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Biomedical subjects

S Baumgart

Publications and source records attributed to S Baumgart.

At least 19 recordsLinked to original sources
PubMed1992

Sodium restriction versus daily maintenance replacement in very low birth weight premature neonates: a randomized, blind therapeutic trial.

To test the hypothesis that restriction of sodium intake during the first 3 to 5 days of life will prevent the occurrence of hypernatremia and the need for administration of large fluid volumes, we prospectively and randomly assigned 17 babies (mean +/- SD: 850 +/- 120 gm; 27 +/- 1 weeks of gestation) to receive in blind fashion either daily maintenance sodium or salt restriction with physician-prescribed parenteral fluid intake. Maintenance-group infants received 3 to 4 mEq of sodium per kilogram per day; restricted infants received no sodium supplement other than with such treatments as transfusion. Sodium balance studies conducted for 5 days demonstrated that maintenance salt intake resulted in a daily sodium balance near zero, whereas sodium-restricted infants continued to excrete urinary sodium at a high rate, which promoted a more negative balance (average daily sodium balance -0.30 +/- 1.78 SD in maintenance group vs -3.71 +/- 1.47 mEq/kg per day in restriction group; p less than 0.001). Care givers tended to prescribe daily increases in parenteral fluids for the salt-supplemented infants, perhaps because serum sodium concentrations were elevated in these infants after the first day of the study (p less than 0.001). Hypernatremia developed in two sodium-supplemented infants (greater than 150 mEq/L), and hyponatremia developed in two sodium-restricted infants (less than 130 mEq/L); however, the restricted infants were more likely to have normal serum osmolality (p less than 0.05). Both groups of infants produced urine that was neither concentrated nor dilute, with a high fractional excretion of sodium; renal failure was not observed. The mortality rate was not affected, but the incidence of bronchopulmonary dysplasia was significantly less in the sodium-restricted babies (p less than 0.02). We conclude that in tiny premature infants, a fluid regimen that restricts sodium may simplify parenteral fluid therapy targeted to prevent hypernatremia and excessive administration of parenteral fluids.

Fluid Therapy↗
PubMed1992

Diagnosis-related criteria in the consideration of extracorporeal membrane oxygenation in neonates previously treated with high-frequency jet ventilation.

High-frequency jet ventilation (HFJV) is one of several high-frequency techniques that are particularly valuable for treating the neonate with lung disease refractory to conventional ventilation or with pulmonary air leak. Extracorporeal membrane oxygenation (ECMO) has also emerged as a valuable rescue therapy for neonates of more than 2000 g birth weight and 34 weeks' gestation with intractable respiratory failure. With the concurrent introduction of HFJV and ECMO, the authors sought to evaluate the role of HFJV prior to the institution of ECMO therapy. The data base for 2856 neonates receiving mechanical ventilation in one unit was used to identify 73 (of 298 total) neonates treated with HFJV, who were eligible by age and weight criteria for ECMO. Patients were grouped by diagnosis, and the oxygenation index (OI) was calculated during therapy. Outcome was evaluated for mortality, and the sensitivity of the OI for predicting mortality was calculated. Neonates who survived with HFJV alone presented with an OI of 0.30 +/- 0.03 (SEM), significantly less than nonsurvivors (0.42 +/- 0.04, P = .016). Survivors responded to HFJV with a rapid decrease in OI at 1 hour (0.19 +/- 0.02, P less than .001) and 6 hours (0.15 +/- 0.01, P less than .001). Nonsurvivors did not respond significantly at 1 hour (OI = 0.33 +/- 0.04, P = not significant [NS]) or at 6 hours (OI = 0.40 +/- 0.06, P = NS). By diagnosis, neonates with respiratory distress syndrome survived more often with HFJV (28/34, 82%) than neonates with meconium aspiration (10/26, 38%) or diaphragmatic hernia (3/9, 33%). Neonates with respiratory distress syndrome seldom presented with high OI values, but the majority of those who did survived (5/7 survived with initial OI greater than or equal to 0.40).(ABSTRACT TRUNCATED AT 250 WORDS)

Birth Weight↗
PubMed1991

Atrial natriuretic factor and postnatal diuresis in respiratory distress syndrome.

