Search PubMed⌕ Search

Biomedical subjects

A Okken

Publications and source records attributed to A Okken.

At least 55 records · Page 3Linked to original sources
PubMed1993

Distribution of exogenous surfactant in rabbits with severe respiratory failure: the effect of volume.

The transient effect of surfactant therapy that is observed in some patients might, at least in part, be explained by a nonhomogeneous distribution. Therefore, we investigated the distribution of a surfactant preparation (Alvofact, 45 g/L) that is used clinically. Rabbits with severe respiratory failure were treated with this surfactant at a dose of 100 mg/kg body weight, and the distribution of surfactant was determined by the use of 141Ce-labeled microspheres that were mixed with the surfactant. Fifteen min after surfactant administration, the rabbits were killed, and the lungs were removed and divided into 200 pieces. The radioactivity per mg lung tissue was determined in each piece. We found that the endotracheal instillation of this surfactant preparation results in a nonhomogeneous distribution. However, a significantly improved distribution was obtained when this dose of surfactant (100 mg/kg body weight) was diluted with normal saline to a concentration of 6.25 g/L. The consequence of the administration of this dose was an intratracheal fluid administration of 16.0 mL/kg body weight. The distribution was also nonhomogeneous after the administration of a small-volume (2.4 mL/kg body weight), low-concentration surfactant preparation (6.25 g/L). We conclude that a surfactant preparation with clinical application is distributed nonhomogeneously in the lungs after endotracheal administration. The distribution can be significantly improved by increasing the fluid volume in which the surfactant is suspended.

Animals↗
PubMed1993

Postnatal glucose kinetics in newborns of tightly controlled insulin-dependent diabetic mothers.

Infants of diabetic mothers are at risk of developing hypoglycemia postnatally. Strict control of blood glucose during pregnancy might result in adequate glucose homeostasis in the neonate. We followed 15 mother-infant pairs from the beginning of pregnancy until birth. Glucose kinetics in the infants were measured on the first day of life, using a stable isotope dilution technique. Furthermore, levels of alternative substrates, FFA, and ketone bodies were measured. All infants received i.v. glucose from birth onward at a rate of 3.4 +/- 0.7 mg/kg/min (mean +/- SD). There was no relationship between the parameters of control of the insulin-dependent diabetes mellitus in the mothers and glucose kinetics in their infants. Glucose turnover was 5.2 +/- 1.1 mg/kg/min, glucose production rate (GPR) was 1.8 +/- 1.1 mg/kg/min. GPR was significantly lower in the infants studied at the end of the first day of life (p < 0.01), irrespective of the glucose infusion rate. Furthermore, the lower GPR was associated with an increased concentration of ketone bodies, suggesting an increased production of ketone bodies in these infants. The relatively high GPR measured in the infants who were studied in the first hours postnatally may be the result of postnatal hormonal stimulation of glycogenolysis and/or gluconeogenesis. From this study, we conclude that glucose kinetics in infants of tightly controlled diabetic mothers appear to be normal. Interestingly, despite the near-optimal insulin therapy in the mothers, there is a relationship between the SD scores of birth weight and the mean 3rd-trimester blood glucose values.

Aging↗
PubMed1992

Measurement of total bodywater volume with deuterated water in newborn infants.

D2O and H2(18)O are often used as tracers for the determination of total body water (TBW). For newborn infants, the commonly used noninvasive method has not been validated. In this study TBW was calculated from D2O concentrations in blood and compared with TBW calculated from D2O concentrations in urine. TBW calculated from all urine portions voided at least 6 h after D2O administration on average was 1.0% lower. TBW calculated from only three urine portions voided 6, 12, and 24 h after D2O administration was 0.6% (mean) lower compared to TBW calculated from D2O concentrations in blood. This study indicates that the noninvasive method to measure TBW can be considered a reliable method when used in newborn infants.

Body Water↗
PubMed1991

Fat absorption in neonates: comparison of long-chain-fatty-acid and triglyceride compositions of formula, feces, and blood.

