Search PubMed⌕ Search

Biomedical subjects

K H Marks

Publications and source records attributed to K H Marks.

33 records · Page 2Linked to original sources
PubMed1981

The metabolic effects of caffeine in the newborn infant.

We studied the effects of intravenous administration of 20 mg/kg caffeine citrate on glucose homeostasis, cardiorespiratory status, and urinary excretion of catecholamines and electrolytes in 12 premature infants with recurrent apnea. Six infants received intravenous dextrose (5% or 10% in 0.225% saline) during the study, and six were fed formula every 3-4 hours. In the intravenously fed infants, the plasma glucose concentration postcaffeine did not vary significantly from the precaffeine level of 73 +/- 3.2 mg/dl (mean +/- SEM) at 0.5, 1, and 1.5 hours. However, in the formula-fed infants, there was a consistent fall in plasma glucose levels after caffeine administration. This decrease from a precaffeine level of 99 +/- 12 mg/dl (mean +/- SEM) approached statistical significance at 0.5 hours (P = 0.07), and was significantly lower at 1 and 1.5 hours (P less than 0.02). In five infants, cardiorespiratory status and urinary excretion of catecholamines and electrolytes were evaluated for 12-hour periods before and after caffeine administration. There was a significant reduction in the number of apneic episodes following caffeine administration; however, caffeine did not appear to affect mean heart rate or urinary excretion of sodium, potassium, epinephrine, norepinephrine, or dopamine. Our data suggest that the effects of caffeine on glucose homeostasis may vary with the nature and/or route of substrate administration.

Apnea↗
PubMed1981

Understanding the Pleurevac.

The infant nonmetered Pleurevac was studied under laboratory conditions. Evacuation of a spirometer was measured at various negative pressures through the infant thoracostomy tubes routinely used in the clinical setting. In addition, a tension pneumothorax model was designed, and factors affecting its evacuation rate were studied. In accordance with Poiseuille's law, the evacuation rate was proportional to the negative pressure applied to the thoracostomy tube, and the radius of the tube. The airflow rate (bubble rate) through the Pleurevac was found to be of minor importance in affecting evacuation.

Evaluation Studies as Topic↗
PubMed1981

Oxygen consumption and temperature control of premature infants in a double-wall incubator.

The effects of a double wall in a forced convection-heated incubator were studied on ten naked, nondistressed, premature infants by measuring their mean skin temperature, esophageal temperature, and oxygen consumption when they were in thermal steady state, with, and without, the double wall in place. The incubator air temperature was maintained within the recommended thermoneutral zone during the consecutive paired experiments. Ambient room temperature and relative humidity were constant and the infant's activity (quiet sleep) and postprandial state were the same in both conditions. Together with a significant rise in operative temperature (P less than .05) induced by the double wall (accounted for by a 0.9 C mean increased in incubator wall temperature nearest the baby), their mean skin temperature and esophageal temperatures increased (P less than .025), while a decrease in oxygen consumption occurred in nine of the ten infants (P less than .05). These findings suggest that the double wall reduced radiant and total heat loss from the baby by diminishing the temperature gradient between the skin and incubator surfaces and that metabolic heat production (oxygen consumption) was reduced when the double wall was in place.

Body Temperature↗
PubMed1980

Oxygen consumption and insensible water loss in premature infants under radiant heaters.

Oxygen consumption ((Vo2), carbon dioxide production (Vco2), and insensible water loss (IWL) were measured simultaneously in nine nondistressed, appropriately grown, premature infants less than 2 weeks old, nursed in a conventional, blow-warmed incubator, and were compared with measurements made on the same infants under a radiant heater. The infants had a pronounced increase (148% on average) in IWL when under the radiant heater (P < .001) whereas Vo2 increased by only 4.6% (P = .073). Abdominal skin temperature (servocontrolled to maintain 36.5 C) and esophageal temperature were the same under both conditions, but ambient air temperature was 0.7 C higher in the incubator (P < 05). Although a positive correlation was found between the increase in IWL and the change in Vo2 (r = .75, P < .01), the large increase in IWL (and, therefore, evaporative heat loss) under the radiant heater is out of proportion to, and cannot be accounted for, by the change in metabolic heat production. The heat transfer processes involved in maintaining body temperature constant under these conditions require further study.