To find out if atrial natriuretic factor plays a part in the control of urine output during the initiation alone or throughout postnatal diuresis in neonates with respiratory distress syndrome, atrial natriuretic factor concentrations and clinical and renal variables were measured prospectively three times during the first three days of life in 13 premature infants. Atrial natriuretic factor concentrations rose significantly between the first and second sample times as did the urine output and output:input ratio. By the time that the third sample was taken, atrial natriuretic factor concentration had decreased significantly since the second sample had been taken, while urine flow was maintained. All subjects initiated a spontaneous diuresis that was related to the second concentration of atrial natriuretic factor. With partial correlation analysis a significant relationship was shown between the concentration of atrial natriuretic factor and the maintenance of urine output throughout the study period. Individual hormone concentrations did not, however, correlate with simultaneous renal variables. Changes in the concentrations of atrial natriuretic factor coincided with initiation of spontaneous diuresis in babies with respiratory distress syndrome, and may have a role in the complex mechanisms that maintain this diuresis.

Atrial Natriuretic Factor↗
PubMed1990

Accurate, noninvasive quantitation of expiratory gas leak from uncuffed infant endotracheal tubes.

Accurate measurement of expiratory gas leak from uncuffed infant endotracheal tubes is an important requirement for evaluating the rates of metabolic gas exchange by indirect calorimetry in neonates receiving mechanical ventilation. The present study reports a new, noninvasive technique for the efficient collection and analysis of expiratory gases leaked from a closed-circuit metabolic monitoring system recently described. A loose-fitting face mask is placed over the infant's endotracheal appliance and air is entrained from the mask cavity at 100 mL/min for CO2 analysis by infrared capnometry. In vitro calibration of this apparatus demonstrates a relative error of less than 5% of simulated endotracheal tube leak. In vivo application to metabolic rate assessment (using the MGM Jr. metabolic cart) in 12 intubated, ventilated infants ranging from 1.56 to 4.07 kg study weight demonstrated endotracheal tube leaks from 0.49 to 7.40% of net CO2 production, which ranged 10.67 to 70.91 mL/min (or mean 8.22 +/- 0.93 SEM mL/kg/min). The magnitude of tube leakage of mixed expiratory gases could not be predicted from endotracheal tube diameter, ventilator settings, or infant activity or posture. As new instrumentation becomes available to measure the rates of metabolic gas exchange in intubated infants, systematic evaluation of uncuffed endotracheal tube gas leaks becomes critical.

Calorimetry↗
PubMed1990

Radiant heat loss versus radiant heat gain in premature neonates under radiant warmers.

Premature infants nursed on open radiant warmer beds are exposed to short-wavelength infrared power density distributed evenly over the bed surface. Additionally, infants' sides are exposed to relatively cooler nursery walls, and to the radiant warmer bed platform which may heat and reradiate to the baby. Therefore, infants may not only gain heat from the warmer (Q radiant warmer) but lose or gain radiant heat to the sides as well (+/- Q radiant loss). In order to quantitate these parameters, ten premature newborn infants nursed under radiant warmers servocontrolled to 36.5 degrees C skin temperature (weight 1.27 +/- 0.24 SD kg, gestation 31 +/- 3 weeks) were investigated, and partitional calorimetry previously reported. In the present study, calculation of net rate of radiant heat transfer (Q net radiant) was made from these data (-2.63 +/- -1.52 kcal/kg/h), and compared to direct measurements of Q radiant warmer (-2.49 +/- -0.90 kcal/kg/h). The present report further partitions net radiant heat transfer to evaluate Q radiant loss: -0.13 +/- 1.82 kcal/kg/h (range -3.16 to 1.93). From these calculations mean radiant temperature of this environment was estimated (45.3 +/- 4.3 degrees C) and compared to the radiant warmer temperature received (45.0 +/- 2.9 degrees C). This information suggests other strategies to reduce radiant heat loss as well as convective and evaporative losses in premature neonates nursed on open radiant warmer beds.

Body Temperature Regulation↗
PubMed1990

Distinguishing sepsis from blood culture contamination in young infants with blood cultures growing coagulase-negative staphylococci.

In the ideal situation, the evaluation for sepsis in the young infant should include collection of multiple blood cultures before the institution of antibiotics. Unfortunately, in some infants, it may not be possible to obtain more than a single blood culture at the time of initial evaluation. If this single culture ultimately grows coagulase-negative staphylococci and the infant has been treated with antimicrobial therapy in the interim, it is often difficult to determine whether the positive culture represents true infection or contamination. Our data suggest that peripheral blood cultures yielding high colony counts most likely represent infection. Furthermore, in this high-risk patient population, low colony-count growth should not be ignored as contamination, particularly if there are significant clinical findings or if the infant has a central catheter or hematologic abnormality. Future studies should examine these important issues.

