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Biomedical subjects

T A Merritt

Publications and source records attributed to T A Merritt.

At least 109 records · Page 6Linked to original sources
PubMed1982

Control of peak inspiratory pressure during manual ventilation. A controlled study.

The accuracy and stability of manual ventilation can contribute to the quality of ventilation and the prevention of acute and chronic pulmonary complications in neonates. In this study pediatric house staff and nurses in the intensive care nursery manually ventilated a teaching mannequin at predetermined "low" and "high" peak inspiratory pressures. Without using a pressure manometer, 18% and 13% achieved desired peak inspiratory pressures of 15 and 30 cm H2O, respectively, vs 72% and 74% when a manometer was used for a mean of 90 ventilations. Median and maximal group deviations from the assigned pressures were significantly lower when a pressure gauge was used. Our results demonstrated that accuracy of manual ventilation can be better achieved when a manometer is used in conjunction with infant resuscitation bags.

Humans↗
PubMed1982

Preschool assessment of infants with a patent ductus arteriosus: comparison of ligation and indomethacin therapy.

We report the preschool growth and development of preterm infants with problematic patent ductus artferiosus requiring either surgical ligation or indomethacinn treatment in the neonatal period. Of 60 who completed longitudinal growth assessments, no differences in growth to 3 years could be demonstrated except for four cases of regressed retinopathy of prematurity among the ligated infants. Developmental tests (Bayley Scales of Infant Development and the Peabody Picture Vocabulary Test) showed no group differences at preschool ages. Although psychomotor performance on the Bayley Scales in the first 1 1/2 years was significantly lower among the surgically treated infants, later analysis showed that a similar number in both treatment groups scored within the normal range. No selective short- or long-term adverse effects of indomethacin treatment could be demonstrated.

Body Height↗
PubMed1982

Parenteral indomethacin for closure of the patent ductus arteriosus. Clinical experience with 67 preterm infants.

During a 19-month period, 23% of preterm infants had symptomatic patent ductus arteriosus (PDA). Intravenous indomethacin was administered to 67 infants with successful closure in 91% of the patients and in 83% of those with birth weights less than 1,000 g. No differences were found between the number of doses required and birth weight, gestational age, or age at initial therapy. Transient alterations in renal function were common after therapy, but mild renal failure occurred in only four infants. The incidence of intraventricular hemorrhage and necrotizing enterocolitis in treated infants was similar to that in the total preterm population. Cicatricial retrolental fibroplasia developed in one patient. Bronchopulmonary dysplasia occurred more frequently in infants with PDA, but a decreased incidence was found after early ductal closure. Intravenous indomethacin administration successfully effects ductal closure without major complications in preterm infants.

Age Factors↗
PubMed1982

Oxygen exposure in the newborn guinea pig lung lavage cell populations, chemotactic and elastase response: a possible relationship to neonatal bronchopulmonary dysplasia.

Neonatal guinea pig pulmonary response to oxygen exposure FiO2 greater than 0.9 resulted in an increase in total cell number in lung lavage. Alveolar macrophages initially increased within 48 h of exposure. Polymorphonuclear leukocytes and macrophages exceeded age-matched neonatal control values by 72 h of oxygen exposure. By 144 h of life, total inflammatory cell number still exceeded control cell populations. Chemotaxis of alveolar macrophages to N-formyl-methionyl-phenylalanine (1 x 10(-5) M) exceeded chemotaxis of air-exposed controls. Although initially depressed, by 72 h of FiO2 greater than 0.9 polymorphonuclear leukocyte chemotaxis increased 6-fold. Endogenous chemotactic peptides were demonstrated in lung lavage supernatant of oxygen-exposed neonatal guinea pigs. Elastase activity rose in oxygen exposed guinea pigs by 72 h of life. Lung lavage disaturated phosphatidylcholine in oxygen-exposed neonates exceeded control values 4-fold. In a preliminary study, lung effluent elastase activity was found to be increased in human neonates with respiratory distress syndrome over the first days of life compared to infants intubated but without lung disease. In infants developing bronchopulmonary dysplasia, tracheal aspirate protease activity remained greater than 10(-3) U for over 10 days and up to 5 weeks of age.

Animals↗
PubMed1982

Pulmonary lymphatic air: locating "pulmonary interstitial emphysema" of the premature infant.

Pulmonary interstitial air in the premature infant, a complication of hyaline membrane disease and respiratory supportive treatment, is usually described as representing freely dissecting air that has escaped from terminal air spaces to dissect along the bronchovascular bundles of the lung. By inflating the lung and fixing it in this state, the interstitial air is identified within the lymphatics of the interlobular septae and visceral pleura. On a radiography, this lymphatic air is seen as a pattern of fine linear lucencies involving a lobe or an entire lung. With increasing distension, oval and cystic lucencies are seen representing air in dilated septal lymphatics and lymphatics of the visceral pleura. Pneumothorax results from rupture of these collections into the pleural space.

