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Biomedical subjects

P Glass

Publications and source records attributed to P Glass.

At least 19 recordsLinked to original sources
PubMed1992

Mortality and morbidity rates among lower birth weight infants (2000 to 2500 grams) treated with extracorporeal membrane oxygenation.

To assess the validity of the currently accepted lower weight limit of 2 kg for treatment of neonates with extracorporeal membrane oxygenation (ECMO), we reviewed the outcome of lower birth weight (2.0 to 2.5 kg, n = 29) and higher birth weight (n = 235) for infants treated with venoarterial ECMO at our institution from 1984 through 1990. Newborn infants with congenital diaphragmatic hernia were not included. The mortality rate was significantly greater after venoarterial ECMO in lower than in higher birth weight infants (relative risk 3.45; confidence interval = (1.68, 5.79)). For infants with the diagnosis of respiratory distress syndrome, the mortality rate was 56% (5/9) for lower and 8% (2/25) for higher birth weight infants (p less than 0.01). The most frequent cause of death in lower birth weight infants was intracranial hemorrhage (7/10 deaths). The overall incidence of any neuroimaging abnormality was significantly greater for lower birth weight infants (p = 0.044), primarily because of the higher incidence of major intracranial hemorrhage. Finally, the risk of developmental delay (development quotient less than 70 at 1 to 2 years of age) among survivors available for follow-up was significantly higher among the lower than the higher birth weight infants. These outcome data suggest that further reduction of the current lower weight limit for ECMO should not become standard without prospective research or technologic advances.

Birth Weight↗
PubMed1991

Posterior fossa intracranial hemorrhage in infants treated with extracorporeal membrane oxygenation: sonographic findings.

Posterior fossa hemorrhage was documented by autopsy in five infants who had been treated with extracorporeal membrane oxygenation over a 5-year-period. In all five cases, the diagnosis was made prospectively by cranial sonography. Sonographic findings were compared with those in a control group of 15 infants with normal posterior fossae at autopsy. The following sonographic abnormalities were exhibited in neonates with posterior fossae hemorrhage: loss of definition of the cerebellum and fourth ventricle on midline sagittal images, heterogeneous cerebellar parenchyma, focal hypoechoic lesions, ventricular dilatation, and tentorial abnormalities. Bright foci inferior to the third ventricle were seen in four neonates in the normal control group. These foci measured 5-10 mm in diameter. One cranial sonogram was falsely interpreted as showing a posterior fossa hemorrhage because of prominent echoes in the interpeduncular cistern. Infants treated with extracorporeal membrane oxygenation are at risk for developing posterior fossa hemorrhage. Awareness of sonographic signs and potential pitfalls in the interpretation of posterior fossa hemorrhage is important for early and accurate recognition of these unusual and sometimes treatable hemorrhages.

Cerebral Hemorrhage↗
PubMed1990

Light and the developing retina.

Retinopathy of prematurity (ROP) has increased in the United States in the past decade. Its resurgence has been attributed to advances in medical care which have increased the survival of infants less than 1000 g. Retinal immaturity and exposure to supplementary oxygen are generally accepted as the principal factors associated with ROP, however precocious exposure of the immature retina to light may also contribute. The preterm infant is routinely exposed for the duration of hospital stay to bright continuous light at levels which produce retinal damage in animals. A recent study has provided evidence implicating light in ROP. Preterm infants for whom the light levels were reduced had a lower incidence of ROP, compared to a similar group of preterms exposed to standard levels of nursery light. Given the problems of a non-randomized design, the results must be considered preliminary; however the findings are substantiated by parallel results in both hospitals studied and by an effect of exposure to light within the treatment group. Speculations regarding the mechanisms of light as a contributor to ROP include: alterations of retinal metabolism, cellular damage by phototoxicity, and the generation of free radicals. Mechanisms of phototoxicity are compatible with theories of oxygen toxicity. Light may not be necessary for ROP to occur, but it may increase the risk.

Animals↗
PubMed1990

[Effect of alloxans on pancreatic B-cells with special regard to the alloxan-metal-complex theory. I. Effects of alloxan, alloxan-zinc chelates, dilauric acid and colchicine on blood sugar and rate of mitosis of B-cell Langerhans islets].