Blood Specimen Collection↗
PubMed1989

Neonatal Staphylococcus epidermidis meningitis with unremarkable CSF examination results.

We identified 10 infants (mean +/- SD birth weight, 1000 +/- 500 g; gestation, 29 +/- 3 weeks; postnatal age, 24 +/- 19 days) who had Staphylococcus epidermidis meningitis despite unremarkable cerebrospinal fluid (CSF) blood cell counts and glucose and protein levels. Staphylococcus epidermidis meningitis was diagnosed if all the following criteria were satisfied: (1) a CSF culture positive for S epidermidis within 48 hours, (2) a blood culture positive for S epidermidis with antibiotic sensitivities identical to those of the CSF isolate, and (3) clinical symptomatology. Lumbar puncture yielded white blood cell counts lower than 10 x 10(6)/L in 8 infants. Two subjects had CSF white blood cell counts of 11 x 10(6)/L and 14 x 10(6)/L. Cerebrospinal fluid glucose (2.8 +/- 0.9 mmol/L) and protein (1.15 +/- 0.32 g/L) concentrations were also unremarkable. Infants were treated with parenteral antibiotics for 19 +/- 5 days. There was no mortality or short-term morbidity. Staphylococcus epidermidis is a recognized cause of nosocomial meningitis in low-birth-weight infants and frequently occurs without CSF abnormalities.

Cerebrospinal Fluid Proteins↗
PubMed1989

Surface colonization with coagulase-negative staphylococci in premature neonates.

To follow the emergence of surface colonization with coagulase-negative staphylococci in neonates, we sampled four surface sites (axilla, ear, nasopharynx, and rectum) in 18 premature infants during the first 4 weeks of life. Swabs were obtained on the first day of life, twice weekly for 2 weeks, and weekly thereafter. Isolates were characterized by species, biotype, antibiotic susceptibility patterns, and slime production. Over 4 weeks the percentage of infants with Staphylococcus epidermidis as the only surface coagulase-negative staphylococci rose from 11% to 100%. Predominance of a single S. epidermidis biotype increased from none to 89%. Multiple antibiotic resistance rose from 32% to 82% of isolates, and the prevalence of slime production increased from 68% to 95%. This microbiologic pattern was established by the end of the first week of life and persisted throughout the month of study. In three infants, S. epidermidis sepsis developed with organisms identical to their predominant surface isolate. We conclude that species, multiple antibiotic resistance, and slime production appear to confer a selective advantage for the surface colonization of premature newborn infants in the intensive care nursery environment. Infants so colonized may be at greater risk for subsequent infection with these strains of coagulase-negative staphylococci.

Age Factors↗
PubMed1989

Semipermeable polyurethane membrane as an artificial skin for the premature neonate.

A thin and semipermeable polyurethane membrane adherently applied to premature neonates as an artificial skin was investigated as an atraumatic surface barrier sufficient to reduce transepidermal water loss without inhibiting natural infant skin development during the first few days of life. A sample group of 18 neonates (birth weight [mean +/- SEM] 1.39 +/- 0.12 kg, gestation [mean +/- SEM] 31 +/- 1 weeks) received two 3 X 3-cm polyurethane patches adherent over the chest and abdomen. Transepidermal water loss was measured before and after application and after membrane removal. During longitudinal study, seven infants were treated day 1 through day 4 of life and were evaluated for skin integrity 24 hours after patch removal on day 5. Polyurethane membranes produced an acute and significant reduction in transepidermal water loss for the 18 subjects: 21.1 +/- 2.0 g/m2/h before application v 10.5 +/- 1.4 g/m2/h with membranes in place (P less than .001). Immediately after patch removal, transepidermal loss returned to 22.8 +/- 3.0 g/m2/h. Throughout the first four days of life, daily measurements of water loss were significantly less: 53% to as much as 72% reduction from polyurethane-covered sites when compared with adjacent naked skin. After polyurethane membrane removal, skin development of transepidermal barrier function was comparable over both sites. Dressings did not lose adhesive or plastic properties during an extended time in either radiant warmer or incubator environments, electronic monitoring through membranes was not impeded, and adhesive injuries were not observed. An adherent, semipermeable polyurethane membrane may be effective as an atraumatic artificial barrier to prevent large transepidermal water loss and protect the skin of the premature neonate.