We studied malabsorption of fat in neonates who were fed either a lard-modified formula (n = 22, gestational age, 33.6 +/- 3.9 wk) or an unmodified formula (n = 14, gestational age, 34.1 +/- 3.7 wk). In both groups fecal lipid consisted almost completely (greater than 90%) of free fatty acids, whose composition was highly correlated with the corresponding formula's fatty acid composition [r = 0.96 (lard modified) and r = 0.99 (standard)]. Both groups had similar relative amounts and compositions of fecal cholesterol esters and triglycerides. Plasma and, to a lesser extent, erythrocyte membrane long-chain-fatty-acid compositions correlated with those of the corresponding formulas. We suggest that the extensive intestinal hydrolysis and limited absorption of dietary lipids is, at least partly, due to lipolysis in the colon. Appearance of triglycerides in the colon may be due to a rapid small-intestinal passage in relation to small-intestinal lipolysis.

Chromatography, Gas↗
PubMed1991

Distribution of endotracheally instilled surfactant protein SP-C in lung-lavaged rabbits.

In lung-lavaged surfactant-deficient rabbits (n = 6) requiring artificial ventilation, porcine surfactant was instilled endotracheally. This resulted in improvement of lung function so that the animals could be weaned off artificial ventilation. The animals were killed 4 1/2 h after surfactant administration and the porcine surfactant protein was localized in the lung with a MAb. We found surfactant protein in all lobes of the lung but the distribution was not homogeneous. Surfactant protein C was found in less than 15% of the alveolar spaces and in less than 1% of the bronchi.

Animals↗
PubMed1990

[Risks of diazepam in newborn infants].

In children there is a good effect of diazepam on convulsions after intravenous or rectal administration. This is not the case in neonates. We describe a newborn to whom diazepam was given because of a convulsion and who exhibited serious side effects: coma, hypotonia and feeding difficulties. We point out the risks of using diazepam in neonates.

Asphyxia Neonatorum↗
PubMed1990

Incidence of forearm and hand ischaemia related to radial artery cannulation in newborn infants.

We report the incidence of transient and permanent ischaemia of the forearm and hand caused by radial artery cannulation in a series of 98 newborn infants. Birth weight ranged from 550 to 3920 g (median 1600 g) and gestational age ranged from 26 to 40 weeks (median 31 weeks). In 4 of the 98 infants transient ischaemia of the forearm and/or hand occurred. In three infants the onset of ischaemia was probably related to thrombo-embolic events and in one infant to inadequate palmar collateral circulation. Permanent ischaemic damage with tissue loss did not occur in any infant. It is concluded that permanent ischaemic damage to the forearm and/or the hand with tissue loss, attributable to radial artery cannulation, is seldom encountered in newborn infants. In minimizing the risk of ischaemia, careful assessment of palmar collateral circulation prior to cannulation and of all factors predisposing to the onset of ischaemia is essential. Immediate removal of the catheter at the earliest signs of ischaemia, is essential to prevent ensuing tissue loss.

Catheterization, Peripheral↗
PubMed1990

Incidence and duration of total occlusion of the radial artery in newborn infants after catheter removal.

The incidence and duration of total occlusion of the radial artery after catheter removal was determined using repeated Doppler flow measurements. Thirty-two newborn infants with birthweights ranging from 945 g to 3890 g (median 1935 g) and gestational age ranging from 26 to 40 weeks (median 32 weeks) were studied. In 20 out of 32 infants (63%), complete occlusion of the radial artery occurred. The number of occlusions were not related to birthweight, gestational age or duration of cannulation. In all infants, blood flow in the radial artery resumed within 1-29 days after catheter removal. The duration of occlusion was directly related to the duration of cannulation and inversely related to birthweight. This study demonstrates a high frequency of total occlusion of the radial artery in newborn infants after percutaneous radial artery cannulation. In the majority of infants with a radial artery catheter, blood flow to the tissue distal to the cannulation site is dependent solely on the existence of an adequate arterial palmar collateral circulation.