Alloxan, alloxan-zinc-chelate, sodium salt of dialuric acid, and colchicine significantly raised the blood sugar level under the previously mentioned experimental conditions 28 h after the application. The typical three-phase blood sugar curve development after alloxan (initial hyperglycemia, hypoglycemia, permanent hyperglycemia) was only approximately reached by dialuric acid which initiated, however, instead of the initial hyperglycemia a more pronounced hypoglycemic phase within the first 6 h. Alloxan-zinc-chelate protractedly and significantly made the blood sugar's increase up to the 7th d post injectionem, without being able to maintain a permanent hyperglycemia with half-normal dosage in comparison with alloxan. Non-diabetogenic alloxan doses (19 mg/kg i. v.) and the appropriate alloxan-zinc-chelate dosage (35 mg/kg) led to a significant increase of the blood sugar only in the chelate group with the long-term test up to 10 d, suggesting an increased and prolonged effect of the metal-chelates by stabilization of alloxan. The tested substances differently acted on the mitotic frequency of B-cells. The mitosis did not increase in the alloxan-zinc- and dialuric acid treated animals and was similar to normal animals far below the fractions of 1/10(6). A 4- and 5-fold increase of the mitotic frequency in the colchicine or alloxan treated animals as well as an accumulation of delayed metaphases suggest an impeded transition to the anaphase and include alloxan among the mitotic poisons.

Alloxan↗
PubMed1989

CT of cerebrovascular injury after neonatal extracorporeal membrane oxygenation: implications for neurodevelopmental outcome.

One hundred forty-six neonates treated with extracorporeal membrane oxygenation (ECMO) were evaluated with cranial sonography and CT at different times in the course of their disease. Cranial sonography was performed during treatment with ECMO, and CT was done 3-14 days after cessation of ECMO bypass. In 66 (45%), intracranial abnormalities were detected with either sonography or CT. Thirty neonates had hemorrhages only, 24 had nonhemorrhagic abnormalities, and 12 had combined lesions. CT provided additional information in 44 (67%) of the 66 neonates. Sonography was normal in 37 neonates, showed fewer lesions in 10 neonates, and was concordant with CT findings in 14 neonates. It cannot be established whether these lesions went undetected with sonography during ECMO, or occurred after cessation of ECMO bypass. Neurodevelopmental evaluation was performed in 71 of 90 survivors 1 year of age or older. Forty-three infants (61%) were normal; developmental delay was suspected in 12 (17%) and present in 16 (23%). The severity of intracranial abnormality as determined by a neuroimaging score correlated well with short-term developmental outcome. Mean neuroimaging scores were significantly higher, with increasing degree of neurodevelopmental delay (p less than .001 by Kruskal-Wallis rank order test). Although cranial sonography remains the primary technique for the detection of life-threatening hemorrhage during ECMO, cranial CT after ECMO is important in defining the total degree of intracranial injury present in these high-risk neonates.

Cerebral Hemorrhage↗
PubMed1989

Alfentanil and midazolam: new anesthetic drugs for continuous infusion and an automated method of administration.

New drugs like alfentanil and midazolam have the primary advantage of metabolizing faster than existing compounds in their class. Because of shorter plasma half-lives, the drugs are well suited for continuous infusion. In our hands, CACI is a valuable clinical instrument and research tool. Although some anesthetic drugs can be given safely and effectively by bolus injection, whenever a titrated continuous infusion is appropriate (and physiologically closed-loop delivery is not possible), use of a CACI-type instrument should be the preferred method of administration. With the availability for continuous infusion of alfentanil and midazolam, with their highly desirable pharmacodynamic properties and relatively effervescent pharmacokinetics, we believe that computerized pharmacokinetic model-driven infusion devices will play a significant role in future anesthetic practice.

Alfentanil↗
PubMed1989

Morbidity for survivors of extracorporeal membrane oxygenation: neurodevelopmental outcome at 1 year of age.

Extracorporeal membrane oxygenation is an important technology in the treatment of high-risk infants whose long-term outcome is being followed prospectively at our institution. The extracorporeal membrane oxygenation procedure allows temporary cardiopulmonary support for critically ill full-term neonates who are refractory to maximum ventilatory and medical management as a consequence of severe persistent pulmonary hypertension. The technique necessitates both the permanent ligation of the right common carotid artery and jugular vein and systemic heparinization. The survivors constitute a unique group of high-risk infants, from the standpoint of the hypoxic-ischemic insults preceding extracorporeal membrane oxygenation and the risks associated with the procedure. Our results indicate that most of our survivors are developing normally at 1 year. Major morbidity, in terms of either significant developmental delay (Bayley mental and motor indices less than 70) or significant neuromotor abnormality, occurred in only 10% of these infants. Poor outcome was associated with major intracranial hemorrhage and chronic lung disease. Ligation of the right carotid artery and jugular vein was not associated with a consistent lateralizing lesion. Long-term follow-up through school age is essential.

Asphyxia Neonatorum↗
PubMed1988

Do evoked potentials measure depth of anaesthesia?