Body Temperature Regulation↗
PubMed1988

Continuous intracranial pressure monitoring and serial electroencephalographic recordings in severely asphyxiated term neonates.

We report our observations from intensive intracranial pressure (ICP) monitoring and serial clinical neurologic and electroencephalographic examinations in ten asphyxiated full-term neonates, of whom five died and at least two survivors had multiple severe neurologic handicaps. Direct measurements of ICP were obtained by a newly developed infant subarachnoid bolt and/or a transfontanelle pressure transducer. Simultaneous ICPs were recorded and correlated when possible. We noted a dependence of transfontanelle ICP values on application technique and force. In infants with no bleeding diathesis, the subarachnoid bolt was safe and no complications were encountered. Only six infants experienced pathologic elevations of ICP following birth asphyxia, and of these infants only two had sustained, marked increases of ICP. We also noted abundant fluctuations of cerebral perfusion pressure (mean arterial blood pressure minus ICP), but the majority of fluctuations were accounted for by mean arterial pressure changes rather than ICP changes. We found no deterioration of clinical neurologic function as measured by serial mental status examinations and electroencephalogram samples at the time the maximum ICP was measured. We also noted very little change in ICP during most electrographic seizures. In these infants ICP did increase after birth but major ICP elevations were uncommon and did not appear to introduce any acute functional neurologic disturbances. Most changes in cerebral perfusion pressure were attributed to blood pressure rather than ICP changes. It appears unlikely that cerebral edema and elevated ICP play a major role in determining neurologic outcome in some asphyxiated term infants.

Asphyxia Neonatorum↗
PubMed1988

Nonoliguric hyperkalemia in the premature infant weighing less than 1000 grams.

Eighteen very low birth weight premature infants born before 28 weeks gestation and weighing less than 1000 gm were evaluated prospectively for disturbances in serum electrolyte concentrations and for renal glomerular and tubular functions. Clinically symptomatic hyperkalemia resulting in significant electrocardiographic dysrhythmias developed in eight of these infants; 10 babies remained normokalemic. Peak serum potassium concentration ranged from 6.9 to 9.2 mEq/L in the hyperkalemic group; all potassium values in the normokalemic group were less than 6.6 mEq/L. Indices of renal glomerular function and urine output were similar in both groups; no infant had oliguria. Serum creatinine concentrations were the same in both groups (1.04 +/- 0.16 SD mg/dl in normokalemic vs 1.19 +/- 0.24 mg/dl in hyperkalemic infants, beta less than 0.2 at alpha = 0.05), and glomerular filtration rates did not differ significantly (6.29 +/- 1.78 ml/min/1.73 m2 in normokalemic vs 5.70 +/- 1.94 ml/min/1.73 m2 in hyperkalemic infants, beta less than 0.2 at alpha = 0.05). In contrast, indicators of tubular function revealed a significantly larger fractional excretion of sodium in hyperkalemic infants: 13.9 +/- 5.4% versus 5.6 +/- 0.9% in normokalemic control subjects (p less than 0.001). Hyperkalemic infants also had a tendency toward lower urine concentrations of potassium, although there was no significant difference in their net potassium excretion in comparison with that in the normokalemic group. We speculate that hyperkalemia in the tiny baby is in part the result of immature distal tubule function with a compromise in ability to regulate potassium balance.

Humans↗
PubMed1987

Impaired sensitivity of a single early leukocyte count in screening for neonatal sepsis.

The common clinical practice of using a single, early white blood cell (WBC) count to screen for early onset neonatal sepsis was investigated in a population of 61 newborn infants with culture proven sepsis in the first 3 days of life. Thirteen patients (21%) had a falsely normal WBC screening test. The patients with true positive and falsely normal WBC counts did not differ by risk factors for sepsis, birth weight, age, outcome or severity of disease. However, there was a significant delay between the screening test and the positive blood culture in the patients with false normal WBC counts and not in the patients with positive abnormal WBC counts (14.9 +/- 5.9 hours vs. 2.8 +/- 1.4 hr, mean +/- SE, P less than 0.001). A WBC count obtained soon after birth as currently utilized may not adequately screen for early onset neonatal sepsis.

False Negative Reactions↗
PubMed1987

Optimal thermal management for low birth weight infants nursed under high-powered radiant warmers.

