Sildenafil prevents the increase of extravascular lung water and pulmonary hypertension after meconium aspiration in newborn piglets

Meconium aspiration syndrome causes respiratory failure after birth and in vivo monitoring of pulmonary edema is difficult. The objective of the present study was to assess hemodynamic changes and edema measured by transcardiopulmonary thermodilution in low weight newborn piglets. Additionally, the effect of early administration of sildenafil (2 mg/kg vo, 30 min after meconium aspiration) on this critical parameter was determined in the meconium aspiration syndrome model. Thirty-eight mechanically ventilated anesthetized male piglets (Sus scrofa domestica) aged 12 to 72 h (1660 ± 192 g) received diluted fresh human meconium in the airway in order to evoke pulmonary hypertension (PHT). Extravascular lung water was measured in vivo with a PiCCO monitor and ex vivo by the gravimetric method, resulting in an overestimate of 3.5 ± 2.3 mL compared to the first measurement. A significant PHT of 15 Torr above basal pressure was observed, similar to that of severely affected humans, leading to an increase in ventilatory support. The vascular permeability index increased 57%, suggesting altered alveolocapillary membrane permeability. Histology revealed tissue vessel congestion and nonspecific chemical pneumonitis. A group of animals received sildenafil, which prevented the development of PHT and lung edema, as evaluated by in vivo monitoring. In summary, the transcardiopulmonary thermodilution method is a reliable tool for monitoring critical newborn changes, offering the opportunity to experimentally explore putative therapeutics in vivo. Sildenafil could be employed to prevent PHT and edema if used in the first stages of development of the disease.

Application of various antioxidants in the treatment of influenza

We determined the effect of the antioxidants superoxide dismutase, desferrioxamine and allopurinol on the survival of male CBA mice infected intranasally with 2-5 LD50 lung influenza virus A/Aichi/2/68. Survival for at least 20 days was observed for 45% of the mice that received 1000 U/day superoxide dismutase prepared from red blood cells on days 5, 6, 7 and 8 after infection, and 75% survival was observed for mice that received the same dose on days 4, 5, 6, 7 and 8. Desferrioxamine, 25 mg/kg per day and 100 mg/kg per day injected subcutaneously, resulted in survival rates of 5 and 0%, respectively, compared to 10% survival observed for saline-injected controls. Allopurinol at doses of 5 to 50 mg/kg per day had no effect on mouse survival. These data demonstrate the efficacy of superoxide dismutase for the protection of mice against hemorrhagic lung edema. The ineffectiveness of allopurinol suggests that the xanthine oxidase system does not play a major role in hemorrhage or lung edema and that caution is necessary when desferrioxamine is administered during an acute inflammatory process accompanied by erythrocyte lysis

Pressure and time dependence of the cardiopulmonary reflex response in patients with hypertensive cardiomyopathy

The first minutes of the time course of cardiopulmonary reflex control evoked by lower body negative pressure (LBNP) in patients with hypertensive cardiomyopathy have not been investigated in detail. We studied 15 hypertensive patients with left ventricular dysfunction (LVD) and 15 matched normal controls to observe the time course response of the forearm vascular resistance (FVR) during 3 min of LBNP at -10, -15, and -40 mmHg in unloading the cardiopulmonary receptors. Analysis of the average of 3-min intervals of FVR showed a blunted response of the LVD patients at -10 mmHg (P = 0.03), but a similar response in both groups at -15 and -40 mmHg. However, using a minute-to-minute analysis of the FVR at -15 and -40 mmHg, we observed a similar response in both groups at the 1st min, but a marked decrease of FVR in the LVD group at the 3rd min of LBNP at -15 mmHg (P = 0.017), and -40 mmHg (P = 0.004). Plasma norepinephrine levels were analyzed as another neurohumoral measurement of cardiopulmonary receptor response to LBNP, and showed a blunted response in the LVD group at -10 (P = 0.013), -15 (P = 0.032) and -40 mmHg (P = 0.004). We concluded that the cardiopulmonary reflex response in patients with hypertensive cardiomyopathy is blunted at lower levels of LBNP. However, at higher levels, the cardiopulmonary reflex has a normal initial response that decreases progressively with time. As a consequence of the time-dependent response, the cardiopulmonary reflex response should be measured over small intervals of time in clinical studies.

