Current aspects of acute respiratory distress syndrome in children

Acute respiratory distress syndrome (ARDS) is a frequent condition in pediatric intensive care units. The mortality remains high despite advances in conventional mechanical ventilation and aetiological treatment. Several animal studies have documented lung injury during mechanical ventilation with high tidal volume, and clinical investigations have shown that in human ARDS, most ventilation is distributed to the small areas of remaining aerated lung resulting in overdistension of these areas and lung injury ("baby lung" theory). Nevertheless the usefulness of extrapulmonary gas exchange remains much debated. New ventilatory strategies have been developed in order to reduce ventilator-induced lung injury and to improve systemic oxygenation but multicentric randomized clinical trials are needed before these strategies can be validated.     

Respiratory mechanics and surfactant in the acute respiratory distress syndrome

1. Although abnormalities in pulmonary surfactant were initially implicated in the pathogenesis of the acute respiratory distress syndrome (ARDS) 30 years ago, most subsequent research has focused on mediators of the parenchymal acute lung injury (ALI) and the associated increase in alveolocapillary permeability. 2. Surfactant is essential for normal breathing and the severity of ALI correlates with surfactant dysfunction and abnormalities in surfactant composition; however, no relationship has been shown with respiratory system compliance. In neonates and most animal models, respiratory system compliance will directly reflect the elastic properties of the lung. However, the greater vertical height of the chest wall in adults, in combination with the increase in lung density due to ALI, results in dependent collapse of alveoli. Because simple, global measurement of compliance is strongly influenced by the volume of aerated lung, alternative measures of respiratory mechanics may reflect surfactant dysfunction. 3. Using a dynamic, volume-dependent model of respiratory mechanics to indirectly reflect this heterogeneous inflation, we have found direct relationships with surfactant composition in patients with ARDS. A failure of surfactant to increase surface tension in large alveoli may also explain why lung overdistension occurs at relatively low pressures. Furthermore, surfactant dysfunction will exaggerate heterogeneous lung inflation, augmenting regional overinflation, and is essential for ALI secondary to repetitive opening and closing of alveoli during tidal ventilation. 4. Ventilation-induced ALI has also been shown to result in massive increases in pro-inflammatory cytokines within the lung. Because ALI itself fails to compartmentalize cytokines, with spillover into the systemic circulation resulting in distant organ dysfunction, surfactant dysfunction may have widespread implications.     

Open-lung biopsy in patients with acute respiratory distress syndrome

Occupational exposures contribute to the morbidity and mortality of many diseases. However, occupational diseases continue to be underrecognized even though they are responsible for an estimated 860,000 illnesses and 60,300 deaths each year. Family physicians can play an important role in improving the recognition of occupational disease, preventing progressive illness and disability in their own patients, and contributing to the protection of other workers similarly exposed. This role can be maximized if physicians raise their level of suspicion for workplace disease, develop skills in taking occupational histories and establish routine access to occupational health resources.     

Eicosanoids and fat emulsions in acute respiratory distress syndrome patients

Laparoscopic splenectomy has been accepted as a feasible extension of minimally invasive surgery, which has undergone dramatic improvements in both technology and instrumentation. We performed a laparoscopic splenectomy in a 7-year-old girl with hereditary spherocytosis. The patient recovered rapidly and returned to unrestricted activities quickly. The appropriate positioning of each laparoscopic port is essential for a good operative view and smooth access. It is also important to dissect the hilum of the spleen meticulously. Laparoscopic splenectomy in the pediatric age group appears to be another promising extension of laparoscopic surgery.     

Pharmacologic adjuncts to mechanical ventilation in acute respiratory distress syndrome

This article reviews pharmacologic approaches to treating acute respiratory distress syndrome (ARDS). The authors discuss the therapeutic effects of ketoconazole, antioxidants, corticosteroids, surfactant, ketanserin, pentoxifylline, bronchodilators, and almitrine in ARDS. Current animal data and proposed mechanics which may foster future pharmacologic therapies are also examined.     

Improved oxygenation utilizing a prone positioner in patients with acute respiratory distress syndrome

OBJECTIVES: (a) To determine whether placing patients with acute respiratory distress syndrome in the prone position by a light-weight portable support frame improves oxygenation, (b) whether one can determine which patients benefit from prone positioning, and (c) to determine an effective technique for prone positioning of patients. DESIGN: Prospective, controlled trial without blinding. SETTING: Medical intensive care units in two urban university-affiliated hospitals. PATIENTS: Fifteen patients meeting a standard definition for acute respiratory distress syndrome were studied prospectively. Each patient acted as his own control for purposes of comparison. INTERVENTION: Patients were assigned randomly to begin in either supine or prone positions. The positioning frame was used to turn patients from one position to the other, and oxygenation, ventilation, respiratory mechanics, and hemodynamics were measured. RESULTS: Significantly better oxygenation was seen in the prone positions than in the supine (P < 0.05). In the overall population there was a decrease in AaDO2 of 21 mmHg when the patients were placed prone. The groups were then divided into responders (n = 9) and nonresponders (n = 6). There were significant differences between the groups (but not between positions) regarding PaO2, baseline, PaCO2, pulmonary artery pressures, and peak inspiratory pressures on the ventilator and in ICU length of stay and time on mechanical ventilatory support. CONCLUSION: Prone positioning improves oxygenation in the majority of patients studied and can be achieved relatively easily.     

Rescue therapy for the acute respiratory distress syndrome (ARDS)

The potential risk of feto-maternal haemorrhage following coelocentesis was examined in 17 singleton pregnancies at 6-11 weeks of gestation by measuring maternal serum concentration of alpha fetoprotein (AFP) before and 1 and 10 min after the procedure. There was no significant difference between the maternal serum AFP concentration before coelocentesis (median 7.5, range 4.5-21.5 IU) compared to the values at 1 min (median 8.6, range 3.9-17.8; Z = -0.504, P = 0.614), and 10 min (median 7.5, range 5.7-20.6; Z = -0.432, P = 0.666) after the procedure. These findings demonstrate that coelocentesis is not associated with significant feto-maternal haemorrhage.     