Servocontrol of skin temperature for the critically ill premature neonate nursed on a radiant warmer bed has been assumed to be analogous to skin temperature control for infants nursed in convection-warmed incubators. There are significant differences between these two warming techniques, and no definitive data exist to aid the clinical specialist in governing radiant warmer control. Eighteen low birth weight premature infants less than 2 weeks of age were studied under powerful overhead radiant warmers to determine the optimal skin temperature for servocontrol of radiant heater output. Anterior abdominal wall temperature was servocontrolled at 35.5 degrees, 36.5 degrees, and 37.5 degrees C in a randomized fashion for three periods of 90 minutes each after thermal equilibrium was established. Oxygen consumption was measured during the entire 90-min sample period at each temperature by a computerized metabolic apparatus to determine the optimal thermal neutral control temperature defined as minimal oxygen consumption with normal body temperature. Skin, deep rectal, and environmental temperature measurements, as well as behavior assessments, were made concurrently. Oxygen consumption was significantly elevated at 35.5 degrees C (8.62 +/- 0.73 mL/kg/min, mean +/- SEM) compared with 36.5 degrees C (7.30 +/- 0.55 mL/kg/min). Changing servocontrol temperature to 37.5 degrees C produced no further significant decrease in oxygen consumption (7.41 +/- 0.70 mL/kg/min), and nine infants manifested supranormal deep rectal temperatures (greater than 37.5 degrees C). Optimal abdominal skin temperature control at 36.5 degrees C (slightly warmer than previously reported but less than 37.5 degrees C) is recommended for premature neonates nursed on radiant warmer beds.(ABSTRACT TRUNCATED AT 250 WORDS)

Beds↗
PubMed1986

Staphylococcus epidermidis-associated enterocolitis.

Nineteen infants (mean +/- SD gestational age 30 +/- 2 weeks, birth weight 1.28 +/- 0.53 kg) with Staphylococcus epidermidis bacteremia were found on retrospective chart review to have had signs and symptoms of acute enterocolitis. This S. epidermidis-associated enterocolitis constituted 37% of the 51 cases of enterocolitis and 23% of the 81 cases of S. epidermidis sepsis during the study period. S. epidermidis-associated enterocolitis was relatively mild compared with other forms of enterocolitis. Although abdominal radiographs showed markedly abnormal bowel gas patterns with distended bowel loops and bowel wall edema, only one infant had pneumatosis intestinalis and none had portal venous or free intraperitoneal gas. Only three infants had neutropenia, and five had thrombocytopenia. None of these infants required surgical intervention. Although bloody stools often persisted for weeks, none of the neonates had prolonged feeding intolerance or development of a stricture. We conclude that S. epidermidis infection is commonly associated with a mild form of enterocolitis in the neonate and that this association should be considered when selecting antibiotics for therapy.

Enterocolitis↗
PubMed1986

Modern fluid and electrolyte management of the critically ill premature infant.

In this article, the authors introduce the concept of a transitional physiology which governs fluid and electrolyte balance in the immediate postnatal period. The important impact of the extrauterine environment on fluid balance is also discussed. Finally, the pathophysiology of diuresis in RDS, and fluid shifts in the VLBW infant with therapeutic recommendations are presented.

Body Water↗
PubMed1986

Inductive plethysmography--a facilitated postural calibration technique for rapid and accurate tidal volume determination in low birth weight premature newborns.

Inductive plethysmography is a noninvasive method of measuring lung volumes in infants. This technique, however, has had very limited use in premature newborns because of the difficulty of calibrating the device with regard to the small tidal volumes (VT) in such infants. The present study describes a facilitated calibration of the inductive plethysmograph in low birth weight infants. The technique depends on generating significantly different compartmentalization of VT into rib cage and abdominal components by changing the infant's position from supine to upright. Linear regression analyses were performed to compare VT measurements made in 9 premature infants with the inductive plethysmograph and the pneumotachygraph; an overall Z-transformed correlation of 501 breath-to-breath comparisons yielded an r value of 0.80; the mean VT (pneumotachygraph) was 13.9 +/- 4.7 ml SD; the mean VT (inductive plethysmograph) was 14.3 +/- 5.1 ml SD. It is concluded that inductive plethysmography is an accurate method to measure VT in small premature infants. Moreover, the ease of the two-position technique for calibration of the device gives the inductive plethysmograph greater utility as a clinical and research tool for measuring lung volumes in premature infants.

Calibration↗