Effect of saline infusion for the maintenance of blood volume on pulmonary gas exchange during temporary abdominal aortic occlusion

We analyzed the effects of saline infusion for the maintenance of blood volume on pulmonary gas exchange in ischemia-reperfusion syndrome during temporary abdominal aortic occlusion in dogs. We studied 20 adult mongrel dogs weighing 12 to 23 kg divided into two groups: ischemia-reperfusion group (IRG, N = 10) and IRG submitted to saline infusion for the maintenance of mean pulmonary arterial wedge pressure between 10 and 20 mmHg (IRG-SS, N = 10). All animals were anesthetized and maintained on spontaneous ventilation. After obtaining baseline measurements, occlusion of the supraceliac aorta was performed by the inflation of a Fogarty catheter. After 60 min of ischemia, the balloon was deflated and the animals were observed for another 60 min of reperfusion. The measurements were made at 10 and 45 min of ischemia, and 5, 30, and 60 min of reperfusion. Pulmonary gas exchange was impaired in the IRG-SS group as demonstrated by the increase of the alveolar-arterial oxygen difference (21 ± 14 in IRG-SS vs 11 ± 8 in IRG after 60 min of reperfusion, P = 0.004 in IRG-SS in relation to baseline values) and the decrease of oxygen partial pressure in arterial blood (58 ± 15 in IRG-SS vs 76 ± 15 in IRG after 60 min of reperfusion, P = 0.001 in IRG-SS in relation to baseline values), which was correlated with the highest degree of pulmonary edema in morphometric analysis (0.16 ± 0.06 in IRG-SS vs 0.09 ± 0.04 in IRG, P = 0.03 between groups). There was also a smaller ventilatory compensation of metabolic acidosis after the reperfusion. We conclude that infusion of normal saline worsened the gas exchange induced by pulmonary reperfusion injury in this experimental model.

Comparison of the effects of lactated Ringer solution with and without hydroxyethyl starch fluid resuscitation on gut edema during severe splanchnic ischemia

The type of fluid used during resuscitation may have an important impact on tissue edema. We evaluated the impact of two different regimens of fluid resuscitation on hemodynamics and on lung and intestinal edema during splanchnic hypoperfusion in rabbits. The study included 16 female New Zealand rabbits (2.9 to 3.3 kg body weight, aged 8 to 12 months) with splanchnic ischemia induced by ligation of the superior mesenteric artery. The animals were randomized into two experimental groups: group I (N = 9) received 12 mL·kg-1·h-1 lactated Ringer solution and 20 mL/kg 6% hydroxyethyl starch solution; group II (N = 7) received 36 mL·kg-1·h-1 lactated Ringer solution and 20 mL/kg 0.9% saline. A segment from the ileum was isolated to be perfused. A tonometric catheter was placed in a second gut segment. Superior mesenteric artery (Q SMA) and aortic (Qaorta) flows were measured using ultrasonic flow probes. After 4 h of fluid resuscitation, tissue specimens were immediately removed for estimations of gut and lung edema. There were no differences in global and regional perfusion variables, lung wet-to-dry weight ratios and oxygenation indices between groups. Gut wet-to-dry weight ratio was significantly lower in the crystalloid/colloid-treated group (4.9 ± 1.5) than in the crystalloid-treated group (7.3 ± 2.4) (P < 0.05). In this model of intestinal ischemia, fluid resuscitation with crystalloids caused more gut edema than a combination of crystalloids and colloids.

