The ischemia-reperfusion injury is a common pathophysiologic phenomenon in many diseases seen in daily clinical practice. The lung can be affected both directly, as in pulmonary edema after lung transplant or after resolution of pulmonary thromboembolism, and indirectly, as in shock states or after reperfusion injury in distant organs as intestine or lower extremities. The latter situation can occur secondary to aortic occlusion for surgical procedures. Many mediators have been implicated in the ischemia-reperfusion injury: oxygen free radicals, lipid products as thromboxane, adhesion molecules involved in leukocyte-endothelial interaction, tumor necrosis factor, among others. Therapeutic strategies for the reperfusion injury are used only at the experimental level and in very few clinical studies. Antioxidants, inhibitors of lipid mediators and of the leukocyte-endothelial interaction and promoters of blood flow in post-ischemic vessels have been used.

Keywords: Lung. Injury. Reperfusion. Ischemia.

Background: It is questionable whether pressure-controlled ventilation (PCV) has advantages over volume-cycled ventilation (VCV). Objectives: To compare PCV to VCV with decelerating flow profile during assisted and controlled modes in an acute lung injury experimental model. Methods: Severe acute lung injury (PaO2/FIO2 < 100 mmHg) was induced by oleic acid IV infusion (0.05 mg/kg) in seven dogs. The animals were submitted to PCV and VCV in a randomized sequence. After 40 minutes in the assisted mode, ventilation was changed to the controlled mode after neuromuscular blockade. The tidal volume and the inspiratory time were kept constant throughout the experiment. Results: There were no differences in gas exchange (PaO2 and PaCO2), cardiac output or oxygen delivery (DO2) between VCV and PCV. The same was observed regarding maximum airway and plateau pressures, and also to the static compliance. Oxygen consumption (VO2) after neuromuscular blockade was 124 ± 48 in VCV versus 143 ± 50 ml/min in PCV, p = 0.42. In the assisted mode, there was a statistical trend of a higher VO2 in PCV (219 ± 72 versus 154 ± 67 ml/min in VCV, p = 0.06), that was associated with a statistical trend of a higher oxygen cost of breathing (OCB) during assisted PCV, although without statistical significance (31 ± 77 in VCV versus 75 ± 96 ml/min in PCV, p = 0.23), and also in a lower PvO2 (34 ± 7 in PCV versus 42 ± 6 ml/min in VCV, p = 0.02). These occurred despite a higher maximum inspiratory flow in the assisted mode in PCV (58 ± 9 versus 48 ± 4 L/min in VCV, p = 0.01). In both VCV and PCV the institution of controlled ventilation reduced cardiac debit and DO2 in as much as 20% relative to the assisted mode. Conclusions: The implementation of controlled ventilation improved the oxygen delivery/consumption relationship in this severe and with high OCB acute lung injury model. The PCV offered no additional benefits to VCV and it was associated with a higher OCB during the assisted mode.

Keywords: Artificial respiration. Pulmonary gas exchange. Tidal volume.

Recent studies suggest that non-invasive positive pressure ventilation (NPPV) improves clinical signs and gas exchange, apart from avoiding the need for endotracheal intubation in selected patients with acute respiratory failure. In this prospective, open trial in the Intensive Care Unit (Hospital Universitário da Universidade Federal de Juiz de Fora), the authors evaluated the efficacy and security of using NPPV in patients with acute respiratory failure. Twenty-five patients with clinical or gasometric diagnosis of acute respiratory failure (respiratory rate > 25 breaths/min, accessory muscle use, PaO2 < 60 mmHg, PaCO2 > 50 mmHg after supplemental oxygen) received NPPV. Fifteen patients (60%) were successfully ventilated with NPPV, avoiding the tracheal intubation. After two hours with NPPV, the respiratory rate was reduced (from 36 ± 2 breaths/min to 26 ± 1 breaths/min, p < 0.01) and the PaO2 increased (from 76 ± 6 mmHg to 100 ± 12 mmHg, p < 0.05). Among the patients with hypercapnia, after two hours, the PaCO2 decreased (from 60 ± 2 mmHg to 49 ± 3 mmHg, p < 0.05). Four patients (16%) presented complications with facial skin necrosis, but only one had the NPPV stopped. Among the patients who did not respond to the method, three did not adapt to the NPPV and seven had it interrupted because of clinical deterioration. The authors conclude that NPPV is a safe option that can be used to treat selected patients with acute respiratory failure.

