Biomedical subjects
Publications and source records attributed to T F Yeh.
A loading dose of theophylline produces significant metabolic changes, including increase of plasma glucose concentration and an early rise in serum insulin in some infants. The chronic effects of theophylline on plasma glucose, serum insulin, and glucagon are not known at this time. The potential for development of metabolic derangements must be kept in mind when theophylline is used for protracted periods in premature infants.
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To provide a clinical assessment of cardiovascular dysfunction (CVD) in premature infants with patent ductus arteriosus (PDA), a scoring system (CVD score) was devised and correlated with blood gases, acid-base balance, and echocardiogram. The score consisted of evaluation of heart rate, quality of peripheral arterial pulsation, degree of precordial pulsation, duration of murmur and cardiothoracic ratio on chest roentgenogram. There were 116 observations made on 55 premature infants who had PDA and required medical or surgical treatment. Significant positive correlations were seen for CVD score with left atrial (LA)/aortic (Ao) ratio (p less than 0.001), left ventricular and diastolic dimension (DD) (p less than 0.001), blood pH (p less than 0.01), and blood PCO2 (p less than 0.01). The scoring system may by used as a clinical guide when echocardiogram or angiogram is not available.
In the course of a double-blind controlled study of intravenous indomethacin therapy in premature infants with patent ducts arteriosus (PDA), dynamic lung compliance (CL) was determined in 11 infants (six control, five indomethacin) who were not on assisted ventilation during the study period. The clinical, biochemical and laboratory data before the study were comparable between the groups. Following therapy with indomethacin there was a significant decrease in left atrial/aortic root ratio (LA/Ao), left ventricular end-diastolic dimension (LVEDD) on echocardiogram, and an increase in tidal volume (VT) and CL. In the control group, these variables did not change significantly. The improved lung compliance following early indomethacin closure of PDA may alter the clinical course and outcome of these premature infants.
In the course of a double-blind trial of intravenous indomethacin therapy in premature infants with patent ductus arteriosus, renal function and urinary kallikrein were studied in 21 infants following one dose of either saline placebo or indomethacin. Ten infants were assigned to the control group and 11 were in the indomethacin group. Significantly lower urine output, fraction excretion of sodium, fraction excretion of chloride, and urinary kallikrein were noted by 45%, 59%, 63%, and 51%, respectively, in the indomethacin group as compared to the control group. There was a concomitant decrease in serum sodium concentration (P less than .05) at 24 hours following indomethacin therapy. No significant difference in glomerular filtration rate was seen between the control group and the indomethacin-treated infants.
Fifteen studies were performed in ten premature infants whose birth weight (mean +/- SD) was 1,444 +/- 250 gm, gestational age 32.7 +/- 1.0 weeks, and postnatal age 10.7 +/- 3.3 days. Each study consisted of three hours simultaneous measurement of insensible water loss and oxygen consumption under two conditions for the same infant: (1) inside a single-walled incubator and (2) inside a double-walled incubator. The double-walled incubator provided significantly (P < 0.001) higher operative temperature and incubator wall temperature than did the single-walled incubator. Infants inside the double-walled incubator had significantly lower (P < 0.01) IWL (30% reduction) and lower (P < 0.05) VO2 (17% reduction) than inside the single-walled incubator--a net caloric saving of 11.8 kcal/kg/day. This saving of energy expenditure may be important in affecting the growth and outcome of the low-birth-weight infants.
We studied the pharmacokinetics of indomethacin (0.3 mg/kg) given intravenously in 17 premature infants to promote closure of persistent ductus arteriosus. The decay of indomethacin generally showed an initial rapid distribution (alpha) phase followed by a slower elimination (beta) phase. The mean half-life of elimination (20.7 +/- 8 hours) was three times longer, and the mean clearance rate (13 +/0 9.5 ml/kg/hour) was seven times less than that reported in adults. The indomethacin clearance rate was linearly correlated with postnatal age (r = 0.71, P < 0.01). There was strong evidence of later re-entry of indomethacin into the plasma, suggesting that enterohepatic recirculation may be common in premature infants and may contribute to the relatively long half-life of elimination. Our data do not clarify the question of target concentration or minimal exposure time above which permanent closure may occur, but the group of infants who had permanent PDA closure after only one dose (8/17) had a significantly higher plasma indomethacin concentration time integral than the group (9/17) who needed more than one dose (P < 0.01). A 24-hour dosage interval was often sufficient when an iv indomethacin bolus of 0.3 mg/kg was used but, below the age of nonresponsiveness to indomethacin, a shorter interval may be preferable as postnatal age increases.
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Aspiration of meconium produces respiratory distress of various severity and outcome. To evaluate whether the initial chest roentgenogram (0 to 8 hours of age) can be used to predict the outcome, an analysis of 80 cases with clinical and roentgenographic features of aspiration syndrome was undertaken. Infiltration was seen in 62, consolidation or atelectasis in 44, hyperinflation in 37, air leak in 25, pleural effusion in 16, and increased cardiothymic shadow in 16. Consolidation or atelectasis, most commonly associated with thick meconium aspiration, appeared to be the most significant determinant of poor outcome. Infants who had consolidation or atelectasis were more ill, had lower pH, higher fraction of inspired oxygen, higher alveolar-arterial oxygen gradients, and required longer duration of oxygen intake than those infants who had no consolidation or atelectasis. Thus, the initial chest roentgenogram can be used for predicting outcome in infants with meconium aspiration syndrome.
Nine infants less than 2 months of age with group B streptococcal (GBS) osteomyelitis or septic arthritis, or both, were seen from January 1975 through January 1978. The infants had local joint signs, usually in the absence of systemic signs. The bones and joints involved were equally distributed between proximal humerus and proximal and distal femur. An infant had involvement of the talus. Treatment consisted of two to three weeks of parenteral antibiotics, arthrotomy in infants with arthritis, and bone decompression in infants with osteomyelitis. Clinical follow-up showed normal growth and function of the affected joint. Of the organisms, five were typed: four were type III and one was type Ib. Group B streptococcal osteomyelitis and/or septic arthritis was the second most common late-onset GSB infection, being surpassed only by meningitis.
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A neonate with an infected omphalocele was treated locally with merbromin (mercurochrome) for five days. Extensive skin peeling with bullous lesions, edema, and fever developed three days after mercurochrome therapy. The infant died on the ninth day. Autopsy revealed evidence of heavy metal poisoning of the kidney, excessive mercury levels in the blood, and in tissues of the brain, kidney, and liver.
Nine infants with early-onset Haemophilus sepsis were seen between January 1973 and July 1977. Of the five isolated strains that were typed, only one was type B. All infants had respiratory distress, metabolic acidosis, and large alveolar-arterial oxygen tension difference gradients. Eight infants weighed less than 1,500 gm and died; one infant weighed 1,701 gm and survived. Roentgenograms in six of eight showed hyaline membrane disease. Pulmonary pathologic specimens in eight infants revealed hyaline membranes in six and polymorphonuclear leukocytes in the alveolar spaces in four. In two infants, small Gram-negative bacilli were noted within proteinaceous exudates in alveolar ducts. The route and time of infection in these infants with early-onset Haemophilus sepsis are unclear. However, the possibility that the infection occurs before birth and that these infants represent septically aborted prematures is suggested by the high incidence of prematurity in infants with early-onset Haemophilus sepsis and early detection of bacteremia in three infants.