Mini-sternotomy for the treatment of aortic valve lesions

OBJECTIVE: To compare inverted-L mini-sternotomy performed above the sternal furcula with conventional sternotomy in patients with aortic valve diseases who undergo surgical treatment. METHODS: We operated upon 30 patients who had aortic valve lesions that had clinical and hemodynamic findings. All patients underwent inverted-L sternotomy, which extended from above the manubrium of the sternum to the 3rd right intercostal space, without opening the pleural cavity. Their ages ranged from 32 to 76 years, and 18 were males and 12 were females. We used negative pressure in a venous ¼-inch cannula, and the patients were maintained in Trendelemburg's position. Twenty-seven patients received bioprostheses with diameters ranging from 23 to 29mm. Three patients underwent only removal of the calcifications of the aortic valve leaflets and aortic commissurotomy. RESULTS: The mean duration of anoxic cardiac arrest was 63.11min. Access was considered good in all patients. One death was due to pulmonary and renal problems not related to the incision. All patients had a better recovery in the intensive care unit, got out of bed sooner, coughed more easily, and performed prophylactic physiotherapeutic maneuvers for respiratory problems more easily and with less pain in the incision. Early ambulation was more easily carried out by all patients. CONCLUSION: Mini-sternotomy proved to be better than the conventional sternotomy because it provided morecomfort for the patients in the early postoperative period, with less pain and greater desire for early ambulation and all its inherent advantages.

Influence of different systems of minimum ventilation on air quality in broiler houses

To maintain a competitive development of the Brazilian aviculture, some measures must be taken to enable the identification and reduction of risks to the health of birds, as well as for the physical environment. Therefore, the aim of this study was to evaluate the effectiveness of three different systems of minimum ventilation (positive pressure - SVMP, negative pressure - SVMN and natural ventilation - SVMNat) in the air quality during the first 21 days of life of broiler chicks, during winter. Three points were selected along the length to verify ammonia, carbon monoxide and oxygen concentrations at 3a.m., 9a.m., 3p.m. and 9p.m., by the respiration level of birds and workers. The averages of pollutant gases did not exceed the tolerance levels for the three minimum ventilation systems evaluated, which is 20 and 10ppm for the birds level and 20 and 39ppm for the workers level, for ammonia and carbon monoxide, respectively. It was evident that the minimum ventilation systems were appropriately sized for the required minimum ambient air renovation, in respect to ventilation rates applied for the SVMN and SVMP systems, and with air velocity at levels that do not stress the chicks, including for the SVMNat. The three studied systems of minimum ventilation allowed the birds to externalize their productive performance, with values close to the ones considered satisfactory for all evaluated parameters, in accordance with the Brazilian aviculture standards.

Open abdomen management: single institution experience

OBJECTIVE: to evaluate the outcome of abdominal wall integrity of both techniques. METHODS: a retrospective study was carried out at the Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, identifying the patients undergoing temporary abdominal closure (TAC) from January 2005 to December 2011. Data were collected through the review of clinical charts. Inclusion criteria were indication of TAC and survival to definitive abdominal closure. In the post-operative period only a group of three surgeons followed all patients and performed the reoperations. RESULTS: Twenty eightpatients were included. The difference in primary closure rates and mean time for fascial closure did not reach statistical significance (p=0.98 and p=0.23, respectively). CONCLUSION: VAC and Bogota Bag do not differ significantly regarding the outcome of abdominal wall integrity, due to the monitoring of a specific team and the adoption of progressive closure

Oxygen therapy, continuous positive airway pressure, or noninvasive bilevel positive pressure ventilation in the treatment of acute cardiogenic pulmonary edema