Female↗
PubMed1981

Skin-surface CO2 measurement in sick preterm and term infants.

To evaluate the clinical usefulness of a heated CO2 electrode at 43 degrees C for measurement of skin surface PCO2, we made 157 simultaneous determinations of PSCO2 and arterial PCO2. Arterial samples were drawn from an umbilical artery catheter, and the PaCO2 was measured within two minutes and was corrected for body temperature. We obtained two to 43 paired samples per infant from 22 infants (gestational age = 27 to 40 weeks) during the first 12 days of life. Over a four-hour period there was no significant drift of the electrode calibration and no significant change in PSCO2-PaCO2 (delta). Over the range PaCO2 26 to 72 torr, PaCO2 was linearly related to PSCO2 (PaCO2 = 0.37 PSCO2, + 17.46) r = 0.79). To pursue the factors which determine delta, we performed step-wise multiple regression analysis and found that the only significant independent variables were PSCO2 and postnatal age (delta = 0.79 CO2 [torr] - 1.2 age [days] - 23.9 [r = 0.93]). Insignificant independent variables were blood pressure, gestational age, hematocrit, weight at time of study, and drug therapy.

Carbon Dioxide↗
PubMed1981

Early closure of the patent ductus arteriosus in very low-birth-weight infants: a controlled trial.

A controlled clinical trial comparing early closure (mean = 48.8 hours) of the patent ductus arteriosus using indomethacin to conventional medical management, with intervention only after cardiopulmonary decompensation (mean = 167.4 hours), was undertaken in 24 preterm infants with severe respiratory distress syndrome and evidence of PDA. An interval analysis of one-half the projected sample revealed that infants undergoing early closure of the PDA had significantly reduced occurrence of BPD or mortality by 6 months of age. A comparison of birth weight, Apgar scores, gestational age, age of initial PDA diagnosis, and fluid therapy during the first seven days of life showed no significant differences between early intervention and control groups. At the time of the interval analysis, there were no differences between the groups in duration of intermittent mandatory ventilation or oxygen exposure. Studies will be required to determine whether these and other variables can be altered by early closure of the PDA.

Bronchial Diseases↗
PubMed1981

Newborn tracheal aspirate cytology: classification during respiratory distress syndrome and bronchopulmonary dysplasia.

Cytopathologic examinations of tracheobronchial aspirates from 108 infants sampled during mechanical ventilation demonstrated a well-defined progression of cytologic changes in bronchial cells that could be divided into three classes. Seventy percent of infants with respiratory distress syndrome who developed bronchopulmonary dysplasia had pulmonary effluent cytology designated Class III; no infants with RDS but without BPD had these cytologic findings. Additionally, a temporal progression of events involving polymorphonuclear leukocyte and macrophage populations occurred in the absence of infection; these events were associated with duration of assisted ventilation and oxygen exposure. The technique described provides a useful way to monitor the progression of lung injury and repair and offers a cytologic method to predict and diagnose the development of bronchopulmonary dysplasia.

Bronchi↗
PubMed1981

Alterations in fetal lung phosphatidylinositol metabolism associated with maternal glucose intolerance.

Prior to conception, female rabbits were made hyperglycemic by streptozotocin administration. Fetal hyperglycemia and hyperinsulinemia were documented. Although plasma myoinositol concentration were higher in the fetuses of diabetic mothers, the ratio of lung to plasma myoinositol concentrations in 29-day fetal rabbits were lower than control values. CDP-diglyceride:inositol phosphatidyltransferase was reduced by 70% in the diabetic fetuses and their lung tissue phosphatidylinositol content was decreased.

Animals↗
PubMed1980

Effect of prolactin on phospholipid biosynthesis by alveolar cell carcinoma (A549) in monolayer tissue culture.

By means of an alveolar cell carcinoma (A549) model, the effect of prolactin on pulmonary surfactant phospholipid biosynthesis was investigated. Preliminary results suggest that phosphatidylcholine synthesis via the phosphatidic acid phosphohydrolase pathway in addition to phosphatidylglycerol may be stimulated by the presence of prolactin.

Adenocarcinoma, Bronchiolo-Alveolar↗
PubMed1980

Use of side-hole endotracheal tube adapter for tracheal aspiration. A controlled study.

An alternate tracheal aspiration procedure using a side-hole endotracheal adapter was used in conjunction with transcutaneous oxygen (TcPO2) monitoring in 13 mechanically ventilated newborn infants. Decline in TcPO2 during suctioning and drop in neonatal heart rate were both substantially reduced using a procedure designed to preserve mean airway pressure. When compared with the routine procedure of disconnecting the endotracheal tube from the ventilator and suctioning via an end-hold adapter, this approach prevented precipitous and dangerous hypoxemia.

Airway Resistance↗