung (p<0.05); lung alveolar edema (p=0.001), kidney tubular edema (p<0.05); and leukocyte infiltration in liver (p<0.05). CONCLUSIONS: Brain death induces hemodynamic instability associated with vascular changes in solid organs and compromises most severely the lungs. However, brain death associated trauma triggers important pathophysiological alterations in these organs.

Physical properties of edible films based on bovine myofibril proteins

Myofibril proteins have excellent filmogenic properties. The objective of this article was to study the effect of the thermal treatment, of the pH and of the plasticizer concentration (Cp) of the filmogenic solution (FS), using over some physical properties of edible films, using a surface and response methodology (SRM). Films were made of lyophilized myofibril proteins (LMP) extracted from bovine muscle, employing the technique of solubility obtained from diluted saline solutions. The films were elaborated from FS containing 1 g of LMP/100g of FS and from Cp of 50 g to 79 g of glycerin/100 g of LMP. The LMP was dispersed in water under moderate agitation, and the pH was kept at 2.5-3.5 with the use of acetic acid. The FS were submitted to thermal treatment at different temperatures for 45 minutes. Films were dried in ventilated oven at 37 degrees C/18hr, conditioned at 75% of relative humidity at 25 degrees C/48 hr before analysis of: mechanical properties by puncture test; apparent opacity by spectrophotometer; solubility by immersion in water; and water vapor permeability by the gravimetric method. In general, films showed good appearance, translucent, easily handled and touchable, except for the films formed with pH 2.5 and at a low temperature (35 degrees C), with a medium thickness of 0.400 +/- 0.005 mm. The pH of the FS significantly affected all the physical properties under study. The temperature of the thermal treatment of the FS greatly affected the force at the rupture, solubility and water vapor permeability. This treatment can promote intermolecular interactions through the formation of disulphide bonds; however a very intense treatment can reverse this effect by irreversible structural alterations in the proteins. The glycerol concentration affected considerably all the properties under study, with the exception of the apparent opacity. Plasticizer increases the mobility of macromolecules with consequences in all physical properties.

Effects of Repeated Stress on Distal Airway Inflammation, Remodeling and Mechanics in an Animal Model of Chronic Airway Inflammation

Background/Aims: Epidemiological studies suggest that stress has an impact on asthmatic exacerbations. We evaluated if repeated stress, induced by forced swimming, modulates lung mechanics, distal airway inflammation and extracellular matrix remodeling in guinea pigs with chronic allergic inflammation. Methods: Guinea pigs were submitted to 7 ovalbumin or saline aerosols (1-5 mg/ml during 4 weeks; OVA and SAL groups). Twenty-four hours after the 4th inhalation, guinea pigs were submitted to the stress protocol 5 times a week during 2 weeks (SAL-S and OVA-S groups). Seventy-two hours after the 7th inhalation, guinea pigs were anesthetized and mechanically ventilated. Resistance and elastance of the respiratory system were obtained at baseline and after ovalbumin challenge. Lungs were removed, and inflammatory and extracellular matrix remodeling of distal airways was assessed by morphometry. Adrenals were removed and weighed. Results: The relative adrenal weight was greater in stressed guinea pigs compared to non-stressed animals (p < 0.001). Repeated stress increased the percent elastance of the respiratory system after antigen challenge and eosinophils and lymphocytes in the OVA-S compared to the OVA group (p < 0.001, p = 0.003 and p < 0.001). Neither collagen nor elastic fiber contents were modified by stress in sensitized animals. Conclusions: In this animal model, repeated stress amplified bronchoconstriction and inflammatory response in distal airways without interfering with extracellular matrix remodeling. Copyright (C) 2011 S. Karger AG, Basel