Somatosensory evoked potentials have been suggested as a possible neurophysiological in of anaesthetic depth. In order to test the usefulness of this technique of monitoring, 8 patients were monitored during balanced anaesthesia. Following induction with a sleep dose of thiopentone, a neuromuscular blocking agent was used and the patients' lungs ventilated with N2O/O2(F1O2 = 0.3). This was supplemented with halothane or fentanyl. Somatosensory evoked potentials were recorded every 10 minutes during surgery, blood pressure and heart rate being recorded at the end of each evoked potential measurement. Induction of anaesthesia was associated with the reduction in SEP amplitude from 4.2 +/- 1.04 micro volts to 1.6 +/- 0.9 micro volts. There was an increase in latency from 19.2 +/- 1.3 msec to 20.0 +/- 1.3 msec to 20.0 +/- 1.5 msec. Recovery from anaesthesia was accompanied by an increase in SEP amplitude pre-induction values. There were no apparent correlations between the changes in evoked potential measures and changes in heart rate or blood pressure. Consistent change in somatosensory evoked potentials (prolonged latency, decreased amplitude) occurred with both narcotic and volatile anaesthetics. There was a recovery of evoked potentials at the end of anaesthesia. This is a promising technique, worthy of further evaluation.

Anesthesia Recovery Period↗
PubMed1988

Cerebral hemodynamics in infants undergoing extracorporeal membrane oxygenation: further observations.

Intracranial Doppler ultrasonographic examinations were performed on 64 infants treated with extracorporeal membrane oxygenation (ECMO). Serial studies were performed on the anterior cerebral artery in 55 infants before and during ECMO bypass, and on the middle cerebral arteries (MCAs) and internal carotid arteries (ICAs) on an additional nine infants. The onset of ECMO was associated with changes in character of pulsatile flow, direction of flow, and mean blood-flow velocity. Pulsatility decreased in all patients, and mean blood-flow velocity increased in 73% of patients (mean change from baseline, 87%). Despite retrograde flow in the right ICA in five of nine infants, antegrade flow to the right MCA was preserved in all cases. We found no correlation between alterations in mean blood-flow velocity and overall mortality, frequency of intracranial hemorrhage, and neuro-developmental outcome. These data suggest that wide variations in cerebral blood flow occur with ECMO therapy, and that these changes appear to be well tolerated.

Blood Flow Velocity↗
PubMed1988

Retinopathy of prematurity: progress report.

For the time being, risk of ROP seems inexorably linked to survival of extremely low birth weight prematures, whose embryonic retinas develop in an abnormal and fluctuating environment. Incidence and severity may be reduced by stabilizing ventilation, oxygenation, and perfusion, moderating light exposure, and providing normal levels of vitamin E. Progression of stage 3 retinopathy may sometimes be arrested by cryotherapy. In the future, antioxidants or other pharmacologic agents may be developed to provide a greater margin of safety. In the meantime, the eyes of prematures must be examined and those with ROP will need specialized ophthalmologic care.

Humans↗
PubMed1988

Retinopathy of prematurity: what causes it?

Retinopathy of prematurity continues to be a major cause of morbidity in surviving prematures despite attempts to regulate oxygen. Developing retinal vessels apparently can be disrupted by any of a considerable number of influences. By far the preeminent risk factor is extreme prematurity itself.

Humans↗
PubMed1987

Neurologic status in infants treated with extracorporeal membrane oxygenation: correlation of imaging findings with developmental outcome.

A retrospective review was done of intracranial images obtained within the newborn period in 46 infants who had been treated with extracorporeal membrane oxygenation (ECMO). A neuroimaging score was determined on the basis of the extent and severity of findings on both ultrasound and computed tomographic scans. Presence of abnormality at neuroimaging and the neuroimaging score were correlated with the findings of neurodevelopmental evaluations (Bayley scales) performed in infants who were at a mean age of 11.8 months (range, 6-16 months). A significant inverse correlation was found between the neuroimaging score and mental and psychomotor development indexes of the Bayley scale (P less than .005). Mean neuroimaging scores in infants with normal development were significantly lower than those in infants with delayed development (P = .002). Although individual outcomes cannot be predicted with neuroimaging, the neuroimaging score can be a useful adjunct in assigning patients who survive with ECMO treatment to risk categories for developmental outcome.

Brain↗
PubMed1985

Effect of bright light in the hospital nursery on the incidence of retinopathy of prematurity.

The preterm infant is subjected to prolonged exposure to ambient nursery illumination at levels that have been found to produce retinal damage in animals. We prospectively investigated the effect of exposure to light in two intensive care nurseries by comparing the incidence of retinopathy of prematurity among 74 infants from the standard bright nursery environment (median light level, 60 foot-candles [ftc]) with the incidence among 154 infants of similar birth weight for whom the light levels were reduced (median, 25 ftc). There was a higher incidence of retinopathy of prematurity in the group of infants who had been exposed to the brighter nursery lights, particularly in those with birth weights below 1000 g (86 percent vs. 54 per cent, P less than 0.01 by chi-square test). We conclude that the high level of ambient illumination commonly found in the hospital nursery may be one factor contributing to retinopathy of prematurity and that safety standards with regard to current lighting practices should be reassessed.

Birth Weight↗