Rapid diagnosis of respiratory distress syndrome by oral aspirate in premature newborns / Diagnóstico rápido da síndrome do desconforto respiratório por aspirado bucal em recém-nascidos prematuros

Abstract Objective: The stable microbubble test on gastric aspirate and on amniotic fluid has been used for the diagnosis of respiratory distress syndrome in the newborn. However, no study has performed this test on oral aspirates from premature infants. The objective of this study was to evaluate the performance of the stable microbubble test on oral aspirates from preterm newborns to predict respiratory distress syndrome. Method: This study included infants with gestational age <34 weeks. Oral fluids were obtained immediately after birth and gastric fluids were collected within the first 30 minutes of life. The samples were frozen and tested within 72 hours. Results: The sample was composed of paired aspirates from 64 newborns, who were divided into two groups: respiratory distress syndrome group (n = 21) and control group (n = 43). The median (interquartile range) of the stable microbubble count in the oral samples of infants with respiratory distress syndrome was significantly lower than that of infants who did not develop respiratory symptoms: respiratory distress syndrome group = 12 (8 -22) stable microbubbles/mm2; control group = 100 (48 -230) microbubbles/mm2 (p < 0.001). The correlation between microbubble count in gastric and oral aspirates was 0.90 (95% confidence interval = 0.85 -0.95; p < 0.001). Considering a cut-off point of 25 microbubbles/mm2, the sensitivity and the specificity of the stable microbubble test were 81.4% and 85.7%, respectively. Conclusion: The study suggests that the stable microbubble test performed on oral aspirate is a reliable alternative to that performed on gastric fluid for the prediction of respiratory distress syndrome in the newborn.

Resumo Objetivo: O teste das microbolhas estáveis no aspirado gástrico e no líquido amniótico foi usado no diagnóstico da síndrome do desconforto respiratório do recém-nascido. Contudo, nenhum estudo fez esse teste nos aspirados bucais de neonatos prematuros. O objetivo deste estudo foi avaliar o desempenho do teste das microbolhas estáveis em aspirados bucais de recém-nascidos prematuros para prever síndrome do desconforto respiratório. Método: Este estudo incluiu neonatos com idade gestacional < 34 semanas. Os fluidos orais foram obtidos imediatamente após o nascimento e os fluidos gástricos foram coletados nos primeiros 30 minutos de vida. As amostras foram congeladas e testadas em 72 horas. Resultados: A amostra foi composta de aspirados pareados de 64 recém-nascidos, divididos em dois grupos: grupo de síndrome do desconforto respiratório (n = 21) e grupo de controle (n = 43). A mediana (intervalo interquartil) da contagem das microbolhas estáveis nas amostras de fluido oral dos neonatos com síndrome do desconforto respiratório foi significativamente menor que a dos neonatos que não desenvolveram sintomas respiratórios: grupo de síndrome do desconforto respiratório = 12 (8-22) microbolhas estáveis/mm2; grupo de controle = 100 (48-230) microbolhas/mm2 (p < 0,001). A correlação entre a contagem das microbolhas nos aspirados gástricos e bucais foi 0,90 (intervalo de confiança de 95% = 0,85-0,95; p < 0,001). Considerando um ponto de corte de 25 microbolhas/mm2, a sensibilidade e a especificidade do teste das microbolhas estáveis foram 81,4% e 85,7%, respectivamente. Conclusão: O estudo sugere que o teste das microbolhas estáveis feito no aspirado bucal é uma opção confiável ao fluido gástrico para a predição da síndrome do desconforto respiratório do recém-nascido.