OBJECTIVE: To compare the effects of 3 types of noninvasive respiratory support systems in the treatment of acute pulmonary edema: oxygen therapy (O2), continuous positive airway pressure, and bilevel positive pressure ventilation. METHODS: We studied prospectively 26 patients with acute pulmonary edema, who were randomized into 1 of 3 types of respiratory support groups. Age was 69±7 years. Ten patients were treated with oxygen, 9 with continuous positive airway pressure, and 7 with noninvasive bilevel positive pressure ventilation. All patients received medicamentous therapy according to the Advanced Cardiac Life Support protocol. Our primary aim was to assess the need for orotracheal intubation. We also assessed the following: heart and respiration rates, blood pressure, PaO2, PaCO2, and pH at begining, and at 10 and 60 minutes after starting the protocol. RESULTS: At 10 minutes, the patients in the bilevel positive pressure ventilation group had the highest PaO2 and the lowest respiration rates; the patients in the O2 group had the highest PaCO2 and the lowest pH (p<0.05). Four patients in the O2 group, 3 patients in the continuous positive pressure group, and none in the bilevel positive pressure ventilation group were intubated (p<0.05). CONCLUSION: Noninvasive bilevel positive pressure ventilation was effective in the treatment of acute cardiogenic pulmonary edema, accelerated the recovery of vital signs and blood gas data, and avoided intubation.

Paraquat poisoning: an experimental model of dose-dependent acute lung injury due to surfactant dysfunction

Since the most characteristic feature of paraquat poisoning is lung damage, a prospective controlled study was performed on excised rat lungs in order to estimate the intensity of lesion after different doses. Twenty-five male, 2-3-month-old non-SPF Wistar rats, divided into 5 groups, received paraquat dichloride in a single intraperitoneal injection (0, 1, 5, 25, or 50 mg/kg body weight) 24 h before the experiment. Static pressure-volume (PV) curves were performed in air- and saline-filled lungs; an estimator of surface tension and tissue works was computed by integrating the area of both curves and reported as work/ml of volume displacement. Paraquat induced a dose-dependent increase of inspiratory surface tension work that reached a significant two-fold order of magnitude for 25 and 50 mg/kg body weight (P<0.05, ANOVA), sparing lung tissue. This kind of lesion was probably due to functional abnormalities of the surfactant system, as was shown by the increase in the hysteresis of the paraquat groups at the highest doses. Hence, paraquat poisoning provides a suitable model of acute lung injury with alveolar instability that can be easily used in experimental protocols of mechanical ventilation

Variable positive end-expiratory pressure can maintain oxygenation in experimental acute respiratory distress syndrome induced by oleic acid in dogs

The use of positive end-expiratory pressure (PEEP) or lung recruitment maneuvers (RM) to improve oxygenation in acute respiratory distress syndrome (ARDS) is used but it may reduce cardiac output (CO). Intermittent PEEP may avoid these complications. Our objective was to determine if variable PEEP compared with constant PEEP is capable of maintaining arterial oxygenation and minimizing hemodynamic alterations with or without RM. Eighteen dogs with ARDS induced by oleic acid were randomized into three equal groups: group 1, low variable PEEP; group 2, high variable PEEP, and group 3, RM + high variable PEEP. All groups were submitted to constant PEEP, followed by variable PEEP (PEEP was increased from 5 to 10 cmH2O in group 1, and from 5 to 18 cmH2O in the other two groups). PaO2 was higher in group 3 (356.2 ± 65.4 mmHg) than in group 1 (92.7 ± 29.7 mmHg) and group 2 (228.5 ± 72.4 mmHg), P < 0.05. PaO2 was maintained during variable PEEP except in group 2 (318.5 ± 82.9 at constant PEEP to 228.5 ± 72.4 at variable PEEP). There was a reduction in CO in group 3 after RM (3.9 ± 1.1 before to 2.7 ± 0.5 L·min-1·(m2)-1 after; P < 0.05), but there was not any difference between constant and variable PEEP periods (2.7 ± 0.5 and 2.4 ± 0.7 L·min-1·(m2)-1; P > 0.05. Variable PEEP is able to maintain PaO2 when performed in combination with RM in dogs with ARDS. After RM, CO was reduced and there was no relevant difference between the variable and constant PEEP periods.