Leptospirosis: a rare cause of acute respiratory distress syndrome in metropolitan France]

We report a case of acute respiratory distress with fatal outcome due to ictero-hemorrhagic leptospirosis. The association with an intra-alveolar hemorrhage suggested the corticosteroid therapy would be useful in this case.     

Patients with acute respiratory distress syndrome mechanically ventilated in prone position

Animal experiments and human studies have shown better oxygenation in mechanically ventilated patients with ARDS when the patient is situated in the prone position. In contradiction to former theories of a gravitational gradient of lung perfusion, a number of investigators have found that lung perfusion is preferentially distributed to the dorsal lung regions regardless of body position. The basal atelectasis and oedema in ARDS are resolved and only partly distributed anteriorly in the prone position, and these areas are thereby better ventilated. The combination of better ventilation and unchanged perfusion improves the ventilation/perfusion ratio and decreases the shunt in the prone position. In two cases of prone position in mechanically ventilated patients the PaO2/FiO2 ratio increased from 7.5 to 14.3 and from 8.8 to 19.8 after one hour in the prone position, and some of the improvement was permanent. Prone position has only minor side effects and is recommended as the first choice amongst adjunct therapies in mechanical ventilation in patients with ARDS remaining hypoxic in conventional therapy in the supine position.     

Adult respiratory distress syndrome

In this article the authors present a case of successful treatment of a 54-year old male patient with non-insulin dependent diabetes mellitus (NIDDM) and triple-vessel coronary artery disease who underwent surgical myocardial revascularization and was reoperated on the same day because of excessive bleeding. The patient was given cca 5000 mL of whole blood and cca 3000 mL of blood derivatives. The first postoperative chest X-ray showed radiological signs of ARDS. The therapy was based upon authors' experience and was consisted of controlled mechanical ventilation (respiratory volume 12-15 mL/kg, 10-14 cycles/min, I/E ratio 1:2, FIO2 0.6, PEEP 2-5 cm H2O), daily bronchoscopies with bronchoaspiration, aggressive diuresis, negative fluid balance, specific antibiotic therapy, and last but not least, of prostaglandin E1 (PGE1) 0.5-20 micrograms/kg/min combined with dopamine inotropic support (2-5 micrograms/kg/h). Simple but careful clinical observation still remains a milestone for all therapeutic measures taken in ARDS patients.     

Surfactant replacement therapy in acute respiratory distress syndrome from viral pneumonia

A modified natural surfactant was administered to a patient with life-threatening adult respiratory distress syndrome caused by viral pneumonia. Subsequently, there was a marked improvement in gas exchange. In order to assess the mechanism for improved oxygenation, computed tomography of the lungs was done. Quantitative analysis of the scans taken before and after surfactant administration indicates that improvement in gas exchange was largely due to the expansion of underinflated and collapsed lung areas. Although this is a single case report, it provides insight into the possible beneficial effect of instilled surfactant in severe respiratory distress from viral pneumonia.     

Pustular and erythrodermic psoriasis complicated by acute respiratory distress syndrome

To investigate the mechanisms of the hypolipidemic effect of monatepil, a new class of calcium antagonists with alpha 1-adrenergic blocking activity, we examined the effects of the drug on low-density lipoprotein (LDL) receptor activity and the level of LDL receptor mRNA present in cultured human skin fibroblasts. At concentrations of 2 x 10(-5) M, monatepil increased the binding (248 +/- 43%; mean +/- SD), internalization (374 +/- 18%), and degradation (145 +/- 2%) of 125I-LDL in human skin fibroblasts (n = 3, p < 0.05). Treatment of human skin fibroblasts with 2 x 10(-5) M of monatepil for 6 hours resulted in an increase in LDL receptor mRNA to 163% of the control level (n = 2), as shown by Northern blot analysis. Our results suggest that the hypolipidemic clinical effects of monatepil may be due to increased LDL receptor activity.     

A new view of pulmonary edema and acute respiratory distress syndrome

The old division of lung edema into two categories--cardiogenic (hydrostatic) and noncardiogenic (increased permeability)--is no longer adequate. For instance, it fails to distinguish between the capillary leak caused by acute respiratory distress syndrome from that caused by interleukin-2 treatment. Further, it fails to account for the capillary leak ('stress-failure') that may accompany edema. A modern view of edema must recognize the natural barriers to the formation and spread of edema. These barriers are the capillary endothelium and the alveolar epithelium. Varying degrees of damage to them can account for the varying radiographic and clinical manifestations of lung edema. Thus, interleukin-2 administration causes increased endothelial permeability without causing alveolar epithelial damage. The result is lung edema that is largely confined to the interstitium, causing little hypoxia and clearing rapidly. However, acute respiratory distress syndrome, which is characterized by extensive alveolar damage, causes air-space consolidation, severe hypoxia, and slow resolution. Thus, a reasonable classification of lung edema requires at least four categories: 1) hydrostatic edema; 2) acute respiratory distress syndrome (permeability edema caused by diffuse alveolar damage); 3) permeability edema without alveolar damage; and (4) mixed hydrostatic and permeability edema. The authors emphasize the importance of the barriers provided by the capillary endothelium and the alveolar epithelium in determining the clinical and radiographic manifestations of edema. In general, when the alveolar epithelium is intact, the radiographic manifestations are those of interstitial (not air-space) edema; this radiographic pattern predicts a mild clinical course and prompt resolution.