Body Temperature Regulation↗
PubMed1979

Head growth in sick premature infants--a longitudinal study.

Serial weekly measurements of somatic growth and head circumference were made for ten weeks on 41 appropriately grown sick preterm infants (gestational age 28 to 32 weeks) with severe neonatal problems. Twenty-seven (66%) required prolonged assisted ventilation. During the period of acute illness, the velocity of growth for the sick infants was below that of the normal fetus, with deviation away from and below the normal fetal growth curve. During recovery, head growth paralleled that of normal fetal growth, and subsequently rapid "catch-up" growth in head circumference occurred. By comparison, six similar infants, whose head circumference followed the intrauterine growth curve, proved to have hydrocephalus. These results suggest that: (1) the brain participates in the growth retardation associated with being sick and premature and that apparently normal head growth under comparable circumstances may be associated with hydrocephalus; (2) in spite of an energy intake ranging from 80 to 120 kcal/kg/day by the end of the second postpartum week, normal growth in the sick low-birth-weight infant does not occur until their acute illness has resolved.

Female↗
PubMed1979

Intravenous alimentation and insensible water loss in low-birth-weight infants.

Insensible water loss (IWL) was measured in six premature infants, between 4 and 21 days of age, by continuous weight monitoring on an electronic balance inside an incubator. Multiple measurements of IWL were made during the sequential infusion of 10% dextrose in 0.225% NaCl, 10% dextrose-amino acid solution, or 10% dextrose-amino acid and a commercial intravenous fat emulsion. Each solution was administered for three hours by constant infusion through a scalp vein needle. The order of the infusion was random and a 30- to 60-minute infusion with 5% dextrose water was given between each solution. During the infusion of 10% dextrose in 0.225% NaCl and 10% dextrose + amino acid solution, IWL was 1.0 +/- 0.8 gm/kg/hr and 1.1 +/- 0.8 gm/kg/hr, respectively. In contrast, IWL increased significantly to 1.6 +/- 0.7 gm/kg/hr when additional calories were given using the 10% dextrose-amino acid with the intravenous fat emulsion (P less than .005). There was a positive correlation between calorie intake and IWL. These data suggest that parenteral nutrition solutions with intravenous fat emulsion are rapidly metabolized and the increase in IWL is probably secondary to an increase in thermogenesis.

Enterocolitis, Pseudomembranous↗
PubMed1978

Urinary excretion of prostaglandin E following the administration of furosemide and indomethacin to sick low-birth-weight infants.

Urinary excretion of prostaglandin E was measured in seven sick low-birth-weight infants. Four had severe hyaline membrane disease and one had chronic bronchopulmonary dysplasia; all received furosemide. Two infants had patent ductus arteriosus and received indomethacin. Following administration of furosemide, urine volume and the excretion rates of sodium and calcium were significantly increased; such changes were not seen following the administration of indomethacin. Prostaglandin E excretion rate was increased from 0.4 +/- 0.04 to 1.3 +/- 0.2 ng/mg Cr (mean +/- SEM) following administration of furosemide, but decreased in two patients following administration of indomethacin. The present results demonstrate that furosemide enhances urinary excretion of prostaglandin E by mechanisms which may reflect an increase in prostaglandin synthesis, a decrease in prostaglandin renal metabolism, or both. Indomethacin, which is a prostaglandin synthetase inhibitor, decreases the urinary excretion of prostaglandin E. These observations suggest that furosemide therapy in patients receiving indomethacin may be ineffective.

Calcium↗
PubMed1978

Furosemide in hyaline membrane disease.