Objective: Evaluate the efficacy of the ampicillin-quinolone association in the treatment of severe community-acquired pneumonia. Design: Open, prospective study carried out at the Emergency room of the Hospital Universitário da Universidade Federal de Juiz de Fora. Patients and methods: From March 1994 to September 1995, the authors studied 23 patients with fever and with at least three of the following symptoms: cough, purulent sputum, pleuritic thoracic pain, leukocytosis or leukopenia, and a chest radiological examination showing infiltrations compatible with pneumonia diagnosis. The patient diagnosis would be severe pneumonia if he met the criteria of severe sepsis as established by the American College of Chest Physicians and by the Society of Critical Care Medicine. Results: 23 patients were studied. One was excluded after having a pulmonary tuberculosis diagnosis; 21 patients were considered cured and one died. Adverse drug effects occurred in one patient who presented a mild pharmacodermia. Conclusion: Ampicillin-quinolone is efficient in the treatment of severe community-acquired pneumonia.

Introduction: Surgical procedures requiring aortic occlusion have been associated with pulmonary reperfusion injury. The authors studied the pulmonary edema in a reperfusion injury model by aortic occlusion in rats. Material and methods: Thirty-three Wistar rats were anesthetized with intraperitoneal injection of sodium pentobarbital (20 mg/kg). Using a midline abdominal incision, the infra-renal aorta was isolated and the animals were randomized into three groups. Ischemia-reperfusion group (IRG, n = 5): rats that underwent 30 min of aorta occlusion and were followed during 120 min of reperfusion. Ischemia group (IG, n = 5): rats that underwent 30 min of aorta occlusion. Control group (CG, n = 5): rats that underwent sham operations without aorta occlusion and were followed during 150 min. Histopathologic examination of the right lung was performed. The pulmonary edema was studied by morphometric analysis and so was the leukocytes infiltration. Eighteen rats (6 rats in each group) were studied with respect to lung fresh/dry weight ratio. ANOVA was used to analyze the morphometric results and the lung fresh/dry weight ratio, with Bonferroni adjustment for paired multiple comparisons. Animals of the IRG presented more pulmonary edema than those of the IG and CG (0.24 vs. 0.17 and 0.17, p < 0.001). There was no difference between the groups regarding the lung fresh/dry weight ratio. There were more inflammatory cells in the lungs of the rats submitted to ischemia-reperfusion. The authors concluded that infra-renal abdominal aorta cross-clamping and unclamping are associated with pulmonary edema. This edema is not induced by elevation of the hydrostatic pressure due to the aortic occlusion, since it was not seen in animals that were only submitted to ischemia.

Keywords: ischemia, reperfusion, pulmonary edema, inbred strains rats

Objective: To compare the effects of early tracheostomy and of late tracheostomy in patients with acute severe brain injury. Methods: A retrospective study involving 28 patients admitted to the ICU of the Federal University of Juiz de Fora University Hospital in Juiz de Fora, Brazil, diagnosed with acute severe brain injury and presenting with a Glasgow coma scale (GCS) score < 8 within the first 48 h of hospitalization. The patients were divided into two groups: early tracheostomy (ET), performed within the first 8 days after admission; and late tracheostomy (LT), performed after postadmission day 8. At admission, we collected demographic data and determined the following scores: Acute Physiology and Chronic Health Evaluation (APACHE) II, GCS and Sequential Organ Failure Assessment (SOFA). Results: There were no significant differences between the groups (ET vs. LT) regarding the demographic data or the scores: APACHE II (26 ± 6 vs. 28 ± 8; p = 0.37), SOFA (6.3 ± 2.7 vs. 7.2 ± 3.0; p = 0.43) and GCS (5.4 ± 1.7 vs. 5.5 ± 1.7; p = 0.87). The 28-day mortality rate was lower in the ET group (9% vs. 47%; p = 0.04). Nosocomial pneumonia occurring within the first 7 days was less common in the ET group, although the difference was not significant (0% vs. 23%; p = 0.13). There were no differences regarding the occurrence of late pneumonia or in the duration of mechanical ventilation between the groups. Conclusions: On the basis of these findings, early tracheostomy should be considered in patients with acute severe brain injury.

Keywords: Tracheostomy; Pulmonary ventilation; Coma.