Syndromic surveillance: etiologic study of acute febrile illness in dengue suspicious cases with negative serology. Brazil, Federal District, 2008

With the aim of identifying the etiology of acute febrile illness in patients suspected of having dengue, yet with non reagent serum, a descriptive study was conducted with 144 people using secondary serum samples collected during convalescence. The study was conducted between January and May of 2008. All the exams were re-tested for dengue, which was confirmed in 11.8% (n = 17); the samples that remained negative for dengue (n = 127) were tested for rubella, with 3.9% (n = 5) positive results. Among those non reactive for rubella (n = 122), tests were made for leptospirosis and hantavirus. Positive tests for leptospirosis were 13.9% (n = 17) and none for hantavirus. Non reactive results (70.8%) were considered as Indefinite Febrile Illness (IFI). Low schooling was statistically associated with dengue, rubella and leptospirosis (p = 0.009), dyspnea was statistically associated with dengue and leptospirosis (p = 0.012), and exanthem/petechia with dengue and rubella (p = 0.001). Among those with leptospirosis, activities in empty or vacant lots showed statistical association with the disease (p = 0.013). Syndromic surveillance was shown to be an important tool in the etiologic identification of IFI in the Federal District of Brazil.

Safety and efficacy of coronary stent implantation. Acute and six month outcomes of 1,126 consecutive patients treated in 1996 and 1997

PURPOSE: The authors analyzed the 30-day and 6-month outcomes of 1,126 consecutive patients who underwent coronary stent implantation in 1996 and 1997. METHODS: The 30-day results and 6-month angiographic follow-up were analyzed in patients treated with coronary stents in 1996 and 1997. All patients underwent coronary stenting with high-pressure implantation (>12 atm) and antiplatelet drug regimen (aspirin plus ticlopidine). RESULTS: During the study period, 1,390 coronary stents were implanted in 1,200 vessels of 1,126 patients; 477 patients were treated in the year 1996 and 649 in 1997. The number of percutaneous procedures performed using stents increased significantly in 1997 compared to 1996 (64 % vs 48%, p=0.0001). The 30-day results were similar in both years; the success and stent thrombosis rates were equal (97% and 0.8%, respectively). The occurrence of new Q wave MI (1.3% vs 1.1%, 1996 vs 1997, p=NS), emergency coronary bypass surgery (1% vs 0.6%, 1996 vs 1997, p=NS) and 30-day death rates (0.2% vs 0.5%, 1996 vs 1997, p=NS) were similar. The 6-month restenosis rate was 25% in 1996 and 27% in 1997 (p= NS); the target vessel revascularization rate was 15% in 1996 and 16% in 1997 (p = NS). CONCLUSIONS: Intracoronary stenting showed a high success rate and a low incidence of 30-day occurrence of new major coronary events in both periods, despite the greater angiographic complexity of the patients treated with in 1997. These adverse variables did not have a negative influence at the 6-month clinical and angiographic follow-up, with similar rates of restenosis and ischemia-driven target lesion revascularization rates.

Influence of balloon pressure inflation in patients undergoing primary coronary stent implantation during acute myocardial infarction: a quantitative coronary angiography analysis

OBJECTIVE:To verify the influence of moderate- or high-pressure balloon inflation during primary coronary stent implantation for acute myocardial infarction. METHODS: After successful coronary stent implantation, 82 patients were divided into 2 groups according to the last balloon inflation pressure: group 1 (³12 to <16 atm) and group 2 (³16 to 20 atm), each with 41 cases. All patients underwent late coronary angiography. RESULTS: In group 1, the mean stent deployment pressure was 13.58±0.92 atm, and in the group 2 it was 18.15±1.66 atm. Stents implanted with moderate pressures (³12 to <16 atm) had a significantly smaller postprocedural minimal lumen diameter, compared to with those with higher pressure, with lesser acute gain (2.7± 0.4 mm vs 2.9±04 mm; p=0.004), but the late lumen loss (0,9±0,8 mm vs 0,9±0,6 mm) and the restenosis (22% vs. 17.1%) and target-vessel revascularization rates (9.8% vs 7.3%) were similar between the groups. CONCLUSION: During AMI stenting, the use of high pressures (³16 atm) did not cause a measurable improvement in late outcome, either in the late loss, its index, and the net gain, or in clinical and angiographic restenosis rates.