Phase behaviours of amino-acid based anionic surfactants

The phase behaviours of three types of amino-acid based surfactants were explored. They are Sodium Cocoyl Glutamate [commercially known as Amisoft CS-11], Sodium Lauroyl Glutamate [commercially known as Amisoft LS-11] and Sodium Cocoyl Glycinate [commercially known as Amilite GCS-11]. The optical polarized microscope was used to observe the liquid crystalline phases and to capture images. The existence of liquid crystalline phases was further investigated by small angle X-ray scattering. The phase diagrams were investigated as a function of surfactant concentration and as a function of temperature as well. The rheological behaviours of liquid crystalline phase were also investigated. All surfactants were found to form two-phase region, micellar region at low concentration while liquid crystalline phases were found to form at high concentration

role of pulmonary surfactants [protein A and phospholipids], catecholamines and myoglobin in the diagnosis of the cause of death

An important and often one of the most difficult tasks of a medical practitioner or pathologist is the investigation of the cause of death. The aim of this work is to assess the post mortem levels of serum protein A [SP-A], pulmonary as well as serum phospholipids, catecholamines and myoglobin in forensic autopsies as a guide to diagnose the cause of death. This study was done on 120 cadavers 75 males and 45 females with ranging age from newborn up to 62 years old. They included 2 groups: the first group consisted of 110 cases died from various types of trauma or due to some diseases [experimental group] and the second group consists of 10 cases died without trauma or disease [control group]. The experimental group subdivided into eleven subgroups of various types of trauma or disease. Each was 10 cases for each of the followings:- strangulation, hanging, drowning, blunt head injuries, burns, sharp weapon injuries, heat stroke, electrical fatalities, hemorrhagic shock, myocardial infarction and interstitial pneumonia. It was found that the level of serum protein A [SP-A] showed a very highly significant increase in cases of interstitial pneumonia and highly significant increase in cases of drowning burns and sharp weapon injuries. Also it showed a significant increase in cases of strangulation hanging, blunt head injuries and electrical injuries, while insignificant increase in, heat stroke hemorrhagic shock and myocardial infarction as compared to the control had been shown. Serum phospholipids showed a very highly significant increase in strangulation, hanging, drowning, electrical injuries and interstitial pneumonia and highly significant increase in blunt head injuries, burn, sharp weapon injuries and heat stroke. Also it showed a significant increase in hemorrhagic shock and myocardial infarction as compared to the control. Lung surfactant phospholipids showed insignificant, increase in different cases of death as compared to the control. Adrenaline and noradrenoline showed highly significant increase in case of strangulation, hanging, drowning, myocardial infarction and interstitial pneumonia respectively. Adrencline showed a significant increase in blunt head injuries, burns, sharp weapon injuries, heat stroke and hemorrhagic shock as compared to the control. Noradrenaline showed insignificant increase in heat stroke as compared to the control. Myoglobin showed a significant increase in cases of blunt head injuries, burns, sharp weapon injuries, heat stroke and electrical injuries. While insignificant increase in cases of strangulation, hanging, drowning, hemorrhagic shock, myocardial infarction and interstitial pneumonia, as compared to the control

Cyanide induced changes in dynamic pulmonary mechanics in rats.

Effect of subcutaneously (s.c.) administered potassium cyanide (0.5 and 1.0 LD50) and inhalation of hydrogen cyanide (55 ppm or 60.6 mg/m3) for 30 minutes was studied on various physiological parameters related to dynamic pulmonary mechanics in anaesthetized rats. Total pulmonary phospholipid with its fractions were also estimated. Both s.c. (1.0 LD50) and inhalation exposures increased air flow, transthoracic pressure and tidal volume accompanied by significant decrease in pulmonary phospholipids. Inhalation of hydrogen cyanide also exhibited direct effect on the pulmonary cells as evidenced by decreased compliance. The study suggests that inhalation of cyanide is more injurious compared to parenteral route.

Isolation & chemical composition of lung surfactant from human amniotic fluid.

Lung surfactant was isolated from human amniotic fluid collected at term and studied with reference to the material isolated from human and rabbit lung lavage. The isolated material showed 58 per cent lipid by dry weight, 29 per cent protein and relatively smaller amounts of nucleic acids, sialic acid and hexose. Phosphatidyl choline was the predominant phospholipid species and accounted for 46 per cent of the total lipid by weight, followed by phosphatidyl glycerol (7%) and phosphatidyl ethanolamine (5%). Cholesterol was the major neutral lipid fraction present (10%) and was almost entirely in the free form. Other lipid fractions present in minor quantity were triglycerides, esterified cholesterol, phosphatidyl serine, phosphatidyl inositol and sphingomyelin. The material contained a very high degree of alkaline phosphatase activity, while other enzymes such as acid phosphatase, glucose-6-phosphatase, ATPases, 5'-nucleotidase and beta-N-acetyl glucosaminidase were also present.