Arm↗
PubMed1990

Accurate measurement of intraarterial pressure through radial artery catheters in neonates.

A technique is described for accurate measurement of intraarterial pressure through radial artery catheters in neonates. The technique, which can be used for short-term monitoring, uses cannulation of the radial artery with a 24-gauge Teflon catheter, connected by a Luer-Lok fitting to a three-way stopcock and a high-fidelity tip transducer. In vitro studies showed that the system is linear and the frequency response is flat (+/- 3 dB) up to 50 Hz. The technique permits gathering of high-quality pressure data and can be used in the area of neonatal clinical research for short-term monitoring. It needs to be developed further before routine application in clinical practice can be recommended.

Arteries↗
PubMed1990

Retrograde flow detection in the radial artery as a means to assess palmar collateral circulation in newborn infants.

The aim of this clinical study was to determine whether Doppler ultrasound can be used in newborn infants to assess the adequacy of palmar collateral circulation. Retrograde flow in the radial artery, distal to the site of manual occlusion of the vessel, was studied by Doppler technique. Forty-seven newborn infants, who underwent percutaneous radial artery cannulation were studied. Prior to cannulation palmar collateral circulation was tested in each infant, using the timed Allen test and was considered to be adequate. Pulsatile retrograde flow could be demonstrated in 11 out of 47 infants, but not in 36 of the 47 studied. During the period of cannulation none of the infants showed any sign of vascular insufficiency of the hand. It can be concluded that in newborn infants, the detection of pulsatile retrograde flow in the radial artery, using a Doppler flow meter, does not appear to have advantages over the Allen test as an indicator of adequate palmar collateral circulation.

Arteries↗
PubMed1989

Fat absorption in premature infants: the effect of lard and antibiotics.

Fat absorption of an adapted cow's milk formula was studied in a randomized controlled trial involving two groups of 18 premature infants (mean gestational age +/- SD: 33.0 +/- 2.9 weeks, range 26.5-37.5 weeks). The triglyceride configuration was modified by the use of lard. This modification did not improve the absorption of fat or energy. Also no difference in serum concentrations of cholesterol and triglycerides was found. Growth velocity during the study was similar in both groups. Detailed analysis of the data revealed that in infants who received (parenterally) antibiotics (mainly ampicillin and netilmicin) a higher coefficient of fat absorption (+20%, P less than 0.01) and of energy absorption (+8%, P = 0.03) was found. Based on these results, we find no support for the use of lard in adapted cow's milk infant formulas to improve fat absorption. In studies of fat and energy absorption the effects of antibiotics have to be taken into account.

Anti-Bacterial Agents↗
PubMed1989

Skin blood flow changes during apneic spells in preterm infants.

Changes in skin blood flow during apneic spells were determined in 18 preterm infants using a diode laser Doppler flow meter without light conducting fibres. Heart rate, nasal air flow, impedance pneumography, skin and incubator temperature and laser Doppler skin blood flow were recorded simultaneously in each infant. During 212 apneic spells with a duration of 11.6 +/- 7.5 s (mean +/- S.D.) (range 6.0-48.0 s), the laser Doppler skin blood flow was measured. In all children except one, the majority of the apneic spells was associated with a decrease in skin blood flow. During 155 apneic spells (73%) skin blood flow decreased significantly P less than 0.025), the maximum decrease being 16.7 +/- 14.8%, 28.5 +/- 23.9% and 18.9 +/- 16.1% (mean +/- S.D.) for central, obstructive and mixed apneic spells, respectively. The decrease in skin blood flow started immediately after the beginning of apneic spells in 71%, the rest started with a mean delay of 3.4 s (range 0.1-7.0 s). No relation was found between the decrease in skin blood flow and the duration of the apneic spells. Thirty-four percent of the apneic spells were accompanied by bradycardia. In apneic spells accompanied by bradycardia the decrease in skin blood flow was not related to the fall in heart rate.

Blood Flow Velocity↗