In a randomized clinical trial designed to evaluate the effect of diuresis on infants with hyaline membrane disease, seven infants were treated with furosemide (2 mg/kg intravenously) and five received 5% dextrose water in 0.225% sodium chloride (control group). Arterial blood gas analyses performed before and during the six hours after treatment showed no significant difference between control and treated infants. Urine output and urine sodium and calcium loss were significantly increased (P less than .05) in the infants receiving furosemide. The diuresis seemed to have no effect on left atrial size determined echocardiographically, whereas measurements of dynamic skinfold thickness suggested mobilization of subcutaneous water. One infant became seriously dehydrated and hypotensive secondary to a massive diuresis. We concluded that furosemide had a potent diuretic effect in infants with hyaline membrane disease but does not improve cardiorespiratory function acutely. This may be because of failure to mobilize pulmonary interstitial fluid in the time period tested. It may also be possible that the presence of pulmonary interstitial fluid does not play an important role in the impairment of gas exchange in the acute stage of hyaline membrane disease.

Carbon Dioxide↗
PubMed1978

Effect of parenteral fat emulsion on the pulmonary and reticuloendothelial systems in the newborn infant.

Analysis of phospholipids (PL), cholesterol esters, triglycerides (TG), and free fatty acids (FFA) was performed on plasma and RBCs in two sick low-birth-weight infants who received total parenteral nutrition including Intralipid for the first 9 and 12 weeks of life, respectively. There was an increase in the total concentration of the plasma IG and FFA in the infants receiving Intralipid as compared with controls. These elevated lipid levels were not detected by visual inspection of the plasma. When compared with control infants, higher levels of linoleic acid were found in the plasma and RBCs of infants receiving Intralipid while plasma PL contained less arachidonate. Histological examination of the lung in both infants who received Intralipid revealed numerous globules of sudanophilic material in alveolar macrophages and capillaries. There is a possibility that prolonged administration of Intralipid may be associated with altered pulmonary and reticuloendothelial system function.

Cholesterol Esters↗
PubMed1977

A simple device for reducing insensible water loss in low-birth-weight infants.

Insensible water loss (IWL) was measured in five premature infants, 1 to 4 days old, by multiple weighings on an electronic balance inside an incubator. The babies were studied naked before and after being covered with a transparent thermal blanket. The use of the thermal blanket produced a mean reduction of 70% in IWL and a net caloric saving of 27 kcal/kg/day. There was minimal interference with nursing care. The important caloric saving achieved from reduced vaporization of water and evaporative heat loss may be an important determinant of intact survival in the high-risk infant.

Bedding and Linens↗
PubMed1976

Correction of essential fatty acid deficiency in newborn infants by cutaneous application of sunflower-seed oil.

Two newborn infants receiving long-term, fat-free parenteral nutrition developed essential fatty acid (EFA) deficiency. Biochemical evidence of EFA deficiency was documented in plasma, red blood cells, and adipose tissue and included a decrease in arachidonic and linoleic acids, an increase in 5,8,11-eicosatrienoic acid, palmitoleic and oleic acids and a trienoic/tetraenoic ratio of more than 0.4. Cutaneous application of sunflower-seed oil, a source rich in the essential fat linoleic acid, rapidly reversed the clinical and biochemical manifestations of deficiency in plasma.

Adipose Tissue↗
PubMedDate not supplied

Indomethacin disposition and indomethacin-induced platelet dysfunction in premature infants.

Indomethacin failed to produce permanent ductal closure in any of four premature infants with patent ductus arteriosus to whom the drug was given. Indomethacin half-lives measured in two premature infants were 21 and 24 hours, respectively, much longer than in full-term newborns or adults. Platelet function, as measured by platelet aggregation, was grossly abnormal for two to four days after indomethacin administration, normal values returning only by the ninth and tenth days. Gastrointestinal bleeding and transient renal dysfunction occurred in one infant. Measurement of plasma indomethacin concentrations in sick, low-birthweight infants could help guide indomethacin dose and dosage interval, prevent drug accumulation, and reduce toxicity. Further studies of potential toxicity seem to be indicated before instituting widespread indomethacin administration for ductal closure in premature infants.

Blood Platelet Disorders↗