Analysis of the major surfactant-associated proteins in human lung.

The protein component of human pulmonary surfactant was analysed. A purified surfactant preparation, after delipidation, was subjected to gel filtration on Sephadex G-200. The proteins present in the surfactant were categorised by means of SDS-polyacrylamide gel electrophoresis into serum and non-serum components. Molecular masses determination showed the presence of three sub-groups with molecular masses of 60-68 kDa, 28-36 kDa and 10-18 kDa, respectively. Antiserum generated against 28-36 kDa protein strongly reacted with the purified surfactant and amniotic fluid, while it did not show any cross reactivity with other groups of proteins and serum in a double diffusion immunoprecipitation assay. We propose that this protein is the major non-serum surfactant-associated protein present in human lung surfactant.

Effect of drugs used in pulmonary edema (frusemide and combination of etofylline and theophylline) on surfactant system of lung.

Pulmonary surfactant activity of healthy male albino rats was estimated in terms of the maximum and minimum surface tension values of alveolar washings and the phospholipid content of the extract. The results obtained in these (control) animals were compared with those in two groups of animals treated with therapeutic doses of frusemide and a combination of etofylline and theophylline. A significant increase in surfactant activity in terms of surface tension values and phospholipid content was observed with frusemide, whereas a significant increase in phospholipid content without a change in surface tension values was observed in the case of combination of etofylline and theophylline. These findings suggest that frusemide in addition to its diuretic action, increases the surfactant activity of lung. This might be another mechanism by which it provides relief in pulmonary edema patients. The study also indicates that phospholipid concentration need not always reflect surfactant activity of lung.

The effect of vagotomy and hydrocortisone administration on pulmonary surfactant activity in adult albino rats.

The role of vagus and hydrocortisone in the regulation of lung surfactant was studied in adult albino rats. Dynamic surface tension and phospholipid content were measured in the lung wash for estimating surfactant activity. The results indicate that vagotomy significantly decreases the surfactant activity whereas hydrocortisone does not alter it. But when hydrocortisone was administered prior to vagotomy it could prevent the decrease in surfactant activity. Thus it is concluded the regulation of lung surfactant in the adult lung is mainly by vagus nerve and hydrocortisone as such has no role but in the absence of vagal regulation hydrocortisone could maintain normal lung surfactant activity.

Alveolar stability of altitude raised rats.

On the lining of alveolar membrane of the lung presence of surfactant, a surface tension lowering agent which is a phospholipid in nature, is well established. A good correlation exists between pulmonary lecithin, the principle constituent of surfactant system and alveolar stability. The production of surface active material in the type II cells is oxygen dependent and is affected by hypoxia. The chemical and physical nature of the surfactant in the lungs of the rats raised at high altitude has been studied in comparison with that of sea level control. Eighteen male adult rats raised at high altitude (3520 m) were used. Phospholipids (Phosphatidyl Choline, Phosphatidyl ethanolamine, Lysophosphatidyl choline, Lysophosphatidyl ethanolamine and Sphingomyelin) were estimated by thin layer chromatography, stability index by Pattle's bubble technique and dynamic surface tension have also been studied to assess the surfactant activity of the lung. The results indicate that there was a decrease in lung surfactant as measured by chemical analysis. However, stability ratio measurements showed that there was very little change in the stability ratio (Sr) as the value of both groups lay in the normal range namely 0.6 to 0.9 hence the lungs of high altitude raised rats had normal alveolar stability. Surface tension values of alveolar lavage in altitude raised animals were also similar to those of normal rats. It is concluded that the rats raised at altitude show a lowering of surfactant as estimated chemically but the stability ratio is not significantly altered to indicate alveolar instability. In the altitude rats lesser quantum of surfactant is adequate to maintain alveolar stability.